Pomolic acid induces apoptosis in SK-OV-3 human ovarian adenocarcinoma cells through the mitochondrial-mediated intrinsic and death receptor-induced extrinsic pathways

The cytotoxic effect of pomolic acid (PA), a penta-cyclic triterpene isolated from flowers of Osmanthus fragrans var. aurantiacus Makino, was investigated in SK-OV-3 human ovarian adenocarcinoma cells. PA dose-dependently inhibited the viability of SK-OV-3 cells. PA-induced apoptosis was further characterized by detection of cell surface annexin V and sub-G1 apoptotic cell populations. The number of cells immunostained with annexin V-fluorescein isothiocyanate (FITC) increased following treatment with PA. The sub-G1 cell populations also increased in PA-treated SK-OV-3 cells. PA induced the activation of caspase-8, -9 and -3; critical mediators of apoptosis signaling. PA decreased the mitochondrial transmembrane potential (Delta Psi(m)), resulting in the activation of caspase-9. In addition, PA increased the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis signaling-related death receptor 5 (DR5), mediating caspase-8-involved extrinsic pathway. Taken together, our results indicate that PA induces apoptosis in SK-OV-3 cells, which is mediated by the mitochondrial-mediated intrinsic and death receptor-induced extrinsic pathways.