An ROS generator, antimycin A, inhibits the growth of HeLa cells via apoptosis

Anti mycin A (AMA), an inhibitor of electron transport in mitochondria, has been used as a reactive oxygen species (ROS) generator in biological systems. Here, we investigated the in vitro effect of AMA on apoptosis in He Lace I Is. AMA inhibited the growth of HeLa cells with an IC50 of about 50 mu M. AMA efficiently induced apoptosis, as evidenced by flow cytometric detection of sub-G DNA content, annexin V binding assay, and DAPI staining. This apoptotic process was accompanied by the loss of mitochondrial membrane potential (Delta Psi(m)), Bcl-2 down-regulation, Bax up-regulation, and PARP degradation. All caspase inhibitors used in this experiment, especially pan-caspase inhibitor (Z-VAD), could rescue some HeLa cells from AMA-induced cell death. When we examined the changes of the ROS, H2O2 or O-2(,)- , in AMA-treated cells, H2O2 and O-2- were markedly increased. In addition, we detected the depletion of GSH content in AMA-treated cells. Pan-caspase inhibitor showing the efficient anti-apoptotic effect significantly reduced GSH depletion by AMA. Superoxide dismutase (SOD) and catalase did not reduce intracellular ROS, but these could strongly rescue the cells from apoptosis. However, these anti-apoptotic effects were not accompanied by the recovery of GSH depletion. Interestingly, catalase significantly decreased the CMF negative (GSH depletion) and propidium iodide (PI) positive cells, indicating that catalase strongly maintained the integrity of the cell membrane in CMF negative cells. Taken together, these results demonstrate that AMA potently generates ROS, induces the depletion of GSH content in HeLa cells, and strongly inhibits the growth of HeLa cells throughout apoptosis. J. Cell. Biochem. 102: 98-109, 2007. (C) 2007 Wiley-Liss, Inc.