LRIG1对人脑胶质瘤放疗敏感性的作用及其机制

目的 探讨多亮氨酸重复区免疫球蛋白样蛋白1( LRIG1)对人脑胶质瘤细胞株U251放疗敏感性的影响及其机制.方法 应用脂质体介导的基因转染技术将PEGFP-N1、PEGFP-LRIG1 质粒分别转染人人脑胶质瘤U251细胞,G418( 1000 mg/L)筛选,建立稳定细胞株,采用克隆形成实验测定N1-U251及LRIG1-U251两组细胞的放射敏感性,Western blot法测定两组细胞中LRIG1及RAD51蛋白的表达差异,彗星分析法测定两组细胞双链DNA断裂的修复.结果 成功建立高表达LRIG1的U251稳定细胞株,LRIG1-U251组(0.352±0.011)较N1-U251组(0.071±0.003) LRIG1基因表达明显上调(P＜0.01).LRIG1基因表达上调后U251细胞的放射敏感性增加,放射增敏比为1.448.上调LRIG1基因明显抑制了RAD51基因的表达(P＜0.01)及照射后的高表达(P＜0.01).彗星分析表明LRIG1基因的过表达将照射8h后U251细胞的Olive彗尾力矩由21.14±3.42增加至32.81±5.61 (P ＜0.05).结论 LRIG1可以增加人脑胶质瘤U251细胞的放射敏感性.机制可能是通过降低RAD51蛋白表达,进而抑制双链DNA损伤的修复.

Effects of LRIG1 expression on radiosensitivity of human glioma cells and the possible mechanism

Objective To investigate the effect of the expression of leucine-rich repeats and immunoglobulin-like domains 1 ( LRJG1 ) on the radiosensitivity of human glioma cell line U251 cells and the possible mechanism.Methods The PEGFP-N1,PEGFP-LRIG1 plasmids were transfected into U251 cells with application of liposome-mediated gene transfer technology.And the cells stably transfected were selected by G418.The radiosensitivity of N1-U251 and LRIG1-U251 cells was analyzed by clonogenic assay.Western blotting demonstrated the expression of LRIG1 and RAD51.Repairment of double-strand (ds) DNA breaks was measured by comet assay.Results The LRIG1 protein level in LRIG1-U251 group (0.352 ± 0.011 ) was significantly up-regulated compared to N1-U251 group ( 0.071 ± 0.003 ) ( P ＜0.01 ).Overexpression of LRIG1 up-regulated the radiosensitivity of U251 cells with the sensitive enhancement ratio (SER) being 1.448.The RAD51 protein levels were significantly suppressed before (P＜0.01 ) and after irradiation ( P ＜0.01 ) by up-regulating the LRIG1 expression.Comet assay demonstrated the overexpression of LRIG1 increased the Olive Tail Moment of U251 cells from 21.14 ±3.42 to 32.81 ±5.61 after 8-h radiation ( P ＜ 0.05 ).Conclusion Up-regulation of the LRIG1 expression can down-regulate the RAD51 expression,and then inhibit the repairment of dsDNA breaks,increase the radiosensitivity of U251 cells.