To investigate the effect of simvastatin on cell cycle related proteins Cyclin D1, Cyclin E, CDK4 and pRB in cholangiocarcinoma.

In vitro, after 24 and 48 h of treatment with simvastatin, the proliferation of cholangiocarcinoma cells EGI-1 was detected by cell counting kit-8 (CCK-8). Then qPCR were employed to determine the expressions of cell cycle-related genes Cyclin D1, Cyclin E, CDK 4 and pRB. And related proteins were further analyzed by Western blotting according to the result of qPCR . In vivo, twelve NOD-SCID mice were inoculated with EGI-1cell, then they were randomly divided into experimental group and control group after tumor formation, with 6 rats in each group. The experimental group took 20 mg/kg simvastatin every day, while the control group took simvastatin solvent every day. Simvastatin were given at a dose of 20 mg/kg once a day for the experimental group, while the solvent were given for the control group. 24 days later, the volume of tumors were measured and immunohistochemical staining was performed to determine the expression level of the above proteins in vivo.

The proliferation of EGI-1 cell was suppressed by simvastatin in a dose-dependent manner. The half maximal inhibitory concentration of 24 and 48 h were (8.27±0.77) μmol/Land (5.90±1.81) μmol/L, respectively. Simvastatin significantly suppressed mRNA expressions of Cyclin D1, CDK4 and pRB after 48 h ( P<0.05). No significant difference was found in mRNA expression of Cyclin E. Correspondingly, proteins of Cyclin D1, CDK4 and pRB were downregulated, which were consistent with the results of mRNA. And increasing simvastatin treated time could elevated this suppression. Simvastatin treatment yielded a significant growth inhibition in vivo. Immunohistochemical staining illustrated that Cyclin D1, CDK4 and pRB expressions were markedly downregulated by simvastatin in transplanted tumor (P<0.05).

Simvastatin inhibits cholangiocarcinoma cell by down-regulating cyclins such as Cyclin D1, CDK4, pRB.