Background: Silibinin, an herbal polyphenolic flavonolignan, has antioxidant and anticancer properties. Objectives: This study aimed to evaluate some cellular and molecular effects of silibinin on the human ovarian cancer SKOV-3 cell line. Methods: MTT assay was used for cytotoxicity investigations of silibinin at 24, 48, and 72 h. Apoptosis and cell cycle were studied by flow cytometry. Effect of silibinin on mRNA expression of Bcl-2, cyclin E, and SKP2 was determined by QRT-PCR. Results: Silibinin administration in lower concentrations (12.5 and 25 µg/ml) did not lead to significant (p < 0.05) changes in cell viability and even slightly increased cell growth after 72 h. However, silibinin in higher concentrations (≥ 50µg/ml) inhibited SKOV-3 cell proliferation in a dose- and time-dependent manner. The mode of cell growth inhibition was by the apoptosis induction and G2/M cell cycle arrest. Silibinin caused down-regulation of the anti-apoptotic gene namely Bcl-2. Additionally, silibinin resulted in down-regulation of the major genes in the cell cycle, including cyclin E and SKP2. Conclusions: Overall, this study confirms the ability of silibinin to suppress ovarian cancer progression through the induction of apoptosis and inhibition of G2/M phase transition. Silibinin may provide a more efficient and safer herbal pharmaceutic for ovarian cancer treatment.
