Diazoxide protects L6 skeletal myoblasts from H2O2-induced apoptosis via the phosphatidylinositol-3 kinase/Akt pathway.

OBJECTIVES AND DESIGN: Transplanted cell survival might greatly improve the therapeutic efficacy of cell therapy. Diazoxide (DZ), a highly selective mitochondrial ATP-sensitive potassium channel opener, is known to suppress cell apoptosis and protect cells in oxidative stressed ischemic environment. We explored the mechanisms involved in DZ pre-treatment-induced anti-apoptotic effect on L6 skeletal myoblast (SKM).

MATERIALS AND METHODS: L6 SKMs were divided into control group, H2O2 group, DZ + H2O2 group and DZ + LY + H2O2 group. Treatments of 400 μmol/L H2O2 for 24 h alone, or after 200 μmol/L DZ pre-treatment for 30 min, or after DZ and 50 μmol/L LY294002 co-administration for 30 min were performed. The cell apoptosis rates were assessed by flow cytometric analysis. The changes of mitochondrial membrane potential were determined by JC-1 mitochondrial staining. The activation of phosphatidylinositol-3 kinase (PI3K)/Akt, caspase-9 and caspase-3 was detected by western blot.

RESULTS: Compared with the H2O2 group, DZ pre-treatment protected cells from H2O2-induced damage, increased Akt phosphorylation, prevented mitochondrial membrane depolarization as well as the activation of caspase-9 and caspase-3 and decreased the cell apoptosis rate. However, the DZ-induced cytoprotective and anti-apoptosis effects were partly inhibited by co-administration of a PI3K inhibitor, LY294002.

CONCLUSIONS: These data suggest that DZ pre-treatment contributes to protection of L6 SKMs against apoptosis at least partly by activating the PI3K/Akt pathway and subsequently inhibiting the mitochondrial-mediated caspase-dependent apoptotic signalling pathway.