靶向XIAP的siRNA抑制结肠癌LoVo细胞体内外的增殖

目的：研究siRNA干扰X连锁凋亡抑制蛋白（Xlinked inhibitor of apoptosis protein, XIAP）基因表达对结肠癌细胞LoVo体内外增殖的影响。方法：构建XIAP真核表达干扰载体pSil2.1shXIAP1和pSil2.1shXIAP2，脂质体转染结肠癌细胞株LoVo，G418筛选出稳定转染LoVoshXIAP2细胞。RTPCR和Western blotting方法检测XIAP mRNA和蛋白的表达。MTT法和平板克隆形成实验检测LoVo细胞的增殖；流式细胞仪检测细胞的凋亡；裸鼠移植瘤模型观察XIAP表达下调对结肠癌体内增殖活性的影响。结果：LoVoshXIAP2细胞中XIAP mRNA和蛋白表达水平均显著下调。相对于对照组细胞，LoVoshXIAP2细胞的增殖和克隆形成率显著降低(P<0.01），凋亡率显著增加（P<0.01）。 LoVoshXIAP2移植瘤组织中XIAP蛋白表达明显下调，LoVoshXIAP2移植瘤生长显著抑制（均P<0.05）。结论：pSil2.1shXIAP2能够抑制结肠癌LoVo细胞中XIAP蛋白的表达，抑制LoVo细胞体内外的增殖，有望成为结肠癌免疫治疗的新手段。

XIAP targeting siRNA inhibits proliferation of colorectal cancer cells in vitro and in vivo

Objective:To investigate the effect of XIAP (X-linked inhibitor of apoptosis protein)-targeting siRNA on the proliferation of LoVo colorectal cancer cells in vitro and in vivo. Methods: The XIAP-targeting siRNA pSil2.1-shXIAP1 and pSil2.1-shXIAP2 eukaryotic vectors were constructed and were transfected into LoVo cells using Lipofectamine; the stable transfectants LoVo-shXIAP2 were selected by G418. The expressions of XIAP mRNA and protein were determined by RT-PCR and Western blotting. The proliferation of LoVo cells was determined by MTT and colony formation assay. Cell apoptosis was examined by FCM. The influence of XIAP knockdown on the proliferation of LoVo cells in vivo was observed in LoVo-bearing nude mice. Results: The expressions of XIAP mRNA and protein in LoVo-shXIAP2 cells were significantly down-regulated in LoVo-shXIAP2 cells. Compared with un-transfected LoVo cells, the proliferation and colony formation abilities of LoVo-shXIAP2 cells were significantly inhibited (P<0.05); the apoptosis rate of LoVo-shXIAP2 cells was significantly increased (P<0.05). The expression of XIAP protein in LoVo-shXIAP2 implanted tumors was down-regulated and the growth of tumors was significantly inhibited (all P<0.05). Conclusion: pSil2.1-shXIAP2 plasmid can down-regulate the expression of XIAP in LoVo cells and inhibit proliferation of LoVo cells in vitro and in vivo, making XIAP-targeting siRNA a potential new agent in immune therapy of colorectal cancer.