中文摘要：

目的观察携带人尾型同源盒转录因子2（Cdx2）基因沉默的重组慢病毒颗粒（Cdx2-RNAi-LV）对人胃癌耐顺铂细胞SGC-7901／DDP裸鼠皮下移植瘤中Survivin和C—myc表达的影响。方法建立人胃癌耐顺铂细胞SGC-7901／DDP裸鼠皮下移植瘤模型，36只裸鼠随机分成3组（n=12）：PBS组、LV-RNAi组、Cdx2．RNAi-LV组；各组瘤体内分别注射磷酸盐缓冲液、慢病毒颗粒（0．5×10^8TU／m1）、含Cdx2基因重组慢病毒颗粒（0．5×10^8TU／m1）相应药物100μl，1次／3d，共6次；同时所有裸鼠腹腔注射药物顺铂（25mg／kg），隔天1次，共10次；注射Cdx2-RNAi-LV病毒颗粒第20天后脱颈椎法处死裸鼠，完整切取肿瘤组织，并应用PT-PCR和Westernblot技术检测移植瘤中Survivin和C．myc基因的表达。结果Cdx2．RNAi．LV组、LV．RNAi组和PBS组的细胞均有Survivin、C—myc的mRNA和蛋白的表达，但各组细胞对应的Survivin、C—myc的mRNA和蛋白的表达水平有差别；Cdx2-RNAi—LV组Survivin、C．myc的mRNA和蛋白的表达量较PBS组和LV．RNAi组明显下调（P〈0．05），而PBS组和LV—RNAi组比较差异元统计学意义（P〉0．05）。结论Cdx2基因沉默重组慢病毒颗粒瘤内注射下调人胃癌耐顺铂细胞裸鼠移植瘤Survivin和C-myc表达，可能是Cdx2基因沉默逆转肿瘤的耐药性机制之一。

英文摘要：

Objective To investigate the effect of Cdx2 gene silencing of recombinant lentivirus particles （Cdx2-RNAi-LV） on expression of Survivin and C-myc in human gastric cancer SGC-7901/DDP resistant cells transplanted subcutaneously in nude mice. Methods The subcutaneous transplantated tumor models in nude mice were established with cell line SGC-7901/DDP of human gastric cancer. The 36 of model mice were randomly divided into 3 groups （n = 12） ： PBS group, LV-RNAi group, C dx2-RNAi-LV group, each group of tumors were respectively injected with phosphate buffer, the lentivirus particles （0. 5 ×10^8 TU/ml）, containing Cdx2 gene recombinant lentiviral particles （0. 5 ×10^8TU/ml） , the corresponding volume of drugs which were all equivalent 100 μl, once every three days for six times. And all mice were intraperitoneally injected with the drug cisplatin （25 mg/kg）, once every two days for ten times. After 20 days, all mice were sacrificed and subcutaneous tumors were taken out. Survivin and C-myc mRNA and protein were detected by semi-quantitative reverse transcription polymerase chain reaction （RT- PCR） and Western blot. Results Among groups of Cdx2-RNAi-LV, LV-RNAi and PBS, the mRNA and protein of Survivin and C-myc were all expressed in cells, but the corresponding expression levels of mRNA and protein in each group cells were not all the same. Compared with LV-RNAi group and PBS group, Survivin and C-myc mRNA and protein were downregulated in Cdx2-RNAi-LV group （ P 〈 0..05 ）. However, no significant difference was found be- tween LV-RNAi group and PBS group（P 〉 0.05 ）. Conclusion The Cdx2 Gene Silencing of recombinant lentivirus particles intratumorally injected cottld significantly downregulate the expression of Survivin and C-myc in gastric carci- noma transplanted tumor carried by nude mice, and the down-regulation of Survivin and C-myc expression perhaps is one of the Cdx2 gene silencing reversal of tumor resistance mechanisms.