肺腺癌细胞株表皮生长因子受体突变对射线诱导的DNA修复的影响

Effect of EGFR mutation on radiation-induced DNA repair in pulmonary adenocarcinoma cells

目的 探讨肺腺癌细胞株表皮生长因子受体（EGFR）酪氨酸激酶区域突变对放射线诱导的DNA双链断裂后修复的影响.方法 对A549细胞株（wt EGFR）和H1975细胞株（mutEGFR）进行6MVX射线照射.免疫荧光方法观察两种细胞株经4 GyX射线照射后不同时间点细胞核中γH2AX焦点数.免疫共沉淀法检测EGFR与DNA-PKcs的结合情况.Western blot方法检测细胞核中RAD51表达以及EGFR核转运情况.结果 H1975细胞株（mutEGFR）经X射线照射后DNA双链断裂修复延缓,EGFR不进行核转运,细胞核中无EGFR-DNA-PKcs复合物形成,且不影响细胞核RAD51的表达.A549细胞株（wt EGFR）经射线诱导后EGFR发生核转运,并与DNA-PKcs结合,发挥非同源修复,同时RAD51进入细胞核,发挥同源修复作用.结论 EGFR酪氨酸激酶区突变的肺腺癌细胞株能减少X射线诱导的DNA双链断裂后非同源修复和同源修复,延缓DNA修复动力学,从而增加放射敏感性.

Objective To observe the effect of EGFR mutation on radiation induced DNA repair in pulmonary adenocarcinoma ceils.Methods A549 cells with wild-type EGFR and H1975 cells with mutated-type of EGFR were irradiated by 4 Gy of 6 MV X-rays.After irradiation,the formation of nuclear γ-H2AX foci was assayed with immunostaining method,the level of DNA-PKcs-EGFR interaction was detected with coimmunoprecipitation,and nuclear RAD51 expression and EGFR nuclear translocation were detected using Western blot.Results DNA repair in the H1975 cells was significantly lower than that in A549 cells.In the irradiated H1975 cells,there was no EGFR translocation with further nuclear DNA-PKcs binding,and the expression of nucleus RAD51 was not altered.But in the irradiated A549 cells,EGFRDNA-PKcs interaction and nucleus RAD51 were increased.Conclusions Lung adenocarcinoma cell line with mutations in the tyrosine kinase domain （TKD） of EGFR exhibits a high radiosensitivity due to the reduction of the non-homologous end-joining （NHEJ） and homologous recombination （HR） DNA DSB repair kinetics.