中文摘要：

目的：观察Cdx2小分子干扰RNA（Cdx2．siRNA）对人胃癌MGC．803细胞凋亡及Survivin、Caspase-9表达的影响。方法：设计合成针对Cdx2基因的siRNA寡核苷酸以及阴性对照siRNA。将人胃癌MGc-803细胞接种于培养板中，分为3组，正常对照组不作处理，阴性对照组和cdx2．siRNA组分别用LipofectamineTM2000将阴性对照siRNA或Cdx2．siRNA成功转染进细胞内。应用流式细胞仪检测转染24h时MGC．803细胞凋亡的变化，并应用RT—PCR和Westernblot技术检测胃癌MGC．803细胞中sunrivin和Caspase-9基因mRNA和蛋白的表达。结果：Cdx2．siRNA纽MGC．803细胞的凋亡率为（12．5±0．6）％．明显高于阴性对照组和正常对照组（P〈0．05）；Cdx2．siRNA组SurvivinmRNA和蛋白的表达量分别为（0．14±0．04）和（0．5l±0．12），明显低于阴性对照组和正常对照组（P〈0．05）；Cdx2．siRNA组Caspase．9mRNA和蛋白的表达量分别为（O．984-0．24）和（1．78±0．41），明显高于阴性对照组和正常对照组（P〈0．05）；而阴性对照组和正常对照组比较差异无统计学意义（P〉0．05）。结论：Cdx2．siRNA促进人胃癌细胞的凋亡，其机制可能与其抑制Survivin的表达、增强Caspase-9的活性有关。

英文摘要：

Objective To investigate the effects of small interference RNA targeting Cdx2 gene （Cdx2- siRNA） on apoptosis and Survivin and Caspase-9 expression of human gastric cancer MGC-803 cells. Methods Cdx2-siRNA or negative control siRNA was constructed and transfected into MGC-803 cells by using LipofectamineTM 2000. Gastric cancer MGC-803 cells were divided into three groups： normal control group, negative control group and Cdx2-siRNA group. The cell apoptosis was assessed by flow cytometry. Survivin and Caspase-9 mRNA and protein were detected by semi-quantitative reverse transcription polymerase chain reaction （RT-PCR） and Western blot. Results The apoptotic rate in Cdx2-siRNA group was （12.5 ~ 0.6）%, which was higher than that in negative control group and normal control group. Survivin mRNA and protein were downregulated while Caspase-9 mRNA and protein were upregulated in Cdx2-siRNA group. However, no significant difference was found between negative control group and normal control group. Conclusions Cdx2-siRNA may promote apoptosis of gastric cancer cells by Survivin downregulation and Caspase-9 upregulation in vitro.