Inhibitory effect of rapamycin on proliferation of H₂₂ hepatic cancer in mice

Objective: To explore rapamycin's inhibitory effect on proliferation of H₂₂ hepatic cancer in mice. Methods: In vitro study, H₂₂ hepatic cancer cell lines were cultured with rapamycin, CsA, FK506, and 5-FU, respectively, for 48 h. The different drugs' inhibitory effect on proliferation was determined through MTT. The influences of different agents on the H ₂₂ hepatic cancer cell cycle were observed by flow cytometry. The vascular endothelial growth factor (VEGF) concentration of the supernatant fluid of the cultured H₂₂ hepatic cancer cell was detected by ELISA. In vivo study: C57BL/6 to Balb/c mice allogenic skin transplant was established, and the H₂₂ hepatic cancer cell was implanted under skin. Rapamycin, CsA, FK506 and 5-FU were fed to the mice, respectively. The effect of different immunosuppressors on the survival of skin graft was observed while the proliferation of the transplant tumor was investigated. VEGF concentration of treated mice serum was examined by ELISA. The microvessel density of the transplanted tumor was observed through immunohistochemistry staining of CD34. Results: The proliferation of the H₂₂ hepatic cancer cells was inhibited by rapamycin at the concentration of 0.01-1 mg/L. When the H ₂₂ hepatic cancer cells were cultured with different dose of rapamycin, the VEGF concentration of the supernatant fluid decreased significantly (P<0.05). The number of S phase cells decreased significantly compared to that of other agents (P<0.05). When the mice in different groups were fed with 1.5 mg/ (kg·d) and 4.5 mg/(kg·d) rapamycin, the lengthened survival time of the skin grafts was similar to that in CsA and FK506 groups. But the tumor volume was smaller than that in CsA and FK506 groups (P<0.05). Compared to that in the control group, the VEGF concentration of mice serum decreased in rapamycin group (P<0.05), and the microvessel density of the transplant tumor was reduced greatly (P<0.05). Conclusion: Rapamycin, as an immunosuppressor, significantly resists immunologic rejection and inhibits the proliferation of H₂₂ hepatic cancer, thus having its advantage in treating malignant hepatic cancer with liver transplantation.