Abstract: Objective To investigate the effects of bafilomycin A1(Baf) on the sensitivity of MCF-7 breast cancer cells to etoposide (VP-16). Methods The cultured cells were divided into normal control (NC), Baf , Vp-16 and VP-16 + Baf groups. The viability of cells was determined with MTT assay. After GFP-LC3 plasmid transfection to the cells, the distribution of green fluorescence was observed by using fluorescence microscopy. The protein expression was assayed by Western blot and the apoptosis of MCF-7 cells was detected by flow cytometry. Results VP-16 at 15μmol/L reduced the viability of cells. Baf (10nmol/L) which was added to treat the cells for 12h before the cells collection reduced the viability of cells more than VP-16 used only(P<0.01). VP-16 obviously induced the expression of LC3Ⅱ and GFP-LC3 dots in MCF-7 cells, and decreased the expression of p62. Baf inhibited the autophagy induced by VP-16, and increased the expression of cleaved-PARP in MCF-7 cells and the apoptotic rates (P<0.01). Conclusion VP-16 reduced the viability of breast cancer cells and induced protective autophagy, and inhibition of autophagy promoted the apoptotic death and increased the sensitivity of cells to VP-16.

Key words: etoposide, autophagy, Bafilomycin A1, apoptosis, breast cancer cell