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Kastan, Michael Barry

Positions:

William and Jane Shingleton Professor of Pharmacology and Cancer Biology

Pharmacology & Cancer Biology
School of Medicine

Professor of Pharmacology and Cancer Biology

Pharmacology & Cancer Biology
School of Medicine

Professor of Pediatrics

Pediatrics
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Director of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

M.D. 1984

M.D. — Washington University

Ph.D. 1984

Ph.D. — Washington University

News:

Grants:

Evaluation of kinase inhibitors

Administered By
Pharmacology & Cancer Biology
AwardedBy
XRAD THERAPEUTICS, INC.
Role
Principal Investigator
Start Date
August 19, 2016
End Date
August 18, 2021

The role of ATM in Metabolic Stress Responses

Administered By
Pharmacology & Cancer Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
January 01, 2011
End Date
June 30, 2021

Pharmacological Sciences Training Program

Administered By
Pharmacology & Cancer Biology
AwardedBy
National Institutes of Health
Role
Participating Faculty Member
Start Date
July 01, 1975
End Date
June 30, 2020

NINDS Research Education Programs for Residents and Fellows in Neurosurgery

Administered By
Neurosurgery
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
March 01, 2009
End Date
June 30, 2019

Duke University Program in Environmental Health

Administered By
Environmental Sciences and Policy
AwardedBy
National Institute of Environmental Health Sciences
Role
Mentor
Start Date
July 01, 2013
End Date
June 30, 2018

Cellular Stress Response Signaling Pathways

Administered By
Pharmacology & Cancer Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
January 01, 1992
End Date
May 31, 2018

Identification of Therapeutic Interventions in Ataxia-Telangiectasia Using a Novel Model of Metabolic Stress

Administered By
Pharmacology & Cancer Biology
AwardedBy
University of Pennsylvania
Role
Principal Investigator
Start Date
January 01, 2017
End Date
December 31, 2017

C30 Canine Pilot Research

Administered By
Duke Cancer Institute
AwardedBy
V Foundation for Cancer Research
Role
Principal Investigator
Start Date
July 01, 2016
End Date
December 31, 2017

Developing Capacity for Burkett Lymphoma Clinical Research in Tanzania

Administered By
Duke Cancer Institute
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
September 01, 1976
End Date
December 31, 2017

Center for Molecular & Cellular Studies of Ped Disease

Administered By
Pediatrics
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
April 11, 2003
End Date
November 30, 2017

Using bacterial CRISPR/Cas endonucleases to selectively eliminate HPV-transformed cells in vivo

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
September 02, 2015
End Date
August 31, 2017

Medical Scientist Training Program

Administered By
School of Medicine
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
July 01, 1997
End Date
June 30, 2017

Development and Validation of Novel Therapeutic Targets in Anal Cancer

Administered By
Medicine, Medical Oncology
AwardedBy
The Farrah Fawcett Foundation
Role
Collaborator
Start Date
January 01, 2015
End Date
December 31, 2016

Metabolic Sensing and Stress Response Deficit in Ataxia Telangiectasia

Administered By
Pharmacology & Cancer Biology
AwardedBy
A-T Children's Project
Role
Principal Investigator
Start Date
August 01, 2014
End Date
July 31, 2016

Chromatin Modulation Associated with DNA Breakage and Repair in Human Cells

Administered By
Pharmacology & Cancer Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2011
End Date
April 30, 2016

Cancer Biology Training Grant

Administered By
Pharmacology & Cancer Biology
AwardedBy
National Cancer Institute
Role
Mentor
Start Date
July 01, 1993
End Date
March 31, 2016

Evaluating GSK2126458 with radiation therapy in pre-clinical models

Administered By
Radiation Oncology
AwardedBy
GlaxoSmithKline
Role
Co-Principal Investigator
Start Date
November 14, 2013
End Date
November 14, 2015

Screening for ATM/DNA-PK inhibitors

Administered By
Pharmacology & Cancer Biology
AwardedBy
GlaxoSmithKline
Role
Principal Investigator
Start Date
November 26, 2014
End Date
August 25, 2015
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Awards:

Member. National Academy of Sciences.

Type
National
Awarded By
National Academy of Sciences
Date
January 01, 2016

Member. Institute of Medicine of The National Academies.

Type
National
Awarded By
Institute of Medicine of The National Academies
Date
January 01, 2009

Publications:

Identification of a DNA Damage-induced Alternative Splicing Pathway that Regulates p53 and Cellular Senescence Markers.

Cellular responses to DNA damage are critical determinants of cancer development and aging-associated pathogenesis. Here we report a novel DNA damage response pathway that regulates alternative splicing of numerous gene products, including the human tumor suppressor p53, and controls DNA damage-induced cellular senescence. In brief, ionizing irradiation (IR) inhibits the activity of hSMG-1, a phosphoinositide-3-kinase-like kinase (PIKK) family member, reducing the binding of hSMG1 to a specific region of p53 precursor mRNA near exon 9 and promoting the binding of ribosomal protein L26 (RPL26) to p53 pre-mRNA. RPL26, in turn, is required for the recruitment of the Serine/Arginine-rich splicing factor, SRSF7, to p53 pre-mRNA and generation of alternatively spliced p53 RNA. Disruption of this pathway via selective knockout of p53β by CRISPR/Cas9 or down-regulation of pathway constituents significantly reduces IR-induced senescence markers and cells lacking p53β expression fail to transcriptionally repress negative regulators of cellular senescence and aging.

Authors
Chen, J; Crutchley, J; Zhang, D; Owzar, K; Kastan, MB
MLA Citation
Chen, J, Crutchley, J, Zhang, D, Owzar, K, and Kastan, MB. "Identification of a DNA Damage-induced Alternative Splicing Pathway that Regulates p53 and Cellular Senescence Markers." Cancer discovery (March 13, 2017).
PMID
28288992
Source
epmc
Published In
Cancer Discovery
Publish Date
2017
DOI
10.1158/2159-8290.cd-16-0908

Commentary on "Participation of p53 Protein in the Cellular Response to DNA Damage".

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Commentary on "Participation of p53 Protein in the Cellular Response to DNA Damage"." Cancer research 76.13 (July 2016): 3663-3665.
PMID
27371738
Source
epmc
Published In
Cancer Research
Volume
76
Issue
13
Publish Date
2016
Start Page
3663
End Page
3665
DOI
10.1158/0008-5472.can-16-1560

Perspectives from man's best friend: National Academy of Medicine's Workshop on Comparative Oncology.

Authors
LeBlanc, AK; Breen, M; Choyke, P; Dewhirst, M; Fan, TM; Gustafson, DL; Helman, LJ; Kastan, MB; Knapp, DW; Levin, WJ; London, C; Mason, N; Mazcko, C; Olson, PN; Page, R; Teicher, BA; Thamm, DH; Trent, JM; Vail, DM; Khanna, C
MLA Citation
LeBlanc, AK, Breen, M, Choyke, P, Dewhirst, M, Fan, TM, Gustafson, DL, Helman, LJ, Kastan, MB, Knapp, DW, Levin, WJ, London, C, Mason, N, Mazcko, C, Olson, PN, Page, R, Teicher, BA, Thamm, DH, Trent, JM, Vail, DM, and Khanna, C. "Perspectives from man's best friend: National Academy of Medicine's Workshop on Comparative Oncology." Science translational medicine 8.324 (February 2016): 324ps5-.
PMID
26843188
Source
epmc
Published In
Science Translational Medicine
Volume
8
Issue
324
Publish Date
2016
Start Page
324ps5
DOI
10.1126/scitranslmed.aaf0746

Optimization of a Novel Series of Ataxia-Telangiectasia Mutated Kinase Inhibitors as Potential Radiosensitizing Agents.

We previously reported a novel inhibitor of the ataxia-telangiectasia mutated (ATM) kinase, which is a target for novel radiosensitizing drugs. While our initial lead, compound 4, was relatively potent and nontoxic, it exhibited poor stability to oxidative metabolism and relatively poor selectivity against other kinases. The current study focused on balancing potency and selectivity with metabolic stability through structural modification to the metabolized site on the quinazoline core. We performed extensive structure-activity and structure-property relationship studies on this quinazoline ATM kinase inhibitor in order to identify structural variants with enhanced selectivity and metabolic stability. We show that, while the C-7-methoxy group is essential for potency, replacing the C-6-methoxy group considerably improves metabolic stability without affecting potency. Promising analogues 20, 27g, and 27n were selected based on in vitro pharmacology and evaluated in murine pharmacokinetic and tolerability studies. Compound 27g possessed significantly improve pharmacokinetics relative to that of 4. Compound 27g was also significantly more selective against other kinases than 4. Therefore, 27g is a good candidate for further development as a potential radiosensitizer.

Authors
Min, J; Guo, K; Suryadevara, PK; Zhu, F; Holbrook, G; Chen, Y; Feau, C; Young, BM; Lemoff, A; Connelly, MC; Kastan, MB; Guy, RK
MLA Citation
Min, J, Guo, K, Suryadevara, PK, Zhu, F, Holbrook, G, Chen, Y, Feau, C, Young, BM, Lemoff, A, Connelly, MC, Kastan, MB, and Guy, RK. "Optimization of a Novel Series of Ataxia-Telangiectasia Mutated Kinase Inhibitors as Potential Radiosensitizing Agents." Journal of medicinal chemistry 59.2 (January 2016): 559-577.
PMID
26632965
Source
epmc
Published In
Journal of Medicinal Chemistry
Volume
59
Issue
2
Publish Date
2016
Start Page
559
End Page
577
DOI
10.1021/acs.jmedchem.5b01092

Chromatin perturbations during the DNA damage response in higher eukaryotes.

The DNA damage response is a widely used term that encompasses all signaling initiated at DNA lesions and damaged replication forks as it extends to orchestrate DNA repair, cell cycle checkpoints, cell death and senescence. ATM, an apical DNA damage signaling kinase, is virtually instantaneously activated following the introduction of DNA double-strand breaks (DSBs). The MRE11-RAD50-NBS1 (MRN) complex, which has a catalytic role in DNA repair, and the KAT5 (Tip60) acetyltransferase are required for maximal ATM kinase activation in cells exposed to low doses of ionizing radiation. The sensing of DNA lesions occurs within a highly complex and heterogeneous chromatin environment. Chromatin decondensation and histone eviction at DSBs may be permissive for KAT5 binding to H3K9me3 and H3K36me3, ATM kinase acetylation and activation. Furthermore, chromatin perturbation may be a prerequisite for most DNA repair. Nucleosome disassembly during DNA repair was first reported in the 1970s by Smerdon and colleagues when nucleosome rearrangement was noted during the process of nucleotide excision repair of UV-induced DNA damage in human cells. Recently, the multi-functional protein nucleolin was identified as the relevant histone chaperone required for partial nucleosome disruption at DBSs, the recruitment of repair enzymes and for DNA repair. Notably, ATM kinase is activated by chromatin perturbations induced by a variety of treatments that do not directly cause DSBs, including treatment with histone deacetylase inhibitors. Central to the mechanisms that activate ATR, the second apical DNA damage signaling kinase, outside of a stalled and collapsed replication fork in S-phase, is chromatin decondensation and histone eviction associated with DNA end resection at DSBs. Thus, a stress that is common to both ATM and ATR kinase activation is chromatin perturbations, and we argue that chromatin perturbations are both sufficient and required for induction of the DNA damage response.

Authors
Bakkenist, CJ; Kastan, MB
MLA Citation
Bakkenist, CJ, and Kastan, MB. "Chromatin perturbations during the DNA damage response in higher eukaryotes." DNA repair 36 (December 2015): 8-12. (Review)
PMID
26391293
Source
epmc
Published In
DNA Repair
Volume
36
Publish Date
2015
Start Page
8
End Page
12
DOI
10.1016/j.dnarep.2015.09.002

ATM functions at the peroxisome to induce pexophagy in response to ROS.

Peroxisomes are highly metabolic, autonomously replicating organelles that generate reactive oxygen species (ROS) as a by-product of fatty acid β-oxidation. Consequently, cells must maintain peroxisome homeostasis, or risk pathologies associated with too few peroxisomes, such as peroxisome biogenesis disorders, or too many peroxisomes, inducing oxidative damage and promoting diseases such as cancer. We report that the PEX5 peroxisome import receptor binds ataxia-telangiectasia mutated (ATM) and localizes this kinase to the peroxisome. In response to ROS, ATM signalling activates ULK1 and inhibits mTORC1 to induce autophagy. Specificity for autophagy of peroxisomes (pexophagy) is provided by ATM phosphorylation of PEX5 at Ser 141, which promotes PEX5 monoubiquitylation at Lys 209, and recognition of ubiquitylated PEX5 by the autophagy adaptor protein p62, directing the autophagosome to peroxisomes to induce pexophagy. These data reveal an important new role for ATM in metabolism as a sensor of ROS that regulates pexophagy.

Authors
Zhang, J; Tripathi, DN; Jing, J; Alexander, A; Kim, J; Powell, RT; Dere, R; Tait-Mulder, J; Lee, J-H; Paull, TT; Pandita, RK; Charaka, VK; Pandita, TK; Kastan, MB; Walker, CL
MLA Citation
Zhang, J, Tripathi, DN, Jing, J, Alexander, A, Kim, J, Powell, RT, Dere, R, Tait-Mulder, J, Lee, J-H, Paull, TT, Pandita, RK, Charaka, VK, Pandita, TK, Kastan, MB, and Walker, CL. "ATM functions at the peroxisome to induce pexophagy in response to ROS." Nature cell biology 17.10 (October 2015): 1259-1269.
PMID
26344566
Source
epmc
Published In
Nature Cell Biology
Volume
17
Issue
10
Publish Date
2015
Start Page
1259
End Page
1269
DOI
10.1038/ncb3230

Repair versus Checkpoint Functions of BRCA1 Are Differentially Regulated by Site of Chromatin Binding.

The product of the Brca1 tumor-suppressor gene is involved in multiple aspects of the cellular DNA damage response (DDR), including activation of cell-cycle arrests and DNA double-stranded break (DSB) repair by homologous recombination. Prior reports demonstrated that BRCA1 recruitment to areas of DNA breakage depended on RAP80 and the RNF8/RNF168 E3 ubiquitin ligases. Here, we extend these findings by showing that RAP80 is only required for the binding of BRCA1 to regions flanking the DSB, whereas BRCA1 binding directly to DNA breaks requires Nijmegen breakage syndrome 1 (NBS1). These differential recruitment mechanisms differentially affect BRCA1 functions: (i) RAP80-dependent recruitment of BRCA1 to chromatin flanking DNA breaks is required for BRCA1 phosphorylation at serine 1387 and 1423 by ATM and, consequently, for the activation of S and G(2) checkpoints; and (ii) BRCA1 interaction with NBS1 upon DSB induction results in an NBS1-dependent recruitment of BRCA1 directly to the DNA break and is required for nonhomologous end-joining repair. Together, these findings illustrate that spatially distinct fractions of BRCA1 exist at the DSB site, which are recruited by different mechanisms and execute different functions in the DDR.

Authors
Goldstein, M; Kastan, MB
MLA Citation
Goldstein, M, and Kastan, MB. "Repair versus Checkpoint Functions of BRCA1 Are Differentially Regulated by Site of Chromatin Binding." Cancer research 75.13 (July 2015): 2699-2707.
PMID
25939603
Source
epmc
Published In
Cancer Research
Volume
75
Issue
13
Publish Date
2015
Start Page
2699
End Page
2707
DOI
10.1158/0008-5472.can-15-0400

HIF-1 Alpha Regulates the Response of Primary Sarcomas to Radiation Therapy through a Cell Autonomous Mechanism.

Hypoxia is a major cause of radiation resistance, which may predispose to local recurrence after radiation therapy. While hypoxia increases tumor cell survival after radiation exposure because there is less oxygen to oxidize damaged DNA, it remains unclear whether signaling pathways triggered by hypoxia contribute to radiation resistance. For example, intratumoral hypoxia can increase hypoxia inducible factor 1 alpha (HIF-1α), which may regulate pathways that contribute to radiation sensitization or radiation resistance. To clarify the role of HIF-1α in regulating tumor response to radiation, we generated a novel genetically engineered mouse model of soft tissue sarcoma with an intact or deleted HIF-1α. Deletion of HIF-1α sensitized primary sarcomas to radiation exposure in vivo. Moreover, cell lines derived from primary sarcomas lacking HIF-1α, or in which HIF-1α was knocked down, had decreased clonogenic survival in vitro, demonstrating that HIF-1α can promote radiation resistance in a cell autonomous manner. In HIF-1α-intact and -deleted sarcoma cells, radiation-induced reactive oxygen species, DNA damage repair and activation of autophagy were similar. However, sarcoma cells lacking HIF-1α had impaired mitochondrial biogenesis and metabolic response after irradiation, which might contribute to radiation resistance. These results show that HIF-1α promotes radiation resistance in a cell autonomous manner.

Authors
Zhang, M; Qiu, Q; Li, Z; Sachdeva, M; Min, H; Cardona, DM; DeLaney, TF; Han, T; Ma, Y; Luo, L; Ilkayeva, OR; Lui, K; Nichols, AG; Newgard, CB; Kastan, MB; Rathmell, JC; Dewhirst, MW; Kirsch, DG
MLA Citation
Zhang, M, Qiu, Q, Li, Z, Sachdeva, M, Min, H, Cardona, DM, DeLaney, TF, Han, T, Ma, Y, Luo, L, Ilkayeva, OR, Lui, K, Nichols, AG, Newgard, CB, Kastan, MB, Rathmell, JC, Dewhirst, MW, and Kirsch, DG. "HIF-1 Alpha Regulates the Response of Primary Sarcomas to Radiation Therapy through a Cell Autonomous Mechanism." Radiation research 183.6 (June 2015): 594-609.
PMID
25973951
Source
epmc
Published In
Radiation Research
Volume
183
Issue
6
Publish Date
2015
Start Page
594
End Page
609
DOI
10.1667/rr14016.1

Duke University Global Cancer Program: A multidisciplinary approach to partnerships in global cancer care

Authors
Musselwhite, LW; Schroeder, K; Bhattacharya, M; Vanderburg, SB; Masalu, NA; Chandy, M; Mauad, E; Bartlett, J; Kastan, MB; Merson, M; Chao, NJA
MLA Citation
Musselwhite, LW, Schroeder, K, Bhattacharya, M, Vanderburg, SB, Masalu, NA, Chandy, M, Mauad, E, Bartlett, J, Kastan, MB, Merson, M, and Chao, NJA. "Duke University Global Cancer Program: A multidisciplinary approach to partnerships in global cancer care." May 20, 2015.
Source
wos-lite
Published In
Journal of Clinical Oncology
Volume
33
Issue
15
Publish Date
2015

The DNA damage response: implications for tumor responses to radiation and chemotherapy.

Cellular responses to DNA damage are important determinants of both cancer development and cancer outcome following radiation therapy and chemotherapy. Identification of molecular pathways governing DNA damage signaling and DNA repair in response to different types of DNA lesions allows for a better understanding of the effects of radiation and chemotherapy on normal and tumor cells. Although dysregulation of the DNA damage response (DDR) is associated with predisposition to cancer development, it can also result in hypersensitivity or resistance of tumors to therapy and can be exploited for improvement of cancer treatment. We highlight the DDR pathways that are activated after treatment with radiation and different classes of chemotherapeutic drugs and describe mechanisms determining tumor sensitivity and resistance to these agents. Further, we discuss approaches to enhance tumor sensitivity to radiation and chemotherapy by modulating the DDR with a goal of enhancing the effectiveness of cancer therapies.

Authors
Goldstein, M; Kastan, MB
MLA Citation
Goldstein, M, and Kastan, MB. "The DNA damage response: implications for tumor responses to radiation and chemotherapy." Annual review of medicine 66 (January 2015): 129-143.
PMID
25423595
Source
epmc
Published In
Annual Review of Medicine
Volume
66
Publish Date
2015
Start Page
129
End Page
143
DOI
10.1146/annurev-med-081313-121208

Abstract IA11: New insights into DNA double-strand break responses

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Abstract IA11: New insights into DNA double-strand break responses." December 1, 2014.
Source
crossref
Published In
Cancer Research
Volume
74
Issue
23 Supplement
Publish Date
2014
Start Page
IA11
End Page
IA11
DOI
10.1158/1538-7445.CANSUSC14-IA11

The scaffold protein WRAP53β orchestrates the ubiquitin response critical for DNA double-strand break repair.

The WD40 domain-containing protein WRAP53β (WD40 encoding RNA antisense to p53; also referred to as WDR79/TCAB1) controls trafficking of splicing factors and the telomerase enzyme to Cajal bodies, and its functional loss has been linked to carcinogenesis, premature aging, and neurodegeneration. Here, we identify WRAP53β as an essential regulator of DNA double-strand break (DSB) repair. WRAP53β rapidly localizes to DSBs in an ATM-, H2AX-, and MDC1-dependent manner. We show that WRAP53β targets the E3 ligase RNF8 to DNA lesions by facilitating the interaction between RNF8 and its upstream partner, MDC1, in response to DNA damage. Simultaneous binding of MDC1 and RNF8 to the highly conserved WD40 scaffold domain of WRAP53β facilitates their interaction and accumulation of RNF8 at DSBs. In this manner, WRAP53β controls proper ubiquitylation at DNA damage sites and the downstream assembly of 53BP1, BRCA1, and RAD51. Furthermore, we reveal that knockdown of WRAP53β impairs DSB repair by both homologous recombination (HR) and nonhomologous end-joining (NHEJ), causes accumulation of spontaneous DNA breaks, and delays recovery from radiation-induced cell cycle arrest. Our findings establish WRAP53β as a novel regulator of DSB repair by providing a scaffold for DNA repair factors.

Authors
Henriksson, S; Rassoolzadeh, H; Hedström, E; Coucoravas, C; Julner, A; Goldstein, M; Imreh, G; Zhivotovsky, B; Kastan, MB; Helleday, T; Farnebo, M
MLA Citation
Henriksson, S, Rassoolzadeh, H, Hedström, E, Coucoravas, C, Julner, A, Goldstein, M, Imreh, G, Zhivotovsky, B, Kastan, MB, Helleday, T, and Farnebo, M. "The scaffold protein WRAP53β orchestrates the ubiquitin response critical for DNA double-strand break repair." Genes & development 28.24 (December 2014): 2726-2738.
PMID
25512560
Source
epmc
Published In
Genes & development
Volume
28
Issue
24
Publish Date
2014
Start Page
2726
End Page
2738
DOI
10.1101/gad.246546.114

Abstract IA08: Ataxia-telangiectasia: Broad implications from the study of a rare disease

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Abstract IA08: Ataxia-telangiectasia: Broad implications from the study of a rare disease." Cancer Research 74.20 Supplement (October 15, 2014): IA08-IA08.
Source
crossref
Published In
Cancer Research
Volume
74
Issue
20 Supplement
Publish Date
2014
Start Page
IA08
End Page
IA08
DOI
10.1158/1538-7445.PEDCAN-IA08

Inactivation of the human papillomavirus E6 or E7 gene in cervical carcinoma cells by using a bacterial CRISPR/Cas RNA-guided endonuclease.

High-risk human papillomaviruses (HPVs), including HPV-16 and HPV-18, are the causative agents of cervical carcinomas and are linked to several other tumors of the anogenital and oropharyngeal regions. The majority of HPV-induced tumors contain integrated copies of the normally episomal HPV genome that invariably retain intact forms of the two HPV oncogenes E6 and E7. E6 induces degradation of the cellular tumor suppressor p53, while E7 destabilizes the retinoblastoma (Rb) protein. Previous work has shown that loss of E6 function in cervical cancer cells induces p53 expression as well as downstream effectors that induce apoptosis and cell cycle arrest. Similarly, loss of E7 allows increased Rb expression, leading to cell cycle arrest and senescence. Here, we demonstrate that expression of a bacterial Cas9 RNA-guided endonuclease, together with single guide RNAs (sgRNAs) specific for E6 or E7, is able to induce cleavage of the HPV genome, resulting in the introduction of inactivating deletion and insertion mutations into the E6 or E7 gene. This results in the induction of p53 or Rb, leading to cell cycle arrest and eventual cell death. Both HPV-16- and HPV-18-transformed cells were found to be responsive to targeted HPV genome-specific DNA cleavage. These data provide a proof of principle for the idea that vector-delivered Cas9/sgRNA combinations could represent effective treatment modalities for HPV-induced cancers. Importance: Human papillomaviruses (HPVs) are the causative agents of almost all cervical carcinomas and many other tumors, including many head and neck cancers. In these cancer cells, the HPV DNA genome is integrated into the cellular genome, where it expresses high levels of two viral oncogenes, called E6 and E7, that are required for cancer cell growth and viability. Here, we demonstrate that the recently described bacterial CRISPR/Cas RNA-guided endonuclease can be reprogrammed to target and destroy the E6 or E7 gene in cervical carcinoma cells transformed by HPV, resulting in cell cycle arrest, leading to cancer cell death. We propose that viral vectors designed to deliver E6- and/or E7-specific CRISPR/Cas to tumor cells could represent a novel and highly effective tool to treat and eliminate HPV-induced cancers.

Authors
Kennedy, EM; Kornepati, AVR; Goldstein, M; Bogerd, HP; Poling, BC; Whisnant, AW; Kastan, MB; Cullen, BR
MLA Citation
Kennedy, EM, Kornepati, AVR, Goldstein, M, Bogerd, HP, Poling, BC, Whisnant, AW, Kastan, MB, and Cullen, BR. "Inactivation of the human papillomavirus E6 or E7 gene in cervical carcinoma cells by using a bacterial CRISPR/Cas RNA-guided endonuclease." Journal of virology 88.20 (October 2014): 11965-11972.
PMID
25100830
Source
epmc
Published In
Journal of virology
Volume
88
Issue
20
Publish Date
2014
Start Page
11965
End Page
11972
DOI
10.1128/jvi.01879-14

Development of a cell-based, high-throughput screening assay for ATM kinase inhibitors.

The ATM (ataxia-telangiectasia, mutated) protein kinase is a major regulator of cellular responses to DNA double-strand breaks (DSBs), DNA lesions that can be caused by ionizing irradiation (IR), oxidative damage, or exposure to certain chemical agents. In response to DSBs, the ATM kinase is activated and subsequently phosphorylates numerous downstream substrates, including p53, Chk2, BRCA1, and KAP1, which affect processes such as cell cycle progression and DNA repair. Numerous studies have demonstrated that loss of ATM function results in enhanced sensitivity to ionizing irradiation in clinically relevant dose ranges, suggesting that ATM kinase is an attractive therapeutic target for enhancing tumor cell kill with radiotherapy. Previously identified small-molecule ATM kinase inhibitors, such as CP466722 and Ku55933, were identified using in vitro kinase assays carried out with recombinant ATM kinase isolated from mammalian cells. Since it has not been feasible to express full-length recombinant ATM in bacterial or baculovirus systems, a robust in vitro screening tool has been lacking. We have developed a cell-based assay that is robust, straightforward, and sensitive. Using this high-throughput assay, we screened more than 7000 compounds and discovered additional small molecules that inhibit the ATM kinase and further validated these hits by secondary assays.

Authors
Guo, K; Shelat, AA; Guy, RK; Kastan, MB
MLA Citation
Guo, K, Shelat, AA, Guy, RK, and Kastan, MB. "Development of a cell-based, high-throughput screening assay for ATM kinase inhibitors." Journal of biomolecular screening 19.4 (April 2014): 538-546.
PMID
24464432
Source
epmc
Published In
Journal of Biomolecular Screening
Volume
19
Issue
4
Publish Date
2014
Start Page
538
End Page
546
DOI
10.1177/1087057113520325

Rad17 recruits the MRE11-RAD50-NBS1 complex to regulate the cellular response to DNA double-strand breaks.

The MRE11-RAD50-NBS1 (MRN) complex is essential for the detection of DNA double-strand breaks (DSBs) and initiation of DNA damage signaling. Here, we show that Rad17, a replication checkpoint protein, is required for the early recruitment of the MRN complex to the DSB site that is independent of MDC1 and contributes to ATM activation. Mechanistically, Rad17 is phosphorylated by ATM at a novel Thr622 site resulting in a direct interaction of Rad17 with NBS1, facilitating recruitment of the MRN complex and ATM to the DSB, thereby enhancing ATM signaling. Repetition of these events creates a positive feedback for Rad17-dependent activation of MRN/ATM signaling which appears to be a requisite for the activation of MDC1-dependent MRN complex recruitment. A point mutation of the Thr622 residue of Rad17 leads to a significant reduction in MRN/ATM signaling and homologous recombination repair, suggesting that Thr622 phosphorylation is important for regulation of the MRN/ATM signaling by Rad17. These findings suggest that Rad17 plays a critical role in the cellular response to DNA damage via regulation of the MRN/ATM pathway.

Authors
Wang, Q; Goldstein, M; Alexander, P; Wakeman, TP; Sun, T; Feng, J; Lou, Z; Kastan, MB; Wang, X-F
MLA Citation
Wang, Q, Goldstein, M, Alexander, P, Wakeman, TP, Sun, T, Feng, J, Lou, Z, Kastan, MB, and Wang, X-F. "Rad17 recruits the MRE11-RAD50-NBS1 complex to regulate the cellular response to DNA double-strand breaks." The EMBO journal 33.8 (April 2014): 862-877.
PMID
24534091
Source
epmc
Published In
EMBO Journal
Volume
33
Issue
8
Publish Date
2014
Start Page
862
End Page
877
DOI
10.1002/embj.201386064

Pilot study of modified LMB-based therapy for children with ataxia-telangiectasia and advanced stage high grade mature B-cell malignancies.

Children with ataxia-telangiectasia (A-T) and cancer have a poorer prognosis due in part to increased treatment-related toxicity. We piloted a curative intent approach in five children with A-T who presented with advanced stage (III, n = 2; IV, n = 3) B-NHL (diffuse large B-cell lymphoma, n = 4; Burkitt leukemia, n = 1) using a modified LMB-based protocol. Two achieved sustained CCR (one, CCR at 6 years; one, pulmonary death after 3 years in CCR). Two died from toxicity during induction and 1 failed induction with progressive disease. Novel therapeutic approaches which overcome drug resistance and are less toxic are needed for children with A-T and B-NHL.

Authors
Sandlund, JT; Hudson, MM; Kennedy, W; Onciu, M; Kastan, MB
MLA Citation
Sandlund, JT, Hudson, MM, Kennedy, W, Onciu, M, and Kastan, MB. "Pilot study of modified LMB-based therapy for children with ataxia-telangiectasia and advanced stage high grade mature B-cell malignancies." Pediatr Blood Cancer 61.2 (February 2014): 360-362.
PMID
23900766
Source
pubmed
Published In
Pediatric Blood & Cancer
Volume
61
Issue
2
Publish Date
2014
Start Page
360
End Page
362
DOI
10.1002/pbc.24696

Inactivation of the human papillomavirus E6 or E7 gene in cervical carcinoma cells by using a bacterial CRISPR/Cas RNA-guided endonuclease

© 2014, American Society for Microbiology.High-risk human papillomaviruses (HPVs), including HPV-16 and HPV-18, are the causative agents of cervical carcinomas and are linked to several other tumors of the anogenital and oropharyngeal regions. The majority of HPV-induced tumors contain integrated copies of the normally episomal HPV genome that invariably retain intact forms of the two HPV oncogenes E6 and E7. E6 induces degradation of the cellular tumor suppressor p53, while E7 destabilizes the retinoblastoma (Rb) protein. Previous work has shown that loss of E6 function in cervical cancer cells induces p53 expression as well as downstream effectors that induce apoptosis and cell cycle arrest. Similarly, loss of E7 allows increased Rb expression, leading to cell cycle arrest and senescence. Here, we demonstrate that expression of a bacterial Cas9 RNA-guided endonuclease, together with single guide RNAs (sgRNAs) specific for E6 or E7, is able to induce cleavage of the HPV genome, resulting in the introduction of inactivating deletion and insertion mutations into the E6 or E7 gene. This results in the induction of p53 or Rb, leading to cell cycle arrest and eventual cell death. Both HPV-16- and HPV-18-transformed cells were found to be responsive to targeted HPV genome-specific DNA cleavage. These data provide a proof of principle for the idea that vector-delivered Cas9/sgRNA combinations could represent effective treatment modalities for HPV-induced cancers.

Authors
Kennedy, EM; Kornepati, AVR; Goldstein, M; Bogerd, HP; Poling, BC; Whisnant, AW; Kastan, MB; Cullen, BR
MLA Citation
Kennedy, EM, Kornepati, AVR, Goldstein, M, Bogerd, HP, Poling, BC, Whisnant, AW, Kastan, MB, and Cullen, BR. "Inactivation of the human papillomavirus E6 or E7 gene in cervical carcinoma cells by using a bacterial CRISPR/Cas RNA-guided endonuclease." Journal of Virology 88.20 (January 1, 2014): 11965-11972.
Source
scopus
Published In
Journal of virology
Volume
88
Issue
20
Publish Date
2014
Start Page
11965
End Page
11972
DOI
10.1128/JVI.01879-14

Erratum: Development of a cell-based, high-throughput screening assay for atm kinase inhibitors (Journal of Biomolecular Screening (2014) 19:4 (538-546) DOI:10.1177/1087057113520325)

Authors
Guo, K; Anang, A; Shelat, R; Guy, K; Kastan, MB
MLA Citation
Guo, K, Anang, A, Shelat, R, Guy, K, and Kastan, MB. "Erratum: Development of a cell-based, high-throughput screening assay for atm kinase inhibitors (Journal of Biomolecular Screening (2014) 19:4 (538-546) DOI:10.1177/1087057113520325)." Journal of Biomolecular Screening 19.10 (January 1, 2014): 1418-.
Source
scopus
Published In
Journal of Biomolecular Screening
Volume
19
Issue
10
Publish Date
2014
Start Page
1418
DOI
10.1177/1087057114559509

DNA Damage Response Pathways and Cancer

Authors
Ford, JM; Kastan, MB
MLA Citation
Ford, JM, and Kastan, MB. "DNA Damage Response Pathways and Cancer." Abeloff's Clinical Oncology: Fifth Edition. October 22, 2013. 142-153.e4.
Source
scopus
Publish Date
2013
Start Page
142
End Page
153.e4
DOI
10.1016/B978-1-4557-2865-7.00010-2

Abeloff's Clinical Oncology: Fifth Edition

© 2014 by Saunders. All rights reserved.Practical and clinically focused, Abeloff's Clinical Oncology is a trusted medical reference book designed to capture the latest scientific discoveries and their implications for cancer diagnosis and management of cancer in the most accessible manner possible. Abeloff's equips everyone involved - from radiologists and oncologists to surgeons and nurses - to collaborate effectively and provide the best possible cancer care.

Authors
Niederhuber, JE; Armitage, JO; Doroshow, JH; Kastan, MB; Tepper, JE
MLA Citation
Niederhuber, JE, Armitage, JO, Doroshow, JH, Kastan, MB, and Tepper, JE. Abeloff's Clinical Oncology: Fifth Edition. October 22, 2013.
Source
scopus
Publish Date
2013
Start Page
1
End Page
2186

Preface

Authors
Niederhuber, JE; Armitage, JO; Doroshow, JH; Kastan, MB; Tepper, JE
MLA Citation
Niederhuber, JE, Armitage, JO, Doroshow, JH, Kastan, MB, and Tepper, JE. Preface. October 22, 2013.
Source
scopus
Publish Date
2013
Start Page
ix
DOI
10.1016/B978-1-4557-2865-7.00114-4

Nucleolin mediates nucleosome disruption critical for DNA double-strand break repair.

Recruitment of DNA repair factors and modulation of chromatin structure at sites of DNA double-strand breaks (DSBs) is a complex and highly orchestrated process. We developed a system that can induce DSBs rapidly at defined endogenous sites in mammalian genomes and enables direct assessment of repair and monitoring of protein recruitment, egress, and modification at DSBs. The tight regulation of the system also permits assessments of relative kinetics and dependencies of events associated with cellular responses to DNA breakage. Distinct advantages of this system over focus formation/disappearance assays for assessing DSB repair are demonstrated. Using ChIP, we found that nucleosomes are partially disassembled around DSBs during nonhomologous end-joining repair in G1-arrested mammalian cells, characterized by a transient loss of the H2A/H2B histone dimer. Nucleolin, a protein with histone chaperone activity, interacts with RAD50 via its arginine-glycine rich domain and is recruited to DSBs rapidly in an MRE11-NBS1-RAD50 complex-dependent manner. Down-regulation of nucleolin abrogates the nucleosome disruption, the recruitment of repair factors, and the repair of the DSB, demonstrating the functional importance of nucleosome disruption in DSB repair and identifying a chromatin-remodeling protein required for the process. Interestingly, the nucleosome disruption that occurs during DSB repair in cycling cells differs in that both H2A/H2B and H3/H4 histone dimers are removed. This complete nucleosome disruption is also dependent on nucleolin and is required for recruitment of replication protein A to DSBs, a marker of DSB processing that is a requisite for homologous recombination repair.

Authors
Goldstein, M; Derheimer, FA; Tait-Mulder, J; Kastan, MB
MLA Citation
Goldstein, M, Derheimer, FA, Tait-Mulder, J, and Kastan, MB. "Nucleolin mediates nucleosome disruption critical for DNA double-strand break repair." Proc Natl Acad Sci U S A 110.42 (October 15, 2013): 16874-16879.
PMID
24082117
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
110
Issue
42
Publish Date
2013
Start Page
16874
End Page
16879
DOI
10.1073/pnas.1306160110

A tuberous sclerosis complex signalling node at the peroxisome regulates mTORC1 and autophagy in response to ROS.

Subcellular localization is emerging as an important mechanism for mTORC1 regulation. We report that the tuberous sclerosis complex (TSC) signalling node, TSC1, TSC2 and Rheb, localizes to peroxisomes, where it regulates mTORC1 in response to reactive oxygen species (ROS). TSC1 and TSC2 were bound by peroxisomal biogenesis factors 19 and 5 (PEX19 and PEX5), respectively, and peroxisome-localized TSC functioned as a Rheb GTPase-activating protein (GAP) to suppress mTORC1 and induce autophagy. Naturally occurring pathogenic mutations in TSC2 decreased PEX5 binding, and abrogated peroxisome localization, Rheb GAP activity and suppression of mTORC1 by ROS. Cells lacking peroxisomes were deficient in mTORC1 repression by ROS, and peroxisome-localization-deficient TSC2 mutants caused polarity defects and formation of multiple axons in neurons. These data identify a role for the TSC in responding to ROS at the peroxisome, and identify the peroxisome as a signalling organelle involved in regulation of mTORC1.

Authors
Zhang, J; Kim, J; Alexander, A; Cai, S; Tripathi, DN; Dere, R; Tee, AR; Tait-Mulder, J; Di Nardo, A; Han, JM; Kwiatkowski, E; Dunlop, EA; Dodd, KM; Folkerth, RD; Faust, PL; Kastan, MB; Sahin, M; Walker, CL
MLA Citation
Zhang, J, Kim, J, Alexander, A, Cai, S, Tripathi, DN, Dere, R, Tee, AR, Tait-Mulder, J, Di Nardo, A, Han, JM, Kwiatkowski, E, Dunlop, EA, Dodd, KM, Folkerth, RD, Faust, PL, Kastan, MB, Sahin, M, and Walker, CL. "A tuberous sclerosis complex signalling node at the peroxisome regulates mTORC1 and autophagy in response to ROS." Nat Cell Biol 15.10 (October 2013): 1186-1196.
PMID
23955302
Source
pubmed
Published In
Nature Cell Biology
Volume
15
Issue
10
Publish Date
2013
Start Page
1186
End Page
1196
DOI
10.1038/ncb2822

Strategies for optimizing the response of cancer and normal tissues to radiation.

Approximately 50% of all patients with cancer receive radiation therapy at some point during the course of their treatment, and the majority of these patients are treated with curative intent. Despite recent advances in the planning of radiation treatment and the delivery of image-guided radiation therapy, acute toxicity and potential long-term side effects often limit the ability to deliver a sufficient dose of radiation to control tumours locally. In the past two decades, a better understanding of the hallmarks of cancer and the discovery of specific signalling pathways by which cells respond to radiation have provided new opportunities to design molecularly targeted therapies to increase the therapeutic window of radiation therapy. Here, we review efforts to develop approaches that could improve outcomes with radiation therapy by increasing the probability of tumour cure or by decreasing normal tissue toxicity.

Authors
Moding, EJ; Kastan, MB; Kirsch, DG
MLA Citation
Moding, EJ, Kastan, MB, and Kirsch, DG. "Strategies for optimizing the response of cancer and normal tissues to radiation." Nat Rev Drug Discov 12.7 (July 2013): 526-542. (Review)
PMID
23812271
Source
pubmed
Published In
Nature Reviews Drug Discovery
Volume
12
Issue
7
Publish Date
2013
Start Page
526
End Page
542
DOI
10.1038/nrd4003

A tuberous sclerosis complex signalling node at the peroxisome regulates mTORC1 and autophagy in response to ROS

Subcellular localization is emerging as an important mechanism for mTORC1 regulation. We report that the tuberous sclerosis complex (TSC) signalling node, TSC1, TSC2 and Rheb, localizes to peroxisomes, where it regulates mTORC1 in response to reactive oxygen species (ROS). TSC1 and TSC2 were bound by peroxisomal biogenesis factors 19 and 5 (PEX19 and PEX5), respectively, and peroxisome-localized TSC functioned as a Rheb GTPase-activating protein (GAP) to suppress mTORC1 and induce autophagy. Naturally occurring pathogenic mutations in TSC2 decreased PEX5 binding, and abrogated peroxisome localization, Rheb GAP activity and suppression of mTORC1 by ROS. Cells lacking peroxisomes were deficient in mTORC1 repression by ROS, and peroxisome-localization-deficient TSC2 mutants caused polarity defects and formation of multiple axons in neurons. These data identify a role for the TSC in responding to ROS at the peroxisome, and identify the peroxisome as a signalling organelle involved in regulation of mTORC1. © 2013 Macmillan Publishers Limited. All rights reserved.

Authors
Zhang, J; Kim, J; Alexander, A; Cai, S; Tripathi, DN; Dere, R; Tee, AR; Tait-Mulder, J; Nardo, AD; Han, JM; Kwiatkowski, E; Dunlop, EA; Dodd, KM; Folkerth, RD; Faust, PL; Kastan, MB; Sahin, M; Walker, CL
MLA Citation
Zhang, J, Kim, J, Alexander, A, Cai, S, Tripathi, DN, Dere, R, Tee, AR, Tait-Mulder, J, Nardo, AD, Han, JM, Kwiatkowski, E, Dunlop, EA, Dodd, KM, Folkerth, RD, Faust, PL, Kastan, MB, Sahin, M, and Walker, CL. "A tuberous sclerosis complex signalling node at the peroxisome regulates mTORC1 and autophagy in response to ROS." Nature Cell Biology 15.10 (2013): 1186-1196.
Source
scival
Published In
Nature Cell Biology
Volume
15
Issue
10
Publish Date
2013
Start Page
1186
End Page
1196
DOI
10.1038/ncb2822

A message from the Editor-in-Chief.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "A message from the Editor-in-Chief." Mol Cancer Res 10.12 (December 2012): 1513-.
PMID
23193157
Source
pubmed
Published In
Molecular cancer research : MCR
Volume
10
Issue
12
Publish Date
2012
Start Page
1513
DOI
10.1158/1541-7786.MCR-12-0644

Chloroquine improves survival and hematopoietic recovery after lethal low-dose-rate radiation.

PURPOSE: We have previously shown that the antimalarial agent chloroquine can abrogate the lethal cellular effects of low-dose-rate (LDR) radiation in vitro, most likely by activating the ataxia-telangiectasia mutated (ATM) protein. Here, we demonstrate that chloroquine treatment also protects against lethal doses of LDR radiation in vivo. METHODS AND MATERIALS: C57BL/6 mice were irradiated with a total of 12.8 Gy delivered at 9.4 cGy/hour. ATM null mice from the same background were used to determine the influence of ATM. Chloroquine was administered by two intraperitoneal injections of 59.4 μg per 17 g of body weight, 24 hours and 4 hours before irradiation. Bone marrow cells isolated from tibia, fibula, and vertebral bones were transplanted into lethally irradiated CD45 congenic recipient mice by retroorbital injection. Chimerism was assessed by flow cytometry. In vitro methylcellulose colony-forming assay of whole bone marrow cells and fluorescence activated cell sorting analysis of lineage depleted cells were used to assess the effect of chloroquine on progenitor cells. RESULTS: Mice pretreated with chloroquine before radiation exhibited a significantly higher survival rate than did mice treated with radiation alone (80% vs. 31%, p = 0.0026). Chloroquine administration before radiation did not affect the survival of ATM null mice (p = 0.86). Chloroquine also had a significant effect on the early engraftment of bone marrow cells from the irradiated donor mice 6 weeks after transplantation (4.2% vs. 0.4%, p = 0.015). CONCLUSION: Chloroquine administration before radiation had a significant effect on the survival of normal but not ATM null mice, strongly suggesting that the in vivo effect, like the in vitro effect, is also ATM dependent. Chloroquine improved the early engraftment of bone marrow cells from LDR-irradiated mice, presumably by protecting the progenitor cells from radiation injury. Chloroquine thus could serve as a very useful drug for protection against the harmful effects of LDR radiation.

Authors
Lim, Y; Hedayati, M; Merchant, AA; Zhang, Y; Yu, H-HM; Kastan, MB; Matsui, W; Deweese, TL
MLA Citation
Lim, Y, Hedayati, M, Merchant, AA, Zhang, Y, Yu, H-HM, Kastan, MB, Matsui, W, and Deweese, TL. "Chloroquine improves survival and hematopoietic recovery after lethal low-dose-rate radiation." Int J Radiat Oncol Biol Phys 84.3 (November 1, 2012): 800-806.
PMID
22445004
Source
pubmed
Published In
International Journal of Radiation: Oncology - Biology - Physics
Volume
84
Issue
3
Publish Date
2012
Start Page
800
End Page
806
DOI
10.1016/j.ijrobp.2012.01.026

Interactions of nucleolin and ribosomal protein L26 (RPL26) in translational control of human p53 mRNA.

Ribosomal protein RPL26 enhances p53 translation after DNA damage, and this regulation depends upon interactions between the 5'- and 3'-UTRs of human p53 mRNA (Takagi, M., Absalon, M. J., McLure, K. G., and Kastan, M. B. (2005) Cell 123, 49-63; Chen, J., and Kastan, M. B. (2010) Genes Dev. 24, 2146-2156). In contrast, nucleolin (NCL) suppresses the translation of p53 mRNA and its induction after DNA damage. We confirmed reports that RPL26 and NCL interact with each other and then explored the potential role of this interaction in the translational control of p53 after stress. NCL repression of p53 translation utilizes both the 5'- and 3'-UTRs of p53 mRNA, and NCL binds to the same 5'-3'-UTR interaction region that is critical for the recruitment of RPL26 to p53 mRNA after DNA damage. We also found that NCL is able to oligomerize, consistent with a model in which NCL stabilizes this double-stranded RNA structure. We found that the RNA-binding domain of NCL participates in binding to p53 mRNA, is required for both NCL dimerization and NCL-mediated translational repression, and is the domain of NCL that interacts with RPL26. Excessive RPL26 disrupts NCL dimerization, and point mutations in the NCL-interacting region of RPL26 reduce NCL-RPL26 interactions and attenuate both RPL26 binding to human p53 mRNA and p53 induction by RPL26. These observations suggest a model in which the base pairings in the p53 UTR interaction regions are critical for both translational repression and stress induction of p53 by NCL and RPL26, respectively, and that disruption of a NCL-NCL homodimer by RPL26 may be the switch between translational repression and activation after stress.

Authors
Chen, J; Guo, K; Kastan, MB
MLA Citation
Chen, J, Guo, K, and Kastan, MB. "Interactions of nucleolin and ribosomal protein L26 (RPL26) in translational control of human p53 mRNA." J Biol Chem 287.20 (May 11, 2012): 16467-16476.
PMID
22433872
Source
pubmed
Published In
The Journal of biological chemistry
Volume
287
Issue
20
Publish Date
2012
Start Page
16467
End Page
16476
DOI
10.1074/jbc.M112.349274

A new role for ATM: regulating mitochondrial function and mitophagy.

The various pathologies in ataxia telangiectasia (A-T) patients including T-cell lymphomagenesis have been attributed to defects in the DNA damage response pathway because ATM, the gene mutated in this disease, is a key mediator of this process. Analysis of Atm-deficient thymocytes in mice reveals that the absence of this gene results in altered mitochondrial homeostasis, a phenomenon that appears to result from abnormal mitophagy engagement. Interestingly, allelic loss of the autophagic gene Becn1 delays tumorigenesis in Atm-null mice presumably by reversing the mitochondrial abnormalities and not by improving the DNA damage response (DDR) pathway. Thus, ATM plays a critical role in modulating mitochondrial homeostasis perhaps by regulating mitophagy.

Authors
Valentin-Vega, YA; Kastan, MB
MLA Citation
Valentin-Vega, YA, and Kastan, MB. "A new role for ATM: regulating mitochondrial function and mitophagy." Autophagy 8.5 (May 1, 2012): 840-841.
PMID
22617444
Source
pubmed
Published In
Autophagy
Volume
8
Issue
5
Publish Date
2012
Start Page
840
End Page
841
DOI
10.4161/auto.19693

Autophagy links inflammasomes to atherosclerotic progression.

We investigated the role of autophagy in atherosclerosis. During plaque formation in mice, autophagic markers colocalized predominantly with macrophages (mφ). Atherosclerotic aortas had elevated levels of p62, suggesting that dysfunctional autophagy is characteristic of plaques. To determine whether autophagy directly influences atherogenesis, we characterized Beclin-1 heterozygous-null and mφ-specific ATG5-null (ATG5-mφKO) mice, commonly used models of autophagy haploinsufficiency and deficiency, respectively. Haploinsufficent Beclin-1 mice had no atherosclerotic phenotype, but ATG5-mφKO mice had increased plaques, suggesting an essential role for basal levels of autophagy in atheroprotection. Defective autophagy is associated with proatherogenic inflammasome activation. Classic inflammasome markers were robustly induced in ATG5-null mφ, especially when coincubated with cholesterol crystals. Moreover, cholesterol crystals appear to be increased in ATG5-mφKO plaques, suggesting a potentially vicious cycle of crystal formation and inflammasome activation in autophagy-deficient plaques. These results show that autophagy becomes dysfunctional in atherosclerosis and its deficiency promotes atherosclerosis in part through inflammasome hyperactivation.

Authors
Razani, B; Feng, C; Coleman, T; Emanuel, R; Wen, H; Hwang, S; Ting, JP; Virgin, HW; Kastan, MB; Semenkovich, CF
MLA Citation
Razani, B, Feng, C, Coleman, T, Emanuel, R, Wen, H, Hwang, S, Ting, JP, Virgin, HW, Kastan, MB, and Semenkovich, CF. "Autophagy links inflammasomes to atherosclerotic progression." Cell Metab 15.4 (April 4, 2012): 534-544.
PMID
22440612
Source
pubmed
Published In
Cell Metabolism
Volume
15
Issue
4
Publish Date
2012
Start Page
534
End Page
544
DOI
10.1016/j.cmet.2012.02.011

Optimizing ATM inhibitor activity and specificity using pharmacophore-based docking

Authors
Bharatham, K; Suryadevara, PK; Guo, K; Min, J; Kastan, MB; Guy, RK; Shelat, A
MLA Citation
Bharatham, K, Suryadevara, PK, Guo, K, Min, J, Kastan, MB, Guy, RK, and Shelat, A. "Optimizing ATM inhibitor activity and specificity using pharmacophore-based docking." March 25, 2012.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
243
Publish Date
2012

Mitochondrial dysfunction in ataxia-telangiectasia.

Ataxia-telangiectasia mutated (ATM) plays a central role in DNA damage responses, and its loss leads to development of T-cell malignancies. Here, we show that ATM loss also leads to intrinsic mitochondrial abnormalities in thymocytes, including elevated reactive oxygen species, increased aberrant mitochondria, high cellular respiratory capacity, and decreased mitophagy. A fraction of ATM protein is localized in mitochondria, and it is rapidly activated by mitochondrial dysfunction. Unexpectedly, allelic loss of the autophagy regulator Beclin-1 significantly delayed tumor development in ATM-null mice. This effect was not associated with rescue of DNA damage signaling but rather with a significant reversal of the mitochondrial abnormalities. These data support a model in which ATM plays direct roles in modulating mitochondrial homeostasis and suggest that mitochondrial dysfunction and associated increases in mitochondrial reactive oxygen species contribute to the cancer-prone phenotype observed in organisms lacking ATM. Thus, ataxia-telangiectasia should be considered, at least in part, as a mitochondrial disease.

Authors
Valentin-Vega, YA; Maclean, KH; Tait-Mulder, J; Milasta, S; Steeves, M; Dorsey, FC; Cleveland, JL; Green, DR; Kastan, MB
MLA Citation
Valentin-Vega, YA, Maclean, KH, Tait-Mulder, J, Milasta, S, Steeves, M, Dorsey, FC, Cleveland, JL, Green, DR, and Kastan, MB. "Mitochondrial dysfunction in ataxia-telangiectasia." Blood 119.6 (February 9, 2012): 1490-1500.
PMID
22144182
Source
pubmed
Published In
Blood
Volume
119
Issue
6
Publish Date
2012
Start Page
1490
End Page
1500
DOI
10.1182/blood-2011-08-373639

A new role for ATM

Authors
Valentin-Vega, YA; Kastan, MB
MLA Citation
Valentin-Vega, YA, and Kastan, MB. "A new role for ATM." AUTOPHAGY 8.5 (2012): 840-841.
Source
wos-lite
Published In
Autophagy
Volume
8
Issue
5
Publish Date
2012
Start Page
840
End Page
841
DOI
10.4161/auto.19693

ATM signals to TSC2 in the cytoplasm to regulate mTORC1 in response to ROS (Proceedings of the National Academy of Sciences (2010) 107 (4153-4158) DOI: 10.1073/pnas.0913860107)

Authors
Alexander, A; Cai, S-L; Kim, J; Nanez, A; Sahin, M; MacLean, KH; Inoki, K; Guan, K-L; Shen, J; Person, MD; Kusewitt, D; Mills, GB; Kastan, MB; Walker, CL
MLA Citation
Alexander, A, Cai, S-L, Kim, J, Nanez, A, Sahin, M, MacLean, KH, Inoki, K, Guan, K-L, Shen, J, Person, MD, Kusewitt, D, Mills, GB, Kastan, MB, and Walker, CL. "ATM signals to TSC2 in the cytoplasm to regulate mTORC1 in response to ROS (Proceedings of the National Academy of Sciences (2010) 107 (4153-4158) DOI: 10.1073/pnas.0913860107)." Proceedings of the National Academy of Sciences of the United States of America 109.21 (2012): 8352--.
Source
scival
Published In
Proceedings of the National Academy of Sciences of USA
Volume
109
Issue
21
Publish Date
2012
Start Page
8352-
DOI
10.1073/pnas.1206201109

Abstract 3086: Interactions of nucleolin and ribosomal protein RPL26 in the translational control of human p53 mRNA

Authors
Chen, J; Guo, K; Kastan, MB
MLA Citation
Chen, J, Guo, K, and Kastan, MB. "Abstract 3086: Interactions of nucleolin and ribosomal protein RPL26 in the translational control of human p53 mRNA." Cancer Research 71.8 Supplement (April 15, 2011): 3086-3086.
Source
crossref
Published In
Cancer Research
Volume
71
Issue
8 Supplement
Publish Date
2011
Start Page
3086
End Page
3086
DOI
10.1158/1538-7445.AM2011-3086

Chloroquine Activates ATM and Improves Hematopoietic Recovery and Survival of Mice following Low Dose-rate Radiation

Authors
DeWeese, TL; Lim, Y; Hedayati, M; Merchant, A; Zhang, Y; Yu, HM; Kastan, MB; Matsui, W
MLA Citation
DeWeese, TL, Lim, Y, Hedayati, M, Merchant, A, Zhang, Y, Yu, HM, Kastan, MB, and Matsui, W. "Chloroquine Activates ATM and Improves Hematopoietic Recovery and Survival of Mice following Low Dose-rate Radiation." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 81.2 (2011): S191-S192.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
81
Issue
2
Publish Date
2011
Start Page
S191
End Page
S192

5'-3'-UTR interactions regulate p53 mRNA translation and provide a target for modulating p53 induction after DNA damage.

Optimal induction of p53 protein after DNA damage requires RPL26-mediated increases in p53 mRNA translation. We report here the existence of a dsRNA region containing complementary sequences of the 5'- and 3'-untranslated regions (UTRs) of human p53 mRNA that is critical for its translational regulation by RPL26. Mutating as few as 3 bases in either of the two complementary UTR sequences abrogates the ability of RPL26 to bind to p53 mRNA and stimulate p53 translation, while compensatory mutations restore this binding and regulation. Short, single-strand oligonucleotides that target this 5'-3'-UTR base-pairing region blunt the binding of RPL26 to p53 mRNA in cells and reduce p53 induction and p53-mediated cell death after several different types of DNA damage and cellular stress. The ability to reduce stress induction of p53 with oligonucleotides or other small molecules has numerous potential therapeutic uses.

Authors
Chen, J; Kastan, MB
MLA Citation
Chen, J, and Kastan, MB. "5'-3'-UTR interactions regulate p53 mRNA translation and provide a target for modulating p53 induction after DNA damage." Genes Dev 24.19 (October 1, 2010): 2146-2156.
PMID
20837656
Source
pubmed
Published In
Genes & development
Volume
24
Issue
19
Publish Date
2010
Start Page
2146
End Page
2156
DOI
10.1101/gad.1968910

Multiple roles of ATM in monitoring and maintaining DNA integrity.

The ability of our cells to maintain genomic integrity is fundamental for protection from cancer development. Central to this process is the ability of cells to recognize and repair DNA damage and progress through the cell cycle in a regulated and orderly manner. In addition, protection of chromosome ends through the proper assembly of telomeres prevents loss of genetic information and aberrant chromosome fusions. Cells derived from patients with ataxia-telangiectasia (A-T) show defects in cell cycle regulation, abnormal responses to DNA breakage, and chromosomal end-to-end fusions. The identification and characterization of the ATM (ataxia-telangiectasia, mutated) gene product has provided an essential tool for researchers in elucidating cellular mechanisms involved in cell cycle control, DNA repair, and chromosomal stability.

Authors
Derheimer, FA; Kastan, MB
MLA Citation
Derheimer, FA, and Kastan, MB. "Multiple roles of ATM in monitoring and maintaining DNA integrity." FEBS Lett 584.17 (September 10, 2010): 3675-3681. (Review)
PMID
20580718
Source
pubmed
Published In
FEBS Letters
Volume
584
Issue
17
Publish Date
2010
Start Page
3675
End Page
3681
DOI
10.1016/j.febslet.2010.05.031

Deficient innate immunity, thymopoiesis, and gene expression response to radiation in survivors of childhood acute lymphoblastic leukemia.

BACKGROUND: Survivors of childhood acute lymphoblastic leukemia (ALL) are at an increased risk of developing secondary malignant neoplasms. Radiation and chemotherapy can cause mutations and cytogenetic abnormalities and induce genomic instability. Host immunity and appropriate DNA damage responses are critical inhibitors of carcinogenesis. Therefore, we sought to determine the long-term effects of ALL treatment on immune function and response to DNA damage. METHODS: Comparative studies on 14 survivors in first complete remission and 16 siblings were conducted. RESULTS: In comparison to siblings on the cells that were involved in adaptive immunity, the patients had either higher numbers (CD19+ B cells and CD4+CD25+ T regulatory cells) or similar numbers (alphabetaT cells and CD45RO+/RA- memory T cells) in the blood. In contrast, patients had lower numbers of all lymphocyte subsets involved in innate immunity (gammadeltaT cells and all NK subsets, including KIR2DL1+ cells, KIR2DL2/L3+ cells, and CD16+ cells), and lower natural cytotoxicity against K562 leukemia cells. Thymopoiesis was lower in patients, as demonstrated by less CD45RO-/RA+ naïve T cell and less SjTREC levels in the blood, whereas the Vbeta spectratype complexity score was similar. Array of gene expression response to low-dose radiation showed that about 70% of the probesets had a reduced response in patients. One of these genes, SCHIP-1, was also among the top-ranked single nucleotide polymorphisms (SNPs) during the whole-genome scanning by SNP microarray analysis. CONCLUSION: ALL survivors were deficient in innate immunity, thymopoiesis, and DNA damage responses to radiation. These defects may contribute to their increased likelihood of second malignancy.

Authors
Leung, W; Neale, G; Behm, F; Iyengar, R; Finkelstein, D; Kastan, MB; Pui, C-H
MLA Citation
Leung, W, Neale, G, Behm, F, Iyengar, R, Finkelstein, D, Kastan, MB, and Pui, C-H. "Deficient innate immunity, thymopoiesis, and gene expression response to radiation in survivors of childhood acute lymphoblastic leukemia." Cancer Epidemiol 34.3 (June 2010): 303-308.
PMID
20413363
Source
pubmed
Published In
Cancer Epidemiology
Volume
34
Issue
3
Publish Date
2010
Start Page
303
End Page
308
DOI
10.1016/j.canep.2010.03.008

RADIATION THERAPY AND ADJUVANT CHEMOTHERAPY IN A PATIENT WITH A HIGH GRADE GLIOMA AND UNDERLYING ATAXIA TELANGIECTASIA

Authors
DeWire, MD; Pananandiker, ASP; Ellison, DE; McKinnon, PJ; Kastan, MB; Gajjar, A
MLA Citation
DeWire, MD, Pananandiker, ASP, Ellison, DE, McKinnon, PJ, Kastan, MB, and Gajjar, A. "RADIATION THERAPY AND ADJUVANT CHEMOTHERAPY IN A PATIENT WITH A HIGH GRADE GLIOMA AND UNDERLYING ATAXIA TELANGIECTASIA." June 2010.
Source
wos-lite
Published In
Neuro-Oncology
Volume
12
Issue
6
Publish Date
2010
Start Page
II87
End Page
II87

Abstract 4831: ATM signals to TSC2 in the cytoplasm to regulate mTORC1 and autophagy in response to ROS

Authors
Alexander, A; Cai, S-L; Kim, J; Nanez, A; Sahin, M; MacLean, KH; Inoki, K; Guan, K-L; Shen, J; Person, MD; Kusewitt, D; Mills, GB; Kastan, MB; Walker, CL
MLA Citation
Alexander, A, Cai, S-L, Kim, J, Nanez, A, Sahin, M, MacLean, KH, Inoki, K, Guan, K-L, Shen, J, Person, MD, Kusewitt, D, Mills, GB, Kastan, MB, and Walker, CL. "Abstract 4831: ATM signals to TSC2 in the cytoplasm to regulate mTORC1 and autophagy in response to ROS." Cancer Research 70.8 Supplement (April 15, 2010): 4831-4831.
Source
crossref
Published In
Cancer Research
Volume
70
Issue
8 Supplement
Publish Date
2010
Start Page
4831
End Page
4831
DOI
10.1158/1538-7445.AM10-4831

The NLRP3 inflammasome protects against loss of epithelial integrity and mortality during experimental colitis.

Decreased expression of the Nlrp3 protein is associated with susceptibility to Crohn's disease. However, the role of Nlrp3 in colitis has not been characterized. Nlrp3 interacts with the adaptor protein ASC to activate caspase-1 in inflammasomes, which are protein complexes responsible for the maturation and secretion of interleukin-1beta (IL-1beta) and IL-18. Here, we showed that mice deficient for Nlrp3 or ASC and caspase-1 were highly susceptible to dextran sodium sulfate (DSS)-induced colitis. Defective inflammasome activation led to loss of epithelial integrity, resulting in systemic dispersion of commensal bacteria, massive leukocyte infiltration, and increased chemokine production in the colon. This process was a consequence of a decrease in IL-18 in mice lacking components of the Nlrp3 inflammasome, resulting in higher mortality rates. Thus, the Nlrp3 inflammasome is critically involved in the maintenance of intestinal homeostasis and protection against colitis.

Authors
Zaki, MH; Boyd, KL; Vogel, P; Kastan, MB; Lamkanfi, M; Kanneganti, T-D
MLA Citation
Zaki, MH, Boyd, KL, Vogel, P, Kastan, MB, Lamkanfi, M, and Kanneganti, T-D. "The NLRP3 inflammasome protects against loss of epithelial integrity and mortality during experimental colitis." Immunity 32.3 (March 26, 2010): 379-391.
PMID
20303296
Source
pubmed
Published In
Immunity
Volume
32
Issue
3
Publish Date
2010
Start Page
379
End Page
391
DOI
10.1016/j.immuni.2010.03.003

ATM signals to TSC2 in the cytoplasm to regulate mTORC1 in response to ROS.

Ataxia-telangiectasia mutated (ATM) is a cellular damage sensor that coordinates the cell cycle with damage-response checkpoints and DNA repair to preserve genomic integrity. However, ATM also has been implicated in metabolic regulation, and ATM deficiency is associated with elevated reactive oxygen species (ROS). ROS has a central role in many physiological and pathophysiological processes including inflammation and chronic diseases such as atherosclerosis and cancer, underscoring the importance of cellular pathways involved in redox homeostasis. We have identified a cytoplasmic function for ATM that participates in the cellular damage response to ROS. We show that in response to elevated ROS, ATM activates the TSC2 tumor suppressor via the LKB1/AMPK metabolic pathway in the cytoplasm to repress mTORC1 and induce autophagy. Importantly, elevated ROS and dysregulation of mTORC1 in ATM-deficient cells is inhibited by rapamycin, which also rescues lymphomagenesis in Atm-deficient mice. Our results identify a cytoplasmic pathway for ROS-induced ATM activation of TSC2 to regulate mTORC1 signaling and autophagy, identifying an integration node for the cellular damage response with key pathways involved in metabolism, protein synthesis, and cell survival.

Authors
Alexander, A; Cai, S-L; Kim, J; Nanez, A; Sahin, M; MacLean, KH; Inoki, K; Guan, K-L; Shen, J; Person, MD; Kusewitt, D; Mills, GB; Kastan, MB; Walker, CL
MLA Citation
Alexander, A, Cai, S-L, Kim, J, Nanez, A, Sahin, M, MacLean, KH, Inoki, K, Guan, K-L, Shen, J, Person, MD, Kusewitt, D, Mills, GB, Kastan, MB, and Walker, CL. "ATM signals to TSC2 in the cytoplasm to regulate mTORC1 in response to ROS." Proc Natl Acad Sci U S A 107.9 (March 2, 2010): 4153-4158.
PMID
20160076
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
107
Issue
9
Publish Date
2010
Start Page
4153
End Page
4158
DOI
10.1073/pnas.0913860107

Mdm2 regulates p53 mRNA translation through inhibitory interactions with ribosomal protein L26.

Mdm2 regulates the p53 tumor suppressor by promoting its proteasome-mediated degradation. Mdm2 and p53 engage in an autoregulatory feedback loop that maintains low p53 activity in nonstressed cells. We now report that Mdm2 regulates p53 levels also by targeting ribosomal protein L26. L26 binds p53 mRNA and augments its translation. Mdm2 binds L26 and drives its polyubiquitylation and proteasomal degradation. In addition, the binding of Mdm2 to L26 attenuates the association of L26 with p53 mRNA and represses L26-mediated augmentation of p53 protein synthesis. Under nonstressed conditions, both mechanisms help maintain low cellular p53 levels by constitutively tuning down p53 translation. In response to genotoxic stress, the inhibitory effect of Mdm2 on L26 is attenuated, enabling a rapid increase in p53 synthesis. The Mdm2-L26 interaction thus represents an additional important component of the autoregulatory feedback loop that dictates cellular p53 levels and activity.

Authors
Ofir-Rosenfeld, Y; Boggs, K; Michael, D; Kastan, MB; Oren, M
MLA Citation
Ofir-Rosenfeld, Y, Boggs, K, Michael, D, Kastan, MB, and Oren, M. "Mdm2 regulates p53 mRNA translation through inhibitory interactions with ribosomal protein L26." Mol Cell 32.2 (October 24, 2008): 180-189.
PMID
18951086
Source
pubmed
Published In
Molecular Cell
Volume
32
Issue
2
Publish Date
2008
Start Page
180
End Page
189
DOI
10.1016/j.molcel.2008.08.031

Transient inhibition of ATM kinase is sufficient to enhance cellular sensitivity to ionizing radiation.

In response to DNA damage, the ATM protein kinase activates signal transduction pathways essential for coordinating cell cycle progression with DNA repair. In the human disease ataxia-telangiectasia, mutation of the ATM gene results in multiple cellular defects, including enhanced sensitivity to ionizing radiation (IR). This phenotype highlights ATM as a potential target for novel inhibitors that could be used to enhance tumor cell sensitivity to radiotherapy. A targeted compound library was screened for potential inhibitors of the ATM kinase, and CP466722 was identified. The compound is nontoxic and does not inhibit phosphatidylinositol 3-kinase (PI3K) or PI3K-like protein kinase family members in cells. CP466722 inhibited cellular ATM-dependent phosphorylation events and disruption of ATM function resulted in characteristic cell cycle checkpoint defects. Inhibition of cellular ATM kinase activity was rapidly and completely reversed by removing CP466722. Interestingly, clonogenic survival assays showed that transient inhibition of ATM is sufficient to sensitize cells to IR and suggests that therapeutic radiosensitization may only require ATM inhibition for short periods of time. The ability of CP466722 to rapidly and reversibly regulate ATM activity provides a new tool to ask questions about ATM function that could not easily be addressed using genetic models or RNA interference technologies.

Authors
Rainey, MD; Charlton, ME; Stanton, RV; Kastan, MB
MLA Citation
Rainey, MD, Charlton, ME, Stanton, RV, and Kastan, MB. "Transient inhibition of ATM kinase is sufficient to enhance cellular sensitivity to ionizing radiation." Cancer Res 68.18 (September 15, 2008): 7466-7474.
PMID
18794134
Source
pubmed
Published In
Cancer Research
Volume
68
Issue
18
Publish Date
2008
Start Page
7466
End Page
7474
DOI
10.1158/0008-5472.CAN-08-0763

Human T-cell leukemia virus type 1 tax attenuates the ATM-mediated cellular DNA damage response.

Genomic instability, a hallmark of leukemic cells, is associated with malfunctioning cellular responses to DNA damage caused by defective cell cycle checkpoints and/or DNA repair. Adult T-cell leukemia, which can result from infection with human T-cell leukemia virus type 1 (HTLV-1), is associated with extensive genomic instability that has been attributed to the viral oncoprotein Tax. How Tax influences cellular responses to DNA damage to mediate genomic instability, however, remains unclear. Therefore, we investigated the effect of Tax on cellular pathways involved in recognition and repair of DNA double-strand breaks. Premature attenuation of ATM kinase activity and reduced association of MDC1 with repair foci were observed in Tax-expressing cells. Following ionizing radiation-induced S-phase checkpoint activation, Tax-expressing cells progressed more rapidly than non-Tax-expressing cells toward DNA replication. These results demonstrate that Tax expression may allow premature DNA replication in the presence of genomic lesions. Attempts to replicate in the presence of these lesions would result in gradual accumulation of mutations, leading to genome instability and cellular transformation.

Authors
Chandhasin, C; Ducu, RI; Berkovich, E; Kastan, MB; Marriott, SJ
MLA Citation
Chandhasin, C, Ducu, RI, Berkovich, E, Kastan, MB, and Marriott, SJ. "Human T-cell leukemia virus type 1 tax attenuates the ATM-mediated cellular DNA damage response." J Virol 82.14 (July 2008): 6952-6961.
PMID
18434398
Source
pubmed
Published In
Journal of virology
Volume
82
Issue
14
Publish Date
2008
Start Page
6952
End Page
6961
DOI
10.1128/JVI.02331-07

ATM and p53 are potential mediators of Chloroquine-induced resistance to mammary carcinogenesis

Authors
Loehberg, CR; Thompson, T; Kastan, MB; O'Malley, BW; Beckmann, MW
MLA Citation
Loehberg, CR, Thompson, T, Kastan, MB, O'Malley, BW, and Beckmann, MW. "ATM and p53 are potential mediators of Chloroquine-induced resistance to mammary carcinogenesis." GEBURTSHILFE UND FRAUENHEILKUNDE 68.5 (May 2008): 557-557.
Source
wos-lite
Published In
Geburtshilfe und Frauenheilkunde
Volume
68
Issue
5
Publish Date
2008
Start Page
557
End Page
557

A novel ATM-dependent pathway regulates protein phosphatase 1 in response to DNA damage.

Protein phosphatase 1 (PP1), a major protein phosphatase important for a variety of cellular responses, is activated in response to ionizing irradiation (IR)-induced DNA damage. Here, we report that IR induces the rapid dissociation of PP1 from its regulatory subunit inhibitor-2 (I-2) and that the process requires ataxia-telangiectasia mutated (ATM), a protein kinase central to DNA damage responses. In response to IR, ATM phosphorylates I-2 on serine 43, leading to the dissociation of the PP1-I-2 complex and the activation of PP1. Furthermore, ATM-mediated I-2 phosphorylation results in the inhibition of the Aurora-B kinase, the down-regulation of histone H3 serine 10 phosphorylation, and the activation of the G(2)/M checkpoint. Collectively, the results of these studies demonstrate a novel pathway that links ATM, PP1, and I-2 in the cellular response to DNA damage.

Authors
Tang, X; Hui, Z-G; Cui, X-L; Garg, R; Kastan, MB; Xu, B
MLA Citation
Tang, X, Hui, Z-G, Cui, X-L, Garg, R, Kastan, MB, and Xu, B. "A novel ATM-dependent pathway regulates protein phosphatase 1 in response to DNA damage." Mol Cell Biol 28.8 (April 2008): 2559-2566.
PMID
18250156
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
28
Issue
8
Publish Date
2008
Start Page
2559
End Page
2566
DOI
10.1128/MCB.01711-07

DNA damage responses: mechanisms and roles in human disease: 2007 G.H.A. Clowes Memorial Award Lecture.

Significant progress has been made in recent years in elucidating the molecular controls of cellular responses to DNA damage in mammalian cells. Much of our understanding of the mechanisms involved in cellular DNA damage response pathways has come from studies of human cancer susceptibility syndromes that are altered in DNA damage responses. Ataxia-telangiectasia mutated (ATM), the gene mutated in the disorder ataxia-telangiectasia, codes for a protein kinase that is a central mediator of responses to DNA double-strand breaks (DSB) in cells. Once activated, ATM phosphorylates numerous substrates in the cell that modulate the response of the cell to the DNA damage. We recently developed a novel system to create DNA DSBs at defined endogenous sites in the human genome and used this system to detect protein recruitment and loss at and around these breaks by chromatin immunoprecipitation. Results from this system showed the functional importance of ATM kinase activity and phosphorylation in the response to DSBs and supported a model in which ordered chromatin structure changes that occur after DNA breakage and that depend on functional NBS1 and ATM facilitate DNA DSB repair. Insights about these pathways provide us with opportunities to develop new approaches to benefit patients. Examples and opportunities for developing inhibitors that act as sensitizers to chemotherapy or radiation therapy or activators that could improve responses to cellular stresses, such as oxidative damage, are discussed. Relevant to the latter, we have shown benefits of an ATM activator in disease settings ranging from metabolic syndrome to cancer prevention.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "DNA damage responses: mechanisms and roles in human disease: 2007 G.H.A. Clowes Memorial Award Lecture." Mol Cancer Res 6.4 (April 2008): 517-524.
PMID
18403632
Source
pubmed
Published In
Molecular cancer research : MCR
Volume
6
Issue
4
Publish Date
2008
Start Page
517
End Page
524
DOI
10.1158/1541-7786.MCR-08-0020

Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis (vol 118, pg 79, 2008)

Authors
Maclean, KH; Dorsey, FC; Cleveland, JL; Kastan, MB
MLA Citation
Maclean, KH, Dorsey, FC, Cleveland, JL, and Kastan, MB. "Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis (vol 118, pg 79, 2008)." JOURNAL OF CLINICAL INVESTIGATION 118.4 (April 2008): 1584-1584.
Source
wos-lite
Published In
Journal of Clinical Investigation
Volume
118
Issue
4
Publish Date
2008
Start Page
1584
End Page
1584
DOI
10.1172/JC133700C1

Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis.

Despite great interest in cancer chemoprevention, effective agents are few. Here we show that chloroquine, a drug that activates the stress-responsive Atm-p53 tumor-suppressor pathway, preferentially enhances the death of Myc oncogene-overexpressing primary mouse B cells and mouse embryonic fibroblasts (MEFs) and impairs Myc-induced lymphomagenesis in a transgenic mouse model of human Burkitt lymphoma. Chloroquine-induced cell death in primary MEFs and human colorectal cancer cells was dependent upon p53, but not upon the p53 modulators Atm or Arf. Accordingly, chloroquine impaired spontaneous lymphoma development in Atm-deficient mice, a mouse model of ataxia telangiectasia, but not in p53-deficient mice. Chloroquine treatment enhanced markers of both macroautophagy and apoptosis in MEFs but ultimately impaired lysosomal protein degradation. Interestingly, chloroquine-induced cell death was not dependent on caspase-mediated apoptosis, as neither overexpression of the antiapoptotic protein Bcl-2 nor deletion of the proapoptotic Bax and Bak affected chloroquine-induced MEF death. However, when both apoptotic and autophagic pathways were blocked simultaneously, chloroquine-induced killing of Myc-overexpressing cells was blunted. Thus chloroquine induces lysosomal stress and provokes a p53-dependent cell death that does not require caspase-mediated apoptosis. These findings specifically demonstrate that intermittent chloroquine use effectively prevents cancer in mouse models of 2 genetically distinct human cancer syndromes, Burkitt lymphoma and ataxia telangiectasia, suggesting that agents targeting lysosome-mediated degradation may be effective in cancer prevention.

Authors
Maclean, KH; Dorsey, FC; Cleveland, JL; Kastan, MB
MLA Citation
Maclean, KH, Dorsey, FC, Cleveland, JL, and Kastan, MB. "Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis." J Clin Invest 118.1 (January 2008): 79-88.
PMID
18097482
Source
pubmed
Published In
Journal of Clinical Investigation
Volume
118
Issue
1
Publish Date
2008
Start Page
79
End Page
88
DOI
10.1172/JCI33700

Assessment of protein dynamics and DNA repair following generation of DNA double-strand breaks at defined genomic sites.

The formation of protein aggregates (foci) at sites of DNA double-strand breaks (DSBs) is mainly studied by immunostaining and is hence limited by the low resolution of light microscopy and the availability of appropriate and selective antibodies. Here, we describe a system using enzymatic creation of site-specific DNA DSBs within the human genome combined with chromatin immunoprecipitation (ChIP) that enables molecular probing of a DSB. Following induction of the I-PpoI enzyme and generation of DSBs, cellular DNA and proteins are crosslinked and analyzed by ChIP for specific proteins at the site of the break. The system allows the direct detection of protein and chromatin dynamics at the site of the break with high resolution, as well as direct measurement of DNA repair defects in human cells. Starting with fragmented chromatin, results can be achieved in 2-3 d.

Authors
Berkovich, E; Monnat, RJ; Kastan, MB
MLA Citation
Berkovich, E, Monnat, RJ, and Kastan, MB. "Assessment of protein dynamics and DNA repair following generation of DNA double-strand breaks at defined genomic sites." Nat Protoc 3.5 (2008): 915-922.
PMID
18451799
Source
pubmed
Published In
Nature Protocols
Volume
3
Issue
5
Publish Date
2008
Start Page
915
End Page
922
DOI
10.1038/nprot.2008.54

Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis (Journal of Clinical Investigation (2008) 118, (79-88) DOI: 10.1172/JCI33700)

Authors
Maclean, KH; Dorsey, FC; Cleveland, JL; Kastan, MB
MLA Citation
Maclean, KH, Dorsey, FC, Cleveland, JL, and Kastan, MB. "Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis (Journal of Clinical Investigation (2008) 118, (79-88) DOI: 10.1172/JCI33700)." Journal of Clinical Investigation 118.4 (2008): 1584--.
Source
scival
Published In
Journal of Clinical Investigation
Volume
118
Issue
4
Publish Date
2008
Start Page
1584-
DOI
10.1172/JCI33700C1

Ataxia telangiectasia-mutated and p53 are potential mediators of chloroquine-induced resistance to mammary carcinogenesis.

The use of agents to prevent the onset of and/or the progression to breast cancer has the potential to lower breast cancer risk. We have previously shown that the tumor-suppressor gene p53 is a potential mediator of hormone (estrogen/progesterone)-induced protection against chemical carcinogen-induced mammary carcinogenesis in animal models. Here, we show for the first time a breast cancer-protective effect of chloroquine in an animal model. Chloroquine significantly reduced the incidence of N-methyl-N-nitrosourea-induced mammary tumors in our animal model similar to estrogen/progesterone treatment. No protection was seen in our BALB/c p53-null mammary epithelium model, indicating a p53 dependency for the chloroquine effect. Using a human nontumorigenic mammary gland epithelial cell line, MCF10A, we confirm that in the absence of detectable DNA damage, chloroquine activates the tumor-suppressor p53 and the p53 downstream target gene p21, resulting in G(1) cell cycle arrest. p53 activation occurs at a posttranslational level via chloroquine-dependent phosphorylation of the checkpoint protein kinase, ataxia telangiectasia-mutated (ATM), leading to ATM-dependent phosphorylation of p53. In primary mammary gland epithelial cells isolated from p53-null mice, chloroquine does not induce G(1) cell cycle arrest compared with cells isolated from wild-type mice, also indicating a p53 dependency. Our results indicate that a short prior exposure to chloroquine may have a preventative application for mammary carcinogenesis.

Authors
Loehberg, CR; Thompson, T; Kastan, MB; Maclean, KH; Edwards, DG; Kittrell, FS; Medina, D; Conneely, OM; O'Malley, BW
MLA Citation
Loehberg, CR, Thompson, T, Kastan, MB, Maclean, KH, Edwards, DG, Kittrell, FS, Medina, D, Conneely, OM, and O'Malley, BW. "Ataxia telangiectasia-mutated and p53 are potential mediators of chloroquine-induced resistance to mammary carcinogenesis." Cancer Res 67.24 (December 15, 2007): 12026-12033.
PMID
18089834
Source
pubmed
Published In
Cancer Research
Volume
67
Issue
24
Publish Date
2007
Start Page
12026
End Page
12033
DOI
10.1158/0008-5472.CAN-07-3058

Our cells get stressed too! Implications for human disease.

Significant progress has been made in recent years elucidating the molecular controls of cellular responses to DNA damage in mammalian cells. Many of the insights that we have gained into the mechanisms involved in cellular DNA damage response pathways have come from studies of human cancer susceptibility syndromes that are altered in DNA damage responses. ATM, the gene mutated in the cancer-prone disorder, ataxia telangiectasia, is a protein kinase that is a central mediator of responses to DNA double strand breaks in cells. Such insights provide us with opportunities to develop new approaches to benefit patients. For example, inhibitors of the ATM pathway have the potential to act as sensitizers to chemotherapy or radiation therapy and could even have anti-neoplastic effects on their own. Conversely, activators of ATM could improve responses to cellular stresses such as oxidative damage. The potential benefits of ATM modulation in disease settings ranging from metabolic syndrome to cancer will be discussed.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Our cells get stressed too! Implications for human disease." Blood Cells Mol Dis 39.2 (September 2007): 148-150.
PMID
17537652
Source
pubmed
Published In
Blood Cells, Molecules and Diseases
Volume
39
Issue
2
Publish Date
2007
Start Page
148
End Page
150
DOI
10.1016/j.bcmd.2007.04.002

Atm deficiency affects both apoptosis and proliferation to augment Myc-induced lymphomagenesis.

Myc oncoproteins are commonly activated in malignancies and are sufficient to provoke many types of cancer. However, the critical mechanisms by which Myc contributes to malignant transformation are not clear. DNA damage seems to be an important initiating event in tumorigenesis. Here, we show that although Myc does not directly induce double-stranded DNA breaks, it does augment activation of the Atm/p53 DNA damage response pathway, suggesting that Atm may function as a guardian against Myc-induced transformation. Indeed, we show that Atm loss augments Myc-induced lymphomagenesis and impairs Myc-induced apoptosis, which normally harnesses Myc-driven tumorigenesis. Surprisingly, Atm loss also augments the proliferative response induced by Myc, and this augmentation is associated with enhanced suppression of the expression of the cyclin-dependent kinase inhibitor p27(Kip1). Therefore, regulation of cell proliferation and p27(Kip1) seems to be a contributing mechanism by which Atm holds tumor formation in check.

Authors
Maclean, KH; Kastan, MB; Cleveland, JL
MLA Citation
Maclean, KH, Kastan, MB, and Cleveland, JL. "Atm deficiency affects both apoptosis and proliferation to augment Myc-induced lymphomagenesis." Mol Cancer Res 5.7 (July 2007): 705-711.
PMID
17634425
Source
pubmed
Published In
Molecular cancer research : MCR
Volume
5
Issue
7
Publish Date
2007
Start Page
705
End Page
711
DOI
10.1158/1541-7786.MCR-07-0058

Roles of ATM and NBS1 in chromatin structure modulation and DNA double-strand break repair.

We developed a novel system to create DNA double-strand breaks (DSBs) at defined endogenous sites in the human genome, and used this system to detect protein recruitment and loss at and around these breaks by chromatin immunoprecipitation (ChIP). The detection of human ATM protein at site-specific DSBs required functional NBS1 protein, ATM kinase activity and ATM autophosphorylation on Ser 1981. DSB formation led to the localized disruption of nucleosomes, a process that depended on both functional NBS1 and ATM. These two proteins were also required for efficient recruitment of the repair cofactor XRCC4 to DSBs, and for efficient DSB repair. These results demonstrate the functional importance of ATM kinase activity and phosphorylation in the response to DSBs, and support a model in which ordered chromatin structure changes that occur after DNA breakage depend on functional NBS1 and ATM, and facilitate DNA DSB repair.

Authors
Berkovich, E; Monnat, RJ; Kastan, MB
MLA Citation
Berkovich, E, Monnat, RJ, and Kastan, MB. "Roles of ATM and NBS1 in chromatin structure modulation and DNA double-strand break repair." Nat Cell Biol 9.6 (June 2007): 683-690.
PMID
17486112
Source
pubmed
Published In
Nature Cell Biology
Volume
9
Issue
6
Publish Date
2007
Start Page
683
End Page
690
DOI
10.1038/ncb1599

p53: a two-faced cancer gene.

Authors
Kastan, MB; Berkovich, E
MLA Citation
Kastan, MB, and Berkovich, E. "p53: a two-faced cancer gene." Nat Cell Biol 9.5 (May 2007): 489-491.
PMID
17473858
Source
pubmed
Published In
Nature Cell Biology
Volume
9
Issue
5
Publish Date
2007
Start Page
489
End Page
491
DOI
10.1038/ncb0507-489

Wild-type p53: tumors can't stand it.

Most malignant tumors disrupt the p53 signaling pathway in order to grow and survive. Although many genes in addition to p53 are mutated in tumors, recent studies by Ventura et al. (2007) and Xue et al. (2007) suggest that restoring p53 function alone is sufficient to cause regression of several different tumor types in mice and thus might represent a potent therapeutic strategy to treat certain human cancers. Martins et al. (2006) also demonstrate that restoration of p53 activity results in tumor regression but add the sobering caveat that tumors may be able to quickly generate resistance by finding other ways to disrupt the p53 pathway.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Wild-type p53: tumors can't stand it." Cell 128.5 (March 9, 2007): 837-840. (Review)
PMID
17350571
Source
pubmed
Published In
Cell
Volume
128
Issue
5
Publish Date
2007
Start Page
837
End Page
840
DOI
10.1016/j.cell.2007.02.022

A message from the editor

Authors
Kastan, MB
MLA Citation
Kastan, MB. "A message from the editor." Molecular Cancer Research 5.11 (2007): xii-.
Source
scival
Published In
Molecular cancer research : MCR
Volume
5
Issue
11
Publish Date
2007
Start Page
xii

Editor's note

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Editor's note." Molecular Cancer Research 5.1 (2007): viii-.
Source
scival
Published In
Molecular cancer research : MCR
Volume
5
Issue
1
Publish Date
2007
Start Page
viii

ATM-dependent suppression of stress signaling reduces vascular disease in metabolic syndrome.

Metabolic syndrome is associated with insulin resistance and atherosclerosis. Here, we show that deficiency of one or two alleles of ATM, the protein mutated in the cancer-prone disease ataxia telangiectasia, worsens features of the metabolic syndrome, increases insulin resistance, and accelerates atherosclerosis in apoE-/- mice. Transplantation with ATM-/- as compared to ATM+/+ bone marrow increased vascular disease. Jun N-terminal kinase (JNK) activity was increased in ATM-deficient cells. Treatment of ATM+/+apoE-/- mice with low-dose chloroquine, an ATM activator, decreased atherosclerosis. In an ATM-dependent manner, chloroquine decreased macrophage JNK activity, decreased macrophage lipoprotein lipase activity (a proatherogenic consequence of JNK activation), decreased blood pressure, and improved glucose tolerance. Chloroquine also improved metabolic abnormalities in ob/ob and db/db mice. These results suggest that ATM-dependent stress pathways mediate susceptibility to the metabolic syndrome and that chloroquine or related agents promoting ATM activity could modulate insulin resistance and decrease vascular disease.

Authors
Schneider, JG; Finck, BN; Ren, J; Standley, KN; Takagi, M; Maclean, KH; Bernal-Mizrachi, C; Muslin, AJ; Kastan, MB; Semenkovich, CF
MLA Citation
Schneider, JG, Finck, BN, Ren, J, Standley, KN, Takagi, M, Maclean, KH, Bernal-Mizrachi, C, Muslin, AJ, Kastan, MB, and Semenkovich, CF. "ATM-dependent suppression of stress signaling reduces vascular disease in metabolic syndrome." Cell Metab 4.5 (November 2006): 377-389.
PMID
17084711
Source
pubmed
Published In
Cell Metabolism
Volume
4
Issue
5
Publish Date
2006
Start Page
377
End Page
389
DOI
10.1016/j.cmet.2006.10.002

A subtle t(3;8) results in plausible juxtaposition of MYC and BCL6 in a child with Burkitt lymphoma/leukemia and ataxia-telangiectasia.

Translocations involving 3q27 that affect the BCL6 gene are common and specific chromosomal abnormalities in B-cell precursor non-Hodgkin lymphoma (mainly diffuse large-cell and follicular lymphoma), but they have not been reported in Burkitt lymphoma. Here, we describe a case in which a BCL6 rearrangement and additional complex cytogenetic abnormalities occurred in a child with Burkitt lymphoma/leukemia and ataxia-telangiectasia. Although cytogenetic analysis of the bone marrow revealed clonal abnormalities of chromosome arms 8q and 14p and other subclonal abnormalities, the t(8;14) or its variants typically associated with Burkitt lymphoma were not observed. Fluorescence in situ hybridization with locus-specific probes and multicolor spectral karyotyping demonstrated a complex pattern of chromosomal rearrangements leading to a subtle t(3;8)(q27;q24.1) that rearranged BCL6 and placed it adjacent to MYC. We speculate that this genetic lesion occurred as a result of chromosomal instability due to the underlying disease.

Authors
Sandlund, JT; Kastan, MB; Kennedy, W; Behm, F; Entrekin, E; Pui, C-H; Kalwinsky, DT; Raimondi, SC
MLA Citation
Sandlund, JT, Kastan, MB, Kennedy, W, Behm, F, Entrekin, E, Pui, C-H, Kalwinsky, DT, and Raimondi, SC. "A subtle t(3;8) results in plausible juxtaposition of MYC and BCL6 in a child with Burkitt lymphoma/leukemia and ataxia-telangiectasia." Cancer Genet Cytogenet 168.1 (July 1, 2006): 69-72.
PMID
16772123
Source
pubmed
Published In
Cancer Genetics and Cytogenetics
Volume
168
Issue
1
Publish Date
2006
Start Page
69
End Page
72
DOI
10.1016/j.cancergencyto.2005.12.013

Spatial organization of the mammalian genome surveillance machinery in response to DNA strand breaks.

We show that DNA double-strand breaks (DSBs) induce complex subcompartmentalization of genome surveillance regulators. Chromatin marked by gamma-H2AX is occupied by ataxia telangiectasia-mutated (ATM) kinase, Mdc1, and 53BP1. In contrast, repair factors (Rad51, Rad52, BRCA2, and FANCD2), ATM and Rad-3-related (ATR) cascade (ATR, ATR interacting protein, and replication protein A), and the DNA clamp (Rad17 and -9) accumulate in subchromatin microcompartments delineated by single-stranded DNA (ssDNA). BRCA1 and the Mre11-Rad50-Nbs1 complex interact with both of these compartments. Importantly, some core DSB regulators do not form cytologically discernible foci. These are further subclassified to proteins that connect DSBs with the rest of the nucleus (Chk1 and -2), that assemble at unprocessed DSBs (DNA-PK/Ku70), and that exist on chromatin as preassembled complexes but become locally modified after DNA damage (Smc1/Smc3). Finally, checkpoint effectors such as p53 and Cdc25A do not accumulate at DSBs at all. We propose that subclassification of DSB regulators according to their residence sites provides a useful framework for understanding their involvement in diverse processes of genome surveillance.

Authors
Bekker-Jensen, S; Lukas, C; Kitagawa, R; Melander, F; Kastan, MB; Bartek, J; Lukas, J
MLA Citation
Bekker-Jensen, S, Lukas, C, Kitagawa, R, Melander, F, Kastan, MB, Bartek, J, and Lukas, J. "Spatial organization of the mammalian genome surveillance machinery in response to DNA strand breaks." J Cell Biol 173.2 (April 24, 2006): 195-206.
PMID
16618811
Source
pubmed
Published In
The Journal of Cell Biology
Volume
173
Issue
2
Publish Date
2006
Start Page
195
End Page
206
DOI
10.1083/jcb.200510130

The Rad50S allele promotes ATM-dependent DNA damage responses and suppresses ATM deficiency: implications for the Mre11 complex as a DNA damage sensor.

Genetic and cytologic data from Saccharomyces cerevisiae and mammals implicate the Mre11 complex, consisting of Mre11, Rad50, and Nbs1, as a sensor of DNA damage, and indicate that the complex influences the activity of ataxia-telangiectasia mutated (ATM) in the DNA damage response. Rad50(S/S) mice exhibit precipitous apoptotic attrition of hematopoietic cells. We generated ATM- and Chk2-deficient Rad50(S/S) mice and found that Rad50(S/S) cellular attrition was strongly ATM and Chk2 dependent. The hypomorphic Mre11(ATLD1) and Nbs1(Delta)(B) alleles conferred similar rescue of Rad50(S/S)-dependent hematopoietic failure. These data indicate that the Mre11 complex activates an ATM-Chk2-dependent apoptotic pathway. We find that apoptosis and cell cycle checkpoint activation are parallel outcomes of the Mre11 complex-ATM pathway. Conversely, the Rad50(S) mutation mitigated several phenotypic features of ATM deficiency. We propose that the Rad50(S) allele is hypermorphic for DNA damage signaling, and that the resulting constitutive low-level activation of the DNA damage response accounts for the partial suppression of ATM deficiency in Rad50(S/S) Atm(-/-) mice.

Authors
Morales, M; Theunissen, J-WF; Kim, CFB; Kitagawa, R; Kastan, MB; Petrini, JHJ
MLA Citation
Morales, M, Theunissen, J-WF, Kim, CFB, Kitagawa, R, Kastan, MB, and Petrini, JHJ. "The Rad50S allele promotes ATM-dependent DNA damage responses and suppresses ATM deficiency: implications for the Mre11 complex as a DNA damage sensor." Genes Dev 19.24 (December 15, 2005): 3043-3054.
PMID
16357220
Source
pubmed
Published In
Genes & development
Volume
19
Issue
24
Publish Date
2005
Start Page
3043
End Page
3054
DOI
10.1101/gad.1373705

Cell biology: A BID for the pathway.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Cell biology: A BID for the pathway." Nature 437.7062 (October 20, 2005): 1103-.
PMID
16237431
Source
pubmed
Published In
Nature
Volume
437
Issue
7062
Publish Date
2005
Start Page
1103
DOI
10.1038/4371103a

Regulation of p53 translation and induction after DNA damage by ribosomal protein L26 and nucleolin.

Increases in p53 protein levels after DNA damage have largely been attributed to an increase in the half-life of p53 protein. Here we demonstrate that increased translation of p53 mRNA is also a critical step in the induction of p53 protein in irradiated cells. Ribosomal protein L26 (RPL26) and nucleolin were found to bind to the 5' untranslated region (UTR) of p53 mRNA and to control p53 translation and induction after DNA damage. RPL26 preferentially binds to the 5'UTR after DNA damage, and its overexpression enhances association of p53 mRNA with heavier polysomes, increases the rate of p53 translation, induces G1 cell-cycle arrest, and augments irradiation-induced apoptosis. Opposite effects were seen when RPL26 expression was inhibited. In contrast, nucleolin overexpression suppresses p53 translation and induction after DNA damage, whereas nucleolin downregulation promotes p53 expression. These findings demonstrate the importance of increased translation of p53 in DNA-damage responses and suggest critical roles for RPL26 and nucleolin in affecting p53 induction.

Authors
Takagi, M; Absalon, MJ; McLure, KG; Kastan, MB
MLA Citation
Takagi, M, Absalon, MJ, McLure, KG, and Kastan, MB. "Regulation of p53 translation and induction after DNA damage by ribosomal protein L26 and nucleolin." Cell 123.1 (October 7, 2005): 49-63.
PMID
16213212
Source
pubmed
Published In
Cell
Volume
123
Issue
1
Publish Date
2005
Start Page
49
End Page
63
DOI
10.1016/j.cell.2005.07.034

ATM activation in normal human tissues and testicular cancer.

The ATM kinase is a tumor suppressor and key regulator of biological responses to DNA damage. Cultured cells respond to genotoxic insults that induce DNA double-strand breaks by prompt activation of ATM through its autophosphorylation on serine 1981. However, whether ATM-S1981 becomes phosphorylated in vivo, for example during physiological processes that generate DSBs, is unknown. Here we produced phospho-specific monoclonal antibodies against S1981-phosphorylated ATM (pS-ATM), and applied them to immunohistochemical analyses of a wide range of normal human tissues and testicular tumors. Our data show that regardless of proliferation and differentiation, most human tissues contain only the S1981-nonphosphorylated, inactive form of ATM. In contrast, nuclear staining for pS-ATM was detected in subsets of bone-marrow lymphocytes and primary spermatocytes in the adult testes, cell types in which DSBs are generated during physiological V(D)J recombination and meiotic recombination, respectively. Among testicular germ-cell tumors, an aberrant constitutive pS-ATM was observed especially in embryonal carcinomas, less in seminomas, and only modestly in teratomas and the pre-invasive carcinoma-in-situ stage. Compared with pS-ATM, phosphorylated histone H2AX (gammaH2AX), another DNA damage marker and ATM substrate, was detected in a higher proportion of cancer cells, and also in normal fetal gonocytes, and a wider range of adult spermatocyte differentiation stages. Collectively, our results strongly support the physiological relevance of the recently proposed model of ATM autoactivation, and provide further evidence for constitutive activation of the DNA damage machinery during cancer development. The new tools characterized here should facilitate monitoring of ATM activation in clinical specimens, and help develop future treatment strategies.

Authors
Bartkova, J; Bakkenist, CJ; Rajpert-De Meyts, E; Skakkebaek, NE; Sehested, M; Lukas, J; Kastan, MB; Bartek, J
MLA Citation
Bartkova, J, Bakkenist, CJ, Rajpert-De Meyts, E, Skakkebaek, NE, Sehested, M, Lukas, J, Kastan, MB, and Bartek, J. "ATM activation in normal human tissues and testicular cancer." Cell Cycle 4.6 (June 2005): 838-845.
PMID
15846060
Source
pubmed
Published In
Cell Cycle
Volume
4
Issue
6
Publish Date
2005
Start Page
838
End Page
845
DOI
10.4161/cc.4.6.1742

20 years of DNA damage signaling to p53

© 2007 Springer. All Rights Reserved.The short history of p53 contains an overwhelming number of facts and hypotheses, presenting the challenge of integrating diverse and sometimes mutually exclusive ideas into a coherent picture. It is important to make a distinction between p53 tumor suppressor activity, the mechanism of which remains speculative, and p53 responses to DNA damage, which are well characterized. Because critical steps in tumorigenesis involve genomic fixation of DNA damage-induced mutations, it seems reasonable to assume that DNA damage signaling to p53 would activate p53 tumor suppressor activity. However, this has not been demonstrated, and p53 tumor suppressor activity may not require the acute p53 response to DNA damage (Komarov et al., 1999). Nonetheless, the genotoxic chemicals and ionizing radiation that are clinically used to treat human cancer indisputably activate wild type p53.

Authors
McLure, KG; Kastan, MB
MLA Citation
McLure, KG, and Kastan, MB. "20 years of DNA damage signaling to p53." 25 Years of p53 Research. January 1, 2005. 53-71.
Source
scopus
Publish Date
2005
Start Page
53
End Page
71
DOI
10.1007/978-1-4020-2922-6_3

Erratum: Regulation of p53 translation and induction after DNA damage by ribosomal protein L26 and nucleolin (Cell (October 7, 2005) 123 (49-63))

Authors
Takagi, M; Absalon, MJ; McLure, KG; Kastan, MB
MLA Citation
Takagi, M, Absalon, MJ, McLure, KG, and Kastan, MB. "Erratum: Regulation of p53 translation and induction after DNA damage by ribosomal protein L26 and nucleolin (Cell (October 7, 2005) 123 (49-63))." Cell 123.3 (2005): 536-537.
Source
scival
Published In
Cell
Volume
123
Issue
3
Publish Date
2005
Start Page
536
End Page
537
DOI
10.1016/j.cell.2005.10.012

DNA damage responses: Cancer and beyond

Authors
Kastan, MB
MLA Citation
Kastan, MB. "DNA damage responses: Cancer and beyond." Scientist 19.19 (2005): 24-25.
Source
scival
Published In
Scientist (Philadelphia, Pa.)
Volume
19
Issue
19
Publish Date
2005
Start Page
24
End Page
25

The ATM-dependent DNA damage signaling pathway.

Many of the insights that we have gained into the mechanisms involved in cellular DNA damage response pathways have come from studies of human cancer susceptibility syndromes that are altered in DNA damage responses. ATM, the gene mutated in the disorder, ataxia-telangiectasia, is a protein kinase that is a central mediator of responses to DNA double-strand breaks in cells. Recent studies have elucidated the mechanism by which DNA damage activates the ATM kinase and initiates these critical cellular signaling pathways. The SMC1 protein appears to be a particularly important target of the ATM kinase, playing critical roles in controlling DNA replication forks and DNA repair after the damage. A major role for the NBS1 and BRCA1 proteins appears to be in the recruitment of an activated ATM kinase molecule to the sites of DNA breaks so that ATM can phosphorylate SMC1. Generation of mice and cells that are unable to phosphorylate SMC1 demonstrated the importance of SMC1 phosphorylation in the DNA-damage-induced S-phase checkpoint, in determining rates of repair of chromosomal breaks, and in determining cell survival after DNA damage. Focusing on ATM and SMC1, the molecular controls of these pathways is discussed.

Authors
Kitagawa, R; Kastan, MB
MLA Citation
Kitagawa, R, and Kastan, MB. "The ATM-dependent DNA damage signaling pathway." Cold Spring Harb Symp Quant Biol 70 (2005): 99-109. (Review)
PMID
16869743
Source
pubmed
Published In
Cold Spring Harbor Laboratory: Symposia on Quantitative Biology
Volume
70
Publish Date
2005
Start Page
99
End Page
109
DOI
10.1101/sqb.2005.70.002

Activation of ATM and p53 in mammary gland epithelial cells as a possible breast cancer prevention model.

Authors
Loehberg, CR; Thompson, T; Kastan, MB; Conneely, OM; Medina, D; O'Malley, BW
MLA Citation
Loehberg, CR, Thompson, T, Kastan, MB, Conneely, OM, Medina, D, and O'Malley, BW. "Activation of ATM and p53 in mammary gland epithelial cells as a possible breast cancer prevention model." 2005.
Source
wos-lite
Published In
Breast Cancer Research and Treatment
Volume
94
Publish Date
2005
Start Page
S173
End Page
S173

DNA damage response pathways in cancer causation and treatment

Authors
Kastan, MB; Kitagawa, R; Bakkenist, CJ
MLA Citation
Kastan, MB, Kitagawa, R, and Bakkenist, CJ. "DNA damage response pathways in cancer causation and treatment." 2005.
Source
wos-lite
Published In
Breast Cancer Research
Volume
7
Publish Date
2005
Start Page
S2
End Page
S3
DOI
10.1186/bcr1049

Cell-cycle checkpoints and cancer.

All life on earth must cope with constant exposure to DNA-damaging agents such as the Sun's radiation. Highly conserved DNA-repair and cell-cycle checkpoint pathways allow cells to deal with both endogenous and exogenous sources of DNA damage. How much an individual is exposed to these agents and how their cells respond to DNA damage are critical determinants of whether that individual will develop cancer. These cellular responses are also important for determining toxicities and responses to current cancer therapies, most of which target the DNA.

Authors
Kastan, MB; Bartek, J
MLA Citation
Kastan, MB, and Bartek, J. "Cell-cycle checkpoints and cancer." Nature 432.7015 (November 18, 2004): 316-323. (Review)
PMID
15549093
Source
pubmed
Published In
Nature
Volume
432
Issue
7015
Publish Date
2004
Start Page
316
End Page
323
DOI
10.1038/nature03097

NAD+ modulates p53 DNA binding specificity and function.

DNA damage induces p53 DNA binding activity, which affects tumorigenesis, tumor responses to therapies, and the toxicities of cancer therapies (B. Vogelstein, D. Lane, and A. J. Levine, Nature 408:307-310, 2000; K. H. Vousden and X. Lu, Nat. Rev. Cancer 2:594-604, 2002). Both transcriptional and transcription-independent activities of p53 contribute to DNA damage-induced cell cycle arrest, apoptosis, and aneuploidy prevention (M. B. Kastan et al., Cell 71:587-597, 1992; K. H. Vousden and X. Lu, Nat. Rev. Cancer 2:594-604, 2002). Small-molecule manipulation of p53 DNA binding activity has been an elusive goal, but here we show that NAD(+) binds to p53 tetramers, induces a conformational change, and modulates p53 DNA binding specificity in vitro. Niacinamide (vitamin B(3)) increases the rate of intracellular NAD(+) synthesis, alters radiation-induced p53 DNA binding specificity, and modulates activation of a subset of p53 transcriptional targets. These effects are likely due to a direct effect of NAD(+) on p53, as a molecule structurally related to part of NAD(+), TDP, also inhibits p53 DNA binding, and the TDP precursor, thiamine (vitamin B(1)), inhibits intracellular p53 activity. Niacinamide and thiamine affect two p53-regulated cellular responses to ionizing radiation: rereplication and apoptosis. Thus, niacinamide and thiamine form a novel basis for the development of small molecules that affect p53 function in vivo, and these results suggest that changes in cellular energy metabolism may regulate p53.

Authors
McLure, KG; Takagi, M; Kastan, MB
MLA Citation
McLure, KG, Takagi, M, and Kastan, MB. "NAD+ modulates p53 DNA binding specificity and function." Mol Cell Biol 24.22 (November 2004): 9958-9967.
PMID
15509798
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
24
Issue
22
Publish Date
2004
Start Page
9958
End Page
9967
DOI
10.1128/MCB.24.22.9958-9967.2004

BRCA1 is required for common-fragile-site stability via its G2/M checkpoint function.

Common fragile sites are loci that form chromosome gaps or breaks when DNA synthesis is partially inhibited. Fragile sites are prone to deletions, translocations, and other rearrangements that can cause the inactivation of associated tumor suppressor genes in cancer cells. It was previously shown that ATR is critical to fragile-site stability and that ATR-deficient cells have greatly elevated fragile-site expression (A. M. Casper, P. Nghiem, M. F. Arlt, and T. W. Glover, Cell 111:779-789, 2002). Here we demonstrate that mouse and human cells deficient for BRCA1, due to mutation or knockdown by RNA interference, also have elevated fragile-site expression. We further show that BRCA1 functions in the induction of the G(2)/M checkpoint after aphidicolin-induced replication stalling and that this checkpoint function is involved in fragile-site stability. These data indicate that BRCA1 is important in fragile-site stability and that fragile sites are recognized by the G(2)/M checkpoint pathway, in which BRCA1 plays a key role. Furthermore, they suggest that mutations in BRCA1 or interacting proteins could lead to rearrangements at fragile sites in cancer cells.

Authors
Arlt, MF; Xu, B; Durkin, SG; Casper, AM; Kastan, MB; Glover, TW
MLA Citation
Arlt, MF, Xu, B, Durkin, SG, Casper, AM, Kastan, MB, and Glover, TW. "BRCA1 is required for common-fragile-site stability via its G2/M checkpoint function." Mol Cell Biol 24.15 (August 2004): 6701-6709.
PMID
15254237
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
24
Issue
15
Publish Date
2004
Start Page
6701
End Page
6709
DOI
10.1128/MCB.24.15.6701-6709.2004

The telomeric protein TRF2 binds the ATM kinase and can inhibit the ATM-dependent DNA damage response.

The telomeric protein TRF2 is required to prevent mammalian telomeres from activating DNA damage checkpoints. Here we show that overexpression of TRF2 affects the response of the ATM kinase to DNA damage. Overexpression of TRF2 abrogated the cell cycle arrest after ionizing radiation and diminished several other readouts of the DNA damage response, including phosphorylation of Nbs1, induction of p53, and upregulation of p53 targets. TRF2 inhibited autophosphorylation of ATM on S1981, an early step in the activation of this kinase. A region of ATM containing S1981 was found to directly interact with TRF2 in vitro, and ATM immunoprecipitates contained TRF2. We propose that TRF2 has the ability to inhibit ATM activation at telomeres. Because TRF2 is abundant at chromosome ends but not elsewhere in the nucleus, this mechanism of checkpoint control could specifically block a DNA damage response at telomeres without affecting the surveillance of chromosome internal damage.

Authors
Karlseder, J; Hoke, K; Mirzoeva, OK; Bakkenist, C; Kastan, MB; Petrini, JHJ; de Lange, T
MLA Citation
Karlseder, J, Hoke, K, Mirzoeva, OK, Bakkenist, C, Kastan, MB, Petrini, JHJ, and de Lange, T. "The telomeric protein TRF2 binds the ATM kinase and can inhibit the ATM-dependent DNA damage response." PLoS Biol 2.8 (August 2004): E240-.
PMID
15314656
Source
pubmed
Published In
PLoS biology
Volume
2
Issue
8
Publish Date
2004
Start Page
E240
DOI
10.1371/journal.pbio.0020240

Initiating cellular stress responses.

The phosphoinositide 3-kinase related kinases (PIKKs) mediate responses to diverse stresses, including DNA double-strand breaks (DSBs), abnormal replication fork progression, the recognition of premature termination codons in mRNAs, and inadequate nutrient availability. Rigorous control of these kinases limits cellular damage and promotes cell viability in the presence of stress. Control mechanisms include the localization of PIKKs into multiprotein complexes at the sites of damage and mediation of protein-protein contacts such that substrates are allowed access to the PIKK catalytic domains.

Authors
Bakkenist, CJ; Kastan, MB
MLA Citation
Bakkenist, CJ, and Kastan, MB. "Initiating cellular stress responses." Cell 118.1 (July 9, 2004): 9-17. (Review)
PMID
15242640
Source
pubmed
Published In
Cell
Volume
118
Issue
1
Publish Date
2004
Start Page
9
End Page
17
DOI
10.1016/j.cell.2004.06.023

Phosphatases join kinases in DNA-damage response pathways.

An inappropriate imbalance of kinase and phosphatase activities could be deleterious to cellular processes such as proliferation. Cellular responses to DNA damage use signal-transduction pathways involving phosphorylation events, and such modifications must be reversible to make these responses transient, rather than permanent, events. Three recent articles describe roles for two phosphatases in signaling pathways that are activated after DNA damage.

Authors
Bakkenist, CJ; Kastan, MB
MLA Citation
Bakkenist, CJ, and Kastan, MB. "Phosphatases join kinases in DNA-damage response pathways." Trends Cell Biol 14.7 (July 2004): 339-341. (Review)
PMID
15246426
Source
pubmed
Published In
Trends in Cell Biology
Volume
14
Issue
7
Publish Date
2004
Start Page
339
End Page
341
DOI
10.1016/j.tcb.2004.05.001

Phosphorylation of SMC1 is a critical downstream event in the ATM-NBS1-BRCA1 pathway.

The ATM protein kinase is activated by intermolecular autophosphorylation in response to DNA damage and initiates cellular signaling pathways that facilitate cell survival and reduce chromosomal breakage. Here, we show that NBS1 and BRCA1 are required for the recruitment of previously activated ATM to the sites of DNA breaks after ionizing irradiation, and that this recruitment is required for the phosphorylation of SMC1 by ATM. To explore the functional importance of SMC1 phosphorylation, murine cells were generated, in which the two damage-induced phosphorylation sites in SMC1 are mutated. Although these cells demonstrate normal phosphorylation and focus formation of ATM, NBS1, and BRCA1 proteins after IR, they exhibit a defective S-phase checkpoint, decreased survival, and increased chromosomal aberrations after DNA damage. These observations suggest that many of the abnormal stress responses seen in cells lacking ATM, NBS1, or BRCA1 result from a failure of ATM migration to sites of DNA breaks and a resultant lack of SMC1 phosphorylation.

Authors
Kitagawa, R; Bakkenist, CJ; McKinnon, PJ; Kastan, MB
MLA Citation
Kitagawa, R, Bakkenist, CJ, McKinnon, PJ, and Kastan, MB. "Phosphorylation of SMC1 is a critical downstream event in the ATM-NBS1-BRCA1 pathway." Genes Dev 18.12 (June 15, 2004): 1423-1438.
PMID
15175241
Source
pubmed
Published In
Genes & development
Volume
18
Issue
12
Publish Date
2004
Start Page
1423
End Page
1438
DOI
10.1101/gad.1200304

Molecular cross-talk among chromosome fragility syndromes.

Authors
Surrallés, J; Jackson, SP; Jasin, M; Kastan, MB; West, SC; Joenje, H
MLA Citation
Surrallés, J, Jackson, SP, Jasin, M, Kastan, MB, West, SC, and Joenje, H. "Molecular cross-talk among chromosome fragility syndromes." Genes Dev 18.12 (June 15, 2004): 1359-1370.
PMID
15198978
Source
pubmed
Published In
Genes & development
Volume
18
Issue
12
Publish Date
2004
Start Page
1359
End Page
1370
DOI
10.1101/gad.1216304

Disappearance of the telomere dysfunction-induced stress response in fully senescent cells.

Replicative senescence is a natural barrier to cellular proliferation that is triggered by telomere erosion and dysfunction. Here, we demonstrate that ATM activation and H2AX-gamma nuclear focus formation are sensitive markers of telomere dysfunction in primary human fibroblasts. Whereas the activated form of ATM and H2AX-gamma foci were rarely observed in early-passage cells, they were readily detected in late-passage cells. The ectopic expression of telomerase in late-passage cells abrogated ATM activation and H2AX-gamma focus formation, suggesting that these stress responses were the consequence of telomere dysfunction. ATM activation was induced in quiescent fibroblasts by inhibition of TRF2 binding to telomeres, indicating that telomere uncapping is sufficient to initiate the telomere signaling response; breakage of chromosomes with telomeric associations is not required for this activation. Although ATM activation and H2AX-gamma foci were readily observed in late-passage cells, they disappeared once cells became fully senescent, indicating that constitutive signaling from dysfunctional telomeres is not required for the maintenance of senescence.

Authors
Bakkenist, CJ; Drissi, R; Wu, J; Kastan, MB; Dome, JS
MLA Citation
Bakkenist, CJ, Drissi, R, Wu, J, Kastan, MB, and Dome, JS. "Disappearance of the telomere dysfunction-induced stress response in fully senescent cells." Cancer Res 64.11 (June 1, 2004): 3748-3752.
PMID
15172978
Source
pubmed
Published In
Cancer Research
Volume
64
Issue
11
Publish Date
2004
Start Page
3748
End Page
3752
DOI
10.1158/0008-5472.CAN-04-0453

Chromatin association of rad17 is required for an ataxia telangiectasia and rad-related kinase-mediated S-phase checkpoint in response to low-dose ultraviolet radiation.

Activation of the S-phase checkpoint results in an inhibition of DNA synthesis in response to DNA damage. This is an active cellular response that may enhance cell survival and limit heritable genetic abnormalities. While much attention has been paid to elucidating signal transduction pathways regulating the ionizing radiation-induced S-phase checkpoint, less is known about whether UV radiation initiates the process and the mechanism controlling it. Here, we demonstrate that low-dose UV radiation activates an S-phase checkpoint that requires the ataxia telangiectasia and Rad-related kinase (ATR). ATR regulates the S-phase checkpoint through phosphorylation of the downstream target structural maintenance of chromosomal protein 1. Furthermore, the ATPase activity of Rad17 is crucial for its chromatin association and for the functional effects of ATR activation in response to low-dose UV radiation. These results suggest that low-dose UV radiation activates an S-phase checkpoint requiring ATR-mediated signal transduction pathway.

Authors
Garg, R; Callens, S; Lim, D-S; Canman, CE; Kastan, MB; Xu, B
MLA Citation
Garg, R, Callens, S, Lim, D-S, Canman, CE, Kastan, MB, and Xu, B. "Chromatin association of rad17 is required for an ataxia telangiectasia and rad-related kinase-mediated S-phase checkpoint in response to low-dose ultraviolet radiation." Mol Cancer Res 2.6 (June 2004): 362-369.
PMID
15235112
Source
pubmed
Published In
Molecular cancer research : MCR
Volume
2
Issue
6
Publish Date
2004
Start Page
362
End Page
369

ATM haploinsufficiency produces vascular insulin resistance, impaired glucose tolerance, hypertension, and accelerated atherosclerosis in apoE null mice

Authors
Schneider, JG; Ren, J; Feng, C; Coleman, T; Kastan, MB; Muslin, AJ; Semenkovich, CF
MLA Citation
Schneider, JG, Ren, J, Feng, C, Coleman, T, Kastan, MB, Muslin, AJ, and Semenkovich, CF. "ATM haploinsufficiency produces vascular insulin resistance, impaired glucose tolerance, hypertension, and accelerated atherosclerosis in apoE null mice." May 2004.
Source
wos-lite
Published In
Arteriosclerosis, Thrombosis, and Vascular Biology
Volume
24
Issue
5
Publish Date
2004
Start Page
E5
End Page
E5

Distinct functional domains of Nbs1 modulate the timing and magnitude of ATM activation after low doses of ionizing radiation.

The ATM kinase is a tumour suppressor and a key activator of genome integrity checkpoints in mammalian cells exposed to ionizing radiation (IR) and other insults that elicit DNA double-strand breaks (DSBs). In response to IR, autophosphorylation on serine 1981 causes dissociation of ATM dimers and initiates cellular ATM kinase activity. Here, we show that the kinetics and magnitude of ATM Ser1981 phosphorylation after exposure of human fibroblasts to low doses (2 Gy) of IR are altered in cells deficient in Nbs1, a substrate of ATM and a component of the MRN (Mre11-Rad50-Nbs1) complex involved in processing/repair of DSBs and ATM-dependent cell cycle checkpoints. Timely phosphorylation of both ATM Ser1981 and the ATM substrate Smc1 after IR were rescued via retrovirally mediated reconstitution of Nbs1-deficient cells by wild-type Nbs1 or mutants of Nbs1 defective in the FHA domain or nonphosphorylatable by ATM, but not by Nbs1 lacking the Mre11-interaction domain. Our data indicate that apart from its role downstream of ATM in the DNA damage checkpoint network, the MRN complex serves also as a modulator/amplifier of ATM activity. Although not absolutely required for ATM activation, the MRN nuclease complex may help reach the threshold activity of ATM necessary for optimal genome maintenance and prevention of cancer.

Authors
Horejsí, Z; Falck, J; Bakkenist, CJ; Kastan, MB; Lukas, J; Bartek, J
MLA Citation
Horejsí, Z, Falck, J, Bakkenist, CJ, Kastan, MB, Lukas, J, and Bartek, J. "Distinct functional domains of Nbs1 modulate the timing and magnitude of ATM activation after low doses of ionizing radiation." Oncogene 23.17 (April 15, 2004): 3122-3127.
PMID
15048089
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
23
Issue
17
Publish Date
2004
Start Page
3122
End Page
3127
DOI
10.1038/sj.onc.1207447

ATM - the first step in helping cells deal with DNA damage

Authors
Kastan, MB
MLA Citation
Kastan, MB. "ATM - the first step in helping cells deal with DNA damage." BIOMEDICINE & PHARMACOTHERAPY 58.1 (January 2004): 72-73.
Source
wos-lite
Published In
Biomedicine & Pharmacotherapy
Volume
58
Issue
1
Publish Date
2004
Start Page
72
End Page
73
DOI
10.1016/S0753-3322(03)00045-3

Analyzing cell cycle checkpoints after ionizing radiation.

Several methods to measure cell cycle perturbation after exposure to ionizing radiation are presented in this chapter. These methods include the G1 checkpoint assay by 5' bromode-oxyuridine (BrdUrd) labeling followed by flow cytometric analysis, the S-phase checkpoint assay by measuring DNA synthesis in response to ionizing radiation, and the G2/M checkpoint assay by quantitating histone H3 phosphorylation after ionizing radiation.

Authors
Xu, B; Kastan, MB
MLA Citation
Xu, B, and Kastan, MB. "Analyzing cell cycle checkpoints after ionizing radiation." Methods Mol Biol 281 (2004): 283-292.
PMID
15220537
Source
pubmed
Published In
Methods in molecular biology (Clifton, N.J.)
Volume
281
Publish Date
2004
Start Page
283
End Page
292
DOI
10.1385/1-59259-811-0:283

HSV-1 amplicon vector-mediated expression of ATM cDNA and correction of the ataxia-telangiectasia cellular phenotype.

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by neurodegeneration, immunodeficiency, cancer predisposition, genome instability, and radiation sensitivity. Previous research has shown that it is possible to correct the hereditary deficiency A-T by DNA transfection in cell culture, but the large size of the ATM cDNA (9 kb) limits the use of many vector types for gene replacement. HSV-1 amplicon vectors provide a means to deliver large genes to cells efficiently and without toxicity. In this study, the FLAG-tagged cDNA for human ATM was inserted into an HSV-1 amplicon under control of the CMV promoter (designated as HGC-ATM). FLAG-ATM expression was confirmed in 293T/17 cells and human A-T fibroblasts (GM9607) after transduction, by immunoprecipitation, Western analysis, and immunocytochemistry. Functional recovery was assessed by two independent assays. First, in vitro kinase assay showed that vector-derived ATM in GM9607 cells could successfully phosphorylate wt p53 using recombinant GST-p53(1-101). Second, in A-T cells infected with the HGC-ATM vector, the extent of accumulation in G2/M phase at 24 h postirradiation was similar to that observed in cells with wild-type endogenous ATM and lower than that observed in A-T cells infected with a control vector. Thus, these vectors provide a tool to test the feasibility of HSV-amplicons as gene therapy vectors for A-T.

Authors
Cortés, ML; Bakkenist, CJ; Di Maria, MV; Kastan, MB; Breakefield, XO
MLA Citation
Cortés, ML, Bakkenist, CJ, Di Maria, MV, Kastan, MB, and Breakefield, XO. "HSV-1 amplicon vector-mediated expression of ATM cDNA and correction of the ataxia-telangiectasia cellular phenotype." Gene Ther 10.16 (August 2003): 1321-1327.
PMID
12883528
Source
pubmed
Published In
Gene Therapy
Volume
10
Issue
16
Publish Date
2003
Start Page
1321
End Page
1327
DOI
10.1038/sj.gt.3301996

Distinct functions of Nijmegen breakage syndrome in ataxia telangiectasia mutated-dependent responses to DNA damage.

Phosphorylation of NBS1, the product of the gene mutated in Nijmegen breakage syndrome (NBS), by ataxia telangiectasia mutated (ATM), the product of the gene mutated in ataxia telangiectasia, is required for activation of the S phase checkpoint in response to ionizing radiation (IR). However, NBS1 is also thought to play additional roles in the cellular response to DNA damage. To clarify these additional functions of NBS1, we generated NBS cell lines stably expressing various NBS1 mutants from retroviral vectors. The ATM-dependent activation of CHK2 by IR was defective in NBS cells but was restored by ectopic expression of wild-type NBS1. The defects in ATM-dependent activation of CHK2, S phase checkpoint control, IR-induced nuclear focus formation, and radiation sensitivity apparent in NBS cells were not corrected by expression of NBS1 mutants that lack an intact MRE11 binding domain, suggesting that formation of the NBS1-MRE11-RAD50 complex is required for the corresponding normal phenotypes. Expression of NBS1 proteins with mutated ATM-targeted phosphorylation sites (serines 278 or 343) did not restore S phase checkpoint control but did restore the ability of IR to activate CHK2 and to induce nuclear focus formation and normalized the radiation sensitivity of NBS cells. Expression of NBS1 containing mutations in the forkhead-associated or BRCA1 COOH terminus domains did not correct the defects in radiation sensitivity or nuclear focus formation but did restore S phase checkpoint control in NBS cells. Together, these data demonstrate that multiple functional domains of NBS1 are required for ATM-dependent activation of CHK2, nuclear focus formation, S phase checkpoint control, and cell survival after exposure to IR.

Authors
Lee, JH; Xu, B; Lee, C-H; Ahn, J-Y; Song, MS; Lee, H; Canman, CE; Lee, J-S; Kastan, MB; Lim, D-S
MLA Citation
Lee, JH, Xu, B, Lee, C-H, Ahn, J-Y, Song, MS, Lee, H, Canman, CE, Lee, J-S, Kastan, MB, and Lim, D-S. "Distinct functions of Nijmegen breakage syndrome in ataxia telangiectasia mutated-dependent responses to DNA damage." Mol Cancer Res 1.9 (July 2003): 674-681.
PMID
12861053
Source
pubmed
Published In
Molecular cancer research : MCR
Volume
1
Issue
9
Publish Date
2003
Start Page
674
End Page
681

DNA damage activates ATM through intermolecular autophosphorylation and dimer dissociation.

The ATM protein kinase, mutations of which are associated with the human disease ataxia-telangiectasia, mediates responses to ionizing radiation in mammalian cells. Here we show that ATM is held inactive in unirradiated cells as a dimer or higher-order multimer, with the kinase domain bound to a region surrounding serine 1981 that is contained within the previously described 'FAT' domain. Cellular irradiation induces rapid intermolecular autophosphorylation of serine 1981 that causes dimer dissociation and initiates cellular ATM kinase activity. Most ATM molecules in the cell are rapidly phosphorylated on this site after doses of radiation as low as 0.5 Gy, and binding of a phosphospecific antibody is detectable after the introduction of only a few DNA double-strand breaks in the cell. Activation of the ATM kinase seems to be an initiating event in cellular responses to irradiation, and our data indicate that ATM activation is not dependent on direct binding to DNA strand breaks, but may result from changes in the structure of chromatin.

Authors
Bakkenist, CJ; Kastan, MB
MLA Citation
Bakkenist, CJ, and Kastan, MB. "DNA damage activates ATM through intermolecular autophosphorylation and dimer dissociation." Nature 421.6922 (January 30, 2003): 499-506.
PMID
12556884
Source
pubmed
Published In
Nature
Volume
421
Issue
6922
Publish Date
2003
Start Page
499
End Page
506
DOI
10.1038/nature01368

Parc-ing p53 in the cytoplasm.

Nikolaev et al. (this issue of Cell) report the identification of a parkin-like protein, Parc, and its role in anchoring the tumor suppressor protein p53 in the cytoplasm reveals yet another level of control of p53 function. Regulation of the subcellular localization of p53 by Parc may serve as a novel target in treatment of certain types of tumors.

Authors
Kastan, MB; Zambetti, GP
MLA Citation
Kastan, MB, and Zambetti, GP. "Parc-ing p53 in the cytoplasm." Cell 112.1 (January 10, 2003): 1-2.
PMID
12526785
Source
pubmed
Published In
Cell
Volume
112
Issue
1
Publish Date
2003
Start Page
1
End Page
2

Molecular Cancer Research: A Note from the Editor

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Molecular Cancer Research: A Note from the Editor." Molecular Cancer Research 1.14 (2003): vi-.
Source
scival
Published In
Molecular Cancer Research
Volume
1
Issue
14
Publish Date
2003
Start Page
vi

Interaction of FANCD2 and NBS1 in the DNA damage response.

Fanconi anaemia (FA) and Nijmegen breakage syndrome (NBS) are autosomal recessive chromosome instability syndromes with distinct clinical phenotypes. Cells from individuals affected with FA are hypersensitive to mitomycin C (MMC), and cells from those with NBS are hypersensitive to ionizing radiation. Here we report that both NBS cell lines and individuals with NBS are hypersensitive to MMC, indicating that there may be functional linkage between FA and NBS. In wild-type cells, MMC activates the colocalization of the FA subtype D2 protein (FANCD2) and NBS1 protein in subnuclear foci. Ionizing radiation activates the ataxia telangiectasia kinase (ATM)-dependent and NBS1-dependent phosphorylation of FANCD2, resulting in an S-phase checkpoint. NBS1 and FANCD2 therefore cooperate in two distinct cellular functions, one involved in the DNA crosslink response and one involved in the S-phase checkpoint response.

Authors
Nakanishi, K; Taniguchi, T; Ranganathan, V; New, HV; Moreau, LA; Stotsky, M; Mathew, CG; Kastan, MB; Weaver, DT; D'Andrea, AD
MLA Citation
Nakanishi, K, Taniguchi, T, Ranganathan, V, New, HV, Moreau, LA, Stotsky, M, Mathew, CG, Kastan, MB, Weaver, DT, and D'Andrea, AD. "Interaction of FANCD2 and NBS1 in the DNA damage response." Nat Cell Biol 4.12 (December 2002): 913-920.
PMID
12447395
Source
pubmed
Published In
Nature Cell Biology
Volume
4
Issue
12
Publish Date
2002
Start Page
913
End Page
920
DOI
10.1038/ncb879

BRCA1 deficient cells have increased fragile site expression that is complemented by wild type BRCA1.

Authors
Arlt, MF; Durkin, SG; Casper, AM; Kastan, MB; Glover, TW
MLA Citation
Arlt, MF, Durkin, SG, Casper, AM, Kastan, MB, and Glover, TW. "BRCA1 deficient cells have increased fragile site expression that is complemented by wild type BRCA1." October 2002.
Source
wos-lite
Published In
The American Journal of Human Genetics
Volume
71
Issue
4
Publish Date
2002
Start Page
181
End Page
181

Phosphorylation of serine 1387 in Brca1 is specifically required for the Atm-mediated S-phase checkpoint after ionizing irradiation.

Although it is well established that inheritance of mutations in the Brca1 gene significantly increases the chances of developing breast or ovarian cancers, the mechanisms underlying this specific tumor susceptibility remain to be clarified. It is clear that one of the roles of the Brca1 protein is to facilitate cellular responses to DNA damage. We recently reported that Brca1 function is required for appropriate cell cycle arrests after ionizing irradiation in both the S-phase and the G2 phase of the cell cycle. We also found that mutation of serine 1423 in Brca1, a target of Atm phosphorylation, abrogates the G2-M checkpoint but not the ionizing irradiation-induced S-phase checkpoint. Here we demonstrate that mutation of serine 1387 in Brca1, another target of Atm phosphorylation, conversely abrogates the radiation-induced S-phase arrest but does not affect the G2-M checkpoint. Thus, these two posttranslational modifications of Brca1 have two distinct functional roles in the protein. In addition, although mutation of this site abrogates the ionizing irradiation-induced S-phase arrest, it does not adversely affect cell survival after irradiation. This demonstrates that loss of this checkpoint function by itself does not affect cell survival and suggests that some other function of Brca1 alters cell survival after DNA damage.

Authors
Xu, B; O'Donnell, AH; Kim, S-T; Kastan, MB
MLA Citation
Xu, B, O'Donnell, AH, Kim, S-T, and Kastan, MB. "Phosphorylation of serine 1387 in Brca1 is specifically required for the Atm-mediated S-phase checkpoint after ionizing irradiation." Cancer Res 62.16 (August 15, 2002): 4588-4591.
PMID
12183412
Source
pubmed
Published In
Cancer Research
Volume
62
Issue
16
Publish Date
2002
Start Page
4588
End Page
4591

Convergence of the fanconi anemia and ataxia telangiectasia signaling pathways.

Fanconi anemia (FA) and ataxia telangiectasia (AT) are clinically distinct autosomal recessive disorders characterized by spontaneous chromosome breakage and hematological cancers. FA cells are hypersensitive to mitomycin C (MMC), while AT cells are hypersensitive to ionizing radiation (IR). Here, we identify the Fanconi anemia protein, FANCD2, as a link between the FA and ATM damage response pathways. ATM phosphorylates FANCD2 on serine 222 in vitro. This site is also phosphorylated in vivo in an ATM-dependent manner following IR. Phosphorylation of FANCD2 is required for activation of an S phase checkpoint. The ATM-dependent phosphorylation of FANCD2 on S222 and the FA pathway-dependent monoubiquitination of FANCD2 on K561 are independent posttranslational modifications regulating discrete cellular signaling pathways. Biallelic disruption of FANCD2 results in both MMC and IR hypersensitivity.

Authors
Taniguchi, T; Garcia-Higuera, I; Xu, B; Andreassen, PR; Gregory, RC; Kim, S-T; Lane, WS; Kastan, MB; D'Andrea, AD
MLA Citation
Taniguchi, T, Garcia-Higuera, I, Xu, B, Andreassen, PR, Gregory, RC, Kim, S-T, Lane, WS, Kastan, MB, and D'Andrea, AD. "Convergence of the fanconi anemia and ataxia telangiectasia signaling pathways." Cell 109.4 (May 17, 2002): 459-472.
PMID
12086603
Source
pubmed
Published In
Cell
Volume
109
Issue
4
Publish Date
2002
Start Page
459
End Page
472

Involvement of the cohesin protein, Smc1, in Atm-dependent and independent responses to DNA damage.

Structural maintenance of chromosomes (SMC) proteins play important roles in sister chromatid cohesion, chromosome condensation, sex-chromosome dosage compensation, and DNA recombination and repair. Protein complexes containing heterodimers of the Smc1 and Smc3 proteins have been implicated specifically in both sister chromatid cohesion and DNA recombination. Here, we show that the protein kinase, Atm, which belongs to a family of phosphatidylinositol 3-kinases that regulate cell cycle checkpoints and DNA recombination and repair, phosphorylates Smc1 protein after ionizing irradiation. Atm phosphorylates Smc1 on serines 957 and 966 in vitro and in vivo, and expression of an Smc1 protein mutated at these phosphorylation sites abrogates the ionizing irradiation-induced S phase cell cycle checkpoint. Optimal phosphorylation of these sites in Smc1 after ionizing irradiation also requires the presence of the Atm substrates Nbs1 and Brca1. These same sites in Smc1 are phosphorylated after treatment with UV irradiation or hydroxyurea in an Atm-independent manner, thus demonstrating that another kinase must be involved in responses to these cellular stresses. Yeast containing hypomorphic mutations in SMC1 and human cells overexpressing Smc1 mutated at both of these phosphorylation sites exhibit decreased survival following ionizing irradiation. These results demonstrate that Smc1 participates in cellular responses to DNA damage and link Smc1 to the Atm signal transduction pathway.

Authors
Kim, S-T; Xu, B; Kastan, MB
MLA Citation
Kim, S-T, Xu, B, and Kastan, MB. "Involvement of the cohesin protein, Smc1, in Atm-dependent and independent responses to DNA damage." Genes Dev 16.5 (March 1, 2002): 560-570.
PMID
11877376
Source
pubmed
Published In
Genes & development
Volume
16
Issue
5
Publish Date
2002
Start Page
560
End Page
570
DOI
10.1101/gad.970602

Two molecularly distinct G(2)/M checkpoints are induced by ionizing irradiation.

Cell cycle checkpoints are among the multiple mechanisms that eukaryotic cells possess to maintain genomic integrity and minimize tumorigenesis. Ionizing irradiation (IR) induces measurable arrests in the G(1), S, and G(2) phases of the mammalian cell cycle, and the ATM (ataxia telangiectasia mutated) protein plays a role in initiating checkpoint pathways in all three of these cell cycle phases. However, cells lacking ATM function exhibit both a defective G(2) checkpoint and a prolonged G(2) arrest after IR, suggesting the existence of different types of G(2) arrest. Two molecularly distinct G(2)/M checkpoints were identified, and the critical importance of the choice of G(2)/M checkpoint assay was demonstrated. The first of these G(2)/M checkpoints occurs early after IR, is very transient, is ATM dependent and dose independent (between 1 and 10 Gy), and represents the failure of cells which had been in G(2) at the time of irradiation to progress into mitosis. Cell cycle assays that can distinguish mitotic cells from G(2) cells must be used to assess this arrest. In contrast, G(2)/M accumulation, typically assessed by propidium iodide staining, begins to be measurable only several hours after IR, is ATM independent, is dose dependent, and represents the accumulation of cells that had been in earlier phases of the cell cycle at the time of exposure to radiation. G(2)/M accumulation after IR is not affected by the early G(2)/M checkpoint and is enhanced in cells lacking the IR-induced S-phase checkpoint, such as those lacking Nbs1 or Brca1 function, because of a prolonged G(2) arrest of cells that had been in S phase at the time of irradiation. Finally, neither the S-phase checkpoint nor the G(2) checkpoints appear to affect survival following irradiation. Thus, two different G(2) arrest mechanisms are present in mammalian cells, and the type of cell cycle checkpoint assay to be used in experimental investigation must be thoughtfully selected.

Authors
Xu, B; Kim, S-T; Lim, D-S; Kastan, MB
MLA Citation
Xu, B, Kim, S-T, Lim, D-S, and Kastan, MB. "Two molecularly distinct G(2)/M checkpoints are induced by ionizing irradiation." Mol Cell Biol 22.4 (February 2002): 1049-1059.
PMID
11809797
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
22
Issue
4
Publish Date
2002
Start Page
1049
End Page
1059

Welcome to molecular cancer research

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Welcome to molecular cancer research." Molecular Cancer Research 1.1 (2002): 1--.
Source
scival
Published In
Molecular Cancer Research
Volume
1
Issue
1
Publish Date
2002
Start Page
1-

Molecular interaction of the Fanconi Anemia (FA) and Ataxia Telangiectasia (AT) pathways.

Authors
Taniguchi, T; Garcia-Higuera, I; Lane, WS; Kim, ST; Xu, B; Kastan, MB; D'Andrea, AD
MLA Citation
Taniguchi, T, Garcia-Higuera, I, Lane, WS, Kim, ST, Xu, B, Kastan, MB, and D'Andrea, AD. "Molecular interaction of the Fanconi Anemia (FA) and Ataxia Telangiectasia (AT) pathways." BLOOD 98.11 (November 16, 2001): 782A-782A.
Source
wos-lite
Published In
Blood
Volume
98
Issue
11
Publish Date
2001
Start Page
782A
End Page
782A

Differential activation of the Fanconi Anemia protein, FANCD2, by monoubiquitination and phosphorylation

Authors
D'Andrea, AD; Garcia-Higuera, I; Lane, WS; Xu, B; Kastan, MB; Taniguchi, T
MLA Citation
D'Andrea, AD, Garcia-Higuera, I, Lane, WS, Xu, B, Kastan, MB, and Taniguchi, T. "Differential activation of the Fanconi Anemia protein, FANCD2, by monoubiquitination and phosphorylation." MOLECULAR BIOLOGY OF THE CELL 12 (November 2001): 5A-6A.
Source
wos-lite
Published In
Molecular Biology of the Cell
Volume
12
Publish Date
2001
Start Page
5A
End Page
6A

ATM-dependent phosphorylation of Mdm2 on serine 395: role in p53 activation by DNA damage.

The p53 tumor suppressor protein, a key regulator of cellular responses to genotoxic stress, is stabilized and activated after DNA damage. The rapid activation of p53 by ionizing radiation and radiomimetic agents is largely dependent on the ATM kinase. p53 is phosphorylated by ATM shortly after DNA damage, resulting in enhanced stability and activity of p53. The Mdm2 oncoprotein is a pivotal negative regulator of p53. In response to ionizing radiation and radiomimetic drugs, Mdm2 undergoes rapid ATM-dependent phosphorylation prior to p53 accumulation. This results in a decrease in its reactivity with the 2A10 monoclonal antibody. Phage display analysis identified a consensus 2A10 recognition sequence, possessing the core motif DYS. Unexpectedly, this motif appears twice within the human Mdm2 molecule, at positions corresponding to residues 258-260 and 393-395. Both putative 2A10 epitopes are highly conserved and encompass potential phosphorylation sites. Serine 395, residing within the carboxy-terminal 2A10 epitope, is the major target on Mdm2 for phosphorylation by ATM in vitro. Mutational analysis supports the conclusion that Mdm2 undergoes ATM-dependent phosphorylation on serine 395 in vivo in response to DNA damage. The data further suggests that phosphorylated Mdm2 may be less capable of promoting the nucleo-cytoplasmic shuttling of p53 and its subsequent degradation, thereby enabling p53 accumulation. Our findings imply that activation of p53 by DNA damage is achieved, in part, through attenuation of the p53-inhibitory potential of Mdm2.

Authors
Maya, R; Balass, M; Kim, ST; Shkedy, D; Leal, JF; Shifman, O; Moas, M; Buschmann, T; Ronai, Z; Shiloh, Y; Kastan, MB; Katzir, E; Oren, M
MLA Citation
Maya, R, Balass, M, Kim, ST, Shkedy, D, Leal, JF, Shifman, O, Moas, M, Buschmann, T, Ronai, Z, Shiloh, Y, Kastan, MB, Katzir, E, and Oren, M. "ATM-dependent phosphorylation of Mdm2 on serine 395: role in p53 activation by DNA damage." Genes Dev 15.9 (May 1, 2001): 1067-1077.
PMID
11331603
Source
pubmed
Published In
Genes & development
Volume
15
Issue
9
Publish Date
2001
Start Page
1067
End Page
1077
DOI
10.1101/gad.886901

Involvement of Brca1 in S-phase and G(2)-phase checkpoints after ionizing irradiation.

Cell cycle arrests in the G(1), S, and G(2) phases occur in mammalian cells after ionizing irradiation and appear to protect cells from permanent genetic damage and transformation. Though Brca1 clearly participates in cellular responses to ionizing radiation (IR), conflicting conclusions have been drawn about whether Brca1 plays a direct role in cell cycle checkpoints. Normal Nbs1 function is required for the IR-induced S-phase checkpoint, but whether Nbs1 has a definitive role in the G(2)/M checkpoint has not been established. Here we show that Atm and Brca1 are required for both the S-phase and G(2) arrests induced by ionizing irradiation while Nbs1 is required only for the S-phase arrest. We also found that mutation of serine 1423 in Brca1, a target for phosphorylation by Atm, abolished the ability of Brca1 to mediate the G(2)/M checkpoint but did not affect its S-phase function. These results clarify the checkpoint roles for each of these three gene products, demonstrate that control of cell cycle arrests must now be included among the important functions of Brca1 in cellular responses to DNA damage, and suggest that Atm phosphorylation of Brca1 is required for the G(2)/M checkpoint.

Authors
Xu, B; Kim St, ; Kastan, MB
MLA Citation
Xu, B, Kim St, , and Kastan, MB. "Involvement of Brca1 in S-phase and G(2)-phase checkpoints after ionizing irradiation." Mol Cell Biol 21.10 (May 2001): 3445-3450.
PMID
11313470
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
21
Issue
10
Publish Date
2001
Start Page
3445
End Page
3450
DOI
10.1128/MCB.21.10.3445-3450.2001

Cell cycle. Checking two steps.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Cell cycle. Checking two steps." Nature 410.6830 (April 12, 2001): 766-767.
PMID
11298430
Source
pubmed
Published In
Nature
Volume
410
Issue
6830
Publish Date
2001
Start Page
766
End Page
767
DOI
10.1038/35071218

ATM--a key determinant of multiple cellular responses to irradiation.

Ataxia-telangiectasia is a rare clinical disorder manifesting a variety of different abnormalities, including progressive neurodegeneration, increased cancer incidence, immune deficiency, sterility, and extreme radiosensitivity. Recent studies have demonstrated that the defective gene product in this disease, ATM, is a protein kinase. The identification of several different substrates for this kinase is beginning to explain the wide array of different physiologic abnormalities that occur when this gene product is dysfunctional. Since the ATM protein is a critical signaling molecule in the cellular response to ionizing irradiation, the identification of these substrates also results in elucidation of the steps involved in a number of different cellular signaling pathways initiated by irradiation. Such insights also result in the identification of potential new targets for enhancing the efficacy of radiation therapy.

Authors
Kastan, MB; Lim, DS; Kim, ST; Yang, D
MLA Citation
Kastan, MB, Lim, DS, Kim, ST, and Yang, D. "ATM--a key determinant of multiple cellular responses to irradiation." Acta Oncol 40.6 (2001): 686-688. (Review)
PMID
11765061
Source
pubmed
Published In
Acta Oncologica (Informa)
Volume
40
Issue
6
Publish Date
2001
Start Page
686
End Page
688

Glioblastoma-related gene mutations and over-expression of functional epidermal growth factor receptors in SKMG-3 glioma cells

Amplification of the epidermal growth factor receptor (EGFR) gene is found in about 40% of glioblastomas (GBMs) but is rarely detected in GBM cell lines. We confirmed that the exceptional SKMG-3 GBM cell line retained amplified EGFR genes in vitro, and found that these sequences were concentrated on extra-chromosomal DNA particles similar to double-minute chromosomes. The cells contained two other gene mutations that are associated with high-grade astrocytic tumors: extra-chromosomal amplification of the cyclin-dependent kinase-4 (CDK4) gene and a homozygous mutation within the PTEN tumor suppressor gene. Immunoblots revealed very high levels of EGFR, moderately increased expression of CDK4, and no detectable PTEN protein. The over-expressed SKMG-3 EGFRs responded to exogenous ligand and resembled normal rather than mutant receptors. A heterozygous mutation of the p53 gene (p53R282W) correlated with failure of radiation to induce the expression of cyclin-dependent kinase inhibitor p21waf1 or an early G1 cell cycle arrest. Although each of these gene mutations occurs in GBMs, SKMG-3 cells had an unusual genotype in that a p53 gene mutation co-existed with amplified EGFR genes. Nonetheless, the SKMG-3 cell line can be exploited as a model to study how oncogenic EGFR signals in GBM cells interact with over-expressed CDK4 and loss of PTEN to confer the malignant phenotype.

Authors
Thomas, C; Ely, G; James, CD; Jenkins, R; Kastan, M; Jedlicka, A; Burger, P; Wharen, R
MLA Citation
Thomas, C, Ely, G, James, CD, Jenkins, R, Kastan, M, Jedlicka, A, Burger, P, and Wharen, R. "Glioblastoma-related gene mutations and over-expression of functional epidermal growth factor receptors in SKMG-3 glioma cells." Acta Neuropathologica 101.6 (2001): 605-615.
PMID
11515790
Source
scival
Published In
Acta Neuropathologica
Volume
101
Issue
6
Publish Date
2001
Start Page
605
End Page
615

Regulation of p53 by Hypoxia: Dissociation of transcriptional repression and apoptosis from p53-dependent transactivation

Hypoxic stress, like DNA damage, induces p53 protein accumulation and p53-dependent apoptosis in oncogenically transformed cells. Unlike DNA damage, hypoxia does not induce p53-dependent cell cycle arrest, suggesting that p53 activity is differentially regulated by these two stresses. Here we report that hypoxia induces p53 protein accumulation, but in contrast to DNA damage, hypoxia fails to induce endogenous downstream p53 effector mRNAs and proteins. Hypoxia does not inhibit the induction of p53 target genes by ionizing radiation, indicating that p53-dependent transactivation requires a DNA damage-inducible signal that is lacking under hypoxic treatment alone. At the molecular level, DNA damage induces the interaction of p53 with the transcriptional activator p300 as well as with the transcriptional corepressor mSin3A. In contrast, hypoxia primarily induces an interaction of p53 with mSin3A, but not with p300. Pretreatment of cells with an inhibitor of histone deacetylases that relieves transcriptional repression resulted in a significant reduction of p53-dependent transrepression and hypoxia-induced apoptosis. These results led us to propose a model in which different cellular pools of p53 can modulate transcriptional activity through interactions with transcriptional coactivators or corepressors. Genotoxic stress induces both kinds of interactions, whereas stresses that lack a DNA damage component as exemplified by hypoxia primarily induce interaction with corepressors. However, inhibition of either type of interaction can result in diminished apoptotic activity.

Authors
Koumenis, C; Alarcon, R; Hammond, E; Sutphin, P; Hoffman, W; Murphy, M; Derr, J; Taya, Y; Lowe, SW; Kastan, M; Giaccia, A
MLA Citation
Koumenis, C, Alarcon, R, Hammond, E, Sutphin, P, Hoffman, W, Murphy, M, Derr, J, Taya, Y, Lowe, SW, Kastan, M, and Giaccia, A. "Regulation of p53 by Hypoxia: Dissociation of transcriptional repression and apoptosis from p53-dependent transactivation." Molecular and Cellular Biology 21.4 (2001): 1297-1310.
PMID
11158315
Source
scival
Published In
Molecular and Cellular Biology
Volume
21
Issue
4
Publish Date
2001
Start Page
1297
End Page
1310
DOI
10.1128/MCB.21.4.1297-1310.2001

ATM: genome stability, neuronal development, and cancer cross paths.

One of the cornerstones of the web of signaling pathways governing cellular life and differentiation is the DNA damage response. It spans a complex network of pathways, ranging from DNA repair to modulation of numerous processes in the cell. DNA double-strand breaks (DSBs), which are formed as a result of genotoxic stress or normal recombinational processes, are extremely lethal lesions that rapidly mobilize this intricate defense system. The master controller that pilots cellular responses to DSBs is the ATM protein kinase, which turns on this network by phosphorylating key players in its various branches. ATM is the protein product of the gene mutated in the human genetic disorder ataxia-telangiectasia (A-T), which is characterized by neuronal degeneration, immunodeficiency, sterility, genomic instability, cancer predisposition, and radiation sensitivity. The clinical and cellular phenotype of A-T attests to the numerous roles of ATM, on the one hand, and to the link between the DNA damage response and developmental processes on the other hand. Recent studies of this protein and its effectors, combined with a thorough investigation of animal models of A-T, have led to new insights into the mode of action of this master controller of the DNA damage response. The evidence that ATM is involved in signaling pathways other than those related to damage response, particularly ones relating to cellular growth and differentiation, reinforces the multifaceted nature of this protein, in which genome stability, developmental processes, and cancer cross paths.

Authors
Shiloh, Y; Kastan, MB
MLA Citation
Shiloh, Y, and Kastan, MB. "ATM: genome stability, neuronal development, and cancer cross paths." Adv Cancer Res 83 (2001): 209-254. (Review)
PMID
11665719
Source
pubmed
Published In
Advances in cancer research
Volume
83
Publish Date
2001
Start Page
209
End Page
254

The many substrates and functions of ATM.

As its name suggests, the ATM--'ataxia-telangiectasia, mutated'--gene is responsible for the rare disorder ataxia-telangiectasia. Patients show various abnormalities, mainly in their responses to DNA damage, but also in other cellular processes. Although it is hard to understand how a single gene product is involved in so many physiological processes, a clear picture is starting to emerge.

Authors
Kastan, MB; Lim, DS
MLA Citation
Kastan, MB, and Lim, DS. "The many substrates and functions of ATM." Nat Rev Mol Cell Biol 1.3 (December 2000): 179-186. (Review)
PMID
11252893
Source
pubmed
Published In
Nature Reviews Molecular Cell Biology
Volume
1
Issue
3
Publish Date
2000
Start Page
179
End Page
186
DOI
10.1038/35043058

Participation of ATM in insulin signalling through phosphorylation of eIF-4E-binding protein 1.

One of the critical responses to insulin treatment is the stimulation of protein synthesis through induced phosphorylation of the eIF-4E-binding protein 1 (4E-BP1), and the subsequent release of the translation initiation factor, eIF-4E. Here we report that ATM, the protein product of the ATM gene that is mutated in the disease ataxia telangiectasia, phosphorylates 4E-BP1 at Ser 111 in vitro and that insulin treatment induces phosphorylation of 4E-BP1 at Ser 111 in vivo in an ATM-dependent manner. In addition, insulin treatment of cells enhances the specific kinase activity of ATM. Cells lacking ATM kinase activity exhibit a significant decrease in the insulin-induced dissociation of 4E-BP1 from eIF-4E. These results suggest an unexpected role for ATM in an insulin-signalling pathway that controls translation initiation. Through this mechanism, a lack of ATM activity probably contributes to some of the metabolic abnormalities, such as poor growth and insulin resistance, reported in ataxia telangiectasia cells and patients with ataxia telangiectasia.

Authors
Yang, DQ; Kastan, MB
MLA Citation
Yang, DQ, and Kastan, MB. "Participation of ATM in insulin signalling through phosphorylation of eIF-4E-binding protein 1." Nat Cell Biol 2.12 (December 2000): 893-898.
PMID
11146653
Source
pubmed
Published In
Nature Cell Biology
Volume
2
Issue
12
Publish Date
2000
Start Page
893
End Page
898
DOI
10.1038/35046542

Cancer. A radical approach to treatment.

Authors
Cleveland, JL; Kastan, MB
MLA Citation
Cleveland, JL, and Kastan, MB. "Cancer. A radical approach to treatment." Nature 407.6802 (September 21, 2000): 309-311.
PMID
11014172
Source
pubmed
Published In
Nature
Volume
407
Issue
6802
Publish Date
2000
Start Page
309
End Page
311
DOI
10.1038/35030277

ATM phosphorylates p95/nbs1 in an S-phase checkpoint pathway.

The rare diseases ataxia-telangiectasia (AT), caused by mutations in the ATM gene, and Nijmegen breakage syndrome (NBS), with mutations in the p95/nbs1 gene, share a variety of phenotypic abnormalities such as chromosomal instability, radiation sensitivity and defects in cell-cycle checkpoints in response to ionizing radiation. The ATM gene encodes a protein kinase that is activated by ionizing radiation or radiomimetic drugs, whereas p95/nbs1 is part of a protein complex that is involved in responses to DNA double-strand breaks. Here, because of the similarities between AT and NBS, we evaluated the functional interactions between ATM and p95/nbs1. Activation of the ATM kinase by ionizing radiation and induction of ATM-dependent responses in NBS cells indicated that p95/nbs1 may not be required for signalling to ATM after ionizing radiation. However, p95/nbs1 was phosphorylated on serine 343 in an ATM-dependent manner in vitro and in vivo after ionizing radiation. A p95/nbs1 construct mutated at the ATM phosphorylation site abrogated an S-phase checkpoint induced by ionizing radiation in normal cells and failed to compensate for this functional deficiency in NBS cells. These observations link ATM and p95/nbs1 in a common signalling pathway and provide an explanation for phenotypic similarities in these two diseases.

Authors
Lim, DS; Kim, ST; Xu, B; Maser, RS; Lin, J; Petrini, JH; Kastan, MB
MLA Citation
Lim, DS, Kim, ST, Xu, B, Maser, RS, Lin, J, Petrini, JH, and Kastan, MB. "ATM phosphorylates p95/nbs1 in an S-phase checkpoint pathway." Nature 404.6778 (April 6, 2000): 613-617.
PMID
10766245
Source
pubmed
Published In
Nature
Volume
404
Issue
6778
Publish Date
2000
Start Page
613
End Page
617
DOI
10.1038/35007091

Ionizing radiation activates the ATM kinase throughout the cell cycle.

The ATM protein kinase is a critical intermediate in a number of cellular responses to ionizing irradiation (IR) and possibly other stresses. ATM dysfunction results in abnormal checkpoint responses in multiple phases of the cell cycle, including G1, S and G2. Though downstream targets of the ATM kinase are still being elucidated, it has been demonstrated that ATM acts upstream of p53 in a signal transduction pathway initiated by IR and can phosphorylate p53 at serine 15. The cell cycle stage-specificity of ATM activation and p53Ser15 phosphorylation was investigated in normal lymphoblastoid cell line (GM536). Ionizing radiation was found to enhance the kinase activity of ATM in all phases of the cell cycle. This enhanced activity was apparent immediately after treatment of cells with IR, but was not accompanied by a change in the abundance of the ATM protein. Since IR activates the ATM kinase in all phases of the cell cycle, DNA replication-dependent strand breaks are not required for this activation. Further, since p53 protein is not directly required for IR-induced S and G2-phase checkpoints, the ATM kinase likely has different functional targets in different phases of the cell cycle. These observations indicate that the ATM kinase is necessary primarily for the immediate response to DNA damage incurred in all phases of the cell cycle.

Authors
Pandita, TK; Lieberman, HB; Lim, DS; Dhar, S; Zheng, W; Taya, Y; Kastan, MB
MLA Citation
Pandita, TK, Lieberman, HB, Lim, DS, Dhar, S, Zheng, W, Taya, Y, and Kastan, MB. "Ionizing radiation activates the ATM kinase throughout the cell cycle." Oncogene 19.11 (March 9, 2000): 1386-1391.
PMID
10723129
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
19
Issue
11
Publish Date
2000
Start Page
1386
End Page
1391
DOI
10.1038/sj.onc.1203444

Multiple signaling pathways involving ATM.

Authors
Kastan, MB; Lim, DS; Kim, ST; Xu, B; Canman, C
MLA Citation
Kastan, MB, Lim, DS, Kim, ST, Xu, B, and Canman, C. "Multiple signaling pathways involving ATM." Cold Spring Harb Symp Quant Biol 65 (2000): 521-526. (Review)
PMID
12760069
Source
pubmed
Published In
Cold Spring Harbor Laboratory: Symposia on Quantitative Biology
Volume
65
Publish Date
2000
Start Page
521
End Page
526

Expression and assay of recombinant ATM.

Authors
Ziv, Y; Banin, S; Lim, DS; Canman, CE; Kastan, MB; Shiloh, Y
MLA Citation
Ziv, Y, Banin, S, Lim, DS, Canman, CE, Kastan, MB, and Shiloh, Y. "Expression and assay of recombinant ATM." Methods Mol Biol 99 (2000): 99-108. (Review)
PMID
10909080
Source
pubmed
Published In
Methods in molecular biology (Clifton, N.J.)
Volume
99
Publish Date
2000
Start Page
99
End Page
108
DOI
10.1385/1-59259-054-3:99

Roles of TP53 and ATM in radiation responses

Authors
Kastan, MB; Lim, DS; Kim, ST; Canman, CE
MLA Citation
Kastan, MB, Lim, DS, Kim, ST, and Canman, CE. "Roles of TP53 and ATM in radiation responses." 2000.
Source
wos-lite
Published In
RADIATION RESEARCH, VOL 2, CONGRESS PROCEEDINGS
Publish Date
2000
Start Page
413
End Page
415

Substrate specificities and identification of putative substrates of ATM kinase family members.

Ataxia telangiectasia mutated (ATM) phosphorylates p53 protein in response to ionizing radiation, but the complex phenotype of AT cells suggests that it must have other cellular substrates as well. To identify substrates for ATM and the related kinases ATR and DNA-PK, we optimized in vitro kinase assays and developed a rapid peptide screening method to determine general phosphorylation consensus sequences. ATM and ATR require Mn(2+), but not DNA ends or Ku proteins, for optimal in vitro activity while DNA-PKCs requires Mg(2+), DNA ends, and Ku proteins. From p53 peptide mutagenesis analysis, we found that the sequence S/TQ is a minimal essential requirement for all three kinases. In addition, hydrophobic amino acids and negatively charged amino acids immediately NH(2)-terminal to serine or threonine are positive determinants and positively charged amino acids in the region are negative determinants for substrate phosphorylation. We determined a general phosphorylation consensus sequence for ATM and identified putative in vitro targets by using glutathione S-transferase peptides as substrates. Putative ATM in vitro targets include p95/nibrin, Mre11, Brca1, Rad17, PTS, WRN, and ATM (S440) itself. Brca2, phosphatidylinositol 3-kinase, and DNA-5B peptides were phosphorylated specifically by ATR, and DNA Ligase IV is a specific in vitro substrate of DNA-PK.

Authors
Kim, ST; Lim, DS; Canman, CE; Kastan, MB
MLA Citation
Kim, ST, Lim, DS, Canman, CE, and Kastan, MB. "Substrate specificities and identification of putative substrates of ATM kinase family members." J Biol Chem 274.53 (December 31, 1999): 37538-37543.
PMID
10608806
Source
pubmed
Published In
The Journal of biological chemistry
Volume
274
Issue
53
Publish Date
1999
Start Page
37538
End Page
37543

Phenylbutyrate-induced G1 arrest and apoptosis in myeloid leukemia cells: structure-function analysis.

The aromatic fatty acid phenylbutyrate (PB) induces cytostasis, differentiation, and apoptosis in primary myeloid leukemic cells at clinically achievable concentrations. In the present study, we have investigated the structural and cellular basis for PB-induced cytostasis, using the ML-1 human myeloid leukemia cell line as a model system. PB induced a dose-dependent increase in cells in G1 with a corresponding decrease in cells in S-phase of the cell cycle. At comparable doses, PB induced expression of CD11b, indicating myeloid differentiation. At higher doses, the drug induced apoptosis. The antitumor activity was independent of the aromatic ring, as butyric acid (BA) was of equal or greater potency at producing these biological changes. In contrast, shortening of the fatty acid carbon chain length, as demonstrated with phenylacetate (PA), significantly diminished drug potency. Consistent with their effects on cell cycle, PB and BA, but not PA, induced the cyclin-dependent kinase inhibitor, p21(WAF1/CIP1), and led to the appearance of hypophosphorylated Rb, suggesting a role for p21(WAF1/CIP1) in PB-induced cytostasis. Therefore, it appears that the fatty acid moiety of PB, rather than its aromatic ring, is critical for its activity in myeloid leukemic cells. These data provide a potential mechanistic basis for the increased potency of PB over PA previously demonstrated in primary leukemic samples, and support the further clinical development of PB in the treatment of hematologic malignancies.

Authors
DiGiuseppe, JA; Weng, LJ; Yu, KH; Fu, S; Kastan, MB; Samid, D; Gore, SD
MLA Citation
DiGiuseppe, JA, Weng, LJ, Yu, KH, Fu, S, Kastan, MB, Samid, D, and Gore, SD. "Phenylbutyrate-induced G1 arrest and apoptosis in myeloid leukemia cells: structure-function analysis." Leukemia 13.8 (August 1999): 1243-1253.
PMID
10450753
Source
pubmed
Published In
Leukemia
Volume
13
Issue
8
Publish Date
1999
Start Page
1243
End Page
1253

Molecular determinants of sensitivity to antitumor agents.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Molecular determinants of sensitivity to antitumor agents." Biochim Biophys Acta 1424.1 (July 29, 1999): R37-R42.
PMID
10456034
Source
pubmed
Published In
Biochimica et Biophysica Acta: international journal of biochemistry and biophysics
Volume
1424
Issue
1
Publish Date
1999
Start Page
R37
End Page
R42

Caspase-3-dependent cleavage of Bcl-2 promotes release of cytochrome c.

Caspases are cysteine proteases that mediate apoptosis by proteolysis of specific substrates. Although many caspase substrates have been identified, for most substrates the physiologic caspase(s) required for cleavage is unknown. The Bcl-2 protein, which inhibits apoptosis, is cleaved at Asp-34 by caspases during apoptosis and by recombinant caspase-3 in vitro. In the present study, we show that endogenous caspase-3 is a physiologic caspase for Bcl-2. Apoptotic extracts from 293 cells cleave Bcl-2 but not Bax, even though Bax is cleaved to an 18-kDa fragment in SK-NSH cells treated with ionizing radiation. In contrast to Bcl-2, cleavage of Bax was only partially blocked by caspase inhibitors. Inhibitor profiles indicate that Bax may be cleaved by more than one type of noncaspase protease. Immunodepletion of caspase-3 from 293 extracts abolished cleavage of Bcl-2 and caspase-7, whereas immunodepletion of caspase-7 had no effect on Bcl-2 cleavage. Furthermore, MCF-7 cells, which lack caspase-3 expression, do not cleave Bcl-2 following staurosporine-induced cell death. However, transient transfection of caspase-3 into MCF-7 cells restores Bcl-2 cleavage after staurosporine treatment. These results demonstrate that in these models of apoptosis, specific cleavage of Bcl-2 requires activation of caspase-3. When the pro-apoptotic caspase cleavage fragment of Bcl-2 is transfected into baby hamster kidney cells, it localizes to mitochondria and causes the release of cytochrome c into the cytosol. Therefore, caspase-3-dependent cleavage of Bcl-2 appears to promote further caspase activation as part of a positive feedback loop for executing the cell.

Authors
Kirsch, DG; Doseff, A; Chau, BN; Lim, DS; de Souza-Pinto, NC; Hansford, R; Kastan, MB; Lazebnik, YA; Hardwick, JM
MLA Citation
Kirsch, DG, Doseff, A, Chau, BN, Lim, DS, de Souza-Pinto, NC, Hansford, R, Kastan, MB, Lazebnik, YA, and Hardwick, JM. "Caspase-3-dependent cleavage of Bcl-2 promotes release of cytochrome c." J Biol Chem 274.30 (July 23, 1999): 21155-21161.
PMID
10409669
Source
pubmed
Published In
The Journal of biological chemistry
Volume
274
Issue
30
Publish Date
1999
Start Page
21155
End Page
21161

Cytoprotective effects of hematopoietic growth factors on primary human acute myeloid leukemias are not mediated through changes in BCL-2, bax, or p21WAF1/CIP1.

BACKGROUND: Hematopoietic growth factors (HGF) can suppress chemotherapy-induced programmed cell death (apoptosis) in hematopoietic cells. Although HGF can modulate the expression of apoptosis-regulatory genes, including bcl-2, bax, and p21WAF1/CIP1 in cell lines, few data address whether HGF regulate the expression of these proteins in primary acute myeloid leukemia (AML). MATERIALS AND METHODS: We evaluated the expression of bcl-2, bax, and p21WAF1/CIP1 in primary samples from patients with AML in the presence and absence of HGF. The potential association of HGF-induced changes in the levels of these proteins with inhibition of chemotherapy-induced apoptosis was further investigated. RESULTS: While a combination of steel factor (SF) and PIXY321 inhibited etoposide-induced apoptosis in 8/11 primary AML samples studied, Bcl-2 and bax protein levels were unaffected by exposure to HGF and/or etoposide. In contrast, HGF enhanced basal and etoposide-induced p21WAF1/CIP1 protein levels in 9/11 and 7/11 of the cases, respectively. In several cases, inhibition of apoptosis by HGF was seen without up-regulation of p21WAF1/CIP1 levels, suggesting that modulation of p21WAF1/CIP1 is not required for HGF-mediated inhibition of apoptosis. CONCLUSIONS: These data indicate that HGF-mediated inhibition of chemotherapy-induced apoptosis in primary AML samples is not mediated through changes in Bcl-2, bax, and p21WAF1/CIP1 protein levels.

Authors
DiGiuseppe, JA; Kastan, MB; Weng, LJ; Gore, SD
MLA Citation
DiGiuseppe, JA, Kastan, MB, Weng, LJ, and Gore, SD. "Cytoprotective effects of hematopoietic growth factors on primary human acute myeloid leukemias are not mediated through changes in BCL-2, bax, or p21WAF1/CIP1." In Vivo 13.1 (January 1999): 1-6.
PMID
10218124
Source
pubmed
Published In
In vivo (Athens, Greece)
Volume
13
Issue
1
Publish Date
1999
Start Page
1
End Page
6

Loss of atm radiosensitizes multiple p53 null tissues.

An unusual clinical finding in ataxia-telangiectasia, a human disorder caused by mutations in atm, is exquisite sensitivity to gamma irradiation. By contrast, homozygous deletion of p53 is marked by radiation resistance in certain tissue compartments. Previous studies (A. J. Levine, Cell, 88: 323-331, 1997) have shown that, in vitro, p53-deficient bone marrow cells are resistant to gamma irradiation. Furthermore, the gastrointestinal radiosensitization engendered by the loss of atm has recently been shown (C. H. Westphal et al., Nat. Genet., 16: 397-401, 1997) to be independent of p53. Expanding on previous work, we have looked at in vivo bone marrow resistance in p53-deficient mice. Our results indicate that inbred FVB strain p53 null mice survive lethal irradiation doses because of bone marrow resistance. Moreover, the deletion of atm radiosensitizes even p53 null bone marrow and mouse embryonic fibroblast cells. The results presented here argue that the loss of atm radiosensitizes multiple tissues in a p53-independent manner. Hence, functional inhibition of atm in p53 null and p53 wild-type human tumors may be a useful adjunct to gamma irradiation-based antitumor therapy.

Authors
Westphal, CH; Hoyes, KP; Canman, CE; Huang, X; Kastan, MB; Hendry, JH; Leder, P
MLA Citation
Westphal, CH, Hoyes, KP, Canman, CE, Huang, X, Kastan, MB, Hendry, JH, and Leder, P. "Loss of atm radiosensitizes multiple p53 null tissues." Cancer Res 58.24 (December 15, 1998): 5637-5639.
PMID
9865712
Source
pubmed
Published In
Cancer Research
Volume
58
Issue
24
Publish Date
1998
Start Page
5637
End Page
5639

Defective potassium currents in ataxia telangiectasia fibroblasts.

Similarities exist between the progressive cerebellar ataxia in ataxia telangiectasia (AT) patients and a number of neurodegenerative diseases in both mouse and man involving specific mutations in ion channels and/or ion channel activity. These relationships led us to investigate the possibility of defective ion channel activity in AT cells. We examined changes in the membrane potential of AT fibroblasts in response to extracellular cation addition and found that the ability of AT fibroblasts to depolarize in response to increasing concentrations of extracellular K+ is significantly reduced when compared with control fibroblasts. Electrophysiological measurements performed with a number of AT cell lines, as well as two matched sets of primary AT fibroblast cultures, reveal that outward rectifier K+ currents are largely absent in AT fibroblasts in comparison with control cells. These K+ current defects can be corrected in AT fibroblasts transfected with the full-length ATM cDNA. These data implicate, for the first time, a role for ATM in the regulation of K+ channel activity and membrane potential.

Authors
Rhodes, N; D'Souza, T; Foster, CD; Ziv, Y; Kirsch, DG; Shiloh, Y; Kastan, MB; Reinhart, PH; Gilmer, TM
MLA Citation
Rhodes, N, D'Souza, T, Foster, CD, Ziv, Y, Kirsch, DG, Shiloh, Y, Kastan, MB, Reinhart, PH, and Gilmer, TM. "Defective potassium currents in ataxia telangiectasia fibroblasts." Genes Dev 12.23 (December 1, 1998): 3686-3692.
PMID
9851975
Source
pubmed
Published In
Genes & development
Volume
12
Issue
23
Publish Date
1998
Start Page
3686
End Page
3692

Frequent detection of tumor cells in hematopoietic grafts in neuroblastoma and Ewing's sarcoma.

Many poor-risk neuroblastomas and tumours of the Ewing's sarcoma family (ET) recur despite autologous transplants. Recurrence may be due to tumor cells contained in the BM harvests or PBSC harvests. The objectives of this prospective study were to: (1) determine the incidence and degree of tumor cell contamination in paired BM and PBSC harvests; and (2) determine the efficacy of tumor cell purging by immunomagnetic CD34+ cell selection. 198 samples from 11 consecutive patients with neuroblastoma or Ewing's sarcoma were analyzed. We assayed tumor contamination by RT-PCR assay for PGP 9.5, plus immunohistochemistry for neuroblastoma-specific antigens (the latter in neuroblastoma only). None of these patients had tumor cells detected in their BM by clinical histology immediately before BM or PBSC harvests. However, 82% of PBSC and 89% of backup BM harvests were contaminated with tumor by RT-PCR and/or immunocytochemistry assays. Unselected PBSC and BM harvests contained similar quantities of tumor cells (median, approximately 200000 cells). Cyclophosphamide plus G-CSF mobilization did not affect the incidence or level of contamination in PBSC harvests, as compared to blood obtained before mobilization. Immunomagnetic CD34+ cell selection depleted tumor cells by a median of 3.0 logs for PBSC, and 2.6 logs for BM harvests.

Authors
Leung, W; Chen, AR; Klann, RC; Moss, TJ; Davis, JM; Noga, SJ; Cohen, KJ; Friedman, AD; Small, D; Schwartz, CL; Borowitz, MJ; Wharam, MD; Paidas, CN; Long, CA; Karandish, S; McMannis, JD; Kastan, MB; Civin, CI
MLA Citation
Leung, W, Chen, AR, Klann, RC, Moss, TJ, Davis, JM, Noga, SJ, Cohen, KJ, Friedman, AD, Small, D, Schwartz, CL, Borowitz, MJ, Wharam, MD, Paidas, CN, Long, CA, Karandish, S, McMannis, JD, Kastan, MB, and Civin, CI. "Frequent detection of tumor cells in hematopoietic grafts in neuroblastoma and Ewing's sarcoma." Bone Marrow Transplant 22.10 (November 1998): 971-979.
PMID
9849694
Source
pubmed
Published In
Bone Marrow Transplantation
Volume
22
Issue
10
Publish Date
1998
Start Page
971
End Page
979
DOI
10.1038/sj.bmt.1701471

The complexity of p53 modulation: emerging patterns from divergent signals.

Authors
Giaccia, AJ; Kastan, MB
MLA Citation
Giaccia, AJ, and Kastan, MB. "The complexity of p53 modulation: emerging patterns from divergent signals." Genes Dev 12.19 (October 1, 1998): 2973-2983. (Review)
PMID
9765199
Source
pubmed
Published In
Genes & development
Volume
12
Issue
19
Publish Date
1998
Start Page
2973
End Page
2983

Activation of the ATM kinase by ionizing radiation and phosphorylation of p53.

The p53 tumor suppressor protein is activated and phosphorylated on serine-15 in response to various DNA damaging agents. The gene product mutated in ataxia telangiectasia, ATM, acts upstream of p53 in a signal transduction pathway initiated by ionizing radiation. Immunoprecipitated ATM had intrinsic protein kinase activity and phosphorylated p53 on serine-15 in a manganese-dependent manner. Ionizing radiation, but not ultraviolet radiation, rapidly enhanced this p53-directed kinase activity of endogenous ATM. These observations, along with the fact that phosphorylation of p53 on serine-15 in response to ionizing radiation is reduced in ataxia telangiectasia cells, suggest that ATM is a protein kinase that phosphorylates p53 in vivo.

Authors
Canman, CE; Lim, DS; Cimprich, KA; Taya, Y; Tamai, K; Sakaguchi, K; Appella, E; Kastan, MB; Siliciano, JD
MLA Citation
Canman, CE, Lim, DS, Cimprich, KA, Taya, Y, Tamai, K, Sakaguchi, K, Appella, E, Kastan, MB, and Siliciano, JD. "Activation of the ATM kinase by ionizing radiation and phosphorylation of p53." Science 281.5383 (September 11, 1998): 1677-1679.
PMID
9733515
Source
pubmed
Published In
Science
Volume
281
Issue
5383
Publish Date
1998
Start Page
1677
End Page
1679

Tumor-suppressor p53: implications for tumor development and prognosis.

The p53 protein plays a central role in modulating cellular responses to cytotoxic stresses by contributing to both cell-cycle arrest and programmed cell death. Loss of p53 function during tumorigenesis can lead to inappropriate cell growth, increased cell survival, and genetic instability. p53 gene mutations occur in approximately half of all malignancies from a wide range of human tumors. In some tumor types, these p53 mutations are associated with poor prognosis and treatment failure. Based on these insights, new approaches are being developed to prevent, diagnose, and treat cancer.

Authors
Kirsch, DG; Kastan, MB
MLA Citation
Kirsch, DG, and Kastan, MB. "Tumor-suppressor p53: implications for tumor development and prognosis." J Clin Oncol 16.9 (September 1998): 3158-3168. (Review)
PMID
9738588
Source
pubmed
Published In
Journal of Clinical Oncology
Volume
16
Issue
9
Publish Date
1998
Start Page
3158
End Page
3168
DOI
10.1200/JCO.1998.16.9.3158

ATM binds to beta-adaptin in cytoplasmic vesicles.

Inherited mutations in the ATM gene lead to a complex clinical phenotype characterized by neuronal degeneration, oculocutaneous telangiectasias, immune dysfunction, and cancer predisposition. Using the yeast two-hybrid system, we demonstrate that ataxia telangiectasia mutated (ATM) binds to beta-adaptin, one of the components of the AP-2 adaptor complex, which is involved in clathrin-mediated endocytosis of receptors. The interaction between ATM and beta-adaptin was confirmed in vitro, and coimmunoprecipitation and colocalization studies show that the proteins also associate in vivo. ATM also interacts in vitro with beta-NAP, a neuronal-specific beta-adaptin homolog that was identified as an autoantigen in a patient with cerebellar degeneration. Our data describing the association of ATM with beta-adaptin in vesicles indicate that ATM may play a role in intracellular vesicle and/or protein transport mechanisms.

Authors
Lim, DS; Kirsch, DG; Canman, CE; Ahn, JH; Ziv, Y; Newman, LS; Darnell, RB; Shiloh, Y; Kastan, MB
MLA Citation
Lim, DS, Kirsch, DG, Canman, CE, Ahn, JH, Ziv, Y, Newman, LS, Darnell, RB, Shiloh, Y, and Kastan, MB. "ATM binds to beta-adaptin in cytoplasmic vesicles." Proc Natl Acad Sci U S A 95.17 (August 18, 1998): 10146-10151.
PMID
9707615
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
95
Issue
17
Publish Date
1998
Start Page
10146
End Page
10151

Human smooth muscle alpha-actin gene is a transcriptional target of the p53 tumor suppressor protein.

Smooth muscle (sm) alpha-actin is expressed in vascular smooth muscle cells and fibroblast cells. Its expression is regulated by cell proliferation and repressed during oncogenic transformation. In this study, we demonstrate that p53 activation is associated with a dramatic increase in organized microfilament bundles and an increase in sm alpha-actin mRNA level. Wild-type p53, but not mutant p53, strongly stimulated human sm alpha-actin promoter activity in p53 null cell lines. The sequences homologous to the p53 consensus sequence and to the p53 binding sequence from the muscle creatine kinase, were found within a specific region of the sm alpha-actin promoter. This sequence was sufficient to confer p53-dependent activation to a heterologous promoter and p53 was capable of binding to this sequence as assessed by gel shift analysis. Ionizing irradiation of colorectal tumor cells caused an increase in alpha-actin mRNA level in a p53-dependent manner. Taken together, these results demonstrate that human sm alpha-actin gene is a transcriptional target for p53 tumor suppressor protein and represents the first example of a cytoskeletal gene with a functionally defined p53 response element.

Authors
Comer, KA; Dennis, PA; Armstrong, L; Catino, JJ; Kastan, MB; Kumar, CC
MLA Citation
Comer, KA, Dennis, PA, Armstrong, L, Catino, JJ, Kastan, MB, and Kumar, CC. "Human smooth muscle alpha-actin gene is a transcriptional target of the p53 tumor suppressor protein." Oncogene 16.10 (March 12, 1998): 1299-1308.
PMID
9546431
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
16
Issue
10
Publish Date
1998
Start Page
1299
End Page
1308
DOI
10.1038/sj.onc.1201645

Small contribution of G1 checkpoint control manipulation to modulation of p53-mediated apoptosis.

Deregulation of the S-phase promoting E2F-1 transcription factor has been shown to cooperate with p53 to induce apoptosis. BaF3 cells undergo rapid, p53-dependent apoptosis when irradiated in the absence of IL-3. Rapid apoptosis induced by ionizing radiation (IR) coincides with attenuated p21(WAF1/Cip1) induction. Failure to adequately induce p21 could result in inappropriate release of E2F from Rb which may then cooperate with p53 to induce apoptosis in cells deprived of growth factor. We engineered BaF3 cells to express exogenous p21 and tested whether overexpressing p21 in cells irradiated in the absence of IL-3 protects from IR-induced apoptosis. Enforced p21 expression resulted in a consistent, but partial, protection of cells from undergoing IR-induced apoptosis. However, deregulating E2F activity through expression of HPV E7 failed to sensitize cells to IR-induced apoptosis in the presence of IL-3. Together, these data strongly suggest that the IL-3-responsive factors which modulate p53-mediated apoptosis in BaF3 cells are largely independent of G1 cell cycle checkpoint control mediated by p21.

Authors
Canman, CE; Kastan, MB
MLA Citation
Canman, CE, and Kastan, MB. "Small contribution of G1 checkpoint control manipulation to modulation of p53-mediated apoptosis." Oncogene 16.8 (February 26, 1998): 957-966.
PMID
9519869
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
16
Issue
8
Publish Date
1998
Start Page
957
End Page
966
DOI
10.1038/sj.onc.1201612

Modulation of cell death by Bcl-XL through caspase interaction.

The caspases are cysteine proteases that have been implicated in the execution of programmed cell death in organisms ranging from nematodes to humans. Many members of the Bcl-2 family, including Bcl-XL, are potent inhibitors of programmed cell death and inhibit activation of caspases in cells. Here, we report a direct interaction between caspases and Bcl-XL. The loop domain of Bcl-XL is cleaved by caspases in vitro and in cells induced to undergo apoptotic death after Sindbis virus infection or interleukin 3 withdrawal. Mutation of the caspase cleavage site in Bcl-XL in conjunction with a mutation in the BH1 homology domain impairs the death-inhibitory activity of Bcl-XL, suggesting that interaction of Bcl-XL with caspases may be an important mechanism of inhibiting cell death. However, once Bcl-XL is cleaved, the C-terminal fragment of Bcl-XL potently induces apoptosis. Taken together, these findings indicate that the recognition/cleavage site of Bcl-XL may facilitate protection against cell death by acting at the level of caspase activation and that cleavage of Bcl-XL during the execution phase of cell death converts Bcl-XL from a protective to a lethal protein.

Authors
Clem, RJ; Cheng, EH; Karp, CL; Kirsch, DG; Ueno, K; Takahashi, A; Kastan, MB; Griffin, DE; Earnshaw, WC; Veliuona, MA; Hardwick, JM
MLA Citation
Clem, RJ, Cheng, EH, Karp, CL, Kirsch, DG, Ueno, K, Takahashi, A, Kastan, MB, Griffin, DE, Earnshaw, WC, Veliuona, MA, and Hardwick, JM. "Modulation of cell death by Bcl-XL through caspase interaction." Proc Natl Acad Sci U S A 95.2 (January 20, 1998): 554-559.
PMID
9435230
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
95
Issue
2
Publish Date
1998
Start Page
554
End Page
559

Cellular survival pathways and resistance to cancer therapy.

Chemotherapy and irradiation induce programmed cell death (apoptosis) in their target cells. Dysregulated apoptosis is a feature that is selected for during tumor formation and contributes to therapeutic resistance. Cell survival in the face of cytotoxic therapy is dictated by both internal properties of the cell, such as status of components of the apoptotic machinery, and its extracellular milieu, such as extracellular matrix (ECM) and growth factor receptor expression and signaling. The importance of extracellular survival signals as key regulators of apoptosis is now being recognized by the ability of growth factors (GFs), GF receptors (GFRs), and GFR signaling to promote cellular survival. GFs can mitigate or abrogate the effectiveness of cancer therapy and protect against other cellular insults. Because survival signals generated by different extracellular sources converge at key molecules, new molecular targets have been identified which could be exploited to maximize the effectiveness of cytotoxic cancer therapy.

Authors
Dennis, PA; Kastan, MB
MLA Citation
Dennis, PA, and Kastan, MB. "Cellular survival pathways and resistance to cancer therapy." Drug Resist Updat 1.5 (1998): 301-309.
PMID
17092811
Source
pubmed
Published In
Drug Resistance Updates
Volume
1
Issue
5
Publish Date
1998
Start Page
301
End Page
309

DNA damage induces phosphorylation of the amino terminus of p53.

Data are presented demonstrating that DNA damage leads to specific post-translational modifications of p53 protein. Using two-dimensional peptide mapping of in vivo radiolabeled p53 tryptic phosphopeptides, recombinant truncated p53 protein, and synthetic p53 tryptic peptides, a unique p53 phosphopeptide was identified after exposure of ML-1 cells to ionizing irradiation. This peptide represents the first 24 amino acids of p53 and contains three phosphorylated serine residues. A specific p53 phosphopeptide antibody identified serine-15 as one of the two serines in p53 that becomes phosphorylated following DNA damage induced by either ionizing irradiation (IR) or ultraviolet (UV) irradiation in multiple cell types. IR-induced phosphorylation of p53 does not affect the kinetics of p53 binding to or dissociating from DNA as assessed by electrophoretic mobility-shift assays. However, p53 phosphorylation induced by DNA damage correlates with enhanced transcription of downstream p53 target genes. Low levels of phosphoserine-15 p53 are detectable within 6 hr after IR in AT cells, whereas lymphoblasts from normal individuals exhibit this modification within 1 hr. In contrast, phosphorylation of p53 on serine-15 is similar in normal and AT cells after UV irradiation. Our results indicate that p53 is phosphorylated in response to DNA damage, that this de novo phosphorylation may be involved in the subsequent induction and activation of p53, and that although ATM affects the kinetics of p53 phosphorylation after IR, it is not absolutely required for phosphorylation of p53 on serine-15.

Authors
Siliciano, JD; Canman, CE; Taya, Y; Sakaguchi, K; Appella, E; Kastan, MB
MLA Citation
Siliciano, JD, Canman, CE, Taya, Y, Sakaguchi, K, Appella, E, and Kastan, MB. "DNA damage induces phosphorylation of the amino terminus of p53." Genes Dev 11.24 (December 15, 1997): 3471-3481.
PMID
9407038
Source
pubmed
Published In
Genes & development
Volume
11
Issue
24
Publish Date
1997
Start Page
3471
End Page
3481

Conversion of Bcl-2 to a Bax-like death effector by caspases.

Caspases are a family of cysteine proteases implicated in the biochemical and morphological changes that occur during apoptosis (programmed cell death). The loop domain of Bcl-2 is cleaved at Asp34 by caspase-3 (CPP32) in vitro, in cells overexpressing caspase-3, and after induction of apoptosis by Fas ligation and interleukin-3 withdrawal. The carboxyl-terminal Bcl-2 cleavage product triggered cell death and accelerated Sindbis virus-induced apoptosis, which was dependent on the BH3 homology and transmembrane domains of Bcl-2. Inhibitor studies indicated that cleavage of Bcl-2 may further activate downstream caspases and contribute to amplification of the caspase cascade. Cleavage-resistant mutants of Bcl-2 had increased protection from interleukin-3 withdrawal and Sindbis virus-induced apoptosis. Thus, cleavage of Bcl-2 by caspases may ensure the inevitability of cell death.

Authors
Cheng, EH; Kirsch, DG; Clem, RJ; Ravi, R; Kastan, MB; Bedi, A; Ueno, K; Hardwick, JM
MLA Citation
Cheng, EH, Kirsch, DG, Clem, RJ, Ravi, R, Kastan, MB, Bedi, A, Ueno, K, and Hardwick, JM. "Conversion of Bcl-2 to a Bax-like death effector by caspases." Science 278.5345 (December 12, 1997): 1966-1968.
PMID
9395403
Source
pubmed
Published In
Science
Volume
278
Issue
5345
Publish Date
1997
Start Page
1966
End Page
1968

Influence of ATM function on telomere metabolism.

The ATM gene product, which is defective in the cancer-prone disorder ataxia telangiectasia, has been implicated in mitogenic signal transduction, chromosome condensation, meiotic recombination and cell cycle control. The ATM gene has homology with the TEL1 gene of yeast, mutations of which lead to shortened telomeres. To test the hypothesis that the ATM gene product is involved in telomere metabolism, we examined telomeric associations (TA), telomere length, and telomerase activity in human cells expressing either dominant-negative or complementing fragments of the ATM gene. The phenotype of RKO colorectal tumor cells expressing ATM fragments containing a leucine zipper (LZ) motif mimics that of ataxia telangiectasia (A-T) cells. These transfected RKO cells relative to transfected controls had a higher frequency of cells with TA and shortened telomeres, but no detectable change in telomerase activity. In addition, the percentage of cells with TA after gamma irradiation was higher in the transfected RKO cells with dominant negative activity of the ATM gene, compared to control cells. SV40 transformed fibroblasts derived from an A-T patient and transfected with a complementing carboxyl terminal kinase region of the ATM gene had a reduced frequency of cells with TA, with no effect on the telomere length or telomerase activity. The present studies using isogenic cells with manipulated ATM function demonstrate a role for the ATM gene product in telomere metabolism.

Authors
Smilenov, LB; Morgan, SE; Mellado, W; Sawant, SG; Kastan, MB; Pandita, TK
MLA Citation
Smilenov, LB, Morgan, SE, Mellado, W, Sawant, SG, Kastan, MB, and Pandita, TK. "Influence of ATM function on telomere metabolism." Oncogene 15.22 (November 27, 1997): 2659-2665.
PMID
9400992
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
15
Issue
22
Publish Date
1997
Start Page
2659
End Page
2665
DOI
10.1038/sj.onc.1201449

To oxidize or not to oxidize?

Authors
Kastan, MB
MLA Citation
Kastan, MB. "To oxidize or not to oxidize?." Nat Med 3.11 (November 1997): 1192-1193.
PMID
9359686
Source
pubmed
Published In
Nature Medicine
Volume
3
Issue
11
Publish Date
1997
Start Page
1192
End Page
1193

p53 does not repress hypoxia-induced transcription of the vascular endothelial growth factor gene.

Hypoxia-induced neovascularization mediated by vascular endothelial growth factor (VEGF) contributes to tumor progression. Based on its effects when overexpressed in transient transfection assays, p53 has been proposed to repress VEGF transcription. To investigate this hypothesis, we have analyzed endogenous VEGF mRNA levels in Hep3B cells stably expressing an inducible p53-estrogen receptor fusion protein and in irradiated RKO cells expressing endogenous wild-type p53. In both cell lines, VEGF mRNA levels increased in response to hypoxia, either in the presence or absence of functional p53. Our data provide no evidence for a causal relationship between the loss of p53 activity and increased VEGF expression that is observed during tumor progression. Studies that attribute repressor functions to p53 based on analysis of cells transiently overexpressing this protein should be interpreted cautiously.

Authors
Agani, F; Kirsch, DG; Friedman, SL; Kastan, MB; Semenza, GL
MLA Citation
Agani, F, Kirsch, DG, Friedman, SL, Kastan, MB, and Semenza, GL. "p53 does not repress hypoxia-induced transcription of the vascular endothelial growth factor gene." Cancer Res 57.20 (October 15, 1997): 4474-4477.
PMID
9377555
Source
pubmed
Published In
Cancer Research
Volume
57
Issue
20
Publish Date
1997
Start Page
4474
End Page
4477

Rapamycin and p53 act on different pathways to induce G1 arrest in mammalian cells.

Certain growth regulatory kinases contain a common domain related to the phospho-inositol 3 (PI-3) kinase catalytic site. These include the ATM gene product, DNA-PKcs, and the target of rapamycin (TOR in yeast; and FRAP in mammalian cells). Rapamycin inhibits growth factor signalling and induces G1 arrest in many cell types. Some growth regulatory PI-3 kinases appear functionally linked to p53 and we have explored potential links between cellular effects induced by rapamycin and p53. In p53 null cells rapamycin inhibited cell cycling but did not induce G1 arrest. In cells which showed selective G1 arrest in response to rapamycin, rapamycin had no effect on basal levels of p53 protein. Similarly p21(WAF1) protein was not induced by rapamycin. The kinetics of the cellular p53/p21(WAF1) response to ionising radiation was unaffected by rapamycin; and the ability of growth factor to protect against p53-mediated apoptosis in response to DNA damage was also unaffected by rapamycin. The ATM gene is mutated in the cancer susceptibility syndrome ataxia telangiectasia (AT) but such mutant cells showed a similar sensitivity to rapamycin compared to their normal counterparts. RKO cell lines of common genetic background, but with different levels of functional p53 protein, also responded similarly to rapamycin. Thus, although rapamycin and p53 are each able to induce G1 arrest, they appear to act through independent growth regulatory pathways.

Authors
Metcalfe, SM; Canman, CE; Milner, J; Morris, RE; Goldman, S; Kastan, MB
MLA Citation
Metcalfe, SM, Canman, CE, Milner, J, Morris, RE, Goldman, S, and Kastan, MB. "Rapamycin and p53 act on different pathways to induce G1 arrest in mammalian cells." Oncogene 15.14 (October 2, 1997): 1635-1642.
PMID
9349496
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
15
Issue
14
Publish Date
1997
Start Page
1635
End Page
1642
DOI
10.1038/sj.onc.1201341

Untitled

Authors
Chabner, BA; Kastan, MB; Teicher, BA
MLA Citation
Chabner, BA, Kastan, MB, and Teicher, BA. "Untitled." CLINICAL CANCER RESEARCH 3.9 (September 1997): 1455-1455.
Source
wos-lite
Published In
Clinical cancer research : an official journal of the American Association for Cancer Research
Volume
3
Issue
9
Publish Date
1997
Start Page
1455
End Page
1455

Dissociation of radiation-induced phosphorylation of replication protein A from the S-phase checkpoint.

Replication protein A (RPA) is a trimeric single-stranded DNA-binding protein complex involved in DNA replication, repair, and recombination. DNA damage induces phosphorylation of the RPA p34 subunit, and it has been speculated that this phosphorylation could contribute to the regulation of the DNA damage-induced S-phase checkpoint. To further examine this potential relationship, human cell lines expressing ataxia telangiectasia (AT)-mutated dominant-negative fragments, which fail to arrest in S phase in response to ionizing radiation (IR), and AT cells expressing AT-mutated-complementing fragments, which regain the ability to arrest replicative DNA synthesis in response to IR, were analyzed for radiation-induced RPA phosphorylation. Results from these studies demonstrate that IR-induced RPA phosphorylation can be uncoupled from the S-phase checkpoint, suggesting that RPA phosphorylation in response to IR is neither necessary nor sufficient for an S-phase arrest.

Authors
Morgan, SE; Kastan, MB
MLA Citation
Morgan, SE, and Kastan, MB. "Dissociation of radiation-induced phosphorylation of replication protein A from the S-phase checkpoint." Cancer Res 57.16 (August 15, 1997): 3386-3389.
PMID
9270001
Source
pubmed
Published In
Cancer Research
Volume
57
Issue
16
Publish Date
1997
Start Page
3386
End Page
3389

Cell cycle and cell death after DNA damage

Authors
Kastan, MB; Morgan, SE; Siliciano, J; Kirsch, D; Dennis, P; Canman, CE
MLA Citation
Kastan, MB, Morgan, SE, Siliciano, J, Kirsch, D, Dennis, P, and Canman, CE. "Cell cycle and cell death after DNA damage." FASEB JOURNAL 11.9 (July 31, 1997): A879-A879.
Source
wos-lite
Published In
The FASEB journal : official publication of the Federation of American Societies for Experimental Biology
Volume
11
Issue
9
Publish Date
1997
Start Page
A879
End Page
A879

Ataxia telangiectasia mutant protein activates c-Abl tyrosine kinase in response to ionizing radiation.

Ataxia telangiectasia (AT) is a rare human autosomal recessive disorder with pleiotropic phenotypes, including neuronal degeneration, immune dysfunction, premature ageing and increased cancer risk. The gene mutated in AT, ATM, encodes a putative lipid or protein kinase. Most of the human AT patient phenotypes are recapitulated in Atm-deficient mice. Cells derived from Atm-/- mice, like those from AT patients, exhibit abnormal response to ionizing radiation. One of the known responses to ionizing radiation is the activation of a nuclear tyrosine kinase encoded by the c-abl proto-oncogene. Ionizing radiation does not activate c-Abl in cells from AT patients or in thymocytes or fibroblasts from the Atm-deficient mice. Ectopic expression of a functional ATM kinase domain corrects this defect, as it phosphorylates the c-Abl tyrosine kinase in vitro at Ser 465, leading to the activation of c-Abl. A mutant c-Abl with Ser 465 changed to Ala 465 is not activated by ionizing radiation or ATM kinase in vivo. These findings identify the c-Abl tyrosine kinase as a downstream target of phosphorylation and activation by the ATM kinase in the cellular response to ionizing radiation.

Authors
Baskaran, R; Wood, LD; Whitaker, LL; Canman, CE; Morgan, SE; Xu, Y; Barlow, C; Baltimore, D; Wynshaw-Boris, A; Kastan, MB; Wang, JY
MLA Citation
Baskaran, R, Wood, LD, Whitaker, LL, Canman, CE, Morgan, SE, Xu, Y, Barlow, C, Baltimore, D, Wynshaw-Boris, A, Kastan, MB, and Wang, JY. "Ataxia telangiectasia mutant protein activates c-Abl tyrosine kinase in response to ionizing radiation." Nature 387.6632 (May 29, 1997): 516-519.
PMID
9168116
Source
pubmed
Published In
Nature
Volume
387
Issue
6632
Publish Date
1997
Start Page
516
End Page
519
DOI
10.1038/387516a0

Apoptosis in haematological malignancies.

Authors
DiGiuseppe, JA; Kastan, MB
MLA Citation
DiGiuseppe, JA, and Kastan, MB. "Apoptosis in haematological malignancies." J Clin Pathol 50.5 (May 1997): 361-364.
PMID
9215115
Source
pubmed
Published In
Journal of Clinical Pathology
Volume
50
Issue
5
Publish Date
1997
Start Page
361
End Page
364

Fragments of ATM which have dominant-negative or complementing activity.

The ATM protein has been implicated in pathways controlling cell cycle checkpoints, radiosensitivity, genetic instability, and aging. Expression of ATM fragments containing a leucine zipper motif in a human tumor cell line abrogated the S-phase checkpoint after ionizing irradiation and enhanced radiosensitivity and chromosomal breakage. These fragments did not abrogate irradiation-induced G1 or G2 checkpoints, suggesting that cell cycle checkpoint defects alone cannot account for chromosomal instability in ataxia telangiectasia (AT) cells. Expression of the carboxy-terminal portion of ATM, which contains the PI-3 kinase domain, complemented radiosensitivity and the S-phase checkpoint and reduced chromosomal breakage after irradiation in AT cells. These observations suggest that ATM function is dependent on interactions with itself or other proteins through the leucine zipper region and that the PI-3 kinase domain contains much of the significant activity of ATM.

Authors
Morgan, SE; Lovly, C; Pandita, TK; Shiloh, Y; Kastan, MB
MLA Citation
Morgan, SE, Lovly, C, Pandita, TK, Shiloh, Y, and Kastan, MB. "Fragments of ATM which have dominant-negative or complementing activity." Mol Cell Biol 17.4 (April 1997): 2020-2029.
PMID
9121450
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
17
Issue
4
Publish Date
1997
Start Page
2020
End Page
2029

On the TRAIL from p53 to apoptosis?

Authors
Kastan, M
MLA Citation
Kastan, M. "On the TRAIL from p53 to apoptosis?." Nature genetics 17.2 (1997): 130-131.
PMID
9326922
Source
scival
Published In
Nature Genetics
Volume
17
Issue
2
Publish Date
1997
Start Page
130
End Page
131

Cell cycle and cell death after DNA damaye

A variety of cellular responses to DNA damage influence cellular fate, such as whether heritable genetic alterations are passed on to daughter cells and whether the cell survives the damaging insult. The p53 and ATM gene products play critical roles in modulating perturbations in cell cycle progression and in programmed cell death after DNA damage. Posttranscriptional increases in p53 protein levels after introduction of DNA strand breaks can lead to either arrest of the cell cycle in G l or in apoptotic death of the cell. Loss of p53 function may be selected for during tumorigenesis to reduce programmed cell death, but p53 mutations may then contribute further to tumor progression by the additional mechanism of enhanced genetic instability. Growth factor signalling pathways can inhibit the DNA damage-induced apoptotic death and may provide a novel target for enhancing tumor kill after chemo/radiation therapy. DNA damage induces a specific phosphorylation change in p53 protein which may contribute to its induction. The ATM protein is homologous to the yeast DNA damage response proteins rad3, tell, and mecl and is required for normal induction of p53 after ionizing irradiation. ATM dysfunction leads to radiosensitivity, enhanced chromosomal breakage, and loss of cell cycle checkpoints. Identification of dominant-negative and complementing fragments of ATM has facilitated investigations into the mechanisms of ATM function.

Authors
Kastan, MB; Morgan, SE; Siliciano, J; Kirsch, D; Dennis, P; Canman, CE
MLA Citation
Kastan, MB, Morgan, SE, Siliciano, J, Kirsch, D, Dennis, P, and Canman, CE. "Cell cycle and cell death after DNA damaye." FASEB Journal 11.9 (1997): A878-.
Source
scival
Published In
The FASEB journal : official publication of the Federation of American Societies for Experimental Biology
Volume
11
Issue
9
Publish Date
1997
Start Page
A878

Genetic instability and tumorigenesis: introduction.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Genetic instability and tumorigenesis: introduction." Curr Top Microbiol Immunol 221 (1997): 1-4.
PMID
8979436
Source
pubmed
Published In
Current topics in microbiology and immunology
Volume
221
Publish Date
1997
Start Page
1
End Page
4

p53 and ATM: cell cycle, cell death, and cancer.

The development of a normal cell into a tumor cell appears to depend in part on mutations in genes that normally control cell cycle and cell death, thereby resulting in inappropriate cellular survival and tumorigenesis. ATM ("mutated in ataxia-telangiectasia") and p53 are two gene products that are believed to play a major role in maintaining the integrity of the genome such that alterations in these gene products may contribute to increased incidence of genomic changes such as deletions, translocations, and amplifications, which are common during oncogenesis. p53 is a critical participant in a signal transduction pathway that mediates either a G1 arrest or apoptosis in response to DNA damage. In addition, p53 is believed to be involved in the mitotic spindle checkpoint and in the regulation of centrosome function. Following certain cytotoxic stresses, normal ATM function is required for p53-mediated G1 arrest. ATM is also involved in other cellular processes such as S phase and G2-M phase arrest and in radiosensitivity. The understanding of the roles that both p53 and ATM play in cell cycle progression and cell death in response to DNA damage may provide new insights into the molecular mechanisms of cellular transformation and may help identify potential targets for improved cancer therapies.

Authors
Morgan, SE; Kastan, MB
MLA Citation
Morgan, SE, and Kastan, MB. "p53 and ATM: cell cycle, cell death, and cancer." Adv Cancer Res 71 (1997): 1-25. (Review)
PMID
9111862
Source
pubmed
Published In
Advances in cancer research
Volume
71
Publish Date
1997
Start Page
1
End Page
25

Checkpoint controls and cancer. Introduction.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Checkpoint controls and cancer. Introduction." Cancer Surv 29 (1997): 1-6.
PMID
9338093
Source
pubmed
Published In
Cancer surveys
Volume
29
Publish Date
1997
Start Page
1
End Page
6

Role of p53 in apoptosis.

Authors
Canman, CE; Kastan, MB
MLA Citation
Canman, CE, and Kastan, MB. "Role of p53 in apoptosis." Adv Pharmacol 41 (1997): 429-460. (Review)
PMID
9204155
Source
pubmed
Published In
Advances in pharmacology (San Diego, Calif.)
Volume
41
Publish Date
1997
Start Page
429
End Page
460

Signal transduction. Three paths to stress relief.

Authors
Canman, CE; Kastan, MB
MLA Citation
Canman, CE, and Kastan, MB. "Signal transduction. Three paths to stress relief." Nature 384.6606 (November 21, 1996): 213-214.
PMID
8918868
Source
pubmed
Published In
Nature
Volume
384
Issue
6606
Publish Date
1996
Start Page
213
End Page
214
DOI
10.1038/384213a0

Growth factor modulation of p21(WAF1/CIP1) in primary acute myeloid leukemias.

Authors
DiGiuseppe, JA; Gore, SD; Weng, LJ; Kastan, MB
MLA Citation
DiGiuseppe, JA, Gore, SD, Weng, LJ, and Kastan, MB. "Growth factor modulation of p21(WAF1/CIP1) in primary acute myeloid leukemias." BLOOD 88.10 (November 15, 1996): 331-331.
Source
wos-lite
Published In
Blood
Volume
88
Issue
10
Publish Date
1996
Start Page
331
End Page
331

Chromosome end-to-end associations and telomerase activity during cancer progression in human cells after treatment with alpha-particles simulating radon progeny.

Chromosome end-to-end associations seen at metaphase involve telomeres and are commonly observed in cells derived from individuals with ataxia telangiectasia and most types of human tumors. The associations may arise because of short telomeres and/or alterations of chromatin structure. There is a growing consensus that telomere length is stabilized by the activity of telomerase in immortal cells; however, it is not clear why some immortal cells display chromosome end-to-end associations. In the present study we evaluated chromosome end-to-end associations, telomere length and telomerase activity with the tumorigenic status of human bronchial epithelial cells immortalized with human papillomavirus. Oncogenic transformation was initiated using radon simulated alpha-particles and cells evaluated as primary, secondary and metastatic transformants. The fewest chromosome end associations and lowest telomerase activity were observed in the parental immortalized cells. However, increased levels of telomerase activity were detected in alpha-particle survivors while robust telomerase activity was seen in the tumorigenic cell lines. The tumorigenic cells that were telomerase positive and had the highest frequency of cells with chromosome end-to-end associations were also metastatic. No correlation was found between telomere length and the different stages of carcinogenicity.

Authors
Pandita, TK; Hall, EJ; Hei, TK; Piatyszek, MA; Wright, WE; Piao, CQ; Pandita, RK; Willey, JC; Geard, CR; Kastan, MB; Shay, JW
MLA Citation
Pandita, TK, Hall, EJ, Hei, TK, Piatyszek, MA, Wright, WE, Piao, CQ, Pandita, RK, Willey, JC, Geard, CR, Kastan, MB, and Shay, JW. "Chromosome end-to-end associations and telomerase activity during cancer progression in human cells after treatment with alpha-particles simulating radon progeny." Oncogene 13.7 (October 3, 1996): 1423-1430.
PMID
8875980
Source
pubmed
Published In
Oncogene: Including Oncogene Reviews
Volume
13
Issue
7
Publish Date
1996
Start Page
1423
End Page
1430

Separate pathways for p53 induction by ionizing radiation and N-(phosphonoacetyl)-L-aspartate.

The tumor suppressor gene product, p53, appears to be a significant participant in signaling pathways that mediate cellular responses to cytotoxic stresses. In particular, p53 appears to be a critical determinant of whether the cell lives or dies and how it progresses through the cell cycle after the cytotoxic exposure. Many of the molecular details for these signaling pathways remain to be elucidated, and whether all cytotoxic signals utilize the same pathway to increase p53 expression is not clear. Here, we demonstrate the existence of cell types in which the induction of p53 and associated G1 arrest by the antimetabolite, N-(phosphonoacetyl)-L-aspartate (PALA), is defective, whereas p53 induction and G1 arrest induced by ionizing radiation are intact. These observations demonstrate the existence of genetic defects that can alter p53 induction and associated cellular outcomes after some, but not all, cytotoxic insults and suggest distinct pathways of p53 induction by PALA and ionizing radiation.

Authors
Chen, CY; Hall, I; Lansing, TJ; Gilmer, TM; Tlsty, TD; Kastan, MB
MLA Citation
Chen, CY, Hall, I, Lansing, TJ, Gilmer, TM, Tlsty, TD, and Kastan, MB. "Separate pathways for p53 induction by ionizing radiation and N-(phosphonoacetyl)-L-aspartate." Cancer Res 56.16 (August 15, 1996): 3659-3662.
PMID
8706003
Source
pubmed
Published In
Cancer Research
Volume
56
Issue
16
Publish Date
1996
Start Page
3659
End Page
3662

Reversal of apoptosis by the leukaemia-associated E2A-HLF chimaeric transcription factor.

The E2A-HLF (for hepatic leukaemia factor) fusion gene, formed by action of the t(17;19) (q22;p13) chromosomal translocation, drives the leukaemic transformation of early B-cell precursors, but the mechanism of this activity remains unknown. Here we report that human leukaemia cells carrying the translocation t(17;19) rapidly died by apoptosis when programmed to express a dominant-negative suppressor of the fusion protein E2A-HLF, indicating that the chimaeric oncoprotein probably affects cell survival rather than cell growth. Moreover, when introduced into murine pro-B lymphocytes, the oncogenic E2A-HLF fusion protein reversed both interleukin-3-dependent and p53-mediated apoptosis. The close homology of the basic region/leucine zipper (bZIP) DNA-binding and dimerization domain of HLF to that of the CES-2 cell-death specification protein of Caenorhabditis elegans suggests a model of leukaemogenesis in which E2A-HLF blocks an early step within an evolutionarily conserved cell-death pathway.

Authors
Inaba, T; Inukai, T; Yoshihara, T; Seyschab, H; Ashmun, RA; Canman, CE; Laken, SJ; Kastan, MB; Look, AT
MLA Citation
Inaba, T, Inukai, T, Yoshihara, T, Seyschab, H, Ashmun, RA, Canman, CE, Laken, SJ, Kastan, MB, and Look, AT. "Reversal of apoptosis by the leukaemia-associated E2A-HLF chimaeric transcription factor." Nature 382.6591 (August 8, 1996): 541-544.
PMID
8700228
Source
pubmed
Published In
Nature
Volume
382
Issue
6591
Publish Date
1996
Start Page
541
End Page
544
DOI
10.1038/382541a0

Signalling to p53: where does it all start?

Alterations in the p53 gene product appear to be a major factor in human tumorigenesis and may influence the responses of many human tumors to therapy. Much effort has focused on understanding the signals which normally initiate p53 growth-suppressive functions. Though it has been known that DNA damage can induce p53, a recent publication reports data which suggest that p53 can be induced by depletion of ribonucleotide pools, even in the absence of detectable DNA damage(1). These observations provide new ideas about how cells utilize the p53 signal and open up new avenues of investigation for manipulating p53 function.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Signalling to p53: where does it all start?." Bioessays 18.8 (August 1996): 617-619. (Review)
PMID
8760334
Source
pubmed
Published In
Bioessays
Volume
18
Issue
8
Publish Date
1996
Start Page
617
End Page
619
DOI
10.1002/bies.950180804

The p53 signal transduction pathway is intact in human neuroblastoma despite cytoplasmic localization.

Mutations of the p53 tumor suppressor gene are rarely found in neuroblastoma. Though typically a nuclear protein, a number of tumor cell types have recently been reported to exhibit cytoplasmic p53 immunostaining, and it has been suggested that altered cellular localization is another mechanism of inhibiting p53 function. We examined p53 protein expression, localization, and function in neuroblastoma cell lines with wild-type p53 genes. Basal p53 levels were largely confined to the cytoplasmic compartment in these cells. However, after irradiation, p53 protein levels increased predominately in the nucleus. Transcriptional activity of p53 was intact in these cells because "downstream" proteins, p21WAF1 and MDM2, were induced by irradiation. In contrast to a neuroblastoma cell line harboring a mutant p53 gene, the neuroblastoma cells with wild-type protein were associated with an intact G1 arrest after DNA damage. The induced nuclear protein in these neuroblastoma cells also appeared functional as measured by its capacity to bind to a DNA oligomer containing a p53-consensus sequence. We have concluded that although p53 expression in neuroblastoma cells is primarily localized to the cytosol, ionizing radiation induces a functional p53 protein in the nucleus and that this cytoplasmic sequestration of p53 in human neuroblastoma is not a mechanism of inactivating p53 function.

Authors
Goldman, SC; Chen, CY; Lansing, TJ; Gilmer, TM; Kastan, MB
MLA Citation
Goldman, SC, Chen, CY, Lansing, TJ, Gilmer, TM, and Kastan, MB. "The p53 signal transduction pathway is intact in human neuroblastoma despite cytoplasmic localization." Am J Pathol 148.5 (May 1996): 1381-1385.
PMID
8623910
Source
pubmed
Published In
The American journal of pathology
Volume
148
Issue
5
Publish Date
1996
Start Page
1381
End Page
1385

Human CD34+ hematopoietic progenitors have low, cytokine-unresponsive O6-alkylguanine-DNA alkyltransferase and are sensitive to O6-benzylguanine plus BCNU

Human bone marrow (BM) cells contain low levels of the DNA repair protein, O6-alkylguanine-DNA alkyltransferase, which may explain their susceptibility to nitrosourea-induced cytotoxicity and the development of secondary leukemia after nitrosourea treatment. Isolated CD34+ myeloid progenitors were also found to have low levels of alkyltransferase activity. The level of alkyltransferase in CD34+ cells or in mononuclear BM cells did not increase after incubation with granulocyte-macrophage colony-stimulating factor, interleukin-3, stem cell factor, the combination, or 5637 conditioned medium. BCNU sensitivity remained unchanged as well. In addition, O6- benzylguanine depleted alkyltransferase activity in BM cells at concentrations as low as 1.5 μmol/L after a 1-hour exposure. O6- benzylguanine pretreatment markedly sensitized hematopoietic progenitor colony-forming cells to BCNU, resulting in a reduction in the dose of drug (termed the dose-modification factor) required to inhibit 50% of the colony formation (IC50) of threefold to fivefold. Since, unlike many other cell types, proliferating early (CD34+) hematopoietic precursors do not induce alkyltransferase, myelosuppression may be the dose-limiting toxicity of the combination of O6-benzylguanine plus BCNU in clinical trials.

Authors
Gerson, SL; Phillips, W; Kastan, M; Dumenco, LL; Donovan, C
MLA Citation
Gerson, SL, Phillips, W, Kastan, M, Dumenco, LL, and Donovan, C. "Human CD34+ hematopoietic progenitors have low, cytokine-unresponsive O6-alkylguanine-DNA alkyltransferase and are sensitive to O6-benzylguanine plus BCNU." Blood 88.5 (1996): 1649-1655.
PMID
8781420
Source
scival
Published In
Blood
Volume
88
Issue
5
Publish Date
1996
Start Page
1649
End Page
1655

Molecular biology of normal development, malignancy and its suppression

Authors
Liebermann, DA; Myers, A; Weinhouse, S; Nowell, PC; Jr, AJF; Kastan, MB; White, E; Tisty, TD; Ihle, JN; Waxman, S; Reddy, P
MLA Citation
Liebermann, DA, Myers, A, Weinhouse, S, Nowell, PC, Jr, AJF, Kastan, MB, White, E, Tisty, TD, Ihle, JN, Waxman, S, and Reddy, P. "Molecular biology of normal development, malignancy and its suppression." Oncogene 12.10 (1996): 2247-2250.
PMID
8668352
Source
scival
Published In
Oncogene: Including Oncogene Reviews
Volume
12
Issue
10
Publish Date
1996
Start Page
2247
End Page
2250

The oncogenic E2A-HLF fusion protein protects leukemic B-precursor cells from apoptosis.

Authors
Inaba, T; Inukai, T; Yoshihara, T; Seyschab, H; Ashmun, RA; Canman, CE; Laken, SJ; Kastan, MB; Look, AT
MLA Citation
Inaba, T, Inukai, T, Yoshihara, T, Seyschab, H, Ashmun, RA, Canman, CE, Laken, SJ, Kastan, MB, and Look, AT. "The oncogenic E2A-HLF fusion protein protects leukemic B-precursor cells from apoptosis." BLOOD 86.10 (November 15, 1995): 1297-1297.
Source
wos-lite
Published In
Blood
Volume
86
Issue
10
Publish Date
1995
Start Page
1297
End Page
1297

DNA damage induced apoptosis by p53-mediated activation of p34(cdc2) kinase.

Authors
Yao, S; Akhtar, AJ; Bedi, GC; Sidransky, D; Kastan, MB; Barber, JP; McKenna, KA; Collector, MI; Sharkis, SJ; Jones, RJ; Bedi, A
MLA Citation
Yao, S, Akhtar, AJ, Bedi, GC, Sidransky, D, Kastan, MB, Barber, JP, McKenna, KA, Collector, MI, Sharkis, SJ, Jones, RJ, and Bedi, A. "DNA damage induced apoptosis by p53-mediated activation of p34(cdc2) kinase." BLOOD 86.10 (November 15, 1995): 1714-1714.
Source
wos-lite
Published In
Blood
Volume
86
Issue
10
Publish Date
1995
Start Page
1714
End Page
1714

The production and characterization of murine monoclonal antibodies to human Gadd45 raised against a recombinant protein.

The production of two different murine monoclonal antibodies to human Gadd45, a protein that is induced in response to DNA damage, is reported. Antibodies were generated in a SJL mouse using a recombinant form of the human Gadd45 protein. Monoclonal antibody 4TCYA1, which recognizes the denatured form of human Gadd45 in Western blots, was selected based upon the recognition of Gadd45 induced by functional p53 in the human myeloid leukemia cell line, ML-1. A second monoclonal antibody, designated 30T.14, immunoprecipitates native human Gadd45 in lysates produced from RKO cells, a colorectal carcinoma cell line that expresses relatively high basal levels of Gadd45, as well as from cell lysates made from ML-1 cells after exposure to ionizing irradiation (IR). Since 4TCYA1 fails to immunoprecipitate Gadd45, and 30T.14 fails to bind to IR-induced Gadd45 in immunoblotting, these two monoclonal antibodies probably recognize different epitopes.

Authors
Kilpatrick, KE; Carrier, F; Smith, ML; Chen, CY; Lee, AJ; Rusnak, DW; Kastan, MB; Fornace, AJ; Champion, BR; Gilmer, TM
MLA Citation
Kilpatrick, KE, Carrier, F, Smith, ML, Chen, CY, Lee, AJ, Rusnak, DW, Kastan, MB, Fornace, AJ, Champion, BR, and Gilmer, TM. "The production and characterization of murine monoclonal antibodies to human Gadd45 raised against a recombinant protein." Hybridoma 14.4 (August 1995): 355-359.
PMID
8522347
Source
pubmed
Published In
Hybridoma
Volume
14
Issue
4
Publish Date
1995
Start Page
355
End Page
359
DOI
10.1089/hyb.1995.14.355

Growth factor modulation of p53-mediated growth arrest versus apoptosis.

Irradiation of mammalian cells can cause cell cycle perturbations and apoptotic cell death. We have investigated the modulation of these physiologic end points by growth factor stimulation: irradiation of a murine hematopoietic cell line in the presence of interlekin-3 (IL-3) induces G1 arrest, and irradiation in the absence of IL-3 results in rapid apoptotic cell death. Both of these end points are dependent on p53. Transient removal of IL-3 at the time of irradiation results in decreased clonogenic survival of irradiated cells. The removal of IL-3 results in a failure of the irradiated cells to arrest at the G1 checkpoint, despite induction of p53 and p21WAF1/CIP1, and then the cells enter S-phase where they undergo apoptosis. There are no cytokine-related changes in Bcl-2, Bax, or Bcl-x protein levels that could account for the modulation of G1 arrest versus apoptosis by growth factors. In contrast, rapid p53-independent alterations of basal levels of gadd45 and p21WAF1/CIP1 expression are linked to IL-3 withdrawal, suggesting a potential mechanism for this modulation. Constitutive activation of cytokine-like pathways with induced expression of v-Src or activated c-Raf inhibits the radiation-induced apoptosis and the alterations in p21WAF1/CIP1 and gadd45 expression. These observations suggest additional molecular mechanisms that can contribute to the development of radioresistance and resistance to apoptosis during tumorigenesis and provide an explanation for the observed lack of p53 mutations in some tumor types. In addition, these data suggest that oncogenic changes occurring during multistep tumorigenesis could be classified as those that either enhance or decrease apoptosis tendencies.

Authors
Canman, CE; Gilmer, TM; Coutts, SB; Kastan, MB
MLA Citation
Canman, CE, Gilmer, TM, Coutts, SB, and Kastan, MB. "Growth factor modulation of p53-mediated growth arrest versus apoptosis." Genes Dev 9.5 (March 1, 1995): 600-611.
PMID
7698649
Source
pubmed
Published In
Genes & development
Volume
9
Issue
5
Publish Date
1995
Start Page
600
End Page
611

P53, cell cycle control and apoptosis: implications for cancer.

Cellular proliferation depends on the rates of both cell division and cell death. Tumors frequently have decreased cell death as a primary mode of increased cell proliferation. Genetic changes resulting in loss of programmed cell death (apoptosis) are likely to be critical components of tumorigenesis. Many of the gene products which appear to control apoptotic tendencies are regulators of cell cycle progression; thus, cell cycle control and cell death appear to be tightly linked processes. P53 protein is an example of a gene product which affects both cell cycle progression and apoptosis. The ability of p53 overexpression to induce apoptosis may be a major reason why tumor cells frequently disable p53 during the transformation process. Unfortunately, the same genetic changes which cause loss of apoptosis during tumor development, may also result in tumor cell resistance to anti-neoplastic therapies which kill tumor cells by apoptosis. Elucidation of the genetic and biochemical controls of these cellular responses may provide insights into ways to induce cell death and thus hopefully suggest new targets for improving therapeutic index in the treatment of malignancies.

Authors
Kastan, MB; Canman, CE; Leonard, CJ
MLA Citation
Kastan, MB, Canman, CE, and Leonard, CJ. "P53, cell cycle control and apoptosis: implications for cancer." Cancer Metastasis Rev 14.1 (March 1995): 3-15. (Review)
PMID
7606818
Source
pubmed
Published In
Cancer and Metastasis Reviews
Volume
14
Issue
1
Publish Date
1995
Start Page
3
End Page
15

Induction of apoptosis by tumor suppressor genes and oncogenes.

The p53 tumor suppressor gene product, and the bcr-abl, bcl-2, and c-myc gene products all appear to influence the susceptibility of cells to apoptosis. In addition to the role p53 protein plays in mediating a cell cycle arrest in G1 following DNA damage, p53 also performs functions critical for removal of damaged cells by initiating apoptosis in certain physiological situations. Cells which express deregulated c-myc are sensitized to apoptosis following various growth suppressing stimuli and these observations have provided new insights into how apoptosis-suppressing genes such as mutant p53, bcl-2 and bcr-abl may cooperate during transformation and how they might influence the sensitivity of cells to radiation and chemotherapy.

Authors
Canman, CE; Kastan, MB
MLA Citation
Canman, CE, and Kastan, MB. "Induction of apoptosis by tumor suppressor genes and oncogenes." Semin Cancer Biol 6.1 (February 1995): 17-25. (Review)
PMID
7548837
Source
pubmed
Published In
Seminars in Cancer Biology
Volume
6
Issue
1
Publish Date
1995
Start Page
17
End Page
25
DOI
10.1006/scbi.1995.0003

The role of p53 in cell-cycle control and apoptosis: implications for cancer.

Authors
Leonard, CJ; Canman, CE; Kastan, MB
MLA Citation
Leonard, CJ, Canman, CE, and Kastan, MB. "The role of p53 in cell-cycle control and apoptosis: implications for cancer." Important Adv Oncol (1995): 33-42. (Review)
PMID
7672812
Source
pubmed
Published In
Important advances in oncology
Publish Date
1995
Start Page
33
End Page
42

Ataxia-telangiectasia - Broad implications for a rare disorder

Authors
Kastan, M
MLA Citation
Kastan, M. "Ataxia-telangiectasia - Broad implications for a rare disorder." New England Journal of Medicine 333.10 (1995): 662-663.
PMID
7637733
Source
scival
Published In
New England Journal of Medicine
Volume
333
Issue
10
Publish Date
1995
Start Page
662
End Page
663
DOI
10.1056/NEJM199509073331014

Similarity of the DNA-damage responsiveness and growth-suppressive properties of WAF1/CIP1 and GADD45

The cellular responses to genotoxic stress are complex involving both p53-dependent and independent mechanisms. In the case of the GADD genes, many stresses eliciting growth arrest have been shown to induce these genes in a coordinate fashion regardless of p53 status, while the ionizing radiation response (IR) of GADD45 has been found to be strictly p53-dependent. In the current study, the response of GADD45 was compared to the p53-regulated genes WAF1/CIP1 and MDM2 in a panel of human lines with known p53 status and also in mouse embryo fibroblasts where one or both alleles of p53 had been deleted. After IR, all 3 genes showed very similar transcriptional responses as measured by rapid increases in mRNA in a p53-dependent manner. Like GADD45, the WAF1/CIP1 induction by IR can be enhanced by the radiosensitizer iododeoxyuridine, and provides further evidence that DNA strand breaks can act as a signal for activation of the p53 pathway. In addition, caffeine, which blocks IR cell-cycle checkpoint activation, reduced IR induction for both genes. Unlike the case for IR, only WAF1/CIP1 showed a consistent similarity to GADD45 to DNA base-damaging agents, where appreciable induction occurred in cells regardless of p53 status. The similarity between WAF1/CIP1 and GADD45 also extended to their growth suppressive properties, and a combination of expression vectors for these genes suppressed growth appreciably more than either alone. A reasonable interpretation of these results is that growth suppression after DNA damage by either p53-dependent or independent pathways is mediated by the combined action of multiple downstream effecters including WAF1/CIP1 and GADD45.

Authors
Zhan, Q; El-Deiry, W; Bae, I; Alamo, I; Kastan, MB; Vogelstein, B; Jr, AF
MLA Citation
Zhan, Q, El-Deiry, W, Bae, I, Alamo, I, Kastan, MB, Vogelstein, B, and Jr, AF. "Similarity of the DNA-damage responsiveness and growth-suppressive properties of WAF1/CIP1 and GADD45." International Journal of Oncology 6.5 (1995): 937-946.
PMID
21556622
Source
scival
Published In
International Journal of Oncology
Volume
6
Issue
5
Publish Date
1995
Start Page
937
End Page
946

Cell cycle control and cancer.

Multiple genetic changes occur during the evolution of normal cells into cancer cells. This evolution is facilitated in cancer cells by loss of fidelity in the processes that replicate, repair, and segregate the genome. Recent advances in our understanding of the cell cycle reveal how fidelity is normally achieved by the coordinated activity of cyclin-dependent kinases, checkpoint controls, and repair pathways and how this fidelity can be abrogated by specific genetic changes. These insights suggest molecular mechanisms for cellular transformation and may help to identify potential targets for improved cancer therapies.

Authors
Hartwell, LH; Kastan, MB
MLA Citation
Hartwell, LH, and Kastan, MB. "Cell cycle control and cancer." Science 266.5192 (December 16, 1994): 1821-1828. (Review)
PMID
7997877
Source
pubmed
Published In
Science
Volume
266
Issue
5192
Publish Date
1994
Start Page
1821
End Page
1828

Interaction of the p53-regulated protein Gadd45 with proliferating cell nuclear antigen.

GADD45 is a ubiquitously expressed mammalian gene that is induced by DNA damage and certain other stresses. Like another p53-regulated gene, p21WAF1/CIP1, whose product binds to cyclin-dependent kinases (Cdk's) and proliferating cell nuclear antigen (PCNA), GADD45 has been associated with growth suppression. Gadd45 was found to bind to PCNA, a normal component of Cdk complexes and a protein involved in DNA replication and repair. Gadd45 stimulated DNA excision repair in vitro and inhibited entry of cells into S phase. These results establish GADD45 as a link between the p53-dependent cell cycle checkpoint and DNA repair.

Authors
Smith, ML; Chen, IT; Zhan, Q; Bae, I; Chen, CY; Gilmer, TM; Kastan, MB; O'Connor, PM; Fornace, AJ
MLA Citation
Smith, ML, Chen, IT, Zhan, Q, Bae, I, Chen, CY, Gilmer, TM, Kastan, MB, O'Connor, PM, and Fornace, AJ. "Interaction of the p53-regulated protein Gadd45 with proliferating cell nuclear antigen." Science 266.5189 (November 25, 1994): 1376-1380.
PMID
7973727
Source
pubmed
Published In
Science
Volume
266
Issue
5189
Publish Date
1994
Start Page
1376
End Page
1380

The p53-dependent G1 cell cycle checkpoint pathway and ataxia-telangiectasia.

The p53 protein is a critical participant in a signal transduction pathway which mediates a G1 cell cycle arrest and apoptotic cell death in mammalian cells after ionizing irradiation. Cells from patients with the cancer-prone, radiation-sensitive disorder, ataxia-telangiectasia (AT), exhibit suboptimal (delayed and/or defective) induction of p53 protein after ionizing radiation with some dependence on dose. Other protein products which participate in this signal transduction pathway, including p21WAF1/CIP1, Gadd45, and Mdm2, are also suboptimally induced in AT cells after ionizing radiation. Induction of p53 is also abnormal in AT cells following treatment with methylmethanesulfonate and bleomycin but appears relatively normal following treatment with UV-C irradiation or the topoisomerase inhibitors, etoposide and camptothecin. These results demonstrate a specific defect in this p53-dependent signal transduction pathway in AT cells. Potential models for this observed specificity of the AT defect as measured by p53 induction include problems with responses to: (a) single-strand, but not double-strand, DNA breaks; or (b) chemically, but not enzymatically, generated DNA ends.

Authors
Canman, CE; Wolff, AC; Chen, CY; Fornace, AJ; Kastan, MB
MLA Citation
Canman, CE, Wolff, AC, Chen, CY, Fornace, AJ, and Kastan, MB. "The p53-dependent G1 cell cycle checkpoint pathway and ataxia-telangiectasia." Cancer Res 54.19 (October 1, 1994): 5054-5058.
PMID
7923116
Source
pubmed
Published In
Cancer Research
Volume
54
Issue
19
Publish Date
1994
Start Page
5054
End Page
5058

p53-dependent G1 arrest involves pRB-related proteins and is disrupted by the human papillomavirus 16 E7 oncoprotein.

The cell cycle regulatory tumor suppressor proteins p53 and pRB are targeted for inactivation by several tumor viruses, including the high-risk types of human papillomaviruses (HPVs) via interactions of the HPV E6 and E7 oncoproteins with p53 and pRB, respectively. p53 plays a central role in a signal transduction pathway that mediates G1 arrest after DNA damage, though the mechanism by which G1 arrest occurs has not been elucidated. The cyclin-associated protein p21waf1/cip1 has recently been shown to be induced by p53 and to inhibit cyclin complex-mediated phosphorylation of pRB in vitro. Thus, we investigated a possible role for pRB in the p53-mediated DNA damage response. After gamma-irradiation, cells expressing wild-type p53 arrested in G1, contained increased levels of WAF1/CIP1 mRNA, and demonstrated accumulation of hypophosphorylated pRB. In contrast, cell lines with abnormal p53 genes or with p53 functionally inactivated by the E6 oncoprotein of HPV16 (a high-risk HPV) failed to arrest in G1, did not elevate WAF1/CIP1 mRNA, and did not accumulate hypophosphorylated pRB. Despite apparently normal elevation of p53 protein and WAF1/CIP1 mRNA after irradiation, cells expressing HPV16 E7 also failed to arrest in G1 and did not accumulate hypophosphorylated pRB. Disruption of RB genes alone did not totally abrogate this G1 arrest. Our results suggest that p53 indirectly regulates phosphorylation of pRB and that pRB and/or other pRB-like molecules that bind to HPV16 E7 participate in the DNA damage-mediated G1 arrest signal. In the process of HPV infection, the HPV E6 and E7 oncoproteins may undermine this cell cycle checkpoint, contributing to the accumulation of genetic alterations during tumorigenesis.

Authors
Slebos, RJ; Lee, MH; Plunkett, BS; Kessis, TD; Williams, BO; Jacks, T; Hedrick, L; Kastan, MB; Cho, KR
MLA Citation
Slebos, RJ, Lee, MH, Plunkett, BS, Kessis, TD, Williams, BO, Jacks, T, Hedrick, L, Kastan, MB, and Cho, KR. "p53-dependent G1 arrest involves pRB-related proteins and is disrupted by the human papillomavirus 16 E7 oncoprotein." Proc Natl Acad Sci U S A 91.12 (June 7, 1994): 5320-5324.
PMID
8202487
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
91
Issue
12
Publish Date
1994
Start Page
5320
End Page
5324

The p53-dependent gamma-ray response of GADD45.

Activation of the human GADD45 gene by ionizing radiation (IR) has previously been shown to be dependent on the tumor suppressor and transcription factor p53 (M. B. Kastan, et al., Cell 71: 587-597, 1992). Unlike GADD45, the response of other DNA damage-inducible genes to IR is not dependent on p53 based on the observation that induction in a panel of cell lines did not correlate with a normal p53 status; this included human GADD153, another member of the gadd (growth arrest and DNA damage inducible) group; MyD118, a gene related to GADD45; and the protooncogenes c-jun and c-fos. This p53-dependent response of GADD45 was further investigated in human cells with halogenated pyrimidines, which act as radiosensitizers when incorporated into cellular DNA. When cellular DNA contained halogenated pyrimidines such as iododeoxyuridine (IdUrd), GADD45 gamma-ray induction, as measured by increased mRNA, was enhanced. Rapid induction could be seen with doses as low as 0.5 Gy, and substitution with IdUrd resulted in an approximately 2-fold increase in induction over a wide dose range. This level of IdUrd substitution produced a similar fold increase in cellular radiosensitivity and has been shown previously (T. M. Kinsella et al., Int. J. Radiation Oncology Biol. Phys. 13: 733-739, 1987) to produce a similar fold increase in DNA strand breaks after IR. Considering that substitution with halogenated pyrimidines would be expected to have little effect on other cellular targets after IR, these experiments indicate that actual damage to DNA, primarily strand breaks, is a major signal for the activation of this p53-dependent pathway that is required for GADD45 induction and for activation of the G1 "checkpoint" cell cycle delay.

Authors
Zhan, Q; Bae, I; Kastan, MB; Fornace, AJ
MLA Citation
Zhan, Q, Bae, I, Kastan, MB, and Fornace, AJ. "The p53-dependent gamma-ray response of GADD45." Cancer Res 54.10 (May 15, 1994): 2755-2760.
PMID
8168107
Source
pubmed
Published In
Cancer Research
Volume
54
Issue
10
Publish Date
1994
Start Page
2755
End Page
2760

Interactions between p53 and MDM2 in a mammalian cell cycle checkpoint pathway.

Normal p53 function is required for optimal arrest of cells in the G1 phase of the cell cycle following certain types of DNA damage. Loss of this cell cycle checkpoint may contribute to tumor development by increasing the number of genetic abnormalities in daughter cells following DNA damage. The MDM2 protein is an endogenous gene product that binds to the p53 protein and is able to block p53-mediated transactivation of cotransfected reporter constructs; thus, interactions between MDM2 and p53 in this checkpoint pathway following ionizing irradiation were examined. Though increases in p53 protein by DNA damage were not abrogated by MDM2 overexpression, increased levels of MDM2, resulting either from endogenous gene amplification or from transfection of an exogenous expression vector, were associated with a reduction in the ability of cells to arrest in G1 following irradiation. In addition, expression of endogenous MDM2 was enhanced by ionizing irradiation at the level of transcription in a p53-dependent fashion. These observations demonstrate that MDM2 overexpression can inhibit p53 function in a known physiologic pathway and are consistent with the hypothesis that MDM2 may function in a "feedback loop" mechanism with p53, possibly acting to limit the length or severity of the p53-mediated arrest following DNA damage.

Authors
Chen, CY; Oliner, JD; Zhan, Q; Fornace, AJ; Vogelstein, B; Kastan, MB
MLA Citation
Chen, CY, Oliner, JD, Zhan, Q, Fornace, AJ, Vogelstein, B, and Kastan, MB. "Interactions between p53 and MDM2 in a mammalian cell cycle checkpoint pathway." Proc Natl Acad Sci U S A 91.7 (March 29, 1994): 2684-2688.
PMID
8146175
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
91
Issue
7
Publish Date
1994
Start Page
2684
End Page
2688

DNA strand breaks: the DNA template alterations that trigger p53-dependent DNA damage response pathways.

The tumor suppressor protein p53 serves as a critical regulator of a G1 cell cycle checkpoint and of apoptosis following exposure of cells to DNA-damaging agents. The mechanism by which DNA-damaging agents elevate p53 protein levels to trigger G1/S arrest or cell death remains to be elucidated. In fact, whether damage to the DNA template itself participates in transducing the signal leading to p53 induction has not yet been demonstrated. We exposed human cell lines containing wild-type p53 alleles to several different DNA-damaging agents and found that agents which rapidly induce DNA strand breaks, such as ionizing radiation, bleomycin, and DNA topoisomerase-targeted drugs, rapidly triggered p53 protein elevations. In addition, we determined that camptothecin-stimulated trapping of topoisomerase I-DNA complexes was not sufficient to elevate p53 protein levels; rather, replication-associated DNA strand breaks were required. Furthermore, treatment of cells with the antimetabolite N(phosphonoacetyl)-L-aspartate (PALA) did not cause rapid p53 protein increases but resulted in delayed increases in p53 protein levels temporally correlated with the appearance of DNA strand breaks. Finally, we concluded that DNA strand breaks were sufficient for initiating p53-dependent signal transduction after finding that introduction of nucleases into cells by electroporation stimulated rapid p53 protein elevations. While DNA strand breaks appeared to be capable of triggering p53 induction, DNA lesions other than strand breaks did not. Exposure of normal cells and excision repair-deficient xeroderma pigmentosum cells to low doses of UV light, under conditions in which thymine dimers appear but DNA replication-associated strand breaks were prevented, resulted in p53 induction attributable to DNA strand breaks associated with excision repair. Our data indicate that DNA strand breaks are sufficient and probably necessary for p53 induction in cells with wild-type p53 alleles exposed to DNA-damaging agents.

Authors
Nelson, WG; Kastan, MB
MLA Citation
Nelson, WG, and Kastan, MB. "DNA strand breaks: the DNA template alterations that trigger p53-dependent DNA damage response pathways." Mol Cell Biol 14.3 (March 1994): 1815-1823.
PMID
8114714
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
14
Issue
3
Publish Date
1994
Start Page
1815
End Page
1823

P53 AND OTHER MOLECULAR CONTROLS OF THE RESPONSE TO DNA-DAMAGE

Authors
KASTAN, MB; NELSON, WG; CHEN, CY; SLICHENMYER, WB
MLA Citation
KASTAN, MB, NELSON, WG, CHEN, CY, and SLICHENMYER, WB. "P53 AND OTHER MOLECULAR CONTROLS OF THE RESPONSE TO DNA-DAMAGE." JOURNAL OF CELLULAR BIOCHEMISTRY (February 13, 1994): 164-164.
Source
wos-lite
Published In
Journal of Cellular Biochemistry
Publish Date
1994
Start Page
164
End Page
164

P53 AND OTHER MOLECULAR CONTROLS OF THE RESPONSE TO DNA-DAMAGE

Authors
KASTAN, MB; NELSON, WG; CHEN, CY; SLICHENMYER, WB
MLA Citation
KASTAN, MB, NELSON, WG, CHEN, CY, and SLICHENMYER, WB. "P53 AND OTHER MOLECULAR CONTROLS OF THE RESPONSE TO DNA-DAMAGE." JOURNAL OF CELLULAR BIOCHEMISTRY (February 13, 1994): 209-209.
Source
wos-lite
Published In
Journal of Cellular Biochemistry
Publish Date
1994
Start Page
209
End Page
209

Resolution of nephrocalcinosis associated with tumor lysis syndrome.

Authors
Wechsler, DS; Kastan, MB; Fivush, BA
MLA Citation
Wechsler, DS, Kastan, MB, and Fivush, BA. "Resolution of nephrocalcinosis associated with tumor lysis syndrome." Pediatr Hematol Oncol 11.1 (January 1994): 115-118. (Letter)
PMID
8155494
Source
pubmed
Published In
Pediatric Hematology-Oncology (Informa)
Volume
11
Issue
1
Publish Date
1994
Start Page
115
End Page
118

WAF1/CIP1 is induced in p53-mediated G1 arrest and apoptosis

The tumor growth suppressor WAF1/CIP1 was recently shown to be induced by p53 and to be a potent inhibitor of cyclin-dependent kinases. In the present studies, we sought to determine the relationship between the expression of WAF1/CIP1 and endogenous regulation of p53 function. WAF1/CIP1 protein was first localized to the nucleus of cells containing wild-type p53 and undergoing G1 arrest. WAF1/CIP1 was induced in wild-type p53-containing cells by exposure to DNA damaging agents, but not in mutant p53-containing cells. The induction of WAF1/CIP1 protein occurred in cells undergoing either p53-associated G1 arrest or apoptosis but not in cells induced to arrest in G1 or to undergo apoptosis through p53-independent mechanisms. DNA damage led to increased levels of WAF1/CIP1 in cyclin E-containing complexes and to an associated decrease in cyclin-dependent kinase activity. These results support the idea that WAF1/CIP1 is a critical downstream effector in the p53- specific pathway of growth control in mammalian cells.

Authors
El-Deiry, WS; Harper, JW; O'Connor, PM; Velculescu, VE; Canman, CE; Jackman, J; Pietenpol, JA; Burrell, M; Hill, DE; Wang, Y; Wiman, KG; Mercer, WE; Kastan, MB; Kohn, KW; Elledge, SJ; Kinzler, KW; Vogelstein, B
MLA Citation
El-Deiry, WS, Harper, JW, O'Connor, PM, Velculescu, VE, Canman, CE, Jackman, J, Pietenpol, JA, Burrell, M, Hill, DE, Wang, Y, Wiman, KG, Mercer, WE, Kastan, MB, Kohn, KW, Elledge, SJ, Kinzler, KW, and Vogelstein, B. "WAF1/CIP1 is induced in p53-mediated G1 arrest and apoptosis." Cancer Research 54.5 (1994): 1169-1174.
PMID
8118801
Source
scival
Published In
Cancer Research
Volume
54
Issue
5
Publish Date
1994
Start Page
1169
End Page
1174

Characterization of human Gadd45, a p53-regulated protein

GADD45 (growth arrest and DNA damage) is a DNA-damage-inducible gene regulated in part by the tumor suppressor p53. A role in negative growth control has recently been suggested based on significant (more than 75%) reduction of colony formation following over expression of Gadd45. To better understand the role of Gadd45, we have developed specific rabbit and murine antibodies raised against the human recombinant protein. Using these antibodies, we have found that in ML-1 cells Gadd45 is predominantly a nuclear protein. MyD118, a protein induced by terminal differentiation sharing 57% homology with Gadd45, does not cross-react with any of the antibodies produced. As expected, the induction of Gadd45 protein by ionizing radiation (IR) was also found to be dependent on a wild type p53 phenotype. Interestingly, WI-L2-NS, a human lymphoid cell line, showed very high basal levels of Gadd45 mRNA and protein in addition to a high constitutive level of a mutated p53 protein. In this cell line, the high levels of GADD45 did not inhibit cellular growth in spite of the fact that no mutations were found in GADD45 sequence. These results indicate that some cell line(s) can tolerate high levels of Gadd45 and abrogate its growth suppression function.

Authors
Carrier, F; Smith, ML; Bae, I; Kilpatrick, KE; Lansing, TJ; Chen-, CY; Engelstein, M; Friend, SH; Henner, WD; Gilmer, TM; Kastan, MB; Jr, AJF
MLA Citation
Carrier, F, Smith, ML, Bae, I, Kilpatrick, KE, Lansing, TJ, Chen-, CY, Engelstein, M, Friend, SH, Henner, WD, Gilmer, TM, Kastan, MB, and Jr, AJF. "Characterization of human Gadd45, a p53-regulated protein." Journal of Biological Chemistry 269.51 (1994): 32672-32677.
PMID
7798274
Source
scival
Published In
Journal of Biological Chemistry
Volume
269
Issue
51
Publish Date
1994
Start Page
32672
End Page
32677

DNA damage responses: p53 induction, cell cycle perturbations, and apoptosis.

Authors
Canman, CE; Chen, CY; Lee, MH; Kastan, MB
MLA Citation
Canman, CE, Chen, CY, Lee, MH, and Kastan, MB. "DNA damage responses: p53 induction, cell cycle perturbations, and apoptosis." Cold Spring Harb Symp Quant Biol 59 (1994): 277-286. (Review)
PMID
7587079
Source
pubmed
Published In
Cold Spring Harbor Laboratory: Symposia on Quantitative Biology
Volume
59
Publish Date
1994
Start Page
277
End Page
286

MOLECULAR CONTROLS OF CELL-CYCLE PROGRESSION FOLLOWING DNA-DAMAGE - ROLES OF P(53) AND ATAXIA-TELANGIECTASIA GENE-PRODUCTS

Authors
KASTAN, MB
MLA Citation
KASTAN, MB. "MOLECULAR CONTROLS OF CELL-CYCLE PROGRESSION FOLLOWING DNA-DAMAGE - ROLES OF P(53) AND ATAXIA-TELANGIECTASIA GENE-PRODUCTS." 1994.
Source
wos-lite
Published In
APOPTOSIS
Volume
5
Publish Date
1994
Start Page
117
End Page
135

Control of G1 arrest after DNA damage.

The temporal relationship between DNA damage and DNA replication may be critical in determining whether the genetic changes necessary for cellular transformation occur after DNA damage. Recent characterization of the mechanisms responsible for alterations in cell-cycle progression after DNA damage in our laboratory have implicated the p53 (tumor suppressor) protein in the G1 arrest that occurs after certain types of DNA damage. In particular, we found that levels of p53 protein increased rapidly and transiently after nonlethal doses of gamma irradiation (XRT) in hematopoietic cells with wild-type, but not mutant, p53 genes. These changes in p53 protein levels were temporally linked to a transient G1 arrest in these cells. Hematopoietic cells with mutant or absent p53 genes did not exhibit this G1 arrest, through they continued to demonstrate a G2 arrest. We recently extended these observations of a tight correlation between the status of the endogenous p53 genes and this G1 arrest after XRT and this cell-cycle alteration after XRT was then established by transfecting cells lacking endogenous p53 genes with a wild-type gene and observing acquisition of the G1 arrest and by transfecting cells processing endogenous wild-type p53 genes with a mutant p53 gene and observing loss of the G1 arrest after XRT. These observations and their significance for our understanding of the mechanisms of DNA damage-induced cellular transformation are discussed.

Authors
Kastan, MB; Kuerbitz, SJ
MLA Citation
Kastan, MB, and Kuerbitz, SJ. "Control of G1 arrest after DNA damage." Environ Health Perspect 101 Suppl 5 (December 1993): 55-58. (Review)
PMID
8013425
Source
pubmed
Published In
Environmental health perspectives
Volume
101 Suppl 5
Publish Date
1993
Start Page
55
End Page
58

Experimental models of human carcinogenesis.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "Experimental models of human carcinogenesis." Nat Genet 5.3 (November 1993): 207-208.
PMID
8275078
Source
pubmed
Published In
Nature Genetics
Volume
5
Issue
3
Publish Date
1993
Start Page
207
End Page
208
DOI
10.1038/ng1193-207

HOT PAPERS - ONCOLOGY - PARTICIPATION OF P53 PROTEIN IN THE CELLULAR-RESPONSE TO DNA-DAMAGE BY KASTAN,M.B., ONYEKWERE,O., SIDRANSKY,D., ET-AL

Authors
KASTAN, MB
MLA Citation
KASTAN, MB. "HOT PAPERS - ONCOLOGY - PARTICIPATION OF P53 PROTEIN IN THE CELLULAR-RESPONSE TO DNA-DAMAGE BY KASTAN,M.B., ONYEKWERE,O., SIDRANSKY,D., ET-AL." SCIENTIST 7.18 (September 20, 1993): 16-16.
Source
wos-lite
Published In
Scientist (Philadelphia, Pa.)
Volume
7
Issue
18
Publish Date
1993
Start Page
16
End Page
16

Loss of a p53-associated G1 checkpoint does not decrease cell survival following DNA damage.

Cell cycle checkpoints regulate progression through the cell cycle. In yeast, loss of the G2 checkpoint by mutation of the rad9 gene results in increased genetic instability as well as increased sensitivity to ionizing radiation. In contrast, comparing clonogenic survival of cells which are isogeneic except for p53 functional status, we find that loss of a G1 checkpoint in mammalian cells is not associated with increased sensitivity to the lethal effects of ionizing radiation or a topoisomerase I inhibitor, camptothecin. These results indicate that increased sensitivity to DNA-damaging agents is not necessarily a defining feature of a mammalian cell cycle checkpoint. Furthermore, in light of a recent link of p53 function to radiation-induced apoptosis in hematopoietic cells, these observations suggest that p53-dependent apoptosis is a cell type-specific phenomenon and thus predict that the biological consequences of loss of p53 function will be cell type specific.

Authors
Slichenmyer, WJ; Nelson, WG; Slebos, RJ; Kastan, MB
MLA Citation
Slichenmyer, WJ, Nelson, WG, Slebos, RJ, and Kastan, MB. "Loss of a p53-associated G1 checkpoint does not decrease cell survival following DNA damage." Cancer Res 53.18 (September 15, 1993): 4164-4168.
PMID
8364909
Source
pubmed
Published In
Cancer Research
Volume
53
Issue
18
Publish Date
1993
Start Page
4164
End Page
4168

Human papillomavirus 16 E6 expression disrupts the p53-mediated cellular response to DNA damage.

Infection with certain types of human papillomaviruses (HPV) is highly associated with carcinomas of the human uterine cervix. However, HPV infection alone does not appear to be sufficient for the process of malignant transformation, suggesting the requirement of additional cellular events. After DNA damage, normal mammalian cells exhibit G1 cell-cycle arrest and inhibition of replicative DNA synthesis. This mechanism, which requires wild-type p53, presumably allows cells to undertake DNA repair and avoid the fixation of mutations. We directly tested whether the normal response of cervical epithelial cells to DNA damage may be undermined by interactions between the E6 protein expressed by oncogenic HPV types and wild-type p53. We treated primary keratinocytes with the DNA-damaging agent actinomycin D and demonstrated inhibition of replicative DNA synthesis and a significant increase in p53 protein levels. In contrast, inhibition of DNA synthesis and increases in p53 protein did not occur after actinomycin D treatment of keratinocytes immortalized with HPV16 E6/E7 or in cervical carcinoma cell lines containing HPV16, HPV18, or mutant p53 alone. To test the effects of E6 alone on the cellular response to DNA damage, HPV16 E6 was expressed in the carcinoma cell line RKO, resulting in undetectable baseline levels of p53 protein and loss of the G1 arrest that normally occurs in these cells after DNA damage. These findings demonstrate that oncogenic E6 can disrupt an important cellular response to DNA damage mediated by p53 and may contribute to the subsequent accumulation of genetic changes associated with cervical tumorigenesis.

Authors
Kessis, TD; Slebos, RJ; Nelson, WG; Kastan, MB; Plunkett, BS; Han, SM; Lorincz, AT; Hedrick, L; Cho, KR
MLA Citation
Kessis, TD, Slebos, RJ, Nelson, WG, Kastan, MB, Plunkett, BS, Han, SM, Lorincz, AT, Hedrick, L, and Cho, KR. "Human papillomavirus 16 E6 expression disrupts the p53-mediated cellular response to DNA damage." Proc Natl Acad Sci U S A 90.9 (May 1, 1993): 3988-3992.
PMID
8387205
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
90
Issue
9
Publish Date
1993
Start Page
3988
End Page
3992

Altered cytoplasmic/nuclear distribution of the c-myc protein in differentiating ML-1 human myeloid leukemia cells.

The c-myc gene is thought to play a role in cell proliferation and differentiation; for example, constitutive expression of an exogenously introduced c-myc gene can inhibit differentiation in hematopoietic cell lines. Expression of the endogenous c-myc gene has now been monitored during the differentiation, and associated loss of proliferation, of ML-1 human myeloblastic leukemia cells: c-myc mRNA remains detectable, at decreased levels, during differentiation along the monocyte/macrophage pathway induced with 12-O-tetradecanoylphorbol-13-acetate. c-myc protein also remains present, at undiminished levels, in mature, nonproliferative cells (assessed by immunoblotting and flow cytometry). The protein is, however, readily detectable in the cytoplasm of 12-O-tetradecanoylphorbol-13-acetate-induced cells, and some of this cytoplasmic c-myc exhibits a shift in electrophoretic mobility compared to the predominantly nuclear c-myc in uninduced cells. Furthermore, although c-myc protein continues to be synthesized in the mature cells (assessed by metabolic labeling/immunoprecipitation), loss of the protein from the cytoplasm and accumulation in the nucleus are slowed (assessed by pulse-chase metabolic labeling). These findings suggest that, during the 12-O-tetradecanoylphorbol-13-acetate-induced differentiation and loss of proliferation of ML-1 cells, c-myc protein is regulated through alterations that affect its cytoplasmic/nuclear distribution rather than its total cellular content.

Authors
Craig, RW; Buchan, HL; Civin, CI; Kastan, MB
MLA Citation
Craig, RW, Buchan, HL, Civin, CI, and Kastan, MB. "Altered cytoplasmic/nuclear distribution of the c-myc protein in differentiating ML-1 human myeloid leukemia cells." Cell Growth Differ 4.5 (May 1993): 349-357.
PMID
8518229
Source
pubmed
Published In
Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research
Volume
4
Issue
5
Publish Date
1993
Start Page
349
End Page
357

IDENTIFICATION OF A P53-REGULATED GENE INVOLVED IN A CELL-CYCLE CHECKPOINT ACTIVATED BY DNA DAMAGE

Authors
ZHAN, QM; KASTAN, MB; CARRIER, F; HOLLANDER, MC; FORNACE, AJ
MLA Citation
ZHAN, QM, KASTAN, MB, CARRIER, F, HOLLANDER, MC, and FORNACE, AJ. "IDENTIFICATION OF A P53-REGULATED GENE INVOLVED IN A CELL-CYCLE CHECKPOINT ACTIVATED BY DNA DAMAGE." JOURNAL OF CELLULAR BIOCHEMISTRY (January 9, 1993): 141-141.
Source
wos-lite
Published In
Journal of Cellular Biochemistry
Publish Date
1993
Start Page
141
End Page
141

Acute neurotoxicity after intrathecal cytosine arabinoside in two adolescents with acute lymphoblastic leukemia of B-cell type.

BACKGROUND: Two adolescents with acute B-cell leukemia (Burkitt leukemia) had acute severe neurotoxicity after treatment with intrathecal (IT) cytosine arabinoside (AraC) at a dose of 50 mg/day for three consecutive days. RESULTS: A 16-year-old boy had a rapidly ascending myelopathy and encephalopathy 20 hours after receiving the third dose of IT AraC. He remained quadriplegic and required ventilatory assistance for 10 months until his death from progressive tumor. A 12-year-old girl had acute encephalopathy, seizures, and focal neuroimaging abnormalities in the cerebellum and brain stem within 32 hours of the third AraC dose and 8 hours after IT methotrexate (MTX, 12 mg). Her clinical neurologic deficits resolved during the ensuing month. Patient 1 represents the first report to the authors' knowledge of acute severe neurotoxicity after AraC administered as the only IT drug. In Patient 2, IT AraC neurotoxicity may have been potentiated by the single dose of MTX. CONCLUSION: IT AraC administered for 3 or more consecutive days may lead to profound neurologic dysfunction and require discontinuation of therapy.

Authors
Resar, LM; Phillips, PC; Kastan, MB; Leventhal, BG; Bowman, PW; Civin, CI
MLA Citation
Resar, LM, Phillips, PC, Kastan, MB, Leventhal, BG, Bowman, PW, and Civin, CI. "Acute neurotoxicity after intrathecal cytosine arabinoside in two adolescents with acute lymphoblastic leukemia of B-cell type." Cancer 71.1 (January 1, 1993): 117-123.
PMID
8416707
Source
pubmed
Published In
Cancer
Volume
71
Issue
1
Publish Date
1993
Start Page
117
End Page
123

P53: a determinant of the cell cycle response to DNA damage.

Authors
Kastan, MB
MLA Citation
Kastan, MB. "P53: a determinant of the cell cycle response to DNA damage." Adv Exp Med Biol 339 (1993): 291-293.
PMID
8178724
Source
pubmed
Published In
Advances in experimental medicine and biology
Volume
339
Publish Date
1993
Start Page
291
End Page
293

Discussion of Dr. Kastan's presentation

Authors
Moran, ; Kastan, MB; DeCabrio, ; Mihich, E; Kufe,
MLA Citation
Moran, , Kastan, MB, DeCabrio, , Mihich, E, and Kufe, . "Discussion of Dr. Kastan's presentation." Advances in Experimental Medicine and Biology 339 (1993): 295-296.
Source
scival
Published In
Advances in Experimental Medicine and Biology
Volume
339
Publish Date
1993
Start Page
295
End Page
296

A mammalian cell cycle checkpoint pathway utilizing p53 and GADD45 is defective in ataxia-telangiectasia.

Cell cycle checkpoints can enhance cell survival and limit mutagenic events following DNA damage. Primary murine fibroblasts became deficient in a G1 checkpoint activated by ionizing radiation (IR) when both wild-type p53 alleles were disrupted. In addition, cells from patients with the radiosensitive, cancer-prone disease ataxia-telangiectasia (AT) lacked the IR-induced increase in p53 protein levels seen in normal cells. Finally, IR induction of the human GADD45 gene, an induction that is also defective in AT cells, was dependent on wild-type p53 function. Wild-type but not mutant p53 bound strongly to a conserved element in the GADD45 gene, and a p53-containing nuclear factor, which bound this element, was detected in extracts from irradiated cells. Thus, we identified three participants (AT gene(s), p53, and GADD45) in a signal transduction pathway that controls cell cycle arrest following DNA damage; abnormalities in this pathway probably contribute to tumor development.

Authors
Kastan, MB; Zhan, Q; el-Deiry, WS; Carrier, F; Jacks, T; Walsh, WV; Plunkett, BS; Vogelstein, B; Fornace, AJ
MLA Citation
Kastan, MB, Zhan, Q, el-Deiry, WS, Carrier, F, Jacks, T, Walsh, WV, Plunkett, BS, Vogelstein, B, and Fornace, AJ. "A mammalian cell cycle checkpoint pathway utilizing p53 and GADD45 is defective in ataxia-telangiectasia." Cell 71.4 (November 13, 1992): 587-597.
PMID
1423616
Source
pubmed
Published In
Cell
Volume
71
Issue
4
Publish Date
1992
Start Page
587
End Page
597

Wild-type p53 is a cell cycle checkpoint determinant following irradiation.

Cell cycle checkpoints appear to contribute to an increase in cell survival and a decrease in abnormal heritable genetic changes following exposure to DNA damaging agents. Though several radiation-sensitive yeast mutants have been identified, little is known about the genes that control these responses in mammalian cells. Recent studies from our laboratory have demonstrated a close correlation between expression of wild-type p53 genes in human hematopoietic cells and their ability to arrest in G1 phase after certain types of DNA damage. In the present study, this correlation was first generalized to nonhematopoietic mammalian cells as well. A cause and effect relationship between expression of wild-type p53 and the G1 arrest that occurs after gamma irradiation was then established by demonstrating (i) acquisition of the G1 arrest after gamma irradiation following transfection of wild-type p53 genes into cells lacking endogenous p53 genes and (ii) loss of the G1 arrest after irradiation following transfection of mutant p53 genes into cells with wild-type endogenous p53 genes. A defined role for p53 (the most commonly mutated gene in human cancers) in a physiologic pathway has, to our knowledge, not been reported previously. Furthermore, these experiments illustrate one way in which a mutant p53 gene product can function in a "dominant negative" manner. Participation of p53 in this pathway suggests a mechanism for the contribution of abnormalities in p53 to tumorigenesis and genetic instability and provides a useful model for studies of the molecular mechanisms of p53 involvement in controlling the cell cycle.

Authors
Kuerbitz, SJ; Plunkett, BS; Walsh, WV; Kastan, MB
MLA Citation
Kuerbitz, SJ, Plunkett, BS, Walsh, WV, and Kastan, MB. "Wild-type p53 is a cell cycle checkpoint determinant following irradiation." Proc Natl Acad Sci U S A 89.16 (August 15, 1992): 7491-7495.
PMID
1323840
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
89
Issue
16
Publish Date
1992
Start Page
7491
End Page
7495

Participation of p53 protein in the cellular response to DNA damage.

The inhibition of replicative DNA synthesis that follows DNA damage may be critical for avoiding genetic lesions that could contribute to cellular transformation. Exposure of ML-1 myeloblastic leukemia cells to nonlethal doses of the DNA damaging agents, gamma-irradiation or actinomycin D, causes a transient inhibition of replicative DNA synthesis via both G1 and G2 arrests. Levels of p53 protein in ML-1 cells and in proliferating normal bone marrow myeloid progenitor cells increase and decrease in temporal association with the G1 arrest. In contrast, the S-phase arrest of ML-1 cells caused by exposure to the anti-metabolite, cytosine arabinoside, which does not directly damage DNA, is not associated with a significant change in p53 protein levels. Caffeine treatment blocks both the G1 arrest and the induction of p53 protein after gamma-irradiation, thus suggesting that blocking the induction of p53 protein may contribute to the previously observed effects of caffeine on cell cycle changes after DNA damage. Unlike ML-1 cells and normal bone marrow myeloid progenitor cells, hematopoietic cells that either lack p53 gene expression or overexpress a mutant form of the p53 gene do not exhibit a G1 arrest after gamma-irradiation; however, the G2 arrest is unaffected by the status of the p53 gene. These results suggest a role for the wild-type p53 protein in the inhibition of DNA synthesis that follows DNA damage and thus suggest a new mechanism for how the loss of wild-type p53 might contribute to tumorigenesis.

Authors
Kastan, MB; Onyekwere, O; Sidransky, D; Vogelstein, B; Craig, RW
MLA Citation
Kastan, MB, Onyekwere, O, Sidransky, D, Vogelstein, B, and Craig, RW. "Participation of p53 protein in the cellular response to DNA damage." Cancer Res 51.23 Pt 1 (December 1, 1991): 6304-6311.
PMID
1933891
Source
pubmed
Published In
Cancer Research
Volume
51
Issue
23 Pt 1
Publish Date
1991
Start Page
6304
End Page
6311

Levels of p53 protein increase with maturation in human hematopoietic cells.

Transfection of the wild-type p53 gene into malignant cell lines usually results in an inhibition of proliferation. However, the physiological function of the endogenous p53 gene product has been difficult to ascertain. In order to examine whether p53 is involved in the regulation of proliferation and/or differentiation of hematopoietic tissue, we modified a recently developed flow cytometric assay to assess p53 protein expression in normal human hematopoietic cells, primary leukemias, and selected leukemia cell lines. In normal human bone marrow, p53 protein was not detected in the proliferative, progenitor cell populations identified by the cell surface antigens CD34 (progenitor cells of multiple lineages) or glycophorin (erythroid precursors). In contrast, low but detectable levels of p53 protein were observed in the nonproliferative, mature lymphoid, granulocytic, and monocytic cell populations. Similarly, p53 levels increased and DNA synthesis decreased during 12-O-tetradecanoylphorbol-13-acetate-induced differentiation of ML-1 myeloblastic leukemia cells. Both of these results suggest that endogenous, wild-type p53 protein may play a role in hematopoietic cell maturation, possibly by contributing to the inhibition of proliferation that occurs during terminal differentiation. Leukemia cells deviated from this pattern of expression: (a) in contrast to the normal, proliferative bone marrow progenitor cells, a significant percentage of patient leukemia samples expressed detectable levels of p53 protein; and (b) leukemia cell lines exhibited lineage-specific abnormalities in p53 expression, with overexpression in lymphoid cell lines and lack of expression in myeloid cell lines.

Authors
Kastan, MB; Radin, AI; Kuerbitz, SJ; Onyekwere, O; Wolkow, CA; Civin, CI; Stone, KD; Woo, T; Ravindranath, Y; Craig, RW
MLA Citation
Kastan, MB, Radin, AI, Kuerbitz, SJ, Onyekwere, O, Wolkow, CA, Civin, CI, Stone, KD, Woo, T, Ravindranath, Y, and Craig, RW. "Levels of p53 protein increase with maturation in human hematopoietic cells." Cancer Res 51.16 (August 15, 1991): 4279-4286.
PMID
1868448
Source
pubmed
Published In
Cancer Research
Volume
51
Issue
16
Publish Date
1991
Start Page
4279
End Page
4286

Topoisomerase II levels during granulocytic maturation in vitro and in vivo.

Western blotting, indirect immunolocalization, flow cytometry, and a functional assay for drug-induced strand breakage were utilized to examine topoisomerase (topo) II levels during granulocytic maturation in HL-60 human progranulocytic leukemia cells and in samples of normal human marrow. Indirect immunofluorescence revealed that the intensity of the signal for topo II in unsynchronized log phase HL-60 cells varied widely. Indirect immunolabeling combined with propidium iodide staining and two-parameter flow cytometry revealed that topo II levels increased an average of 2-fold as cells progressed from G1 to G2/M. When HL-60 cells were induced to mature toward granulocytes, topo II levels progressively decreased and became undetectable by functional assays, by indirect immunoperoxidase staining, and by Western blotting with an antibody which identified Mr 170,000 and Mr 180,000 forms of topo II. Similar changes were detected during normal granulocytic maturation in human marrow in vivo. Western blotting revealed that levels of the Mr 170,000 (proliferation-associated) isoform of topo II were highest in marrow fractions enriched in progranulocytes and myelocytes, intermediate in unfractionated marrow from normal volunteers, and undetectable in mature granulocytes. The Mr 180,000 topo II polypeptide was also diminished or absent from mature granulocytes. In further experiments, marrow samples from normal volunteers were subjected to flow cytometry after labeling of topo II and various cell surface markers. Levels of the Mr 170,000 topo II polypeptide in CD34-positive cells (multipotent and committed progenitors from several hematopoietic lineages) were indistinguishable from levels observed in the HL-60 leukemia cell line. These results suggest that topo II levels in highly proliferative normal human myeloid cells in vivo approach levels found in corresponding neoplastic cell lines in vitro. Conversely, as the same cells mature into granulocytes in vivo or in vitro, levels of both molecular weight forms of topo II diminish. These results provide a framework for the further investigation of topo II levels and drug sensitivity in human leukemia.

Authors
Kaufmann, SH; McLaughlin, SJ; Kastan, MB; Liu, LF; Karp, JE; Burke, PJ
MLA Citation
Kaufmann, SH, McLaughlin, SJ, Kastan, MB, Liu, LF, Karp, JE, and Burke, PJ. "Topoisomerase II levels during granulocytic maturation in vitro and in vivo." Cancer Res 51.13 (July 1, 1991): 3534-3543.
PMID
1647269
Source
pubmed
Published In
Cancer Research
Volume
51
Issue
13
Publish Date
1991
Start Page
3534
End Page
3543

Normal human bone marrow precursors that express terminal deoxynucleotidyl transferase include T-cell precursors and possible lymphoid stem cells.

To compare the differentiation of early B- and T-lymphoid precursors, we have used immune adherence combined with analytical flow cytometric techniques to enrich and characterize subsets of the small population of bone marrow mononuclear cells that express the enzyme terminal deoxynucleotidyl transferase (TdT) but lack the CD19 B-lymphoid marker. Two percent to five percent of bone marrow TdT + mononuclear cells belong to the T-lymphoid lineage by virtue of expression of CD7 or CD5. Three-color immunofluorescence studies showed that, like early B-lymphoid precursors, most bone marrow TdT + T cells express HLA-DR and the progenitor cell antigen CD34, and about half express CD10. All CD5 + TdT + cells express surface CD3 and T-cell receptor alpha, beta, while a subset of CD7 + TdT + cells lack these "mature" T cell features. CD2 is low or absent on CD5 + TdT + cells. Examination of isolated CD34 + cells showed that approximately 70% of CD34 + TdT + cells expressed neither CD19, CD22, CD7, nor CD5, and 15% to 50% also lacked CD10. Thus, a major subset of CD34 + TdT + cells lack lineage-specific surface antigens. TdT expression may be the earliest available marker of lymphoid differentiation, and CD34 + TdT + cells are likely to include progenitor cells for both the B and T lineages.

Authors
Gore, SD; Kastan, MB; Civin, CI
MLA Citation
Gore, SD, Kastan, MB, and Civin, CI. "Normal human bone marrow precursors that express terminal deoxynucleotidyl transferase include T-cell precursors and possible lymphoid stem cells." Blood 77.8 (April 15, 1991): 1681-1690.
PMID
2015396
Source
pubmed
Published In
Blood
Volume
77
Issue
8
Publish Date
1991
Start Page
1681
End Page
1690

Participation of p53 protein in the cellular response to DNA damage

The inhibition of replicative DNA synthesis that follows DNA damage may be critical for avoiding genetic lesions that could contribute to cellular transformation. Exposure of ML-1 myeloblastic leukemia cells to non-lethal doses of the DNA damaging agents, γ-irradiation or actinomycin D, causes a transient inhibition of replicative DNA synthesis via both G1 and G2 arrests. Levels of p53 protein in ML-1 cells and in proliferating normal bone marrow myeloid progenitor cells increase and decrease in temporal association with the G1 arrest. In contrast, the S-phase arrest of ML-1 cells caused by exposure to the anti-metabolite, cytosine arabinoside, which does not directly damage DNA, is not associated with a significant change in p53 protein levels. Caffeine treatment blocks both the G1 arrest and the induction of p53 protein after γ-irradiation, thus suggesting that blocking the induction of p53 protein may contribute to the previously observed effects of caffeine on cell cycle changes after DNA damage. Unlike ML-1 cells and normal bone marrow myeloid progenitor cells, hematopoietic cells that either lack p53 gene expression or overexpress a mutant form of the p53 gene do not exhibit a G1 arrest after γ-irradiation; however, the G2 arrest is unaffected by the status of the p53 gene. These results suggest a role for the wild-type p53 protein in the inhibition of DNA synthesis that follows DNA damage and thus suggest a new mechanism for how the loss of wild-type p53 might contribute to tumorigenesis.

Authors
Kastan, MB; Onyekwere, O; Sidransky, D; Vogelstein, B; Craig, RW
MLA Citation
Kastan, MB, Onyekwere, O, Sidransky, D, Vogelstein, B, and Craig, RW. "Participation of p53 protein in the cellular response to DNA damage." Cancer Research 51.23 (1991): 6304-6311.
Source
scival
Published In
Cancer Research
Volume
51
Issue
23
Publish Date
1991
Start Page
6304
End Page
6311

Levels of p53 protein increase with maturation in human hematopoietic cells

Authors
KASTAN, M
MLA Citation
KASTAN, M. "Levels of p53 protein increase with maturation in human hematopoietic cells." Cancer Res. 51 (1991): 4279-4286.
Source
cinii-english
Published In
Cancer Res.
Volume
51
Publish Date
1991
Start Page
4279
End Page
4286

Detection of minimal residual T cell acute lymphoblastic leukemia by flow cytometry.

We have developed a flow cytometric assay for the determination of cellular expression of terminal deoxynucleotidyl transferase (TdT) and applied this to the detection of minimal residual T cell acute lymphoblastic leukemia (T-ALL). The flow cytometric assay for TdT demonstrated requisite specificity: TdT was localized to the nucleus, and was detected in MOLT3 T lymphoblasts, clinical T-ALL samples, and normal bone marrow B lymphoid precursors, but in neither the KG1a myeloid leukemia cell line nor normal myeloid cells. Co-expression of TdT and the pan T cell marker CD5 was used to quantify T lymphoblasts. 0.25 +/- 0.13% of normal adult bone marrow CD5+ cells were TdT+; these may represent early T lymphoid precursors. When admixed with normal bone marrow, CD5+TdT+ leukemic cells could be detected above background levels at an added concentration of 0.035% (95% confidence interval 0.028-0.43%). Long term follow-up of a large number of patients will be required to determine the clinical significance of a minimal burden of leukemic cells.

Authors
Gore, SD; Kastan, MB; Goodman, SN; Civin, CI
MLA Citation
Gore, SD, Kastan, MB, Goodman, SN, and Civin, CI. "Detection of minimal residual T cell acute lymphoblastic leukemia by flow cytometry." J Immunol Methods 132.2 (September 14, 1990): 275-286.
PMID
1698878
Source
pubmed
Published In
Journal of Immunological Methods
Volume
132
Issue
2
Publish Date
1990
Start Page
275
End Page
286

Direct demonstration of elevated aldehyde dehydrogenase in human hematopoietic progenitor cells.

Relative levels of cytoplasmic aldehyde dehydrogenase (ALDH) were determined in selected subpopulations of normal human bone marrow cells using a flow cytometric assay that simultaneously detects a cell surface antigen (as a marker of cell lineage and developmental stage) and the level of ALDH. The intracellular level of this enzyme has been shown to be directly related to cellular resistance to activated cyclophosphamide and is believed to be important in the survival of cells capable of repopulating marrow in autologous bone marrow transplant procedures. Western blot analysis and flow cytometric analysis of four murine cell lines with known ALDH levels were used to establish the relation between ALDH content and fluorescence with an affinity-purified anti-mouse ALDH antibody. An affinity purified anti-human ALDH antibody, characterized by immunoblotting of cytosolic extracts of cell lines with known ALDH content, was used to determine relative ALDH levels in the marrow subpopulations. We found that hematopoietic progenitor cells express the highest level of ALDH, while lymphocytes express the lowest level. Immature erythroid cells express ALDH at a level intermediate between progenitor cells and lymphocytes.

Authors
Kastan, MB; Schlaffer, E; Russo, JE; Colvin, OM; Civin, CI; Hilton, J
MLA Citation
Kastan, MB, Schlaffer, E, Russo, JE, Colvin, OM, Civin, CI, and Hilton, J. "Direct demonstration of elevated aldehyde dehydrogenase in human hematopoietic progenitor cells." Blood 75.10 (May 15, 1990): 1947-1950.
PMID
2337669
Source
pubmed
Published In
Blood
Volume
75
Issue
10
Publish Date
1990
Start Page
1947
End Page
1950

Acute leukemia in children.

Authors
Kastan, MB; Civin, CI
MLA Citation
Kastan, MB, and Civin, CI. "Acute leukemia in children." Curr Opin Oncol 2.1 (February 1990): 34-40. (Review)
PMID
2095231
Source
pubmed
Published In
Current Opinion in Oncology
Volume
2
Issue
1
Publish Date
1990
Start Page
34
End Page
40

Flow cytometric ientification of intracellular antigens: Detection of minimal residual leukemia

Authors
Gore, S; Kastan, M; Civin, C
MLA Citation
Gore, S, Kastan, M, and Civin, C. "Flow cytometric ientification of intracellular antigens: Detection of minimal residual leukemia." Bone Marrow Transplantation 6.SUPPL. 1 (1990): 39-41.
PMID
1697192
Source
scival
Published In
Bone Marrow Transplantation
Volume
6
Issue
SUPPL. 1
Publish Date
1990
Start Page
39
End Page
41

Nuclear oncoprotein expression as a function of lineage, differentiation stage, and proliferative status of normal human hematopoietic cells.

Relative levels of the nuclear oncoproteins c-myb, c-myc, and c-fos were determined in selected subpopulations of normal human bone marrow (BM) cells using a flow cytometric assay which simultaneously detects a cell-surface antigen (as a marker of lineage and stage of maturation) and levels of an intracellular protein. At least two monoclonal antibodies directed against each oncoprotein and specific peptide inhibition controls were used for these determinations. Hematopoietic progenitor cells (CD34+) express the highest levels of c-myb and c-myc, whereas c-fos levels in CD34+ progenitor cells are similar to c-fos levels in mature monocytes and granulocytes. Granulocytes are the only hematopoietic cells examined which do not express detectable levels of c-myb and c-myc. The levels of these oncoproteins in these normal, unstimulated BM cell populations were more closely linked to lineage and maturation stage than to the proliferative status of the given population, as determined by either DNA staining or expression of the cell-cycle specific nuclear protein, Ki67. This flow cytometric assay helps in interpreting the significance of oncoprotein levels in leukemia cells by allowing direct comparisons of a leukemia with the phenotypically similar "normal counterpart control" cell population in normal BM.

Authors
Kastan, MB; Stone, KD; Civin, CI
MLA Citation
Kastan, MB, Stone, KD, and Civin, CI. "Nuclear oncoprotein expression as a function of lineage, differentiation stage, and proliferative status of normal human hematopoietic cells." Blood 74.5 (October 1989): 1517-1524.
PMID
2506946
Source
pubmed
Published In
Blood
Volume
74
Issue
5
Publish Date
1989
Start Page
1517
End Page
1524

Expression of protooncogene c-myb in normal human hematopoietic cells.

Expression of the protooncogene, c-myb, in various subpopulations of normal human hematopoietic cells was characterized. Cells expressing the immature cell surface marker, CD34 (My10), were isolated by immune adherence with the "panning" technique or immunomagnetic microspheres and were shown to be strongly positive for c-myb protein expression in an immunoperoxidase assay. The CD34+ progenitor cell population was further separated into myeloid plus erythroid progenitors (CD34+, CD10-) v B-lymphoid precursors (coexpressing CD34 and CD10) by two-color FACS. Both CD34+ progenitor cell subsets strongly expressed c-myb protein by the immunoperoxidase assay. A flow cytometric assay was then developed which permitted simultaneous detection of a cell-surface antigen (to characterize lineage and stage of maturation) and the nuclear oncoprotein. This assay confirmed that CD34+ cells were strongly positive for c-myb expression and also allowed quantitative comparisons of c-myb expression in selected populations of other normal hematopoietic cells. Most human bone marrow cells appear to express some level of c-myb protein, although the CD34+ progenitor cell population expresses the highest amount.

Authors
Kastan, MB; Slamon, DJ; Civin, CI
MLA Citation
Kastan, MB, Slamon, DJ, and Civin, CI. "Expression of protooncogene c-myb in normal human hematopoietic cells." Blood 73.6 (May 1, 1989): 1444-1451.
PMID
2469491
Source
pubmed
Published In
Blood
Volume
73
Issue
6
Publish Date
1989
Start Page
1444
End Page
1451

Philadelphia-chromosome positive essential thrombocythemia. Two cases in children.

Two cases of children with essential thrombocythemia (ET) with the presence of a Philadelphia chromosome (Ph1) are presented and discussed. Diagnosis was based on their clinical presentation and marked primary thrombocytosis. The site of the Ph1 translocation, as detected by a 1.2-kb bcr genomic probe, differed in the two patients. These cases, along with other reported cases of Ph1-positive ET in the literature, suggest that the presence of the Ph1 cannot be used to rule out a diagnosis of ET. Additionally, the differing translocation sites in these cases suggests that the exact translocation site may not be significant in determining which cell lineage will predominate in a Ph1-positive myeloproliferative disorder.

Authors
Kastan, MB; Zehnbauer, BA; Leventhal, BG; Corden, BJ; Dover, GJ
MLA Citation
Kastan, MB, Zehnbauer, BA, Leventhal, BG, Corden, BJ, and Dover, GJ. "Philadelphia-chromosome positive essential thrombocythemia. Two cases in children." Am J Pediatr Hematol Oncol 11.4 (1989): 433-436.
PMID
2618978
Source
pubmed
Published In
American Journal of Pediatric Hematology/Oncology
Volume
11
Issue
4
Publish Date
1989
Start Page
433
End Page
436

The role of hematopoietic growth factors and oncogenes in leukemogenesis.

Understanding of the roles and molecular mechanisms of hematopoietic growth factors has increased greatly in recent years. This past decade has also brought us tantalizingly close to linking a group of genes normally involved in the regulation of growth and differentiation--the cellular proto-oncogenes--to the process of malignant transformation. In this article, we review the known actions of hematopoietic growth factors in normal hematopoiesis and in hematologic malignancies. We then discuss current concepts of the roles of proto-oncogenes in normal cells and their potential involvement in leukemogenic events. A merging of these concepts with classical hypotheses of multistage carcinogenesis is emphasized.

Authors
Kastan, MB; Strauss, LC; Civin, CI
MLA Citation
Kastan, MB, Strauss, LC, and Civin, CI. "The role of hematopoietic growth factors and oncogenes in leukemogenesis." Am J Pediatr Hematol Oncol 11.3 (1989): 249-267. (Review)
PMID
2675658
Source
pubmed
Published In
American Journal of Pediatric Hematology/Oncology
Volume
11
Issue
3
Publish Date
1989
Start Page
249
End Page
267

PROTO-ONCOGENE C-MYB IS EXPRESSED IN NORMAL HUMAN HEMATOPOIETIC PROGENITOR CELLS

Authors
KASTAN, MB; SLAMON, DJ; CIVIN, CL
MLA Citation
KASTAN, MB, SLAMON, DJ, and CIVIN, CL. "PROTO-ONCOGENE C-MYB IS EXPRESSED IN NORMAL HUMAN HEMATOPOIETIC PROGENITOR CELLS." EXPERIMENTAL HEMATOLOGY 16.6 (July 1988): 507-507.
Source
wos-lite
Published In
Experimental Hematology
Volume
16
Issue
6
Publish Date
1988
Start Page
507
End Page
507

Distribution of 5-methyldeoxycytidine in products of staphylococcal nuclease digestion of nuclei and purified DNA.

We have compared the distribution of 5-methyldeoxycytidine (m5dC) between staphylococcal nuclease (SN) sensitive and resistant regions of human diploid fibroblast chromatin to the corresponding distribution in purified DNA. After SN digestion of fibroblast nuclei or purified DNA, nuclease-resistant products were separated from sensitive products by perchloric acid or ethanol precipitation; the radioactively labeled nucleosides were then fractionated by high-performance liquid chromatography and quantitated. Our results indicate that m5dC is preferentially associated with SN-resistant regions of both chromatin and purified DNA. The magnitudes of these preferences in fibroblast chromatin and DNA are similar; we find that the enrichment of m5dC content in SN-resistant fractions of nuclei and DNA relative to the corresponding sensitive fractions is approximately 2-3-fold. Therefore, highly methylated regions of DNA have an intrinsic resistance to digestion by SN that is of sufficient magnitude to explain the high degree of nuclease resistance of chromatin containing highly methylated DNA.

Authors
Barr, FG; Kastan, MB; Lieberman, MW
MLA Citation
Barr, FG, Kastan, MB, and Lieberman, MW. "Distribution of 5-methyldeoxycytidine in products of staphylococcal nuclease digestion of nuclei and purified DNA." Biochemistry 24.6 (March 12, 1985): 1424-1428.
PMID
3986183
Source
pubmed
Published In
Biochemistry
Volume
24
Issue
6
Publish Date
1985
Start Page
1424
End Page
1428

Distribution of 5-methyldeoxycytidine in products of staphylococcal nuclease digestion of nuclei and purified DNA

Authors
Barr, FG; Kastan, MB; Lieberman, MW
MLA Citation
Barr, FG, Kastan, MB, and Lieberman, MW. "Distribution of 5-methyldeoxycytidine in products of staphylococcal nuclease digestion of nuclei and purified DNA." Federation Proceedings 43.7 (1984): no.-3560.
Source
scival
Published In
Federation Proceedings
Volume
43
Issue
7
Publish Date
1984
Start Page
no.
End Page
3560

METHYLATION OF DEOXYCYTIDINE INCORPORATED BY REPAIR SYNTHESIS FOLLOWING DAMAGE WITH ULTRAVIOLET-RADIATION AND CHEMICAL CARCINOGENS

Authors
LIEBERMAN, MW; KASTAN, MB; BARR, FG
MLA Citation
LIEBERMAN, MW, KASTAN, MB, and BARR, FG. "METHYLATION OF DEOXYCYTIDINE INCORPORATED BY REPAIR SYNTHESIS FOLLOWING DAMAGE WITH ULTRAVIOLET-RADIATION AND CHEMICAL CARCINOGENS." PROCEEDINGS OF THE AMERICAN ASSOCIATION FOR CANCER RESEARCH 24.MAR (1983): 335-335.
Source
wos-lite
Published In
Proceedings of the Annual Meeting- American Association for Cancer Research
Volume
24
Issue
MAR
Publish Date
1983
Start Page
335
End Page
335

Methylation of deoxycytidine incorporated by excision-repair synthesis of DNA.

Methylation of deoxycytidine incorporated by DNA excision-repair was studied in human diploid fibroblasts following damage with ultraviolet radiation, N-methyl-N-nitrosourea, or N-acetoxy-2-acetylaminofluorene. In confluent, nondividing cells, methylation in repair patches induced by all three agents is slow and incomplete. Whereas after DNA replication in logarithmic-phase cultures a steady state level of 3.4% 5-methylcytosine is reached in less than 2 hr after cells are labeled with 6- 3H-deoxycytidine, following ultraviolet-stimulated repair synthesis in confluent cells it takes about 3 days to reach a level of approximately 2.0% 5-methylcytosine in the repair patch. In cells from cultures in logarithmic-phase growth, 5-methylcytosine formation in ultraviolet-induced repair patches occurs faster and to a greater extent, reaching a level of approximately 2.7% in 10-20 hr. Preexisting hypomethylated repair patches in confluent cells are methylated further when the cells are stimulated to divide; however, the repair patch may still not be fully methylated before cell division occurs. Thus DNA damage and repair may lead to heritable loss of methylation at some sites.

Authors
Kastan, MB; Gowans, BJ; Lieberman, MW
MLA Citation
Kastan, MB, Gowans, BJ, and Lieberman, MW. "Methylation of deoxycytidine incorporated by excision-repair synthesis of DNA." Cell 30.2 (September 1982): 509-516.
PMID
7139710
Source
pubmed
Published In
Cell
Volume
30
Issue
2
Publish Date
1982
Start Page
509
End Page
516

Distribution of repair-incorporated nucleotides and nucleosome rearrangement in the chromatin of normal and xeroderma pigmentosum human fibroblasts.

Authors
Smerdon, MJ; Kastan, MB; Lieberman, MW
MLA Citation
Smerdon, MJ, Kastan, MB, and Lieberman, MW. "Distribution of repair-incorporated nucleotides and nucleosome rearrangement in the chromatin of normal and xeroderma pigmentosum human fibroblasts." Biochemistry 18.17 (August 21, 1979): 3732-3739.
PMID
476082
Source
pubmed
Published In
Biochemistry
Volume
18
Issue
17
Publish Date
1979
Start Page
3732
End Page
3739
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