Effect of BMI-1 on radiosensitization of esophageal carcino-ma cells after silencing of BMI-1 gene / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the effects of BMI-1 expression inhibition by RNA interference on the radiosensitivity of esophageal cancer TE-13 cells and its mechanism.Methods The siRNA based on the sequence of BMI-1 mRNA was synthesized to transfect cultured TE-13 cells as BMI-1 siRNA group,a negative one was synthesized to transfect cultured TE-13 cells as negative control group (NC group),and untransfected TE-13 cells were named as control group.The expression of the BMI-1 mRNA and protein in TE-13 cells was measured by quantitative real-time PCR and Western blot,respectively.The cell proliferation and the radiosensitivity of TE-13 cells were measured by MTS and colony-forming assay,respectively.Flow cytometry was used to analyze cell cycle and apoptosis.The expression of BCL-2 and BAX in TE-13 cells was measured by Western blot.Comparison between groups was made by analysis of variance.Results The BMI-1 siRNA group had significantly lower expression of BMI-1 mRNA and protein than the control group and the NC group (P=0.000,0.000).The proliferation of TE-13 cells in the BMI-1 siRNA group decreased significantly after irradiation (P=0.031).The colony-forming assay showed that the BMI-1 siRNA group had a significantly higher radiosensitivity than the control group and the NC group (P=0.000).After irradiation,the BMI-1 siRNA group had a significantly lower percentage of cells in G2/M phase than the control group and the NC group (P=0.000,0.000).The BMI-1 siRNA group had a significantly increased apoptosis rate (P=0.000,0.000),significantly reduced expression of BCL-2(P=0.000,0.000),and significantly increased expression of BAX after irradiation (P=0.000,0.000).Conclusions BMI-1 siRNA can inhibit the expression of BMI-1 gene in esophageal cancer TE-13 cells,eliminate the cell cycle arrest in G2/M phase,induce cell apoptosis after ionizing irradiation in vitro,and increase the radiosensitivity,which may be related to the regulation of the expression of BCL-2 and BAX.