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Disruption of the interaction between PMCA2 and calcineurin triggers apoptosis and enhances paclitaxel-induced cytotoxicity in breast cancer cells
Baggott, Rhiannon R.; Mohamed, Tamer M.A.; Oceandy, Delvac; Holton, Marylouisa; Blanc, Marie C.; Roux-Soro, Sandrine C.; Brown, Sarah; Brown, James E; Cartwright, Elizabeth J.; Wang, Weiguang; Neyses, Ludwig and Armesilla, Angel L.
Disruption of the interaction between PMCA2 and calcineurin triggers apoptosis and enhances paclitaxel-induced cytotoxicity in breast cancer cells.
Cancer is caused by defects in the signalling mechanisms that govern cell proliferation and apoptosis. It is well known that calcium-dependent signalling pathways play a critical role in cell regulation. A tight control of calcium homeostasis by transporters and channel proteins is required to assure a proper functioning of the calcium-sensitive signal transduction pathways that regulate cell growth and apoptosis. The Plasma Membrane Calcium ATPase 2 (PMCA2) has been recently identified as a negative regulator of apoptosis that can play a significant role in cancer progression by conferring cells resistance to apoptosis. We have previously reported an inhibitory interaction between PMCA2 and the calcium-activated signalling molecule calcineurin in breast cancer cells. Here we demonstrate that disruption of the PMCA2/calcineurin interaction in a variety of human breast cancer cells results in activation of the calcineurin/NFAT pathway, up-regulation in the expression of the pro-apoptotic protein Fas Ligand, and in a concomitant loss of cell viability. Reduction in cell viability is the consequence of an increase in cell apoptosis. Impairment of the PMCA2/calcineurin interaction enhances paclitaxel-mediated cytotoxicity of breast tumoral cells. Our results suggest that therapeutic modulation of the PMCA2/calcineurin interaction might have important clinical applications to improve current treatments for breast cancer patients.