中文摘要：

目的观察Cdx2小分子干扰RNA（Cdx2-siRNA）对人胃癌MGC-803细胞增殖及凋亡的影响。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，正常对照组不作任何处理，Cdx2-siRNA组和阴性对照组分别用Lipofectamine^TM2000将Cdx2-siRNA或阴性对照siRNA转染进细胞内。应用半定量逆转录-聚合酶链反应（RT—PCR）和Westernblot技术检测转染24h时胃癌MGC-803细胞中Cdx2mRNA和蛋白的表达，应用噻唑蓝（MTT）比色法检测24、36、48、60、72h的细胞活力，应用克隆形成实验检测转染7d时MGC-803细胞增殖的变化，应用流式细胞仪检测转染24h时MGC-803细胞周期和细胞凋亡的变化。结果Cdx2-siRNA或阴性对照siRNA成功转染进胃癌MGC-803细胞内；Cdx2-siRNA组Cdx2mRNA和蛋白的表达量分别为（0．07±0．01）和（0．15±0．02），明显低于阴性对照组和正常对照组（P〈0．05）；Cdx2-siRNA组细胞活力和增殖能力下降，24、36、48、60、72h的吸光度值分别为（0．125±0．003）、（0．193±0．005）、（0．223±0．005）、（0．267±0．003）、（0．315±0．006），克隆形成数为（51．4±3．2），均明显低于阴性对照组和正常对照组（P〈0．05）；而且，Cdx2-siRNA组细胞凋亡率为（12．5±0．6）％，G。／G，期比例为（73．1±7．8）％，明显高于阴性对照组和正常对照组（P〈0．05）；阴性对照组和正常对照组比较，上述指标差异无统计学意义（P〉0．05）。结论Cdx2-siRNA可抑制人胃癌细胞的活力和增殖能力，其机制与诱导细胞凋亡、使细胞周期停滞有关。

英文摘要：

Objective To investigate the effects of small interference RNA targeting Cdx2 gene （Cdx2-siRNA） on proliferation and apoptosis of human gastric cancer MGC-803 cells. Methods Cdx2- siRNA or negative control siRNA was constructed and transfected into MGC-803 cells by using Lipofectamine^TM 2000. Gastric cancer MGC-803 ceils were divided into three groups： normal control group, negative control group and Cdx2-siRNA group. Cdx2 mRNA and protein were detected by using semi-quantitative reverse transcription polymerase chain reaction （RT-PCR） and Western blotting respectively at 24 h. The viability of cells was examined by using methyl thiazol tetrazolium （MTT） assay at 24, 36, 48, 60 and 72 h. The proliferation of cells was determined by colony formation assay at 7th day. The cell cycle progression and apoptosis were assessed by using flow cytometry at 24 h. Results Cdx2-siRNA and negative control siRNA were transfected into gastric cancer MGC-803 cells successfully. Cdx2 mRNA and protein in Cdx2-siRNA group were （0. 07 ±0. 01 ） and （0. 15 ±0. 02）, which were lower than in negative control group and normal control group. The viability of cells was （0. 125 ±0. 003）, （0. 193 ±0. 005）, （0. 223 ±0. 005）, （0. 267 ±0. 003） and （0. 315 ±0. 006） at 24, 36, 48, 60 and 72 h and the clones of ceils were （51.4 ± 3.2） in Cdx2-siRNA group, which were significantly lower than those in negative control group and normal control group. The apoptosis rate and the proportion of cells in G0/G1 phase in Cdx2-siRNA group were （12. 5 ± 0. 6）% and （73.1 ± 7. 8 ）% respectively, which were higher than in negative control group and normal control group. However, no significant difference was found between negative control group and normal control group. Conclusion Cdx2-siRNA can inhibit viability and proliferation of human gastric cancer cells by apoptosis-induced effect and cell cycle arrest.