Hepatocellular carcinoma (HCC) is one of major health concerns worldwide and one of leading causes of cancer death after lung and gastric cancers. Simvastatin is a cholesterol-lowering drug which inhibits 3-hydroxy-3-methylglutarylcoenzyme CoA (HMG-CoA) reductase. Simvastatin exhibits numerous pleiotropic effects including anti-cancer activity. Yet, the anticancer effects in HCC remain poorly characterized. Therefore, in this study, we investigated the effects of simvastatin on tumor cell growth, apoptosis and cell cycle. HepG2 and Huh7 cell lines were treated with simvastatin (32 and 64 µM) for different time periods. Tumor cell growth was assessed using MTT assay. Apoptosis and cell cycle analysis were also evaluated. Analysis of cell cycle proteins involved in simvastatin-induced manipulation was performed by Western blot and quantitative RT-PCR analyses. Simvastatin induced a reduction of tumor cell growth. In both cell lines, simvastatin induced apoptosis and impaired cell cycle progression as depicted by the greater rates of G0/G1-phase cells than the rates of S-phase cells. Protein expression levels of cell cycle regulating proteins CDK1, CDK2, CDK4, cyclin D1, cyclin E, p19 and p27 were markedly altered by simvastatin. Moreover, CDC2, CCND1 and CDCN2D mRNA expressions were also altered by drug treatment. Collectively, these results suggest that simvastatin induces apoptosis in tumor cells and its anti-proliferative activity was accompanied by inhibition of cyclin-dependent kinases and cyclins, whereas CDK inhibitors p19 and p27 were enhanced. These results may provide novel insights into simvastatin tumor-suppressive action.

Abstract. Hepatocellular carcinoma (HCC) has become a global health concern and is one of the leading causes of cancer death after lung and gastric cancers. It has been suggested that the 3-hydroxy-3-methyl-glutarylcoenzymeCoA (HMG-CoA) reductase inhibitor simvastatin exhibits anticancer properties. To this end, we analyzed the influence of simvastatin on the cell growth and adhesion of HCC and evaluated the yet poorly characterized mechanism of action of simvastatin in HCC. HepG2 and Huh7 cells were treated with simvastatin (16-64 μM) for different time periods. Cell proliferation using the MTT assay and tumor cell adhesion to endothelial cell monolayers were evaluated. ß1, ß3 and ·2 integrin adhesion receptors and the downstream target of simvastatin Rho-dependent kinase (ROCK) were analyzed by Western blot. Further blocking studies with the ROCKinhibitor H1152 and anti-integrin ß1 and ß3 antibodies were carried out. Simvastatin treatment inhibited dose-dependently tumor cell growth and attachment to endothelium. The inhibitory effect of simvastatin on cell adhesion was associated with decreased expression of ß1, ß3 and ·2 integrins. Furthermore, simvastatin strongly reduced the expression of ROCK-I and activated MYPT, an indicator of ROCK activity. Also, the ROCK-inhibitor H1152 reduced the adhesive capacity of the tumor cells. Anti-adhesive effects of simvastatin were prevented by exogenous mevalonate, a downstream product of HMG-CoA. Tumor cell adhesion to endothelium was significantly impaired following incubation with functional anti-ß1 antibody. Simvastatin modifies the expression of cell adhesion molecules leading to reduced tumor cell growth and invasion. These beneficial effects of simvastatin may be mediated by ROCK. The data presented may point to novel treatment options for HCC.