Effect of PI3K-mediated autophagy in human osteosarcoma MG63 cells on sensitivity to the chemotherapy drug cisplatin

Objective: To investigate the influence of autophagy on sensitivity to the chemotherapy drug cisplatin (DDP) and the role of PI3K in autophagy. Methods: MTT methods and flow cytometer, with rapamycin up-regulating the autophagy and 3-MA down-regulating the autophagy, were employed to measure the proliferation inhibition rate on DDP-treated osteosarcoma cells and the change in cell cycle. The expression of intracellular protein was detected by Western blot. The autophagy of MG63 cell was observed using fluorescence microscope and transmission electron microscope. Results: Western blot showed that basic autophagy level of MG63 cell was significantly lower than that of hFOB cell. MTT test revealed that the cell proliferation inhibition rate in the group treated with rapamycin and DDP, group treated with 3-MA and DDP, and group only treated with DDP was significantly different. It was demonstrated by the flow cytometry that in group treated with DDP, inhibition on autophagy can increase the cell numbers in G(1) phase and reduce the cell numbers in S phase of cell cycle. Increase of autophagosome in MG63 cytoplasm was observed under fluorescence microscope. Conclusions: Up-regulating the autophagy significantly reduced the sensitivity of MG63 cell to chemotherapy with DDP. DDP induced autophagy of MG63 cell and blocked the cell cycle at G(1) phase.