Isoalantolactone induces autophagic cell death in SKOV3 human ovarian carcinoma cells via upregulation of PEA-15

We investigated the effects of isoalantolactone on cell growth inhibition and underlying cell death mechanisms in SKOV3 human ovarian cancer cells. The effects of isoalantolactone on cell proliferation and cell cycle were examined by EdU incorporation assay and DNA content assay. Western blotting was performed to determine the protein expression effects of isoalantolactone on cell cycle-related proteins, autophagic regulators and PEA-15. Autophagic vacuoles were observed by acridine orange staining. PEA-15 knockdown by siRNA was used to confirm that PEA-15 was involved in isoalantolactone-induced autophagy of SKOV, cells. Isoalantolactone inhibited the viability and proliferation of SKOV, cells in a dose- and time-dependent fashion. Isoalantolactone induced cell cycle arrest at G2/M phase and decreased the expression of cell cycle-related proteins cyclin B1 and CDK1 in SKOV, cells. Accordingly, isoalantolactone also induced SKOV, cell autophagy via accumulation of autophagic vacuoles in the cytoplasm, increased Beclinl protein expression, and increased LC3 cleavage. Furthermore, we observed that isoalantolactone-induced autophagy was through increased PEA-15 expression and the phosphorylation of ERK, whereas less change was observed to autophagy on SKOV, cells through PEA-15 knockdown by siRNA. Isoalantolactone-induced autophagic cell death was further confirmed by pretreatment with the autophagy inhibitor 3-methyladenine (3-MA). In conclusion, isoalantolactone induced cell cycle arrest and autophagy and inhibited cell proliferation of SKOV, cells via the upregulated PEA-15 expression and the phosphorylation of ERK.