Protective effects of SS31 on t-BHP induced oxidative damage in 661W cells

The present study aimed to investigate the ability of SS31, a novel mitochondria-targeted peptide to protect against t-BHP-induced mitochondrial dysfunction and apoptosis in 661W cell lines. The 661W cells were treated with various concentrations of SS-31 and an MTT assay was used to determine cell viability. The expression of nitrotyrosine and 8-hydroxydeoxyguanosine (8-OHdG) was detected using immunofluorescent staining. Apoptosis were assessed using Hoechst staining and an annexin V/propidium iodide flow cytometer. Reactive oxygen species (ROS) were detected using MitoSOX(™) with confocal microscopy. Changes in mitochondrial membrane potential were analyzed using flow cytometry. In addition, the release of cytochrome c was analyzed using confocal microscopy. The viability of the cells improved following treatment with SS31 between 100 nM and 1 µM, compared with untreated control group. Compared with the t-BHP treatment group (20.0±3.8%), the number of annexin V-positive cells decreased dose-dependently to 13.6±2.6, 9.8±0.5 and 7.4±2.0% in the SS-31 treated group at concentrations of 10 nM, 100 nM and 1 µM, respectively. Treatment with SS-31 significantly prevented the t-BHP-induced expression of nitrotyrosine and 8-OHdG, decreased the quantity of mitochondrial ROS, increased mitochondrial potential, and prevented the release of cytochrome c from mitochondria into the cytoplasm. Therefore, the SS31 mitochondria-targeted peptide protected the 661W cells from the sustained oxidative stress induced by t-BHP.