Effects of rapamycin on osteosarcoma cell proliferation and apoptosis by inducing autophagy.

OBJECTIVE: To investigate the influences of rapamycin on proliferation and apoptosis of human osteosarcoma MG-63 cells and the mechanisms of action. MATERIALS AND METHODS: The human osteosarcoma MG-63 cells were randomly divided into Control group, Rapamycin group, and Rapamycin + Beclin-1 plasmid transfection group. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was adopted to detect the viability of MG-63 cells in each group, and the 5-Ethynyl-2'-deoxyuridine (EdU) staining and Hoechst staining were applied to determine the proliferation and apoptosis, respectively, of MG-63 cells in each group. The levels of B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) were measured using enzyme-linked immunosorbent assay (ELISA) kits, and the protein expression levels of Beclin-1 and Vps34 in each group of MG-63 cells were tested using the Western blotting. RESULTS: Compared with the Control group, Rapamycin group, and Rapamycin + Beclin-1 plasmid transfection group had markedly weakened the viability of MG-63 cells, inhibited cell proliferation, remarkably increased cell apoptosis rate, elevated Bax level, notably declined Bcl-2 level, and significantly raised the levels of Beclin-1 and Vps34 proteins in MG-63 cells. Besides, the effects in Beclin-1 plasmid transfection group were stronger. CONCLUSIONS: Rapamycin may decrease the viability, inhibit the proliferation, and promote the apoptosis of MG-63 cells by activating autophagy.