Mitochondrial complex I inhibitor rotenone induces apoptosis through enhancing mitochondrial reactive oxygen species production

Inhibition of mitochondrial respiratory chain complex I by rotenone had been found to induce cell death in a variety of cells. However, the mechanism is still elusive. Because Reactive Oxygen Species (ROS) play an important role in Apoptosis and inhibition of mitochondrial respiratory chain complex I by rotenone was thought to be able to elevate mitochondrial ROS production, we investigated the relationship between rotenone-induced Apoptosis and mitochondrial Reactive Oxygen Species. Rotenone was able to induce mitochondrial complex I substrate-supported mitochondrial ROS production both in isolated mitochondria from HL-60 cells as well as in cultured cells. Rotenone-induced Apoptosis was confirmed by DNA fragmentation, cytochrome c release, and Caspase 3 activity. A quantitative correlation between rotenone-induced Apoptosis and rotenone-induced mitochondrial ROS production was identified. Rotenone-induced Apoptosis was inhibited by treatment with antioxidants (glutathione, N-acetylcysteine, and vitamin C). The role of rotenone-induced mitochondrial ROS in Apoptosis was also confirmed by the finding that HT1080 cells overexpressing magnesium superoxide dismutase were more resistant to rotenone-induced Apoptosis than control cells. These results suggest that rotenone is able to induce Apoptosis via enhancing the amount of mitochondrial Reactive Oxygen Species production.