Ovarian cancer is a common human malignancy of the female reproductive system. However, chemotherapy has been proven to have limited effectiveness in a majority of patients. Resibufogenin (RB) is a major active ingredient in cinobufacini, which has been used in the treatment of human malignancies as adjunct agents. This study was designed to examine the anti-cancer effect of RB and the underlying mechanisms in ovarian cancer. Our results showed that RB treatment resulted in cell death, cell cycle arrest, and apoptosis in ovarian cancer cells. The anti-growth and pro-apoptotic effects of RB were also validated in xenograft mice models. Proteomics analysis indicated that RB was able to alter the expressions of several genes, which were involved in the regulation of glycolysis. The suppression effect of RB in the glycolysis pathway of ovarian cancer cells was validated by decreased glucose consumption, lactate production, and extracellular acidification rate (ECAR). We proposed that PIM1 functioned as the key target that mediated the anti-cancer effect of RB against ovarian cancer cells. Our results have revealed that RB downregulated PIM1 in ovarian cancer cells and its downstream genes involved in glycolysis. Moreover, our results indicated that the anti-growth activities and suppressing effect of RB on glycolysis were enhanced significantly by PIM1 knockdown but was attenuated by ectopic PIM1 expression. This provided evidence to support the role of PIM1 in the anti-cancer activities of RB.
Keywords: Apoptosis; Glycolysis; Ovarian cancer; PIM1; Resibufogenin.