ABSTRACT
Objective To investigate the radiosensitizing effect of tetrandrine in human esophageal carcinoma cells (TE1) in vitro and its related mechanisms. Methods The cell proliferation was assessed by MTT assay. Colony formation was used to analyze radiosensitivity enhancement by tetrandrine in TE1cells. Western blotting was preformed to measure the cyclin B1 protein levels. Results Tetrandrine inhibited cell growth in a concentration and time depedant manner. The inhibition of proliferation was observed when cells were treated by 1.0, 5.0 and 10. 0 μg/ml tetrandrine for 24 h after irradiation ( P ＜0. 05;F= 3.09, 10.43 and 24. 00, respectively). The inhibition was more significant when cell were treated by 0. 1, 1.0, 5.0 and 10. 0 μg/ml tetrandrine for 48 h than 24 hours after irradiation (F =4. 12,12. 77, 44. 28, and 48.53 respectively ,all P ＜ 0. 01 ). The D0, Dq and SF2 decreased with the increase of the tetrandrine concentration. The maximal sensitizing enhancement ratio was 1.60 with 0. 5 μg/ml tetrandrine. Tetrandrine upregulated the expression of cyclin B1 and removed G2 / M arrest . Conclusions Tetrandrine can enhance radiosensitivity of TE1 cells. This effect may be associated with the increase of cyclin B1 expression to remove G2/M arrest.