Inhibition of growth and metastasis of hepatocellular carcinoma by rapamycin: experiment with mice

Abstract

To investigate the effects of rapamycin (RPM) in inhibiting the growth and metastasis of hepatocellular carcinoma (HCC). Human HCC cells of the line MHCC97H with a high potential of metastasis were divided into 3 groups to be cultured with cyclosporine A (CsA) 100 ng/ml, RPM 10 ng/ml, or CsA + RPM for 48 hours. Flow cytometry was used to examine the apoptosis and cell cycle MTT method was used to examine the effect of RMP on the proliferation of the MHCC97H cells. RT-PCR was used to detect the mRNA expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), hypoxia-inducible factor-1alpha (HIF-1alpha), and transforming growth factor b (TGFb). Another MHCC97H cells were cultured in complete medium without RPM for 48 hours, then the protein expression of VEGF in the supernatant was detected by ELISA. Twenty-eight nude LCI-D20 mice were inoculated with human HCC cells and then divided into 4 groups to be fed with CsA (25 mg/kg), RPM (2 mg/kg), CsA + RPM, and normal saline (0.2 ml, as control group) for 35 days. Then the mice were killed to take the weight of inoculated tumor, measure the blood drug concentration, calculate the lung metastasis rate and number of metastatic foci, and observe pathology of the lung. CsA showed no effect on the cycle of the MHCC97H cells. The MHCC97H cells of the RPM and CsA + RPM groups arrested at the stage G(0)/G(1) (both P = 0.000). MMT method also showed that the proliferation of the MHCC97H cells in the RPM and CsA + RPM groups were blocked (P = 0.003 and P = 0.002). However, CsA did not influence the proliferation of the MHCC97H cells. Flow cytometry showed that RPM did not promote the apoptosis of the MHCC97H cells. RT-PCR showed that RPM down-regulated the mRNA expression of VEGF and HIF-1alpha (both P < 0.05), however, did not influence the mRNA expression of bFGF, TGFb, and TGFb. The VEGF protein level in the supernatant of the culture fluid of MHCC97H cells of the RPM group was (890.3 +/- 25.1) pg/ml, significantly lower than that of the control group, (1583.7 +/- 17.3) pg/ml (P = 0.000). The tumor inhibiting rate of the RPM group was 63.7%, not significantly different from that of the RPM + CsA group (80.9%, P = 1.000). The metastatic rate of the CsA and control groups were both 100% with a higher number of metastatic tumors in the CsA group (P = 0.046). RPM significantly inhibits the growth and metastasis of HCC. RPM-based immunosuppressive regimen may be of value in HCC patients receiving liver transplantation.