Modulation of redox signaling promotes apoptosis in epithelial ovarian cancer cells.

ABSTRACT: OBJECTIVE:Epithelial ovarian cancer (EOC) cells are known to be resistant to apoptosis through a mechanism that may involve alteration in their redox balance. NADPH oxidase is a major source of intracellular superoxide, which is converted to the less toxic product by superoxide dismutase (SOD). Superoxide contributes to hypoxia inducible factor (HIF)-1? stabilization. We sought to determine the effects of inhibiting the generation of intracellular reactive oxygen species (ROS) on apoptosis of EOC cells. METHODS:Diphenyleneiodonium (DPI), an irreversible ROS inhibitor, was used to inhibit the generation of ROS in EOC cell lines, SKOV-3 and MDAH-2774, followed by assessment of apoptosis, NADPH oxidase, SOD3 and HIF-1? expression. A combination of immunohistochemistry, immunoprecipitation/western blot, and real-time RT-PCR were utilized to evaluate the expression of these enzymes in EOC cells as well as normal ovarian tissue and ovarian cancer tissue specimens. RESULTS:DPI treatment significantly induced apoptosis in both EOC cell lines as evident by increased caspase-3 activity and TUNEL assay. Additionally, both EOC cell lines were found to express NADPH oxidase, HIF-1?, and SOD3, which were highly sensitive to DPI treatment. DPI treatment resulted in reduced NADPH oxidase, SOD3 and HIF-1? levels. Furthermore, ovarian cancer tissues were found to manifest higher NADPH oxidase levels as compared to normal ovarian tissues. CONCLUSIONS:These data suggest that lowering oxidative stress, possibly through the inhibition of NADPH oxidase, induces apoptosis in ovarian cancer cells and may serve as a potential target for cancer therapy.

SUBMITTER: Jiang Z 

PROVIDER: S-EPMC4237166 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature