siRNA抑制Ku80表达后对宫颈癌HeLa细胞增殖的影响

Effect of Ku80 Expression Inhibition by RNA Interference on Proliferation of Cervical Carcinoma Cell Line HeLa

背景与目的:Ku80为细胞受辐射后DNA双链断裂(DNA doublestrand break,DSB)的主要修复蛋白。现阶段关于Ku80的研究主要集中在DSB修复方面,其他方面研究较少。本研究建立利用siRNA抑制Ku80表达的宫颈癌HeLa细胞模型,以此探讨Ku80在细胞增殖方面的作用。方法:构建靶向抑制Ku80的siRNA表达载体,转染HeLa细胞,筛选稳定表达siRNA的转化克隆;Western blot检测Ku80表达变化;克隆形成实验、MTT法和裸鼠皮下瘤形成实验分别检测细胞克隆形成率及细胞在体外和体内的增殖情况。结果:构建表达质粒pKu80-siRNA与pNeg-siRNA转染HeLa细胞,G418筛选后获得稳定转染克隆,Western blot分析表明转染pKu80-siRNA后的细胞Ku80蛋白表达受到明显抑制,将其命名为HeLa/Ku80-siRNA;转染pNeg-siRNA的HeLa细胞克隆形成率为0.62±0.02,而HeLa/Ku80-siRNA细胞的克隆形成率为0.46±0.05,明显低于对照细胞(t=5.11,P<0.01);MTT显示细胞培养48h和72h时,HeLa/Ku80-siRNA细胞的增殖率均显著低于对照细胞(P<0.05);裸鼠皮下瘤生长实验示种植25天时,HeLa/Ku80-siRNA细胞种植瘤的平均体积为(18.92±3.60)mm3,明显低于对照细胞种植瘤体积(194.88±30.61)mm3,(t=12.69,P<0.01)。结论:稳定转染及siRNA技术建立的Ku80表达抑制克隆可以成为简单实用的细胞模型;Ku80-siRNA抑制Ku80的表达后可以在体内外抑制HeLa细胞的增殖。

BACKGROUND ＆ OBJECTIVE： Ku80 is a key protein plays a role in repairing DNA double strand break （DSB） after irradiation. There are a few studies about other roles of Ku80 except DSB repair. This study was to inhibit Ku80 expression in cervical carcinoma cell line HeLa with small interfering RNA （siRNA）, and explore its effect on cell proliferation, METHODS： Plasmids pKu80-siRNA and pNeg-siRNA （negative control） were constructed and transfected into HeLa cells. The expression of Ku80 in HeLa cells was detected by Western blot. The proliferation of HeLa cells in vitro and in vivo was determined by clone formation assay, MTT assay, and subcutaneous tumor formation in nude mice. RESULTS.. Two cell clones were screened from pKu80-siRNA- and pNeg-siRNA-transfected HeLa cells. Ku80 expression in HeLa cells was suppressed markedly after transfection of pKu80-siRNA; this clone was named Hela/Ku80-siRNA. The clone formation efficiency was significantly lower in HeLa/Ku80-siRNA cells than in control cells （0.46±0.05 vs. 0.62±0.02, t=5.11, P〈0.01）. The proliferation rate was significantly lower in HeLa/Ku80-siRNA cells than in control cells at 48 h and 72 h after transfection （P〈0.05）. At the 25th day after subcutaneous transplantation in nude mice, the tumor volume was significantly smaller in HeLa/Ku80-siRNA group than in control group [（18.92 ±3.60） mm^3 vs. （194.88±30.61） mm^3, t=12.69, P〈0.01]. CONCLUSIONS： We successfully established a cell model that Ku80 expression is suppressed almost completely by siRNA. Ku80 inhibition inhibits the proliferation of HeLa cells in vivo and in vitro.