中文摘要：

目的建立人胃癌裸鼠移植瘤模型，探讨Cdx2基因RNA干扰（RNAi）的重组慢病毒载体（pLL-Cdx2-siRNA）对人胃癌细胞MGC-803裸鼠移植瘤Cdx2基因表达和肿瘤生长的影响。方法建立人胃癌细胞MGC～803裸鼠移植瘤模型，随机分为实验组（pLL—Cdx2-siRNA组），空载体组p（pLL3．7组）和生理盐水组。隔天向各组动物肿瘤内分别注射Cdx2基因沉默的重组慢病毒载体pLL～Cdx2-siRNA、空载体pLL3．7或生理盐水0．2mL，共6次，测量各组肿瘤体积的大小；11d后处死裸鼠，应用半定量逆转录-聚合酶链反应（RT—PCR）和Westernblot技术检测移植瘤中Cdx2基因的表达，脱氧核苷酸末端转移酶介导的缺1：2末端标记（TUNEL）技术检测肿瘤细胞的凋亡。结果与生理盐水组和空载体组相比，实验组的肿瘤生长速度明显减慢（P〈0．05），肿瘤细胞Cdx2mRNA和蛋白表达明显下降（P〈O．05）；实验纽肿瘤细胞的凋亡指数（16．7±5．6）％明显高于空载体组（10．5±4．1）％和生理盐水组（11．2±4．3）％（P〈0．05）。结论慢病毒载体pLL～Cdx2-siRNA瘤内注射可抑制人胃癌细胞MGC-803裸鼠移植瘤的生长。

英文摘要：

[ Objective ] To study the effects of the recombinant lentiviral vector for RNA interference （RNAi） of Cdx2 gene （pLL-Cdx2-siRNA） on the expression of Cdx2 gene and the growth of subcutaneous tumor of human gastric cancer cell line MGC-803 in nude mice. [ Methods ] BALB/C nude mice were inoculated subcutaneously with MGC-803 cells to establish the subcutaneous tumor model of gastric carcinoma. The mice were randomly divided into experimental group （pLL-Cdx2-siRNA group）, vector group （pLL3.7 group） and NS group, pLL-Cdx2-siRNA, vector pLL3.7 or NS （0.2 mL per time） were injected individually every two days. The volume of tumor was measured and the expression of Cdx2 was detected by semi-quantitative reverse transcription polymerase chain reaction （RT- PCR） and Western blot. The apoptosis of tumor was measured by in situ end labeling technique （TUNEL）. [ Results ] The mean rate of tumor growth in the experimental group was much slower than that in the vector group and NS group （P 〈0.05）. Cdx2 mRNA and protein in the experimental group decreased （P 〈0.05）. The apoptotic rate in the experimental group was significantly higher than that in the other two groups （P 〈0.05）. [ Conclusion ] Intra-tumor injection of pLL-Cdx2-shRNA has a significantly inhibitory effect on the growth of subcutaneous tumor of human gastric cancer in nude mice.