中文摘要：

目的 探讨siRNA沉默Annexin A2基因表达对鼻咽癌CNE-2（R743）细胞放射敏感性的影响.方法 化学合成Annexin A2基因的siRNA经HiPerFect转染入R743细胞.RT-PCR和蛋白印迹法检测转染前后Annexin A2的mRNA和蛋白表达,克隆形成实验分析转染前后对细胞放射敏感性的影响,流式细胞仪和TUNEL实验分别检测转染前后经X线照射后细胞周期、细胞凋亡情况.结果 RT-PCR和蛋白印迹法结果显示转染组细胞Annexin A2基因及蛋白表达下调.克隆形成实验分析结果表明转染组Do、Dq、SF2值均低于单纯照射组和转染对照组,其相应放射增敏比（Do值比）分别为1.30和1.27.X线照射后转染组细胞G2＋M期比例增加并高于单纯照射组和转染对照组（32.46％、9.42％、9.17％,P=0.000、0.000）,转染组凋亡率也高于单纯照射组和转染对照组（35.20％、10.87％、11.33％,P=0.000、0.000）.结论 siRNA沉默Annexin A2基因表达可增强R743细胞放射敏感性,可能与DNA损伤修复、细胞周期时相分布变化有关.

英文摘要：

Objective To investigate the effect of silencing Annexin A2 gene expression by small interfering RNA （siRNA） on the radiosensitivity of nasopharyngeal carcinoma cells CNE-2 （R743）.Methods siRNA targeting the Annexin A2 gene was chemically synthesized and transfected into R743 cells by HiPerFect.The mRNA and protein levels of Annexin A2 before and after transfection were measured by RT-PCR and Western blot,respectively.The change in radiosensitivity of R743 cells was analyzed by colonyforming assay.Cell cycle distribution and apoptosis after X-ray irradiation were analyzed using flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling assay,respectively.Results The results from RT-PCR and Western blot showed that the expression of Annexin A2 was down-regulated after transfection.The colony-forming assay indicated that the D0,Dq,and SF2 in transfected cells were significantly lower than those in untransfected cells with radiation alone and in cells transfected with control siRNA.The sensitization enhancement ratios （D0 ratios） of transfected cells relative to untransfected and control siRNA transfected cells were 1.30 and 1.27,respectively.After X-ray irradiation,the proportion of cells in G2/M phase was significantly higher in the transfected cells thin in untransfected and control siRNA transfected cells （32.46% vs.9.17% and 9.42%,respectively;P =0.000 and 0.000）.The apoptosis rate was also significantly higher in the transfected cells than in the untransfected and control siRNA transfected cells （35.20% vs.10.87% and 11.33%,respectively;P=0.000 and 0.000）.Conclusions Silencing Annexin A2 gene expression by siRNA can increase the radiosensitivity of R743 cells,which may be associated with DNA damage repair and change in cell cycle distribution.