目的：探讨CDX2基因表达对结肠癌细胞生长的影响。方法：将体外转染CDX2-shRNA慢病毒、空慢病毒载体及无转染的人结肠癌细胞系SW480和HT29接种到裸鼠皮下，制备皮下移植瘤模型，观察各组移植瘤的生长情况，28 d后处死裸鼠，剥取移植瘤称重，并分别用免疫组化、Western blot检测各组移植瘤组织Ki-67与CDX2的表达。结果：与各自空白对照组（无转染的SW480或HT29细胞移植）比较，两个干扰组（转染CDX2-shRNA慢病毒的SW480或HT29细胞移植）移植瘤生长速度均明显加快、移植瘤质量明显增加（SW480：679.11 mg vs. 379.36 mg；HT29：715.78 mg vs. 427.07 mg），瘤组织Ki-67蛋白表达水平明显升高、CDX2蛋白表达明显下调（均P<0.05）。两个阴性对照组（转染空慢病毒载体的SW480或HT29细胞移植）的各指标与各自空白对照组间均无明显差异（均P>0.05）。结论：抑制CDX2基因的表达能促进人结肠癌细胞的裸鼠体内的生长，故CDX2可能是一种重要的抑癌基因。
Impact of CDX2 gene interference on growth of colon cancer cells in nude mice
Objective: To investigate the effect of CDX2 gene expression on growth of colon cancer cells. Methods: Human colon cancer HT29 and SW480 cells transfected with lentiviral vectors expressing CDX2-shRNA, or empty lentiviral vectors or without any transfection were transplanted subcutaneously into nude mice to generate tumor xenografts, respectively. Then the growth of the xenografts in the three groups of mice was observed. At 28 d after transplantation, the mice were sacrificed and their xenografts were isolated and weighed, and the expressions of Ki-67 and CDX2 were determined by immunochemical staining and Western blot, respectively. Results: In either interference group (transplantation of HT29 or SW480 cells transfected with lentiviral vectors expressing CDX2-shRNA) compared with corresponding blank control (transplantation of HT29 or SW480 cells without any transfection), the tumor growth speed was significantly enhanced, the tumor weight was significantly elevated (SW480: 679.11 mg vs. 379.36 mg; HT29: 715.78 mg vs. 427.07 mg) and the Ki-67 protein expression was significantly increased, while the CDX2 protein expression was significantly upregulated in the tumor tissue (all P<0.05). No significant difference was found in any of above parameters between the two negative control groups (transplantation of HT29 or SW480 cells transfected with empty lentiviral vectors) and their blank control groups (all P>0.05). Conclusion: Inhibition of CDX2 gene expression can promote the growth of human colon cancer cells in nude mice, so CDX2 is probably an important cancer suppressor gene.