构建携带沉寂Survivin基因表达特异性siRNA的重组腺病毒载体，观察其在荷瘤动物体内对Survivin基因的表达以及对瘤细胞放射敏感性的影响。方法： 设计合成针对Survivin基因序列的siRNA，构建并重组腺病毒AdEGFPsiRNA。建立裸鼠SMMC 7721肝癌移植瘤模型，分5组进行实验，siRNA+放疗组和siRNA组以AdEGFPsiRNA瘤内多点注射，siRNA(－)组以AdEGFPsiRNA(－)瘤内多点注射，隔日1次，每次2×108 pfu/100 μl，共5次；单纯放疗组和空白对照组以等量生理盐水代替病毒注射；于第10、12、14、16天siRNA+放疗组和单纯放疗组给予5 Gy/次的照射；定时测量瘤体体积；观察周期结束，取瘤组织免疫组化检测Survivin蛋白的表达。结果： 成功构建并重组表达Survivin基因特异性siRNA序列和绿色荧光蛋白（EGFP）报告基因的腺病毒AdEGFPsiRNA。裸鼠SMMC 7721移植瘤在注射AdEGFPsiRNA后生长受到明显抑制，抑瘤率为56.2%；AdEGFPsiRNA病毒治疗和放疗结合，可将抑瘤率提高到82.6%。移植瘤组织免疫组化检查显示，特异性siRNA显著降低了肝癌细胞Survivin的表达。结论： Survivin特异性siRNA能够沉寂其基因的表达和抑制肿瘤的生长，同时可以提高肿瘤细胞的放射敏感性，改善治疗效果。

To construct a recombinant adenoviral vector carrying the specific siRNA of Survivin gene, and to observe its effect on the expression of Survivin gene and on the radiosensitivity of cancer cells in tumorbearing mice. Methods: The specific siRNA of Survivin gene was designed and synthesized, and a recombinant adenovirus AdEGFPsiRNA was subsequently constructed. SMMC 7721 xenograft models were established with nude mice and were divided into the following 5 groups: siRNA+radiotherapy and siRNA groups (intratumoral injection of AdEGFPsiRNA), siRNA(-) group (injected every other day with AdEGFPsiRNA\[-\], 2×108 pfu/100 μl per time, total 5 times), pure radiotherapy group and blank control groups (injected with the same volume of normal saline). On day 10, 12, 14, and 16, the mice in siRNA+radiotherapy and pure radiotherapy groups were given 5 Gy/time radiotherapy. The tumor volumes were measured regularly. The expression of Survivin in tumor tissues was determined immunohistochemically. Results: Adenovirus AdEGFPsiRNA harboring the specific siRNA of Survivin gene and enhanced green fluorescent protein gene (EGFP) was successfully recombined. The growth of SMMC 7721 xenografts in nude mice was inhibited after injecting AdEGFPsiRNA, with the inhibition rate being 56.2%. The inhibition rate in AdEGFPsiRNA therapy + radiotherapy increased to 82.6%. Immunohistochemistry study showed that the specific siRNA markedly silenced the expression of Survivin gene in hepatocarcinoma cells. Conclusion: The specific siRNA can markedly silence Survivin gene and subsequently inhibit the growth of cancer; meanwhile, it can also increase the radiosensitivity of cancer cells so as to improve the treatment effect.

R730.3

国家自然科学基金资助项目(No. 30572149)