Bilobetin induces apoptosis in human hepatocellular carcinoma cells via ROS level elevation and inhibition of CYP2J2

Bilobetin is a biflavonoid isolated from the leaves of Ginkgo biloba. Bilobetin displays several biological effects, however, the activities of bilobetin against cancer have been solely demonstrated. Thus, the aim of this study is investigating the apoptotic effects of and anticancer mechanism of bilobetin in Huh7 and HepG2 cells, both of human hepatocellular carcinoma (HCC) cell lines. MTT, cell counting, and colony formation assay showed that anti-proliferation effect of bilobetin. Cell cycle analysis revealed that bilobetin induces increase of population of the sub G1 phase. Annexin V/PI staining and TUNEL assay showed that bilobetin treatment promotes apoptotic cell death and DNA fragmentation. Bilobetin also induces ROS elevation and DNA damage in HCC cells. Western blot analysis elucidated that bilobetin displays apoptotic signaling pathway in HCC cells via upregulating cleaved PARP, cleaved caspase3 and Bax and downregulating CYP2J2. Bilobetin inhibited CYP2J2-catalyzed terfenadine and ebastine hydroxylase activities with IC₅₀ values of 0.81 and 2.21 μM, respectively. Transfection of CYP2J2 siRNA increased the anticancer effect of bilobetin in HCC cells through the inhibition of CYP2J2 expression. Taken together, this study suggests that bilobetin induces apoptosis against HCC cells via ROS level elevation and inhibition of CYP2J2.