中文摘要：

目的：探讨shRNA介导的XRCC2基因沉默联合辐射对结肠癌细胞移植裸鼠肿瘤的疗效。方法将结肠癌T84细胞接种于BALB/c裸鼠建立肿瘤移植模型，分为control组、shRNA？SC组和shRNA？XRCC2组。裸鼠经X射线局部照射，检测放射治疗后肿瘤的体积和质量变化，并对肿瘤组织进行病理分析。结果 shRNA？XRCC2组肿瘤生长速度较缓慢，从放射治疗的第12天开始至放射治疗继续到第28天，shRNA？XRCC2组瘤体明显较control组减小，差异有统计学意义（P〈0.01）。shRNA？XRCC2组肿瘤质量明显轻于control组，二者比较差异有统计学意义（t=18.843，P〈0.01）。shRNA？XRCC2组裸鼠移植瘤的抑瘤率为56.25%，远远高于shRNA？SC组（4.69%）。移植瘤组织的病理检查结果表明，shRNA？XRCC2组肿瘤组织核异型不明显，少见核分裂相，多见坏死区。结论 XRCC2基因沉默联合辐射对裸鼠结肠癌移植瘤具有显著的抑瘤效果。

英文摘要：

Objective To study the curative effect of XRCC2 gene silencing mediated by shRNA combined with radiation on human colonic trans-planted carcinoma in nude mice. Methods Colonic carcinoma T84 cells were transfered into BALB/c nude mice to establish a tumor xenograft mod-el in vivo. Mice were divided into three groups：control,shRNA-SC and shRNA-XRCC2 and exposed to X-ray radiation. The change of volume and weight of the xenografts were examined after receiving radiotherapy and the pathological analysis of tumor tissues were conducted. Results Tumor xenografts transfected with shRNA-XRCC2 in nude mice grew slowly. The xenograft volume in the shRNA-XRCC2 group was decreased significant-ly from day 12 to day 28 after radiotherapy compared with the control group（P〈0.01）. The xenograft weight in the shRNA-XRCC2 group was small-er than in the control group,with statistically significant difference（t=18.843,P〈0.01）. The inhibited rate of xenografts in the shRNA-XRCC2 group（56.25%）,was markedly higher than that in the shRNA-SC group（4.69%）. Pathological analysis of colonic transplanted carcinoma showed that nuclear atypia was not obvious,karyokinesis was decreased and small areas of necrosis were present in tumor xenografts treated with shRNA-XRCC2 transfection. Conclusion XRCC2 gene silencing combined with radiation has significant inhibition effect on colonic transplanted carcino-ma in nude mice.