Effects and mechanisms of silibinin on human hepatocellular carcinoma xenografts in nude mice

Abstract

To investigate the in vivo effects and mechanisms of silibinin on the growth of hepatocellular carcinoma (HCC) xenografts in nude mice. Nude mice bearing HuH7 xenografts were used to assess the anti-HCC effects and mechanisms of silibinin. Silibinin resulted in a potent dose-dependent reduction of HuH7 xenografts in association with a significant decrease in Ki-67 and alpha-fetoprotein production, nuclear NF-kappaB content, polo-like kinase 1, Rb phosphorylation, and E2F1/DP1 complex, but increased p27/CDK4 complex and checkpoint kinase 1 expression, suggesting that the in vivo effects of silibinin are mediated by inhibiting G1-S transition of the cell cycle. Silibinin-induced apoptosis of HuH7 xenografts was associated with inhibited survivin phosphorylation. Silibinin-reduced growth of HuH7 xenografts was associated with decreased p-ERK, increased PTEN expression and the activity of silibinin was correlated with decreased p-Akt production, indicating involvement of PTEN/PI(3)K/Akt and ERK pathways in its in vivo anti-HCC effects. Silibinin-reduced growth of HuH7 xenografts was also associated with a significant increase in AC-H3 and AC-H4 expression and the production of superoxide dismutase (SOD)-1. Silibinin reduces HCC xenograft growth through the inhibition of cell proliferation, cell cycle progression and PTEN/P-Akt and ERK signaling, inducing cell apoptosis, and increasing histone acetylation and SOD-1 expression.