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Ali-Osman, Francis

Positions:

Margaret Harris and David Silverman Professor of Neuro-Oncology Research

Surgery, Surgical Sciences
School of Medicine

Professor of Surgery

Surgery, Surgical Sciences
School of Medicine

Professor in Pathology

Pathology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

D.Sc. 1982

D.Sc. — Free University of Berlin (Germany)

Grants:

Duke SPORE in Brain Cancer

Administered By
Neurosurgery
AwardedBy
National Institutes of Health
Role
Co-Principal Investigator
Start Date
September 24, 2014
End Date
August 31, 2019

P53-dependent GSTP1 Gene Regulation and Glioma Drug Resistance

Administered By
Surgery, Surgical Sciences
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2010
End Date
April 30, 2015

Protein Kinase C and GSTP1 interactions in glioma drug resistance

Administered By
Surgery, Surgical Sciences
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2008
End Date
May 31, 2014

NCI Howard Temin Award (K01) Transition

Administered By
Surgery, Surgical Sciences
AwardedBy
National Institutes of Health
Role
Co-Mentor
Start Date
September 25, 2006
End Date
July 31, 2012

Novel Targeted Therapeutics for CNS Malignancies

Administered By
Surgery, Surgical Sciences
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
February 10, 2006
End Date
December 31, 2011

Radionuclide-based Molecular Imaging of the DNA Repair Protein AGT

Administered By
Radiology
AwardedBy
National Institutes of Health
Role
Co Investigator
Start Date
March 01, 2009
End Date
February 28, 2011

DNA Methylation and GSTP1 Gene Regulation in Gliomas

Administered By
Surgery, Surgical Sciences
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
September 01, 2002
End Date
June 30, 2008

Planning a Duke Academic Public Private Partnership Program (AP4) Center

Administered By
Duke Cancer Institute
AwardedBy
National Cancer Institute
Role
Co-Principal Investigator
Start Date
July 20, 2004
End Date
June 30, 2006
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Publications:

Genome-wide association study of glioma subtypes identifies specific differences in genetic susceptibility to glioblastoma and non-glioblastoma tumors.

Genome-wide association studies (GWAS) have transformed our understanding of glioma susceptibility, but individual studies have had limited power to identify risk loci. We performed a meta-analysis of existing GWAS and two new GWAS, which totaled 12,496 cases and 18,190 controls. We identified five new loci for glioblastoma (GBM) at 1p31.3 (rs12752552; P = 2.04 × 10(-9), odds ratio (OR) = 1.22), 11q14.1 (rs11233250; P = 9.95 × 10(-10), OR = 1.24), 16p13.3 (rs2562152; P = 1.93 × 10(-8), OR = 1.21), 16q12.1 (rs10852606; P = 1.29 × 10(-11), OR = 1.18) and 22q13.1 (rs2235573; P = 1.76 × 10(-10), OR = 1.15), as well as eight loci for non-GBM tumors at 1q32.1 (rs4252707; P = 3.34 × 10(-9), OR = 1.19), 1q44 (rs12076373; P = 2.63 × 10(-10), OR = 1.23), 2q33.3 (rs7572263; P = 2.18 × 10(-10), OR = 1.20), 3p14.1 (rs11706832; P = 7.66 × 10(-9), OR = 1.15), 10q24.33 (rs11598018; P = 3.39 × 10(-8), OR = 1.14), 11q21 (rs7107785; P = 3.87 × 10(-10), OR = 1.16), 14q12 (rs10131032; P = 5.07 × 10(-11), OR = 1.33) and 16p13.3 (rs3751667; P = 2.61 × 10(-9), OR = 1.18). These data substantiate that genetic susceptibility to GBM and non-GBM tumors are highly distinct, which likely reflects different etiology.

Authors
Melin, BS; Barnholtz-Sloan, JS; Wrensch, MR; Johansen, C; Il'yasova, D; Kinnersley, B; Ostrom, QT; Labreche, K; Chen, Y; Armstrong, G; Liu, Y; Eckel-Passow, JE; Decker, PA; Labussière, M; Idbaih, A; Hoang-Xuan, K; Di Stefano, A-L; Mokhtari, K; Delattre, J-Y; Broderick, P; Galan, P; Gousias, K; Schramm, J; Schoemaker, MJ; Fleming, SJ; Herms, S; Heilmann, S; Nöthen, MM; Wichmann, H-E; Schreiber, S; Swerdlow, A; Lathrop, M; Simon, M; Sanson, M; Andersson, U; Rajaraman, P; Chanock, S; Linet, M et al.
MLA Citation
Melin, BS, Barnholtz-Sloan, JS, Wrensch, MR, Johansen, C, Il'yasova, D, Kinnersley, B, Ostrom, QT, Labreche, K, Chen, Y, Armstrong, G, Liu, Y, Eckel-Passow, JE, Decker, PA, Labussière, M, Idbaih, A, Hoang-Xuan, K, Di Stefano, A-L, Mokhtari, K, Delattre, J-Y, Broderick, P, Galan, P, Gousias, K, Schramm, J, Schoemaker, MJ, Fleming, SJ, Herms, S, Heilmann, S, Nöthen, MM, Wichmann, H-E, Schreiber, S, Swerdlow, A, Lathrop, M, Simon, M, Sanson, M, Andersson, U, Rajaraman, P, Chanock, S, and Linet, M et al. "Genome-wide association study of glioma subtypes identifies specific differences in genetic susceptibility to glioblastoma and non-glioblastoma tumors." Nature genetics (March 27, 2017).
PMID
28346443
Source
epmc
Published In
Nature Genetics
Publish Date
2017
DOI
10.1038/ng.3823

New insights into estrogenic regulation of O6-methylguanine DNA-methyltransferase (MGMT) in human breast cancer cells: Co-degradation of ER-α and MGMT proteins by fulvestrant or O6-benzylguanine indicates fresh avenues for therapy.

Endocrine therapy using estrogen receptor-α (ER-α) antagonists for attenuating horm2one-driven cell proliferation is a major treatment modality for breast cancers. To exploit any DNA repair deficiencies associated with endocrine therapy, we investigated the functional and physical interactions of ER-α with O6-methylguanine DNA methyltransferase (MGMT), a unique DNA repair protein that confers tumor resistance to various anticancer alkylating agents. The ER-α -positive breast cancer cell lines (MCF-7, T47D) and ER- negative cell lines (MDAMB-468, MDAMB-231), and established inhibitors of ER-α and MGMT, namely, ICI-182,780 (Faslodex) and O6-benzylguanine, respectively, were used to study MGMT- ER interactions. The MGMT gene promoter was found to harbor one full and two half estrogen-responsive elements (EREs) and two antioxidant-responsive elements (AREs). MGMT expression was upregulated by estrogen, downregulated by tamoxifen in Western blot and promoter-linked reporter assays. Similarly, both transient and stable transfections of Nrf-2 (nuclear factor-erythroid 2-related factor-2) increased the levels of MGMT protein and activity 3 to 4-fold reflecting novel regulatory nodes for this drug-resistance determinant. Of the different ER-α antagonists tested, the pure anti-estrogen fulvestrant was most potent in inhibiting the MGMT activity in a dose, time and ER-α dependent manner, similar to O6-benzylguanine. Interestingly, fulvestrant exposure led to a degradation of both ER-α and MGMT proteins and O6-benzylguanine also induced a specific loss of ER-α and MGMT proteins in MCF-7 and T47D breast cancer cells with similar kinetics. Immunoprecipitation revealed a specific association of ER-α and MGMT proteins in breast cancer cells. Furthermore, silencing of MGMT gene expression triggered a decrease in the levels of both MGMT and ER-α proteins. The involvement of proteasome in the drug-induced degradation of both proteins was also demonstrated. Fulvestrant enhanced the cytotoxicity of MGMT-targeted alkylating agents, namely, temozolomide and BCNU by 3 to 4-fold in ER-α positive cells, but not in ER-negative cells. We conclude that MGMT and ER-α proteins exist as a complex and are co-targeted for ubiquitin-conjugation and subsequent proteasomal degradation. The findings offer a clear rationale for combining alkylating agents with endocrine therapy.

Authors
Paranjpe, A; Bailey, NI; Konduri, S; Bobustuc, GC; Ali-Osman, F; Yusuf, MA; Punganuru, SR; Madala, HR; Basak, D; Mostofa, A; Srivenugopal, KS
MLA Citation
Paranjpe, A, Bailey, NI, Konduri, S, Bobustuc, GC, Ali-Osman, F, Yusuf, MA, Punganuru, SR, Madala, HR, Basak, D, Mostofa, A, and Srivenugopal, KS. "New insights into estrogenic regulation of O6-methylguanine DNA-methyltransferase (MGMT) in human breast cancer cells: Co-degradation of ER-α and MGMT proteins by fulvestrant or O6-benzylguanine indicates fresh avenues for therapy." Journal of biomedical research 30.5 (September 2016): 393-410.
PMID
27845303
Source
epmc
Published In
Journal of Biomedical Research
Volume
30
Issue
5
Publish Date
2016
Start Page
393
End Page
410
DOI
10.7555/jbr.30.20160040

History of chickenpox in glioma risk: a report from the glioma international case-control study (GICC).

Varicella zoster virus (VZV) is a neurotropic α-herpesvirus that causes chickenpox and establishes life-long latency in the cranial nerve and dorsal root ganglia of the host. To date, VZV is the only virus consistently reported to have an inverse association with glioma. The Glioma International Case-Control Study (GICC) is a large, multisite consortium with data on 4533 cases and 4171 controls collected across five countries. Here, we utilized the GICC data to confirm the previously reported associations between history of chickenpox and glioma risk in one of the largest studies to date on this topic. Using two-stage random-effects restricted maximum likelihood modeling, we found that a positive history of chickenpox was associated with a 21% lower glioma risk, adjusting for age and sex (95% confidence intervals (CI): 0.65-0.96). Furthermore, the protective effect of chickenpox was stronger for high-grade gliomas. Our study provides additional evidence that the observed protective effect of chickenpox against glioma is unlikely to be coincidental. Future studies, including meta-analyses of the literature and investigations of the potential biological mechanism, are warranted.

Authors
Amirian, ES; Scheurer, ME; Zhou, R; Wrensch, MR; Armstrong, GN; Lachance, D; Olson, SH; Lau, CC; Claus, EB; Barnholtz-Sloan, JS; Il'yasova, D; Schildkraut, J; Ali-Osman, F; Sadetzki, S; Jenkins, RB; Bernstein, JL; Merrell, RT; Davis, FG; Lai, R; Shete, S; Amos, CI; Melin, BS; Bondy, ML
MLA Citation
Amirian, ES, Scheurer, ME, Zhou, R, Wrensch, MR, Armstrong, GN, Lachance, D, Olson, SH, Lau, CC, Claus, EB, Barnholtz-Sloan, JS, Il'yasova, D, Schildkraut, J, Ali-Osman, F, Sadetzki, S, Jenkins, RB, Bernstein, JL, Merrell, RT, Davis, FG, Lai, R, Shete, S, Amos, CI, Melin, BS, and Bondy, ML. "History of chickenpox in glioma risk: a report from the glioma international case-control study (GICC)." Cancer medicine 5.6 (June 2016): 1352-1358.
PMID
26972449
Source
epmc
Published In
Cancer Medicine
Volume
5
Issue
6
Publish Date
2016
Start Page
1352
End Page
1358
DOI
10.1002/cam4.682

Approaching a Scientific Consensus on the Association between Allergies and Glioma Risk: A Report from the Glioma International Case-Control Study.

Several previous studies have found inverse associations between glioma susceptibility and a history of allergies or other atopic conditions. Some evidence indicates that respiratory allergies are likely to be particularly relevant with regard to glioma risk. Using data from the Glioma International Case-Control Study (GICC), we examined the effects of respiratory allergies and other atopic conditions on glioma risk.The GICC contains detailed information on history of atopic conditions for 4,533 cases and 4,171 controls, recruited from 14 study sites across five countries. Using two-stage random-effects restricted maximum likelihood modeling to calculate meta-analysis ORs, we examined the associations between glioma and allergy status, respiratory allergy status, asthma, and eczema.Having a history of respiratory allergies was associated with an approximately 30% lower glioma risk, compared with not having respiratory allergies (mOR, 0.72; 95% confidence interval, 0.58-0.90). This association was similar when restricting to high-grade glioma cases. Asthma and eczema were also significantly protective against glioma.A substantial amount of data on the inverse association between atopic conditions and glioma has accumulated, and findings from the GICC study further strengthen the existing evidence that the relationship between atopy and glioma is unlikely to be coincidental.As the literature approaches a consensus on the impact of allergies in glioma risk, future research can begin to shift focus to what the underlying biologic mechanism behind this association may be, which could, in turn, yield new opportunities for immunotherapy or cancer prevention.

Authors
Amirian, ES; Zhou, R; Wrensch, MR; Olson, SH; Scheurer, ME; Il'yasova, D; Lachance, D; Armstrong, GN; McCoy, LS; Lau, CC; Claus, EB; Barnholtz-Sloan, JS; Schildkraut, J; Ali-Osman, F; Sadetzki, S; Johansen, C; Houlston, RS; Jenkins, RB; Bernstein, JL; Merrell, RT; Davis, FG; Lai, R; Shete, S; Amos, CI; Melin, BS; Bondy, ML
MLA Citation
Amirian, ES, Zhou, R, Wrensch, MR, Olson, SH, Scheurer, ME, Il'yasova, D, Lachance, D, Armstrong, GN, McCoy, LS, Lau, CC, Claus, EB, Barnholtz-Sloan, JS, Schildkraut, J, Ali-Osman, F, Sadetzki, S, Johansen, C, Houlston, RS, Jenkins, RB, Bernstein, JL, Merrell, RT, Davis, FG, Lai, R, Shete, S, Amos, CI, Melin, BS, and Bondy, ML. "Approaching a Scientific Consensus on the Association between Allergies and Glioma Risk: A Report from the Glioma International Case-Control Study." Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 25.2 (February 2016): 282-290.
PMID
26908595
Source
epmc
Published In
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology
Volume
25
Issue
2
Publish Date
2016
Start Page
282
End Page
290
DOI
10.1158/1055-9965.epi-15-0847

The Glioma International Case-Control Study: A Report From the Genetic Epidemiology of Glioma International Consortium.

Decades of research have established only a few etiological factors for glioma, which is a rare and highly fatal brain cancer. Common methodological challenges among glioma studies include small sample sizes, heterogeneity of tumor subtypes, and retrospective exposure assessment. Here, we briefly describe the Glioma International Case-Control (GICC) Study (recruitment, 2010-2013), a study being conducted by the Genetic Epidemiology of Glioma International Consortium that integrates data from multiple data collection sites, uses a common protocol and questionnaire, and includes biospecimen collection. To our knowledge, the GICC Study is the largest glioma study to date that includes collection of blood samples, which will allow for genetic analysis and interrogation of gene-environment interactions.

Authors
Amirian, ES; Armstrong, GN; Zhou, R; Lau, CC; Claus, EB; Barnholtz-Sloan, JS; Il'yasova, D; Schildkraut, J; Ali-Osman, F; Sadetzki, S; Johansen, C; Houlston, RS; Jenkins, RB; Lachance, D; Olson, SH; Bernstein, JL; Merrell, RT; Wrensch, MR; Davis, FG; Lai, R; Shete, S; Amos, CI; Scheurer, ME; Aldape, K; Alafuzoff, I; Brännström, T; Broholm, H; Collins, P; Giannini, C; Rosenblum, M; Tihan, T; Melin, BS; Bondy, ML
MLA Citation
Amirian, ES, Armstrong, GN, Zhou, R, Lau, CC, Claus, EB, Barnholtz-Sloan, JS, Il'yasova, D, Schildkraut, J, Ali-Osman, F, Sadetzki, S, Johansen, C, Houlston, RS, Jenkins, RB, Lachance, D, Olson, SH, Bernstein, JL, Merrell, RT, Wrensch, MR, Davis, FG, Lai, R, Shete, S, Amos, CI, Scheurer, ME, Aldape, K, Alafuzoff, I, Brännström, T, Broholm, H, Collins, P, Giannini, C, Rosenblum, M, Tihan, T, Melin, BS, and Bondy, ML. "The Glioma International Case-Control Study: A Report From the Genetic Epidemiology of Glioma International Consortium." American journal of epidemiology 183.2 (January 2016): 85-91.
PMID
26656478
Source
epmc
Published In
American Journal of Epidemiology
Volume
183
Issue
2
Publish Date
2016
Start Page
85
End Page
91
DOI
10.1093/aje/kwv235

Long-Term Follow-up Results: A Phase 2 Trial of Imatinib Mesylate As Maintenance Therapy for Patients with Newly Diagnosed c-Kit Positive Acute Myeloid Leukemia (AML)

Authors
Advani, AS; Tse, W; Jia, X; Elson, P; Cooper, B; Ali-Osman, F; Park, J; Rao, AV; Rizzieri, DA; Wang, ES; Cotta, CV; Kalaycio, M; Sobecks, RM; Rouphail, B; Maciejewski, JP; Fensterl, J; Bailey, L; Carew, JS; Foster, B; Rush, ML; Adams, D; Griffiths, EA; Sekeres, MA
MLA Citation
Advani, AS, Tse, W, Jia, X, Elson, P, Cooper, B, Ali-Osman, F, Park, J, Rao, AV, Rizzieri, DA, Wang, ES, Cotta, CV, Kalaycio, M, Sobecks, RM, Rouphail, B, Maciejewski, JP, Fensterl, J, Bailey, L, Carew, JS, Foster, B, Rush, ML, Adams, D, Griffiths, EA, and Sekeres, MA. "Long-Term Follow-up Results: A Phase 2 Trial of Imatinib Mesylate As Maintenance Therapy for Patients with Newly Diagnosed c-Kit Positive Acute Myeloid Leukemia (AML)." December 3, 2015.
Source
wos-lite
Published In
Blood
Volume
126
Issue
23
Publish Date
2015

Phosphorylation of Glutathione S-Transferase P1 (GSTP1) by Epidermal Growth Factor Receptor (EGFR) Promotes Formation of the GSTP1-c-Jun N-terminal kinase (JNK) Complex and Suppresses JNK Downstream Signaling and Apoptosis in Brain Tumor Cells.

Under normal physiologic conditions, the glutathione S-transferase P1 (GSTP1) protein exists intracellularly as a dimer in reversible equilibrium with its monomeric subunits. In the latter form, GSTP1 binds to the mitogen-activated protein kinase, JNK, and inhibits JNK downstream signaling. In tumor cells, which frequently are characterized by constitutively high GSTP1 expression, GSTP1 undergoes phosphorylation by epidermal growth factor receptor (EGFR) at tyrosine residues 3, 7, and 198. Here we report on the effect of this EGFR-dependent GSTP1 tyrosine phosphorylation on the interaction of GSTP1 with JNK, on the regulation of JNK downstream signaling by GSTP1, and on tumor cell survival. Using in vitro and in vivo growing human brain tumors, we show that tyrosine phosphorylation shifts the GSTP1 dimer-monomer equilibrium to the monomeric state and facilitates the formation of the GSTP1-JNK complex, in which JNK is functionally inhibited. Targeted mutagenesis and functional analysis demonstrated that the increased GSTP1 binding to JNK results from phosphorylation of the GSTP1 C-terminal Tyr-198 by EGFR and is associated with a >2.5-fold decrease in JNK downstream signaling and a significant suppression of both spontaneous and drug-induced apoptosis in the tumor cells. The findings define a novel mechanism of regulatory control of JNK signaling that is mediated by the EGFR/GSTP1 cross-talk and provides a survival advantage for tumors with activated EGFR and high GSTP1 expression. The results lay the foundation for a novel strategy of dual EGFR/GSTP1 for treating EGFR+ve, GSTP1 expressing GBMs.

Authors
Okamura, T; Antoun, G; Keir, ST; Friedman, H; Bigner, DD; Ali-Osman, F
MLA Citation
Okamura, T, Antoun, G, Keir, ST, Friedman, H, Bigner, DD, and Ali-Osman, F. "Phosphorylation of Glutathione S-Transferase P1 (GSTP1) by Epidermal Growth Factor Receptor (EGFR) Promotes Formation of the GSTP1-c-Jun N-terminal kinase (JNK) Complex and Suppresses JNK Downstream Signaling and Apoptosis in Brain Tumor Cells." The Journal of biological chemistry 290.52 (December 2015): 30866-30878.
PMID
26429914
Source
epmc
Published In
The Journal of biological chemistry
Volume
290
Issue
52
Publish Date
2015
Start Page
30866
End Page
30878
DOI
10.1074/jbc.m115.656140

Geriatric trauma G-60 falls with hip fractures: A pilot study of acute pain management using femoral nerve fascia iliac blocks.

Hip fractures due to falls cause significant morbidity and mortality among geriatric patients. A significant unmet need is an optimal pain management strategy. Consequently, patients are treated with standard analgesic care (SAC) regimens, which deliver high narcotic doses. However, narcotics are associated with delirium as well as gastrointestinal and respiratory failure risks. The purpose of this pilot study was to determine the safety and effectiveness of ultrasound-guided continuous compartmental fascia iliaca block (CFIB) in patients 60 years or older with hip fractures in comparison with SAC alone.We performed a retrospective study of 108 patients 60 years or older, with acute pain secondary to hip fracture (2012-2013). Patient variables were age, sex, comorbidities, and Injury Severity Score (ISS). Primary outcome was pain scores; secondary outcomes included hospital length of stay, discharge disposition, morbidity, and mortality. Statistical analysis was performed using (IBM SPSS version 22). For group comparison (SAC vs. SAC + CFIB) median test, repeated-measures analysis and Student's t test of transformed pain scores were used.Sixty-four patients received SAC only, and 44 patients received SAC + CFIB. Each CFIB placement was successful on first attempt without complications. Median time from emergency department arrival to block placement was 12.5 hours (interquartile range, 4-22 hours). Patients who received SAC + CFIB had significantly lower pain score ratings than patients treated with SAC alone. There were no differences in inpatient morbidity and mortality rates. Patients treated with SAC + CFIB were discharged home more often (p < 0.05).Ultrasound-guided CFIB is safe, practical, and readily integrated into the G-60 service for improved pain management of hip fractures. We are now conducting a prospective randomized control trial to confirm our observations.Therapeutic study, level IV.

Authors
Mangram, AJ; Oguntodu, OF; Hollingworth, AK; Prokuski, L; Steinstra, A; Collins, M; Sucher, JF; Ali-Osman, F; Dzandu, JK
MLA Citation
Mangram, AJ, Oguntodu, OF, Hollingworth, AK, Prokuski, L, Steinstra, A, Collins, M, Sucher, JF, Ali-Osman, F, and Dzandu, JK. "Geriatric trauma G-60 falls with hip fractures: A pilot study of acute pain management using femoral nerve fascia iliac blocks." The journal of trauma and acute care surgery 79.6 (December 2015): 1067-1072.
PMID
26680143
Source
epmc
Published In
Journal of Trauma and Acute Care Surgery
Volume
79
Issue
6
Publish Date
2015
Start Page
1067
End Page
1072
DOI
10.1097/ta.0000000000000841

Proteomic profiling of patient-derived glioblastoma xenografts identifies a subset with activated EGFR: implications for drug development.

The development of drugs to inhibit glioblastoma (GBM) growth requires reliable pre-clinical models. To date, proteomic level validation of widely used patient-derived glioblastoma xenografts (PDGX) has not been performed. In the present study, we characterized 20 PDGX models according to subtype classification based on The Cancer Genome Atlas criteria, TP53, PTEN, IDH 1/2, and TERT promoter genetic analysis, EGFR amplification status, and examined their proteomic profiles against those of their parent tumors. The 20 PDGXs belonged to three of four The Cancer Genome Atlas subtypes: eight classical, eight mesenchymal, and four proneural; none neural. Amplification of EGFR gene was observed in 9 of 20 xenografts, and of these, 3 harbored the EGFRvIII mutation. We then performed proteomic profiling of PDGX, analyzing expression/activity of several proteins including EGFR. Levels of EGFR phosphorylated at Y1068 vary considerably between PDGX samples, and this pattern was also seen in primary GBM. Partitioning of 20 PDGX into high (n = 5) and low (n = 15) groups identified a panel of proteins associated with high EGFR activity. Thus, PDGX with high EGFR activity represent an excellent pre-clinical model to develop therapies for a subset of GBM patients whose tumors are characterized by high EGFR activity. Further, the proteins found to be associated with high EGFR activity can be monitored to assess the effectiveness of targeting EGFR. The development of drugs to inhibit glioblastoma (GBM) growth requires reliable pre-clinical models. We validated proteomic profiles using patient-derived glioblastoma xenografts (PDGX), characterizing 20 PDGX models according to subtype classification based on The Cancer Genome Atlas (TCGA) criteria, TP53, PTEN, IDH 1/2, and TERT promoter genetic analysis, EGFR amplification status, and examined their proteomic profiles against those of their parent tumors. Proteins found to be associated with high EGFR activity represent potential biomarkers for GBM monitoring.

Authors
Brown, KE; Chagoya, G; Kwatra, SG; Yen, T; Keir, ST; Cooter, M; Hoadley, KA; Rasheed, A; Lipp, ES; Mclendon, R; Ali-Osman, F; Bigner, DD; Sampson, JH; Kwatra, MM
MLA Citation
Brown, KE, Chagoya, G, Kwatra, SG, Yen, T, Keir, ST, Cooter, M, Hoadley, KA, Rasheed, A, Lipp, ES, Mclendon, R, Ali-Osman, F, Bigner, DD, Sampson, JH, and Kwatra, MM. "Proteomic profiling of patient-derived glioblastoma xenografts identifies a subset with activated EGFR: implications for drug development." Journal of neurochemistry 133.5 (June 2015): 730-738.
PMID
25598002
Source
epmc
Published In
Journal of Neurochemistry
Volume
133
Issue
5
Publish Date
2015
Start Page
730
End Page
738
DOI
10.1111/jnc.13032

Targeted sequencing in chromosome 17q linkage region identifies familial glioma candidates in the Gliogene Consortium.

Glioma is a rare, but highly fatal, cancer that accounts for the majority of malignant primary brain tumors. Inherited predisposition to glioma has been consistently observed within non-syndromic families. Our previous studies, which involved non-parametric and parametric linkage analyses, both yielded significant linkage peaks on chromosome 17q. Here, we use data from next generation and Sanger sequencing to identify familial glioma candidate genes and variants on chromosome 17q for further investigation. We applied a filtering schema to narrow the original list of 4830 annotated variants down to 21 very rare (<0.1% frequency), non-synonymous variants. Our findings implicate the MYO19 and KIF18B genes and rare variants in SPAG9 and RUNDC1 as candidates worthy of further investigation. Burden testing and functional studies are planned.

Authors
Jalali, A; Amirian, ES; Bainbridge, MN; Armstrong, GN; Liu, Y; Tsavachidis, S; Jhangiani, SN; Plon, SE; Lau, CC; Claus, EB; Barnholtz-Sloan, JS; Il'yasova, D; Schildkraut, J; Ali-Osman, F; Sadetzki, S; Johansen, C; Houlston, RS; Jenkins, RB; Lachance, D; Olson, SH; Bernstein, JL; Merrell, RT; Wrensch, MR; Davis, FG; Lai, R; Shete, S; Aldape, K; Amos, CI; Muzny, DM; Gibbs, RA; Melin, BS; Bondy, ML
MLA Citation
Jalali, A, Amirian, ES, Bainbridge, MN, Armstrong, GN, Liu, Y, Tsavachidis, S, Jhangiani, SN, Plon, SE, Lau, CC, Claus, EB, Barnholtz-Sloan, JS, Il'yasova, D, Schildkraut, J, Ali-Osman, F, Sadetzki, S, Johansen, C, Houlston, RS, Jenkins, RB, Lachance, D, Olson, SH, Bernstein, JL, Merrell, RT, Wrensch, MR, Davis, FG, Lai, R, Shete, S, Aldape, K, Amos, CI, Muzny, DM, Gibbs, RA, Melin, BS, and Bondy, ML. "Targeted sequencing in chromosome 17q linkage region identifies familial glioma candidates in the Gliogene Consortium." Scientific reports 5 (February 5, 2015): 8278-.
PMID
25652157
Source
epmc
Published In
Scientific Reports
Volume
5
Publish Date
2015
Start Page
8278
DOI
10.1038/srep08278

Germline mutations in shelterin complex genes are associated with familial glioma.

Gliomas are the most common brain tumor, with several histological subtypes of various malignancy grade. The genetic contribution to familial glioma is not well understood. Using whole exome sequencing of 90 individuals from 55 families, we identified two families with mutations in POT1 (p.G95C, p.E450X), a member of the telomere shelterin complex, shared by both affected individuals in each family and predicted to impact DNA binding and TPP1 binding, respectively. Validation in a separate cohort of 264 individuals from 246 families identified an additional mutation in POT1 (p.D617Efs), also predicted to disrupt TPP1 binding. All families with POT1 mutations had affected members with oligodendroglioma, a specific subtype of glioma more sensitive to irradiation. These findings are important for understanding the origin of glioma and could have importance for the future diagnostics and treatment of glioma.

Authors
Bainbridge, MN; Armstrong, GN; Gramatges, MM; Bertuch, AA; Jhangiani, SN; Doddapaneni, H; Lewis, L; Tombrello, J; Tsavachidis, S; Liu, Y; Jalali, A; Plon, SE; Lau, CC; Parsons, DW; Claus, EB; Barnholtz-Sloan, J; Il'yasova, D; Schildkraut, J; Ali-Osman, F; Sadetzki, S; Johansen, C; Houlston, RS; Jenkins, RB; Lachance, D; Olson, SH; Bernstein, JL; Merrell, RT; Wrensch, MR; Walsh, KM; Davis, FG; Lai, R; Shete, S; Aldape, K; Amos, CI; Thompson, PA; Muzny, DM; Gibbs, RA; Melin, BS; Bondy, ML
MLA Citation
Bainbridge, MN, Armstrong, GN, Gramatges, MM, Bertuch, AA, Jhangiani, SN, Doddapaneni, H, Lewis, L, Tombrello, J, Tsavachidis, S, Liu, Y, Jalali, A, Plon, SE, Lau, CC, Parsons, DW, Claus, EB, Barnholtz-Sloan, J, Il'yasova, D, Schildkraut, J, Ali-Osman, F, Sadetzki, S, Johansen, C, Houlston, RS, Jenkins, RB, Lachance, D, Olson, SH, Bernstein, JL, Merrell, RT, Wrensch, MR, Walsh, KM, Davis, FG, Lai, R, Shete, S, Aldape, K, Amos, CI, Thompson, PA, Muzny, DM, Gibbs, RA, Melin, BS, and Bondy, ML. "Germline mutations in shelterin complex genes are associated with familial glioma." Journal of the National Cancer Institute 107.1 (January 2015): 384-.
PMID
25482530
Source
epmc
Published In
Journal of the National Cancer Institute
Volume
107
Issue
1
Publish Date
2015
Start Page
384
DOI
10.1093/jnci/dju384

Proteomic profiling of patient-derived glioblastoma xenografts identifies a subset with activated EGFR: Implications for drug development

© 2015 International Society for Neurochemistry.The development of drugs to inhibit glioblastoma (GBM) growth requires reliable pre-clinical models. To date, proteomic level validation of widely used patient-derived glioblastoma xenografts (PDGX) has not been performed. In the present study, we characterized 20 PDGX models according to subtype classification based on The Cancer Genome Atlas criteria, TP53, PTEN, IDH 1/2, and TERT promoter genetic analysis, EGFR amplification status, and examined their proteomic profiles against those of their parent tumors. The 20 PDGXs belonged to three of four The Cancer Genome Atlas subtypes: eight classical, eight mesenchymal, and four proneural; none neural. Amplification of EGFR gene was observed in 9 of 20 xenografts, and of these, 3 harbored the EGFRvIII mutation. We then performed proteomic profiling of PDGX, analyzing expression/activity of several proteins including EGFR. Levels of EGFR phosphorylated at Y1068 vary considerably between PDGX samples, and this pattern was also seen in primary GBM. Partitioning of 20 PDGX into high (n = 5) and low (n = 15) groups identified a panel of proteins associated with high EGFR activity. Thus, PDGX with high EGFR activity represent an excellent pre-clinical model to develop therapies for a subset of GBM patients whose tumors are characterized by high EGFR activity. Further, the proteins found to be associated with high EGFR activity can be monitored to assess the effectiveness of targeting EGFR.

Authors
Brown, KE; Chagoya, G; Kwatra, SG; Yen, T; Keir, ST; Cooter, M; Hoadley, KA; Rasheed, A; Lipp, ES; McLendon, R; Ali-Osman, F; Bigner, DD; Sampson, JH; Kwatra, MM
MLA Citation
Brown, KE, Chagoya, G, Kwatra, SG, Yen, T, Keir, ST, Cooter, M, Hoadley, KA, Rasheed, A, Lipp, ES, McLendon, R, Ali-Osman, F, Bigner, DD, Sampson, JH, and Kwatra, MM. "Proteomic profiling of patient-derived glioblastoma xenografts identifies a subset with activated EGFR: Implications for drug development." Journal of Neurochemistry 133.5 (2015): 730-738.
Source
scival
Published In
Journal of Neurochemistry
Volume
133
Issue
5
Publish Date
2015
Start Page
730
End Page
738
DOI
10.1111/jnc.13032

Mitogen-activated protein kinase (MAPK) hyperactivation and enhanced NRAS expression drive acquired vemurafenib resistance in V600E BRAF melanoma cells.

Although targeting the V600E activating mutation in the BRAF gene, the most common genetic abnormality in melanoma, has shown clinical efficacy in melanoma patients, response is, invariably, short lived. To better understand mechanisms underlying this acquisition of resistance to BRAF-targeted therapy in previously responsive melanomas, we induced vemurafenib resistance in two V600E BRAF+ve melanoma cell lines, A375 and DM443, by serial in vitro vemurafenib exposure. The resulting approximately 10-fold more vemurafenib-resistant cell lines, A375rVem and D443rVem, had higher growth rates and showed differential collateral resistance to cisplatin, melphalan, and temozolomide. The acquisition of vemurafenib resistance was associated with significantly increased NRAS levels in A375rVem and D443rVem, increased activation of the prosurvival protein, AKT, and the MAPKs, ERK, JNK, and P38, which correlated with decreased levels of the MAPK inhibitor protein, GSTP1. Despite the increased NRAS, whole exome sequencing showed no NRAS gene mutations. Inhibition of all three MAPKs and siRNA-mediated NRAS suppression both reversed vemurafenib resistance significantly in A375rVem and DM443rVem. Together, the results indicate a mechanism of acquired vemurafenib resistance in V600E BRAF+ve melanoma cells that involves increased activation of all three human MAPKs and the PI3K pathway, as well as increased NRAS expression, which, contrary to previous reports, was not associated with mutations in the NRAS gene. The data highlight the complexity of the acquired vemurafenib resistance phenotype and the challenge of optimizing BRAF-targeted therapy in this disease. They also suggest that targeting the MAPKs and/or NRAS may provide a strategy to mitigate such resistance in V600E BRAF+ve melanoma.

Authors
Lidsky, M; Antoun, G; Speicher, P; Adams, B; Turley, R; Augustine, C; Tyler, D; Ali-Osman, F
MLA Citation
Lidsky, M, Antoun, G, Speicher, P, Adams, B, Turley, R, Augustine, C, Tyler, D, and Ali-Osman, F. "Mitogen-activated protein kinase (MAPK) hyperactivation and enhanced NRAS expression drive acquired vemurafenib resistance in V600E BRAF melanoma cells." The Journal of biological chemistry 289.40 (October 2014): 27714-27726.
PMID
25063807
Source
epmc
Published In
The Journal of biological chemistry
Volume
289
Issue
40
Publish Date
2014
Start Page
27714
End Page
27726
DOI
10.1074/jbc.m113.532432

Disulfiram is a direct and potent inhibitor of human O6-methylguanine-DNA methyltransferase (MGMT) in brain tumor cells and mouse brain and markedly increases the alkylating DNA damage.

The alcohol aversion drug disulfiram (DSF) reacts and conjugates with the protein-bound nucleophilic cysteines and is known to elicit anticancer effects alone or improve the efficacy of many cancer drugs. We investigated the effects of DSF on human O(6)-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein and chemotherapy target that removes the mutagenic O(6)-akyl groups from guanines, and thus confers resistance to alkylating agents in brain tumors. We used DSF, copper-chelated DSF or CuCl2-DSF combination and found that all treatments inhibited the MGMT activity in two brain tumor cell lines in a rapid and dose-dependent manner. The drug treatments resulted in the loss of MGMT protein from tumor cells through the ubiquitin-proteasome pathway. Evidence showed that Cys145, a reactive cysteine, critical for DNA repair was the sole site of DSF modification in the MGMT protein. DSF was a weaker inhibitor of MGMT, compared with the established O(6)-benzylguanine; nevertheless, the 24-36h suppression of MGMT activity in cell cultures vastly increased the alkylation-induced DNA interstrand cross-linking, G2/M cell cycle blockade, cytotoxicity and the levels of apoptotic markers. Normal mice treated with DSF showed significantly attenuated levels of MGMT activity and protein in the liver and brain tissues. In nude mice bearing T98 glioblastoma xenografts, there was a preferential inhibition of tumor MGMT. Our studies demonstrate a strong and direct inhibition of MGMT by DSF and support the repurposing of this brain penetrating drug for glioma therapy. The findings also imply an increased risk for alkylation damage in alcoholic patients taking DSF.

Authors
Paranjpe, A; Zhang, R; Ali-Osman, F; Bobustuc, GC; Srivenugopal, KS
MLA Citation
Paranjpe, A, Zhang, R, Ali-Osman, F, Bobustuc, GC, and Srivenugopal, KS. "Disulfiram is a direct and potent inhibitor of human O6-methylguanine-DNA methyltransferase (MGMT) in brain tumor cells and mouse brain and markedly increases the alkylating DNA damage." Carcinogenesis 35.3 (March 2014): 692-702.
PMID
24193513
Source
pubmed
Published In
Carcinogenesis
Volume
35
Issue
3
Publish Date
2014
Start Page
692
End Page
702
DOI
10.1093/carcin/bgt366

Endothelial colony forming cells (ECFCs) as a model for studying effects of low-dose ionizing radiation: growth inhibition by a single dose.

Identification of measurable nontransient responses to low-dose radiation in human primary cell cultures remains a problem. To this end, circulating endothelial colony-forming (progenitor) cells (ECFCs) were examined as an experimental model. ECFCs were isolated from three cord blood donors. Cells were positive for endothelial cell markers and remained highly proliferative after long-term cryopreservation. A single dose of X-ray radiation (0.06-0.38 Gy) inhibited ECFC culture growth. This effect was evident at 48 hours and persisted up to 72 hr postirradiation. Such protracted cytostatic response of ECFCs to low-dose radiation suggests that ECFC primary cultures can be used to study low-dose radiation effects.

Authors
Kinev, AV; Levering, V; Young, K; Ali-Osman, F; Truskey, GA; Dewhirst, MW; Il'yasova, D
MLA Citation
Kinev, AV, Levering, V, Young, K, Ali-Osman, F, Truskey, GA, Dewhirst, MW, and Il'yasova, D. "Endothelial colony forming cells (ECFCs) as a model for studying effects of low-dose ionizing radiation: growth inhibition by a single dose." Cancer Invest 31.5 (June 2013): 359-364.
PMID
23621632
Source
pubmed
Published In
Cancer Investigation (Informa)
Volume
31
Issue
5
Publish Date
2013
Start Page
359
End Page
364
DOI
10.3109/07357907.2013.789903

Small ubiquitin-like modifier 1-3 conjugation is activated in human astrocytic brain tumors and is required for glioblastoma cell survival (vol 104, pg 70, 2013)

Authors
Yang, W; Wang, L; Roehn, G; Pearlstein, RD; Ali-Osman, F; Pan, H; Goldbrunner, R; Krantz, M; Harms, C; Paschen, W
MLA Citation
Yang, W, Wang, L, Roehn, G, Pearlstein, RD, Ali-Osman, F, Pan, H, Goldbrunner, R, Krantz, M, Harms, C, and Paschen, W. "Small ubiquitin-like modifier 1-3 conjugation is activated in human astrocytic brain tumors and is required for glioblastoma cell survival (vol 104, pg 70, 2013)." CANCER SCIENCE 104.2 (February 2013): 274-274.
Source
wos-lite
Published In
Cancer Science
Volume
104
Issue
2
Publish Date
2013
Start Page
274
End Page
274
DOI
10.1111/cas.12109

Termination of BRAF Targeted Therapy Augments Tumor Growth in the Setting of Vemurafenib Resistance

Authors
Lidsky, ME; Turley, RS; Speicher, P; Augustine, CK; Ali-Osman, F; Tyler, DS
MLA Citation
Lidsky, ME, Turley, RS, Speicher, P, Augustine, CK, Ali-Osman, F, and Tyler, DS. "Termination of BRAF Targeted Therapy Augments Tumor Growth in the Setting of Vemurafenib Resistance." February 2013.
Source
wos-lite
Published In
Annals of Surgical Oncology
Volume
20
Publish Date
2013
Start Page
S90
End Page
S90

Small ubiquitin-like modifier 1-3 conjugation [corrected] is activated in human astrocytic brain tumors and is required for glioblastoma cell survival.

Small ubiquitin-like modifier (SUMO1-3) constitutes a group of proteins that conjugate to lysine residues of target proteins thereby modifying their activity, stability, and subcellular localization. A large number of SUMO target proteins are transcription factors and other nuclear proteins involved in gene expression. Furthermore, SUMO conjugation plays key roles in genome stability, quality control of newly synthesized proteins, proteasomal degradation of proteins, and DNA damage repair. Any marked increase in levels of SUMO-conjugated proteins is therefore expected to have a major impact on the fate of cells. We show here that SUMO conjugation is activated in human astrocytic brain tumors. Levels of both SUMO1- and SUMO2/3-conjugated proteins were markedly increased in tumor samples. The effect was least pronounced in low-grade astrocytoma (WHO Grade II) and most pronounced in glioblastoma multiforme (WHO Grade IV). We also found a marked rise in levels of Ubc9, the only SUMO conjugation enzyme identified so far. Blocking SUMO1-3 conjugation in glioblastoma cells by silencing their expression blocked DNA synthesis, cell growth, and clonogenic survival of cells. It also resulted in DNA-dependent protein kinase-induced phosphorylation of H2AX, indicative of DNA double-strand damage, and G(2) /M cell cycle arrest. Collectively, these findings highlight the pivotal role of SUMO conjugation in DNA damage repair processes and imply that the SUMO conjugation pathway could be a new target of therapeutic intervention aimed at increasing the sensitivity of glioblastomas to radiotherapy and chemotherapy.

Authors
Yang, W; Wang, L; Roehn, G; Pearlstein, RD; Ali-Osman, F; Pan, H; Goldbrunner, R; Krantz, M; Harms, C; Paschen, W
MLA Citation
Yang, W, Wang, L, Roehn, G, Pearlstein, RD, Ali-Osman, F, Pan, H, Goldbrunner, R, Krantz, M, Harms, C, and Paschen, W. "Small ubiquitin-like modifier 1-3 conjugation [corrected] is activated in human astrocytic brain tumors and is required for glioblastoma cell survival." Cancer Sci 104.1 (January 2013): 70-77.
PMID
23078246
Source
pubmed
Published In
Cancer Science
Volume
104
Issue
1
Publish Date
2013
Start Page
70
End Page
77
DOI
10.1111/cas.12047

Small ubiquitin-like modifier 1-3 is activated in human astrocytic brain tumors and is required for glioblastoma cell survival

Small ubiquitin-like modifier (SUMO1-3) constitutes a group of proteins that conjugate to lysine residues of target proteins thereby modifying their activity, stability, and subcellular localization. A large number of SUMO target proteins are transcription factors and other nuclear proteins involved in gene expression. Furthermore, SUMO conjugation plays key roles in genome stability, quality control of newly synthesized proteins, proteasomal degradation of proteins, and DNA damage repair. Any marked increase in levels of SUMO-conjugated proteins is therefore expected to have a major impact on the fate of cells. We show here that SUMO conjugation is activated in human astrocytic brain tumors. Levels of both SUMO1- and SUMO2/3-conjugated proteins were markedly increased in tumor samples. The effect was least pronounced in low-grade astrocytoma (WHO Grade II) and most pronounced in glioblastoma multiforme (WHO Grade IV). We also found a marked rise in levels of Ubc9, the only SUMO conjugation enzyme identified so far. Blocking SUMO1-3 conjugation in glioblastoma cells by silencing their expression blocked DNA synthesis, cell growth, and clonogenic survival of cells. It also resulted in DNA-dependent protein kinase-induced phosphorylation of H2AX, indicative of DNA double-strand damage, and G2/M cell cycle arrest. Collectively, these findings highlight the pivotal role of SUMO conjugation in DNA damage repair processes and imply that the SUMO conjugation pathway could be a new target of therapeutic intervention aimed at increasing the sensitivity of glioblastomas to radiotherapy and chemotherapy. © 2012 Japanese Cancer Association.

Authors
Yang, W; Wang, L; Roehn, G; Pearlstein, RD; Ali-Osman, F; Pan, H; Goldbrunner, R; Krantz, M; Harms, C; Paschen, W
MLA Citation
Yang, W, Wang, L, Roehn, G, Pearlstein, RD, Ali-Osman, F, Pan, H, Goldbrunner, R, Krantz, M, Harms, C, and Paschen, W. "Small ubiquitin-like modifier 1-3 is activated in human astrocytic brain tumors and is required for glioblastoma cell survival." Cancer Science 104.1 (2013): 70-77.
Source
scival
Published In
Cancer Science
Volume
104
Issue
1
Publish Date
2013
Start Page
70
End Page
77
DOI
10.1111/cas.12047

ADRENOMEDULLIN (ADM) LEVELS IN BONCHOALVEOLAR LAVAGE (BAL) PREDICT VENTILATOR ASSOCIATED PNEUMONIA (VAP) IN PATIENTS WITH A HIGH CLINICAL PULMONARY INFECTION SCORE (CPIS)

Authors
Flores, RD; Rivera, F; Zink, J; Stoeppel, C; Ali-Osman, F; Liu, M-M; Minei, J; Minshall, C
MLA Citation
Flores, RD, Rivera, F, Zink, J, Stoeppel, C, Ali-Osman, F, Liu, M-M, Minei, J, and Minshall, C. "ADRENOMEDULLIN (ADM) LEVELS IN BONCHOALVEOLAR LAVAGE (BAL) PREDICT VENTILATOR ASSOCIATED PNEUMONIA (VAP) IN PATIENTS WITH A HIGH CLINICAL PULMONARY INFECTION SCORE (CPIS)." December 2012.
Source
wos-lite
Published In
Critical Care Medicine
Volume
40
Issue
12
Publish Date
2012
Start Page
U114
End Page
U114

A Phase 2 Trial of Imatinib Mesylate As Maintenance Therapy for Patients with Newly Diagnosed C-Kit Positive Acute Myeloid Leukemia (AML)

Authors
Advani, A; Cooper, B; Sowunmi, O; Elson, P; Ali-Osman, F; Park, J; Rao, A; Rizzieri, DA; Wang, ES; Cotta, C; Sekeres, MA; Kalaycio, M; Sobecks, R; Rouphail, B; Maciejewski, JP; Davis, R; Bailey, L; Foster, B; Rush, ML; Adams, D; Tse, W
MLA Citation
Advani, A, Cooper, B, Sowunmi, O, Elson, P, Ali-Osman, F, Park, J, Rao, A, Rizzieri, DA, Wang, ES, Cotta, C, Sekeres, MA, Kalaycio, M, Sobecks, R, Rouphail, B, Maciejewski, JP, Davis, R, Bailey, L, Foster, B, Rush, ML, Adams, D, and Tse, W. "A Phase 2 Trial of Imatinib Mesylate As Maintenance Therapy for Patients with Newly Diagnosed C-Kit Positive Acute Myeloid Leukemia (AML)." November 16, 2012.
Source
wos-lite
Published In
Blood
Volume
120
Issue
21
Publish Date
2012

Abstract 1177: The mutational status of the p53 tumor suppressor gene is a determinant of GSTP1 expression and mediates GSTP1-dependent drug resistance in human glioblastoma

Authors
Antoun, GR; McLendon, R; Friedman, H; Friedman, A; Bigner, D; Ali-Osman, F
MLA Citation
Antoun, GR, McLendon, R, Friedman, H, Friedman, A, Bigner, D, and Ali-Osman, F. "Abstract 1177: The mutational status of the p53 tumor suppressor gene is a determinant of GSTP1 expression and mediates GSTP1-dependent drug resistance in human glioblastoma." April 15, 2012.
Source
crossref
Published In
Cancer Research
Volume
72
Issue
8 Supplement
Publish Date
2012
Start Page
1177
End Page
1177
DOI
10.1158/1538-7445.AM2012-1177

Abstract 2012: MAP kinase activation and suppression of anti-apoptotic Bcl-2 family members are associated with induction of apoptotic death in melanoma cells following down-regulation of glutathione S-transferase P1

Authors
Turley, RS; Lidsky, ME; Tyler, DS; Ali-Osman, F
MLA Citation
Turley, RS, Lidsky, ME, Tyler, DS, and Ali-Osman, F. "Abstract 2012: MAP kinase activation and suppression of anti-apoptotic Bcl-2 family members are associated with induction of apoptotic death in melanoma cells following down-regulation of glutathione S-transferase P1." Cancer Research 72.8 Supplement (April 15, 2012): 2012-2012.
Source
crossref
Published In
Cancer Research
Volume
72
Issue
8 Supplement
Publish Date
2012
Start Page
2012
End Page
2012
DOI
10.1158/1538-7445.AM2012-2012

Abstract 2162: EGFR-induced interaction of GSTP1 with the SH2-domain of Grb2 enhances Ras downstream activation in human glioma cells

Authors
Okamura, T; Ali-Osman, F
MLA Citation
Okamura, T, and Ali-Osman, F. "Abstract 2162: EGFR-induced interaction of GSTP1 with the SH2-domain of Grb2 enhances Ras downstream activation in human glioma cells." Cancer Research 72.8 Supplement (April 15, 2012): 2162-2162.
Source
crossref
Published In
Cancer Research
Volume
72
Issue
8 Supplement
Publish Date
2012
Start Page
2162
End Page
2162
DOI
10.1158/1538-7445.AM2012-2162

Associations of high-grade glioma with glioma risk alleles and histories of allergy and smoking.

Glioma risk has consistently been inversely associated with allergy history but not with smoking history despite putative biologic plausibility. Data from 855 high-grade glioma cases and 1,160 controls from 4 geographic regions of the United States during 1997-2008 were analyzed for interactions between allergy and smoking histories and inherited variants in 5 established glioma risk regions: 5p15.3 (TERT), 8q24.21 (CCDC26/MLZE), 9p21.3 (CDKN2B), 11q23.3 (PHLDB1/DDX6), and 20q13.3 (RTEL1). The inverse relation between allergy and glioma was stronger among those who did not (odds ratio(allergy-glioma) = 0.40, 95% confidence interval: 0.28, 0.58) versus those who did (odds ratio(allergy-glioma) = 0.76, 95% confidence interval: 0.59, 0.97; P(interaction) = 0.02) carry the 9p21.3 risk allele. However, the inverse association with allergy was stronger among those who carried (odds ratio(allergy-glioma) = 0.44, 95% confidence interval: 0.29, 0.68) versus those who did not carry (odds ratio(allergy-glioma) = 0.68, 95% confidence interval: 0.54, 0.86) the 20q13.3 glioma risk allele, but this interaction was not statistically significant (P = 0.14). No relation was observed between glioma risk and smoking (odds ratio = 0.92, 95% confidence interval: 0.77, 1.10; P = 0.37), and there were no interactions for glioma risk of smoking history with any of the risk alleles. The authors' observations are consistent with a recent report that the inherited glioma risk variants in chromosome regions 9p21.3 and 20q13.3 may modify the inverse association of allergy and glioma.

Authors
Lachance, DH; Yang, P; Johnson, DR; Decker, PA; Kollmeyer, TM; McCoy, LS; Rice, T; Xiao, Y; Ali-Osman, F; Wang, F; Stoddard, SM; Sprau, DJ; Kosel, ML; Wiencke, JK; Wiemels, JL; Patoka, JS; Davis, F; McCarthy, B; Rynearson, AL; Worra, JB; Fridley, BL; O'Neill, BP; Buckner, JC; Il'yasova, D; Jenkins, RB; Wrensch, MR
MLA Citation
Lachance, DH, Yang, P, Johnson, DR, Decker, PA, Kollmeyer, TM, McCoy, LS, Rice, T, Xiao, Y, Ali-Osman, F, Wang, F, Stoddard, SM, Sprau, DJ, Kosel, ML, Wiencke, JK, Wiemels, JL, Patoka, JS, Davis, F, McCarthy, B, Rynearson, AL, Worra, JB, Fridley, BL, O'Neill, BP, Buckner, JC, Il'yasova, D, Jenkins, RB, and Wrensch, MR. "Associations of high-grade glioma with glioma risk alleles and histories of allergy and smoking." Am J Epidemiol 174.5 (September 1, 2011): 574-581.
PMID
21742680
Source
pubmed
Published In
American Journal of Epidemiology
Volume
174
Issue
5
Publish Date
2011
Start Page
574
End Page
581
DOI
10.1093/aje/kwr124

GAIN-OF-FUNCTION tGLI1 TRANSCRIPTION FACTOR AUGMENTS ANCHORAGE-INDEPENDENT GROWTH OF MEDULLOBLASTOMA CELLS AND CONFERS THEIR RESISTANCE TO SMO INHIBITORS

Authors
Cao, X; Zhu, H; Bigner, D; Ali-Osman, F; Lo, H-W
MLA Citation
Cao, X, Zhu, H, Bigner, D, Ali-Osman, F, and Lo, H-W. "GAIN-OF-FUNCTION tGLI1 TRANSCRIPTION FACTOR AUGMENTS ANCHORAGE-INDEPENDENT GROWTH OF MEDULLOBLASTOMA CELLS AND CONFERS THEIR RESISTANCE TO SMO INHIBITORS." May 2011.
Source
wos-lite
Published In
Neuro-Oncology
Volume
13
Publish Date
2011
Start Page
I9
End Page
I9

UPREGULATION OF VEGF-A GENE EXPRESSION BY THE tGLI1 TRANSCRIPTION FACTOR CONTRIBUTES TO GLIOBLASTOMA ANGIOGENESIS

Authors
Zhu, H; Cao, X; Keir, S; Bigner, D; Ali-Osman, F; Lo, H-W
MLA Citation
Zhu, H, Cao, X, Keir, S, Bigner, D, Ali-Osman, F, and Lo, H-W. "UPREGULATION OF VEGF-A GENE EXPRESSION BY THE tGLI1 TRANSCRIPTION FACTOR CONTRIBUTES TO GLIOBLASTOMA ANGIOGENESIS." May 2011.
Source
wos-lite
Published In
Neuro-Oncology
Volume
13
Publish Date
2011
Start Page
I15
End Page
I16

EGFR AND EGFRvIII UNDERGO STRESS- AND EGFR KINASE INHIBITOR-INDUCED MITOCHONDRIAL TRANSLOCALIZATION IN GLIOBLASTOMA: A POTENTIAL MECHANISM OF EGFR- AND EGFRvIII-DRIVEN ANTAGONISM OF APOPTOSIS AND DRUG RESPONSE

Authors
Cao, X; Zhu, H; Bigner, D; Ali-Osman, F; Lo, H-W
MLA Citation
Cao, X, Zhu, H, Bigner, D, Ali-Osman, F, and Lo, H-W. "EGFR AND EGFRvIII UNDERGO STRESS- AND EGFR KINASE INHIBITOR-INDUCED MITOCHONDRIAL TRANSLOCALIZATION IN GLIOBLASTOMA: A POTENTIAL MECHANISM OF EGFR- AND EGFRvIII-DRIVEN ANTAGONISM OF APOPTOSIS AND DRUG RESPONSE." May 2011.
Source
wos-lite
Published In
Neuro-Oncology
Volume
13
Publish Date
2011
Start Page
I8
End Page
I9

Abstract 2337: Defining significance of the novel tGLI1 transcription factor in cancer growth and progression

Authors
Cao, X; Dewhirst, M; Ali-Osman, F; Lo, H-W
MLA Citation
Cao, X, Dewhirst, M, Ali-Osman, F, and Lo, H-W. "Abstract 2337: Defining significance of the novel tGLI1 transcription factor in cancer growth and progression." Cancer Research 71.8 Supplement (April 15, 2011): 2337-2337.
Source
crossref
Published In
Cancer Research
Volume
71
Issue
8 Supplement
Publish Date
2011
Start Page
2337
End Page
2337
DOI
10.1158/1538-7445.AM2011-2337

Abstract 703: GSTP1 inhibition of HSP27 phosphorylation contributes to glioma drug resistance

Authors
Okamura, T; Ali-osman, F
MLA Citation
Okamura, T, and Ali-osman, F. "Abstract 703: GSTP1 inhibition of HSP27 phosphorylation contributes to glioma drug resistance." Cancer Research 71.8 Supplement (April 15, 2011): 703-703.
Source
crossref
Published In
Cancer Research
Volume
71
Issue
8 Supplement
Publish Date
2011
Start Page
703
End Page
703
DOI
10.1158/1538-7445.AM2011-703

Abstract 1635: Short hairpin RNA-mediated transcriptional suppression of glutathione S-transferase P1 suppresses growth and induces apoptosis through altered MAP kinase signaling in melanoma cells

Authors
Turley, RS; Liu, J; Tyler, D; Ali-Osman, F
MLA Citation
Turley, RS, Liu, J, Tyler, D, and Ali-Osman, F. "Abstract 1635: Short hairpin RNA-mediated transcriptional suppression of glutathione S-transferase P1 suppresses growth and induces apoptosis through altered MAP kinase signaling in melanoma cells." Cancer Research 71.8 Supplement (April 15, 2011): 1635-1635.
Source
crossref
Published In
Cancer Research
Volume
71
Issue
8 Supplement
Publish Date
2011
Start Page
1635
End Page
1635
DOI
10.1158/1538-7445.AM2011-1635

EGFR and EGFRvIII undergo stress- and EGFR kinase inhibitor-induced mitochondrial translocalization: a potential mechanism of EGFR-driven antagonism of apoptosis.

BACKGROUND: Epidermal growth factor receptor (EGFR) plays an essential role in normal development, tumorigenesis and malignant biology of human cancers, and is known to undergo intracellular trafficking to subcellular organelles. Although several studies have shown that EGFR translocates into the mitochondria in cancer cells, it remains unclear whether mitochondrially localized EGFR has an impact on the cells and whether EGFRvIII, a constitutively activated variant of EGFR, undergoes mitochondrial transport similar to EGFR. RESULTS: We report that both receptors translocate into the mitochondria of human glioblastoma and breast cancer cells, following treatments with the apoptosis inducers, staurosporine and anisomycin, and with an EGFR kinase inhibitor. Using mutant EGFR/EGFRvIII receptors engineered to undergo enriched intracellular trafficking into the mitochondria, we showed that glioblastoma cells expressing the mitochondrially enriched EGFRvIII were more resistant to staurosporine- and anisomycin-induced growth suppression and apoptosis and were highly resistant to EGFR kinase inhibitor-mediated growth inhibition. CONCLUSIONS: These findings indicate that apoptosis inducers and EGFR-targeted inhibitors enhance mitochondrial translocalization of both EGFR and EGFRvIII and that mitochondrial accumulation of these receptors contributes to tumor drug resistance. The findings also provide evidence for a potential link between the mitochondrial EGFR pathway and apoptosis.

Authors
Cao, X; Zhu, H; Ali-Osman, F; Lo, H-W
MLA Citation
Cao, X, Zhu, H, Ali-Osman, F, and Lo, H-W. "EGFR and EGFRvIII undergo stress- and EGFR kinase inhibitor-induced mitochondrial translocalization: a potential mechanism of EGFR-driven antagonism of apoptosis. (Published online)" Mol Cancer 10 (March 9, 2011): 26-.
PMID
21388543
Source
pubmed
Published In
Molecular Cancer
Volume
10
Publish Date
2011
Start Page
26
DOI
10.1186/1476-4598-10-26

Assessment of type of allergy and antihistamine use in the development of glioma.

BACKGROUND: Allergies have been associated with decreased risk of glioma; but, associations between duration and timing of allergies, and antihistamine use and glioma risk have been less consistent. The objective was to investigate this association by analyzing types, number, years since diagnosis, and age at diagnosis of allergies, and information on antihistamine usage, including type, duration, and frequency of exposure. METHODS: Self-report data on medically diagnosed allergies and antihistamine use were obtained for 419 glioma cases and 612 hospital-based controls from Duke University and NorthShore University HealthSystem. RESULTS: High- and low-grade glioma cases were statistically significantly less likely to report any allergy than controls (OR = 0.66, 95% CI: 0.49-0.87 and OR = 0.44, 95% CI: 0.25-0.76, respectively). The number of types of allergies (seasonal, medication, pet, food, and other) was inversely associated with glioma risk in a dose-response manner (P value for trend < 0.05). Age at diagnosis and years since diagnosis of allergies were not associated with glioma risk. Oral antihistamine use was statistically significantly inversely associated with glioma risk, but when stratified by allergy status, remained significant only for those with high-grade glioma and no medically diagnosed allergy. CONCLUSIONS: All types of allergies appear to be protective with reduced risk for those with more types of allergies. Antihistamine use, other than in relationship with allergy status, may not influence glioma risk. IMPACT: A comprehensive study of allergies and antihistamine use using standardized questions and biological markers will be essential to further delineate the biological mechanism that may be involved in brain tumor development.

Authors
McCarthy, BJ; Rankin, K; Il'yasova, D; Erdal, S; Vick, N; Ali-Osman, F; Bigner, DD; Davis, F
MLA Citation
McCarthy, BJ, Rankin, K, Il'yasova, D, Erdal, S, Vick, N, Ali-Osman, F, Bigner, DD, and Davis, F. "Assessment of type of allergy and antihistamine use in the development of glioma." Cancer Epidemiol Biomarkers Prev 20.2 (February 2011): 370-378.
PMID
21300619
Source
pubmed
Published In
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology
Volume
20
Issue
2
Publish Date
2011
Start Page
370
End Page
378
DOI
10.1158/1055-9965.EPI-10-0948

Association between body mass index and mortality in patients with glioblastoma mutliforme.

PURPOSE: To examine the association between obesity and survival in patients with glioblastoma mutliforme (GBM) METHODS: Using a prospective design, 1,259 patients with previously untreated GBM were recruited between 1991 and 2008. Height and weight were self-reported or abstracted from medical records at study entry and used to calculate body mass index (BMI) [weight (kg)/[height (m)](2). Cox proportional models were used to estimate the risk of death associated with BMI as a continuous variable or categorized using established criteria (normal weight, 18.5-24.9 kg/m(2); overweight, 25.0-29.9 kg/m(2); obese, ≥ 30.0 kg/m(2)). RESULTS: Median follow-up was 40 months, and 1,069 (85%) deaths were observed during this period. For all patients, minimal adjusted analyses indicated no significant association between BMI treated as a continuous variable and survival. Compared with patients with a BMI 18.5-24.9 kg/m(2), the minimally adjusted HR for overall survival was 1.08 (95% CI, 0.94-1.24) for a BMI 25-29.9 kg/m(2) and 1.08 (95% CI, 0.91-28) for a BMI ≥ 30.0 kg/m(2). After additional adjustment for adjuvant therapy, the HR for those with a BMI of 25.0-29.9 kg/m(2) was 1.14 (95% CI, 0.99-1.32) and 1.09 (95% CI, 0.91-1.30) for those with a BMI ≥ 30.0 kg/m(2). No significant interactions were revealed for BMI and any demographic variables. CONCLUSION: BMI was not associated with survival in newly diagnosed and previously untreated patients with GBM. Further research investigating the prognostic significance of alternative, quantitative measures of body habitus, and functional performance are required.

Authors
Jones, LW; Ali-Osman, F; Lipp, E; Marcello, JE; McCarthy, B; McCoy, L; Rice, T; Wrensch, M; Il'yasova, D
MLA Citation
Jones, LW, Ali-Osman, F, Lipp, E, Marcello, JE, McCarthy, B, McCoy, L, Rice, T, Wrensch, M, and Il'yasova, D. "Association between body mass index and mortality in patients with glioblastoma mutliforme." Cancer Causes Control 21.12 (December 2010): 2195-2201.
PMID
20838873
Source
pubmed
Published In
Cancer Causes & Control
Volume
21
Issue
12
Publish Date
2010
Start Page
2195
End Page
2201
DOI
10.1007/s10552-010-9639-x

A Phase II trial of gemcitabine and mitoxantrone for patients with acute myeloid leukemia in first relapse.

INTRODUCTION: We evaluated the complete remission (CR) rate in patients with acute myeloid leukemia (AML) in first relapse treated with fixed-dose-rate gemcitabine and mitoxantrone. In addition, we measured multidrug resistance (MDR) proteins on pretreatment bone marrows and correlated expression with outcome. PATIENTS AND METHODS: The study was performed in a 2-stage design. Pretreatment bone marrows were assayed for the MDR proteins (LRP, MDR1, MRP1, SLC28-29A1/A2, ABCC4/C5, and GSTP1) by immunohistochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR). RESULTS: Only 5 of the first 24 patients (21%) achieved CR; therefore, the study was terminated. Eleven patients (46%) had poor-risk cytogenetics and the median duration of first CR was 7.3 months. Patients had significant expression of the various MDR genes, with 70% of patients expressing moderate to high levels of GSTP1 by immunohistochemistry. Higher sum total of ABCC4 and SLC29A2 expression measured by RT-PCR was associated with not achieving CR (20.6 vs. 12.1; P = .006). In addition, there was a trend for higher expression of the sum total of the 10 MDR genes (measured by RT-PCR) and not achieving CR (P = .06). CONCLUSION: The CR rate in this study was comparable to other regimens used in poor-risk patients. Of interest, ABCC4 and SLC29A2 expression were predictive of achieving CR. The high expression of GSTP1 suggests that this may be a therapeutic target for relapsed AML. Finally, the rapidity and ease of using RT-PCR to quantify MDR in this study may have clinical utility in future trials.

Authors
Advani, AS; Shadman, M; Ali-Osman, F; Barker, A; Rybicki, L; Kalaycio, M; Sekeres, MA; de Castro, CM; Diehl, LF; Moore, JO; Beaven, A; Copelan, E; Sobecks, R; Talea, P; Rizzieri, DA
MLA Citation
Advani, AS, Shadman, M, Ali-Osman, F, Barker, A, Rybicki, L, Kalaycio, M, Sekeres, MA, de Castro, CM, Diehl, LF, Moore, JO, Beaven, A, Copelan, E, Sobecks, R, Talea, P, and Rizzieri, DA. "A Phase II trial of gemcitabine and mitoxantrone for patients with acute myeloid leukemia in first relapse." Clin Lymphoma Myeloma Leuk 10.6 (December 2010): 473-476.
PMID
21156465
Source
pubmed
Published In
Clinical Lymphoma, Myeloma and Leukemia
Volume
10
Issue
6
Publish Date
2010
Start Page
473
End Page
476
DOI
10.3816/CLML.2010.n.082

Serine phosphorylation of glutathione S-transferase P1 (GSTP1) by PKCα enhances GSTP1-dependent cisplatin metabolism and resistance in human glioma cells.

Recently, we reported that the human GSTP1 is phosphorylated and functionally activated by the PKC class of serine/threonine kinases. In this study, we investigated the contribution of this post-translational modification of GSTP1 to tumor cisplatin resistance. Using two malignant glioma cell lines, MGR1 and MGR3, the ability of PKCα-phosphorylated GSTP1 to catalyze the conjugation of cisplatin to glutathione was assessed and correlated with cisplatin sensitivity and cisplatin-induced DNA interstrand cross-links and apoptosis of the cells. The results showed PKCα activation and associated phosphorylation of GSTP1 to correlate significantly with increased glutathionylplatinum formation, decreased DNA interstrand cross-link formation and increased cisplatin resistance. Following PKC activation, the IC(50) of cisplatin increased from 13.63μM to 36.49μM in MGR1 and from 20.75μM to 38.45μM in MGR3. In both cell lines, siRNA-mediated GSTP1 or PKCα transcriptional suppression similarly decreased cisplatin IC(50) and was associated with decreased intracellular levels of glutathionylplatinum metabolite. Combined inhibition/transcriptional suppression of both PKCα and GSTP1 was synergistic in enhancing cisplatin sensitivity. Although, cisplatin-induced apoptosis was associated with the translocation of Bax to mitochondria, release of cytochrome c and caspase-3/7 activation, the levels of relocalized Bax and cytochrome c were significantly greater following GSTP1 knockdown. These results support a mechanism of cisplatin resistance mediated by the PKCα-dependent serine phosphorylation of GSTP1 and its associated increased cisplatin metabolism, and suggest the potential of simultaneous targeting of GSTP1 and PKCα to improve the efficacy of cisplatin therapy.

Authors
Singh, S; Okamura, T; Ali-Osman, F
MLA Citation
Singh, S, Okamura, T, and Ali-Osman, F. "Serine phosphorylation of glutathione S-transferase P1 (GSTP1) by PKCα enhances GSTP1-dependent cisplatin metabolism and resistance in human glioma cells." Biochem Pharmacol 80.9 (November 1, 2010): 1343-1355.
PMID
20654585
Source
pubmed
Published In
Biochemical Pharmacology
Volume
80
Issue
9
Publish Date
2010
Start Page
1343
End Page
1355
DOI
10.1016/j.bcp.2010.07.019

Decoupling of DNA damage response signaling from DNA damages underlies temozolomide resistance in glioblastoma cells.

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor in adults. Current therapy includes surgery, radiation and chemotherapy with temozolomide (TMZ). Major determinants of clinical response to TMZ include methylation status of the O6-methylguanine-DNA methyltransferase (MGMT) promoter and mismatch repair (MMR) status. Though the MGMT promoter is methylated in 45% of cases, for the first nine months of follow-up, TMZ does not change survival outcome. Furthermore, MMR deficiency makes little contribution to clinical resistance, suggesting that there exist unrecognized mechanisms of resistance. We generated paired GBM cell lines whose resistance was attributed to neither MGMT nor MMR. We show that, responding to TMZ, these cells exhibit a decoupling of DNA damage response (DDR) from ongoing DNA damages. They display methylation-resistant synthesis in which ongoing DNA synthesis is not inhibited. They are also defective in the activation of the S and G2 phase checkpoint. DDR proteins ATM, Chk2, MDC1, NBS1 and gammaH2AX also fail to form discrete foci. These results demonstrate that failure of DDR may play an active role in chemoresistance to TMZ. DNA damages by TMZ are repaired by MMR proteins in a futile, reiterative process, which activates DDR signaling network that ultimately leads to the onset of cell death. GBM cells may survive genetic insults in the absence of DDR. We anticipate that our findings will lead to more studies that seek to further define the role of DDR in ultimately determining the fate of a tumor cell in response to TMZ and other DNA methylators.

Authors
Cui, B; Johnson, SP; Bullock, N; Ali-Osman, F; Bigner, DD; Friedman, HS
MLA Citation
Cui, B, Johnson, SP, Bullock, N, Ali-Osman, F, Bigner, DD, and Friedman, HS. "Decoupling of DNA damage response signaling from DNA damages underlies temozolomide resistance in glioblastoma cells." J Biomed Res 24.6 (November 2010): 424-435.
PMID
23554659
Source
pubmed
Published In
Journal of Biomedical Research
Volume
24
Issue
6
Publish Date
2010
Start Page
424
End Page
435
DOI
10.1016/S1674-8301(10)60057-7

UNDERSTANDING AND TARGETING KINASE-INDEPENDENT ACTIVITY OF EGFR AND EGFRVIII TO OVERCOME GBM DRUG RESISTANCE

Authors
Zhu, H; Cao, X; Keir, S; Ali-Osman, F; Lo, H-W
MLA Citation
Zhu, H, Cao, X, Keir, S, Ali-Osman, F, and Lo, H-W. "UNDERSTANDING AND TARGETING KINASE-INDEPENDENT ACTIVITY OF EGFR AND EGFRVIII TO OVERCOME GBM DRUG RESISTANCE." November 2010.
Source
wos-lite
Published In
Neuro-Oncology
Volume
12
Publish Date
2010
Start Page
8
End Page
8

EGFR and EGFRvIII interact with PUMA to inhibit mitochondrial translocalization of PUMA and PUMA-mediated apoptosis independent of EGFR kinase activity.

EGFR and its constitutively activated variant EGFRvIII are linked to glioblastoma resistance to therapy, the mechanisms underlying this association, however, are still unclear. We report that in glioblastoma, EGFR/EGFRvIII paradoxically co-expresses with p53-upregulated modulator of apoptosis (PUMA), a proapoptotic member of the Bcl-2 family of proteins primarily located on the mitochondria. EGFR/EGFRvIII binds to PUMA constitutively and under apoptotic stress, and subsequently sequesters PUMA in the cytoplasm. The EGFR-PUMA interaction is independent of EGFR activation and is sustained under EGFR inhibition. A Bcl-2/Bcl-xL inhibitor that mimics PUMA activity sensitizes EGFR/EGFRvIII-expressing glioblastoma cells to Iressa. Collectively, we uncovered a novel kinase-independent function of EGFR/EGFRvIII that leads to tumor drug resistance.

Authors
Zhu, H; Cao, X; Ali-Osman, F; Keir, S; Lo, H-W
MLA Citation
Zhu, H, Cao, X, Ali-Osman, F, Keir, S, and Lo, H-W. "EGFR and EGFRvIII interact with PUMA to inhibit mitochondrial translocalization of PUMA and PUMA-mediated apoptosis independent of EGFR kinase activity." Cancer Lett 294.1 (August 1, 2010): 101-110.
PMID
20153921
Source
pubmed
Published In
Cancer Letters
Volume
294
Issue
1
Publish Date
2010
Start Page
101
End Page
110
DOI
10.1016/j.canlet.2010.01.028

Inhibition of poly(ADP-ribose) polymerase enhances the effect of chemotherapy in an animal model of regional therapy for the treatment of advanced extremity malignant melanoma.

BACKGROUND: Poly(ADP-ribose) polymerase (PARP) is an important regulator of programmed cell death in response to alkylating agents such as temozolomide (TMZ). The goal of this study was to determine if a systemically administered PARP-inhibitor (INO-1001) could augment the efficacy of TMZ in a rat model of extremity malignant melanoma. MATERIALS AND METHODS: PARP activity was measured in vitro across a panel of 5 human malignant melanoma-derived cell lines. To evaluate tumor response to PARP inhibition in combination with regional isolated limb infusion (ILI) therapy with TMZ, two TMZ-resistant malignant melanoma cell lines were grown as xenografts in the hind limb of rats. INO-1001 (400 mg/kg) was injected intraperitoneally 7 times every 8 hours prior to ILI. Tumor volume was measured for up to 40 days. RESULTS: In vitro inhibition of PARP activity by INO-1001 ranged from 25.5% to 65.6%. In a mismatch repair (MMR)-deficient xenograft, treatment with INO-1001 prior to ILI significantly (P < .04) increased the efficacy of TMZ. The increase in tumor volume at day 40 following TMZ-ILI with INO-1001 was only 22.6% compared with 322.8% with TMZ-ILI alone. In a xenograft that was MMR-proficient and had high levels of O(6)-methylguanine-DNA methyltransferase (MGMT) activity, there was little improvement in TMZ efficacy with INO-1001 treatment. CONCLUSION: The PARP-inhibitor, INO-1001, can enhance the response of TMZ-resistant, MMR-deficient, malignant melanoma xenografts to intra-arterially administered TMZ in a regional treatment model of advanced extremity malignant melanoma.

Authors
Toshimitsu, H; Yoshimoto, Y; Augustine, CK; Padussis, JC; Yoo, JS; Angelica Selim, M; Pruitt, SK; Friedman, HS; Ali-Osman, F; Tyler, DS
MLA Citation
Toshimitsu, H, Yoshimoto, Y, Augustine, CK, Padussis, JC, Yoo, JS, Angelica Selim, M, Pruitt, SK, Friedman, HS, Ali-Osman, F, and Tyler, DS. "Inhibition of poly(ADP-ribose) polymerase enhances the effect of chemotherapy in an animal model of regional therapy for the treatment of advanced extremity malignant melanoma." Ann Surg Oncol 17.8 (August 2010): 2247-2254.
PMID
20182810
Source
pubmed
Published In
Annals of Surgical Oncology
Volume
17
Issue
8
Publish Date
2010
Start Page
2247
End Page
2254
DOI
10.1245/s10434-010-0971-x

Sorafenib, a multikinase inhibitor, enhances the response of melanoma to regional chemotherapy.

Melanoma responds poorly to standard chemotherapy due to its intrinsic chemoresistance. Multiple genetic and molecular defects, including an activating mutation in the BRaf kinase gene, are associated with melanoma, and the resulting alterations in signal transduction pathways regulating proliferation and apoptosis are thought to contribute to its chemoresistance. Sorafenib, a multikinase inhibitor that targets BRaf kinase, is Food and Drug Administration approved for use in advanced renal cell and hepatocellular carcinomas. Although sorafenib has shown little promise as a single agent in melanoma patients, recent clinical trials suggest that, when combined with chemotherapy, it may have more benefit. We evaluated the ability of sorafenib to augment the cytotoxic effects of melphalan, a regional chemotherapeutic agent, and temozolomide, used in systemic and regional treatment of melanoma, on a panel of 24 human melanoma-derived cell lines and in an animal model of melanoma. Marked differences in response to 10 micromol/L sorafenib alone were observed in vitro across cell lines. Response to sorafenib significantly correlated with extracellular signal-regulated kinase (ERK) downregulation and loss of Mcl-1 expression (P < 0.05). Experiments with the mitogen-activated protein kinase/ERK kinase inhibitor U0126 suggest a unique role for ERK downregulation in the observed effects. Sorafenib in combination with melphalan or temozolomide led to significantly improved responses in vitro (P < 0.05). In the animal model of melanoma, sorafenib in combination with regional melphalan or regional temozolomide was more effective than either treatment alone in slowing tumor growth. These results show that sorafenib in combination with chemotherapy provides a novel approach to enhance chemotherapeutic efficacy in the regional treatment of in-transit melanoma.

Authors
Augustine, CK; Toshimitsu, H; Jung, S-H; Zipfel, PA; Yoo, JS; Yoshimoto, Y; Selim, MA; Burchette, J; Beasley, GM; McMahon, N; Padussis, J; Pruitt, SK; Ali-Osman, F; Tyler, DS
MLA Citation
Augustine, CK, Toshimitsu, H, Jung, S-H, Zipfel, PA, Yoo, JS, Yoshimoto, Y, Selim, MA, Burchette, J, Beasley, GM, McMahon, N, Padussis, J, Pruitt, SK, Ali-Osman, F, and Tyler, DS. "Sorafenib, a multikinase inhibitor, enhances the response of melanoma to regional chemotherapy." Mol Cancer Ther 9.7 (July 2010): 2090-2101.
PMID
20571072
Source
pubmed
Published In
Molecular cancer therapeutics
Volume
9
Issue
7
Publish Date
2010
Start Page
2090
End Page
2101
DOI
10.1158/1535-7163.MCT-10-0073

Overcoming drug resistance in mantle cell lymphoma using a combination of dose-dense and intense therapy.

We present a study of the prevalence of genetic polymorphisms and expression of genes encoding the drug-resistance proteins glutathione S-transferases (GSTs) in order to gain insights into the pattern of failure evident in mantle cell lymphoma. We note a high preponderance of genetic alterations conferring resistance to standard chemotherapy in this illness. Concurrent with this investigation, we present a series of patients who were provided dose-dense and intense chemotherapy to circumvent these drug-resistance mechanisms. High responses were noted, though durable remissions were few, indicating non-traditional chemotherapy options are important to investigate in this illness.

Authors
Crout, CA; Koh, L-P; Gockerman, JP; Moore, JO; Decastro, C; Long, GD; Diehl, L; Gasparetto, C; Niedzwiecki, D; Edwards, J; Prosnitz, L; Horwitz, M; Chute, J; Morris, A; Davis, P; Beaven, A; Chao, NJ; Ali-Osman, F; Rizzieri, DA
MLA Citation
Crout, CA, Koh, L-P, Gockerman, JP, Moore, JO, Decastro, C, Long, GD, Diehl, L, Gasparetto, C, Niedzwiecki, D, Edwards, J, Prosnitz, L, Horwitz, M, Chute, J, Morris, A, Davis, P, Beaven, A, Chao, NJ, Ali-Osman, F, and Rizzieri, DA. "Overcoming drug resistance in mantle cell lymphoma using a combination of dose-dense and intense therapy." Cancer Invest 28.6 (July 2010): 654-660.
PMID
20521909
Source
pubmed
Published In
Cancer Investigation (Informa)
Volume
28
Issue
6
Publish Date
2010
Start Page
654
End Page
660
DOI
10.3109/07357901003631015

Gene expression signatures as a guide to treatment strategies for in-transit metastatic melanoma.

In-transit metastatic melanoma, which typically presents as multifocal lesions, provides a unique setting to evaluate the utility of gene signatures for defining optimal regional therapeutic strategies and assessing the efficacy of treatment. The goal of this study was to determine whether a single multifocal lesion is representative of residual tumor burden in terms of gene expression signatures predictive of response to therapy. Using microarray-based gene expression profiling, we examined 55 in-transit melanoma lesions across 29 patients with multifocal disease. Principal component analysis, unsupervised hierarchical clustering, one-way ANOVA, binary regression analysis, and gene signatures predictive of oncogenic pathway activation were used to compare patterns of gene expression across all multifocal lesions from a patient. Patterns of gene expression were highly similar (P < 0.006; average r = 0.979) across pretreatment lesions from a single patient compared with the significantly different patterns observed across patients (P < 0.05). The findings presented in this study show that individual melanoma tumor nodules in patients with multifocal disease harbor similar patterns of gene expression and a single lesion can be used to predict response to chemotherapy, evaluate the activation status of oncogenic signaling pathways, and characterize other aspects of the biology of an individual patient's disease. These results will facilitate the use of gene expression profiling in melanoma regional therapy clinical trials to not only select optimal regional chemotherapeutic agents but to also allow for a more rational identification of candidates for specific targeted therapies and evaluation of their therapeutic efficacy. Mol Cancer Ther; 9(4); 779-90. (c)2010 AACR.

Authors
Augustine, CK; Jung, S-H; Sohn, I; Yoo, JS; Yoshimoto, Y; Olson, JA; Friedman, HS; Ali-Osman, F; Tyler, DS
MLA Citation
Augustine, CK, Jung, S-H, Sohn, I, Yoo, JS, Yoshimoto, Y, Olson, JA, Friedman, HS, Ali-Osman, F, and Tyler, DS. "Gene expression signatures as a guide to treatment strategies for in-transit metastatic melanoma." Mol Cancer Ther 9.4 (April 2010): 779-790.
PMID
20371714
Source
pubmed
Published In
Molecular cancer therapeutics
Volume
9
Issue
4
Publish Date
2010
Start Page
779
End Page
790
DOI
10.1158/1535-7163.MCT-09-0764

Cyclooxygenase-2 is a novel transcriptional target of the nuclear EGFR-STAT3 and EGFRvIII-STAT3 signaling axes.

Emerging evidence indicates a novel mode of epidermal growth factor receptor (EGFR) signaling, notably, one involves EGFR nuclear translocalization and subsequent gene activation. To date, however, the significance of the nuclear EGFR pathway in glioblastoma (GBM) is unknown. Here, we report that EGFR and its constitutively activated variant EGFRvIII undergo nuclear translocalization in GBM cells, in which the former event requires EGF stimulation and the latter is constitutive. To gain insights into the effect of nuclear EGFR on gene expression in GBM, we created isogenic GBM cell lines, namely, U87MG-vector, U87MG-EGFR, and U87MG-EGFRdNLS that, respectively, express the control vector, EGFR, and nuclear entry-defective EGFR with a deletion of the nuclear localization signal (NLS). Microarray analysis shows that 19 genes, including cyclooxygenase-2 (COX-2), to be activated in U87MG-EGFR cells but not in U87MG-EGFRdNLS and U87MG-vector cells. Subsequent validation studies indicate that COX-2 gene is expressed at higher levels in cells with EGFR and EGFRvIII than those with EGFRdNLS and EGFRvIIIdNLS. Nuclear EGFR and its transcriptional cofactor signal transducer and activator of transcription 3 (STAT3) associate with the COX-2 promoter. Increased expression of EGFR/EGFRvIII and activated STAT3 leads to the synergistic activation of the COX-2 promoter. Promoter mutational analysis identified a proximal STAT3-binding site that is required for EGFR/EGFRvIII-STAT3-mediated COX-2 gene activation. In GBM tumors, an association exists between levels of COX-2, EGFR/EGFRvIII, and activated STAT3. Together, these findings indicate the existence of the nuclear EGFR/EGFRvIII signaling pathway in GBM and its functional interaction with STAT3 to activate COX-2 gene expression, thus linking EGFR-STAT3 and EGFRvIII-STAT3 signaling axes to proinflammatory COX-2 mediated pathway.

Authors
Lo, H-W; Cao, X; Zhu, H; Ali-Osman, F
MLA Citation
Lo, H-W, Cao, X, Zhu, H, and Ali-Osman, F. "Cyclooxygenase-2 is a novel transcriptional target of the nuclear EGFR-STAT3 and EGFRvIII-STAT3 signaling axes." Mol Cancer Res 8.2 (February 2010): 232-245.
PMID
20145033
Source
pubmed
Published In
Molecular cancer research : MCR
Volume
8
Issue
2
Publish Date
2010
Start Page
232
End Page
245
DOI
10.1158/1541-7786.MCR-09-0391

GENETIC DIVERSITY ASSOCIATED WITH SURVIVAL IN MALIGNANT GLIOMAS IDENTIFIED BY LINKAGE DISEQUILIBRIUM-BASED ANALYSIS OF HAPLOTYPE BLOCK REGIONS OF DNA REPAIR GENES

Authors
Ali-Osman, F; Owzar, K; Adams, B; Lipp, E; Herdon, J; Illyasova, D; Davis, F; Vick, N; Friedman, A; McClendon, R; Reardon, D; Friedman, H; Weale, M; Bigner, D
MLA Citation
Ali-Osman, F, Owzar, K, Adams, B, Lipp, E, Herdon, J, Illyasova, D, Davis, F, Vick, N, Friedman, A, McClendon, R, Reardon, D, Friedman, H, Weale, M, and Bigner, D. "GENETIC DIVERSITY ASSOCIATED WITH SURVIVAL IN MALIGNANT GLIOMAS IDENTIFIED BY LINKAGE DISEQUILIBRIUM-BASED ANALYSIS OF HAPLOTYPE BLOCK REGIONS OF DNA REPAIR GENES." December 2009.
Source
wos-lite
Published In
Neuro-Oncology
Volume
11
Issue
6
Publish Date
2009
Start Page
891
End Page
891

DIRECT TYROSINE PHOSPHORYLATION OF GSTP1 BY EGFR INDUCES JNK ACTIVATION IN GLIOBLASTOMA CELLS

Authors
Okamura, T; Ali-Osman, F
MLA Citation
Okamura, T, and Ali-Osman, F. "DIRECT TYROSINE PHOSPHORYLATION OF GSTP1 BY EGFR INDUCES JNK ACTIVATION IN GLIOBLASTOMA CELLS." December 2009.
Source
wos-lite
Published In
Neuro-Oncology
Volume
11
Issue
6
Publish Date
2009
Start Page
894
End Page
894

A novel splice variant of GLI1 that promotes glioblastoma cell migration and invasion.

The family of GLI zinc finger transcription factors regulates the expression of genes involved in many important cellular processes, notably embryonal development and cellular differentiation. The glioma-associated oncogene homologue 1 (GLI1) isoform, in particular, has attracted much attention because of its frequent activation in many human cancers and its interactions with other signaling pathways, such as those mediated by K-RAS, transforming growth factor-beta, epidermal growth factor receptor, and protein kinase A. Here, we report the identification of a novel truncated GLI1 splice variant, tGLI1, with an in-frame deletion of 123 bases (41 codons) spanning the entire exon 3 and part of exon 4 of the GLI1 gene. Expression of tGLI1 is undetectable in normal cells but is high in glioblastoma multiforme (GBM) and other cancer cells. Although tGLI1 undergoes nuclear translocalization and transactivates GLI1-binding sites similar to GLI1, unlike GLI1, it is associated with increased motility and invasiveness of GBM cells. Using microarray analysis, we showed >100 genes to be differentially expressed in tGLI1-expressing compared with GLI1-expressing GBM cells, although both cell types expressed equal levels of known GLI1-regulated genes, such as PTCH1. We further showed one of the tGLI1 up-regulated genes, CD24, an invasion-associated gene, to be required for the migratory and invasive phenotype of GBM cells. These data provide conclusive evidence for a novel gain-of-function GLI1 splice variant that promotes migration and invasiveness of GBM cells and open up a new research paradigm on the role of the GLI1 pathway in malignancy.

Authors
Lo, H-W; Zhu, H; Cao, X; Aldrich, A; Ali-Osman, F
MLA Citation
Lo, H-W, Zhu, H, Cao, X, Aldrich, A, and Ali-Osman, F. "A novel splice variant of GLI1 that promotes glioblastoma cell migration and invasion." Cancer Res 69.17 (September 1, 2009): 6790-6798.
PMID
19706761
Source
pubmed
Published In
Cancer Research
Volume
69
Issue
17
Publish Date
2009
Start Page
6790
End Page
6798

Tyrosine phosphorylation of the human glutathione S-transferase P1 by epidermal growth factor receptor.

Epidermal growth factor receptor (EGFR) gene amplification, mutations, and/or aberrant activation are frequent abnormalities in malignant gliomas and other human cancers and have been associated with an aggressive clinical course and a poor therapeutic outcome. Elevated glutathione S-transferase P1 (GSTP1), a major drug-metabolizing and stress response signaling protein, is also associated with drug resistance and poor clinical outcome in gliomas and other cancers. Here, we provide evidence that GSTP1 is a downstream EGFR target and that EGFR binds to and phosphorylates tyrosine residues in the GSTP1 protein in vitro and in vivo. Mass spectrometry and mutagenesis analyses in a cell-free system and in gliomas cells identified Tyr-7 and Tyr-198 as major EGFR-specific phospho-acceptor residues in the GSTP1 protein. The phosphorylation increased GSTP1 enzymatic activity significantly, and computer-based modeling showed a corresponding increase in electronegativity of the GSTP1 active site. In human glioma and breast cancer cells, epidermal growth factor stimulation rapidly increased GSTP1 tyrosine phosphorylation and decreased cisplatin sensitivity. Lapatinib, a clinically active EGFR inhibitor, significantly reversed the epidermal growth factor-induced cisplatin resistance. These data define phosphorylation and activation of GSTP1 by EGFR as a novel, heretofore unrecognized component of the EGFR signaling network and a novel mechanism of tumor drug resistance, particularly in tumors with elevated GSTP1 and/or activated EGFR.

Authors
Okamura, T; Singh, S; Buolamwini, J; Haystead, T; Friedman, H; Bigner, D; Ali-Osman, F
MLA Citation
Okamura, T, Singh, S, Buolamwini, J, Haystead, T, Friedman, H, Bigner, D, and Ali-Osman, F. "Tyrosine phosphorylation of the human glutathione S-transferase P1 by epidermal growth factor receptor." J Biol Chem 284.25 (June 19, 2009): 16979-16989.
PMID
19254954
Source
pubmed
Published In
The Journal of biological chemistry
Volume
284
Issue
25
Publish Date
2009
Start Page
16979
End Page
16989
DOI
10.1074/jbc.M808153200

Bifunctional DNA alkylator 1,3-bis(2-chloroethyl)-1-nitrosourea activates the ATR-Chk1 pathway independently of the mismatch repair pathway.

The presence of DNA damage initiates signaling through the ataxia-telangiectasia mutated kinase (ATM) and the ATM- and the Rad3-related kinase (ATR), which phosphorylate, thus activating, the checkpoint kinases (Chk) 1 and 2, which leads to cell cycle arrest. The bifunctional DNA alkylator 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) is cytotoxic primarily by inducing DNA monoadducts and ultimately, interstrand cross-links, which block DNA replication. In this study, we investigated the activation of the ATR-Chk1 pathway in response to BCNU treatment and the dependence of this response on the DNA mismatch repair (MMR) capacity. Medulloblastoma cells were exposed to low and moderate doses of BCNU, and the effects on this DNA damage signaling pathway were examined. In response to BCNU, Chk1 was found to be phosphorylated at serine 345 and exhibited increased kinase activity. Caffeine and wortmannin, which are broad-spectrum inhibitors of ATM and ATR, reduced this phosphorylation. Cell cycle analysis further revealed an accumulation of cells in the S phase in response to BCNU, an effect that was attenuated by caffeine. Small interfering RNA knockdown of ATR also reduced Chk1 phosphorylation after exposure to BCNU. However, knockdown of ATM had no effect on the observed Chk1 phosphorylation, suggesting that ATR was primarily responsible for Chk1 activation. Analysis of Chk1 activation in cells deficient in MMR proteins MutLalpha or MutSalpha indicated that the DNA damage response induced by BCNU was independent of the MMR apparatus. This MMR-independent activation seems to be the result of DNA interstrand cross-link formation.

Authors
Cui, B; Johnson, SP; Bullock, N; Ali-Osman, F; Bigner, DD; Friedman, HS
MLA Citation
Cui, B, Johnson, SP, Bullock, N, Ali-Osman, F, Bigner, DD, and Friedman, HS. "Bifunctional DNA alkylator 1,3-bis(2-chloroethyl)-1-nitrosourea activates the ATR-Chk1 pathway independently of the mismatch repair pathway." Mol Pharmacol 75.6 (June 2009): 1356-1363.
PMID
19261750
Source
pubmed
Published In
Molecular pharmacology
Volume
75
Issue
6
Publish Date
2009
Start Page
1356
End Page
1363
DOI
10.1124/mol.108.053124

EGFR and EGFRvIII attenuate drug-induced apoptosis in glioblastomas via mitochondrial transport and interaction with pro-apoptotic proteins:A novel EGFR/EGFRvIII-mediated mechanism in drug resistance

Authors
Zhu, H; Cao, X; Aldrich, A; Ali-Osman, F; Lo, H-W
MLA Citation
Zhu, H, Cao, X, Aldrich, A, Ali-Osman, F, and Lo, H-W. "EGFR and EGFRvIII attenuate drug-induced apoptosis in glioblastomas via mitochondrial transport and interaction with pro-apoptotic proteins:A novel EGFR/EGFRvIII-mediated mechanism in drug resistance." CANCER RESEARCH 69 (May 1, 2009).
Source
wos-lite
Published In
Cancer Research
Volume
69
Publish Date
2009

Structural and functional analysis of Nucleophosmin I (NPM1) in human malignant gliomas

Authors
Antoun, G; Ali-Osman, F
MLA Citation
Antoun, G, and Ali-Osman, F. "Structural and functional analysis of Nucleophosmin I (NPM1) in human malignant gliomas." CANCER RESEARCH 69 (May 1, 2009).
Source
wos-lite
Published In
Cancer Research
Volume
69
Publish Date
2009

Phosphorylation of a C-terminal tyrosine of GSTP1 by EGFR dissociates GSTP1 from the GSTP1-JNK complex leading to JNK activation in glioblastoma cells

Authors
Okamura, T; Ali-Osman, F
MLA Citation
Okamura, T, and Ali-Osman, F. "Phosphorylation of a C-terminal tyrosine of GSTP1 by EGFR dissociates GSTP1 from the GSTP1-JNK complex leading to JNK activation in glioblastoma cells." CANCER RESEARCH 69 (May 1, 2009).
Source
wos-lite
Published In
Cancer Research
Volume
69
Publish Date
2009

Serine-phosphorylation of the GSTP1 protein by PKC\#945; increase GSTP1-mediated cisplatin metabolism and descrease cisplatin-induced DNA interstrand cross link formation and cisplatin sensitivity in human glioma cells

Authors
Singh, S; Ali-Osman, F
MLA Citation
Singh, S, and Ali-Osman, F. "Serine-phosphorylation of the GSTP1 protein by PKC\#945; increase GSTP1-mediated cisplatin metabolism and descrease cisplatin-induced DNA interstrand cross link formation and cisplatin sensitivity in human glioma cells." CANCER RESEARCH 69 (May 1, 2009).
Source
wos-lite
Published In
Cancer Research
Volume
69
Publish Date
2009

Association between glioma and history of allergies, asthma, and eczema: a case-control study with three groups of controls.

Because glioma etiology is largely unknown, the inverse association of glioma risk with atopic conditions is promising and deserves close scrutiny. We examined the association between a history of allergies, asthma, and eczema, and glioma risk using sibling, friend, and clinic-based controls. This analysis included 388 incident glioma cases and 80 sibling, 191 friend, and 177 clinic-based controls. Each subject's medical history was assessed via a Web-based or telephone survey. Odds ratios (OR) and their 95% confidence intervals (CI) for the associations with allergies, asthma, eczema, and the overall number of these conditions were calculated from conditional (for sibling and friend controls) and unconditional (for clinic-based controls) logistic models. Allergies were consistently inversely associated with the glioma: ORs were 0.53 (95% CI, 0.15-1.84), 0.54 (95% CI, 0.28-1.07), and 0.34 (95% CI, 0.23-0.50) with sibling, friend, and clinic-based controls, respectively. Asthma showed an inverse association only in the comparison with sibling controls (OR, 0.43; 95% CI, 0.19-1.00). Eczema showed an inverse association only in the comparison with friend controls (OR, 0.42; 95% CI, 0.15-1.18). The overall number of these conditions (ordinal score 0, 1, 2, 3) was inversely associated with glioma: The risk decreased 31% to 45% with each addition of an atopic condition. These estimates were the most stable when different control groups were considered. Comparing the prevalence of these conditions in the three control groups with published data, we note that clinic-based controls generally better approximate the prevalence data for population-based groups. These controls seem to present a reasonable choice for clinic-centered case-control studies.

Authors
Il'yasova, D; McCarthy, B; Marcello, J; Schildkraut, JM; Moorman, PG; Krishnamachari, B; Ali-Osman, F; Bigner, DD; Davis, F
MLA Citation
Il'yasova, D, McCarthy, B, Marcello, J, Schildkraut, JM, Moorman, PG, Krishnamachari, B, Ali-Osman, F, Bigner, DD, and Davis, F. "Association between glioma and history of allergies, asthma, and eczema: a case-control study with three groups of controls." Cancer Epidemiol Biomarkers Prev 18.4 (April 2009): 1232-1238.
PMID
19336556
Source
pubmed
Published In
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology
Volume
18
Issue
4
Publish Date
2009
Start Page
1232
End Page
1238
DOI
10.1158/1055-9965.EPI-08-0995

EGF RECEPTOR TYROSINE KINASE MEDIATES A NOVEL PATHWAY OF DRUG RESISTANCE IN MALIGNANT GLIOMAS VIA TYROSINE PHOSPHORYLATION AND FUNCTIONAL ACTIVATION OF GLUTATHIONE S-TRANSFERASE P1

Authors
Okamura, T; Singh, S; Buolamwini, JK; Friedman, HS; Bigner, DD; Ali-Osman, F
MLA Citation
Okamura, T, Singh, S, Buolamwini, JK, Friedman, HS, Bigner, DD, and Ali-Osman, F. "EGF RECEPTOR TYROSINE KINASE MEDIATES A NOVEL PATHWAY OF DRUG RESISTANCE IN MALIGNANT GLIOMAS VIA TYROSINE PHOSPHORYLATION AND FUNCTIONAL ACTIVATION OF GLUTATHIONE S-TRANSFERASE P1." NEURO-ONCOLOGY 11.2 (April 2009): 218-218.
Source
wos-lite
Published In
Neuro-Oncology
Volume
11
Issue
2
Publish Date
2009
Start Page
218
End Page
218

Genomic and molecular profiling predicts response to temozolomide in melanoma.

PURPOSE: Despite objective response rates of only approximately 13%, temozolomide remains one of the most effective single chemotherapy agents against metastatic melanoma, second only to dacarbazine, the current standard of care for systemic treatment of melanoma. The goal of this study was to identify molecular and/or genetic markers that correlate with, and could be used to predict, response to temozolomide-based treatment regimens and that reflect the intrinsic properties of a patient's tumor. EXPERIMENTAL DESIGN: Using a panel of 26 human melanoma-derived cell lines, we determined in vitro temozolomide sensitivity, O(6)-methylguanine-DNA methyltransferase (MGMT) activity, MGMT protein expression and promoter methylation status, and mismatch repair proficiency, as well as the expression profile of 38,000 genes using an oligonucleotide-based microarray platform. RESULTS: The results showed a broad spectrum of temozolomide sensitivity across the panel of cell lines, with IC(50) values ranging from 100 micromol/L to 1 mmol/L. There was a significant correlation between measured temozolomide sensitivity and a gene expression signature-derived prediction of temozolomide sensitivity (P < 0.005). Notably, MGMT alone showed a significant correlation with temozolomide sensitivity (MGMT activity, P < 0.0001; MGMT expression, P

Authors
Augustine, CK; Yoo, JS; Potti, A; Yoshimoto, Y; Zipfel, PA; Friedman, HS; Nevins, JR; Ali-Osman, F; Tyler, DS
MLA Citation
Augustine, CK, Yoo, JS, Potti, A, Yoshimoto, Y, Zipfel, PA, Friedman, HS, Nevins, JR, Ali-Osman, F, and Tyler, DS. "Genomic and molecular profiling predicts response to temozolomide in melanoma." Clin Cancer Res 15.2 (January 15, 2009): 502-510.
PMID
19147755
Source
pubmed
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
15
Issue
2
Publish Date
2009
Start Page
502
End Page
510
DOI
10.1158/1078-0432.CCR-08-1916

Correction: Article on genomic and molecular profiling to predict response to temozolomide (Clinical Cancer Research (2009) 15, (502-510))

Authors
Augustine, CK; Yoo, JS; Potti, A; Yoshimoto, Y; Zipfel, PA; Friedman, HS; Nevins, JR; Ali-Osman, F; Tyler, DS
MLA Citation
Augustine, CK, Yoo, JS, Potti, A, Yoshimoto, Y, Zipfel, PA, Friedman, HS, Nevins, JR, Ali-Osman, F, and Tyler, DS. "Correction: Article on genomic and molecular profiling to predict response to temozolomide (Clinical Cancer Research (2009) 15, (502-510))." Clinical Cancer Research 15.9 (2009): 3240--.
Source
scival
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
15
Issue
9
Publish Date
2009
Start Page
3240-
DOI
10.1158/1078-0432.CCR-15-9-COR

Constitutively activated STAT3 frequently coexpresses with epidermal growth factor receptor in high-grade gliomas and targeting STAT3 sensitizes them to Iressa and alkylators.

PURPOSE: The goals of this study are to elucidate the relationship of the oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) with glioma aggressiveness and to understand the role of high STAT3 activity in the resistance of malignant gliomas and medulloblastomas to chemotherapy. EXPERIMENTAL DESIGN: Immunohistochemical staining and biochemical methods were used to examine the extent of STAT3 activation and EGFR expression in primary specimens and cell lines, respectively. Cellular response to drug treatments was determined using cell cytotoxicity and clonogenic growth assays. RESULTS: We found STAT3 to be constitutively activated in 60% of primary high-grade/malignant gliomas and the extent of activation correlated positively with glioma grade. High levels of activated/phosphorylated STAT3 were also present in cultured human malignant glioma and medulloblastoma cells. Three STAT3-activating kinases, Janus-activated kinase 2 (JAK2), EGFR, and EGFRvIII, contributed to STAT3 activation. An inhibitor to JAK2/STAT3, JSI-124, significantly reduced expression of STAT3 target genes, suppressed cancer cell growth, and induced apoptosis. Furthermore, we found that STAT3 constitutive activation coexisted with EGFR expression in 27.2% of primary high-grade/malignant gliomas and such coexpression correlated positively with glioma grade. Combination of an anti-EGFR agent Iressa and a JAK2/STAT3 inhibitor synergistically suppressed STAT3 activation and potently killed glioblastoma cell lines that expressed EGFR or EGFRvIII. JSI-124 also sensitized malignant glioma and medulloblastoma cells to temozolomide, 1,3-bis(2-chloroethyl)-1-nitrosourea, and cisplatin in which a synergism existed between JSI-124 and cisplatin. CONCLUSION: STAT3 constitutive activation, alone and in concurrence with EGFR expression, plays an important role in high-grade/malignant gliomas and targeting STAT3/JAK2 sensitizes these tumors to anti-EGFR and alkylating agents.

Authors
Lo, H-W; Cao, X; Zhu, H; Ali-Osman, F
MLA Citation
Lo, H-W, Cao, X, Zhu, H, and Ali-Osman, F. "Constitutively activated STAT3 frequently coexpresses with epidermal growth factor receptor in high-grade gliomas and targeting STAT3 sensitizes them to Iressa and alkylators." Clin Cancer Res 14.19 (October 1, 2008): 6042-6054.
PMID
18829483
Source
pubmed
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
14
Issue
19
Publish Date
2008
Start Page
6042
End Page
6054
DOI
10.1158/1078-0432.CCR-07-4923

IDENTIFICATION AND FUNCTIONAL CHARACTERIZATION OF THE HUMAN GSTP1 GENE AS A NOVEL TRANSCRIPTIONAL TARGET OF THE P53 TUMOR SUPPRESSOR GENE

Authors
Lo, H-W; Stephenson, L; Cao, X; Pollock, R; Milas, M; Ali-Osman, F
MLA Citation
Lo, H-W, Stephenson, L, Cao, X, Pollock, R, Milas, M, and Ali-Osman, F. "IDENTIFICATION AND FUNCTIONAL CHARACTERIZATION OF THE HUMAN GSTP1 GENE AS A NOVEL TRANSCRIPTIONAL TARGET OF THE P53 TUMOR SUPPRESSOR GENE." October 2008.
Source
wos-lite
Published In
Neuro-Oncology
Volume
10
Issue
5
Publish Date
2008
Start Page
766
End Page
766

LIGAND-DEPENDENT ACTIVATION OF THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR) INDUCES EARLY DRUG RESISTANCE IN BRAIN TUMOR CELLS VIA ACTIVATION OF ITS DOWNSTREAM TARGET GLUTATHIONE S-TRANSFERASE P1

Authors
Okamura, T; Singh, S; Bigner, D; Ali-Osman, F
MLA Citation
Okamura, T, Singh, S, Bigner, D, and Ali-Osman, F. "LIGAND-DEPENDENT ACTIVATION OF THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR) INDUCES EARLY DRUG RESISTANCE IN BRAIN TUMOR CELLS VIA ACTIVATION OF ITS DOWNSTREAM TARGET GLUTATHIONE S-TRANSFERASE P1." October 2008.
Source
wos-lite
Published In
Neuro-Oncology
Volume
10
Issue
5
Publish Date
2008
Start Page
782
End Page
782

CONSTITUTIVE STAT3 ACTIVATION FREQUENTLY COEXISTS WITH EGFR EXPRESSION IN HIGH-GRADE GLIOMAS AND TARGETING STAT3 SENSITIZES THEM TO ANTI-EGFR AND ALKYLATING AGENTS

Authors
Lo, H-W; Cao, X; Zhu, H; Ali-Osman, F
MLA Citation
Lo, H-W, Cao, X, Zhu, H, and Ali-Osman, F. "CONSTITUTIVE STAT3 ACTIVATION FREQUENTLY COEXISTS WITH EGFR EXPRESSION IN HIGH-GRADE GLIOMAS AND TARGETING STAT3 SENSITIZES THEM TO ANTI-EGFR AND ALKYLATING AGENTS." October 2008.
Source
wos-lite
Published In
Neuro-Oncology
Volume
10
Issue
5
Publish Date
2008
Start Page
766
End Page
766

Mismatch repair deficiency does not mediate clinical resistance to temozolomide in malignant glioma.

PURPOSE: A major mechanism of resistance to methylating agents, including temozolomide, is the DNA repair protein O(6)-alkylguanine-DNA alkyltransferase (AGT). Preclinical data indicates that defective DNA mismatch repair (MMR) results in tolerance to temozolomide regardless of AGT activity. The purpose of this study was to determine the role of MMR deficiency in mediating resistance in samples from patients with both newly diagnosed malignant gliomas and those who have failed temozolomide therapy. EXPERIMENTAL DESIGN: The roles of AGT and MMR deficiency in mediating resistance in glioblastoma multiforme were assessed by immunohistochemistry and microsatellite instability (MSI), respectively. The mutation status of the MSH6 gene, a proposed correlate of temozolomide resistance, was determined by direct sequencing and compared with data from immunofluorescent detection of MSH6 protein and reverse transcription-PCR amplification of MSH6 RNA. RESULTS: Seventy percent of newly diagnosed and 78% of failed-therapy glioblastoma multiforme samples expressed nuclear AGT protein in > or = 20% of cells analyzed, suggesting alternate means of resistance in 20% to 30% of cases. Single loci MSI was observed in 3% of patient samples; no sample showed the presence of high MSI. MSI was not shown to correlate with MSH6 mutation or loss of MSH6 protein expression. CONCLUSIONS: Although high AGT levels may mediate resistance in a portion of these samples, MMR deficiency does not seem to be responsible for mediating temozolomide resistance in adult malignant glioma. Accordingly, the presence of a fraction of samples exhibiting both low AGT expression and MMR proficiency suggests that additional mechanisms of temozolomide resistance are operational in the clinic.

Authors
Maxwell, JA; Johnson, SP; McLendon, RE; Lister, DW; Horne, KS; Rasheed, A; Quinn, JA; Ali-Osman, F; Friedman, AH; Modrich, PL; Bigner, DD; Friedman, HS
MLA Citation
Maxwell, JA, Johnson, SP, McLendon, RE, Lister, DW, Horne, KS, Rasheed, A, Quinn, JA, Ali-Osman, F, Friedman, AH, Modrich, PL, Bigner, DD, and Friedman, HS. "Mismatch repair deficiency does not mediate clinical resistance to temozolomide in malignant glioma." Clin Cancer Res 14.15 (August 1, 2008): 4859-4868.
PMID
18676759
Source
pubmed
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
14
Issue
15
Publish Date
2008
Start Page
4859
End Page
4868
DOI
10.1158/1078-0432.CCR-07-4807

Aberrant NF-kappaB activity is critical in focal necrosis formation of human glioblastoma by regulation of the expression of tissue factor.

Focal necrosis is a key pathologic feature that distinguishes glioblastoma from lower grade glioma. The presence of necrosis in a glioblastoma could promote its rapid growth and clinical progression. Focal necrosis of glioblastoma seems to be associated with thrombosis that result from hyper-coagulability. In the present study, we found that glioblastoma cells had a high level of constitutive nuclear factor (NF)-kappaB activity, which was directly correlated with necrosis in glioblastomas. We also found a direct correlation between NF-kappaB activity and the expression of tissue factor (TF), a potent procoagulant factor in gliomas. Inhibition of TF by an inhibitory antibody prevented the procoagulant activity of glioblastoma cells, indicating a TF-dependent mechanism. Blockade of NF-kappaB activation significantly inhibited TF expression and the procoagulant activity of glioblastoma cells in vitro. Blockade of NF-kappaB activation also significantly inhibited in vivo expression of TF, which was directly correlated with decreased necrosis formation and tumor growth of glioblastoma cells in nude mice. Collectively, these results suggest that elevated NF-kappaB activity in glioblastomas cells plays a critical role in necrosis formation of glioblastoma and that inhibition of NF-kappaB activity in glioblastoma can suppress necrosis formation and progressive growth.

Authors
Xie, T-X; Aldape, KD; Gong, W; Kanzawa, T; Suki, D; Kondo, S; Lang, F; Ali-Osman, F; Sawaya, R; Huang, S
MLA Citation
Xie, T-X, Aldape, KD, Gong, W, Kanzawa, T, Suki, D, Kondo, S, Lang, F, Ali-Osman, F, Sawaya, R, and Huang, S. "Aberrant NF-kappaB activity is critical in focal necrosis formation of human glioblastoma by regulation of the expression of tissue factor." Int J Oncol 33.1 (July 2008): 5-15.
PMID
18575745
Source
pubmed
Published In
International journal of oncology
Volume
33
Issue
1
Publish Date
2008
Start Page
5
End Page
15

Gene expression signatures as a guide to treatment strategies for in-transit metastatic melanoma.

9077 Background: In an era of targeted therapeutics biopsies are increasingly used to personalize cancer treatment. The utility of a single biopsy from a melanoma patient with multifocal disease to define the characteristics of that patient's tumor is unclear. The aim of this study was to evaluate the genetic and molecular relationship of multifocal lesions and determine if one lesion is representative of residual tumor burden. METHODS: Expression across 38k genes was measured using GeneChip microarrays. Binary regression, unsupervised hierarchical clustering, principal component analysis (PCA) and analysis of variance (ANOVA) were used to evaluate the patterns of expression across lesions. Predictions of sensitivity to chemotherapy and oncogenic signaling pathway activation were evaluated using signatures derived from the NCI-60 panel of cancer cell lines. RESULTS: 43 in-transit lesions were obtained from 17 different patients with multifocal extremity melanoma. PCA and unsupervised hierarchical clustering showed distinctly different patterns of gene expression across patients but significantly correlated (average r = 0.979) patterns within a patient. Sensitivity to melphalan and temozolomide was evaluated using defined gene signatures. Predictions across multifocal lesions were significantly correlated within an individual patient (ANOVA p-value: <0.001) and significantly different across patients (p<0.05). Similarly, predicted patterns of gene expression across 6 signaling pathways (Src, PI3K, Ras, Myc, E2F and β-catenin) were significantly correlated within but not across patients (p<0.0001 to 0.0006). CONCLUSIONS: Individual melanoma tumor nodules in patients with multifocal disease are similar and can be used to predict chemosensitivity, genetically characterize a patient's disease and evaluate the activation status of oncogenic signaling pathways. These findings will facilitate the application of microarray-based gene expression profiling in clinical melanoma trials, allowing for a more rational way to identify candidates for specific targeted therapies, and demonstrate that single biopsies obtained for correlative science studies are representative of residual tumor burden. No significant financial relationships to disclose.

Authors
Augustine, CK; Jung, S; Potti, A; Sohn, I; Yoo, JS; Zipfel, P; Olson, J; Ali-Osman, F; Nevins, JR; Tyler, DS
MLA Citation
Augustine, CK, Jung, S, Potti, A, Sohn, I, Yoo, JS, Zipfel, P, Olson, J, Ali-Osman, F, Nevins, JR, and Tyler, DS. "Gene expression signatures as a guide to treatment strategies for in-transit metastatic melanoma." J Clin Oncol 26.15_suppl (May 20, 2008): 9077-.
PMID
27950874
Source
pubmed
Published In
Journal of Clinical Oncology
Volume
26
Issue
15_suppl
Publish Date
2008
Start Page
9077

Gene expression signatures as a guide to treatment strategies for in-transit metastatic melanoma

Authors
Augustine, CK; Jung, S; Potti, A; Sohn, I; Yoo, JS; Zipfel, P; Jr, OJ; Ali-Osman, F; Nevins, JR; Tyler, DS
MLA Citation
Augustine, CK, Jung, S, Potti, A, Sohn, I, Yoo, JS, Zipfel, P, Jr, OJ, Ali-Osman, F, Nevins, JR, and Tyler, DS. "Gene expression signatures as a guide to treatment strategies for in-transit metastatic melanoma." JOURNAL OF CLINICAL ONCOLOGY 26.15 (May 20, 2008).
Source
wos-lite
Published In
Journal of Clinical Oncology
Volume
26
Issue
15
Publish Date
2008

Identification and functional characterization of the human glutathione S-transferase P1 gene as a novel transcriptional target of the p53 tumor suppressor gene.

The glutathione S-transferase P1 (GSTP1) is involved in multiple cellular functions, including phase II metabolism, stress response, signaling, and apoptosis. The mechanisms underlying the significantly high GSTP1 expression in many human tumors are, however, currently not well understood. We report here that the GSTP1 gene is a heretofore unrecognized downstream transcriptional target of the tumor suppressor p53. We identified a p53-binding motif comprising two consecutive half-sites located in intron 4 of the GSTP1 gene and is highly homologous to consensus p53-binding motifs in other p53-responsive genes. Using a combination of electrophoretic mobility shift assay and DNase I footprinting analyses, we showed that wild-type p53 protein binds to the GSTP1 p53 motif and luciferase reporter assays showed the motif to be transcriptionally functional in human tumor cells. In a temperature-sensitive p53-mutant cells, levels of both p21/WAF1 and GSTP1 gene transcripts increased time dependently when cells were switched from the inactive mutant state to the wild-type p53 state. Small interfering RNA-mediated reduction of p53 expression resulted in a specific decrease in GSTP1 expression and in tumor cells with mutated p53; adenovirally mediated expression of wild-type p53 increased GSTP1 expression significantly. In a panel of early-passage brain tumor cultures from patients, high levels of GSTP1 transcripts and protein were associated with wild-type p53 and, conversely, low GSTP1 levels with mutant p53. p53 expression knockdown by small interfering RNA increased cisplatin sensitivity. The ability of wild-type p53 to transcriptionally activate the human GSTP1 gene defines a novel mechanism of protecting the genome and, potentially, of tumor drug resistance.

Authors
Lo, H-W; Stephenson, L; Cao, X; Milas, M; Pollock, R; Ali-Osman, F
MLA Citation
Lo, H-W, Stephenson, L, Cao, X, Milas, M, Pollock, R, and Ali-Osman, F. "Identification and functional characterization of the human glutathione S-transferase P1 gene as a novel transcriptional target of the p53 tumor suppressor gene." Mol Cancer Res 6.5 (May 2008): 843-850.
PMID
18505928
Source
pubmed
Published In
Molecular cancer research : MCR
Volume
6
Issue
5
Publish Date
2008
Start Page
843
End Page
850
DOI
10.1158/1541-7786.MCR-07-2105

Stat3 constitutive activation is associated with glioma tumor grade: Pathway profiling and therapy

Authors
Lo, H-W; Cao, X; Zhu, H; Ali-Osman, F
MLA Citation
Lo, H-W, Cao, X, Zhu, H, and Ali-Osman, F. "Stat3 constitutive activation is associated with glioma tumor grade: Pathway profiling and therapy." October 2007.
Source
wos-lite
Published In
Neuro-Oncology
Volume
9
Issue
4
Publish Date
2007
Start Page
550
End Page
550

Targeting constitutively activated stat3 sensitizes medulloblastomas to chemotherapeutic agents

Authors
Lo, H-W; Cao, X; Zhu, H; Ali-Osman, F
MLA Citation
Lo, H-W, Cao, X, Zhu, H, and Ali-Osman, F. "Targeting constitutively activated stat3 sensitizes medulloblastomas to chemotherapeutic agents." October 2007.
Source
wos-lite
Published In
Neuro-Oncology
Volume
9
Issue
4
Publish Date
2007
Start Page
560
End Page
560

Targeting hedgehog signaling in medulloblastoma

Authors
Wang, J; Liu, R; Bond, M; Chen, M; Singh, S; Ali-Osman, F; Lefkowitz, RJ; Diehl, AM; Lyerly, HK; Barak, L; Chen, W
MLA Citation
Wang, J, Liu, R, Bond, M, Chen, M, Singh, S, Ali-Osman, F, Lefkowitz, RJ, Diehl, AM, Lyerly, HK, Barak, L, and Chen, W. "Targeting hedgehog signaling in medulloblastoma." October 2007.
Source
wos-lite
Published In
Neuro-Oncology
Volume
9
Issue
4
Publish Date
2007
Start Page
560
End Page
561

Genetic polymorphism and function of glutathione S-transferases in tumor drug resistance.

The human glutathione S-transferase, GSTs, possess both enzymatic and non-enzymatic functions and are involved in many important cellular processes, such as, phase II metabolism, stress response, cell proliferation, apoptosis, oncogenesis, tumor progression and drug resistance. The non-enzymatic functions of GSTs involve their interactions with cellular proteins, such as, JNK, TRAF, ASK, PKC, and TGM2, during which, either the interacting protein partner undergoes functional alteration or the GST protein itself is post-translationally modified and/or functionally altered. The majority of GST genes harbor polymorphisms that influence their transcription and/or function of their encoded proteins. This overview focuses on recent insights into the biology and pharmacogenetics of GSTs as a determinant of cancer drug resistance and response of cancer patients to therapy.

Authors
Lo, H-W; Ali-Osman, F
MLA Citation
Lo, H-W, and Ali-Osman, F. "Genetic polymorphism and function of glutathione S-transferases in tumor drug resistance." Curr Opin Pharmacol 7.4 (August 2007): 367-374. (Review)
PMID
17681492
Source
pubmed
Published In
Current Opinion in Pharmacology
Volume
7
Issue
4
Publish Date
2007
Start Page
367
End Page
374
DOI
10.1016/j.coph.2007.06.009

Defining regional infusion treatment strategies for extremity melanoma: comparative analysis of melphalan and temozolomide as regional chemotherapeutic agents.

Five different human melanoma xenografts were used in a xenograft model of extremity melanoma to evaluate the variability of tumor response to regionally administered melphalan or temozolomide and to determine if various components of pertinent drug resistance pathways for melphalan [glutathione S-transferase (GST)/glutathione] and temozolomide [O(6)-alkylguanine DNA alkyltranferase (AGT)/mismatch repair (MMR)] could be predictive of tumor response. Xenograft-bearing rats underwent regional isolated limb infusion with either melphalan (90 mg/kg) or temozolomide (2,000 mg/kg). The levels of AGT activity, GST activity, glutathione level, and GST/AGT expression were examined in this group of xenografts and found to be quite heterogeneous. No correlation was identified between melphalan sensitivity and the GST/glutathione cellular detoxification pathway. In contrast, a strong correlation between the levels of AGT activity and percentage increase in tumor volume on day 30 (r = 0.88) was noted for tumors treated with temozolomide. Regional therapy with temozolomide was more effective when compared with melphalan for the xenograft with the lowest AGT activity, whereas melphalan was more effective than temozolomide in another xenograft that had the highest AGT activity. In three other xenografts, there was no significant difference in response between the two chemotherapy agents. This study shows that AGT activity may be useful in predicting the utility of temozolomide-based regional therapy for advanced extremity melanoma tumors. Our observations also point out the limited ability of analysis of the GST/glutathione pathway to predict response to chemotherapies like melphalan whose resistance is primarily mediated through a complex mechanism of detoxification.

Authors
Yoshimoto, Y; Augustine, CK; Yoo, JS; Zipfel, PA; Selim, MA; Pruitt, SK; Friedman, HS; Ali-Osman, F; Tyler, DS
MLA Citation
Yoshimoto, Y, Augustine, CK, Yoo, JS, Zipfel, PA, Selim, MA, Pruitt, SK, Friedman, HS, Ali-Osman, F, and Tyler, DS. "Defining regional infusion treatment strategies for extremity melanoma: comparative analysis of melphalan and temozolomide as regional chemotherapeutic agents." Mol Cancer Ther 6.5 (May 2007): 1492-1500.
PMID
17483437
Source
pubmed
Published In
Molecular cancer therapeutics
Volume
6
Issue
5
Publish Date
2007
Start Page
1492
End Page
1500
DOI
10.1158/1535-7163.MCT-06-0718

Redox pathways in cancer drug discovery

Authors
Tew, KD; Ali-Osman, F
MLA Citation
Tew, KD, and Ali-Osman, F. "Redox pathways in cancer drug discovery." Current Opinion in Pharmacology 7.4 (2007): 353-354.
PMID
19823694
Source
scival
Published In
Current Opinion in Pharmacology
Volume
7
Issue
4
Publish Date
2007
Start Page
353
End Page
354
DOI
10.1016/j.coph.2007.07.003

Quantitative analysis of O6-alkylguanine-DNA alkyltransferase in malignant glioma.

Promoter hypermethylation of the DNA repair protein O(6)-alkylguanine-DNA alkyltransferase (AGT) has been associated with an enhanced response to chloroethylating and methylating agents in patients with malignant glioma. The purpose of this study was to compare three distinct yet related indices for measuring AGT to determine if these assays could be used interchangeably when AGT status is to be used to guide chemotherapeutic decisions. Real-time methylation-specific PCR (MSP), assessed as the ratio of methylated AGT copies to internal beta-actin control, was used to quantitate AGT hypermethylation in 32 glioma samples. Data were compared with AGT enzyme activity as well as immunohistochemical detection of AGT protein from the same samples. Hypermethylation of the AGT promoter was detected in 19 of 31 (61%) samples evaluable by MSP. Low-level AGT, defined as <20% nuclear AGT staining by immunohistochemistry, was found in 10 of 32 samples (31%), whereas 12 of 32 (38%) had low levels of AGT activity. Correlation of immunohistochemistry to AGT activity was statistically significant (P = 0.014) as was the correlation of immunohistochemistry to MSP (P = 0.043), whereas MSP compared with AGT activity (P = 0.246) was not significant. Cross-tabulation of immunohistochemistry and MSP data based on prognostic groups, where good prognosis was represented by an immunohistochemistry of <20% and an MSP ratio >12, showed no significant relationship (P = 0.214), suggesting that one assay cannot be used interchangeably for another. The observed discordance between respective measures of AGT based on prognosis supports further standardization of AGT assays designed to guide therapeutic practice. The data also suggest that consideration be given to the large population of AGT-expressing cells within samples when therapeutic strategies based on tumor methylation are used.

Authors
Maxwell, JA; Johnson, SP; Quinn, JA; McLendon, RE; Ali-Osman, F; Friedman, AH; Herndon, JE; Bierau, K; Bigley, J; Bigner, DD; Friedman, HS
MLA Citation
Maxwell, JA, Johnson, SP, Quinn, JA, McLendon, RE, Ali-Osman, F, Friedman, AH, Herndon, JE, Bierau, K, Bigley, J, Bigner, DD, and Friedman, HS. "Quantitative analysis of O6-alkylguanine-DNA alkyltransferase in malignant glioma." Mol Cancer Ther 5.10 (October 2006): 2531-2539.
PMID
17041097
Source
pubmed
Published In
Molecular cancer therapeutics
Volume
5
Issue
10
Publish Date
2006
Start Page
2531
End Page
2539
DOI
10.1158/1535-7163.MCT-06-0106

Polymorphism of the promoter of the epidermal growth factor (EGF) gene in patients, its distribution and correlation with survival in glioma patients

Authors
Ali-Osman, F
MLA Citation
Ali-Osman, F. "Polymorphism of the promoter of the epidermal growth factor (EGF) gene in patients, its distribution and correlation with survival in glioma patients." October 2006.
Source
wos-lite
Published In
Neuro-Oncology
Volume
8
Issue
4
Publish Date
2006
Start Page
420
End Page
420

Glutathione S-transferase P1 (GSTP1) is a novel downstream target of Akt in human gliomas

Authors
Okamura, T; Haystead, T; Bigner, DD; Ali-Osman, F
MLA Citation
Okamura, T, Haystead, T, Bigner, DD, and Ali-Osman, F. "Glutathione S-transferase P1 (GSTP1) is a novel downstream target of Akt in human gliomas." October 2006.
Source
wos-lite
Published In
Neuro-Oncology
Volume
8
Issue
4
Publish Date
2006
Start Page
400
End Page
400

Role of BAY 43-9006 in combination with temozolomide and melphalan in metastatic melanoma

Authors
Yoo, J; Augustine, CK; Yoshimoto, Y; Petersen, RP; Pruitt, SK; Ali-Osman, F; Tyler, DS
MLA Citation
Yoo, J, Augustine, CK, Yoshimoto, Y, Petersen, RP, Pruitt, SK, Ali-Osman, F, and Tyler, DS. "Role of BAY 43-9006 in combination with temozolomide and melphalan in metastatic melanoma." February 2006.
Source
wos-lite
Published In
Annals of Surgical Oncology
Volume
13
Issue
2
Publish Date
2006
Start Page
12
End Page
12

Multimodal dose dense therapy for mantle cell lymphoma.

Authors
Wanko, SO; Gockerman, JP; Moore, JO; de Castro, C; Diehl, L; Pronitz, R; Gasparetto, C; Chute, J; Horwitz, M; Morris, A; Ali-Osman, F; Rao, A; Niedzweicki, D; Long, GD; Chao, NJ; Rizzieri, DA
MLA Citation
Wanko, SO, Gockerman, JP, Moore, JO, de Castro, C, Diehl, L, Pronitz, R, Gasparetto, C, Chute, J, Horwitz, M, Morris, A, Ali-Osman, F, Rao, A, Niedzweicki, D, Long, GD, Chao, NJ, and Rizzieri, DA. "Multimodal dose dense therapy for mantle cell lymphoma." November 16, 2005.
Source
wos-lite
Published In
Blood
Volume
106
Issue
11
Publish Date
2005
Start Page
463B
End Page
463B

Poly(ADP-ribose) polymerase-1 inhibition reverses temozolomide resistance in a DNA mismatch repair-deficient malignant glioma xenograft.

Temozolomide is a DNA-methylating agent used in the treatment of malignant gliomas. In this study, we have examined if inhibition of poly(ADP-ribose) polymerase (PARP) could increase the cytotoxicity of temozolomide, particularly in cells deficient in DNA mismatch repair. Athymic mice, transplanted with mismatch repair-proficient [D-245 MG] or deficient [D-245 MG (PR)] xenografts, were treated with a combination of temozolomide and the PARP inhibitor, INO-1001. For the tumors deficient in mismatch repair, the most effective dose of INO-1001 was found to be 150 mg/kg, given i.p. thrice at 4-hour intervals with the first injection in combination with 262.5 mg/kg temozolomide (0.75 LD(10)). This dose of temozolomide by itself induced no partial regressions and a 4-day growth delay. In two separate experiments, the combination therapy increased the growth delay by 21.6 and 9.7 days with partial regressions observed in four of eight and three of nine mice, respectively. The addition of INO-1001 had a more modest, yet statistically significant, increase in tumor growth delay in the mismatch repair-proficient xenografts. In these experiments, mice were treated with a lower amount of temozolomide (88 mg/kg), which resulted in growth delays of 43.1 and 39.2 days. When the temozolomide treatment was in combination with 200 mg/kg INO-1001, there was an increase in growth delay to 48.9 and 45.7 days, respectively. These results suggest that inhibition of PARP may increase the efficacy of temozolomide in the treatment of malignant gliomas, particularly in tumors deficient in DNA mismatch repair.

Authors
Cheng, CL; Johnson, SP; Keir, ST; Quinn, JA; Ali-Osman, F; Szabo, C; Li, H; Salzman, AL; Dolan, ME; Modrich, P; Bigner, DD; Friedman, HS
MLA Citation
Cheng, CL, Johnson, SP, Keir, ST, Quinn, JA, Ali-Osman, F, Szabo, C, Li, H, Salzman, AL, Dolan, ME, Modrich, P, Bigner, DD, and Friedman, HS. "Poly(ADP-ribose) polymerase-1 inhibition reverses temozolomide resistance in a DNA mismatch repair-deficient malignant glioma xenograft." Mol Cancer Ther 4.9 (September 2005): 1364-1368.
PMID
16170028
Source
pubmed
Published In
Molecular cancer therapeutics
Volume
4
Issue
9
Publish Date
2005
Start Page
1364
End Page
1368
DOI
10.1158/1535-7163.MCT-05-0128

Glutathione S-transferase as a marker of metastatic potential in malignant melanoma

Authors
Yoo, JS; Yoshimoto, Y; Petersen, RP; Pruitt, SK; Ali-Osman, F; Tyler, DS
MLA Citation
Yoo, JS, Yoshimoto, Y, Petersen, RP, Pruitt, SK, Ali-Osman, F, and Tyler, DS. "Glutathione S-transferase as a marker of metastatic potential in malignant melanoma." September 2005.
Source
wos-lite
Published In
Journal of The American College of Surgeons
Volume
201
Issue
3
Publish Date
2005
Start Page
S84
End Page
S84
DOI
10.1016/j.jamcollsurg.2005.06.197

A novel mechanism of PKA- and PKC-dependent drug resistance in human gliomas involving phosphorylation and metabolic activation of glutathione S-transferase P1 (GSTP1)

Authors
Ali-Osman, F; Lo, H; Antoun, G; Friedman, A; Friedman, H; Bigner, D
MLA Citation
Ali-Osman, F, Lo, H, Antoun, G, Friedman, A, Friedman, H, and Bigner, D. "A novel mechanism of PKA- and PKC-dependent drug resistance in human gliomas involving phosphorylation and metabolic activation of glutathione S-transferase P1 (GSTP1)." July 2005.
Source
wos-lite
Published In
Neuro-Oncology
Volume
7
Issue
3
Publish Date
2005
Start Page
377
End Page
377

Prevalence and prognostic significance of polymorphisms at the glutathione S-transferase M1, M3, P1, and T1 gene loci in human astrocytomas

Authors
Ali-Osman, F; Herndon, JE; Stephenson, L; Davis, F; McCarthy, B; Reardon, D; Friedman, A; McClendon, R; Friedman, H; Bigner, DD
MLA Citation
Ali-Osman, F, Herndon, JE, Stephenson, L, Davis, F, McCarthy, B, Reardon, D, Friedman, A, McClendon, R, Friedman, H, and Bigner, DD. "Prevalence and prognostic significance of polymorphisms at the glutathione S-transferase M1, M3, P1, and T1 gene loci in human astrocytomas." July 2005.
Source
wos-lite
Published In
Neuro-Oncology
Volume
7
Issue
3
Publish Date
2005
Start Page
304
End Page
304

Article on the enforced expression of wild-type p53 and the transcription of the O-6 -methylguanine-DNA methyltransferase gene (vol 7, pg 1398, 2001)

Authors
Shou, J; Srivenugopal, KS; Mullapudi, SRS; Lang, FF; Rao, JS; Ali-Osman, F
MLA Citation
Shou, J, Srivenugopal, KS, Mullapudi, SRS, Lang, FF, Rao, JS, and Ali-Osman, F. "Article on the enforced expression of wild-type p53 and the transcription of the O-6 -methylguanine-DNA methyltransferase gene (vol 7, pg 1398, 2001)." CLINICAL CANCER RESEARCH 11.6 (March 15, 2005): 2449-2449.
Source
wos-lite
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
11
Issue
6
Publish Date
2005
Start Page
2449
End Page
2449

Erratum: Enforced expression of wild-type p53 curtails the transcription of the O6-methylguanine-DNA methyltransferase gene in human tumor cells and enhances their sensitivity to alkylating agents (Clinical Cancer Research (May 1, 2001) 7 (1398-1409))

Authors
Shou, J; Srivenugopal, KS; Mullapudi, SRS; Jr, FFL; Rao, JS; Ali-Osman, F
MLA Citation
Shou, J, Srivenugopal, KS, Mullapudi, SRS, Jr, FFL, Rao, JS, and Ali-Osman, F. "Erratum: Enforced expression of wild-type p53 curtails the transcription of the O6-methylguanine-DNA methyltransferase gene in human tumor cells and enhances their sensitivity to alkylating agents (Clinical Cancer Research (May 1, 2001) 7 (1398-1409))." Clinical Cancer Research 11.6 (2005): 2449--.
Source
scival
Published In
Clinical Cancer Research
Volume
11
Issue
6
Publish Date
2005
Start Page
2449-
DOI
10.1158/1078-0432.CCR-11-6-COR

The human glutathione S-transferase P1 protein is phosphorylated and its metabolic function enhanced by the Ser/Thr protein kinases, cAMP-dependent protein kinase and protein kinase C, in glioblastoma cells.

We report here that the human glutathione S-transferase P1 (GSTP1) protein, involved in phase II metabolism of many carcinogens and anticancer agents and in the regulation of c-Jun NH(2)-terminal kinase-mediated cell signaling, undergoes phosphorylation by the Ser/Thr protein kinases, cAMP-dependent protein kinase (PKA) and protein kinase C (PKC), resulting in a significant enhancement of its metabolic activity. GSTP1 phosphorylation by PKA was glutathione (GSH)-dependent, whereas phosphorylation by PKC did not require but was significantly enhanced by GSH. In the presence of GSH, the stoichiometry of phosphorylation was 0.4 +/- 0.03 and 0.53 +/- 0.02 mol incorporated phosphate per mole of dimeric GSTP1 protein. The GSTP1 protein was phosphorylated, in the presence of GSH, by eight different PKC isoforms (alpha, betaIota, betaIotaIota, delta, epsilon, gamma, eta, and zeta), belonging to the three major PKC subclasses, albeit with various efficiencies. The catalytic efficiency, k(cat)/K(m), of the phosphorylated GSTP1 was more than double that of the unphosphorylated protein. In MGR3 human glioblastoma cells, PKA and PKC activation resulted in a significant increase in the level of phosphorylation of the GSTP1 protein and was accompanied by a 2.1- and 2.7-fold increase, respectively, in specific GSTP1 activity in the cells. Peptide phosphorylation analyses and both phosphorylation and enzyme kinetic studies with GSTP1 proteins mutated at candidate amino acid residues established Ser-42 and Ser-184 as putative phospho-acceptor residues for both kinases in the GSTP1 protein. Together, these findings show PKA- and PKC-dependent phosphorylation as a significant post-translational mechanism of regulation of GSTP1 function. The GSH-dependence of the phosphorylation suggests that under high intracellular GSH conditions, such as is present in most drug-resistant tumors, the GSTP1 protein will exist in a hyper-phosphorylated and enzymatically more active state. In normal cells, the functional activation of the GSTP1 protein by PKA- and PKC-dependent phosphorylation could represent a potentially important mechanism of cellular protection, whereas in tumors, increased phase II metabolism of anticancer drugs by the more active phosphorylated GSTP1 protein could contribute to the drug resistance and therapeutic failure frequently associated with increased activities of these Ser/Thr kinases.

Authors
Lo, H-W; Antoun, GR; Ali-Osman, F
MLA Citation
Lo, H-W, Antoun, GR, and Ali-Osman, F. "The human glutathione S-transferase P1 protein is phosphorylated and its metabolic function enhanced by the Ser/Thr protein kinases, cAMP-dependent protein kinase and protein kinase C, in glioblastoma cells." Cancer Res 64.24 (December 15, 2004): 9131-9138.
PMID
15604283
Source
pubmed
Published In
Cancer Research
Volume
64
Issue
24
Publish Date
2004
Start Page
9131
End Page
9138
DOI
10.1158/0008-5472.CAN-04-0283

Stat3 activation regulates the expression of matrix metalloproteinase-2 and tumor invasion and metastasis.

The expression of matrix metalloproteinase-2 (MMP-2) has been linked with tumor invasion, angiogenesis, and metastasis. However, the molecular basis for MMP-2 overexpression in tumor cells remains unclear. In this study, by using K-1735 melanoma system, we demonstrated that highly metastatic C4, M2, and X21 tumor cells express elevated MMP-2 mRNA and enzymatic activity, whereas poorly metastatic C10, C19, and C23 tumor cells express much lower levels. Moreover, a concomitant elevated Stat3 activity has been detected in these metastatic tumor cells that overexpress MMP-2. Transfection of constitutively activated Stat3 into poorly metastatic C23 tumor cells directly activated the MMP-2 promoter, whereas the expression of a dominant-negative Stat3 in highly metastatic C4 tumor cells inhibited the MMP-2 promoter. A high-affinity Stat3-binding element was identified in the MMP-2 promoter and Stat3 protein bound directly to the MMP-2 promoter. Blockade of activated Stat3 through expression of a dominant-negative Stat3 significantly suppressed MMP-2 expression in the metastatic tumor cells. Therefore, overexpression of MMP-2 in the metastatic melanoma cells can be attributed to elevated Stat3 activity, and Stat3 upregulates the transcription of MMP-2 through direct interaction with the MMP-2 promoter. Furthermore, blockade of activated Stat3 in highly metastatic C4 cells significantly suppressed the invasiveness of the tumor cells, inhibited tumor growth, and prevented metastasis in nude mice. Collectively, these studies suggest that Stat3 signaling directly regulates MMP-2 expression, tumor invasion, and metastasis, and that Stat3 activation might be a crucial event in the development of metastasis.

Authors
Xie, T-X; Wei, D; Liu, M; Gao, AC; Ali-Osman, F; Sawaya, R; Huang, S
MLA Citation
Xie, T-X, Wei, D, Liu, M, Gao, AC, Ali-Osman, F, Sawaya, R, and Huang, S. "Stat3 activation regulates the expression of matrix metalloproteinase-2 and tumor invasion and metastasis." Oncogene 23.20 (April 29, 2004): 3550-3560.
PMID
15116091
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
23
Issue
20
Publish Date
2004
Start Page
3550
End Page
3560
DOI
10.1038/sj.onc.1207383

Glutathione S-transferase polymorphisms and survival in primary malignant glioma.

PURPOSE: The purpose of this research was to investigate the relationship between glutathione S-transferase (GST) polymorphisms and survival, and chemotherapy-related toxicity in 278 glioma patients. EXPERIMENTAL DESIGN: We determined genetic variants for GSTM1, GSTT1, and GSTP1 enzymes by PCR and restriction fragment length polymorphisms. We conducted Kaplan-Meier and Cox-proportional hazard analyses to examine whether the GST polymorphisms are related to overall survival, and logistic regression analysis to explore whether the GST polymorphisms are associated with toxicity. RESULTS: For patients with anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic oligoastrocytoma, and anaplastic ependymoma (n = 78), patients with GSTP1*A/*A-M1 null genotype survived longer than did the rest of the group (median survival "not achieved," and 41 months, respectively; P = 0.06). Among patients treated with nitrosoureas (n = 108), those with GSTP1*A/*A and GSTM1 null genotype were 5.7 times (95% confidence interval, 0.9-37.4) more likely to experience an adverse event secondary to chemotherapy, compared with the others. CONCLUSIONS: In patients with anaplastic astrocytoma, anaplastic oligodendroglioma, and anaplastic oligoastrocytoma, combination of germ-line GSTP1*A/*A and GSTM1 null genotype confers a survival advantage. Patients with this genotype also have an increased risk of adverse events secondary to chemotherapy that primarily comprised nitrosourea alkylating agents.

Authors
Okcu, MF; Selvan, M; Wang, L-E; Stout, L; Erana, R; Airewele, G; Adatto, P; Hess, K; Ali-Osman, F; Groves, M; Yung, AWK; Levin, VA; Wei, Q; Bondy, M
MLA Citation
Okcu, MF, Selvan, M, Wang, L-E, Stout, L, Erana, R, Airewele, G, Adatto, P, Hess, K, Ali-Osman, F, Groves, M, Yung, AWK, Levin, VA, Wei, Q, and Bondy, M. "Glutathione S-transferase polymorphisms and survival in primary malignant glioma." Clinical cancer research : an official journal of the American Association for Cancer Research 10.8 (April 2004): 2618-2625.
PMID
15102663
Source
epmc
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
10
Issue
8
Publish Date
2004
Start Page
2618
End Page
2625
DOI
10.1158/1078-0432.ccr-03-0053

High-throughput detection of glutathione s-transferase polymorphic alleles in a pediatric cancer population.

Polymorphisms of glutathione S-transferase (GST) enzymes have been correlated with altered risk of several cancers, as well as altered response and toxicity from cancer chemotherapy. We report a low cost, highly reproducible and specific PCR-based high-throughput assay for genotyping different GSTs designed for use in large clinical trials. In comparison to an alternative genotyping method (single nucleotide extension), the sensitivity and specificity of the high throughput assay was shown to be 92 and 97%, respectively, depending on the source of genomic DNA. Using the high-throughput assay, we demonstrate by multivariate analysis an increased risk of acute lymphoblastic leukemia, glial brain tumors, and osteosarcoma for patients carrying nonnull alleles of GSTM1 and/or GSTT1.

Authors
Barnette, P; Scholl, R; Blandford, M; Ballard, L; Tsodikov, A; Magee, J; Williams, S; Robertson, M; Ali-Osman, F; Lemons, R; Keller, C
MLA Citation
Barnette, P, Scholl, R, Blandford, M, Ballard, L, Tsodikov, A, Magee, J, Williams, S, Robertson, M, Ali-Osman, F, Lemons, R, and Keller, C. "High-throughput detection of glutathione s-transferase polymorphic alleles in a pediatric cancer population." Cancer Epidemiol Biomarkers Prev 13.2 (February 2004): 304-313.
PMID
14973099
Source
pubmed
Published In
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology
Volume
13
Issue
2
Publish Date
2004
Start Page
304
End Page
313

Promoter methylation and silencing of the tissue factor pathway inhibitor-2 (TFPI-2), a gene encoding an inhibitor of matrix metalloproteinases in human glioma cells.

We have shown previously that the tissue factor pathway inhibitor-2 (TFPI-2), a broad range proteinase inhibitor, is highly expressed in low-grade gliomas, but, minimally expressed or undetectable in glioblastomas, and that enforced expression of this gene reduces the invasive properties of brain tumor cells. Here, we examined the role of promoter methylation as a mechanism of TFPI-2 gene silencing. In SNB19 glioblastoma cells, which have no detectable TFPI-2 expression, 5-aza-2'-deoxycytidine (5aC), an inhibitor of DNA methyltransferase, induced TFPI-2 mRNA in a dose-dependent manner. Trichostatin A (TSA), the histone deacetylase (HDAC) inhibitor, by itself, was more efficient than 5aC in inducing TFPI-2 transcripts, and the 5aC+TSA combination resulted in highly synergistic reactivation of the gene, both at the transcript and protein levels. In Hs683 glioma cells, which express the TFPI-2 gene at high levels, transfection of the in vitro methylated TFPI-2 promoter constructs resulted in a drastic decrease of promoter activity compared to the unmethylated promoter. Further, the methylation-specific PCR in SNB19 and Hs683 cells showed that TFPI-2 gene repression was closely linked with methylation of the CpG islands in the promoter. Finally, the chromatin immunoprecipitation assays in SNB19 cells showed that the methylated and repressed TFPI-2 promoter was associated with the methyl-CpG binding protein 2 (MeCP2), and that gene reactivation resulted in the loss of MeCP2 from this site. These studies establish that TFPI-2 is transcriptionally silenced through promoter methylation in SNB19 cells.

Authors
Konduri, SD; Srivenugopal, KS; Yanamandra, N; Dinh, DH; Olivero, WC; Gujrati, M; Foster, DC; Kisiel, W; Ali-Osman, F; Kondraganti, S; Lakka, SS; Rao, JS
MLA Citation
Konduri, SD, Srivenugopal, KS, Yanamandra, N, Dinh, DH, Olivero, WC, Gujrati, M, Foster, DC, Kisiel, W, Ali-Osman, F, Kondraganti, S, Lakka, SS, and Rao, JS. "Promoter methylation and silencing of the tissue factor pathway inhibitor-2 (TFPI-2), a gene encoding an inhibitor of matrix metalloproteinases in human glioma cells." Oncogene 22.29 (July 17, 2003): 4509-4516.
PMID
12881707
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
22
Issue
29
Publish Date
2003
Start Page
4509
End Page
4516
DOI
10.1038/sj.onc.1206695

Association between glutathione S-transferase p1 polymorphisms and lung cancer risk in Caucasians: a case-control study.

Glutathione transferases (GSTs), a multiple gene family of phase II enzymes, catalyze detoxifying endogenous reactions with glutathione and protect cellular macromolecules from damage caused by cytotoxic and carcinogenic agents. Glutathione S-transferase p1 (GSTP1), the most abundant GST isoform in the lung, metabolizes numerous carcinogenic compounds including benzo[a]pyrene, a tobacco carcinogen. Previous studies suggest that genetic polymorphisms of GSTP1 exon 5 (Ile105Val) and exon 6 (Ala114Val) have functional effects on the GST gene product resulting in reduced enzyme activity. Individuals with reduced GST enzymatic activity may be at a greater risk for cancer due to decreased detoxification of carcinogenic and mutagenic compounds. Utilizing a hospital-based case-control study, we investigated the association between GSTP1 polymorphisms at exons 5 and 6 with lung cancer risk. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was used to successfully genotype the GSTP1 exons 5 and 6 polymorphism in 582 Caucasian lung cancer cases and 600 frequency matched Caucasian controls. There was no association between the exon 5 variant genotypes (A/G+G/G) and overall lung cancer risk (OR=1.09; 95% CI 0.82-1.45) nor when stratified by age, gender, and smoking status. However, the exon 6 variant genotypes (C/T+T/T) were associated with a statistically significant elevated lung cancer risk (OR=1.40; 95% CI 1.06-1.92). Additionally, there was an increase in lung cancer risk for the exon 6 variant genotypes in younger individuals (<62 years) (OR=1.63; 95% C.I. 1.07-2.49) but no effect in older individuals (OR=1.14; 95% CI 0.72-1.81). A statistically significant increased risk of lung cancer was also observed for the exon 6 variant genotypes among men (OR=2.17; 95% CI 1.41-3.33), but not among women (OR=0.80; 95% CI 0.51-1.28). Among ever smokers, the exon 6 variant genotypes were associated with an elevated lung cancer risk (OR=1.58; 95% CI 1.14-2.19), which was not evident for never smokers (OR=0.53; 95% CI 0.21-1.33). These data demonstrate that the GSTP1 exon 6 polymorphism, but not the exon 5 polymorphism, is associated with lung cancer risk that is especially evident in men, younger individuals, and ever smokers.

Authors
Wang, Y; Spitz, MR; Schabath, MB; Ali-Osman, F; Mata, H; Wu, X
MLA Citation
Wang, Y, Spitz, MR, Schabath, MB, Ali-Osman, F, Mata, H, and Wu, X. "Association between glutathione S-transferase p1 polymorphisms and lung cancer risk in Caucasians: a case-control study." Lung Cancer 40.1 (April 2003): 25-32.
PMID
12660004
Source
pubmed
Published In
Lung Cancer
Volume
40
Issue
1
Publish Date
2003
Start Page
25
End Page
32

Glutathione S-transferase M1 and T1 genetic polymorphisms, alcohol consumption and breast cancer risk.

Alcohol consumption has been inconsistently associated with breast cancer risk. Recent studies suggest that genetic polymorphisms of glutathione S-transferases (GSTs) may modify this relation. To determine if breast cancer risk is associated with GSTM1 and GSTT1 genetic polymorphisms, and to evaluate the effect modification between GST genotypes and alcohol consumption in the risk of breast cancer, we conducted a case-control study in the state of Connecticut in the period 1998 and 2001. Cases were histologically confirmed, incident breast cancer patients in New Haven County, CT. Controls were randomly selected from women histologically confirmed to be without breast cancer. The study results show that, while GSTM1 genotypes were not associated with breast cancer risk, GSTT1-null genotype was associated with a significant 90% increased risk for postmenopausal women (OR=1.9, 95% CI 1.2-3.0). Analysis by GST genotypes and alcohol consumption shows that GSTM1A ever-drinking women had a 2.5-fold (OR=2.5, 95% CI 1.1-5.5) increased risk of breast cancer compared to the GSTM1A never-drinkers, and the risk increases with duration and daily amount of alcohol consumption. Postmenopausal women with GSTT1-null genotype, who consumed a lifetime of >250 kg of spirit-equivalents, had an almost seven-fold increased risk (OR=6.8, 95% CI 1.4-33.9), and drinking commencing at younger ages appears to carry a higher risk. An OR of 8.2 (95% CI 1.2-57.4) was observed for those with GSTM1A, and GSTT1-null genotypes who had consumed a lifetime of >250 kg of spirit-equivalents. In conclusion, alcohol consumption may increase breast cancer risk among those who carry susceptible GST genotypes.

Authors
Zheng, T; Holford, TR; Zahm, SH; Owens, PH; Boyle, P; Zhang, Y; Zhang, B; Wise, JP; Stephenson, LP; Ali-Osman, F
MLA Citation
Zheng, T, Holford, TR, Zahm, SH, Owens, PH, Boyle, P, Zhang, Y, Zhang, B, Wise, JP, Stephenson, LP, and Ali-Osman, F. "Glutathione S-transferase M1 and T1 genetic polymorphisms, alcohol consumption and breast cancer risk." Br J Cancer 88.1 (January 13, 2003): 58-62.
PMID
12556960
Source
pubmed
Published In
British Journal of Cancer
Volume
88
Issue
1
Publish Date
2003
Start Page
58
End Page
62
DOI
10.1038/sj.bjc.6600708

Promoter methylation and silencing of the tissue factor pathway inhibitor-2 (TFPI-2), in human glioma cells

We have shown previously that the tissue factor pathway inhibitor-2 (TFPI-2), a broad range proteinase inhibitor, is highly expressed in low-grade gliomas, but, minimally expressed or undetectable in glioblastomas, and that enforced expression of this gene reduces the invasive properties of brain tumor cells. Here, we examined the role of promoter methylation as a mechanism of TFPI-2 gene silencing. In SNB19 glioblastoma cells, which have no detectable TFPI-2 expression, 5-aza-2′-deoxycytidine (5aC), an inhibitor of DNA methyltransferase, induced TFPI-2 mRNA in a dose-dependent manner. Trichostatin A (TSA), the histone deacetylase (HDAC) inhibitor, by itself, was more efficient than 5aC in inducing TFPI-2 transcripts, and the 5aC + TSA combination resulted in highly synergistic reactivation of the gene, both at the transcript and protein levels. In Hs683 glioma cells, which express the TFPI-2 gene at high levels, transfection of the in vitro methylated TFPI-2 promoter constructs resulted in a drastic decrease of promoter activity compared to the unmethylated promoter. Further, the methylation-specific PCR in SNB19 and Hs683 cells showed that TFPI-2 gene repression was closely linked with methylation of the CpG islands in the promoter. Finally, the chromatin immunoprecipitation assays in SNB19 cells showed that the methylated and repressed TFPI-2 promoter was associated with the methyl-CpG binding protein 2 (MeCP2), and that gene reactivation resulted in the loss of MeCP2 from this site. These studies establish that TFPI-2 is transcriptionally silenced through promoter methylation in SNB19 cells.

Authors
Konduri, SD; Srivenugopal, KS; Yanamandra, N; Dinh, DH; Olivero, WC; Gujrati, M; Foster, DC; Kisiel, W; Ali-Osman, F; Kondraganti, S; Lakka, SS; Rao, JS
MLA Citation
Konduri, SD, Srivenugopal, KS, Yanamandra, N, Dinh, DH, Olivero, WC, Gujrati, M, Foster, DC, Kisiel, W, Ali-Osman, F, Kondraganti, S, Lakka, SS, and Rao, JS. "Promoter methylation and silencing of the tissue factor pathway inhibitor-2 (TFPI-2), in human glioma cells." Oncogene 22.29 (2003): 4509-4516.
Source
scival
Published In
Oncogene
Volume
22
Issue
29
Publish Date
2003
Start Page
4509
End Page
4516
DOI
10.1038/sj.onc.1206695

Pharmacogenetics of the human glutathione S-transferase P1 gene and tumor response to chemotherapy

Authors
Ishimoto, T; Ali-Osman, F
MLA Citation
Ishimoto, T, and Ali-Osman, F. "Pharmacogenetics of the human glutathione S-transferase P1 gene and tumor response to chemotherapy." November 2002.
Source
wos-lite
Published In
European Journal of Cancer
Volume
38
Publish Date
2002
Start Page
S157
End Page
S158

Allelic variants of the human glutathione S-transferase P1 gene confer differential cytoprotection against anticancer agents in Escherichia coli.

The polymorphic human GSTP1 gene locus encodes proteins that differentially metabolize electrophilic substrates, including, many chemotherapeutic agents used in clinical cancer therapy. In this study, we used XL1-Blue MRF strain, transformed with phagemid expression vectors carrying cDNAs of three GSTP1 alleles, to investigate the cytoprotective abilities of the different GSTP1 alleles against four clinically active anticancer agents, namely, carboplatin, cisplatin, thiotepa, and 4-hydroperoxyifosfamide. Following induction of protein expression with isopropyl-beta-d-thiogalactoside, the cells were treated with each drug for 3 h (1 h for 4-hydroperoxyifosfamide). Surviving fractions were determined and used to compute a cytoprotective factor for each allele against each drug. The results showed all the GSTP1 alleles to be cytoprotective, albeit, to different degrees. For cisplatin and carboplatin, the allele was most protective, with CPs of 5.58 and 3.76, respectively, compared with 1.21 and 1.61 for and 2.50 and 2.79 for. In contrast, protection against thiotepa was highest for the allele, with a cytoprotective factor of 1.56, compared to 1.32 for and 1.1 for. For 4-hydroperoxyifosfamide, the CP for and was the same, 1.45, compared with 1.18 for. These data demonstrate significant differences in the ability of the different GSTP1 alleles to protect against the cytotoxicity of electrophilic anticancer agents. The level of protection differs significantly between different GSTP1 alleles, and between different anticancer agents. The optimized prokaryotic system described provides a useful and rapid tool for pharmacogenetic analysis of the effects of genes on drug sensitivity.

Authors
Ishimoto, TM; Ali-Osman, F
MLA Citation
Ishimoto, TM, and Ali-Osman, F. "Allelic variants of the human glutathione S-transferase P1 gene confer differential cytoprotection against anticancer agents in Escherichia coli." Pharmacogenetics 12.7 (October 2002): 543-553.
PMID
12360105
Source
pubmed
Published In
Pharmacogenetics and Genomics
Volume
12
Issue
7
Publish Date
2002
Start Page
543
End Page
553

A high throughput fluorescent assay for the detection of glutathione S-transferase polymorphic alleles

Authors
Scholl, R; Blandford, M; Ballard, L; Magee, JB; Williams, S; Robertson, M; Ali-Osman, F; Lemons, R; Keller, C
MLA Citation
Scholl, R, Blandford, M, Ballard, L, Magee, JB, Williams, S, Robertson, M, Ali-Osman, F, Lemons, R, and Keller, C. "A high throughput fluorescent assay for the detection of glutathione S-transferase polymorphic alleles." October 2002.
Source
wos-lite
Published In
The American Journal of Human Genetics
Volume
71
Issue
4
Publish Date
2002
Start Page
463
End Page
463

Cigarette smoking, glutathione-s-transferase M1 and t1 genetic polymorphisms, and breast cancer risk (United States).

OBJECTIVE: It has been suggested that functional polymorphisms in genes encoding tobacco carcinogen-metabolizing enzymes may modify the relationship between tobacco smoking and breast cancer risk. We sought to determine if there is a gene-environment interaction between GSTM I (GSTM1A and GSTM1B), and GSTT1 genotypes and cigarette smoking in the risk of breast cancer. METHODS: Cases and controls were recruited in a case-control study conducted in Connecticut from 1994 to 1998. Cases were histologically confirmed, incident breast cancer patients, and controls were randomly selected from women histologically confirmed to be without breast cancer. A total of 338 cases and 345 controls were genotyped for GSTM1 and GSTT1 . RESULTS: None of the GSTM 1 genotypes, either alone or in combination with cigarette smoking, was associated with breast cancer risk. There was, however, a significantly increased risk of breast cancer among postmenopausal women with a GSTTI null genotype (OR= 1.9, 95% CI 1.2-2.9). There were also indications of increased risk of breast cancer associated with cigarette smoking for postmenopausal women with GSTT1-null genotype, especially for those who commenced smoking before age 18 (OR = 2.9, 95% CI 1.0-8.8). CONCLUSION: Women with a GSTT1-null genotype may have an increased breast cancer risk, especially postmenopausal women who started smoking at younger ages.

Authors
Zheng, T; Holford, TR; Zahm, SH; Owens, PH; Boyle, P; Zhang, Y; Wise, JP; Stephenson, LP; Ali-Osman, F
MLA Citation
Zheng, T, Holford, TR, Zahm, SH, Owens, PH, Boyle, P, Zhang, Y, Wise, JP, Stephenson, LP, and Ali-Osman, F. "Cigarette smoking, glutathione-s-transferase M1 and t1 genetic polymorphisms, and breast cancer risk (United States)." Cancer Causes Control 13.7 (September 2002): 637-645.
PMID
12296511
Source
pubmed
Published In
Cancer Causes & Control
Volume
13
Issue
7
Publish Date
2002
Start Page
637
End Page
645

The DNA repair protein, O(6)-methylguanine-DNA methyltransferase is a proteolytic target for the E6 human papillomavirus oncoprotein.

We have previously shown that O(6)-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein that protects tissues against toxic and carcinogenic effects of alkylating agents, is degraded through ubiquitination-dependent proteolysis. Here, we investigated the role of the human papillomavirus (HPV) E6 protein in MGMT degradation. In three pairs of isogenic human tumor cell lines in which a member of each pair expressed the E6 protein through stable transfection (HCT116/HCT116-E6, MCF7/MCF7-E6, and RKO/RKO-E6), we found a consistent 40-55% reduction in the MGMT protein level and its activity in all E6-expressing cells compared with the parent cells (P=<0.05). E6 expression did not, however, alter the levels of MGMT mRNA. Addition of the recombinant MGMT (rMGMT) protein to extracts of HCT116/E6 cells resulted in the binding of E6 to MGMT. Further, the purified E6 protein promoted the degradation of rMGMT in rabbit reticulocyte lysates. Immunoprecipitation assays showed the presence of a ternary protein complex between MGMT, E6, and the cellular ubiquitin-ligase E6-associated protein (E6-AP). Transient transfection of the p53-null H1299 lung tumor cells with an E6 construct also down-regulated the MGMT. The MGMT protein also showed structural features that are compatible for interaction with the E6, and E6-AP components. Collectively, these data suggest that the oncogenic E6 proteins enhance the ubiquitin-dependent proteolysis of MGMT.

Authors
Srivenugopal, KS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, and Ali-Osman, F. "The DNA repair protein, O(6)-methylguanine-DNA methyltransferase is a proteolytic target for the E6 human papillomavirus oncoprotein." Oncogene 21.38 (August 29, 2002): 5940-5945.
PMID
12185595
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
21
Issue
38
Publish Date
2002
Start Page
5940
End Page
5945
DOI
10.1038/sj.onc.1205762

Phosphorylation of O6-alkylguanine-DNA alkyltransferase: experience with a GST-fusion protein and a new pull-down assay.

We showed recently that human O6-alkylguanine-DNA alkyltransferase (AGT), a key target for enhancing the efficacy of anticancer alkylating agents, is regulated by phosphorylation in brain tumor cells. This report describes the problems we encountered in using a glutathione S-transferase (GST)-tagged AGT as the substrate in our search for cellular AGT kinases, validation of a new pull-down assay for AGT phosphorylation, and its wide applicability for quantitating protein kinases in crude extracts and purified fractions. The GST-tag present in the fusion protein, by itself, was found to undergo significant phosphorylation by tumor cell extracts and contribute to spurious results. Instead, we used a histidine-tagged AGT protein, and its micro-scale purification with Talon resin as the basis for a quantitative pull-down assay, and applied it for measuring AGT phosphorylation by protein kinase C (PKC) and other cellular kinases. The pull-down procedure can be easily adopted for quantitating protein kinases in a variety of settings, as it overcomes the need for substrate immunoprecipitation when whole cell extracts are used, and eliminates the autophosphorylated kinase proteins, when purified kinases are used. Our observations call for caution in interpreting the results with GST-fusion proteins in phosphorylation studies.

Authors
Srivenugopal, KS; Mullapudi, SRS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, Mullapudi, SRS, and Ali-Osman, F. "Phosphorylation of O6-alkylguanine-DNA alkyltransferase: experience with a GST-fusion protein and a new pull-down assay." Cancer Lett 181.1 (July 8, 2002): 87-93.
PMID
12430183
Source
pubmed
Published In
Cancer Letters
Volume
181
Issue
1
Publish Date
2002
Start Page
87
End Page
93

Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma.

Medulloblastoma (D-341 MED) and rhabdomyosarcoma (TE-671) cell lines, which are resistant to either 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) or the combination of BCNU and O6-benzylguanine (O6-BG), were generated by serial escalation of BCNU. The activities of O6-alkylguanine-DNA alkyltransferase (AGT), glutathione-S-transferase (GST), and total glutathione (GSH) of the parental, BCNU-resistant (BR), and BCNU + O6-BG-resistant (OBR) cells were measured. No significant differences in GST activity or total GSH were seen between the parental, BR, and OBR cells of both TE-671 and D-341 MED. The AGT activities of D-341 MED (BR) and TE-671 (BR) were twice those of D-341 MED and TE-671, respectively, confirming the importance of this enzyme for BCNU resistance. The D-341 MED (OBR) cells did not exhibit any AGT activity, suggesting that another mechanism must play a role in the drug resistance. Fewer DNA interstrand cross-links (ICLs) were observed in D-341 MED (OBR) than in D-341 MED after 8 h BCNU (100-400 microM) treatment. However, the amounts of DNA ICLs observed in D-341 MED and D-341 MED (OBR) were stable after 24 h. Microarray analysis showed the increased expressions of several metallothionein genes and down-regulation of several proapoptotic genes. The AGT activity of TE-671 (OBR) was 223 fmol/mg when the cells were grown in 10 microM O6-BG and decreased to about half this value when the O6-BG concentration was increased 60 microM. The AGT cDNA of TE-671 (OBR) cells was cloned and found to contain a G-to-T transversion at codon 156, resulting in conversion of glycine to cysteine (G156C). In vitro mutagenesis has shown that the G156C AGT mutant is resistant to inactivation by O6-BG. Thus, the selection of a mutant AGT with decreased sensitivity to O6-BG is a significant contributing factor to BCNU + O6-BG resistance.

Authors
Bacolod, MD; Johnson, SP; Ali-Osman, F; Modrich, P; Bullock, NS; Colvin, OM; Bigner, DD; Friedman, HS
MLA Citation
Bacolod, MD, Johnson, SP, Ali-Osman, F, Modrich, P, Bullock, NS, Colvin, OM, Bigner, DD, and Friedman, HS. "Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma." Mol Cancer Ther 1.9 (July 2002): 727-736.
PMID
12479369
Source
pubmed
Published In
Molecular cancer therapeutics
Volume
1
Issue
9
Publish Date
2002
Start Page
727
End Page
736

Analysis and significance of the genetic polymorphism of the glutathione S-transferase P1 gene locus in pediatric tumors

Authors
Madden, RM; Chan, KW; Stephenson, LP; Ali-Osman, F
MLA Citation
Madden, RM, Chan, KW, Stephenson, LP, and Ali-Osman, F. "Analysis and significance of the genetic polymorphism of the glutathione S-transferase P1 gene locus in pediatric tumors." PEDIATRIC RESEARCH 51.4 (April 2002): 233A-233A.
Source
wos-lite
Published In
Pediatric Research
Volume
51
Issue
4
Publish Date
2002
Start Page
233A
End Page
233A

Human Dkk-1, a gene encoding a Wnt antagonist, responds to DNA damage and its overexpression sensitizes brain tumor cells to apoptosis following alkylation damage of DNA.

The human Dkk-1 (hDkk-1) gene, a transcriptional target of the p53 tumor suppressor, encodes a powerful inhibitor of the Wnt signaling pathway and regulates the spatial patterning/morphogenesis of the mammalian central nervous system. We investigated the p53-related functions of the hDkk-1 gene by studying its response to DNA damage and its modulation of apoptosis in human glioma cells. Various chemotherapeutic and other agents that induce DNA adducts and compromise its integrity (1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), cisplatin, H(2)O(2) and UV rays) enhanced the expression of hDkk-1 significantly. The damage-induced increase in hDkk-1 mRNA levels occurred in many human tumor cell lines, irrespective of their p53 gene status. The human glioblastoma cell line, U87MG, which had undetectable hDkk-1 expression, was engineered to express moderate levels of the hDkk protein by stable transfection. The engineered cells did not show any morphological changes, but underwent marked apoptosis after ceramide treatment. Further, the DNA cross-linking drugs BCNU and cisplatin, but not the microtubule poison vincristine, induced significant cell death in U87MG/hDkk cells, and this was accompanied by altered Bcl-2/Bax expression and a reduction in the amount of telomere DNA as visualized by fluorescence in situ hybridization. These results show that hDkk-1 is a pro-apoptotic gene and suggest that it may play important roles in linking the oncogenic Wnt and p53 tumor suppressor pathways.

Authors
Shou, J; Ali-Osman, F; Multani, AS; Pathak, S; Fedi, P; Srivenugopal, KS
MLA Citation
Shou, J, Ali-Osman, F, Multani, AS, Pathak, S, Fedi, P, and Srivenugopal, KS. "Human Dkk-1, a gene encoding a Wnt antagonist, responds to DNA damage and its overexpression sensitizes brain tumor cells to apoptosis following alkylation damage of DNA." Oncogene 21.6 (January 31, 2002): 878-889.
PMID
11840333
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
21
Issue
6
Publish Date
2002
Start Page
878
End Page
889
DOI
10.1038/sj.onc.1205138

Cyclic AMP mediated GSTP1 gene activation in tumor cells involves the interaction of activated CREB-1 with the GSTP1 CRE: a novel mechanism of cellular GSTP1 gene regulation.

The human GSTP1 gene is frequently over-expressed in many human cancers and the expression increases with tumor progression and is associated with a more aggressive biology, poor patient survival, and resistance to therapy. The molecular regulation of the human GSTP1 gene during malignancy is, however, still not well understood. Recently, we reported the presence of a cAMP response element (CRE) in the 5'-region of the human GSTP1 gene, raising the possibility that the cAMP signaling pathway, frequently aberrant in human cancers, may play an important role in the transcriptional activation of the GSTP1 gene in human tumors. In this study, we report that the GSTP1 gene is an early cAMP response gene. Treatment of cells of the human lung carcinoma cell line, Calu-6, with 25 microM forskolin to activate the cAMP pathway resulted in a rapid and significant (sevenfold after 30 min) increase in GSTP1 gene transcripts, which peaked at 12-fold after 4 h. The forskolin-activated GSTP1 transcription in Calu-6 cells was suppressed dose-dependently by a 2-h pre-treatment with 0.1, 1.0, and 10 microM of the adenylate cyclase inhibitor, 2', 5'-dideoxyadenosine. Western blot analysis showed a rapid, fivefold increase, in GSTP1 protein levels after treatment with 25 microM forskolin, with a peak at 2 h post-treatment. The levels of phosphorylated CRE (Ser133) binding protein-1 (CREB-1) increased rapidly, sevenfold at 30 min, and reached 10-fold at 4 h following forskolin treatment. Intracellular cAMP levels also increased rapidly reaching 12-fold at 30 min. Gel mobility shift and supershift assays and DNase/footprinting analyses demonstrated that CREB-1 bZIP and CREB-containing nuclear extracts recognized the GSTP1 CRE with high affinity and specificity. Binding of CREB-1 bZIP to the GSTP1 CRE was abolished when the GSTP1 CRE sequence 5'-CGTCA-3', was mutated at the core nucleotides. Finally, transfection studies using luciferase plasmid constructs showed the GSTP1 CRE to be required for the cAMP-activated gene expression. Together, these findings describe a novel cAMP- and CREB-1-mediated mechanism of transcriptional regulation of the GSTP1 gene and suggest that this may be an important mechanism underlying the increased GSTP1 expression observed in tumors with an aberrant cAMP signaling pathway and in normal cells under conditions of stress, associated with increased intracellular cAMP.

Authors
Lo, H-W; Ali-Osman, F
MLA Citation
Lo, H-W, and Ali-Osman, F. "Cyclic AMP mediated GSTP1 gene activation in tumor cells involves the interaction of activated CREB-1 with the GSTP1 CRE: a novel mechanism of cellular GSTP1 gene regulation." J Cell Biochem 87.1 (2002): 103-116.
PMID
12210727
Source
pubmed
Published In
Journal of Cellular Biochemistry
Volume
87
Issue
1
Publish Date
2002
Start Page
103
End Page
116
DOI
10.1002/jcb.10275

Minimal and inducible regulation of tissue factor pathway inhibitor-2 in human gliomas

Tissue factor pathway inhibitor-2 (TFPI-2), a serine protease inhibitor abundant in the extra cellular matrix, is highly expressed in non-invasive cells but undetectable levels in highly invasive human glioma cells. The mechanisms responsible for its transcriptional regulation are not well elucidated. In this study, we made several deletion constructs from a 3.6 kb genomic fragment from Hs683 cells containing the 5′-flanking region of the TFPI-2 gene, transiently transfected with these constructs into non-invasive (Hs683) and highly invasive (SNB19) human glioma cells, and assessed their expression by using a luciferase reporter gene. Three constructs showed high promoter activity (pTF5, -670 to +1; pTF6, -312 to +1; pTF2, -1511 to +1). Another construct, pTF8 (-81 to +1), showed no activity. PTF9, a variant of pTF5 in which a further 231 bp fragment (-312 to -81) was deleted, from the [-670 to +1] pTF5 region, also showed no promoter activity. Hence, (-312 to -81) this region is essential for the transcription of TFPI-2 in glioma cells. Sequencing of this promoter region revealed that it has a high G+C content, contains potential SP1 and AP1 binding motifs, and lacks canonical TATA and CAAT boxes immediately upstream of the major transcriptional initiation site, although CAAT boxes were found about -3000 bp upstream of the transcription start site. We also found a strong repressor in the region between -927 to -1181, upstream of the major transcriptional initiation site, followed by positive elements or enhancers between -1511 to -1181. These positive elements masked the silencer effect. Finally TFPI-2 was induced in Hs683 cells transfected with the pTF6 construct (-312 to +1) and stimulated with phorbol-12-myristate-13-acetate (PMA). We conclude that the -312 to + 1 region is critical for the minimal and inducible regulation of TFPI-2 in non-invasive (Hs683) and highly invasive (SNB19) human glioma cell lines.

Authors
Konduri, SD; Osman, FA; Rao, CN; Srinivas, H; Yanamandra, N; Tasiou, A; Dinh, DH; Olivero, WC; Gujrati, M; Foster, DC; Kisiel, W; Kouraklis, G; Rao, JS
MLA Citation
Konduri, SD, Osman, FA, Rao, CN, Srinivas, H, Yanamandra, N, Tasiou, A, Dinh, DH, Olivero, WC, Gujrati, M, Foster, DC, Kisiel, W, Kouraklis, G, and Rao, JS. "Minimal and inducible regulation of tissue factor pathway inhibitor-2 in human gliomas." Oncogene 21.6 (2002): 921-928.
PMID
11840337
Source
scival
Published In
Oncogene
Volume
21
Issue
6
Publish Date
2002
Start Page
921
End Page
928
DOI
10.1038/sj/onc/1204983

Down-regulation of cathepsin B expression impairs the invasive and tumorigenic potential of human glioblastoma cells.

Increases in abundance of cathepsin B transcript and protein correlate with increases in tumor grade and alterations in subcellular localization and activity of cathepsin B. The enzyme is able to degrade the components of the extracellular matrix (ECM) and activate other proteases capable of degrading ECM. To investigate the role played by this protease in the invasion of brain tumor cells, we transfected SNB19 human glioblastoma cells with a plasmid containing cathepsin B cDNA in antisense orientation. Control cells were transfected with vector alone. Clones expressing antisense cathepsin B cDNA exhibited significant reductions in cathepsin B mRNA, enzyme activity and protein compared to controls. Matrigel Invasion assay showed that the antisense-transfected cells had a markedly diminished invasiveness compared with controls. When tumor spheroids containing antisense transfected SNB19 cells expressing reduced cathepsin B were co-cultured with fetal rat brain aggregates, invasion of fetal rat brain aggregates was significantly reduced. Green Fluorescent Protein (GFP) expressing parental cells and antisense transfectants were generated for detection in mouse brain tissue without any post-chemical treatment. Intracerebral injection of SNB19 stable antisense transfectants resulted in reduced tumor formation in nude mice. These results strongly support a role for cathepsin B in the invasiveness of human glioblastoma cells and suggest cathepsin B antisense may prove useful in cancer therapy.

Authors
Mohanam, S; Jasti, SL; Kondraganti, SR; Chandrasekar, N; Lakka, SS; Kin, Y; Fuller, GN; Yung, AW; Kyritsis, AP; Dinh, DH; Olivero, WC; Gujrati, M; Ali-Osman, F; Rao, JS
MLA Citation
Mohanam, S, Jasti, SL, Kondraganti, SR, Chandrasekar, N, Lakka, SS, Kin, Y, Fuller, GN, Yung, AW, Kyritsis, AP, Dinh, DH, Olivero, WC, Gujrati, M, Ali-Osman, F, and Rao, JS. "Down-regulation of cathepsin B expression impairs the invasive and tumorigenic potential of human glioblastoma cells." Oncogene 20.28 (June 21, 2001): 3665-3673.
PMID
11439329
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
20
Issue
28
Publish Date
2001
Start Page
3665
End Page
3673
DOI
10.1038/sj.onc.1204480

Enforced expression of wild-type p53 curtails the transcription of the O(6)-methylguanine-DNA methyltransferase gene in human tumor cells and enhances their sensitivity to alkylating agents.

We used isogenic human tumor cell lines to investigate the specific and direct effects of wild-type (wt) p53 on the expression of O(6)-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein that confers tumor resistance to many anticancer alkylating agents. A p53-null, MGMT-proficient lung tumor cell line (H1299) was engineered to express wt p53 in a tetracycline-regulated system. High levels of p53 induction achieved by tetracycline withdrawal were accompanied by G(1) cell cycle arrest without significant apoptosis in this cell line. p53 accumulation resulted in a gradual and dramatic loss of MGMT mRNA, protein, and enzyme activity, whose levels were undetectable by day 3 of induction. The loss of MGMT protein was, however, not due to its degradation because the ubiquitin-promoted in vitro degradation of MGMT, which mediates the cellular disposal of the repair protein, was not altered by p53. Run-on transcription assays revealed a significant reduction in the rate of MGMT gene transcription. The negative regulation of MGMT expression by wt p53 was confirmed in two other human isogenic cell lines, namely, the GM47.23 glioblastoma, which contains a dexamethasone-inducible wt p53, and the H460 lung cancer cell line, in which wt p53 had been inactivated by the human papillomavirus E6 protein. Furthermore, a panel of four human tumor cell lines, including gliomas with wt p53 status, displayed markedly lower levels of MGMT gene transcripts than those having p53 mutations. Induction of wt p53 in these models led to a 3- and 2-fold increase in sensitivity to 1,3-bis(2-chloroethyl)-1-nitrosourea and temozolomide, respectively, which generate the MGMT-repairable O(6)-alkyl adducts in DNA. These results demonstrate that p53 is a negative regulator of MGMT gene expression and can create a MGMT-depleted state in human tumors similar to that achieved by O(6)-benzylguanine, a potent inhibitor of MGMT currently undergoing clinical trials. Thus, our study exposes an additional benefit associated with p53 gene therapy and provides a strong biochemical rationale for combining the MGMT-directed alkylators with p53 gene transfer to achieve improved antitumor efficacy.

Authors
Srivenugopal, KS; Shou, J; Mullapudi, SR; Lang, FF; Rao, JS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, Shou, J, Mullapudi, SR, Lang, FF, Rao, JS, and Ali-Osman, F. "Enforced expression of wild-type p53 curtails the transcription of the O(6)-methylguanine-DNA methyltransferase gene in human tumor cells and enhances their sensitivity to alkylating agents." Clin Cancer Res 7.5 (May 2001): 1398-1409.
PMID
11350911
Source
pubmed
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
7
Issue
5
Publish Date
2001
Start Page
1398
End Page
1409

Adenovirus-mediated antisense urokinase-type plasminogen activator receptor gene transfer reduces tumor cell invasion and metastasis in non-small cell lung cancer cell lines.

The urokinase-type plasminogen activator (uPA) and its receptor (uPAR) play an important role in the proteolytic cascade involved in the metastasis of lung and other cancers. We report that the reduction in uPAR levels produced by an antisense strategy using an adenovirus construct (Ad-uPAR) in H1299 cells, an invasive human lung cancer cell line that produces high levels of uPAR, resulted in a decrease of uPAR levels to 80-90% of those seen in cells infected with mock or adenovirus (Ad)-cytomegalovirus vector controls. In addition, increasing the multiplicity of infection from 25 to 200 caused a corresponding decrease in the level of uPAR protein within 5 days of treatment, as shown by Western blot analysis. Furthermore, the in vitro translation of total RNA levels of Ad-uPAR-infected H1299 cells in a rabbit reticulocyte lysate system caused a 50-70% decrease in uPAR immunoprecipitate in Ad-uPAR-infected cells relative to the levels in cells of mock and vector controls. The Matrigel invasion assay showed the invasion of H1299 cells and A549 cells infected with Ad-uPAR to be decreased by 70% relative to mock- and vector-infected controls. Infection of tumor cells with Ad-uPAR before implantation significantly reduced the incidence of lung metastasis by 85% as compared with the control virus-infected cells injected into nude mice through the tail vein. Our collective results show that the uPAR system is a potential target of treatment for lung cancers.

Authors
Lakka, SS; Rajagopal, R; Rajan, MK; Mohan, PM; Adachi, Y; Dinh, DH; Olivero, WC; Gujrati, M; Ali-Osman, F; Roth, JA; Yung, WK; Kyritsis, AP; Rao, JS
MLA Citation
Lakka, SS, Rajagopal, R, Rajan, MK, Mohan, PM, Adachi, Y, Dinh, DH, Olivero, WC, Gujrati, M, Ali-Osman, F, Roth, JA, Yung, WK, Kyritsis, AP, and Rao, JS. "Adenovirus-mediated antisense urokinase-type plasminogen activator receptor gene transfer reduces tumor cell invasion and metastasis in non-small cell lung cancer cell lines." Clin Cancer Res 7.4 (April 2001): 1087-1093.
PMID
11309361
Source
pubmed
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
7
Issue
4
Publish Date
2001
Start Page
1087
End Page
1093

The DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents.

Authors
Ali-Osman, F; Srivenugopal, K; Sawaya, R
MLA Citation
Ali-Osman, F, Srivenugopal, K, and Sawaya, R. "The DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents." N Engl J Med 344.9 (March 1, 2001): 687-. (Letter)
PMID
11229339
Source
pubmed
Published In
The New England journal of medicine
Volume
344
Issue
9
Publish Date
2001
Start Page
687

Genetic polymorphism at the glutathione S-transferase (GST) P1 locus is a breast cancer risk modifier.

The isolation of full-length cDNAs of naturally occurring GSTP1 gene variants, and the demonstration that these alleles are distributed in the normal population, have provided conclusive evidence that the human GSTP1 gene locus is polymorphic and that specific GSTP1 alleles may be associated with different risk for cancers or other diseases. Recent data have indicated that the different GSTP1 alleles encode proteins with different enzymatic activities against carcinogens. In this case-control study, we examined the effect of the GSTP1 genetic polymorphism and its interaction with other factors to determine breast cancer risk. GSTP1 and GSTM1 genotypes of 220 breast cancer patients and 196 controls, all residents of western France, were examined. Data on menopausal status and family cancer history were obtained from 195 patients and 147 controls. Exons 5 and 6 of the GSTP1 gene, which contain the polymorphic nucleotide transitions, were analyzed by DNA polymerase chain reaction-restriction fragment length polymorphism to distinguish between the GSTP1 alleles. In the control population, GSTP1 allelic frequencies were 64.3%, 26.0% and 9.7%, respectively, for GSTP1*A, GSTP1*B and GSTP1*C. In the breast cancer patients, the frequencies were 67.9% for GSTP1*A, 26.8% for GSTP1*B and 5.3% for GSTP1*C. In multivariate analysis, breast cancer risk increased by 7.7-fold (p < 0.001) in women with a family history of cancers and 2.18-fold (p = 0.026) in non-GSTP1*C individuals. GSTM1 genotypes did not emerge as risk factor. Our results show that in addition to well-known risk factors, in particular, a family history of cancer, GSTP1 allelopolymorphism is a significant modifier of breast cancer risk. The results also suggest a protective role against breast cancer for the GSTP1*C allele.

Authors
Maugard, CM; Charrier, J; Pitard, A; Campion, L; Akande, O; Pleasants, L; Ali-Osman, F
MLA Citation
Maugard, CM, Charrier, J, Pitard, A, Campion, L, Akande, O, Pleasants, L, and Ali-Osman, F. "Genetic polymorphism at the glutathione S-transferase (GST) P1 locus is a breast cancer risk modifier." Int J Cancer 91.3 (February 1, 2001): 334-339.
PMID
11169956
Source
pubmed
Published In
International Journal of Cancer
Volume
91
Issue
3
Publish Date
2001
Start Page
334
End Page
339

The human glutathione S-transferase P1 (GSTP1) gene is transactivated by cyclic AMP (cAMP) via a cAMP response element (CRE) proximal to the transcription start site

The human GSTP1 gene is frequently up-regulated in human malignancies and is associated with resistance to chemotherapy and an aggressive biology. Presently, however, the molecular mechanisms involved in the regulation of this gene are not well understood. We report here the transcriptional activation of the human GSTP1 gene by the second messenger, cAMP, in human tumor cells and provide evidence that this occurs via a CRE and the AP-1 site in the 5′-regulatory region of the GSTP1 gene. The data support cAMP signaling pathways in mechanisms of GSTP1 gene regulation. © 2001 Elsevier Science Ireland Ltd. All rights reserved.

Authors
Lo, H-W; Ali-Osman, F
MLA Citation
Lo, H-W, and Ali-Osman, F. "The human glutathione S-transferase P1 (GSTP1) gene is transactivated by cyclic AMP (cAMP) via a cAMP response element (CRE) proximal to the transcription start site." Chemico-Biological Interactions 133.1-3 (2001): 320-321.
Source
scival
Published In
Chemico-Biological Interactions
Volume
133
Issue
1-3
Publish Date
2001
Start Page
320
End Page
321

The DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents [1] (multiple letters)

Authors
Buckner, JC; Moynihan, TJ; Quinn, DI; Schlegel, U; Ali-Osman, F; Srivenugopal, K; Sawaya, R; Esteller, M; Herman, JG; Weinstein, JN
MLA Citation
Buckner, JC, Moynihan, TJ, Quinn, DI, Schlegel, U, Ali-Osman, F, Srivenugopal, K, Sawaya, R, Esteller, M, Herman, JG, and Weinstein, JN. "The DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents [1] (multiple letters)." New England Journal of Medicine 344.9 (2001): 686-688.
PMID
11229337
Source
scival
Published In
The New England journal of medicine
Volume
344
Issue
9
Publish Date
2001
Start Page
686
End Page
688
DOI
10.1056/NEJM200103013440914

Selective suppression of matrix metalloproteinase-9 in human glioblastoma cells by antisense gene transfer impairs glioblastoma cell invasion.

Increased expression of matrix metalloproteinases (MMPs) has been associated with human glioblastoma tumor progression. In this study, we sought to down-regulate MMP-9 expression by stably transfecting a high-grade glioblastoma cell line with a plasmid vector capable of expressing an antisense transcript complementary to a 528-bp segment at the 5' end of human MMP-9 cDNA. Stable transfectants were obtained through selection with G418. Of the clones transfected with vector, sense, and antisense constructs, Northern blotting, Western blotting, and gelatin zymography showed that MMP-9 expression was significantly reduced only in the antisense-transfected cells. A Matrigel invasion assay revealed marked reductions in invasiveness for the antisense clones relative to the parental, vector, and sense clones. Cocultures of tumor spheroids and fetal rat brain aggregates showed that the antisense-transfected stable clones showed no invasion of the rat brain aggregates; in contrast, 90% of the parental, vector, and sense clones invaded the rat brain aggregates. Intracerebral injection of antisense stable transfectants in nude mice produced no tumors or very small tumors, but intracerebral injection of parental or vector clones did produce tumors. These results suggest that MMP-9 expression is essential for the invasiveness of glioblastoma cells.

Authors
Kondraganti, S; Mohanam, S; Chintala, SK; Kin, Y; Jasti, SL; Nirmala, C; Lakka, SS; Adachi, Y; Kyritsis, AP; Ali-Osman, F; Sawaya, R; Fuller, GN; Rao, JS
MLA Citation
Kondraganti, S, Mohanam, S, Chintala, SK, Kin, Y, Jasti, SL, Nirmala, C, Lakka, SS, Adachi, Y, Kyritsis, AP, Ali-Osman, F, Sawaya, R, Fuller, GN, and Rao, JS. "Selective suppression of matrix metalloproteinase-9 in human glioblastoma cells by antisense gene transfer impairs glioblastoma cell invasion." Cancer Res 60.24 (December 15, 2000): 6851-6855.
PMID
11156378
Source
pubmed
Published In
Cancer Research
Volume
60
Issue
24
Publish Date
2000
Start Page
6851
End Page
6855

Effects of radiation on the levels of MMP-2, MMP-9 and TIMP-1 during morphogenic glial-endothelial cell interactions.

Radiation-induced damage to the central nervous system (CNS) is believed to target glial or endothelial cells or both, although the pathophysiology of the process is poorly understood. We therefore used a coculture system, in which glioblastoma SNB19 cells induced bovine retinal endothelial (BRE) cells to form capillary-like structures, to examine the role of ionizing radiation in modulating the production of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase-1 (TIMP-1). In particular, we irradiated both BRE cells and cocultures of BRE and SNB19 cells with a single dose of X-rays and then estimated the levels of MMP-2, MMP-9 and TIMP-1. Gelatin zymography revealed a continuous increase in the levels of MMP-2 and MMP-9 during capillary-like structure formation. Of note, the levels of both MMP-2 and MMP-9 were markedly higher in irradiated cocultures at 72 hr after irradiation than in untreated cocultures. Northern blot analysis also demonstrated an increased expression of MMP-9 mRNA in the irradiated cocultures. In addition, TIMP-1 mRNA and protein levels increased up to 48 hr in both irradiated and nonirradiated BRE cells and in nonirradiated cocultures, but there was a significant decrease in the TIMP-1 mRNA and protein levels in irradiated cocultures. It takes about 72 hr for capillaries to form in nonirradiated cocultures, but these capillary networks fail to form in endothelial cells in irradiated cocultures. These findings establish that radiation differentially affects the production of MMP-2, MMP-9 and TIMP-1 during glial-endothelial morphogenesis and suggest mechanisms by which microvessels in the CNS respond to radiation.

Authors
Nirmala, C; Jasti, SL; Sawaya, R; Kyritsis, AP; Konduri, SD; Ali-Osman, F; Rao, JS; Mohanam, S
MLA Citation
Nirmala, C, Jasti, SL, Sawaya, R, Kyritsis, AP, Konduri, SD, Ali-Osman, F, Rao, JS, and Mohanam, S. "Effects of radiation on the levels of MMP-2, MMP-9 and TIMP-1 during morphogenic glial-endothelial cell interactions." Int J Cancer 88.5 (December 1, 2000): 766-771.
PMID
11072246
Source
pubmed
Published In
International Journal of Cancer
Volume
88
Issue
5
Publish Date
2000
Start Page
766
End Page
771

DNA repair protein O6-alkylguanine-DNA alkyltransferase is phosphorylated by two distinct and novel protein kinases in human brain tumour cells.

We showed recently that human O(6)-alkylguanine-DNA alkyltransferase (AGT), an important target for improving cancer chemotherapy, is a phosphoprotein and that phosphorylation inhibits its activity [Srivenugopal, Mullapudi, Shou, Hazra and Ali-Osman (2000) Cancer Res. 60, 282-287]. In the present study we characterized the cellular kinases that phosphorylate AGT in the human medulloblastoma cell line HBT228. Crude cell extracts used Mg(2+) more efficiently than Mn(2+) for phosphorylating human recombinant AGT (rAGT) protein. Both [gamma-(32)P]ATP and [gamma-(32)P]GTP served as phosphate donors, with the former being twice as efficient. Specific components known to activate protein kinase A, protein kinase C and calmodulin-dependent kinases did not stimulate the phosphorylation of rAGT. Phosphoaminoacid analysis after reaction in vitro with ATP or GTP showed that AGT was modified at the same amino acids (serine, threonine and tyrosine) as in intact HBT228 cells. Although some of these properties pointed to casein kinase II as a candidate enzyme, known inhibitors and activators of casein kinase II did not affect rAGT phosphorylation. Fractionation of the cell extracts on poly(Glu/Tyr)-Sepharose resulted in the adsorption of an AGT kinase that modified the tyrosine residues and the exclusion of a fraction that phosphorylated AGT on serine and threonine residues. In-gel kinase assays after SDS/PAGE and non-denaturing PAGE revealed the presence of two AGT kinases of 75 and 130 kDa in HBT228 cells. The partly purified tyrosine kinase, identified as the 130 kDa enzyme by the same assays, was strongly inhibited by tyrphostin 25 but not by genestein. The tyrosine kinase used ATP or GTP to phosphorylate the AGT protein; this reaction inhibited the DNA repair activity of AGT. Evidence that the kinases might physically associate with AGT in cells was also provided. These results demonstrate that two novel cellular protein kinases, a tyrosine kinase and a serine/threonine kinase, both capable of using GTP as a donor, phosphorylate the AGT protein and affect its function. The new kinases might serve as potential targets for strengthening the biochemical modulation of AGT in human tumours.

Authors
Mullapudi, SR; Ali-Osman, F; Shou, J; Srivenugopal, KS
MLA Citation
Mullapudi, SR, Ali-Osman, F, Shou, J, and Srivenugopal, KS. "DNA repair protein O6-alkylguanine-DNA alkyltransferase is phosphorylated by two distinct and novel protein kinases in human brain tumour cells." Biochem J 351 Pt 2 (October 15, 2000): 393-402.
PMID
11023825
Source
pubmed
Published In
The Biochemical journal
Volume
351 Pt 2
Publish Date
2000
Start Page
393
End Page
402

Glutathione S-transferase GSTP1 and cyclin D1 genotypes: association with numbers of basal cell carcinomas in a patient subgroup at high-risk of multiple tumours.

We previously described associations between basal cell carcinoma (BCC) numbers and allelic variants at loci that mediate host response to ultraviolet radiation (UV). These associations were largely exerted in cases with the multiple presentation phenotype (MPP). This phenotype describes patients who present at their first or a later presentation with a cluster of BCC (2-10 new BCC). Remaining BCC cases have the single presentation phenotype (SPP) and may develop more than one BCC but only have single new lesions at any presentation. We proposed that the MPP cases comprise a high-risk group as they suffer significantly more lesions than SPP cases. We are attempting to determine, in the total BCC case group and subgroups, how many genes influence BCC numbers and their relative importance. In this study, we assessed the influence of two further candidates, glutathione S-transferase GSTP1 and cyclin D1 (CCND1), on tumour numbers in a total group of 457 patients comprising MPP and SPP cases. The relative importance of these genes in comparison with occupational UV exposure and host response (skin type) was also considered. We found that the frequencies of GSTP1 genotypes based on the Ile105 and Val105-expressing alleles and CCND1 AA, AG, GG genotypes were similar in MPP and SPP cases and that there were no significant associations between GSTP1 or CCND1 genotypes and BCC numbers in the total or SPP groups. However, in the MPP cases, GSTP1 Val105/Val105 was associated with more tumours (P = 0.05, reference GSTP1 Ile105/Ile105). Inclusion of skin type and indoor/outdoor occupation in the negative binomial regression models did not alter the associations of these genotypes with tumour numbers. DNA from 258 cases was analysed to identify GSTP1*A (Ile105-Ala114), GSTP1*B (Val105-Ala114), GSTP1*C (Val105-Val114) and GSTP1*D (Ile105-Val114). In SPP cases, there was no association between BCC numbers and GSTP1 BB, though the association with GSTP1 BC approached significance (P = 0.09). In MPP cases, GSTP1 BC was associated with BCC numbers (P = 0.03). We also found that the interaction term, GSTP1 Val105/Val105 with CCND1 AA, was associated with BCC numbers in the total (P = 0.001) and MPP (P = 0.006) but not SPP (P = 0.68) groups. In a stepwise model including GSTP1 Val105/Val105, CCND1 AA and their interaction terms as well as GSTM1, GSTT1 and CYP2D6 genotypes, skin type 1 and gender, the combination of genotypes was the best predictor of BCC numbers. These data suggest that study of further genes involved in cell-cycle control and protection from oxidative stress will be useful, particularly in high-risk subgroups.

Authors
Ramachandran, S; Hoban, PR; Ichii-Jones, F; Pleasants, L; Ali-Osman, F; Lear, JT; Smith, AG; Bowers, B; Jones, PW; Fryer, AA; Strange, RC
MLA Citation
Ramachandran, S, Hoban, PR, Ichii-Jones, F, Pleasants, L, Ali-Osman, F, Lear, JT, Smith, AG, Bowers, B, Jones, PW, Fryer, AA, and Strange, RC. "Glutathione S-transferase GSTP1 and cyclin D1 genotypes: association with numbers of basal cell carcinomas in a patient subgroup at high-risk of multiple tumours." Pharmacogenetics 10.6 (August 2000): 545-556.
PMID
10975609
Source
pubmed
Published In
Pharmacogenetics and Genomics
Volume
10
Issue
6
Publish Date
2000
Start Page
545
End Page
556

DNA methyltransferase levels and altered CpG methylation in the total genome and in the GSTP1 gene in human glioma cells transfected with sense and antisense DNA methyltransferase cDNA.

This study examines the efficacy of using plasmid expression vectors containing sense and antisense DNA MTase cDNA to both up- and downregulate intracellular DNA MTase levels in human glioma cells. The effects of the changes in MTase levels on global genomic DNA methylation and on the methylation status of CpG dinucleotides in the GSTP1 gene were determined in a glioma cell line that overexpresses the GSTP1 gene. In cells transfected with sense DNA MTase cDNA, MTase gene transcripts increased to a maximum of 2. 5-fold at 24 h, while MTase activity increased to a maximum of 3. 6-fold at 48 h. The effects of antisense MTase cDNA transfections were less pronounced, and levels of MTase gene transcripts and enzyme activity in transfectants were decreased to only, approximately, one-half the levels of controls. The alterations in DNA MTase expression were associated with corresponding changes in the level of global DNA methylation and in the methylation of the GSTP1 gene in the cells, however, with no detectable morphological or cytotoxic effects on the cells. No significant changes in GSTP1 gene expression were detected after the transfections, presumably because of the high levels of basal GSTP1 expression in the cells. Consequently, the p16 gene, known to be repressed transcriptionally by DNA methylation, was examined for the functional effects of the altered MTase levels. The results showed a 2-fold decrease in p16 gene transcripts with the sense MTase transfectants, while in the MTase antisense-transfected cells p16 transcript levels increased by 30%. Together, these results demonstrate the feasibility of using both sense and antisense DNA MTase expression vectors to regulate DNA MTase levels in glioma cells and that, over relatively short periods of time, the alterations in MTase activities are not deleterious to the cells. The system provides a model with which the role of DNA methylation in critical genes and DNA sequences can be investigated in glioma cells.

Authors
Antoun, G; Baylin, SB; Ali-Osman, F
MLA Citation
Antoun, G, Baylin, SB, and Ali-Osman, F. "DNA methyltransferase levels and altered CpG methylation in the total genome and in the GSTP1 gene in human glioma cells transfected with sense and antisense DNA methyltransferase cDNA." J Cell Biochem 77.3 (April 2000): 372-381.
PMID
10760946
Source
pubmed
Published In
Journal of Cellular Biochemistry
Volume
77
Issue
3
Publish Date
2000
Start Page
372
End Page
381

Protein phosphorylation is a regulatory mechanism for O6-alkylguanine-DNA alkyltransferase in human brain tumor cells.

The biochemical regulation of human O6-alkylguanine-DNA alkyltransferase (AGT), which determines the susceptibility of normal tissues to methylating carcinogens and resistance of tumor cells to many alkylating agents, is poorly understood. We investigated the regulation of AGT by protein phosphorylation in a human medulloblastoma cell line. Incubation of cell extracts with [gamma-32P]ATP resulted in Mg(2+)-dependent phosphorylation of the endogenous AGT. Immunoprecipitation after exposure of the cells to 32P-labeled inorganic phosphate showed that AGT exists as a phosphoprotein under physiological conditions. Western analysis and chemical stability studies showed the AGT protein to be phosphorylated at tyrosine, threonine, and serine residues. Purified protein kinase A (PKA), casein kinase II (CK II), and protein kinase C (PKC) phosphorylated the recombinant AGT protein with a stoichiometry of 0.15, 0.28, and 0.44 (mol phosphate incorporated/mol protein), respectively. Residual phosphorylation of the endogenous AGT by the PKs present in cell homogenates and phosphorylation of the recombinant AGT by purified serine/threonine kinases, PKA, PKC, and CK II reduced AGT activity by 30-65%. Conversely, dephosphorylation of cell extracts by alkaline phosphatases stimulated AGT activity. We also identified consensus phosphorylation motifs for many cellular kinases, including PKA and CK II in the AGT protein. These data provide the first and conclusive evidence of AGT phosphorylation and suggest that reversible phosphorylation may control the activity of this therapeutically important DNA repair protein in human normal and cancer cells.

Authors
Srivenugopal, KS; Mullapudi, SR; Shou, J; Hazra, TK; Ali-Osman, F
MLA Citation
Srivenugopal, KS, Mullapudi, SR, Shou, J, Hazra, TK, and Ali-Osman, F. "Protein phosphorylation is a regulatory mechanism for O6-alkylguanine-DNA alkyltransferase in human brain tumor cells." Cancer Res 60.2 (January 15, 2000): 282-287.
PMID
10667577
Source
pubmed
Published In
Cancer Research
Volume
60
Issue
2
Publish Date
2000
Start Page
282
End Page
287

Regulation of MMP-9 (type IV collagenase) production and invasiveness in gliomas by the extracellular signal-regulated kinase and jun amino-terminal kinase signaling cascades.

Our previous studies have shown that MMP-9 levels are significantly elevated during the progression of human gliomas. In the current study, we examined the role of JNK- and ERK-dependent signaling modules in the regulation of MMP-9 production and the invasive behavior of the human glioblastoma cell line SNB19, in which JNK/ERK1 is constitutively activated. SNB19 cells that were transfected with dominant-negative JNK, MEKK, and ERK1 expression vectors showed reduced MMP-9 promoter activity. In addition, conditioned medium collected from SNB19 cells transfected with these expression vectors showed diminished MMP-9 activity in the presence of phorbol myristate acetate, as determined by gelatin zymography. The cotransfection of SNB19 cells with kinase-deficient c-raf also diminished MMP-9 promoter activity. Further, in the presence of a specific inhibitor of MEKK (PD098059), the Matrigel invasion assay showed the invasiveness of dominant-negative SNB19 cells transfected with dominant-negative JNK1 or ERK1 to be remarkably reduced. In conclusion, our studies showed for the first time that MMP-9 production and the invasive behavior of SNB 19 cells are regulated by JNK- and ERK-dependent signaling modules and that interfering with either of the pathways reduces invasiveness.

Authors
Lakka, SS; Jasti, SL; Kyritsis, AP; Yung, WK; Ali-Osman, F; Nicolson, GL; Rao, JS
MLA Citation
Lakka, SS, Jasti, SL, Kyritsis, AP, Yung, WK, Ali-Osman, F, Nicolson, GL, and Rao, JS. "Regulation of MMP-9 (type IV collagenase) production and invasiveness in gliomas by the extracellular signal-regulated kinase and jun amino-terminal kinase signaling cascades." Clin Exp Metastasis 18.3 (2000): 245-252.
PMID
11315098
Source
pubmed
Published In
Clinical & Experimental Metastasis
Volume
18
Issue
3
Publish Date
2000
Start Page
245
End Page
252

Modulation of endothelial cell morphogenesis in vitro by MMP-9 during glial-endothelial cell interactions.

The purpose of this study was to investigate the roles of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the formation of capillary structures by human brain microvascular endothelial cells cocultured with SNB19 glioblastoma cells. Unstimulated cocultures did not form capillaries and produce MMP-9 but stimulation with the protein kinase C (PKC) activator 4-phorbol-12-myristate 13-acetate (PMA) produced MMP-9 and capillary networks. Addition of recombinant MMP-9 increased capillary formation. Anti-MMP-9 antibodies, TIMP-1, the synthetic MMPs inhibitor Batimastat (BB-94), and the PKC inhibitor calphostin-C all reduced MMP-9 activity and capillary network formation in these cocultures. Cytochalasin-D in the presence of PMA suppressed MMP-9 expression and capillary formation, but colchicine-B had no such effect. Finally, PMA-induced MMP-9 expression and capillary formation were inhibited by the MEKK-specific inhibitor PD98059. These results suggest that MMP-9 is important in endothelial cell morphogenesis and the formation of capillaries in glial/endothelial cocultures in vitro.

Authors
Chandrasekar, N; Jasti, S; Alfred-Yung, WK; Ali-Osman, F; Dinh, DH; Olivero, WC; Gujrati, M; Kyritsis, AP; Nicolson, GL; Rao, JS; Mohanam, S
MLA Citation
Chandrasekar, N, Jasti, S, Alfred-Yung, WK, Ali-Osman, F, Dinh, DH, Olivero, WC, Gujrati, M, Kyritsis, AP, Nicolson, GL, Rao, JS, and Mohanam, S. "Modulation of endothelial cell morphogenesis in vitro by MMP-9 during glial-endothelial cell interactions." Clin Exp Metastasis 18.4 (2000): 337-342.
PMID
11448065
Source
pubmed
Published In
Clinical & Experimental Metastasis
Volume
18
Issue
4
Publish Date
2000
Start Page
337
End Page
342

Molecular modeling based design of novel anticancer therapeutics that target the active sites of polymorphic GSTP1 proteins.

Authors
Ali-Osman, F; Buolanwini, J
MLA Citation
Ali-Osman, F, and Buolanwini, J. "Molecular modeling based design of novel anticancer therapeutics that target the active sites of polymorphic GSTP1 proteins." CLINICAL CANCER RESEARCH 5 (November 1999): 3841S-3841S.
Source
wos-lite
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
5
Publish Date
1999
Start Page
3841S
End Page
3841S

Amplification of telomeric DNA directly correlates with metastatic potential of human and murine cancers of various histological origin.

Telomeres, repeated DNA sequences (T2AG3)n that guard the ends of chromosomes, serve as a checkpoint for cell-cycle progression and regulate cell senescence and apoptosis. Loss of the telomeric repeats promotes genomic instability, which is the hallmark of most cancer cells. Whether this loss differs among tumor cells with malignant potential is unknown and was the goal of this study. An all-human telomeric DNA probe was used to perform fluorescence in situ hybridization (FISH) and the telomeric signals in interphase nuclei were quantitated using a computer software package. Southern blot analysis was carried out to measure terminal restriction fragment length (TRFL) in multiple cancer cell lines, including nonmetastatic and metastatic human breast, lung, prostate, colon, brain, and renal carcinomas, as well as human and murine melanoma clones and somatic cell hybrids. The metastatic capability of all cell lines, clones and somatic cell hybrids was evaluated subsequent to orthotopic implantation into nude mice. FISH preparations with telomeric DNA probes showed that the mean percent telomeric area in the metastatic nuclei was significantly greater than their nonmetastatic counterparts and Southern blotting in selected samples confirmed our findings. These data suggest that amplification of telomeres is directly correlated with invasive and metastatic potential of murine or human tumor cells.

Authors
Multani, AS; Ozen, M; Sen, S; Mandal, AK; Price, JE; Fan, D; Radinsky, R; Ali-Osman, F; Von Eschenbach, AC; Fidler, IJ; Pathak, S
MLA Citation
Multani, AS, Ozen, M, Sen, S, Mandal, AK, Price, JE, Fan, D, Radinsky, R, Ali-Osman, F, Von Eschenbach, AC, Fidler, IJ, and Pathak, S. "Amplification of telomeric DNA directly correlates with metastatic potential of human and murine cancers of various histological origin." Int J Oncol 15.3 (September 1999): 423-429.
PMID
10427120
Source
pubmed
Published In
International journal of oncology
Volume
15
Issue
3
Publish Date
1999
Start Page
423
End Page
429

Differential transactivation of the hGSTP1 promoter by individual direct/everted repeat retinoic acid response elements in intron 5 of the hGSTP1 gene

Authors
Lo, HW; Ali-Osman, F
MLA Citation
Lo, HW, and Ali-Osman, F. "Differential transactivation of the hGSTP1 promoter by individual direct/everted repeat retinoic acid response elements in intron 5 of the hGSTP1 gene." Clinical Chemistry and Enzymology Communications 8.4-6 (1999): 293-302.
Source
scival
Published In
Clinical Chemistry and Enzymology Communications
Volume
8
Issue
4-6
Publish Date
1999
Start Page
293
End Page
302

In vitro repair synthesis of BCNU-induced DNA damage.

The nitrosoureas including BCNU are potent chemotherapeutic drugs and have been used extensively for treatment of brain tumors and other neoplasias but the mechanisms of action for the DNA lesions created and their repair are still unclear. We have recently determined the in vitro repair of BCNU-treated DNA with cellular extracts and with DNA modifying enzymes. BCNU not only caused an increase in breaks in plasmid DNA, but an increase in cross-linked DNA was also observed after restriction enzyme digestion followed by gel electrophoresis. When HeLa cell-extracts were incubated with BCNU-treated DNA, 5-10 fold increases in DNA repair synthesis were observed as compared with untreated control. Substantial increases in 5'OH and 3'OH sites of the breaks were also found in BCNU-treated DNA as determined by the 10-20 fold increases in labeling with T4-DNA kinase and by endogenous polymerases, while the amount of ligatable sites were at a minimal. When the repair capacity of two glioma cell lines (UWR1 and UWR3) with differential BCNU sensitivity, and cells from a chromosomal breakage disease, Bloom's syndrome (BS), were assessed, the activities of the two glioma cells were about 20-30% of the normal lymphoblastoid cells and HeLa cells, whereas no difference was observed in BS cells. However, differential patterns of DNA bands were observed in the glioma samples suggesting cell-type specific capacities of repair synthesis. These data are in accordance with the concept that BCNU creates multiple DNA lesions and suggests different cell types may develop a variety of repair capabilities.

Authors
Chan, JY; Ali-Osman, F
MLA Citation
Chan, JY, and Ali-Osman, F. "In vitro repair synthesis of BCNU-induced DNA damage." Cancer Biochem Biophys 16.3 (October 1998): 273-286.
PMID
10072211
Source
pubmed
Published In
Cancer biochemistry biophysics
Volume
16
Issue
3
Publish Date
1998
Start Page
273
End Page
286

Translational inhibition of messenger RNA of the human pi class glutathione S-transferase by antisense oligodeoxyribonucleotides.

In this study, a T7 plasmid expression vector containing the cDNA of a variant human GST-pi gene, hGSTP1*C, was used to examine the translational inhibition of the GST-pi mRNA with antisense deoxyribonucleotides (AS-ONs), and to investigate the dependency of the inhibition on ribonuclease (RNAse) H, AS-ON and target mRNA sequence specificity and AS-ON back bone modification. Translational inhibition of hGSTP1*C mRNA showed significant AS-ON concentration-dependency and was both target mRNA and AS-ON sequence specific. Fully modified phosphoromonthioate AS-ONs were less inhibitory than their partial phosphoromonthioate analogs; unmodified AS-ONs were inactive. RNAse H enhanced the translational inhibition by AS-ON specific to the translation initiation region mRNA, and was associated with cleavage of the target mRNA at the site of AS-ON:mRNA hybridization. AS-ONs directed to the A-->G and C-->T transitions, unique to hGSTP1*C, were more RNAse H-dependent than AS-ONs directed against the translation initiation site, indicating a greater involvement of RNAse H-dependent mRNA cleavage in the mechanism of translational inhibition by AS-ON at the polymorphic site. These data suggest that AS-ONs provide a potentially effective means of specific down-regulation of the human GST-pi gene, and demonstrate that the sites of GST-pi gene allelo-polymorphism can be targeted to translationally down-regulate the different GST-pi gene variants, specifically and differentially targeted.

Authors
Keller, C; Ali-Osman, F
MLA Citation
Keller, C, and Ali-Osman, F. "Translational inhibition of messenger RNA of the human pi class glutathione S-transferase by antisense oligodeoxyribonucleotides." Chem Biol Interact 111-112 (April 24, 1998): 307-323.
PMID
9679562
Source
pubmed
Published In
Chemico-Biological Interactions
Volume
111-112
Publish Date
1998
Start Page
307
End Page
323

Structure of the human allelic glutathione S-transferase-pi gene variant, hGSTP1 C, cloned from a glioblastoma multiforme cell line.

We recently reported the cloning of full-length cDNAs corresponding to mRNAs of three GST-pi genes, hGSTP1*A, hGSTP1*B and hGSTP1*C, as well as, the isolation of the full-length hGSTP1*C, of the human glutathione S-transferase-pi (GST-pi) gene that is characterized by a A-->G transition at +1404 in exon 5 and a C-->T transition at +2294 in exon 6. Although the promoter of the isolated gene was identical to that of the previously described GST-pi gene isolated from the MCF 7 and the HPB-ALL cell lines, both of which were hGSTP1*A, a number of structural differences were observed, including, nucleotide transitions, transversions, deletions and insertions, some of which created new restriction enzyme cleavage sites. A guanine insertion in the insulin response element, IRE, in intron 1 created an additional site for 5'-cytosine methylation. Seven repeat retinoic acid response element (RARE) consensus half sites, A(G)GG(T)TC(G)A at +1521 to +1644 were identified in the cloned hGSTP1*C. Five of the RARE half-sites had the minimal spacer nucleotide requirement for functionality and DNA mobility shift analysis with different pairs of the RARE half-sites and supershift studies using antibodies against RAR-beta showed significant binding of nuclear protein complexes from RA-treated cells to these RAREs. GST-pi gene expression was increased significantly in cells transfected with the GST-pi gene and treated with all-trans RA. These results contrast with those in a previous report in which RA was shown to suppress the GST-pi promoter, and indicate a complex mechanism of RA-mediated GST-pi gene regulation in tumor cells.

Authors
Lo, HW; Ali-Osman, F
MLA Citation
Lo, HW, and Ali-Osman, F. "Structure of the human allelic glutathione S-transferase-pi gene variant, hGSTP1 C, cloned from a glioblastoma multiforme cell line." Chem Biol Interact 111-112 (April 24, 1998): 91-102.
PMID
9679546
Source
pubmed
Published In
Chemico-Biological Interactions
Volume
111-112
Publish Date
1998
Start Page
91
End Page
102

Special issue: Glutathione and glutathione-linked enzymes in human cancer and other diseases - Preface

Authors
Ali-Osman, F; Tew, KD; Strange, RC
MLA Citation
Ali-Osman, F, Tew, KD, and Strange, RC. "Special issue: Glutathione and glutathione-linked enzymes in human cancer and other diseases - Preface." CHEMICO-BIOLOGICAL INTERACTIONS 112 (April 24, 1998): XIII-XIV.
Source
wos-lite
Published In
Chemico-Biological Interactions
Volume
112
Publish Date
1998
Start Page
XIII
End Page
XIV

Nitric oxide and neopterin levels and clinical response in stage III melanoma patients receiving concurrent biochemotherapy.

The combination of cisplatin-based chemotherapy with interleukin-2 (IL-2) and interferon-alpha (IFN-alpha), referred to as biochemotherapy, has produced overall response rates of greater than 50% in advanced melanoma patients, with durable complete responses in the range of 5-10%. The mechanism of action of biochemotherapy is unknown. Preclinical work suggests synergistic interactions between the cytotoxic agents, especially cisplatin, and the biological agents in killing melanoma cells. Immune effector cells activated by the components of the biochemotherapy may also be involved, as direct cytotoxic effectors and/or as sources of secondary cytokines, which can induce nitric oxide (NO) production in a wide variety of cell types. In addition, high levels of neopterin, a marker of monocyte/macrophage activation, have been found in patients undergoing immunotherapy or biochemotherapy for melanoma. Based on these data, we hypothesized that the degree of elevation of serum NO metabolic products and neopterin during treatment would correlate with the response to biochemotherapy in melanoma patients. Blood samples were obtained before and during preoperative biochemotherapy with cisplatin, vinblastine, dacarbazine, IL-2 and IFN-alpha in 45 melanoma patients with locoregionally advanced disease. NO was measured as nitrite after enzymatic reduction, using the colorimetric assay of Griess, and neopterin was measured by radioimmunoassay. Our results demonstrate a higher day 5 nitrite level (of borderline statistical significance, P = 0.057) in major responders to the therapy than in those who did not achieve a major response, while there was no difference in the elevation in neopterin level during therapy between major and non-major responders. These results suggest that induction of NO during biochemotherapy may be playing a role in the mechanism of action of this therapy, while the role of monocyte/macrophage activation is still in question.

Authors
Anderson, CM; Buzaid, AC; Sussman, J; Lee, JJ; Ali-Osman, F; Braunschweiger, PG; Plager, C; Bedikian, A; Papadopoulos, N; Eton, O; Legha, SS; Grimm, EA
MLA Citation
Anderson, CM, Buzaid, AC, Sussman, J, Lee, JJ, Ali-Osman, F, Braunschweiger, PG, Plager, C, Bedikian, A, Papadopoulos, N, Eton, O, Legha, SS, and Grimm, EA. "Nitric oxide and neopterin levels and clinical response in stage III melanoma patients receiving concurrent biochemotherapy." Melanoma Res 8.2 (April 1998): 149-155.
PMID
9610868
Source
pubmed
Published In
Melanoma Research
Volume
8
Issue
2
Publish Date
1998
Start Page
149
End Page
155

DNA damage in peripheral blood mononuclear cells correlates with response to biochemotherapy in melanoma.

The combination of cisplatin-based chemotherapy with interleukin-2 (IL-2) and interferon, referred to as biochemotherapy, has shown encouraging results in patients with advanced melanoma. Toxicity is high, however and no objective parameters exist to distinguish between patients who are likely to respond and those who are not. The purpose of this pilot study was to determine whether in vitro cisplatin-induced damage to the glutathione S-transferase-pi (GST-pi) gene in peripheral blood mononuclear cells (PBMCs) before therapy correlated with the histological response in melanoma patients with local-regional metastases who received concurrent biochemotherapy before definitive surgery. Before therapy, PBMCs from 16 patients were exposed to cisplatin at concentrations of 25, 50 or 100 microM for 3 h and the extent of damage to the GST-pi gene was quantitated by polymerase chain reaction (PCR). Patients were subsequently treated on a biochemotherapy regimen consisting of cisplatin 20 mg/m2 intravenously (i.v.) on days 1-4, vinblastine 1.5 mg/m2 i.v. on days 1-4, dacarbazine 800 mg/m2 i.v. on day 1, IL-2 9 MIU/m2 per day i.v. by continuous infusion on days 1-4 (total of 96 h), and interferon alpha2a 5 MU/m2 subcutaneously on days 1-5. The 16 patients were categorized into two groups: major responders (n = 7) and non-major responders (n = 9). Although we observed a wide interpatient variation, a statistically significant correlation existed between the histological response and the degree of DNA damage caused in the PBMCs at all three cisplatin concentrations tested (P = 0.024 for 25 microM; P = 0.036 for 50 microM; P = 0.007 for 100 microM). Our pilot study suggests that determination of in vitro cisplatin-induced DNA damage using a gene-specific PCR assay may be useful in predicting the histological response to biochemotherapy.

Authors
Buzaid, AC; Ali-Osman, F; Akande, N; Grimm, EA; Lee, JJ; Bedikian, A; Eton, O; Papadopoulos, N; Plager, C; Legha, SS; Benjamin, RS
MLA Citation
Buzaid, AC, Ali-Osman, F, Akande, N, Grimm, EA, Lee, JJ, Bedikian, A, Eton, O, Papadopoulos, N, Plager, C, Legha, SS, and Benjamin, RS. "DNA damage in peripheral blood mononuclear cells correlates with response to biochemotherapy in melanoma." Melanoma Res 8.2 (April 1998): 145-148.
PMID
9610867
Source
pubmed
Published In
Melanoma Research
Volume
8
Issue
2
Publish Date
1998
Start Page
145
End Page
148

Antisense oligonucleotide downregulation of human glutathione S-transferase-PI gene expression for enhanced efficacy of cancer chemotherapy

Authors
Ali-Osman, F
MLA Citation
Ali-Osman, F. "Antisense oligonucleotide downregulation of human glutathione S-transferase-PI gene expression for enhanced efficacy of cancer chemotherapy." International Journal of Pediatric Hematology/Oncology 5.1 (1998): 48-49.
Source
scival
Published In
International Journal of Pediatric Hematology/Oncology
Volume
5
Issue
1
Publish Date
1998
Start Page
48
End Page
49

Genomic cloning of hGSTP1*C, an allelic human Pi class glutathione S-transferase gene variant and functional characterization of its retinoic acid response elements.

The complete hGSTP1*C, consisting of 7 exons and 6 introns contained in 3116 base pairs, was isolated from a cosmid genomic library of a glioblastoma multiforme cell line. Although the promoter of hGSTP1*C was identical to that of the previously reported GST-Pi gene, several of its structural features had not been previously described. These include several nucleotide transitions and transversions. Transitions of A --> G at +1404 and C --> T at +2294 in exons 5 and 6, respectively, changed codons Ile104 to Val104 and Ala113 to Val113. The gene also contained a guanine insertion at +51 in the insulin response element in intron 1 and six tandem repeats and one palindromic retinoic acid response element (RARE) consensus half-sites, A(G)GG(T)TC(G)A in intron 5. Retinoic acid (RA) treatment increased GST-Pi gene expression significantly in MGR3 cells. GST-Pi gene constructs with and without RARE deletion were used to show the RARE requirement for GST-Pi gene induction by RA. The isolation of the hGSTP1*C gene and the evidence that it contains functional RAREs should contribute to a better understanding of the molecular regulation of the GST-Pi gene in human cells.

Authors
Lo, HW; Ali-Osman, F
MLA Citation
Lo, HW, and Ali-Osman, F. "Genomic cloning of hGSTP1*C, an allelic human Pi class glutathione S-transferase gene variant and functional characterization of its retinoic acid response elements." J Biol Chem 272.52 (December 26, 1997): 32743-32749.
PMID
9407047
Source
pubmed
Published In
The Journal of biological chemistry
Volume
272
Issue
52
Publish Date
1997
Start Page
32743
End Page
32749

Prognostic significance of glutathione S-transferase pi expression and subcellular localization in human gliomas.

The glutathione S-transferase (GST)-pi gene is overexpressed in many human cancers and preneoplastic lesions and is associated with failure of cancer chemotherapy and poor patient survival. Although GST-pi overexpression in tumors of the central nervous system has been observed, the prognostic and/or clinical relevance of this overexpression has, to date, not been investigated. In this study, we analyzed the level of GST-pi expression and its subcellular localization in 61 primary gliomas and correlated the results with tumor histology, patient age, and patient survival. We observed a strong positive correlation between the level of GST-pi expression and tumor grade and between the presence of GST-pi in glioma cell nuclei and patient age. Univariate and multivariate Cox regression analyses and Kaplan-Meier curves showed the level of GST-pi expression and its nuclear localization to be inversely correlated with patient survival. Relative risk for death of patients with high versus low tumor GST-pi expression was 3.2 (P = 0.0069) by univariate analysis and 2.6 (P = 0.036) by multivariate analysis. The relative risk of death associated with the presence of nuclear GST-pi in glioma cells was 3.9 (P = 0.0001) by univariate analysis and 4.4 (P < 0.0001) by multivariate analysis. These data indicate that high GST-pi expression in tumor cells and the presence of the GST-pi protein in tumor cell nuclei are associated with clinically more aggressive gliomas and are strong predictors of poor patient survival.

Authors
Ali-Osman, F; Brunner, JM; Kutluk, TM; Hess, K
MLA Citation
Ali-Osman, F, Brunner, JM, Kutluk, TM, and Hess, K. "Prognostic significance of glutathione S-transferase pi expression and subcellular localization in human gliomas." Clin Cancer Res 3.12 Pt 1 (December 1997): 2253-2261.
PMID
9815622
Source
pubmed
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
3
Issue
12 Pt 1
Publish Date
1997
Start Page
2253
End Page
2261

Prognostic significance of glutathione S-transferase pi expression and subcellular localization in human gliomas

Authors
Ali-Osman, F; Brunner, JM; Kutluk, TM; Hess, K
MLA Citation
Ali-Osman, F, Brunner, JM, Kutluk, TM, and Hess, K. "Prognostic significance of glutathione S-transferase pi expression and subcellular localization in human gliomas." CLINICAL CANCER RESEARCH 3.12 (December 1997): 2253-2261.
Source
wos-lite
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
3
Issue
12
Publish Date
1997
Start Page
2253
End Page
2261

Activity and distribution of the cysteine prodrug activating enzyme, 5-oxo-L-prolinase, in human normal and tumor tissues.

5-Oxo-L-prolinase (OPase), a key enzyme of the gamma-glutamyl cycle, has the ability to metabolize L-2-oxothiazolidine-4-carboxylic acid (OTC) to cysteine, and thereby increase intracellular glutathione (GSH) levels. This strategy of GSH elevation can be potentially exploited to reduce normal tissue toxicity of anticancer agents, provided that sufficient differences exist in OPase levels between normal and malignant tissues. In this study, therefore, we quantitated OPase activity in primary specimens of matched and unmatched human normal and tumor (lung, breast, kidney, colon and ovary) tissues using a newly developed non-radioactive OPase assay, based on the production of cysteine from OTC. The rank order of OPase activity in extracts of 24 normal tissues examined was kidney > lung, breast and colon > ovary. OPase activity was present in all 37 tumor samples, but at variable levels. Tumor OPase levels were generally equivalent to those in their normal tissue counterparts, with the notable exception of Wilms' tumors, which had markedly lower levels than normal kidney (P < 0.02). However, when 14 matched tumor and adjacent normal tissues were compared, OPase levels were significantly higher in normal specimens than tumors for individual patients (P < 0.005). These higher normal tissue/tumor OPase ratios suggest that OTC may be useful in decreasing normal tissue toxicity, at least, for some tissues during cancer therapy.

Authors
Srivenugopal, KS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, and Ali-Osman, F. "Activity and distribution of the cysteine prodrug activating enzyme, 5-oxo-L-prolinase, in human normal and tumor tissues." Cancer Lett 117.1 (July 15, 1997): 105-111.
PMID
9233839
Source
pubmed
Published In
Cancer Letters
Volume
117
Issue
1
Publish Date
1997
Start Page
105
End Page
111

Methylator resistance mediated by mismatch repair deficiency in a glioblastoma multiforme xenograft.

A methylator-resistant human glioblastoma multiforme xenograft, D-245 MG (PR), in athymic nude mice was established by serially treating the parent xenograft D-245 MG with procarbazine. D-245 MG xenografts were sensitive to procarbazine, temozolomide, N-methyl-N-nitrosourea, 1,3-bis(2-chloroethyl)-1-nitrosourea, 9-aminocamptothecin, topotecan, CPT-11, cyclophosphamide, and busulfan. D-245 MG (PR) xenografts were resistant to procarbazine, temozolomide, N-methyl-N-nitrosourea, and busulfan, but they were sensitive to the other agents. Both D-245 MG and D-245 MG (PR) xenografts displayed no O6-alkylguanine-DNA alkyltransferase activity, and their levels of glutathione and glutathione-S-transferase were similar. D-245 MG xenografts expressed the human mismatch repair proteins hMSH2 and hMLH1, whereas D-245 MG (PR) expressed hMLH1 but not hMSH2.

Authors
Friedman, HS; Johnson, SP; Dong, Q; Schold, SC; Rasheed, BK; Bigner, SH; Ali-Osman, F; Dolan, E; Colvin, OM; Houghton, P; Germain, G; Drummond, JT; Keir, S; Marcelli, S; Bigner, DD; Modrich, P
MLA Citation
Friedman, HS, Johnson, SP, Dong, Q, Schold, SC, Rasheed, BK, Bigner, SH, Ali-Osman, F, Dolan, E, Colvin, OM, Houghton, P, Germain, G, Drummond, JT, Keir, S, Marcelli, S, Bigner, DD, and Modrich, P. "Methylator resistance mediated by mismatch repair deficiency in a glioblastoma multiforme xenograft." Cancer Res 57.14 (July 15, 1997): 2933-2936.
PMID
9230204
Source
pubmed
Published In
Cancer Research
Volume
57
Issue
14
Publish Date
1997
Start Page
2933
End Page
2936

Effect of cisplatin and BCNU on MMP-2 levels in human glioblastoma cell lines in vitro.

Matrix metalloproteinases (MMPs) play an important role in various physiological and pathological conditions such as tissue remodeling, and cancer cell invasion and metastasis. The aim of this study was to determine the effect of the antitumor compounds cis-dichlorodiammine platinum (ii) (cisplatin) and 1, 3 bis (2-chloroethyl)-1-nitrosourea (BCNU) on 72-kDa type IV collagenase activity (MMP-2) in human gliomas. Human glioblastoma cell lines were treated with cisplatin (25 microM), and BCNU (50 microM), and the levels of MMP-2 were estimated in serum-free conditioned medium and in cell extracts at different time intervals. Gelatin zymography revealed increased levels of MMP-2 in serum-free conditioned medium and in cell extracts of untreated glioblastoma cell cultures during a 72-h period. In contrast, MMP-2 levels were significantly decreased in cisplatin-treated cells both in conditioned medium and cell extracts. However, no significant changes of MMP-2 levels were noted in BCNU-treated cells. Quantitative analysis of MMP-2 enzyme activity by densitometry and amount of MMP-2 protein by ELISA showed significantly decreased levels of MMP-2 in cisplatin-treated cells compared to BCNU and untreated glioblastoma cells. The results indicate that decreased levels of MMP-2 might represent an additional mechanism by which cisplatin provides its antineoplastic effects.

Authors
Chintala, SK; Ali-Osman, F; Mohanam, S; Rayford, A; Go, Y; Gokaslan, ZL; Gagercas, E; Venkaiah, B; Sawaya, R; Nicolson, GL; Rao, JS
MLA Citation
Chintala, SK, Ali-Osman, F, Mohanam, S, Rayford, A, Go, Y, Gokaslan, ZL, Gagercas, E, Venkaiah, B, Sawaya, R, Nicolson, GL, and Rao, JS. "Effect of cisplatin and BCNU on MMP-2 levels in human glioblastoma cell lines in vitro." Clin Exp Metastasis 15.4 (July 1997): 361-367.
PMID
9219724
Source
pubmed
Published In
Clinical & Experimental Metastasis
Volume
15
Issue
4
Publish Date
1997
Start Page
361
End Page
367

Cisplatin but not BCNU inhibits urokinase-type plasminogen activator levels in human glioblastoma cell lines in vitro.

Glioblastomas extensively invade the surrounding normal brain tissue, with a concomitant expression of various proteolytic enzymes, in particular urokinase-type plasminogen activator (uPA). In this study we used cis-diamminedichloroplatinum (cisplatin) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), commonly used anti-cancer drugs for the treatment of glioblastomas, to study the expression of uPA in three human glioblastoma cell lines in vitro. Cells were treated with 25 microM cisplatin and 50 microM BCNU, and uPA levels were estimated by fibrin zymography during a 72-h time course. Treatment of glioblastoma cells with cisplatin resulted in significantly decreased levels of uPA in serum-free conditioned medium and cell extracts, compared to BCNU-treated and untreated cell lines. Quantitative levels of uPA enzyme activity assessed by scanning laser densitometry and uPA protein by ELISA using antibody against uPA showed decreased levels of uPA in cisplatin-treated glioma cell lines relative to BCNU and untreated cell lines. Our results suggest that anti-tumor compound, cisplatin, may exert its anti-neoplastic effects by inhibiting uPA in malignant glioblastomas.

Authors
Go, Y; Chintala, SK; Rayford, A; Gagercas, E; Ali-Osman, F; Venkaiah, B; Sawaya, R; Gokaslan, Z; Nicolson, GL; Rao, JS
MLA Citation
Go, Y, Chintala, SK, Rayford, A, Gagercas, E, Ali-Osman, F, Venkaiah, B, Sawaya, R, Gokaslan, Z, Nicolson, GL, and Rao, JS. "Cisplatin but not BCNU inhibits urokinase-type plasminogen activator levels in human glioblastoma cell lines in vitro." Clin Exp Metastasis 15.4 (July 1997): 447-452.
PMID
9219734
Source
pubmed
Published In
Clinical & Experimental Metastasis
Volume
15
Issue
4
Publish Date
1997
Start Page
447
End Page
452

Molecular cloning, characterization, and expression in Escherichia coli of full-length cDNAs of three human glutathione S-transferase Pi gene variants. Evidence for differential catalytic activity of the encoded proteins.

We report the isolation of three full-length cDNAs corresponding to the mRNAs of closely related glutathione S-transferase (GST) Pi genes, designated hGSTP1*A, hGSTP1*B, and hGSTP1*C, expressed in normal cells and malignant gliomas. The variant cDNAs result from A --> G and C --> T transitions at nucleotides +313 and +341, respectively. The transitions changed codon 104 from ATC (Ile) in hGSTP1*A to GTC (Val) in hGSTP1*B and hGSTP1*C and changed codon 113 from GCG (Ala) to GTG (Val) in hGSTP1*C. Both amino changes are in the electrophile-binding active site of the GST Pi peptide. Computer modeling of the deduced crystal structures of the encoded peptides showed significant deviations in the interatomic distances of critical electrophile-binding active site amino acids as a consequence of the amino acid changes. The encoded proteins expressed in Escherichia coli and purified by GSH affinity chromatography showed a 3-fold lower Km (CDNB) and a 3-4-fold higher Kcat/Km for the hGSTP1*A encoded protein than the proteins encoded by hGSTP1*B and hGSTP1*C. Analysis of 75 cases showed the relative frequency of hGSTP1*C to be 4-fold higher in malignant gliomas than in normal tissues. These data provide conclusive molecular evidence of allelopolymorphism of the human GST Pi gene locus, resulting in active, functionally different GST Pi proteins, and should facilitate studies of the role of this gene in xenobiotic metabolism, cancer, and other human diseases.

Authors
Ali-Osman, F; Akande, O; Antoun, G; Mao, JX; Buolamwini, J
MLA Citation
Ali-Osman, F, Akande, O, Antoun, G, Mao, JX, and Buolamwini, J. "Molecular cloning, characterization, and expression in Escherichia coli of full-length cDNAs of three human glutathione S-transferase Pi gene variants. Evidence for differential catalytic activity of the encoded proteins." J Biol Chem 272.15 (April 11, 1997): 10004-10012.
PMID
9092542
Source
pubmed
Published In
The Journal of biological chemistry
Volume
272
Issue
15
Publish Date
1997
Start Page
10004
End Page
10012

Detection of DNA damage in transcriptionally active genes by RT-PCR and assessment of repair of cisplatin-induced damage in the glutathione S-transferase-pi gene in human glioblastoma cells.

Cisplatin is an anticancer agent frequently used as an alternative to the nitrosoureas in brain tumor chemotherapy. We describe the use of a technique of quantitative reverse transcription-polymerase chain reaction (RT-PCR) to examine the damage induced in the glutathione S-transferase (GST)-pi gene by cisplatin and the subsequent repair of this damage in cells of the MGR3 human glioblastoma multiforme cell line. The relationship between cisplatin dose and the extent of damage in the GST-pi gene was determined over cisplatin concentrations (0-10 microM) within the clinically achievable range. Total RNA was purified from control and cisplatin-treated cells, and both the full-length GST-pi cDNA and control 200-bp beta-actin cDNA were amplified by RT-PCR. The cDNA reaction products were electrophoresed, Southern hybridized, and quantitated densitometrically. A decrease in GST-pi mRNA representing damage to the GST-pi gene was observed with increasing cisplatin concentrations, up to a maximum of 75% at 10 microM cisplatin. Repair of the GST-pi gene in cells treated with cisplatin, assessed as recovery of transcriptional activity of the gene, was shown to occur even after 48 hr following drug removal. A potent RNA polymerase II inhibitor, alpha-amanitin, was used to show that the GST-pi mRNA quantitated in this RT-PCR assay resulted from de novo RNA transcription of the GST-pi gene with little contribution from preexisting GST-pi transcripts. The results demonstrate that the GST pi gene, which is actively transcribed and often overexpressed in human glioma cells, is a target for cisplatin, but that the damage to the gene is efficiently repaired in these cells. The RT-PCR assay has the potential for use in the detection of DNA damage induced by genotoxic agents in other actively transcribed genes and for assessing the repair of gene-specific DNA lesions in cells.

Authors
Brandt, TY; Ali-Osman, F
MLA Citation
Brandt, TY, and Ali-Osman, F. "Detection of DNA damage in transcriptionally active genes by RT-PCR and assessment of repair of cisplatin-induced damage in the glutathione S-transferase-pi gene in human glioblastoma cells." Toxicol Appl Pharmacol 143.1 (March 1997): 22-29.
PMID
9073588
Source
pubmed
Published In
Toxicology and Applied Pharmacology
Volume
143
Issue
1
Publish Date
1997
Start Page
22
End Page
29
DOI
10.1006/taap.1996.8010

Characterization of the mechanisms of busulfan resistance in a human glioblastoma multiforme xenograft.

Busulfan is an alkylating agent commonly used in the treatment of chronic myelogenous leukemia and in combination with cyclophosphamide in preparation for allogeneic bone marrow transplantation. Serial treatment of a childhood high-grade glioma xenograft (D-456 MG) with busulfan resulted in a busulfan-resistant xenograft, D-456 MG(BR). Cross-resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea was seen but not resistance to cyclophosphamide or CPT-11. Cytoplasmic levels of glutathione in D-456 MG(BR) were approximately one-half those found in D-456 MG. This depletion could not be explained by levels of glutathione-S-transferase, or by amplification, rearrangement, or increased levels of transcript of gamma-glutamylcysteine synthetase. Furthermore, depletion of glutathione in D-456 MG did not alter busulfan activity. Quantitation of busulfan levels in D-456 MG and D-456 MG(BR) xenografts following treatment of mice at the dose lethal to 10% of the animals demonstrated that significantly lower levels of drug were achieved in D-456 MG(BR). These studies suggest that alterations in drug transport or metabolism of busulfan may play a role in the resistance of D-456 MG(BR) to this alkylator.

Authors
Hare, CB; Elion, GB; Colvin, OM; Ali-Osman, F; Griffith, OW; Petros, WP; Keir, S; Marcelli, SL; Bigner, DD; Friedman, HS
MLA Citation
Hare, CB, Elion, GB, Colvin, OM, Ali-Osman, F, Griffith, OW, Petros, WP, Keir, S, Marcelli, SL, Bigner, DD, and Friedman, HS. "Characterization of the mechanisms of busulfan resistance in a human glioblastoma multiforme xenograft." Cancer Chemother Pharmacol 40.5 (1997): 409-414.
PMID
9272117
Source
pubmed
Published In
Cancer Chemotherapy and Pharmacology
Volume
40
Issue
5
Publish Date
1997
Start Page
409
End Page
414
DOI
10.1007/s002800050678

Prognostic significance of glutathione S-transferase π expression and subcellular localization in human gliomas

The glutathione S-transferase (GST)-π gene is overexpressed in many human cancers and preneoplastic lesions and is associated with failure of cancer chemotherapy and poor patient survival. Although GST-π overexpression in tumors of the central nervous system has been observed, the prognostic and/or clinical relevance of this overexpression has, to date, not been investigated. In this study, we analyzed the level of GST-π expression and its subcellular localization in 61 primary gliomas and correlated the results with tumor histology, patient age, and patient survival. We observed a strong positive correlation between the level of GST-π expression and tumor grade and between the presence of GST-π in glioma cell nuclei and patient age. Univariate and multivariate Cox regression analyses and Kaplan-Meier curves showed the level of GST-π expression and its nuclear localization to be inversely correlated with patient survival. Relative risk for death of patients with high versus low tumor GST-π expression was 3.2 (P = 0.0069) by univariate analysis and 2.6 (P = 0.036) by multivariate analysis. The relative risk of death associated with the presence of nuclear GST-π in glioma cells was 3.9 (P = 0.0001) by univariate analysis and 4.4 (P < 0.0001) by multivariate analysis. These data indicate that high GST-π expression in tumor cells and the presence of the GST-π protein in tumor cell nuclei are associated with clinically more aggressive gliomas and are strong predictors of poor patient survival.

Authors
Ali-Osman, F; Brunner, JM; Kutluk, TM; Hess, K
MLA Citation
Ali-Osman, F, Brunner, JM, Kutluk, TM, and Hess, K. "Prognostic significance of glutathione S-transferase π expression and subcellular localization in human gliomas." Clinical Cancer Research 3.12 I (1997): 2253-2261.
Source
scival
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
3
Issue
12 I
Publish Date
1997
Start Page
2253
End Page
2261

Coordinate up-regulation of cyclin-dependent kinase 4 and its inhibitor p16(INK4) in human glioma cells following chloroethylnitrosourea-induced DNA damage

Anomalies in the genes of the cell cycle regulators, p16(INK4) and CDK4 are highly frequent in human gliomas and other cancers, however, the extent to which these defects are involved in regulating the response of tumor cells to DNA damaging agents is not clear. In this study, using three human malignant glioma cell lines, MGR1, MGR3, and U87MG, we examined changes in gene expression of p16 and/or of its specific target CDK4 following damage of the cellular genome by the chemotherapeutic bifunctional alkylating agent, 1,3-bis (2-chloroethyl)-l-nitrosourea (BCNU). Exposure of the cells to 50 μM BCNU for 24 h induced a significant level of DNA interstrand cross-links in all cell lines. In MGR1 cells (p16+, Rb+), over the 24 h period, a steady increase in p16 (mRNA and protein) and CDK4 (protein) was observed. The increase in CDK4 and p16 proteins occurred in parallel, and that the two proteins accumulated in complex with each other, resulting in marked inhibition of CDK4 kinase activity. In MGR3 and U87MG cells, both of which lack functional p16 protein (p16-, Rb+), BCNU, however increased the CDK4 protein levels. In all three cell lines, despite the differences in p16 gene status, BCNU exposure caused significant blockade of the cells at G2/M phase of the cell cycle. The coordinated enhancement of the target (CDK4) and the inhibitor (p16) in cellular response to genomic injury may reflect an attempt of the cells to continue progression through the cell cycle (via CDK4), while triggering the cell cycle arrest (via p16), required for the orderly repair of the damage to the genome.

Authors
Srivenugopal, KS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, and Ali-Osman, F. "Coordinate up-regulation of cyclin-dependent kinase 4 and its inhibitor p16(INK4) in human glioma cells following chloroethylnitrosourea-induced DNA damage." International Journal of Oncology 11.6 (1997): 1251-1256.
Source
scival
Published In
International Journal of Oncology
Volume
11
Issue
6
Publish Date
1997
Start Page
1251
End Page
1256

Molecular cloning, characterization, and expression in Escherichia coli of full-length cDNAs of three human glutathione S-transferase Pi gene variants. Evidence for differential catalytic activity of the encoded proteins

Authors
OSMAN, FA
MLA Citation
OSMAN, FA. "Molecular cloning, characterization, and expression in Escherichia coli of full-length cDNAs of three human glutathione S-transferase Pi gene variants. Evidence for differential catalytic activity of the encoded proteins." J. Biol. Chem. 272 (1997): 10004-10012.
Source
cinii-english
Published In
J. Biol. Chem.
Volume
272
Publish Date
1997
Start Page
10004
End Page
10012

Buthionine sulfoximine induction of gamma-L-glutamyl-L-cysteine synthetase gene expression, kinetics of glutathione depletion and resynthesis, and modulation of carmustine-induced DNA-DNA cross-linking and cytotoxicity in human glioma cells.

Glutathione (GSH) depletion by buthioninine sulfoximine (BSO) is being explored clinically as a means of enhancing the efficacy of cancer chemotherapy. We investigated the kinetics of GSH depletion and altered gamma-L-glutamyl-L-cysteine synthetase (gamma-GC-S) gene expression in two human malignant glioma cell lines, HBT5 and HBT28, and examined how these relate to GSH resynthesis and changes in DNA interstrand cross-link induction and cytotoxicity of 1,3-bis(2-chloroethyl)-nitrosourea (BCNU). GSH content was 54 and 126 nmol/mg/protein in HBT 5 and HBT 28, respectively, and after a 24-hr exposure to 100 microM BSO was decreased by 95% in HBT 5 and 91% in HBT 28. Basal gamma-GC-S enzyme activity in HBT 28 was twice that in HBT 5, and steady state gamma-GC-S gene transcripts were 2.6-fold higher in HBT 28 than in HBT 5, with no apparent amplification or rearrangement of the gene in either cell line. BSO exposure (100 microM) for 24 hr increased gamma-GC-S gene transcripts by 1.7-fold in HBT 5 and 2.8-fold in HBT 28. After BSO removal, the rate of GSH resynthesis in HBT 28 was twice that in HBT 5. Continuous BSO exposure increased the level of BCNU-induced DNA interstrand cross-links, and cytotoxicity was significantly higher in cells exposed continuously to BSO than in cells with only a 24-hr BSO preexposure. This increase was, however, greater in HBT 28 than in HBT 5. These findings indicate significant heterogeneity in the effects of BSO on gamma-GC-S gene expression and in the ability of BSO to sensitize tumors and cell lines to BCNU. The data also suggest that by preventing GSH resynthesis, a greater level of cytotoxicity is achieved with continuous BSO exposure than with BSO preexposure alone.

Authors
Ali-Osman, F; Antoun, G; Wang, H; Rajagopal, S; Gagucas, E
MLA Citation
Ali-Osman, F, Antoun, G, Wang, H, Rajagopal, S, and Gagucas, E. "Buthionine sulfoximine induction of gamma-L-glutamyl-L-cysteine synthetase gene expression, kinetics of glutathione depletion and resynthesis, and modulation of carmustine-induced DNA-DNA cross-linking and cytotoxicity in human glioma cells." Mol Pharmacol 49.6 (June 1996): 1012-1020.
PMID
8649339
Source
pubmed
Published In
Molecular pharmacology
Volume
49
Issue
6
Publish Date
1996
Start Page
1012
End Page
1020

Deletions and rearrangements inactivate the p16INK4 gene in human glioma cells.

Structural alterations in the p16INK4 gene were examined in early passage human glioma cell lines and related to the expression of p16 transcripts and protein. Using the Southern blot approach, we observed both homozygous and hemizygous deletions, as well as rearrangements of the p16 and p15 genes in 5 of the 7 cell lines (71%). Two cell lines, MGR3 and HBT28, revealed hemizygous deletion of the p16 and p15 genes combined with indistinguishable rearrangements of the remaining p15-p16 locus that resulted in loss of exon 2 sequences for p15 and p16, but retention of p16 exon 1; neither of these cell lines expressed p16 mRNA. Data for a third cell line, MGR2, indicated a similar, but unique rearrangement involving the p15 and p16 genes. MGR2, which retained a single wild-type p15-p16 locus, showed expression of p16 transcript, but not of p16 protein as indicated by Western blot analysis. All the glioma cell lines expressed similar levels of the retinoblastoma protein and no amplification of the cyclin-dependent kinase 4 gene. These results demonstrate that human glioma cells contain p16 gene microdeletions and rearrangements that contribute to inactivation of the cell cycle regulatory protein.

Authors
Srivenugopal, KS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, and Ali-Osman, F. "Deletions and rearrangements inactivate the p16INK4 gene in human glioma cells." Oncogene 12.9 (May 2, 1996): 2029-2034.
PMID
8649864
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
12
Issue
9
Publish Date
1996
Start Page
2029
End Page
2034

Ubiquitination-dependent proteolysis of O6-methylguanine-DNA methyltransferase in human and murine tumor cells following inactivation with O6-benzylguanine or 1,3-bis(2-chloroethyl)-1-nitrosourea.

In this study, we investigated the role of ubiquitination in the disposition of the inactivated O6-methylguanine-DNA methyltransferase (MGMT) protein in human (HT-29 and CEM) and murine (ts85) tumor cells. Using a combination of immunoprecipitation and immunoblotting techniques with antibodies against ubiquitin and MGMT, and anti-ubiquitin immunoaffinity chromatography, the MGMT protein was found to coexist with small amounts of its ubiquitinated species in both human and mouse tumor cells, suggesting the presence of endogenous inactivated MGMT. Further, treatment of HT-29 and CEM cells with MGMT-inactivating compounds, O6-benzylguanine (O6-BG, 20 microM) or 1,3-bis(chloroethyl)-1-nitrosourea (BCNU, 100 microM), resulted in increased levels of ubiquitinated MGMT within 1.5-3 h of drug exposure. Kinetic studies in HT-29 cells treated with O6-BG indicated a slow and gradual conversion of the inactivated MGMT to its polyubiquitinated forms over a course of 3-18 h, with a concomitant disappearance of the parent MGMT protein. We also characterized the previously reported O6-BG-induced degradation of MGMT in HT-29 cell extracts [Pegg et al. (1991) Carcinogenesis 12, 1679-1683] and showed the extracts to be active in conjugation of the MGMT protein with ubiquitin. The proteolysis of O6-BG-inactivated MGMT in HT-29 cell extracts was energy-dependent and was markedly stimulated by ATP and Mg2+ ions. Using the ts85 temperature-sensitive mutant cell line, which expresses a thermolabile ubiquitin-activating enzyme, we observed a differential stability of the inactivated MGMT protein at permissive and nonpermissive temperatures. These results provide conclusive evidence that the MGMT protein, following its inactivation, is degraded via the ubiquitin proteolytic pathway.

Authors
Srivenugopal, KS; Yuan, XH; Friedman, HS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, Yuan, XH, Friedman, HS, and Ali-Osman, F. "Ubiquitination-dependent proteolysis of O6-methylguanine-DNA methyltransferase in human and murine tumor cells following inactivation with O6-benzylguanine or 1,3-bis(2-chloroethyl)-1-nitrosourea." Biochemistry 35.4 (January 30, 1996): 1328-1334.
PMID
8573590
Source
pubmed
Published In
Biochemistry
Volume
35
Issue
4
Publish Date
1996
Start Page
1328
End Page
1334
DOI
10.1021/bi9518205

Repair analysis of 4-hydroperoxycyclophosphamide-induced DNA interstrand crosslinking in the c-myc gene in 4-hydroperoxycyclophosphamide-sensitive and -resistant medulloblastoma cell lines.

Cyclophosphamide is one of the most active agents in the treatment of medulloblastoma. However, development of resistance to this alkylator frequently occurs and is the harbinger of tumor progression and death. In order to understand the biochemical basis of this resistance, we generated a panel of medulloblastoma cell lines in our laboratory that were resistant to 4-hydroperoxycyclophosphamide (4-HC). Previously, we have shown that elevated levels of aldehyde dehydrogenase and glutathione mediate cellular resistance to 4-HC. The present study was conducted to identify the third unknown mechanism mediating the resistance of cell line D283 Med (4-HCR) to 4-HC, testing the hypothesis that this resistance is mediated by an increased repair of DNA interstrand crosslinks (ICLs). The doses of 4-HC that produced a one- and two-log cell kill of D283 Med cells were 25 and 50 microM, respectively, compared with values of 125 and 165 microM in D283 Med (4-HCR), the resistant cell line. The formation and disappearance of 4-HC-induced DNA ICLs at the c-myc gene were subsequently studied by DNA denaturing/renaturing gel electrophoresis and Southern blot analysis. 4-HC-induced DNA ICLs in the c-myc gene exhibited a dose-dependent relationship. The percentage of the c-myc gene that was crosslinked was approximately 1-3% at a dose of 100 microM. More than 50% of the DNA crosslinking in D283 Med (4-HCR) cells was removed by 6 h after drug treatment, whereas, in D283 Med cells, more than 90% of the DNA crosslinking was still present at 6 h. These findings suggest that the increased repair of DNA ICLs in D283 Med (4-HCR) may contribute significantly to its resistance to 4-HC.

Authors
Dong, Q; Bullock, N; Ali-Osman, F; Colvin, OM; Bigner, DD; Friedman, HS
MLA Citation
Dong, Q, Bullock, N, Ali-Osman, F, Colvin, OM, Bigner, DD, and Friedman, HS. "Repair analysis of 4-hydroperoxycyclophosphamide-induced DNA interstrand crosslinking in the c-myc gene in 4-hydroperoxycyclophosphamide-sensitive and -resistant medulloblastoma cell lines." Cancer Chemother Pharmacol 37.3 (1996): 242-246.
PMID
8529284
Source
pubmed
Published In
Cancer Chemotherapy and Pharmacology
Volume
37
Issue
3
Publish Date
1996
Start Page
242
End Page
246

Enhancement of melphalan activity by inhibition of DNA polymerase-alpha and DNA polymerase-beta.

Our previous studies exploring melphalan resistance in the human rhabdomyosarcoma xenograft TE-671 MR revealed elevation of DNA polymerase-alpha and DNA polymerase-beta. The present study evaluated the alteration of melphalan activity in TE-671 (melphalan-sensitive) and TE-671 MR (melphalan-resistant) subcutaneous xenografts in nude mice after DNA polymerase-alpha was inhibited using aphidicolin glycinate (AG) and DNA polymerase-beta was inhibited using dideoxycytidine (DDC). Administration of AG or DDC did not produce toxicity or demonstrate antineoplastic activity when given alone. AG (90 mg/m2) enhanced the activity of melphalan against TE-671, with growth delays increasing by 8.4, 15.8, and 21.2 days over the regimen with melphalan only. AG (180 mg/m2) only modestly increased melphalan activity against TE-671 MR, with the growth delays increasing from 9.6 and 12.1 days using melphalan alone to 12.1 and 14.5 days using melphalan plus AG. AG (180 mg/m2) plus melphalan (the dose lethal to 10% of animals) produced greater weight loss compared with melphalan alone, whereas DDC plus melphalan produced no additional toxicity. DDC modestly enhanced the activity of melphalan plus AG against TE-671 MR. AG plus O6-benzylguanine did not increase the activity of 1,3-bis(2-chloroethyl)-1-nitrosourea against TE-671 or TE-671 MR. AG (90 mg/m2 and 180 mg/m2) inhibited DNA polymerase-alpha to 80% and 72% of control in TE-671 and 64% and 37% in TE-671 MR, and DDC inhibited DNA polymerase-beta to 59% in TE-671 and 48% in TE-671 MR. These results suggest a role for AG-mediated enhancement of melphalan activity, particularly in the treatment of newly diagnosed, melphalan-sensitive tumors.

Authors
Moynihan, K; Elion, GB; Ali-Osman, F; Marcelli, S; Keir, S; Bigner, DD; Friedman, HS
MLA Citation
Moynihan, K, Elion, GB, Ali-Osman, F, Marcelli, S, Keir, S, Bigner, DD, and Friedman, HS. "Enhancement of melphalan activity by inhibition of DNA polymerase-alpha and DNA polymerase-beta." Cancer Chemother Pharmacol 38.4 (1996): 349-354.
PMID
8674158
Source
pubmed
Published In
Cancer Chemotherapy and Pharmacology
Volume
38
Issue
4
Publish Date
1996
Start Page
349
End Page
354

Culture of human normal brain and malignant brain tumors for cellular, molecular, and pharmacological studies.

Human brain neoplasms comprise a highly heterogeneous and biologically diverse group of tumors, the most common and most malignant of which are those of neuroepithelial origin (1) Despite intensive research, little is still understood about the cellular and molecular processes involved in the genesis, progression, and response to therapy of these tumors. Much of the progress made to date, however, has resulted, in part from advances in the ability to culture and propagate cells of both normal and neoplastic brain tissue in vitro (2, 3) For example, in vitro cultures have contributed significantly to the development of techniques, such as bromodeoxyuridine labeling, that are used to estimate the cell-growth kinetics of gliomas in patients (4) Normal brain and brain tumor cultures have also played a central role in research directed at a better understanding of the complex interplay between the cellular components of the brain, such as that between various glial cells, neurons, and endothelial cells (5, 6) In studies of the molecular and cellular mechanisms involved in brain tumor resistance to therapy, in vitro cultures of human glioma cells have played a significant role in the identification of O(6)-alkylguanine DNA alkyltransferase (7), glutathione, and glutathione S-transferases (8), as critical factors in human brain tumor alkylator resistance, findings that are providing the basis for novel therapies for human gliomas. Neurobiology and neurooncology research will therefore continue to be critically dependent on appropriate in vitro models of normal and neoplastic brain cells.

Authors
Ali-Osman, F
MLA Citation
Ali-Osman, F. "Culture of human normal brain and malignant brain tumors for cellular, molecular, and pharmacological studies." Methods Mol Med 2 (1996): 63-80.
PMID
21359734
Source
pubmed
Published In
Methods in Molecular Medicine
Volume
2
Publish Date
1996
Start Page
63
End Page
80
DOI
10.1385/0-89603-335-X:63

Simultaneous amplification of four DNA repair genes and beta-actin in human lymphocytes by multiplex reverse transcriptase-PCR.

We describe here the development, optimization, and use of a non-radioactive, quantitative, multiplex reverse transcriptase-PCR technique to measure, in a single reaction, the relative levels of the transcripts of four DNA repair genes (XPCC, hMSH2, XRCC1, and ERCC1) and the beta-actin gene in lymphoblastoid cell lines and frozen peripheral blood lymphocytes. Expression of defective DNA repair genes was not detected in DNA repair-deficient human cell lines, whereas the intact genes were detected in repair-proficient cell lines and in lymphocytes from a normal donor. The assay was reproducible, and repeated determinations of the same samples generated highly consistent results for each target gene. This approach should facilitate molecular epidemiological studies that incorporate screening for germline alterations that may affect gene expression and for changes in the levels of gene expression.

Authors
Wei, Q; Xu, X; Cheng, L; Legerski, RJ; Ali-Osman, F
MLA Citation
Wei, Q, Xu, X, Cheng, L, Legerski, RJ, and Ali-Osman, F. "Simultaneous amplification of four DNA repair genes and beta-actin in human lymphocytes by multiplex reverse transcriptase-PCR." Cancer research 55.21 (November 1995): 5025-5029.
PMID
7585546
Source
epmc
Published In
Cancer Research
Volume
55
Issue
21
Publish Date
1995
Start Page
5025
End Page
5029

Toxicity, biodistribution and radioprotective capacity of L-homocysteine thiolactone in CNS tissues and tumors in rodents: comparison with prior results with phosphorothioates.

L-Homocysteine thiolactone (L-HCTL) was evaluated for its potential as an intravenously-administered central nervous system (CNS) radioprotector in C3H mice and F344 rats. Toxicity assessments in the mouse yielded a LD50 of 297 mg/kg and in the rat 389 mg/kg. Biodistribution studies in tumor-bearing mice showed that brain specimens contained more label at 10 min than the tumors but less at 30 or 60 min. Brain uptake relative to the tumors, the brain/tumor ratio, ranged between 0.5 and 3.3. The cervical spinal cord of non-tumor-bearing rats was irradiated with 32 Gy 137Cs with or without prior treatment with L-HCTL following which the time to forelimb or hindlimb paralysis was measured to determine the relative protective factors (RPFs) for this radiation dose. For forelimb paralysis the RPF was 1.9 (+/- 1.0, SD) and for hindlimb it was 2.0 (+/- 1.1, SD). 36B-10 glioma cells irradiated in vitro with or without L-HCTL and assayed for colony forming capacity demonstrated a dose modifying factor (DMF) of only 1.15 (+/- 0.16, SE). Rats bearing intracerebral 36B-10 glioma received 137Cs irradiation with or without L-HCTL after which the tumors were similarly assayed in vitro. From this the glioma DMF was 1.2 (+/- 0.30, SE). Compared to prior results with phosphorothioates our data show that the toxicity of L-HCTL is roughly the same as WR2721, WR77913 and WR3689 and that it distributes at higher levels in the CNS after systemic administration. L-HCTL may well equal these phosphorothioates at protecting normal CNS tissue without requiring administration directly into the cerebrospinal fluid-containing spaces and it does not protect the 36B-10 glioma.

Authors
Spence, AM; Rasey, JS; Dwyer-Hansen, L; Grunbaum, Z; Livesey, J; Chin, L; Nelson, N; Stein, D; Krohn, KA; Ali-Osman, F
MLA Citation
Spence, AM, Rasey, JS, Dwyer-Hansen, L, Grunbaum, Z, Livesey, J, Chin, L, Nelson, N, Stein, D, Krohn, KA, and Ali-Osman, F. "Toxicity, biodistribution and radioprotective capacity of L-homocysteine thiolactone in CNS tissues and tumors in rodents: comparison with prior results with phosphorothioates." Radiother Oncol 35.3 (June 1995): 216-226.
PMID
7480825
Source
pubmed
Published In
Radiotherapy & Oncology
Volume
35
Issue
3
Publish Date
1995
Start Page
216
End Page
226

Identification of a brain- and reproductive-organs-specific gene responsive to DNA damage and retinoic acid.

We have identified and sequenced a new gene from human cells that is responsive to DNA damage and retinoic acid treatment, and it is highly expressed in brain and reproductive organs (BRE). This BRE gene encodes an mRNA of 1.7-1.9 kb, with an open reading frame of 1,149 bp, and gives rise to a deduced polypeptide of 383 amino acid residues. Treatment of fibroblast cell with UV and 4-nitroquinoline-1-oxide caused more than 90% and 50% decreases in BRE mRNA, respectively. Similar decreases in BRE expression were observed in RA-treatment of the brain glioma cell U-251 and the promyelocytic cell HL-60. Decrease in BRE mRNA was also observed in a squamous carcinoma cell, 1483, that showed X-ray resistance and has a more aggressive tumorigenic phenotype, but BRE expression was unchanged in cells after growth inhibition. These data indicate that BRE is a house-keeping gene and it may play a role in homeostatis or in certain pathways of differentiation in cells of neural, epithelial and germ line origins.

Authors
Li, L; Yoo, H; Becker, FF; Ali-Osman, F; Chan, JY
MLA Citation
Li, L, Yoo, H, Becker, FF, Ali-Osman, F, and Chan, JY. "Identification of a brain- and reproductive-organs-specific gene responsive to DNA damage and retinoic acid." Biochem Biophys Res Commun 206.2 (January 17, 1995): 764-774.
PMID
7826398
Source
pubmed
Published In
Biochemical and Biophysical Research Communications
Volume
206
Issue
2
Publish Date
1995
Start Page
764
End Page
774

Suppression of antiproliferative effects of tumor necrosis factor by transfection of cells with human platelet-derived growth factor B/c-sis gene.

The growth of cells is determined by the balance between growth-stimulatory and growth-inhibitory signals. In the present study, we demonstrate that the transfection of NIH 3T3 cells with a platelet-derived growth factor (PDGF-Blc-sis) gene induces resistance to the anticellular effects of tumor necrosis factor (TNF). Human tumor cell lines that express elevated levels of c-sis (e.g. epidermoid carcinoma, A-431) are also TNF resistant, whereas those that express no significant levels of this gene (e.g. breast adenocarcinoma, MCF-7) are TNF sensitive. Transfection of cells with the c-sis gene leads to down-modulation of TNF receptors and also a decrease in intracellular glutathione levels. Thus, our results demonstrate that over-expression of PDGF-Blc-sis by certain tumor cells can lead to their protection from the anticellular effects of TNF.

Authors
Aggarwal, BB; Pocsik, E; Totpal, K; Ali-Osman, F
MLA Citation
Aggarwal, BB, Pocsik, E, Totpal, K, and Ali-Osman, F. "Suppression of antiproliferative effects of tumor necrosis factor by transfection of cells with human platelet-derived growth factor B/c-sis gene." FEBS Lett 357.1 (January 2, 1995): 1-6.
PMID
8001667
Source
pubmed
Published In
FEBS Letters
Volume
357
Issue
1
Publish Date
1995
Start Page
1
End Page
6

Formation and repair of 1,3-bis-(2-chloroethyl)-1-nitrosourea and cisplatin induced total genomic DNA interstrand crosslinks in human glioma cells.

The kinetics of formation and repair of total genomic DNA interstrand crosslinks (ISCs) induced by BCNU and cis-DDP were studied in cells of 6 human malignant gliomas and related with their degree of drug resistance. DNA ISCs were formed rapidly (peak 6-12 h) following a 2 h exposure to 50 microM BCNU or 25 uM cis-DDP, and on an equimolar basis higher levels of crosslinking were observed with cis-DDP than with BCNU. Repair of cis-DDP induced crosslinks was characteristically bi-phasic and the rate was significantly higher than that for BCNU induced crosslinks. Overall, a low crosslink index and a high crosslink repair rate correlated with cis-DDP and BCNU resistance. The data demonstrate, conclusively, the ability of human glioma cells to repair cis-DDP and, for the first time, BCNU induced DNA ISCs and that DNA crosslink repair is a significant contributing factor to the resistance of these tumors to the two agents.

Authors
Ali-Osman, F; Rairkar, A; Young, P
MLA Citation
Ali-Osman, F, Rairkar, A, and Young, P. "Formation and repair of 1,3-bis-(2-chloroethyl)-1-nitrosourea and cisplatin induced total genomic DNA interstrand crosslinks in human glioma cells." Cancer Biochem Biophys 14.4 (January 1995): 231-241.
PMID
7767897
Source
pubmed
Published In
Cancer biochemistry biophysics
Volume
14
Issue
4
Publish Date
1995
Start Page
231
End Page
241

Transfection of cells with transforming growth factor-alpha leads to cellular resistance to the antiproliferative effects of tumor necrosis factor.

Tumor necrosis factor (TNF) is a growth-modulatory cytokine that inhibits the growth of certain cell lines, stimulates the growth of some, and has no effect on the growth of still others. The molecular basis for this differential regulation of growth by TNF is not understood. We postulate that the growth of normal or tumor cells is determined by the balance between growth-stimulatory and -inhibitory signals. In the present study, we demonstrate that the transfection of cells with the transforming growth factor (TGF)-alpha gene induces resistance to TNF. Colon carcinoma cell lines that express elevated levels of TGF-alpha were also found to be resistant to this cytokine. Exogenous addition of the growth factor was also effective in decreasing the antiproliferative effects of TNF. Transfection of cells with the TGF-alpha gene led to downmodulation of TNF receptors but an increase in intracellular glutathione levels. Thus, these results support our hypothesis that expression of growth factors by certain tumor cells can lead to resistance to antiproliferative agents such as TNF.

Authors
Aggarwal, BB; Pocsik, E; Ali-Osman, F; Totpal, K
MLA Citation
Aggarwal, BB, Pocsik, E, Ali-Osman, F, and Totpal, K. "Transfection of cells with transforming growth factor-alpha leads to cellular resistance to the antiproliferative effects of tumor necrosis factor." FEBS Lett 354.1 (October 31, 1994): 12-16.
PMID
7957892
Source
pubmed
Published In
FEBS Letters
Volume
354
Issue
1
Publish Date
1994
Start Page
12
End Page
16

Mechanism of the anti-tumour effect of biochemotherapy in melanoma: preliminary results.

During the conduct of a biochemotherapy trial in which cisplatin, vinblastine and dacarbazine (CVD) were administered concurrently with interleukin-2 (IL-2) plus interferon-alpha 2a (IFN-alpha 2a) (biochemotherapy) in advanced melanoma, we performed a series of laboratory studies in an attempt to understand better the mechanism of anti-tumour effect of the regimen. We initially hypothesized that CVD enhanced the anti-tumour effect of the biotherapy. However, in the first 10 patients studied, of whom eight were responders, we observed no lymphokine-associated killer cell (LAK) and minimal natural killer (NK) cell activities. This prompted us to change our initial hypothesis. Based on the work of others which showed a marked synergism between IL-1 alpha and cisplatin, apparently mediated by H2O2 derived from tumour-infiltrating macrophages, we reasoned that the biotherapy could enhance the cytotoxicity of the CVD regimen. To evaluate macrophage function, we measured serum neopterin levels in eight responders and seven non-responders. An increase of six or more times above baseline levels was observed in seven out of eight responders but in only two of seven non-responders (P = 0.041). We also examined the level of DNA inter-strand cross-link in peripheral blood mononuclear cells in four responders and four responders, as a means to evaluate the DNA repair process. A DNA cross-link index > or = 0.75 was observed in all four responders but only in one non-responder (P = 0.14). Our preliminary results suggest that concurrent biochemotherapy may exert its predominant anti-tumour effect by direct cytotoxicity and that macrophages may be involved in this process.

Authors
Buzaid, AC; Grimm, EA; Ali-Osman, F; Ring, S; Eton, O; Papadopoulos, NE; Bedikian, A; Plager, C; Legha, SS; Benjamin, R
MLA Citation
Buzaid, AC, Grimm, EA, Ali-Osman, F, Ring, S, Eton, O, Papadopoulos, NE, Bedikian, A, Plager, C, Legha, SS, and Benjamin, R. "Mechanism of the anti-tumour effect of biochemotherapy in melanoma: preliminary results." Melanoma Res 4.5 (October 1994): 327-330.
PMID
7858418
Source
pubmed
Published In
Melanoma Research
Volume
4
Issue
5
Publish Date
1994
Start Page
327
End Page
330

Correlation of total and interstrand DNA adducts in tumor and kidney with antitumor efficacies and differential nephrotoxicities of cis-ammine/cyclohexylamine-dichloroplatinum(II) and cisplatin.

Mixed amine platinum complexes have been identified as a new class of antitumor agents with activity in some cisplatin-resistant tumor models. cis-Ammine/cyclohexylamine-dichloroplatinum(II) is one such analog that we have evaluated in vivo and found it to have antitumor activity that was comparable to that of cisplatin in a solid murine fibrosarcoma tumor model. In contrast to the nephrotoxicity observed with cisplatin, the analog was free from inducing this side-effect. Pharmacokinetics of the two compounds administered i.v. at equitoxic dose levels to tumor-bearing mice indicated similar decay kinetics of total platinum in plasma, kidney and the tumor. Furthermore, DNA-platinum adducts of the two agents were similar in the tumor. Total adduct levels in the kidney, on the other hand, were significantly greater (P < 0.5) by up to 4-fold for cisplatin compared with the mixed amine analog. Likewise, the levels of interstrand cross-links of the two platinum complexes were comparable in the tumor, but significantly greater (P < 0.05) in the kidney for cisplatin. The data indicate that the greater renal levels of total and interstrand DNA-platinum adducts formed by cisplatin correlate with renal damage associated with this agent, and suggest that adduct levels, and not total tissue platinum levels, provide a more useful correlation with pharmacodynamic observations.

Authors
Yoshida, M; Khokhar, AR; Kido, Y; Ali-Osman, F; Siddik, ZH
MLA Citation
Yoshida, M, Khokhar, AR, Kido, Y, Ali-Osman, F, and Siddik, ZH. "Correlation of total and interstrand DNA adducts in tumor and kidney with antitumor efficacies and differential nephrotoxicities of cis-ammine/cyclohexylamine-dichloroplatinum(II) and cisplatin." Biochem Pharmacol 48.4 (August 17, 1994): 793-799.
PMID
8080453
Source
pubmed
Published In
Biochemical Pharmacology
Volume
48
Issue
4
Publish Date
1994
Start Page
793
End Page
799

Elevated DNA polymerase alpha, DNA polymerase beta, and DNA topoisomerase II in a melphalan-resistant rhabdomyosarcoma xenograft that is cross-resistant to nitrosoureas and topotecan.

Previous investigations have revealed that the human TE-671 MR human rhabdomyosarcoma xenograft selected in vivo for melphalan resistance (M. C. Rosenberg, et al., Cancer Res., 49: 6917-6922, 1989) is cross-resistant to a wide variety of alkylating agents and to bleomycin, but is collaterally sensitive to etoposide. Although glutathione levels were noted to be elevated in TE-671 MR compared to the melphalan-sensitive parental TE-671 xenograft, treatment with buthionine sulfoximine to deplete glutathione levels did not fully restore melphalan sensitivity in the TE-671 MR xenograft. The present studies were undertaken to search for additional mechanisms of resistance in the TE-671 MR xenograft. Drug sensitivity testing performed at the dose of agents that was lethal to 10% of the animals revealed that the TE-671 MR xenograft maintained resistance to the bifunctional cross-linking agent 1,3-bis(2-chloroethyl)-1-nitrosourea and was cross-resistant to the topoisomerase I poison topotecan. Treatment with buthionine sulfoximine did not sensitize the TE-671 MR xenograft to 1,3-bis(2-chloroethyl)-1-nitrosourea. Further, even though O6-alkylguanine-DNA alkyltransferase levels were high in both the TE-671 and TE-671 MR xenografts, depletion of O6-alkylguanine-DNA alkyltransferase activity by treatment with O6-benzylguanine substantially sensitized the TE-671 xenografts but not the TE-671 MR xenografts, suggesting an additional mechanism of resistance. Measurement of additional enzyme activities that might be involved in DNA repair revealed significant elevations in DNA polymerase alpha (46 +/- 8 (SD) units/mg protein in TE-671, 69 +/- 6 units/mg protein in TE-671 MR, P < 0.05) and DNA polymerase beta (0.43 +/- 0.01 units/mg protein in TE-671, 0.78 +/- 0.12 units/mg protein in TE-671 MR, P < 0.05) but not DNA polymerase delta or total DNA ligase. Examination of topoisomerases by activity assays and Western blotting revealed a 2-fold increase in topoisomerase II and a 2-fold decrease in topoisomerase I in the TE-671 MR xenograft compared to the parental xenograft, apparently explaining the collateral sensitivity to etoposide and cross-resistance to topotecan. These results suggest that TE-671 MR xenografts contain multiple changes in activities of DNA repair-related proteins and other nuclear proteins that could contribute to alkylating agent resistance.

Authors
Friedman, HS; Dolan, ME; Kaufmann, SH; Colvin, OM; Griffith, OW; Moschel, RC; Schold, SC; Bigner, DD; Ali-Osman, F
MLA Citation
Friedman, HS, Dolan, ME, Kaufmann, SH, Colvin, OM, Griffith, OW, Moschel, RC, Schold, SC, Bigner, DD, and Ali-Osman, F. "Elevated DNA polymerase alpha, DNA polymerase beta, and DNA topoisomerase II in a melphalan-resistant rhabdomyosarcoma xenograft that is cross-resistant to nitrosoureas and topotecan." Cancer Res 54.13 (July 1, 1994): 3487-3493.
PMID
8012971
Source
pubmed
Published In
Cancer Research
Volume
54
Issue
13
Publish Date
1994
Start Page
3487
End Page
3493

pp60v-src kinase overexpression leads to cellular resistance to the antiproliferative effects of tumor necrosis factor.

While some tumor cells are sensitive to the antiproliferative effects of tumor necrosis factor (TNF), others are resistant. The molecular basis for cellular resistance to TNF is not completely understood. Previously we have shown that transfection of cells with an oncogene HER2/neu/erb B2, a receptor tyrosine kinase, leads to resistance to the anticellular effects of TNF [(1988) Proc. Natl. Acad. Sci. USA 85, 5102-5106]. In the present study, we demonstrate that the overexpression of another oncogenic tyrosine kinase, pp60v-src also induces resistance to TNF. In contrast to HER2, however, pp60v-src transfection of cells did not lead to down-modulation of TNF receptors but rather to decreased intracellular glutathione levels. The pp60v-src-induced cellular resistance to TNF could be abrogated by interferon-gamma. Thus, these results indicate that the resistance of certain tumors to TNF may also be due in part to the overexpression of pp60v-src oncogene.

Authors
Aggarwal, BB; Totpal, K; Ali-Osman, F; Budde, RJ; Pocsik, E
MLA Citation
Aggarwal, BB, Totpal, K, Ali-Osman, F, Budde, RJ, and Pocsik, E. "pp60v-src kinase overexpression leads to cellular resistance to the antiproliferative effects of tumor necrosis factor." FEBS Lett 345.2-3 (May 30, 1994): 219-224.
PMID
7911089
Source
pubmed
Published In
FEBS Letters
Volume
345
Issue
2-3
Publish Date
1994
Start Page
219
End Page
224

Cell density-dependent regulation of cell surface expression of two types of human tumor necrosis factor receptors and its effect on cellular response.

Tumor necrosis factor (TNF) is a multipotential cytokine known to regulate the growth of a wide variety of normal and tumor cells. It has been shown that the density of cells in culture can modulate the growth regulatory activities of TNF, the mechanism of which, however, is not understood. In this report, we investigated the effect of cell density on the expression of TNF receptors. The receptors were examined on epithelial cells (e.g., HeLa), which primarily express the p60 form, and on myeloid cells (e.g., HL-60) known to express mainly the p80 form. We observed that binding of TNF to both cell lines decreased with increase in cell density. Scatchard analysis of binding on HeLa and HL-60 cells revealed a 4- to 5-fold reduction in the number of TNF receptors without any significant change in receptor affinity in both cell types at high density. The decrease in TNF receptor numbers at high cell density was also observed in several other epithelial and myeloid cell lines. The downmodulation at high cell density was unique to TNF receptors, since minimum change in other cell surface proteins was observed as revealed by fluorescent activated cell sorter analysis. Neutralization of binding with antibodies specific to each type of the receptors revealed that both the p60 and p80 forms of the TNF receptor were equally downmodulated. A decrease in leucine incorporation into proteins was observed with increase in cell density, suggesting a reduction in protein synthesis. Since inhibition of protein synthesis by cycloheximide also leads to a decrease in TNF receptors, it is possible that the density-dependent reduction in TNF receptor number is due to an overall decrease in protein synthesis. The density-dependent decrease in TNF receptors was accompanied by a decrease in intracellular reduced glutathione levels. A reduction in the number of receptors on TNF sensitive tumor cells induced by cell-density correlated with increase in resistance to the cytokine.

Authors
Pocsik, E; Mihalik, R; Ali-Osman, F; Aggarwal, BB
MLA Citation
Pocsik, E, Mihalik, R, Ali-Osman, F, and Aggarwal, BB. "Cell density-dependent regulation of cell surface expression of two types of human tumor necrosis factor receptors and its effect on cellular response." J Cell Biochem 54.4 (April 1994): 453-464.
PMID
8014194
Source
pubmed
Published In
Journal of Cellular Biochemistry
Volume
54
Issue
4
Publish Date
1994
Start Page
453
End Page
464
DOI
10.1002/jcb.240540412

Induction of tissue-type plasminogen activator and 72-kDa type-IV collagenase by ionizing radiation in rat astrocytes.

Radiation-induced damage in the central nervous system (CNS) is believed to be targeted to glial or endothelial cells or both, although the pathophysiology of the process is still poorly understood. In this study, we irradiated rat astrocytes with single doses of X-rays and then estimated the levels of tissue plasminogen activator (tPA) and collagenase in serum-free medium and cell extracts at different times. Fibrin zymography revealed increased levels of intracellular tPA activity at 12 hr after irradiation. Gelatin zymography showed continuously increasing levels of extracellular 72-kDa type-IV collagenase after irradiation. Quantitative enzymatic activities by densitometry showed a 3- to 4-fold elevation in the level of the intracellular tPA activity at 12 hr and a 5- to 6-fold increase in the level of the extracellular 72-kDa type-IV collagenase activity at 48 hr. An ELISA with specific antibodies for tPA and 72-kDa type-IV collagenase indicated a 5-fold increase in the level of tPA at 12 hr and a more-than-7-fold increase in the level of 72-kDa type-IV collagenase at 48 hr. This study adds considerable credibility to the proposed role of plasminogen activators and type-IV collagenase in the development of CNS damage after radiotherapy for brain tumors.

Authors
Sawaya, R; Tofilon, PJ; Mohanam, S; Ali-Osman, F; Liotta, LA; Stetler-Stevenson, WG; Rao, JS
MLA Citation
Sawaya, R, Tofilon, PJ, Mohanam, S, Ali-Osman, F, Liotta, LA, Stetler-Stevenson, WG, and Rao, JS. "Induction of tissue-type plasminogen activator and 72-kDa type-IV collagenase by ionizing radiation in rat astrocytes." Int J Cancer 56.2 (January 15, 1994): 214-218.
PMID
8314304
Source
pubmed
Published In
International Journal of Cancer
Volume
56
Issue
2
Publish Date
1994
Start Page
214
End Page
218

Enhanced repair of a cisplatin-damaged reporter chloramphenicol-O-acetyltransferase gene and altered activities of DNA polymerases alpha and beta, and DNA ligase in cells of a human malignant glioma following in vivo cisplatin therapy.

Current evidence suggest an important role for increased repair of drug-induced DNA damage as one of the major mechanisms involved in tumor cell resistance to cis-DDP. In this study, we examined the DNA repair capacity and the activities of three DNA repair related proteins, namely, DNA polymerases alpha and beta, and total DNA ligase in cells of a malignant oligodendroglioma obtained from a patient before therapy and compared it with those of a specimen of the tumor acquired after the patient had failed cis-DDP therapy. DNA repair capacity was quantitated as the extent of reactivation of the chloramphenicol-O-acetyltransferase (CAT) gene in a eukaryotic expression vector that had been damaged and inactivated by prior treatment with cis-DDP and then transfected into the tumor cells. The extent of DNA-platinum adduct formation in the expression vector was determined by flameless atomic absorption spectrometry. The level of cis-DDP resistance of cells of the two tumors was determined with the capillary tumor stem cell assay. We observed a 2.8-fold increased capacity to repair Pt-DNA adducts and reactivate the CAT gene in cells of the tumor obtained after cis-DDP therapy, compared to cells of the untreated tumor. This was associated with increases of 9.4-fold and a 2.3-fold, respectively, in DNA polymerase beta and total DNA ligase activities in cells of the treated tumor. At 5 microM cis-DDP, there was a 5.9-fold increase in the in vitro cis-DDP resistance of post-therapy tumor cells relative to cells of the untreated tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

Authors
Ali-Osman, F; Berger, MS; Rairkar, A; Stein, DE
MLA Citation
Ali-Osman, F, Berger, MS, Rairkar, A, and Stein, DE. "Enhanced repair of a cisplatin-damaged reporter chloramphenicol-O-acetyltransferase gene and altered activities of DNA polymerases alpha and beta, and DNA ligase in cells of a human malignant glioma following in vivo cisplatin therapy." J Cell Biochem 54.1 (January 1994): 11-19.
PMID
8126081
Source
pubmed
Published In
Journal of Cellular Biochemistry
Volume
54
Issue
1
Publish Date
1994
Start Page
11
End Page
19
DOI
10.1002/jcb.240540103

Role of plasminogen activator and of 92-KDa type IV collagenase in glioblastoma invasion using an in vitro matrigel model.

The invasive nature of human gliomas represents a major factor in preventing their total resection. The exact nature of the underlying mechanisms of tumor cell invasion are still unclear. In this study, we have quantitatively assayed a glioblastoma cell line for its ability to migrate through a polycarbonate filter coated with matrigel which contains a complex of multiple basement membrane components. At 48 h the glioblastoma cell line (U251) showed a rate of invasiveness of 42% and also dependent on the concentration of matrigel. The U251 cell line produced a urokinase type plasminogen activator and a 92-KDa type IV collagenase. Both enzymes were inhibited by the addition of uPA and 92-KDa type IV collagenase antibodies. Those same antibodies reduced the invasion rate of U251 cells from 42% to 12 and 21%, respectively. Similarly, the addition of epsilon-aminocaproic acid (a plasmin inhibitor) or tissue inhibitor of metalloprotease (TIMP2, a collagenase inhibitor) reduced the invasiveness of U251 cells from 42% to 14% and 10%, respectively. Additionally, the other two glioblastoma cell lines (LG11, UWR1) and astrocytes showed a rate of invasiveness at 41%, 61% and 12%, respectively. Finally, the addition of hyaluronic acid to the matrigel, a constituent of brain extracellular matrix, enhanced the rate of invasion. These findings provide evidence for the role of serine proteases and metalloproteases in facilitating the invasion of extracellular matrix components by glioblastoma cell line and suggest a therapeutic role for protease inhibitors in attempting to minimize the invasive propensity of gliomas.

Authors
Rao, JS; Steck, PA; Tofilon, P; Boyd, D; Ali-Osman, F; Stetler-Stevenson, WG; Liotta, LA; Sawaya, R
MLA Citation
Rao, JS, Steck, PA, Tofilon, P, Boyd, D, Ali-Osman, F, Stetler-Stevenson, WG, Liotta, LA, and Sawaya, R. "Role of plasminogen activator and of 92-KDa type IV collagenase in glioblastoma invasion using an in vitro matrigel model." J Neurooncol 18.2 (1994): 129-138. (Review)
PMID
7964975
Source
pubmed
Published In
Journal of Neuro-Oncology
Volume
18
Issue
2
Publish Date
1994
Start Page
129
End Page
138

Topoisomerase II inhibition and altered kinetics of formation and repair of nitrosourea and cisplatin-induced DNA interstrand cross-links and cytotoxicity in human glioblastoma cells.

By altering the accessibility of DNA sequences for alkylation or platination, and/or for subsequent repair, topoisomerase II can potentially affect the level of DNA interstrand cross-links induced in cells by bifunctional agents. In this study, we investigated the extent to which inhibition of topoisomerase II activity in a human glioblastoma multiforme cell line alters the kinetics of both the formation and the repair of total genomic DNA interstrand cross-links, as well as the sensitivity of the tumor cells to cis-diamminedichloroplatinum II (cis-DDP) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Cells were incubated with and without 200 microM novobiocin, a known topoisomerase II inhibitor, for 24 h, followed by exposure to 50 microM BCNU and 25 microM cis-DDP. DNA interstrand cross-linking was determined at various time points over 72 h, using a modified ethidium bromide-DNA binding assay. Sensitivity of the cells to cis-DDP and BCNU was also determined with and without novobiocin pretreatment with 200 microM novobiocin. This concentration of novobiocin showed no significant direct cytotoxicity, although it inhibited topoisomerase II activity in tumor cell nuclear extracts by 73%. A significant decrease in the rate of repair of both cis-DDP and BCNU induced DNA interstrand cross-links, with a corresponding decrease in the clonogenic survival of the cells, was observed following novobiocin exposure. Although the peak cross-link indices of novobiocin-treated cells relative to controls were not significantly increased, residual DNA cross-linking in the cells after 72 h was increased by 1.4-fold for BCNU and 3-fold for cells treated with cis-DDP, thus, indicating a greater effect of topoisomerase II on cross-link repair than on cross-link formation. These data suggest that inhibition of topoisomerase II may provide a potentially effective clinical strategy for sensitizing human brain tumors, and possibly other tumors as well, to DNA cross-linking anticancer agents.

Authors
Ali-Osman, F; Berger, MS; Rajagopal, S; Spence, A; Livingston, RB
MLA Citation
Ali-Osman, F, Berger, MS, Rajagopal, S, Spence, A, and Livingston, RB. "Topoisomerase II inhibition and altered kinetics of formation and repair of nitrosourea and cisplatin-induced DNA interstrand cross-links and cytotoxicity in human glioblastoma cells." Cancer Res 53.23 (December 1, 1993): 5663-5668.
PMID
8242621
Source
pubmed
Published In
Cancer Research
Volume
53
Issue
23
Publish Date
1993
Start Page
5663
End Page
5668

Glutathione-associated cis-diamminedichloroplatinum(II) metabolism and ATP-dependent efflux from leukemia cells. Molecular characterization of glutathione-platinum complex and its biological significance.

Accumulating evidence suggests a critical role of intracellular glutathione in tumor cell resistance to alkylating agents. The present study provides evidence for the direct interaction between cis-diamminedichloroplatinum(II) (cisplatin) and glutathione (GSH) both in a cell-free system, as well as in L1210 murine leukemia cells. We have isolated the reaction product and identified it by a combination of high performance liquid chromatography and atomic absorption spectroscopy. Stoichiometric analysis showed a 2:1 molar ratio of GSH/cisplatin for the reaction. The molecular mass assessed by mass spectroscopy was 809 Da, corresponding to a GS-platinum chelate complex, bis-(glutathionato)-platinum. The GS-platinum complex was detected in L1210 leukemia cells incubated with 20 microM cisplatin. The intracellular content of the GS-platinum complex reached a maximal level after 12 h, corresponding to about 60% of the intracellular platinum content. Thus, formation of the GS-platinum complex is considered a significant part of the cellular metabolism of cisplatin. The GS-platinum was found to inhibit cell-free protein synthesis in a rabbit reticulocyte lysate system using both chloramphenicol acetyltransferase mRNA and poly(A) mRNA from HL-60 human promyelocytic leukemia cells (IC50 = 190 microM the GS-platinum complex). Elimination of the GS-platinum complex from tumor cells may represent an important mechanism which reduces the intracellular accumulation of the platinum complex. Using plasma membrane vesicles prepared from L1210 cells, the transport of the GS-platinum complex across the plasma membrane was found to be an ATP-dependent process (apparent Km values: 49 microM, ATP; 110 microM, GS-platinum complex). The ATP-dependent transport of the GS-platinum complex was inhibited by vanadate (IC50 = 35 microM) as well as by S-(2,4-dinitrophenyl)-glutathione, leukotriene C4, and GSSG, but not by doxorubicin, daunorubicin, or verapamil. The ATP-dependent glutathione S-conjugate export pump, "GS-X pump" (Ishikawa, T. (1992) Trends Biochem. Sci. 17, 463-468), is suggested to play a role in the elimination of the GS-platinum complex from tumor cells.

Authors
Ishikawa, T; Ali-Osman, F
MLA Citation
Ishikawa, T, and Ali-Osman, F. "Glutathione-associated cis-diamminedichloroplatinum(II) metabolism and ATP-dependent efflux from leukemia cells. Molecular characterization of glutathione-platinum complex and its biological significance." J Biol Chem 268.27 (September 25, 1993): 20116-20125.
PMID
8376370
Source
pubmed
Published In
The Journal of biological chemistry
Volume
268
Issue
27
Publish Date
1993
Start Page
20116
End Page
20125

Modulation of in vitro invasion of human glioblastoma cells by urokinase-type plasminogen activator receptor antibody.

Four human glioblastoma cell lines (U251, UWR1, UWR2, and UWR3) were tested for the expression of the cell surface receptor for urokinase-type plasminogen activator (uPA). To our knowledge there have been no previous reports about the uPA receptors (uPARs) in glioblastoma cell lines. All four glioblastoma cell lines we tested were found to bind recombinant Pro-uPA saturably and reversibly. Scatchard analysis of radioligand binding with acid-pretreated cells showed the presence of a single population of high-affinity uPARs on glioblastoma cells. Northern blot analysis confirmed that glioblastoma cells like other human cell lines express a 1.4-kilobase uPAR mRNA and 2.4-kilobase uPA mRNA. The significance of the uPAR in the invasive potential of the cells was examined by incubating uPAR antibody in an in vitro invasion assay. The anti-uPAR monoclonal antibody blocked the invasion effectively in a Matrigel assay, in which inhibition of invasion ranged between 20 and 57% for the cells studied. These data suggest that the uPARs contribute significantly to the invasive capacity of the cells, possibly by facilitating uPA activity.

Authors
Mohanam, S; Sawaya, R; McCutcheon, I; Ali-Osman, F; Boyd, D; Rao, JS
MLA Citation
Mohanam, S, Sawaya, R, McCutcheon, I, Ali-Osman, F, Boyd, D, and Rao, JS. "Modulation of in vitro invasion of human glioblastoma cells by urokinase-type plasminogen activator receptor antibody." Cancer Res 53.18 (September 15, 1993): 4143-4147.
PMID
8395977
Source
pubmed
Published In
Cancer Research
Volume
53
Issue
18
Publish Date
1993
Start Page
4143
End Page
4147

Purification and biochemical characterization of gamma-glutamylcysteine synthetase from a human malignant astrocytoma cell line.

gamma-Glutamylcysteine synthetase (EC 6.3.2.2.) the key regulatory enzyme in glutathione biosynthesis was purified from a human malignant astrocytoma cell line using a combination of ammonium sulfate fractionation, DE-52 cellulose chromatography and ATP-agarose affinity chromatography. The purified protein had a specific activity of 1725 units/mg protein, which represented an 86-fold purification and a 22% yield. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two major subunits with apparent molecular sizes of 72 kDa and 32 kDa. The Km values for L-glutamate and L-alpha-aminobutyrate were 0.03 mM and 0.14 mM respectively. These molecular and catalytic properties of gamma-glutamylcysteine synthetase from astrocytoma cell line are similar, but not identical to those purified from rat kidney.

Authors
Sriram, R; Ali-Osman, F
MLA Citation
Sriram, R, and Ali-Osman, F. "Purification and biochemical characterization of gamma-glutamylcysteine synthetase from a human malignant astrocytoma cell line." Biochem Mol Biol Int 30.6 (August 1993): 1053-1060.
PMID
8106072
Source
pubmed
Published In
IUBMB Life
Volume
30
Issue
6
Publish Date
1993
Start Page
1053
End Page
1060

Pituitary oncocytomas: clinical features, characteristics in cell culture, and treatment recommendations.

To determine whether there are significant differences between oncocytomas and pituitary adenomas, we evaluated clinical features, treatment regimens and outcome in 23 males and 9 females (average age 64 years, range 43-81 years) with the histologic diagnosis of pure pituitary oncocytomas (> 95% oncocytes). Symptom duration was six to twelve months in 6 cases (19%) and more than one year in 19 cases (59%). Three patients presented with sudden onset of symptoms, and were found to have hemorrhage within their tumors. Visual loss (69%) and symptoms of hypopituitarism (44%) were the most common presenting complaints. Preoperative endocrine profiles revealed abnormalities in most cases, including pituitary insufficiency in 56% and hyperprolactinemia in 59%. The tumors were typically large at presentation; all but one had suprasellar extension. 28 patients underwent transsphenoidal tumor resections; 4 underwent subfrontal craniotomies. Gross dural invasion was found at surgery in 11 cases. At a mean followup of 31 months (range 2-68 months), recurrent tumor was identified in 4 patients (12.5%). Tumor size, dural invasion, preoperative endocrine profile, and postoperative radiotherapy did not correlate with recurrence. Among seven oncocytomas grown in culture, five demonstrated two distinct cell types consisting of oncocytes and typical adenoma cells, respectively. Oncocytomas often have a different clinical presentation than functional pituitary adenomas.

Authors
Silbergeld, DL; Mayberg, MR; Berger, MS; Ali-Osman, F; Kelly, WA; Shaw, CM
MLA Citation
Silbergeld, DL, Mayberg, MR, Berger, MS, Ali-Osman, F, Kelly, WA, and Shaw, CM. "Pituitary oncocytomas: clinical features, characteristics in cell culture, and treatment recommendations." J Neurooncol 16.1 (April 1993): 39-46.
PMID
8410141
Source
pubmed
Published In
Journal of Neuro-Oncology
Volume
16
Issue
1
Publish Date
1993
Start Page
39
End Page
46

Development of lipophilic anticancer agents for the treatment of brain tumors by the esterification of water-soluble chlorambucil.

The lipophilic derivatives of the anticancer alkylating agent chlorambucil, chlorambucil-methyl, -isopropyl and -tertiary butyl esters, were synthesized and administered i.v. to anesthetized rats. Plasma and brain concentrations of these agents and of their active metabolites, chlorambucil and phenylacetic mustard, then were determined by high-performance liquid chromatography between 5 and 60 min. Whereas large amounts of chlorambucil-tertiary butyl ester entered and were maintained in brain, lower amounts of chlorambucil-isopropyl ester and no chlorambucil-methyl ester were found in brain. The comparative brain/plasma concentration-time integral ratios of the total active agents generated from chlorambucil-tertiary butyl, -isopropyl and -methyl esters were 0.85, 0.12 and 0.06, respectively, compared to a ratio of 0.02 for chlorambucil. In vitro alkylating activity of each ester was compared to that of equimolar chlorambucil, by reaction with 4-(p-nitrobenzyl)pyridine. Each ester possessed high intrinsic alkylating activity, equal to 38.4, 57.0 and 69.9% of chlorambucil activity, for the -tertiary butyl, -isopropyl and -methyl esters, respectively. Therefore each is an active antineoplastic agent irrespective of whether or not chlorambucil is regenerated. The rates of ester hydrolysis of these derivatives to chlorambucil were measured in fresh rat blood and in liver and brain homogenates at 37 degrees C. Chlorambucil-methyl and -isopropyl esters were hydrolysed quickly within 30 s in blood and liver, whereas chlorambucil-tertiary butyl ester was more stable with half-lives of approximately 7 h and 2 h, respectively. All proved to be relatively stable in brain homogenate. Steric hindrance around the ester linkage of chlorambucil-tertiary butyl ester reduces its affinity to and rate of hydrolysis by plasma and liver esterases, and allows it to accumulate within the brain. Chlorambucil-tertiary butyl ester maintains high levels in brain despite rapidly declining plasma concentrations and, due to these favorable pharmacokinetics and to its intrinsic anticancer activity, it possess promising characteristics for the treatment of malignant brain tumors.

Authors
Genka, S; Deutsch, J; Shetty, UH; Stahle, PL; John, V; Lieberburg, IM; Ali-Osman, F; Rapoport, SI; Greig, NH
MLA Citation
Genka, S, Deutsch, J, Shetty, UH, Stahle, PL, John, V, Lieberburg, IM, Ali-Osman, F, Rapoport, SI, and Greig, NH. "Development of lipophilic anticancer agents for the treatment of brain tumors by the esterification of water-soluble chlorambucil." Clin Exp Metastasis 11.2 (March 1993): 131-140.
PMID
8444006
Source
pubmed
Published In
Clinical & Experimental Metastasis
Volume
11
Issue
2
Publish Date
1993
Start Page
131
End Page
140

Phase II evaluation of high-dose intravenous cisplatin for treatment of adult malignant gliomas recurrent after chloroethylnitrosourea failure.

Twenty-one patients with recurrent malignant glioma who had failed prior chemotherapy with nitrosoureas were treated with high-dose intravenous cisplatin on days 1 and 8 of successive 4 week cycles. Fourteen patients were evaluable for response. Four patients showed partial responses; mean time to tumor progression (MTP) was 8 weeks. Six patients stabilized; MTP was 11 weeks. Four patients showed no response. There were no infectious or hemorrhagic complications, but partial hearing loss occurred in 7 patients and severe vomiting in 8 patients. High-dose intravenous cisplatin demonstrates substantial activity against malignant gliomas recurrent after chloroethylnitrosourea (CENU) failure.

Authors
Spence, AM; Berger, MS; Livingston, RB; Ali-Osman, F; Griffin, B
MLA Citation
Spence, AM, Berger, MS, Livingston, RB, Ali-Osman, F, and Griffin, B. "Phase II evaluation of high-dose intravenous cisplatin for treatment of adult malignant gliomas recurrent after chloroethylnitrosourea failure." J Neurooncol 12.2 (February 1992): 187-191.
PMID
1560266
Source
pubmed
Published In
Journal of Neuro-Oncology
Volume
12
Issue
2
Publish Date
1992
Start Page
187
End Page
191

Induction of transformational changes in normal endothelial cells by cultured human astrocytoma cells.

Endothelial cell proliferation is a significant biological feature of malignant astrocytomas. The ability of the cells of these tumors to elaborate mitogenic angiogenesis factors has been well documented. However, less is known about the transformational effects that neoplastic astrocytes may have on the endothelial cells within malignant astrocytomas. In this study, the hypothesis that humoral factors elaborated by cells derived from malignant astrocytomas induce transformational changes in normal endothelial cells in vitro is investigated. Conditioned medium (CM) was prepared from exponentially growing cultures of a human glioblastoma cell line (UW18) and from two rat brain-tumor cell lines: an anaplastic astrocytoma (R175A) and a glioblastoma with sarcomatous elements (9L). Subconfluent target bovine aortic arch endothelial cells (BAEC's) were exposed for 48 hours to varying concentrations of CM prepared from each of these tumors, and then evaluated for transformational changes. Different molecular weight (MW) fractions of UW18 CM were prepared by molecular ultrafiltration, and each fraction was tested for transforming activity. Transformation endpoints included changes in cellular deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) content and distribution (measured by differential flow cytometry) and changes in de novo DNA synthesis determined by 3H-thymidine incorporation. Significant changes in the amount and distribution of DNA and RNA were observed in the BAEC's treated with UW18 CM compared to untreated BAEC's. At 10% concentrations of UW18 CM, changes in the RNA profile of target BAEC's were evident, and at 30% concentrations of UW18 CM, an irregular bimodal distribution was well established. Patterns of DNA were also altered in a concentration-dependent manner, with significant aneuploidy developing at UW18 CM concentrations of 20%. The DNA synthesis in BAEC's increased with increasing CM concentrations, up to a maximum of about 250% of control values at 30% concentrations of UW18 CM. The transformational changes induced after exposure of BAEC's to CM prepared from R175A and 9L were significantly less than those observed with UW18 CM. Molecular ultrafiltration was used to prepare UW18 CM fractions with MW cutoffs of less than 10 kD, 10 to 30 kD, and greater than 30 kD. Transformational activity was significant only in CM's with an MW of 10 to 30 kD. It is concluded that the UW18 human glioblastoma cell line elaborates a soluble factor, or group of factors, with an MW in the 10- to 30-kD range, capable of inducing transformational alterations in target normal endothelial cells, and that such transformation may account for some of the abnormal endothelial cell changes associated with malignant astrocytomas.

Authors
Silbergeld, DL; Ali-Osman, F; Winn, HR
MLA Citation
Silbergeld, DL, Ali-Osman, F, and Winn, HR. "Induction of transformational changes in normal endothelial cells by cultured human astrocytoma cells." J Neurosurg 75.4 (October 1991): 604-612.
PMID
1885978
Source
pubmed
Published In
Journal of neurosurgery
Volume
75
Issue
4
Publish Date
1991
Start Page
604
End Page
612
DOI
10.3171/jns.1991.75.4.0604

Isolation and characterization of microvessels from normal brain and brain tumors.

We describe a new technique for isolating microvessels from both brain and brain tumors. This method is relatively quick and provides a microvessel preparation free of contamination by other brain tissue. Using this method, structurally intact microvessels from normal rat brain and from a malignant rat astrocytoma were isolated and characterized with light microscopy, scanning electron microscopy and transmission electron microscopy. In contrast to microvessels derived from normal rat brain, rat astrocytoma microvessels had endothelial cells with multilayered basement membranes, extensive microvilli on the cell surfaces, and a significant increase in the number of pinocytes in the cytoplasm. Furthermore, astrocytoma microvessel endothelial cells had pleomorphic electron dense nuclei with pale perichromatin, whereas the nuclei of endothelial cells of microvessels derived from normal brain tissue were finely granular and homogeneous with characteristically electron dense perichromatin. The morphologic characteristics of the astrocytoma microvessels are similar to the histologic changes seen in astrocytoma tissue in situ, and correlate well with the known altered functions of brain tumor neovasculature.

Authors
Silbergeld, DL; Ali-Osman, F
MLA Citation
Silbergeld, DL, and Ali-Osman, F. "Isolation and characterization of microvessels from normal brain and brain tumors." J Neurooncol 11.1 (August 1991): 49-55.
PMID
1919646
Source
pubmed
Published In
Journal of Neuro-Oncology
Volume
11
Issue
1
Publish Date
1991
Start Page
49
End Page
55

Glutathione content and glutathione-S-transferase expression in 1,3-bis(2-chloroethyl)-1-nitrosourea-resistant human malignant astrocytoma cell lines.

gamma-L-glutamyl-L-cysteinylglycine (GSH) has been shown to inactivate 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and quench DNA crosslink precursors of BCNU. Because of the central role of 2-chloroethyl-nitrosoureas in brain tumor chemotherapy, we investigated the intracellular GSH content and the expression of specific glutathione-S-transferases (GSTs) in three human malignant astrocytoma cell lines (UWR1, UWR2, and UWR3) of varying BCNU resistance to determine the interrelationship of these parameters with brain tumor BCNU resistance. GSH was assayed by ion-exchange high performance liquid chromatography after derivatization with 1-fluoro-2,4 dinitrobenzene. Both bulk and specific GST (acid, near-neutral, and basic) activities were examined using substrates that show high specificities to the different GSTs. Western blot analyses with antisera against GST-alpha, -mu, and -tau subunits were also performed on partially purified GST from the cells of each cell line. The results showed GSH content of 91, 46.5, and 28.3 nmol GSH/mg protein for UWR1, UWR2, and UWR3, respectively. Bulk GST activity (with 1-chloro-2,4-dinitrobenzene as substrate) also correlated with increasing BCNU resistance. Of the three GST classes examined by both substrate specificities and Western blotting, only the expression of the acidic form, GST-tau, correlated significantly with the rank order of BCNU resistance of the cell lines. GST-mu and -alpha were present in only trace amounts in all three cell lines.

Authors
Ali-Osman, F; Stein, DE; Renwick, A
MLA Citation
Ali-Osman, F, Stein, DE, and Renwick, A. "Glutathione content and glutathione-S-transferase expression in 1,3-bis(2-chloroethyl)-1-nitrosourea-resistant human malignant astrocytoma cell lines." Cancer Res 50.21 (November 1, 1990): 6976-6980.
PMID
2208164
Source
pubmed
Published In
Cancer Research
Volume
50
Issue
21
Publish Date
1990
Start Page
6976
End Page
6980

Stimulation and inhibition of 1,3-bis(2-chloroethyl)-1-nitrosourea-induced strand breaks and interstrand cross-linking in Col E1 plasmid deoxyribonucleic acid by polyamines and inorganic cations.

The influence of various polyamines and metallic cations on 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)-induced DNA single-strand breaks and DNA interstrand cross-linking was in Col E1 plasmid using electrophoretic techniques. Spermidine and spermine (0.4 to 1.5 mM concentration range) markedly stimulated BCNU-induced DNA nicking, whereas putrescine had no effect on the nicking process. In contrast to the polyamines, BCNU-induced DNA nicking was decreased by the three inorganic cations, Na+ (100 and 200 mM), Mg2+ (0.5 and 1.5 mM), and Co3+ (NH3)6 (0.2 and 0.4 mM), with the trivalent hexamminecobalt ions being most inhibitory. When the monofunctional N-methyl-N-nitrosourea (MNU) was used (instead of the bifunctionally active BCNU) to alkylate Col E1 DNA, nicking of the DNA was inhibited by spermidine. Furthermore, the ability of chloroethylated Col E1 DNA to form interstrand cross-links after treatment with BCU was inhibited by 0.5 mM spermidine and 0.5 mM spermine, both concentrations within the intracellular range. Putrescine at 3-6 mM only marginally stimulated DNA cross-linking. In comparison, the inorganic cations all enhanced Col E1 DNA cross-linking by BCNU, with the rank order of cross-link stimulation being Mg2+, Na+, and Co3+ (NH3)6. These results provide evidence that polyamines can interact with DNA to modulate chloroethylnitrosourea-induced DNA damage and that the interaction is not only a function of the charge on the polyamine molecule but also of the chemical structure of the polyamine.

Authors
Srivenugopal, KS; Ali-Osman, F
MLA Citation
Srivenugopal, KS, and Ali-Osman, F. "Stimulation and inhibition of 1,3-bis(2-chloroethyl)-1-nitrosourea-induced strand breaks and interstrand cross-linking in Col E1 plasmid deoxyribonucleic acid by polyamines and inorganic cations." Biochem Pharmacol 40.3 (August 1, 1990): 473-479.
PMID
2200407
Source
pubmed
Published In
Biochemical Pharmacology
Volume
40
Issue
3
Publish Date
1990
Start Page
473
End Page
479

Cellular and molecular studies in brain and nervous system oncology.

Authors
Ali-Osman, F; Schofield, D
MLA Citation
Ali-Osman, F, and Schofield, D. "Cellular and molecular studies in brain and nervous system oncology." Curr Opin Oncol 2.4 (August 1990): 655-665. (Review)
PMID
2095875
Source
pubmed
Published In
Current Opinion in Oncology
Volume
2
Issue
4
Publish Date
1990
Start Page
655
End Page
665

S1-nuclease enhancement of the ethidium bromide binding assay of drug-induced DNA interstrand crosslinking in human brain tumor cells.

A modification, using S1-nuclease, of a simple and sensitive fluorometric assay with ethidium bromide was developed for the measurement of cellular DNA interstrand crosslinking induced by bifunctional alkylators. Cells are lysed and treated with proteinase K and sodium dodecyl sulfate followed by extensive dialysis to yield intact high-molecular-weight DNA, free of contaminating proteins, on which the crosslink assay is then performed. The assay depends on the differential binding of ethidium bromide to single- and double-stranded DNA. Because of the higher ethidium bromide binding capacity of double-stranded DNA, the fluorescence retained after a heating/cooling cycle is directly proportional to the drug-induced cellular DNA interstrand crosslinking. We demonstrate that the sensitivity of this assay can be increased up to fourfold by including an S1-nuclease digestion step. This modified technique is simple and suited to the quantitation of low levels of DNA-interstrand crosslinking in cells.

Authors
Sriram, R; Ali-Osman, F
MLA Citation
Sriram, R, and Ali-Osman, F. "S1-nuclease enhancement of the ethidium bromide binding assay of drug-induced DNA interstrand crosslinking in human brain tumor cells." Anal Biochem 187.2 (June 1990): 345-348.
PMID
2200310
Source
pubmed
Published In
Analytical Biochemistry
Volume
187
Issue
2
Publish Date
1990
Start Page
345
End Page
348

DNA interstrand crosslinking and strand break repair in human glioma cell lines of varying [1,3-bis(2-chloroethyl)-1-nitrosourea] resistance.

The production of DNA interstrand crosslinks (ISC) by BCNU and other bifunctional alkylators and the effects of these drugs on the repair of radiation-induced DNA-single strand breaks (SSB) were studied in two human glioblastoma used to assess both DNA-ISCs and DNA-SSBs. BCNU-treated UWR2 and UWR3 cells showed a significant BCNU dose-dependent increase in radiation-induced DNA-SSBs at 6 hrs post-drug treatment, and at 100 microM BCNU DNA-ISC was completely masked in UWR2 cells. There was no enhancement of radiation-induced DNA-SSBs in both cell lines after treatment with cis-DDP, CHZ, or MNU. In the capillary clonogenic cell assay, UWR2 cells were 3.2 times more resistant than UWR3 cells; 0(6)-methylguanine-DNA methyltransferase activity was also 1.8 times higher in UWR2 than in UWR3. Our data suggest caution in the use of the standard alkaline elution technique (with 6 hrs between drug exposure and irradiation) to measure BCNU-induced DNA-ISC induction in highly BCNU-resistant cell lines. We provide evidence that the synergism between BCNU and radiation in the generation of DNA-SSBs is the result of low DNA-SSB repair capacity of the cells, and is further potentiated by the carbamoylating action of BCNU.

Authors
Ali-Osman, F; Srivenugopal, K; Berger, MS; Stein, DE
MLA Citation
Ali-Osman, F, Srivenugopal, K, Berger, MS, and Stein, DE. "DNA interstrand crosslinking and strand break repair in human glioma cell lines of varying [1,3-bis(2-chloroethyl)-1-nitrosourea] resistance." Anticancer Res 10.3 (May 1990): 677-682.
PMID
2164350
Source
pubmed
Published In
Anticancer research
Volume
10
Issue
3
Publish Date
1990
Start Page
677
End Page
682

Extracellular potassium influences DNA and protein syntheses and glial fibrillary acidic protein expression in cultured glial cells.

Previous reports of increases in glial cell number and expression of glial fibrillary acidic protein (GFAP) in stimulated brain regions or epileptic tissue have implicated a role for increases in extracellular potassium concentration ([K+]o) in glial reactions. We examined the effects of altered [K+]o on DNA and protein syntheses and GFAP expression of cultured glial cells isolated from the posthatch chick brain stem. [K+]o was varied by adding both KCl and NaCl to K+, NaCl-free medium to achieve final [K+] of 1-50 mM. DNA and protein syntheses were measured by incorporation of 3H-thymidine and 3H-leucine, respectively, into acid-insoluble material. GFAP expression was measured by a dot-immunoblotting assay. DNA syntheses in glial cells cultured in high (5-50 mM) K+o was 45-60% less than that of cells cultured in low (1-3 mM) K+o. Protein synthesis per cell was increased 34-44% in cells cultured in high K+ as compared to those cultured in low K+. GFAP expression was inversely related to [K+]o over the 1-10 mM range. Compared to the baseline of 3 mM K+o, GFAP per cell was increased 65% at 1 mM and decreased 45% at 10 mM. These data suggest that increases in glial cell number and GFAP immunoreactivity found in sites of increased neuronal activity and in pathological tissues may not be caused solely by persistent increases in [K+]o. Instead, these results suggest that neuronal activity, through the release of K+, may have an inhibitory influence on glial proliferation and GFAP expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Authors
Canady, KS; Ali-Osman, F; Rubel, EW
MLA Citation
Canady, KS, Ali-Osman, F, and Rubel, EW. "Extracellular potassium influences DNA and protein syntheses and glial fibrillary acidic protein expression in cultured glial cells." Glia 3.5 (1990): 368-374.
PMID
2146224
Source
pubmed
Published In
Glia
Volume
3
Issue
5
Publish Date
1990
Start Page
368
End Page
374
DOI
10.1002/glia.440030508

S1-nuclease enhancement of the ethidium bromide binding assay of drug-induced DNA interstrand crosslinking in human brain tumor cells

A modification, using S1-nuclease, of a simple and sensitive fluorometric assay with ethidium bromide was developed for the measurement of cellular DNA interstrand crosslinking induced by bifunctional alkylators. Cells are lysed and treated with proteinase K and sodium dodecyl sulfate followed by extensive dialysis to yield intact high-molecular-weight DNA, free of contaminating proteins, on which the crosslink assay is then performed. The assay depends on the differential binding of ethidium bromide to single- and double-stranded DNA. Because of the higher ethidium bromide binding capacity of double-stranded DNA, the fluorescence retained after a heating/cooling cycle is directly proportional to the drug-induced cellular DNA interstrand crosslinking. We demonstrate that the sensitivity of this assay can be increased up to fourfold by including an S1-nuclease digestion step. This modified technique is simple and suited to the quantitation of low levels of DNA-interstrand crosslinking in cells. © 1990.

Authors
Sriram, R; Ali-Osman, F
MLA Citation
Sriram, R, and Ali-Osman, F. "S1-nuclease enhancement of the ethidium bromide binding assay of drug-induced DNA interstrand crosslinking in human brain tumor cells." Analytical Biochemistry 187.2 (1990): 345-348.
Source
scival
Published In
Analytical Biochemistry
Volume
187
Issue
2
Publish Date
1990
Start Page
345
End Page
348
DOI
10.1016/0003-2697(90)90467-N

Decreased DNA interstrand cross-linking and cytotoxicity induced in human brain tumor cells by 1,3-bis(2-chloroethyl)-1-nitrosourea after in vitro reaction with glutathione.

Although both direct and glutathione S-transferase (GST)-catalyzed interactions between many electrophiles and GSH generally result in inactivation of the former, there are several reports of compounds whose electrophilic, alkylating, and cytotoxic activities are potentiated by GSH. This study investigates the effects of direct in vitro interaction between GSH and BCNU at physiological pH (7.2) and temperature (37 degrees C) and how this affects the cytotoxic and DNA cross-linking activity of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in target human malignant brain tumor cells. The kinetics and dose-response relationship of this interaction were determined by measuring residual GSH and residual BCNU-cytotoxicity in aGSH/BCNU mixture over a 45-min period and at varying BCNU concentrations. The results demonstrate that reaction of BCNU with four times its molar concentration of GSH for 45 min significantly inactivates BCNU, as expressed by a 32% decrease in induction of cellular DNA cross-linking, a 21% increase in DNA synthesis, and a 15% increase in clonogenic survival of human brain tumor cells compared to incubates of BCNU alone. Equine liver (EL)-GST increased the inactivation of BCNU only slightly (insignificant at p = 0.05). These results suggest that, in contrast to agents such as the alkyl-N-nitro-N'-nitrosoguanidines which become more potent alkylators after reacting with GSH, the 2-chloroethylnitrosoureas (CENUs) undergo inactivation by GSH. We propose that such interactions between GSH and the CENUs may constitute an important aspect of CENU metabolism and provide a potential means by which brain tumor cells can circumvent CENU toxicity and exhibit resistance to this class of agents.

Authors
Ali-Osman, F; Caughlan, J; Gray, GS
MLA Citation
Ali-Osman, F, Caughlan, J, and Gray, GS. "Decreased DNA interstrand cross-linking and cytotoxicity induced in human brain tumor cells by 1,3-bis(2-chloroethyl)-1-nitrosourea after in vitro reaction with glutathione." Cancer Res 49.21 (November 1, 1989): 5954-5958.
PMID
2551496
Source
pubmed
Published In
Cancer Research
Volume
49
Issue
21
Publish Date
1989
Start Page
5954
End Page
5958

Quenching of DNA cross-link precursors of chloroethylnitrosoureas and attenuation of DNA interstrand cross-linking by glutathione.

Interstrand DNA cross-linking is essential for the antitumor activity of chloroethylnitrosoureas (CENUs). The critical cross-links have been proposed to involve a rapid O6-guanine chloroethylation on one DNA strand, followed by a rearrangement of the O6-(2-chloroethyl)guanine and slow alkylation of the second DNA strand. In view of the relative intracellular abundance of glutathione (GSH) and nucleophilicity of its thiolate ion, the ability of GSH to react with and to inactivate 2-chlorethylated DNA and the possibility that this interaction decreases net DNA cross-linking by CENUs were investigated. Chloroethylated calf thymus DNA was reacted with GSH, the DNA was precipitated and redissolved, and subsequent DNA interstrand cross-linking was determined. The DNA cross-link index was compared for both GSH-treated and 2-chloroethylated untreated DNA. Simultaneously, Col E1 plasmid DNA was chloroethylated and reacted with GSH, and the extent of DNA interstrand cross-linking was determined by agarose gel electrophoresis and compared with controls. The results show both a time- and GSH concentration-dependent quenching of chloroethylated DNA, with a corresponding decrease in the DNA cross-link index. Using [methyl-3H]GSH, it was also demonstrated that 56% of the total GSH was bound to quenched 2-chloroethylated Col E1 DNA and 25% to quenched 2-chloroethylated calf thymus DNA. GSH binding to cross-linked DNA and native DNA was insignificant. It is concluded that, in addition to direct inactivation of reactive cytotoxic CENU species, GSH may also modulate cellular response to CENUs by quenching chloroethylated DNA, thereby decreasing the formation of potentially lethal DNA cross-links.

Authors
Ali-Osman, F
MLA Citation
Ali-Osman, F. "Quenching of DNA cross-link precursors of chloroethylnitrosoureas and attenuation of DNA interstrand cross-linking by glutathione." Cancer Res 49.19 (October 1, 1989): 5258-5261.
PMID
2766294
Source
pubmed
Published In
Cancer Research
Volume
49
Issue
19
Publish Date
1989
Start Page
5258
End Page
5261

Optimization and characterization of the capillary human tumor clonogenic cell assay.

The capillary human tumor clonogenic cell assay (HTCA) has been shown to have important advantages over conventional HTCAs. In the present report, this promising novel HTCA was further optimized and characterized using 46 primary human tumor specimens, 6 human tumor cell lines (1 astrocytoma, 2 colon carcinomas, 1 melanoma), and 2 murine leukemias. Hydrocortisone, epidermal growth factor, heat-inactivated fetal calf serum, and horse serum were investigated for their ability to modulate tumor colony formation in the assay. Critical assay parameters that can affect tumor colony formation, namely, cell seeding density, agarose concentration, culture volume, capillary tube geometry, and capillary tube sealing, were also investigated. The results showed that serum (optimum concentration, 20%) was obligatory for tumor colony formation, and that both epidermal growth factor (50 ng/ml) and hydrocortisone (2.5 ng/ml), although supportive of colony growth, were not absolute requirements. Plating at 2.5-3 x 10(5) cells/ml in a culture volume of 50 microliters/capillary tube and an agarose concentration of 0.2% optimized colony formation (number, size, and distribution of colonies along the capillary tube) by primary human tumor cells. The cell lines generally formed colonies best at lower seeding densities and in lower culture volumes (30 microliters/tube). Colony formation was significantly better in unsealed than in sealed capillary tubes and growth was just as good, and in some cases, better in round capillary tubes than in square ones. Using ovarian carcinoma cells, the Cellscan prototype system was demonstrated as feasible for automated counting and evaluation of tumor colony growth in capillary tubes. A comparison of the capillary HTCA and the agar double-layer assay in Petri dishes produced a median plating efficiency of 0.18 for the capillary HTCA and 0.036 for the Petri dish method. The overall success rate was 77% for the former and 53% for the latter assay.

Authors
Ali-Osman, F; Beltz, PA
MLA Citation
Ali-Osman, F, and Beltz, PA. "Optimization and characterization of the capillary human tumor clonogenic cell assay." Cancer Res 48.3 (February 1, 1988): 715-724.
PMID
3257171
Source
pubmed
Published In
Cancer Research
Volume
48
Issue
3
Publish Date
1988
Start Page
715
End Page
724

Application of in vivo and in vitro pharmacokinetics for physiologically relevant drug exposure in a human tumor clonogenic cell assay.

The biological half-lives and decay rate constants under the conditions of a human brain tumor clonogenic cell assay were determined for six clinically used anticancer agents. The agents studied were: 1,3-bis(2-chloroethyl)-1-nitrosourea; 3-(2-chloroethyl-3-nitrosoureido-2-deoxy-D-glucopyranose; cis-diaminedichloroplatinum(II); 2,5-diaziridinyl-3,6-bis-(carboethoxyamino)-1,4-benzoquinone; 4-demethylepipodophylotoxin-D-thylidene glucoside; and 9-hydroxy-2-N-methylellipticine. In vitro decay of all six drugs was found to be according to first order kinetics. The half-lives of two drugs, namely, 1,3-bis(2-chloroethyl-1-nitrosourea and 3-(2-chloroethyl-3-nitrosoureido-2-deoxy-D-glucopyranose under the human tumor clonogenic cell assay (HTCA) conditions were found to be similar to their terminal in vivo half-lives in humans. For the other drugs, however, there was a very large difference between their in vitro and in vivo pharmacokinetics. In the case of 2,5-diaziridinyl-3,6-bis(carboethoxyamine)-1,4-benzoquinone, we observed about an 80-fold difference between its in vitro half-life of 40.76 h and its in vivo terminal half-life of 0.52 h. We describe the principles upon which these data can be used to design clinically more relevant in vitro drug exposure protocols in HTCAs. Since, generally, tumor cells are exposed to drugs in the HTCA either continuously or for a specified duration, e.g., 1 or 2 h, we computed the initial in vitro drug concentrations to which tumor cells should be exposed such that the resulting in vitro (c X t) after a 2-h or a continuous exposure will be within clinically achievable levels. The application of these in vivo and in vitro pharmacokinetic principles will provide for more physiological testing of patient tumor cell sensitivity to anticancer drugs in the HTCA, and is likely to result in lower rates of false positive responses in clinical trials using clonogenic cell assays.

Authors
Ali-Osman, F; Giblin, J; Dougherty, D; Rosenblum, ML
MLA Citation
Ali-Osman, F, Giblin, J, Dougherty, D, and Rosenblum, ML. "Application of in vivo and in vitro pharmacokinetics for physiologically relevant drug exposure in a human tumor clonogenic cell assay." Cancer Res 47.14 (July 15, 1987): 3718-3724.
PMID
2954633
Source
pubmed
Published In
Cancer Research
Volume
47
Issue
14
Publish Date
1987
Start Page
3718
End Page
3724

Rapid method for permanent slide preparation of colonies in soft agar cultures.

A method is presented for preparing permanent microscopic slides from colony-bearing agar layers in soft agar cultures. The main advantages of this technique are its simplicity, rapidity and accurate colony preservation. This method could have broad applications in the human tumor clonogenic assay (HTCA), particularly in the quantitative morphological, cytochemical and immunocytochemical assessment of colonies that form in both control and drug-treated cultures. Thus, this method opens up possibilities for using cytopathological criteria as a quantitative endpoint of the HTCA.

Authors
Moezzi, J; Ali-Osman, F; Murphy, MJ
MLA Citation
Moezzi, J, Ali-Osman, F, and Murphy, MJ. "Rapid method for permanent slide preparation of colonies in soft agar cultures." Int J Cell Cloning 4.5 (September 1986): 368-374.
PMID
3534111
Source
pubmed
Published In
International Journal of Cell Cloning
Volume
4
Issue
5
Publish Date
1986
Start Page
368
End Page
374
DOI
10.1002/stem.5530040508

Relationship between histopathology and in vitro clonogenicity in breast cancer.

The human tumor clonogenic assay was used to culture 268 primary and metastatic breast cancer samples. Cultures of 181 specimens were prepared in the double-layer agar system and 87 in a modified system utilizing a liquid upper layer. Successful growth (greater than 5 colonies) was 53% for the agar 2-layer method and 68% for the modified system. Three morphologically distinct colony types were observed: Type I--small, dark, compact colonies; Type II--clear colonies; and Type III--mixed colonies of Types I and II. In 73 cases the histologic slides of the original tumor specimens were reviewed, and the histopathological findings correlated with the clonogenicity of the specimens. There was a significant positive relationship between the degree of differentiation and focal microscopic tumor necrosis in the original specimen and its subsequent clonogenicity. However, other histologic parameters did not show any relationship with clonogenicity.

Authors
Moezzi, J; Ali-Osman, F; Nicholson, GL; Ungerleider, JS; Murphy, MJ
MLA Citation
Moezzi, J, Ali-Osman, F, Nicholson, GL, Ungerleider, JS, and Murphy, MJ. "Relationship between histopathology and in vitro clonogenicity in breast cancer." Breast Cancer Res Treat 8.2 (1986): 147-156.
PMID
3814834
Source
pubmed
Published In
Breast Cancer Research and Treatment
Volume
8
Issue
2
Publish Date
1986
Start Page
147
End Page
156

Reculturing of cells from primary CFU-C colonies.

This study was aimed at investigating whether cells of CFU-C derived colonies could form secondary colonies. Bone marrow cultures of volumes of agar medium between 25 microliter and 75 microliter contained in glass capillaries were stimulated with mouse lung-conditioned medium (MLCM) containing granulocyte/macrophage colony-stimulating factor (GM-CSF). Agar gels with colonies of up to greater than or equal to 20 were blown out into identical culture medium, completely dispersed on a whirl-mix to single cell suspensions, and used for establishing secondary agar cultures. In these secondary cultures considerable numbers of secondary granulocytic, mixed granulocytic/macrophage and macrophage colonies as well as numerous clusters arose. In contrast, when single colonies were recultured, only few secondary cell aggregates were formed. When primary cultures containing up to greater than or equal to 20 cell aggregates were used for serial reculture at intermittent intervals of 3 and 4 days, a 2-7-fold increase of colony-forming cells was found in tertiary cultures as was monitored by 7 day colony counts. And by use of different kinds of CSF-containing media, an over 4-fold increase of secondary over primary colonies was obtained with bovine lung-conditioned medium (BLCM) in primary and L-cell-conditioned medium (LCCM) in secondary 7 day cultures. Primary capillary cultures were found to be devoid of CFU-S. Also, setting up bone marrow cultures in petri dishes and stimulating with MLCM, growth of primary as well as secondary colonies was obtained. The results indicate some self-renewal potential of CFU-C in vitro.

Authors
Hübner, GE; Ali-Osman, F; Kastner, M; Papadimitriou, C; Maurer, HR
MLA Citation
Hübner, GE, Ali-Osman, F, Kastner, M, Papadimitriou, C, and Maurer, HR. "Reculturing of cells from primary CFU-C colonies." Z Naturforsch C 40.11-12 (November 1985): 891-897.
PMID
3879569
Source
pubmed
Published In
Zeitschrift f�r Naturforschung. Section C: Biosciences
Volume
40
Issue
11-12
Publish Date
1985
Start Page
891
End Page
897

Chemical structure of carbamoylating groups and their relationship to bone marrow toxicity and antiglioma activity of bifunctionally alkylating and carbamoylating nitrosoureas.

Although the antitumor effects of chloroethylnitrosoureas have been shown to be due primarily to DNA-DNA cross-linking by the alkylating moieties of these agents, the basis of the often accompanying bone marrow toxicity has been more controversial. We report on the relative bone marrow toxicity of four model nitrosoureas with different alkylating and carbamoylating activities: 1,3-bis(2-chloroethyl)-1-nitrosourea; 1,3-bis(trans-4-hydroxycyclohexyl)-1-nitrosourea; chlorozotozin, (2-[3-(2-chloroethyl)-3 -nitrosoureido]-2-deoxy-D-glucopyranose); and -3-(beta-D-glucopyranosyl)-1-nitrosourea. Inhibitions of DNA, RNA, and protein synthesis in murine bone marrow cells and of colony growth of myeloid precursor cells (granulocyte-macrophage colony-forming units) were used as in vitro end points of myelotoxicity. Further, we determined the antiglioma activity of the four nitrosoureas on two human gliomas in a clonogenic tumor cell assay and studied the effect of the non-nitrosourea carbamoylators potassium cyanate, chloroethyl isocyanate, cyclohexyl isocyanate, ethyl isocyanate, and ethyl isothiocyanate on granulocyte-macrophage colony-forming units. The results show that, at equivalent drug exposures, clonogenic glioma cell kill was significant and comparative for 1,3-bis(2-chloroethyl)-1-nitrosourea, 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea, and chlorozotocin; 1,3-bis(trans-4-hydroxycyclohexyl)-1-nitrosourea showed little activity. In contrast, granulocyte-macrophage colony-forming unit toxicity was low with chlorozotocin and 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea and very high with 1,3-bis(2-chloroethyl)-1-nitrosourea and 1,3-bis(trans-4-hydroxycyclohexyl)-1-nitrosourea. Of the isocyanates, bone marrow toxicity was highest with chloroethyl isocyanate and cyclohexyl isocyanate, intermediate with ethyl isocyanate, and lowest with KOCN and ethyl isothiocyanate. Our results indicate that (a) bifunctional alkylation is essential for antiglioma activity of nitrosoureas and (b) myelosuppression is at least partly linked with carbamoylation but that structural entities in the carbamoylating isocyanate rather than a quantitative degree of carbamoylation determine the degree of potential myelotoxicity.

Authors
Ali-Osman, F; Giblin, J; Berger, M; Murphy, MJ; Rosenblum, ML
MLA Citation
Ali-Osman, F, Giblin, J, Berger, M, Murphy, MJ, and Rosenblum, ML. "Chemical structure of carbamoylating groups and their relationship to bone marrow toxicity and antiglioma activity of bifunctionally alkylating and carbamoylating nitrosoureas." Cancer Res 45.9 (September 1985): 4185-4191.
PMID
2411398
Source
pubmed
Published In
Cancer Research
Volume
45
Issue
9
Publish Date
1985
Start Page
4185
End Page
4191

Potential antiglioma activity of 9-hydroxy-2-N-methylellipticine as determined by pharmacological and human tumor clonogenic cell studies.

The antiglioma activity of elliptinium (HME) was investigated in a human glioma clonogenic cell assay. Early passage cells of three human glioma cell lines (SF126, SF375, and SF407) were exposed to HME at the clinically achievable dose of 3 microM for 3 h. At this HME concentration, clonogenic cell survival was reduced by more than 3 logs in SF126 and SF375, and by 0.8 logs in SF407. A study of the kinetics of cell kill showed that whereas at moderate (less than or equal to 1.5 microM) HME doses cell kill increased with treatment time up to a maximum at approximately 3 h, cytotoxicity was more dose than time dependent at higher doses. Flash treatment of SF375 cells with 3 microM HME resulted in more than 2 logs clonogenic cell kill. Using high-pressure liquid chromatography, we investigated the in vitro decay kinetics of HME under our in vitro drug treatment conditions and observed a very rapid, protein nondependent 40% drop in HME concentration which was dose dependent and was probably due to HME adsorption on the surface of tissue culture plasticware. Subsequent decay of the drug was very slow, with a decay rate constant of 0.022/h and a half-life of 298 h. In order to determine whether HME crosses the blood-brain barrier, we measured the rat brain capillary permeability coefficient, P, of [3H]HME and [14C]HME. The mean P value of 2.2 X 10(-6) cm/s +/- 16% (SD) suggests that HME crosses the blood-brain barrier (t 1/2 = 46 min) consistent with its molecular size and octanol-water partition coefficient.

Authors
Ali-Osman, F; Rosenblum, ML; Giannini, DD; Levin, VA
MLA Citation
Ali-Osman, F, Rosenblum, ML, Giannini, DD, and Levin, VA. "Potential antiglioma activity of 9-hydroxy-2-N-methylellipticine as determined by pharmacological and human tumor clonogenic cell studies." Cancer Res 45.7 (July 1985): 2988-2992.
PMID
4005838
Source
pubmed
Published In
Cancer Research
Volume
45
Issue
7
Publish Date
1985
Start Page
2988
End Page
2992

In vitro and in vivo investigations for the development of cytostatic methylhydrazones.

In in vitro short-term (3 h) assays, the beta-chloroethyl-methyl-hydrazones B 1 and B 2 inhibit the uptake of 3H-thymidine by EAC and L 1210 leukemia cells, B 2 being 5 to 10 times more effective than B 1. The growth inhibitory effect of both compounds was also confirmed in long-term (7 days) clonal assays using agar-containing glass capillaries, B 2 again being more effective than B 1. In contrast to these differences in vitro, in vivo both substances showed remission to the same degree in EAC- and complete resistance in L 1210-bearing mice. The diverging in vitro/in vivo sensitivities were thought to result from differences in the affinity of the methylhydrazones to the tumor cells: using short exposure periods (3 h) B 1 was more inhibitory than B 2 on both EAC and L 1210 colony growth; i.e., the more hydrophilic B 2 could more easily be washed off. To further test the idea of different cell membrane affinities, the methylhydrazones ZB 1 and P 1 with increasing lipophilic properties were synthesized. In vitro, after both pulse and continuous exposure ZB 1 and P 1 showed enforced inhibitory effects on colony growth. In vivo, ZB 1 and P 1 reduced the tumor weight of EAC mice, while only P 1 increased the survival time of L 1210 mice. The results suggest that from the combination of in vitro/in vivo assays mechanistic conclusions can be derived that are valuable for further development of these cystostatics.

Authors
Dittmar, W; Klitschka, G; Braun, R; Ali-Osman, F; Meckert, C; Maurer, HR
MLA Citation
Dittmar, W, Klitschka, G, Braun, R, Ali-Osman, F, Meckert, C, and Maurer, HR. "In vitro and in vivo investigations for the development of cytostatic methylhydrazones." J Cancer Res Clin Oncol 110.2 (1985): 110-114.
PMID
4044624
Source
pubmed
Published In
Journal of Cancer Research and Clinical Oncology
Volume
110
Issue
2
Publish Date
1985
Start Page
110
End Page
114

In vitro bone marrow cytotoxicity of nitrosoureas: Possible role for carbamoylation

Authors
Ali-Osman, F; Giblin, J; Berger, M
MLA Citation
Ali-Osman, F, Giblin, J, and Berger, M. "In vitro bone marrow cytotoxicity of nitrosoureas: Possible role for carbamoylation." Proceedings of the American Association for Cancer Research VOL. 26 (1985): No.-837.
Source
scival
Published In
Proceedings of the American Association for Cancer Research
Volume
VOL. 26
Publish Date
1985
Start Page
No.
End Page
837

Use of quinones in brain-tumor therapy: Preliminary results of preclinical laboratory investigations

Failure of current chemotherapeutic agents to effectively treat human brain tumors has prompted the search for alternative regimens based on the inherent metabolic pathways of target cells. One way to accomplish this goal would be to design drugs in an inactive form, which upon entry into the cell would be transformed to a toxic metabolite by a naturally occurring pathway. One such pathway may be the reductive activation of naphthoquinones with one or two side chains capable of alkylation, such as 2,3-dibromomethyl-1,4-naphthoquinone (DBNQ). This reductive activation can be catalyzed by the flavoprotein DT-diaphorase [NAD(P)H:quinone oxidoreductase]. We have found that both rat 9L and some human brain-tumor cell lines contain very high levels of this enzyme and that halogenated dimethyl naphthoquinones, such as DBNQ, are highly toxic to these cells in vitro. Moreover, we have found that the cytotoxic effects of DBNQ on human tumor and murine bone marrow stem cells can be prevented or lessened by pretreatment of the cells with dicoumarol, a potent inhibitor of DT-diaphorase. Since dicoumarol does not cross the blood-brain barrier, the potential exists for human brain tumors to be destroyed with halogenated dimethylquinones and for peripheral host toxicity to be prevented by coadministration of dicoumarol.

Authors
Berger, MS; Talcott, RE; Rosenblum, ML; Silva, M; AliOsman, F; Smith, MT
MLA Citation
Berger, MS, Talcott, RE, Rosenblum, ML, Silva, M, AliOsman, F, and Smith, MT. "Use of quinones in brain-tumor therapy: Preliminary results of preclinical laboratory investigations." Journal of Toxicology and Environmental Health 16.5 (1985): 713-719.
PMID
2419579
Source
scival
Published In
Journal of Toxicology and Environmental Health
Volume
16
Issue
5
Publish Date
1985
Start Page
713
End Page
719

Cytoprotection by somatostatin of normal and malignant clonogenic cells against the in vitro cytotoxicity of bischloroethylnitrosourea (BCNU).

The various pharmacological effects of somatostatin may be explained by the hypothesis that the paracrine peptide, by "stabilizing" cell membranes, inhibits the secretion of hormones as well as protects other cells (vascular endothelium, parenchyma) from different lesions (vasculo-, organo-, cytoprotection). This hypothesis was tested in vitro, using bischloroethyl-nitrosourea (BCNU)-intoxicated stem cells of normal mouse granulopoiesis and of the L 1210 leukemia. Clonogenic mouse bone marrow and L 1210 cells were grown in agar-containing glass capillaries. Using these colony assays and a ID90 of BCNU, cyclic somatostatin influenced the BCNU-cytotoxicity neither at simultaneous nor at subsequent application. However, when given 2 h prior to BCNU, the inhibition of colony growth was almost totally abolished. This cytoprotective effect was seen with normal granulopoietic as well as with leukemic cells. The effect did not show up, if the inactive linear somatostatin was used. N-acetyl-cysteine, a SH-compound applied as a chemoprotective adjunct, did not reveal a cytoprotective effect under identical experimental conditions, either. The results were discussed in view of common efforts to reduce the toxicity of cancer chemotherapy.

Authors
Maurer, HR; Meckert, C; Ali-Osman, F; Musil, J
MLA Citation
Maurer, HR, Meckert, C, Ali-Osman, F, and Musil, J. "Cytoprotection by somatostatin of normal and malignant clonogenic cells against the in vitro cytotoxicity of bischloroethylnitrosourea (BCNU)." Arzneimittelforschung 34.9 (1984): 939-943.
PMID
6150718
Source
pubmed
Published In
Arzneimittel-Forschung
Volume
34
Issue
9
Publish Date
1984
Start Page
939
End Page
943

Stimulation of clonal tumor cell growth in vitro by inhibiting the serum polyamine oxidase activity.

Several tumors are characterized by elevated levels of polyamines involved in vital cell proliferation processes. Polyamine oxidases (PAO), present in ruminant and particularily in fetal calf serum (FCS), degrade polyamines to polyaminoaldehydes and other products that inhibit cell proliferation. Since most in vitro assays for cloning tumor stem cells use FCS as an essential supplement of the nutrient media, we examined the effects of specifically inhibiting the PAO activity on the clonal growth of leukemic cells and the following normal lymphocytes: the W 25 rat chloroleukemia, the M1 mouse myeloblastic and the L 1210 rat lymphoblastic leukemia, a primary human acute myeloblastic leukemia (AML) and acute lymphocytic leukemia (ALL) as well as normal human PHA-stimulated lymphocytes. In the presence od horse serum, nontoxic doses of the PAO inhibitor 1-hydroxybenzyloxyamine did not affect colony growth of either cell type. However, in the presence of FCS, clonal growth of W 25, ALL, AML, and PHA lymphocytes was significantly stimulated by the enzyme inhibitor. Our data suggest (a) that poor cell proliferation of several tumors in vitro may result from the reaction of polyamines (from cells) and PAO (from serum), (b) that this can be easily tested by means of a specific PAO inhibitor, and (c) that the growth conditions can be optimized by adding nontoxic doses of the enzyme inhibitor or by exchanging FCS for another serum.

Authors
Ali-Osman, F; Maurer, HR
MLA Citation
Ali-Osman, F, and Maurer, HR. "Stimulation of clonal tumor cell growth in vitro by inhibiting the serum polyamine oxidase activity." J Cancer Res Clin Oncol 106.1 (1983): 17-20.
PMID
6885895
Source
pubmed
Published In
Journal of Cancer Research and Clinical Oncology
Volume
106
Issue
1
Publish Date
1983
Start Page
17
End Page
20

Correlation of intralesional in vivo chemotherapy of line 10 hepatoma with in vitro drug sensitivity

Authors
Osman, FA; Bier, J; Bier, H; Siegel, T; Maurer, HR; Ohanian, S
MLA Citation
Osman, FA, Bier, J, Bier, H, Siegel, T, Maurer, HR, and Ohanian, S. "Correlation of intralesional in vivo chemotherapy of line 10 hepatoma with in vitro drug sensitivity." International Journal of Cell Cloning 1.2 (1983): 118-127.
PMID
6199438
Source
scival
Published In
International Journal of Cell Cloning
Volume
1
Issue
2
Publish Date
1983
Start Page
118
End Page
127

In vitro cytostatic drug sensitivity testing in the human tumor stem cell assay: A modified method for the determination of the sensitivity index

Authors
Osman, FA; Maurer, HR; Bier, J
MLA Citation
Osman, FA, Maurer, HR, and Bier, J. "In vitro cytostatic drug sensitivity testing in the human tumor stem cell assay: A modified method for the determination of the sensitivity index." Tumor Diagnostik und Therapie 4.1 (1983): 1-6.
Source
scival
Published In
Tumor Diagnostik und Therapie
Volume
4
Issue
1
Publish Date
1983
Start Page
1
End Page
6

Two different types of granulocyte colony-stimulating factor produced by bovine lung tissue.

Bovine lung tissue produces two different types of granulocyte colony-stimulating factor (CSF). The high molecular weight (MW) type (CSF-F) of 70,000 d by Sephadex G-100 gel filtration is only found in conditioned medium of homogenized tissue incubated in sealed glass bottles. The species of CSF exclusively stimulates CFU-C of mouse bone marrow, human bone marrow only hardly. The low MW type CSF (CSF-M) of approximately 29,000 d by gel filtration is found mainly in conditioned medium of slightly minced tissue incubated in Petri dishes. It stimulates both human and mouse CFU-C. Methods to prepare both types of CSF are described. By propagating a fibroblast cell line from bovine lung tissue it was found that fibroblasts are the source of the 70,000 d CSF. Indirect evidence suggests that macrophages produce the 29,000 d CSF species.

Authors
Neumeier, R; Ali-Osman, F; Maurer, HR
MLA Citation
Neumeier, R, Ali-Osman, F, and Maurer, HR. "Two different types of granulocyte colony-stimulating factor produced by bovine lung tissue." Blut 44.1 (January 1982): 21-27.
PMID
6977391
Source
pubmed
Published In
Blut
Volume
44
Issue
1
Publish Date
1982
Start Page
21
End Page
27

Tumor stem cell cloning in agar-containing capillaries.

Authors
Maurer, HR; Ali-Osman, F
MLA Citation
Maurer, HR, and Ali-Osman, F. "Tumor stem cell cloning in agar-containing capillaries." Naturwissenschaften 68.7 (July 1981): 381-383.
PMID
7266677
Source
pubmed
Published In
Naturwissenschaften
Volume
68
Issue
7
Publish Date
1981
Start Page
381
End Page
383

Comparison of cytostatic sensitivities of L 1210 cells and human stimulated lymphocytes in three cell proliferation assays.

Three methods of measuring cell proliferation, viz., cellular H-thymidine uptake, counting of cells in suspension, and counting of colonies of cells grown in agar contained in glass capillaries, were compared by studying cell growth kinetics using the L 1210 cell line. We found the agar colony culture method to be most suitable and methodologically most advantageous. Using these cytokinetic models, we investigated the differential sensitivities of exponential and stationary phase L 1210 cells and normal, human, PHA-stimulated, peripheral T-lymphocytes to methotrexate, cytosine arabinoside, azathioprine, and a partially purified lymphocyte chalone preparation. L 1210 cells in exponential growth showed a higher drug sensitivity to all the agents tested than those in stationary growth. Normal, human T-lymphocytes exhibited less sensitivity to the tested agents. We found the agar culture to be more than twice as sensitive as the suspension culture and up to 8-fold more sensitive than the 3H-thymidine uptake method.

Authors
Ali-Osman, F; Maurer, HR
MLA Citation
Ali-Osman, F, and Maurer, HR. "Comparison of cytostatic sensitivities of L 1210 cells and human stimulated lymphocytes in three cell proliferation assays." J Cancer Res Clin Oncol 98.3 (1980): 221-231.
PMID
6453124
Source
pubmed
Published In
Journal of Cancer Research and Clinical Oncology
Volume
98
Issue
3
Publish Date
1980
Start Page
221
End Page
231

Comparative cell kinetic studies of the L1210 leukemic line differential, effects of cytostatics and a lymphocyte chalone extract on this cell line and on peripheral human lymphocytes after PHA-stimulation

Authors
Osman, FA; Maurer, HR
MLA Citation
Osman, FA, and Maurer, HR. "Comparative cell kinetic studies of the L1210 leukemic line differential, effects of cytostatics and a lymphocyte chalone extract on this cell line and on peripheral human lymphocytes after PHA-stimulation." Cell and Tissue Kinetics 13.2 (1980): 208--.
Source
scival
Published In
Cell and Tissue Kinetics
Volume
13
Issue
2
Publish Date
1980
Start Page
208-
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