Inactivated Sendai virus strain Tianjin induces apoptosis and autophagy through reactive oxygen species production in osteosarcoma MG-63 cells

Sendai virus strain Tianjin, a novel genotype of Sendai virus, has been proven to possess potent antitumor effect on certain cancer cell types although inactivated by ultraviolet (UV). This study was carried out to investigate the in vitro anticancer properties of UV-inactivated Sendai virus strain Tianjin (UV-Tianjin) on human osteosarcoma cells and the underlying molecular mechanism. Our studies demonstrated UV-Tianjin significantly inhibited the viability of human osteosarcoma cell lines and triggered apoptosis through activation of both extrinsic and intrinsic pathways in MG-63 cells. Meanwhile, autophagy occurred in UV-Tianjin-treated cells. Blockade of autophagy with 3-methyladenine remarkably attenuated the inhibition of cell proliferation by UV-Tianjin, suggesting that UV-Tianjin-induced autophagy may be contributing to cell death. Furthermore, UV-Tianjin induced reactive oxygen species (ROS) production, which was involved in the execution of MG-63 cell apoptosis and autophagy, as evidenced by the result that treatment of N-acetyl-L-cysteine, a ROS scavenger, attenuated both apoptosis and autophagy. In addition, inhibition of apoptosis promoted autophagy, whereas suppression of autophagy attenuated apoptosis. Our results suggest that UV-Tianjin triggers apoptosis and autophagic cell death via generation of the ROS in MG-63 cells, which might provide important insights into the effectiveness of novel strategies for osteosarcoma therapy.