Inhibitory effects of nobiletin on hepatocellular carcinoma in vitro and in vivo.

Nobiletin (5, 6, 7, 8, 3' 4'-hexamethoxyflavone) is a major anticancer component in juice from zhishi (Rutaceae). This study aimed to investigate the inhibitory effect of Nobiletin on hepatic cancer cells both in vitro and in vivo. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), growth curve, and clonogenic assay showed that nobiletin inhibited the proliferation of SMMC-7721 cells in vitro. Hoechst staining observed the characteristics of cell apoptosis in nobiletin-treated cells, and the apoptotic rates of treated groups were increased in a dose-dependent manner. Flow cytometric analysis demonstrated that nobiletin could block the cell cycle arrested at G2 phase. Cell cycle analysis was performed using flow cytometry. Results showed that cell cycle phase distribution analysis showed G2 arrest. It was found that nobiletin downregulated the expressions of Bcl-2 and COX-2 and up-regulated the expressions of Bax and caspase-3 in SMMC-7721 cells by western blotting. The experiment in vivo demonstrated that nobiletin significantly inhibited the growth of H22 transplantable tumor, downregulated the expressions of COX-2, up-regulated the expressions of Bax and caspase-3 detected by immunohistochemistry and western blotting, and the ratios of Bcl-2/Bax were decreased. Our results suggest that nobiletin has significant inhibitory effects on hepatocellular carcinoma both in vitro and in vivo.