Avoidance of apoptosis is a hallmark of cancer; hence there is a great interest in developing therapies that reactivate cell death. The pro-survival protein MCL-1 is over-expressed in cancer and confers resistance to therapy, however the mechanism by which MCL-1 regulates cell survival is not fully understood.
We aim to investigate the mechanisms underlying MCL-1 dependent survival and chemo-resistance in breast cancer via proteomic methods. To expand our approach we will be using a specific MCL-1 ligand, BIMs2A, to determine if MCL-1 antagonism is able to prime breast cancer cells for death.
Preliminary data from our laboratory has demonstrated that forced expression of the MCL-1 antagonist BIMs2A in MDA-MB-468 triple negative breast cancer (TNBC) cells resulted in increased cell death and cytotoxic sensitivity to ABT-737 and irradiation. This demonstrates that MCL-1 plays a role in breast cancer cell survival.
The mechanisms of MCL-1 are most likely due to its protein-protein interactions, not only with the other known members of the BCL-2 family, but also unknown interacting partners. We hope to identify novel binding partners of MCL-1 under normal and antagonised conditions using immunoprecipitation of MCL-1 and its binding partners prior to LC-MS/MS analysis in the TBNC cell lines MDA-MB-468 and MDA-MB-231. We will couple this with analysis of downstream signalling pathways investigating changes in protein phosphorylation status and protein expression using appropriate techniques.
With these data and techniques we hope to demonstrate the mechanism by which MCL-1 regulates cytotoxic resistance of MCL-1 expressing TNBC cell lines. Thus targeting MCL-1 activity may provide a novel therapeutic target for advanced breast cancer.