A Novel Association between p130(Cas) and Resistance to the Chemotherapeutic Drug Adriamycin in Human Breast Cancer Cells

Department of Microbiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
Cancer Research (Impact Factor: 9.33). 12/2008; 68(21):8796-804. DOI: 10.1158/0008-5472.CAN-08-2426
Source: PubMed


Resistance to chemotherapy remains a major obstacle for the treatment of breast cancer. Understanding the molecular mechanism(s) of resistance is crucial for the development of new effective therapies to treat this disease. This study examines the putative role of p130(Cas) (Cas) in resistance to the cytotoxic agent Adriamycin. High expression of Cas in primary breast tumors is associated with the failure to respond to the antiestrogen tamoxifen and poor prognosis, highlighting the potential clinical importance of this molecule. Here, we show a novel association between Cas and resistance to Adriamycin. We show that Cas overexpression renders MCF-7 breast cancer cells less sensitive to the growth inhibitory and proapoptotic effects of Adriamycin. The catalytic activity of the nonreceptor tyrosine kinase c-Src, but not the epidermal growth factor receptor, is critical for Cas-mediated protection from Adriamycin-induced death. The phosphorylation of Akt and extracellular signal-regulated kinase 1/2 (ERK1/2) is elevated in Cas-overexpressing cells treated with Adriamycin, whereas expression of the proapoptotic protein Bak is decreased. Conversely, Cas depletion in the more resistant T47D and MDA-MB-231 cell lines increases sensitivity to Adriamycin. Based on these data, we propose that Cas activates growth and survival pathways regulated by c-Src, Akt, and ERK1/2 that lead to the inhibition of mitochondrial-mediated apoptosis in the presence of Adriamycin. Because Cas is frequently expressed at high levels in breast cancers, these findings raise the possibility of resensitizing Cas-overexpressing tumors to chemotherapy through perturbation of Cas signaling pathways.

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Available from: Huy Q Ta, Mar 27, 2014
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    • "It has been recently reported that in breast tumors overexpression of both Her2 and p130Cas is associated with increased proliferation, metastasis and poor prognosis [10,11]. Moreover, high levels of p130Cas have also been associated with resistance to the cytotoxic agent doxorubicin [12] and to anti-estrogen receptor (ER) therapy [13,14]. "
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    ABSTRACT: Introduction Intrinsic plasticity of breast carcinoma cells allows them to undergo a transient and reversible conversion into mesenchymal cells to disseminate into distant organs, where they can re-differentiate to an epithelial-like status to form a cohesive secondary mass. The p130Cas scaffold protein is overexpressed in human ER+ and HER2+ breast cancer where it contributes to cancer progression, invasion and resistance to therapy. However, its role in regulating mesenchymal aggressive breast cancer cells remains to be determined. The aim of this study was to investigate the molecular and functional involvement of this adaptor protein in breast cancer cell plasticity. Methods We used silencing strategies and rescue experiments to evaluate phenotypic and biochemical changes from mesenchymal to epithelial traits in breast tumor cell lines. In the mouse A17 cell model previously related to mesenchymal cancer stem cells and basal-like breast cancer, we biochemically dissected the signaling pathways involved and performed functional in vivo tumor growth ability assays. The significance of the signaling platform was assessed in a human setting through the use of specific inhibitors in aggressive MDA-MB-231 subpopulation LM2-4175 cells. To evaluate the clinical relevance of the results, we analyzed publicly available microarray data from the Netherlands Cancer Institute and from the Koo Foundation Sun Yat-Sen Cancer Center. Results We show that p130Cas silencing induces loss of mesenchymal features, by downregulating Vimentin, Snail, Slug and Twist transcriptional factors, resulting in the acquirement of epithelial-like traits. Mechanistically, p130Cas controls Cyclooxygenase-2 transcriptional expression, which in turn contributes to p130Cas-dependent maintenance of mesenchymal phenotype. This cascade of events also compromises in vivo tumor growth through inhibition of cell signaling controlling cell cycle progression. c-Src and JNK kinases are sequential players in p130Cas/ Cyclooxygenase-2 axis and their pharmacological inhibition is sufficient to downregulate Cyclooxygenase-2 leading to an epithelial phenotype. Finally, in silico microarray data analysis indicates that p130Cas and Cyclooxygenase-2 concomitant overexpression predicts poor survival and high probability of breast tumor recurrence. Conclusions Overall, these data identify a new p130Cas/Cyclooxygenase-2 axis as a crucial element in the control of breast tumor plasticity, opening new therapeutic strategies leading to inhibition of these pathways in aggressive breast carcinoma.
    Full-text · Article · Oct 2012 · Breast cancer research: BCR
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    • "p130 Cas was shown to be associated with tamoxifen (Dorssers et al. 2001) and adriamycin (Ta et al. 2008) resistance in human breast carcinomas in vivo and in vitro, respectively. Expression of Src*/CasSD in TAM-R cells re-sensitized TAM-R cells to tamoxifen (Soni et al. 2009) and RNAi-mediated depletion of p130 Cas in breast cancer cells increased the efficiency of adriamycin treatment (Ta et al. 2008). Interestingly, expression of the Src*/CasSD in TAM- R cells attenuated signaling pathways which are also involved in p130 Cas -mediated adriamycin resistance, suggesting that the Src*/CasSD approach might increase the susceptibility to adriamycin as well. "

    Full-text · Chapter · Nov 2011
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    • "Intriguingly, we found that reduced levels of Cas offer protection against cell death induced by the DNA-damaging agent Doxorubicin, too, and this protection again coincides with induction of autophagy. Combined with the findings by Ta et al. noting that overexpression of Cas results in chemoresistance [5], our results suggest that Cas may have a universal yet complex regulatory role in cell death signaling in response to multiple different stimuli, perhaps determined by Cas gene/protein dosage. "
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    ABSTRACT: The focal adhesion protein p130Cas (Cas) activates multiple intracellular signaling pathways upon integrin or growth factor receptor ligation. Full-length Cas frequently promotes cell survival and migration, while its C-terminal fragment (Cas-CT) produced upon intracellular proteolysis is known to induce apoptosis in some circumstances. Here, we have studied the putative role of Cas in regulating cell survival and death pathways upon proteasome inhibition. We found that Cas-/- mouse embryonic fibroblasts (MEFs), as well as empty vector-transfected Cas-/- MEFs (Cas-/- (EV)) are significantly resistant to cell death induced by proteasome inhibitors, such as MG132 and Bortezomib. As expected, wild-type MEFs (WT) and Cas-/- MEFs reconstituted with full-length Cas (Cas-FL) were sensitive to MG132- and Bortezomib-induced apoptosis that involved activation of a caspase-cascade, including Caspase-8. Cas-CT generation was not required for MG132-induced cell death, since expression of cleavage-resistant Cas mutants effectively increased sensitivity of Cas-/- MEFs to MG132. At the present time, the domains in Cas and the downstream pathways that are required for mediating cell death induced by proteasome inhibitors remain unknown. Interestingly, however, MG132 or Bortezomib treatment resulted in activation of autophagy in cells that lacked Cas, but not in cells that expressed Cas. Furthermore, autophagy was found to play a protective role in Cas-deficient cells, as inhibition of autophagy either by chemical or genetic means enhanced MG132-induced apoptosis in Cas-/- (EV) cells, but not in Cas-FL cells. Lack of Cas also contributed to resistance to the DNA-damaging agent Doxorubicin, which coincided with Doxorubicin-induced autophagy in Cas-/- (EV) cells. Thus, Cas may have a regulatory role in cell death signaling in response to multiple different stimuli. The mechanisms by which Cas inhibits induction of autophagy and affects cell death pathways are currently being investigated. Our study demonstrates that Cas is required for apoptosis that is induced by proteasome inhibition, and potentially by other death stimuli. We additionally show that Cas may promote such apoptosis, at least partially, by inhibiting autophagy. This is the first demonstration of Cas being involved in the regulation of autophagy, adding to the previous findings by others linking focal adhesion components to the process of autophagy.
    Full-text · Article · Oct 2011 · BMC Biology
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