Effects of HS and HSP70 function inhibition on mitochondria and proliferation of triple-negative breast cancer cells

Breast cancer has a high morbidity and mortality rate worldwide. The overexpression of HSP70 (Heat Shock Protein 70) has associated with the occurrence, development, treatment, prognosis and drug resistance in breast cancer, and may become a new target for anti-tumor therapy. In this paper, triple-negative breast cancer cells MDA-MB-231 were used to investigate the effects of HS (Heat Shock) and HSP70 inhibitor VER-155008 treatments on mitochondrial morphology and membrane potential by laser scanning confocal microscopy. Meanwhile, the cell proliferation was studied by MTT method. We observed that mitochondrial networks were broken and the mitochondrial membrane potentials were decreased with the HSP70 function inhibition, and its pro-apoptotic effects can be alleviated when VER-155008 treatment was combined with HS. These results were the same as the effects of HS and HSP70 inhibitor on MCF-7, ER-positive breast cancer cells, we had reported. In addition, the proliferation of MDA-MB-231 and MCF-7 after different treatments indicated that HS treatment promoted proliferation in MCF-7, but not in MDA-MB-231.