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Bachelder, Robin Elizabeth

Overview:

Targeted therapies are not available for triple-negative (TN) breast cancer (lacking Estrogen Receptor, Progesterone Receptor, and HER2). Although many women with locally advanced TN breast cancer show a partial response to neoadjuvant chemotherapy, residual tumor cells are detected in the majority of patients post-treatment. These residual tumor cells predict future tumor recurrence and patient mortality. My laboratory studies signaling pathways associated with TN breast cancer chemotherapy resistance/tumor recurrence. Our goal is to identify novel proteins that: 1) drive TN breast cancer chemo-resistance and 2) can be targeted to eliminate chemo-resistant TN tumor cells. Ultimately, it is our goal to develop combination therapies that prevent TN tumor recurrence and improve patient survival.

The Bachelder laboratory has developed a short-term chemotherapy treatment model for studying triple-negative breast cancer chemo-resistance. In this model, short-term chemotherapy treatment of TN tumor cells enriches for dormant, chemotherapy-resistant tumor cells, representing only 0.1% of the original tumor cell population. Upon removing chemotherapy, these dormant tumor cells resume growth, establishing proliferative colonies. This model resembles recurrent tumor growth observed in cancer patients after completion of chemotherapy treatment. Using this model, we have identified novel signaling pathways contributing to TN breast cancer chemo-resistance.

Project 1: Nuclear Fibroblast growth factor signaling in TN breast cancer recurrence:

Our studies indicate that chemotherapy-enriched, dormant tumor cells express significantly increased levels of a nuclear basic FGF (bFGF) isoform (compared to parental cells). Reducing nuclear bFGF expression in dormant tumor cells decreases cell survival and inhibits colony formation upon chemotherapy removal. Nuclear bFGF maintains dormant tumor cell survival by driving transcription of DNA-dependent protein kinase, a kinase important for double-stranded DNA repair. In collaboration with Kelly Marcom, M.D. we have shown that residual tumor cells from neoadjuvant chemotherapy-treated TN breast cancer patients show increased % nuclear bFGF-positive tumor cells, validating our in vitro model. Currently, we are addressing the hypothesis that a nuclear bFGF receptor cooperates with nuclear bFGF to drive chemo-resistance. This receptor could be targeted with established FGFR inhibitors to eliminate chemo-residual TN tumor cells. 

Project 2: Interleukin 6 (IL6) signaling in TN breast cancer chemo-resistance: 

Microarray analysis indicates that chemo-residual tumor cells emanating from our short term chemotherapy treatment model express increased Interleukin 6, as well as increased IL6 receptor (gp130). Our studies indicate that these chemo-residual tumor cells support autocrine IL6 signaling that drives constitutively Stat3 activity. Furthermore, we have shown that an FDA-approved IL6 receptor-blocking antibody (Tocilizumab, Genetech), eliminates chemo-resistant tumor cells from our short-term chemotherapy treatment model by inhibiting Stat 3. We are currently designing clinical trials to test efficacy of a novel combination therapy (chemotherapy + IL6R-blocking antibody) for TN breast cancer. 

Project 3: Targeting prostate cancer stem-like cells through cell surface-expressed GRP78:

We are collaborating with Salvatore Pizzo, M.D., Ph.D. and Ashley Chi, M.D. to investigate the importance of cell surface GRP78 for prostate cancer stem-like cell growth. In addition to being an endoplasmic reticulum chaperone protein, glucose-regulated protein of 78 kDa (GRP78) is expressed on the surface of tumor cells, where it orchestrates numerous signaling pathways. Cell surface GRP78 is an ideal therapeutic target for these cancers because it promotes tumor cell survival and is not detected in normal tissues. Our studies show that short-term chemotherapy treatment of prostate tumor cells enriches for a prostate cancer stem-like cell population that expresses cell surface GRP78. Preliminary studies indicate that GRP78-neutralizing antibodies inhibit human prostate cancer stem-like cell growth. We plan to test the impact of these GRP78-neutralizing antibodies on human androgen-independent prostate cancer growth using an animal model. 

Positions:

Associate Professor in Pathology

Pathology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 1995

Ph.D. — Harvard University

Grants:

Targeting precursor neural (N)-cadherin to eliminate chemotherapy-resistant triple-negative breast tumor cells

Administered By
Pathology
AwardedBy
Department of Defense
Role
Principal Investigator
Start Date
March 01, 2017
End Date
February 29, 2020

Targeting nuclear FGF receptor to improve chemotherapy response in triple-negative breast cancer

Administered By
Pathology
AwardedBy
Department of Defense
Role
Principal Investigator
Start Date
September 30, 2013
End Date
September 29, 2016

Nuclear Snail-1 in the progression of Estrogen Receptor(-) invasive breast cancer

Administered By
Pathology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
March 01, 2011
End Date
February 28, 2013

Novel Function for VEGF in Breast Carcinoma Survival

Administered By
Pathology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2002
End Date
June 30, 2008
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Publications:

Chemotherapy enriches for an invasive triple-negative breast tumor cell subpopulation expressing a precursor form of N-cadherin on the cell surface.

Although most triple-negative breast cancer (TNBC) patients initially respond to chemotherapy, residual tumor cells frequently persist and drive recurrent tumor growth. Previous studies from our laboratory and others' indicate that TNBC is heterogeneous, being composed of chemo-sensitive and chemo-resistant tumor cell subpopulations. In the current work, we studied the invasive behaviors of chemo-resistant TNBC, and sought to identify markers of invasion in chemo-residual TNBC.The invasive behavior of TNBC tumor cells surviving short-term chemotherapy treatment in vitro was studied using transwell invasion assays and an experimental metastasis model. mRNA expression levels of neural cadherin (N-cadherin), an adhesion molecule that promotes invasion, was assessed by PCR. Expression of N-cadherin and its precursor form (pro-N-cadherin) was assessed by immunoblotting and flow cytometry. Pro-N-cadherin immunohistochemistry was performed on tumors obtained from patients pre- and post- neoadjuvant chemotherapy treatment.TNBC cells surviving short-term chemotherapy treatment exhibited increased invasive behavior and capacity to colonize metastatic sites compared to untreated tumor cells. The invasive behavior of chemo-resistant cells was associated with their increased cell surface expression of precursor N-cadherin (pro-N-cadherin). An antibody specific for the precursor domain of N-cadherin inhibited invasion of chemo-resistant TNBC cells. To begin to validate our findings in humans, we showed that the percent cell surface pro-N-cadherin (+) tumor cells increased in patients post- chemotherapy treatment.TNBC cells surviving short-term chemotherapy treatment are more invasive than bulk tumor cells. Cell surface pro-N-cadherin expression is associated with the invasive and chemo-resistant behaviors of this tumor cell subset. Our findings indicate the importance of future studies determining the value of cell surface pro-N-cadherin as: 1) a biomarker for TNBC recurrence and 2) a therapeutic target for eliminating chemo-residual disease.

Authors
Nelson, ER; Li, S; Kennedy, M; Payne, S; Kilibarda, K; Groth, J; Bowie, M; Parilla-Castellar, E; de Ridder, G; Marcom, PK; Lyes, M; Peterson, BL; Cook, M; Pizzo, SV; McDonnell, DP; Bachelder, RE
MLA Citation
Nelson, ER, Li, S, Kennedy, M, Payne, S, Kilibarda, K, Groth, J, Bowie, M, Parilla-Castellar, E, de Ridder, G, Marcom, PK, Lyes, M, Peterson, BL, Cook, M, Pizzo, SV, McDonnell, DP, and Bachelder, RE. "Chemotherapy enriches for an invasive triple-negative breast tumor cell subpopulation expressing a precursor form of N-cadherin on the cell surface." Oncotarget 7.51 (December 2016): 84030-84042.
PMID
27768598
Source
epmc
Published In
Oncotarget
Volume
7
Issue
51
Publish Date
2016
Start Page
84030
End Page
84042
DOI
10.18632/oncotarget.12767

Nuclear basic fibroblast growth factor regulates triple-negative breast cancer chemo-resistance.

Chemotherapy remains the only available treatment for triple-negative (TN) breast cancer, and most patients exhibit an incomplete pathologic response. Half of patients exhibiting an incomplete pathologic response die within five years of treatment due to chemo-resistant, recurrent tumor growth. Defining molecules responsible for TN breast cancer chemo-resistance is crucial for developing effective combination therapies blocking tumor recurrence. Historically, chemo-resistance studies have relied on long-term chemotherapy selection models that drive genetic mutations conferring cell survival. Other models suggest that tumors are heterogeneous, being composed of both chemo-sensitive and chemo-resistant tumor cell populations. We previously described a short-term chemotherapy treatment model that enriches for chemo-residual TN tumor cells. In the current work, we use this enrichment strategy to identify a novel determinant of TN breast cancer chemotherapy resistance [a nuclear isoform of basic fibroblast growth factor (bFGF)].Studies are conducted using our in vitro model of chemotherapy resistance. Short-term chemotherapy treatment enriches for a chemo-residual TN subpopulation that over time resumes proliferation. By western blotting and real-time polymerase chain reaction, we show that this chemotherapy-enriched tumor cell subpopulation expresses nuclear bFGF. The importance of bFGF for survival of these chemo-residual cells is interrogated using short hairpin knockdown strategies. DNA repair capability is assessed by comet assay. Immunohistochemistry (IHC) is used to determine nuclear bFGF expression in TN breast cancer cases pre- and post- neoadjuvant chemotherapy.TN tumor cells surviving short-term chemotherapy treatment express increased nuclear bFGF. bFGF knockdown reduces the number of chemo-residual TN tumor cells. Adding back a nuclear bFGF construct to bFGF knockdown cells restores their chemo-resistance. Nuclear bFGF-mediated chemo-resistance is associated with increased DNA-dependent protein kinase (DNA-PK) expression and accelerated DNA repair. In fifty-six percent of matched TN breast cancer cases, percent nuclear bFGF-positive tumor cells either increases or remains the same post- neoadjuvant chemotherapy treatment (compared to pre-treatment). These data indicate that in a subset of TN breast cancers, chemotherapy enriches for nuclear bFGF-expressing tumor cells.These studies identify nuclear bFGF as a protein in a subset of TN breast cancers that likely contributes to drug resistance following standard chemotherapy treatment.

Authors
Li, S; Payne, S; Wang, F; Claus, P; Su, Z; Groth, J; Geradts, J; de Ridder, G; Alvarez, R; Marcom, PK; Pizzo, SV; Bachelder, RE
MLA Citation
Li, S, Payne, S, Wang, F, Claus, P, Su, Z, Groth, J, Geradts, J, de Ridder, G, Alvarez, R, Marcom, PK, Pizzo, SV, and Bachelder, RE. "Nuclear basic fibroblast growth factor regulates triple-negative breast cancer chemo-resistance." Breast cancer research : BCR 17 (July 4, 2015): 91-.
PMID
26141457
Source
epmc
Published In
Breast Cancer Research
Volume
17
Publish Date
2015
Start Page
91
DOI
10.1186/s13058-015-0590-3

Syngeneic Murine Ovarian Cancer Model Reveals That Ascites Enriches for Ovarian Cancer Stem-Like Cells Expressing Membrane GRP78.

Patients with ovarian cancer are generally diagnosed at FIGO (International Federation of Gynecology and Obstetrics) stage III/IV, when ascites is common. The volume of ascites correlates positively with the extent of metastasis and negatively with prognosis. Membrane GRP78, a stress-inducible endoplasmic reticulum chaperone that is also expressed on the plasma membrane ((mem)GRP78) of aggressive cancer cells, plays a crucial role in the embryonic stem cell maintenance. We studied the effects of ascites on ovarian cancer stem-like cells using a syngeneic mouse model. Our study demonstrates that ascites-derived tumor cells from mice injected intraperitoneally with murine ovarian cancer cells (ID8) express increased (mem)GRP78 levels compared with ID8 cells from normal culture. We hypothesized that these ascites-associated (mem)GRP78(+) cells are cancer stem-like cells (CSC). Supporting this hypothesis, we show that (mem)GRP78(+) cells isolated from murine ascites exhibit increased sphere forming and tumor initiating abilities compared with (mem)GRP78(-) cells. When the tumor microenvironment is recapitulated by adding ascites fluid to cell culture, ID8 cells express more (mem)GRP78 and increased self-renewing ability compared with those cultured in medium alone. Moreover, compared with their counterparts cultured in normal medium, ID8 cells cultured in ascites, or isolated from ascites, show increased stem cell marker expression. Antibodies directed against the carboxy-terminal domain of GRP78: (i) reduce self-renewing ability of murine and human ovarian cancer cells preincubated with ascites and (ii) suppress a GSK3α-AKT/SNAI1 signaling axis in these cells. Based on these data, we suggest that (mem)GRP78 is a logical therapeutic target for late-stage ovarian cancer.

Authors
Mo, L; Bachelder, RE; Kennedy, M; Chen, P-H; Chi, J-T; Berchuck, A; Cianciolo, G; Pizzo, SV
MLA Citation
Mo, L, Bachelder, RE, Kennedy, M, Chen, P-H, Chi, J-T, Berchuck, A, Cianciolo, G, and Pizzo, SV. "Syngeneic Murine Ovarian Cancer Model Reveals That Ascites Enriches for Ovarian Cancer Stem-Like Cells Expressing Membrane GRP78." Molecular cancer therapeutics 14.3 (March 2015): 747-756.
PMID
25589495
Source
epmc
Published In
Molecular cancer therapeutics
Volume
14
Issue
3
Publish Date
2015
Start Page
747
End Page
756
DOI
10.1158/1535-7163.mct-14-0579

Ascites Increases Expression/Function of Multidrug Resistance Proteins in Ovarian Cancer Cells.

Chemotherapy resistance is the major reason for the failure of ovarian cancer treatment. One mechanism behind chemo-resistance involves the upregulation of multidrug resistance (MDR) genes (ABC transporters) that effectively transport (efflux) drugs out of the tumor cells. As a common symptom in stage III/IV ovarian cancer patients, ascites is associated with cancer progression. However, whether ascites drives multidrug resistance in ovarian cancer cells awaits elucidation. Here, we demonstrate that when cultured with ascites derived from ovarian cancer-bearing mice, a murine ovarian cancer cell line became less sensitive to paclitaxel, a first line chemotherapeutic agent for ovarian cancer patients. Moreover, incubation of murine ovarian cancer cells in vitro with ascites drives efflux function in these cells. Functional studies show ascites-driven efflux is suppressible by specific inhibitors of either of two ABC transporters [Multidrug Related Protein (MRP1); Breast Cancer Related Protein (BCRP)]. To demonstrate relevance of our findings to ovarian cancer patients, we studied relative efflux in human ovarian cancer cells obtained from either patient ascites or from primary tumor. Immortalized cell lines developed from human ascites show increased susceptibility to efflux inhibitors (MRP1, BCRP) compared to a cell line derived from a primary ovarian cancer, suggesting an association between ascites and efflux function in human ovarian cancer. Efflux in ascites-derived human ovarian cancer cells is associated with increased expression of ABC transporters compared to that in primary tumor-derived human ovarian cancer cells. Collectively, our findings identify a novel activity for ascites in promoting ovarian cancer multidrug resistance.

Authors
Mo, L; Pospichalova, V; Huang, Z; Murphy, SK; Payne, S; Wang, F; Kennedy, M; Cianciolo, GJ; Bryja, V; Pizzo, SV; Bachelder, RE
MLA Citation
Mo, L, Pospichalova, V, Huang, Z, Murphy, SK, Payne, S, Wang, F, Kennedy, M, Cianciolo, GJ, Bryja, V, Pizzo, SV, and Bachelder, RE. "Ascites Increases Expression/Function of Multidrug Resistance Proteins in Ovarian Cancer Cells." PloS one 10.7 (January 2015): e0131579-.
PMID
26148191
Source
epmc
Published In
PloS one
Volume
10
Issue
7
Publish Date
2015
Start Page
e0131579
DOI
10.1371/journal.pone.0131579

Nuclear basic fibroblast growth factor regulates triple-negative breast cancer chemo-resistance

© 2015 Li et al.Introduction: Chemotherapy remains the only available treatment for triple-negative (TN) breast cancer, and most patients exhibit an incomplete pathologic response. Half of patients exhibiting an incomplete pathologic response die within five years of treatment due to chemo-resistant, recurrent tumor growth. Defining molecules responsible for TN breast cancer chemo-resistance is crucial for developing effective combination therapies blocking tumor recurrence. Historically, chemo-resistance studies have relied on long-term chemotherapy selection models that drive genetic mutations conferring cell survival. Other models suggest that tumors are heterogeneous, being composed of both chemo-sensitive and chemo-resistant tumor cell populations. We previously described a short-term chemotherapy treatment model that enriches for chemo-residual TN tumor cells. In the current work, we use this enrichment strategy to identify a novel determinant of TN breast cancer chemotherapy resistance [a nuclear isoform of basic fibroblast growth factor (bFGF)]. Methods: Studies are conducted using our in vitro model of chemotherapy resistance. Short-term chemotherapy treatment enriches for a chemo-residual TN subpopulation that over time resumes proliferation. By western blotting and real-time polymerase chain reaction, we show that this chemotherapy-enriched tumor cell subpopulation expresses nuclear bFGF. The importance of bFGF for survival of these chemo-residual cells is interrogated using short hairpin knockdown strategies. DNA repair capability is assessed by comet assay. Immunohistochemistry (IHC) is used to determine nuclear bFGF expression in TN breast cancer cases pre- and post- neoadjuvant chemotherapy. Results: TN tumor cells surviving short-term chemotherapy treatment express increased nuclear bFGF. bFGF knockdown reduces the number of chemo-residual TN tumor cells. Adding back a nuclear bFGF construct to bFGF knockdown cells restores their chemo-resistance. Nuclear bFGF-mediated chemo-resistance is associated with increased DNA-dependent protein kinase (DNA-PK) expression and accelerated DNA repair. In fifty-six percent of matched TN breast cancer cases, percent nuclear bFGF-positive tumor cells either increases or remains the same post- neoadjuvant chemotherapy treatment (compared to pre-treatment). These data indicate that in a subset of TN breast cancers, chemotherapy enriches for nuclear bFGF-expressing tumor cells. Conclusion: These studies identify nuclear bFGF as a protein in a subset of TN breast cancers that likely contributes to drug resistance following standard chemotherapy treatment.

Authors
Li, S; Payne, S; Wang, F; Claus, P; Su, Z; Groth, J; Geradts, J; Ridder, GD; Alvarez, R; Marcom, PK; Pizzo, SV; Bachelder, RE
MLA Citation
Li, S, Payne, S, Wang, F, Claus, P, Su, Z, Groth, J, Geradts, J, Ridder, GD, Alvarez, R, Marcom, PK, Pizzo, SV, and Bachelder, RE. "Nuclear basic fibroblast growth factor regulates triple-negative breast cancer chemo-resistance." Breast Cancer Research (2015).
Source
scival
Published In
Breast Cancer Research
Publish Date
2015
DOI
10.1186/s13058-015-0590-3

Model of tumor dormancy/recurrence after short-term chemotherapy.

Although many tumors regress in response to neoadjuvant chemotherapy, residual tumor cells are detected in most cancer patients post-treatment. These residual tumor cells are thought to remain dormant for years before resuming growth, resulting in tumor recurrence. Considering that recurrent tumors are most often responsible for patient mortality, there exists an urgent need to study signaling pathways that drive tumor dormancy/recurrence. We have developed an in vitro model of tumor dormancy/recurrence. Short-term exposure of tumor cells (breast or prostate) to chemotherapy at clinically relevant doses enriches for a dormant tumor cell population. Several days after removing chemotherapy, dormant tumor cells regain proliferative ability and establish colonies, resembling tumor recurrence. Tumor cells from "recurrent" colonies exhibit increased chemotherapy resistance, similar to the therapy resistance of recurrent tumors in cancer patients. Previous studies using long-term chemotherapy selection models identified acquired mutations that drive tumor resistance. In contrast, our short term chemotherapy exposure model enriches for a slow-cycling, dormant, chemo-resistant tumor cell sub-population that can resume growth after drug removal. Studying unique signaling pathways in dormant tumor cells enriched by short-term chemotherapy treatment is expected to identify novel therapeutic targets for preventing tumor recurrence.

Authors
Li, S; Kennedy, M; Payne, S; Kennedy, K; Seewaldt, VL; Pizzo, SV; Bachelder, RE
MLA Citation
Li, S, Kennedy, M, Payne, S, Kennedy, K, Seewaldt, VL, Pizzo, SV, and Bachelder, RE. "Model of tumor dormancy/recurrence after short-term chemotherapy." PloS one 9.5 (January 2014): e98021-.
PMID
24845582
Source
epmc
Published In
PloS one
Volume
9
Issue
5
Publish Date
2014
Start Page
e98021
DOI
10.1371/journal.pone.0098021

Erratum:Nuclear Snail1 and nuclear ZEB1 protein expression in invasive and intraductal human breast carcinomas (Human Pathology (2011) 42 (1125-1131))

Authors
Geradts, J; Herreros, AGD; Su, Z; Burchette, J; Broadwater, G; Bachelder, RE
MLA Citation
Geradts, J, Herreros, AGD, Su, Z, Burchette, J, Broadwater, G, and Bachelder, RE. "Erratum:Nuclear Snail1 and nuclear ZEB1 protein expression in invasive and intraductal human breast carcinomas (Human Pathology (2011) 42 (1125-1131))." Human Pathology 43.10 (2012): 1787--.
Source
scival
Published In
Human Pathology
Volume
43
Issue
10
Publish Date
2012
Start Page
1787-
DOI
10.1016/j.humpath.2012.07.001

Evidence for phenotypic plasticity in aggressive triple-negative breast cancer: human biology is recapitulated by a novel model system.

Breast cancers with a basal-like gene signature are primarily triple-negative, frequently metastatic, and carry a poor prognosis. Basal-like breast cancers are enriched for markers of breast cancer stem cells as well as markers of epithelial-mesenchymal transition (EMT). While EMT is generally thought to be important in the process of metastasis, in vivo evidence of EMT in human disease remains rare. Here we report a novel model of human triple-negative breast cancer, the DKAT cell line, which was isolated from an aggressive, treatment-resistant triple-negative breast cancer that demonstrated morphological and biochemical evidence suggestive of phenotypic plasticity in the patient. The DKAT cell line displays a basal-like phenotype in vitro when cultured in serum-free media, and undergoes phenotypic changes consistent with EMT/MET in response to serum-containing media, a unique property among the breast cancer cell lines we tested. This EMT is marked by increased expression of the transcription factor Zeb1, and Zeb1 is required for the enhanced migratory ability of DKAT cells in the mesenchymal state. DKAT cells also express progenitor-cell markers, and single DKAT cells are able to generate tumorspheres containing both epithelial and mesenchymal cell types. In vivo, as few as ten DKAT cells are capable of forming xenograft tumors which display a range of epithelial and mesenchymal phenotypes. The DKAT model provides a novel model to study the molecular mechanisms regulating phenotypic plasticity and the aggressive biology of triple-negative breast cancers.

Authors
D'Amato, NC; Ostrander, JH; Bowie, ML; Sistrunk, C; Borowsky, A; Cardiff, RD; Bell, K; Young, LJT; Simin, K; Bachelder, RE; Delrow, J; Dawson, A; Yee, LD; Mrózek, K; Clay, TM; Osada, T; Seewaldt, VL
MLA Citation
D'Amato, NC, Ostrander, JH, Bowie, ML, Sistrunk, C, Borowsky, A, Cardiff, RD, Bell, K, Young, LJT, Simin, K, Bachelder, RE, Delrow, J, Dawson, A, Yee, LD, Mrózek, K, Clay, TM, Osada, T, and Seewaldt, VL. "Evidence for phenotypic plasticity in aggressive triple-negative breast cancer: human biology is recapitulated by a novel model system." PLoS One 7.9 (2012): e45684-.
PMID
23049838
Source
pubmed
Published In
PloS one
Volume
7
Issue
9
Publish Date
2012
Start Page
e45684
DOI
10.1371/journal.pone.0045684

Nuclear Snail1 and nuclear ZEB1 protein expression in invasive and intraductal human breast carcinomas.

Snail1 and ZEB1 are transcriptional repressors that drive tumor initiation and metastasis in animal models. Snail1 and ZEB1 are frequently coexpressed in tumor cell lines, suggesting that these factors may cooperate to promote tumor progression. However, coexpression of these transcriptional repressors in primary human cancer specimens has not been investigated. Previous studies assessed expression in primary breast cancers of Snail1 messenger RNA, which does not reflect Snail1 activity because Snail1 is subject to posttranslational modifications that inhibit its nuclear localization/activity. In the current study, using breast tumor cell lines of known Snail1 and ZEB1 expression status, we developed immunohistochemistry protocols for detecting nuclear Snail1 and nuclear ZEB1 proteins. Using these protocols, we assessed nuclear Snail1 and nuclear ZEB1 expressions in primary human breast cancers of varying subtypes (n = 78). Nuclear Snail1 and estrogen receptor α expressions were inversely associated in primary breast cancers, and nuclear Snail1 was expressed in approximately 80% of triple-negative breast cancers (lacking estrogen receptor α, progesterone receptor, and human epidermal growth factor receptor 2 overexpression). In contrast, nuclear ZEB1 was expressed at a significantly lower frequency in these breast cancers. Notably, nuclear Snail1 protein was detected in 45% of ductal carcinoma in situ specimens (n = 29), raising the important possibility that nuclear Snail1 expression in early stage breast lesions may predict future development of invasive breast cancer. Collectively, our studies demonstrate frequent expression of nuclear Snail1, but not nuclear ZEB1, in invasive, triple-negative breast cancers as well as in intraductal carcinomas.

Authors
Geradts, J; de Herreros, AG; Su, Z; Burchette, J; Broadwater, G; Bachelder, RE
MLA Citation
Geradts, J, de Herreros, AG, Su, Z, Burchette, J, Broadwater, G, and Bachelder, RE. "Nuclear Snail1 and nuclear ZEB1 protein expression in invasive and intraductal human breast carcinomas." Hum Pathol 42.8 (August 2011): 1125-1131.
PMID
21315410
Source
pubmed
Published In
Human Pathology
Volume
42
Issue
8
Publish Date
2011
Start Page
1125
End Page
1131
DOI
10.1016/j.humpath.2010.11.004

Autocrine Semaphorin3A stimulates eukaryotic initiation factor 4E-dependent RhoA translation in breast tumor cells

Translation of the small G protein RhoA in neurons is regulated by the eukaryotic translation initiation factor eIF4E. Here we show that this translation factor also regulates RhoA expression and activity in breast cancer cells. The introduction of eIF4E into breast tumor cells increased RhoA protein levels, while expression of an eIF4E siRNA reduced RhoA expression. Previous studies indicate that the axon repulsion factor Semaphorin3A (Sema3A) stimulates the eIF4E-dependent translation of RhoA in neurons, and breast tumor cells support autocrine Sema3A signaling. Accordingly, we next examined if autocrine Sema3A signaling drives eIF4E-dependent RhoA translation in breast cancer cells. The incubation of breast tumor cells with recombinant Sema3A rapidly increased eIF4E activity, RhoA protein levels, and RhoA activity. This Sema3A activity was blocked in tumor cells expressing an shRNA-specific for the Sema3A receptor, Neuropilin-1 (NP-1), as well as in cells incubated with an eIF4E inhibitor. Importantly, RhoA protein levels were reduced in Sema3A shRNA-expressing compared to control shRNA-expressing breast tumor cells, demonstrating that autocrine Sema3A increases RhoA expression in breast cancer. Considering that Sema3A suppresses axon extension by stimulating RhoA translation, we next examined if the Sema3A/RhoA axis impacts breast tumor cell migration. The incubation of control breast tumor cells, but not RhoA shRNA-expressing cells, with rSema3A significantly reduced their migration. Collectively, these studies indicate that Sema3A impedes breast tumor cell migration in part by stimulating RhoA. These findings identify common signaling pathways that regulate the navigation of neurons and breast cancer cells, thus suggesting novel targets for suppressing breast tumor cell migration. © 2010 Elsevier Inc.

Authors
Pan, H; Bachelder, RE
MLA Citation
Pan, H, and Bachelder, RE. "Autocrine Semaphorin3A stimulates eukaryotic initiation factor 4E-dependent RhoA translation in breast tumor cells." Experimental Cell Research 316.17 (2010): 2825-2832.
PMID
20655307
Source
scival
Published In
Experimental Cell Research
Volume
316
Issue
17
Publish Date
2010
Start Page
2825
End Page
2832
DOI
10.1016/j.yexcr.2010.07.012

Autocrine semaphorin3A stimulates alpha2 beta1 integrin expression/function in breast tumor cells.

The axon repulsion factor semaphorin3A (SEMA3A) and its receptor neuropilin-1 (NP-1) are expressed in breast tumor cells, and function as suppressors of tumor cell migration. Based on the knowledge that both SEMA3A and the alpha2beta1 integrin suppress breast tumor cell migration, we studied the impact of SEMA3A signaling on alpha2beta1 integrin expression/function. The incubation of breast tumor cells with SEMA3A increased alpha2 and beta1 integrin levels, and stimulated tumor cell adhesion to the alpha2beta1-binding matrix protein collagen I. Conversely, reducing SEMA3A expression in breast tumor cells decreased alpha2beta1 levels and collagen adhesion. The ability of SEMA3A to increase tumor cell adhesion to collagen was dependent on both the SEMA3A receptor NP-1 and the glycogen synthase kinase-3. The incubation of breast tumor cells with SEMA3A disrupted the actin cytoskeleton, and reduced both tumor cell migratory and invasive behavior. Importantly, using an alpha2beta1-neutralizing antibody, we demonstrated that SEMA3A suppression of tumor cell migration is dependent on alpha2beta1. Our studies indicate that expression of the alpha2beta1 integrin, a suppressor of metastatic breast tumor growth, is stimulated in breast tumor cells by an autocrine SEMA3A pathway.

Authors
Pan, H; Wanami, LS; Dissanayake, TR; Bachelder, RE
MLA Citation
Pan, H, Wanami, LS, Dissanayake, TR, and Bachelder, RE. "Autocrine semaphorin3A stimulates alpha2 beta1 integrin expression/function in breast tumor cells." Breast Cancer Res Treat 118.1 (November 2009): 197-205.
PMID
18787945
Source
pubmed
Published In
Breast Cancer Research and Treatment
Volume
118
Issue
1
Publish Date
2009
Start Page
197
End Page
205
DOI
10.1007/s10549-008-0179-y

Vascular endothelial growth factor-A stimulates Snail expression in breast tumor cells: implications for tumor progression.

The E-cadherin transcriptional repressor Snail is a prognostic marker for metastatic breast carcinoma, as well as a critical determinant of tumor growth and recurrence. We define a non-angiogenic, autocrine function for the vascular endothelial growth factor-A (VEGF-A) in regulating Snail expression in breast tumor cells. The transfection of well-differentiated breast tumor cells with VEGF-A increases Snail mRNA and protein levels, resulting in reduced E-cadherin expression. Conversely, reducing endogenous VEGF-A expression in poorly differentiated breast tumor cells by siRNA transfection decreases Snail levels. Our studies demonstrate that VEGF and the VEGF receptor Neuropilin-1 increase Snail expression by suppressing the Glycogen Synthase Kinase-3 (GSK-3), an established inhibitor of Snail transcription and protein stability. The VEGF-A neutralizing antibody Avastin was recently approved by the FDA for the treatment of metastatic breast cancer. We present the provocative finding that beyond its anti-angiogenic activity, Avastin can reduce Snail expression in breast tumor cells. Collectively, this work describes a novel autocrine function for VEGF in breast tumor cells in driving the expression of Snail, a breast tumor progression factor. Based on our demonstration that Avastin reduces Snail expression in breast tumor cells, we propose that the treatment of early stage breast cancer patients with Avastin may impede tumor progression.

Authors
Wanami, LS; Chen, H-Y; Peiró, S; García de Herreros, A; Bachelder, RE
MLA Citation
Wanami, LS, Chen, H-Y, Peiró, S, García de Herreros, A, and Bachelder, RE. "Vascular endothelial growth factor-A stimulates Snail expression in breast tumor cells: implications for tumor progression." Exp Cell Res 314.13 (August 1, 2008): 2448-2453.
PMID
18554584
Source
pubmed
Published In
Experimental Cell Research
Volume
314
Issue
13
Publish Date
2008
Start Page
2448
End Page
2453
DOI
10.1016/j.yexcr.2008.05.004

The alpha6beta4 integrin can regulate ErbB-3 expression: implications for alpha6beta4 signaling and function.

The integrin alpha(6)beta(4) has been shown to facilitate key functions of carcinoma cells, including their ability to migrate, invade, and evade apoptosis. The mechanism involved seems to be a profound effect of alpha(6)beta(4) on specific signaling pathways, especially the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. An intimate relationship between alpha(6)beta(4) and growth factor receptors may explain this effect of alpha(6)beta(4) on signaling. Previously, we showed that alpha(6)beta(4) and ErbB-2 can function synergistically to activate the PI3K/Akt pathway. Given that ErbB-2 can activate PI3K only when it heterodimerizes with other members of the epidermal growth factor receptor family, these data imply that other receptors cooperate in this process. Here, we report that alpha(6)beta(4) can regulate the expression of ErbB-3 using several different models and that the consequent formation of an ErbB-2/ErbB-3 heterodimer promotes the alpha(6)beta(4)-dependent activation of PI3K/Akt and the ability of this integrin to impede apoptosis of carcinoma cells. Our data also support the hypothesis that alpha(6)beta(4) can regulate ErbB-3 expression at the translational level as evidenced by the findings that alpha(6)beta(4) does not increase ErbB-3 mRNA significantly, and that this regulation is both rapamycin sensitive and dependent on eukaryotic translation initiation factor 4E. These findings provide one mechanism to account for the activation of PI3K by alpha(6)beta(4) and they also provide insight into the regulation of ErbB-3 in carcinoma cells.

Authors
Folgiero, V; Bachelder, RE; Bon, G; Sacchi, A; Falcioni, R; Mercurio, AM
MLA Citation
Folgiero, V, Bachelder, RE, Bon, G, Sacchi, A, Falcioni, R, and Mercurio, AM. "The alpha6beta4 integrin can regulate ErbB-3 expression: implications for alpha6beta4 signaling and function." Cancer Res 67.4 (February 15, 2007): 1645-1652.
PMID
17308105
Source
pubmed
Published In
Cancer Research
Volume
67
Issue
4
Publish Date
2007
Start Page
1645
End Page
1652
DOI
10.1158/0008-5472.CAN-06-2980

Non-angiogenic functions of VEGF in breast cancer.

This review advances the hypothesis that the function of vascular endothelial growth factor (VEGF) in breast cancer is not limited to angiogenesis, and that VEGF signaling in breast carcinoma cells is important for the ability of these cells to evade apoptosis and progress towards invasive and metastatic disease. In other terms, VEGF signaling provides a selective advantage for the survival and dissemination of breast carcinoma cells that may be independent of angiogenesis. The key component of this hypothesis is that breast carcinoma cells express specific VEGF receptors and that these receptors respond to autocrine VEGF, resulting in the activation of signaling pathways that impede apoptosis and promote cell migration. A related hypothesis, which is developed in this review, is that the alpha6beta4 integrin, which has been implicated in the survival and motility of breast cancer cells, can stimulate the translation of VEGF mRNA and, consequently, autocrine VEGF signaling. These findings imply that VEGF and VEGF receptor-based therapeutics, in addition to targeting angiogenesis, may also target tumor cells directly.

Authors
Mercurio, AM; Lipscomb, EA; Bachelder, RE
MLA Citation
Mercurio, AM, Lipscomb, EA, and Bachelder, RE. "Non-angiogenic functions of VEGF in breast cancer." J Mammary Gland Biol Neoplasia 10.4 (October 2005): 283-290. (Review)
PMID
16924371
Source
pubmed
Published In
Journal of Mammary Gland Biology and Neoplasia
Volume
10
Issue
4
Publish Date
2005
Start Page
283
End Page
290
DOI
10.1007/s10911-006-9001-9

Glycogen synthase kinase-3 is an endogenous inhibitor of Snail transcription: implications for the epithelial-mesenchymal transition.

We report that the activity of glycogen synthase kinase-3 (GSK-3) is necessary for the maintenance of the epithelial architecture. Pharmacological inhibition of its activity or reducing its expression using small interfering RNAs in normal breast and skin epithelial cells results in a reduction of E-cadherin expression and a more mesenchymal morphology, both of which are features associated with an epithelial-mesenchymal transition (EMT). Importantly, GSK-3 inhibition also stimulates the transcription of Snail, a repressor of E-cadherin and an inducer of the EMT. We identify NFkappaB as a transcription factor inhibited by GSK-3 in epithelial cells that is relevant for Snail expression. These findings indicate that epithelial cells must sustain activation of a specific kinase to impede a mesenchymal transition.

Authors
Bachelder, RE; Yoon, S-O; Franci, C; de Herreros, AG; Mercurio, AM
MLA Citation
Bachelder, RE, Yoon, S-O, Franci, C, de Herreros, AG, and Mercurio, AM. "Glycogen synthase kinase-3 is an endogenous inhibitor of Snail transcription: implications for the epithelial-mesenchymal transition." J Cell Biol 168.1 (January 3, 2005): 29-33.
PMID
15631989
Source
pubmed
Published In
The Journal of Cell Biology
Volume
168
Issue
1
Publish Date
2005
Start Page
29
End Page
33
DOI
10.1083/jcb.200409067

Hypoxia-induced vascular endothelial growth factor transcription and protection from apoptosis are dependent on alpha6beta1 integrin in breast carcinoma cells.

The alpha6beta1 integrin has been implicated in breast carcinoma progression, but the mechanisms involved remain elusive. MDA-MB-435 cells engineered to be deficient in alpha6beta1 expression form primary tumors that are highly apoptotic and unable to metastasize, although they exhibit no increased apoptosis in vitro under standard culture conditions. Based on the hypothesis that alpha6beta1 is necessary for the survival of these cells in the tumor microenvironment, we report here that hypoxia protects these cells from apoptosis induced by serum deprivation and that hypoxia-mediated protection requires alpha6beta1 expression. We investigated the influence of alpha6beta1 on vascular endothelial growth factor (VEGF) expression because autocrine VEGF is necessary for the survival of serum-deprived cells in hypoxia. The results obtained indicate that alpha6beta1 is necessary for VEGF expression because the ability of hypoxia to activate HIF-1 and to stimulate VEGF transcription in MDA-MB-435 cells is dependent on alpha6beta1 expression by a mechanism that involves protein kinase C-alpha.

Authors
Chung, J; Yoon, S; Datta, K; Bachelder, RE; Mercurio, AM
MLA Citation
Chung, J, Yoon, S, Datta, K, Bachelder, RE, and Mercurio, AM. "Hypoxia-induced vascular endothelial growth factor transcription and protection from apoptosis are dependent on alpha6beta1 integrin in breast carcinoma cells." Cancer Res 64.14 (July 15, 2004): 4711-4716.
PMID
15256436
Source
pubmed
Published In
Cancer Research
Volume
64
Issue
14
Publish Date
2004
Start Page
4711
End Page
4716
DOI
10.1158/0008-5472.CAN-04-0347

Autocrine signaling in carcinoma: VEGF and the alpha6beta4 integrin.

This review highlights an emerging function for vascular endothelial growth factor (VEGF) in carcinoma and discusses mechanisms involved in the elaboration of VEGF autocrine loops. Evidence is provided that autocrine VEGF contributes to the two major components of invasive carcinoma: survival and migration. Moreover, the findings discussed support the hypothesis that carcinoma progression selects for cells that depend on VEGF as a survival factor. Furthermore, a related hypothesis, which is developed, is that the function of the alpha6beta4 integrin, which has been implicated in carcinoma progression, is linked to its ability to regulate VEGF translation and, consequently, autocrine VEGF signaling. The findings reviewed challenge the notion that the function of VEGF in cancer is limited to angiogenesis and suggest that VEGF and VEGF receptor-based therapeutics, in addition to targeting angiogenesis, may also impair tumor cell survival and invasion directly.

Authors
Mercurio, AM; Bachelder, RE; Bates, RC; Chung, J
MLA Citation
Mercurio, AM, Bachelder, RE, Bates, RC, and Chung, J. "Autocrine signaling in carcinoma: VEGF and the alpha6beta4 integrin." Semin Cancer Biol 14.2 (April 2004): 115-122. (Review)
PMID
15018895
Source
pubmed
Published In
Seminars in Cancer Biology
Volume
14
Issue
2
Publish Date
2004
Start Page
115
End Page
122
DOI
10.1016/j.semcancer.2003.09.016

Flt-1-dependent survival characterizes the epithelial-mesenchymal transition of colonic organoids.

Aberrant cell survival and resistance to apoptosis are hallmarks of tumor invasion and progression to metastatic disease, but the mechanisms involved are poorly understood. The epithelial-mesenchymal transition (EMT), a process that facilitates progression to invasive cancer, provides a superb model for studying such survival mechanisms. Here, we used a unique spheroid culture system that recapitulates the structure of the colonic epithelium and undergoes an EMT in response to cytokine stimulation to study this problem. Our data reveal that the EMT results in the increased expression of both VEGF and Flt-1, a tyrosine kinase VEGF receptor, and that the survival of these cells depends on a VEGF/Flt-1 autocrine pathway. Perturbation of Flt-1 function by either a blocking antibody or adenoviral expression of soluble Flt-1, which acts in a dominant-negative fashion, caused massive apoptosis only in cells that underwent EMT. This pathway was critical for the survival of other invasive colon carcinoma cell lines, and we observed a correlative upregulation of Flt-1 expression linked to in vivo human cancer progression. A role for Flt-1 in cell survival is unprecedented and has significant implications for Flt-1 function in tumor progression, as well as in other biological processes, including angiogenesis and development.

Authors
Bates, RC; Goldsmith, JD; Bachelder, RE; Brown, C; Shibuya, M; Oettgen, P; Mercurio, AM
MLA Citation
Bates, RC, Goldsmith, JD, Bachelder, RE, Brown, C, Shibuya, M, Oettgen, P, and Mercurio, AM. "Flt-1-dependent survival characterizes the epithelial-mesenchymal transition of colonic organoids." Curr Biol 13.19 (September 30, 2003): 1721-1727.
PMID
14521839
Source
pubmed
Published In
Current Biology
Volume
13
Issue
19
Publish Date
2003
Start Page
1721
End Page
1727

Competing autocrine pathways involving alternative neuropilin-1 ligands regulate chemotaxis of carcinoma cells.

Neuropilin-1 (NP1), in conjunction with plexins, promotes axon repulsion by binding to semaphorin 3A (SEMA3A). Although NP1 is expressed in carcinoma cells, its functions have remained elusive, and neither SEMA3A nor plexin expression has been explored in cancer. Here we provide evidence that breast carcinoma cells support an autocrine pathway involving SEMA3A, plexin-A1, and NP1 that impedes their ability to chemotax. Reducing SEMA3A or NP1 expression by RNA interference or inhibiting plexin-A1 signaling enhanced migration. Conversely, expression of constitutively active plexin-A1 impaired chemotaxis. The paradox of how breast carcinoma cells expressing these endogenous chemotaxis inhibitors are able to migrate is explained by their expression of vascular endothelial growth factor (VEGF), a NP1 ligand that competes with SEMA3A for receptor binding. Finally, we establish that the ratio of endogenous VEGF and SEMA3A concentrations in carcinoma cells determines their chemotactic rate. Our findings lead to the surprising conclusion that opposing autocrine loops involving NP1 regulate the chemotaxis of breast carcinoma cells. Moreover, our data indicate a novel autocrine function for VEGF in chemotaxis.

Authors
Bachelder, RE; Lipscomb, EA; Lin, X; Wendt, MA; Chadborn, NH; Eickholt, BJ; Mercurio, AM
MLA Citation
Bachelder, RE, Lipscomb, EA, Lin, X, Wendt, MA, Chadborn, NH, Eickholt, BJ, and Mercurio, AM. "Competing autocrine pathways involving alternative neuropilin-1 ligands regulate chemotaxis of carcinoma cells." Cancer Res 63.17 (September 1, 2003): 5230-5233.
PMID
14500350
Source
pubmed
Published In
Cancer Research
Volume
63
Issue
17
Publish Date
2003
Start Page
5230
End Page
5233

Vascular endothelial growth factor promotes breast carcinoma invasion in an autocrine manner by regulating the chemokine receptor CXCR4.

We report that vascular endothelial growth factor (VEGF), a major angiogenic factor, is also arequisite autocrine factor for breast carcinoma invasion in vitro and that the VEGF receptor Neuropilin-1 but not Flt-1 is essential for this function. VEGF regulates expression of the chemokine receptor CXCR4, and this VEGF target is needed for invasion but not for cell survival. CXCR4 mediates migration of breast carcinoma cells toward stromal-derived factor-1, and this migration is dependent on autocrine VEGF. Of interest, a CXCR4-inhibitory peptide that is currently in HIV clinical trials suppressed invasion. Our findings indicate that a VEGF autocrine pathway induces chemokine receptor expression in breast carcinoma cells, thus promoting their directed migration toward specific chemokines.

Authors
Bachelder, RE; Wendt, MA; Mercurio, AM
MLA Citation
Bachelder, RE, Wendt, MA, and Mercurio, AM. "Vascular endothelial growth factor promotes breast carcinoma invasion in an autocrine manner by regulating the chemokine receptor CXCR4." Cancer Res 62.24 (December 15, 2002): 7203-7206.
PMID
12499259
Source
pubmed
Published In
Cancer Research
Volume
62
Issue
24
Publish Date
2002
Start Page
7203
End Page
7206

Integrin (alpha 6 beta 4) regulation of eIF-4E activity and VEGF translation: a survival mechanism for carcinoma cells.

We define a novel mechanism by which integrins regulate growth factor expression and the survival of carcinoma cells. Specifically, we demonstrate that the alpha 6 beta 4 integrin enhances vascular endothelial growth factor (VEGF) translation in breast carcinoma cells. The mechanism involves the ability of this integrin to stimulate the phosphorylation and inactivation of 4E-binding protein (4E-BP1), a translational repressor that inhibits the function of eukaryotic translation initiation factor 4E (eIF-4E). The regulation of 4E-BP1 phosphorylation by alpha 6 beta 4 derives from the ability of this integrin to activate the PI-3K-Akt pathway and, consequently, the rapamycin-sensitive kinase mTOR that can phosphorylate 4E-BP1. Importantly, we show that this alpha 6 beta 4-dependent regulation of VEGF translation plays an important role in the survival of metastatic breast carcinoma cells by sustaining a VEGF autocrine signaling pathway that involves activation of PI-3K and Akt. These findings reveal that integrin-mediated activation of PI-3K-Akt is amplified by integrin-stimulated VEGF expression and they provide a mechanism that substantiates the reported role of alpha 6 beta 4 in carcinoma progression.

Authors
Chung, J; Bachelder, RE; Lipscomb, EA; Shaw, LM; Mercurio, AM
MLA Citation
Chung, J, Bachelder, RE, Lipscomb, EA, Shaw, LM, and Mercurio, AM. "Integrin (alpha 6 beta 4) regulation of eIF-4E activity and VEGF translation: a survival mechanism for carcinoma cells." J Cell Biol 158.1 (July 8, 2002): 165-174.
PMID
12105188
Source
pubmed
Published In
The Journal of Cell Biology
Volume
158
Issue
1
Publish Date
2002
Start Page
165
End Page
174
DOI
10.1083/jcb.200112015

The cleavage of Akt/protein kinase B by death receptor signaling is an important event in detachment-induced apoptosis.

Epithelial cells undergo death receptor-dependent apoptosis when detached from matrix, a process termed anoikis. Activation of Akt/protein kinase B (PKB) by matrix attachment protects cells from anoikis. In this study, we establish a link between anoikis and Akt/PKB-mediated survival by demonstrating that Akt/PKB is cleaved by caspases in matrix-detached epithelial cells by a mechanism that involves death receptors. Reduced levels of Akt/PKB protein were observed in detached Madin-Darby canine kidney cells relative to cells attached to collagen. Equivalent levels of Akt/PKB, however, were detected in matrix-adherent and detached cells after inhibition of caspase activity or expression of an Akt/PKB mutant (D108+119A) that is resistant to caspase cleavage. The contribution of death domain-containing proteins to Akt/PKB cleavage was evidenced by the ability of dominant negative Fas-associated death domain to restore normal levels of Akt/PKB in matrix-detached cells. Importantly, expression of a cleavage-resistant Akt/PKB mutant protected matrix-detached cells from apoptosis. These studies suggest that members of the death receptor family promote the caspase-mediated cleavage of Akt/PKB and that this event contributes to anoikis.

Authors
Bachelder, RE; Wendt, MA; Fujita, N; Tsuruo, T; Mercurio, AM
MLA Citation
Bachelder, RE, Wendt, MA, Fujita, N, Tsuruo, T, and Mercurio, AM. "The cleavage of Akt/protein kinase B by death receptor signaling is an important event in detachment-induced apoptosis." J Biol Chem 276.37 (September 14, 2001): 34702-34707.
PMID
11463786
Source
pubmed
Published In
The Journal of biological chemistry
Volume
276
Issue
37
Publish Date
2001
Start Page
34702
End Page
34707
DOI
10.1074/jbc.M102806200

Vascular endothelial growth factor is an autocrine survival factor for neuropilin-expressing breast carcinoma cells.

We identify a novel function for the vascular endothelial growth factor (VEGF) in its ability to stimulate an autocrine signaling pathway in metastatic breast carcinoma cells that is essential for their survival. Suppression of VEGF expression in metastatic cells in vitro induced their apoptosis, in addition to inhibiting the constitutively elevated phosphatidylinositol 3'-kinase activity that is characteristic of these cells and important for their survival. Hypoxia enhanced the survival of metastatic cells by increasing VEGF expression. The importance of the VEGF receptor neuropilin was indicated by the ability of a neuropilin-binding VEGF isoform to enhance breast carcinoma survival. Moreover, the expression of neuropilin in neuropilin-deficient breast carcinoma cells protected them from apoptosis. The identification of this VEGF autocrine signaling pathway has important implications for tumor metastasis and therapeutic intervention.

Authors
Bachelder, RE; Crago, A; Chung, J; Wendt, MA; Shaw, LM; Robinson, G; Mercurio, AM
MLA Citation
Bachelder, RE, Crago, A, Chung, J, Wendt, MA, Shaw, LM, Robinson, G, and Mercurio, AM. "Vascular endothelial growth factor is an autocrine survival factor for neuropilin-expressing breast carcinoma cells." Cancer Res 61.15 (August 1, 2001): 5736-5740.
PMID
11479209
Source
pubmed
Published In
Cancer Research
Volume
61
Issue
15
Publish Date
2001
Start Page
5736
End Page
5740

Integrin laminin receptors and breast carcinoma progression.

This review explores the mechanistic basis of breast carcinoma progression by focusing on the contribution of integrins. Integrins are essential for progression not only for their ability to mediate physical interactions with extracellular matrices but also for their ability to regulate signaling pathways that control actin dynamics and cell movement, as well as for growth and survival. Our comments center on the alpha6 integrins (alpha6beta1 and alpha6beta4), which are receptors for the laminin family of basement membrane components. Numerous studies have implicated these integrins in breast cancer progression and have provided a rationale for studying the mechanistic basis of their contribution to aggressive disease. Recent work by our group and others on mechanisms of breast carcinoma invasion and survival that are influenced by the alpha6 integrins are discussed.

Authors
Mercurio, AM; Bachelder, RE; Chung, J; O'Connor, KL; Rabinovitz, I; Shaw, LM; Tani, T
MLA Citation
Mercurio, AM, Bachelder, RE, Chung, J, O'Connor, KL, Rabinovitz, I, Shaw, LM, and Tani, T. "Integrin laminin receptors and breast carcinoma progression." J Mammary Gland Biol Neoplasia 6.3 (July 2001): 299-309. (Review)
PMID
11547899
Source
pubmed
Published In
Journal of Mammary Gland Biology and Neoplasia
Volume
6
Issue
3
Publish Date
2001
Start Page
299
End Page
309

The metastatic odyssey: the integrin connection.

This article explores the mechanistic basis of carcinoma progression by focusing on the contribution of integrins. Integrins are essential for progression because of their ability to mediate physical interactions with extracellular matrices and their ability to regulate signaling pathways that control actin dynamics and cell movement, and for growth and survival. This article centers on a6 integrins (a6B1 and a6B4), which are receptors for the laminin family of basement membrane components. Numerous studies have implicated these integrins in cancer progression and have provided a rationale for studying the mechanistic basis of their contribution to aggressive disease.

Authors
Mercurio, AM; Bachelder, RE; Rabinovitz, I; O'Connor, KL; Tani, T; Shaw, LM
MLA Citation
Mercurio, AM, Bachelder, RE, Rabinovitz, I, O'Connor, KL, Tani, T, and Shaw, LM. "The metastatic odyssey: the integrin connection." Surg Oncol Clin N Am 10.2 (April 2001): 313-ix. (Review)
PMID
11382589
Source
pubmed
Published In
Surgical Oncology Clinics of North America
Volume
10
Issue
2
Publish Date
2001
Start Page
313
End Page
ix

p53 inhibits alpha 6 beta 4 integrin survival signaling by promoting the caspase 3-dependent cleavage of AKT/PKB.

Although the interaction of matrix proteins with integrins is known to initiate signaling pathways that are essential for cell survival, a role for tumor suppressors in the regulation of these pathways has not been established. We demonstrate here that p53 can inhibit the survival function of integrins by inducing the caspase-dependent cleavage and inactivation of the serine/threonine kinase AKT/PKB. Specifically, we show that the alpha6beta4 integrin promotes the survival of p53-deficient carcinoma cells by activating AKT/PKB. In contrast, this integrin does not activate AKT/PKB in carcinoma cells that express wild-type p53 and it actually stimulates their apoptosis, in agreement with our previous findings (Bachelder, R.E., A. Marchetti, R. Falcioni, S. Soddu, and A.M. Mercurio. 1999. J. Biol. Chem. 274:20733-20737). Interestingly, we observed reduced levels of AKT/PKB protein after antibody clustering of alpha6beta4 in carcinoma cells that express wild-type p53. In contrast, alpha6beta4 clustering did not reduce the level of AKT/PKB in carcinoma cells that lack functional p53. The involvement of caspase 3 in AKT/PKB regulation was indicated by the ability of Z-DEVD-FMK, a caspase 3 inhibitor, to block the alpha6beta4-associated reduction in AKT/PKB levels in vivo, and by the ability of recombinant caspase 3 to promote the cleavage of AKT/PKB in vitro. In addition, the ability of alpha6beta4 to activate AKT/PKB could be restored in p53 wild-type carcinoma cells by inhibiting caspase 3 activity. These studies demonstrate that the p53 tumor suppressor can inhibit integrin-associated survival signaling pathways.

Authors
Bachelder, RE; Ribick, MJ; Marchetti, A; Falcioni, R; Soddu, S; Davis, KR; Mercurio, AM
MLA Citation
Bachelder, RE, Ribick, MJ, Marchetti, A, Falcioni, R, Soddu, S, Davis, KR, and Mercurio, AM. "p53 inhibits alpha 6 beta 4 integrin survival signaling by promoting the caspase 3-dependent cleavage of AKT/PKB." J Cell Biol 147.5 (November 29, 1999): 1063-1072.
PMID
10579725
Source
pubmed
Published In
The Journal of Cell Biology
Volume
147
Issue
5
Publish Date
1999
Start Page
1063
End Page
1072

Activation of p53 function in carcinoma cells by the alpha6beta4 integrin.

The interaction of integrins with extracellular matrix is known to promote cell survival by inhibiting apoptotic signaling. In contrast, we demonstrate here that the alpha6beta4 integrin induces apoptosis in carcinoma cells by stimulating p53 function. Specifically, we show that expression of alpha6beta4 in carcinoma cells that lack this integrin stimulates an increase in the transactivating function of p53 as demonstrated by the ability of this integrin to up-regulate the expression of a p53-sensitive reporter gene as well as the endogenous p53 response gene, bax. In addition, we report that alpha6beta4 triggers apoptosis in carcinoma cells that express wild-type but not mutant p53 and that these alpha6beta4 functions are inhibited by a dominant negative p53 construct. Importantly, we provide a link between integrin signaling and p53 activation by demonstrating that the clustering of alpha6beta4 with a beta4 integrin-specific antibody promotes p53-dependent apoptosis in cells that express both alpha6beta4 and wild-type p53. These studies are the first to demonstrate that a specific integrin can promote apoptosis by activating p53. Moreover, given the ability of alpha6beta4 to stimulate invasion (Shaw, L. M., Rabinovitz, I., Wang, H. F., Toker, A., and Mercurio, A. M. (1997) Cell 91, 949-960), these studies suggest that the ability of alpha6beta4 to promote carcinoma progression will be enhanced in tumor cells that express mutant, inactive forms of p53.

Authors
Bachelder, RE; Marchetti, A; Falcioni, R; Soddu, S; Mercurio, AM
MLA Citation
Bachelder, RE, Marchetti, A, Falcioni, R, Soddu, S, and Mercurio, AM. "Activation of p53 function in carcinoma cells by the alpha6beta4 integrin." J Biol Chem 274.29 (July 16, 1999): 20733-20737.
PMID
10400708
Source
pubmed
Published In
The Journal of biological chemistry
Volume
274
Issue
29
Publish Date
1999
Start Page
20733
End Page
20737

Activation of p53 function in carcinoma cells by the α6β4 integrin

The interaction of integrins with extracellular matrix is known to promote cell survival by inhibiting apoptotic signaling. In contrast, we demonstrate here that the α6β4 integrin induces apoptosis in carcinoma cells by stimulating p53 function. Specifically, we show that expression of α6β4 in carcinoma cells that lack this integrin stimulates an increase in the transactivating function of p53 as demonstrated by the ability of this integrin to up-regulate the expression of a p53-sensitive reporter gene as well as the endogenous p53 response gene, bax. In addition, we report that α6β4 triggers apoptosis in carcinoma cells that express wild-type but not mutant p53 and that these α6β4 functions are inhibited by a dominant negative p53 construct. Importantly, we provide a link between integrin signaling and p53 activation by demonstrating that the clustering of α6β4 with a β4 integrin-specific antibody promotes p53-dependent apoptosis in cells that express both α6β4 and wild-type p53. These studies are the first to demonstrate that a specific integrin can promote apoptosis by activating p53. Moreover, given the ability of α6β4 to stimulate invasion (Shaw, L. M., Rabinovitz, I., Wang, H. F., Toker, A., and Mercurio, A. M. (1997) Cell 91, 949-960), these studies suggest that the ability of α6β4 to promote carcinoma progression will be enhanced in tumor cells that express mutant, inactive forms of p53.

Authors
Bachelder, RE; Marchetti, A; Falcioni, R; Soddu, S; Mercurio, AM
MLA Citation
Bachelder, RE, Marchetti, A, Falcioni, R, Soddu, S, and Mercurio, AM. "Activation of p53 function in carcinoma cells by the α6β4 integrin." Journal of Biological Chemistry 274.29 (1999): 20733-20737.
Source
scival
Published In
The Journal of biological chemistry
Volume
274
Issue
29
Publish Date
1999
Start Page
20733
End Page
20737
DOI
10.1074/jbc.274.29.20733

Postbinding functions of CD4 in HIV infection.

Several studies have suggested that the CD4 molecule, in addition to serving as the HIV receptor, may also be involved in postbinding events of HIV infection. The CD4 molecule has been shown to assume an altered conformation on the T-cell surface following HIV binding, which may be involved in these postbinding events.

Authors
Bachelder, RE; Letvin, NL
MLA Citation
Bachelder, RE, and Letvin, NL. "Postbinding functions of CD4 in HIV infection." Trends Microbiol 4.9 (September 1996): 359-363. (Review)
PMID
8885171
Source
pubmed
Published In
Trends in Microbiology
Volume
4
Issue
9
Publish Date
1996
Start Page
359
End Page
363

A human recombinant Fab identifies a human immunodeficiency virus type 1-induced conformational change in cell surface-expressed CD4.

To explore the role of the CD4 molecule in human immunodeficiency virus (HIV) infection following initial virus-CD4 binding, we have characterized CD4-specific antibodies raised by immunizing an HIV-1-infected human with human recombinant soluble CD4 (rsCD4). Fabs were selected from a human recombinant Fab library constructed from the bone marrow of this immunized individual. Here, we describe a human rsCD4-specific recombinant Fab clone selected by panning the library over complexes of human rsCD4 and recombinant HIV-1 envelope protein. While this Fab does not bind to CD4-positive T-cell lines or to human T lymphocytes, it recognizes cell surface-expressed CD4 following the incubation of these cells with a recombinant form of HIV-1 gp120 or with HIV-1 virions. The Fab is not HIV-1 envelope specific, since it does not bind to recombinant gp120 or to native cell surface-expressed HIV-1 envelope proteins. As confirmation of its CD4 specificity, we show that this Fab immunoprecipitates a 55-kDa protein, corresponding to the molecular mass of cellular CD4, from an H9 cell lysate. The specificity of this human Fab provides evidence for a virus-induced conformational change in cell surface-expressed on CD4. The characterization of this altered CD4 conformation and its effects on the host cell will be important in defining postbinding events in HIV infection.

Authors
Bachelder, RE; Bilancieri, J; Lin, W; Letvin, NL
MLA Citation
Bachelder, RE, Bilancieri, J, Lin, W, and Letvin, NL. "A human recombinant Fab identifies a human immunodeficiency virus type 1-induced conformational change in cell surface-expressed CD4." J Virol 69.9 (September 1995): 5734-5742.
PMID
7637018
Source
pubmed
Published In
Journal of virology
Volume
69
Issue
9
Publish Date
1995
Start Page
5734
End Page
5742
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Research Areas:

  • Breast
  • Breast Neoplasms
  • Cell Adhesion
  • Epithelial-Mesenchymal Transition
  • Neoplasm Invasiveness
  • Neoplasm Metastasis
  • Neoplasm Recurrence, Local
  • Signal Transduction