Objective To explore the role of EGFR expression inhibition in enhancing the radiosensitivity of SKBR-3 cells by using siRNA. Methods EGFR-SiRNA and pNeg-SiRNA were transfected into SKBR-3 cells by lipofectamine. Western blot was used to measure the expression of EGFR. After 4Gy irradiation in a single fraction, cells were collected and apoptosis was estimated by flow cytometry at 0, 24 h and 48 hr, the DO, SF2 and a values of three cell lines were calculated by colone formation array. Results Two transfected cell lines were measured by Western blot and the result showed that the expression of EGFR was suppressed by the EGFR-siRNA. The apoptosis rates of SKBR-3/EGFR-siRNA were higher than those of control cells at 24hr and 48hr after irradiation (P<0.05). The DO and SF2 values of SKBR-3/EGFR-siRNA were 1.218 and 0.376 and the a value was 0.335. Conclusion Inhibition of EGFR by RNAi could enhance the radiosesitivity of SKBR-3 cells, so EGFR may be a good candidate target for cancer therapy.%目的 采用干扰RNA技术(small interfering RNA,siRNA)抑制SKBR-3,即HER-2(+++),EGFR(+++)乳腺癌细胞EGFR的表达,研究EGFR受抑制后HER-2过表达细胞对X线敏感性的变化.方法 质粒转染及鉴定:将细胞随机分为实验组、阴性对照组和空白组,重组质粒EGFR-siRNA和Neg-siRNA分别被转染入实验组及阴性对照组；Western blot检测各组细胞EGFR的表达水平；6MV射线照射4 Gy后0,24 h,48 h收集细胞,流式细胞术检测细胞凋亡率；克隆形成实验检测细胞D0,SF2和α等值.结果 质粒转染SKBR-3细胞,Western分析表明转染EGFR-siRNA的阳性细胞株在蛋白质水平受到明显抑制；X线照射24 h及48 h后,EGFR表达受抑制细胞凋亡率均高于转染阴性质粒组和空白对照组(P分别为0.045及0.039)；EGFR受抑制的细胞D0值和SF2值分别为1.218和0.376,α值为0.335.结论 运用RNAi技术可以有效抑制EGFR的表达从而提高SKBR-3细胞对X线的放射敏感性,EGFR是一个较理想的肿瘤分子治疗靶点.
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