Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) as an O₂{radical dot}^- generator induces apoptosis via the depletion of intracellular GSH contents in Calu-6 cells

Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) is an uncoupler of mitochondrial oxidative phosphorylation in eukaryotic cells. Here, we investigated an involvement of O₂{radical dot}^- and GSH in FCCP-induced Calu-6 cell death and examined whether ROS scavengers rescue cells from FCCP-induced cell death. Levels of intracellular O₂{radical dot}^- were markedly increased depending on the concentrations (5-100 μM) of FCCP. A depletion of intracellular GSH content was also observed after exposing cells to FCCP. Stable SOD mimetics, Tempol and Tiron did not change the levels of intracellular O₂{radical dot}^-, apoptosis and the loss of mitochondrial membrane potential (ΔΨ_m). Treatment with thiol antioxidants, NAC and DTT, showed the recovery of GSH depletion and the reduction of O₂{radical dot}^- levels in FCCP-treated cells, which were accompanied by the inhibition of apoptosis. In contrast, BSO, a well-known inhibitor of GSH synthesis, aggravated GSH depletion, oxidative stress of O₂{radical dot}^- and cell death in FCCP-treated cells. Taken together, our data suggested that FCCP as an O₂{radical dot}^- generator, induces apoptosis via the depletion of intracellular GSH contents in Calu-6 cells.