靶向COX-2的siRNA抑制三种不同分化程度胃癌细胞生长及作用机制

Inhibitory effect of siRNA targeting COX-2 on the growth of gastric carcinoma cells of well, moderate or poor differentiation and its mechanism

目的:利用RNA干扰(RNAinterference,RNAi)技术在体外抑制COX2表达,研究其抑制三种不同分化程度的胃癌细胞(MKN28,SGC7901,BGC823)的可能性,探讨RNAi抑制胃癌生长与胃癌细胞分化程度的相关性.方法:设计靶向COX2基因的siRNA,构建重组表达质粒pTZU6+1siRNACOX2并导入胃癌细胞株,体外诱导RNAi,采用逆转录PCR(RTPCR)和Westernblotting检测COX2基因表达变化,MTT法检测细胞活力,原位末端标记(TUNEL)及透射电镜检测细胞凋亡,Westernblotting检测凋亡相关蛋白Bax和Bcl2的改变.结果:pTZU6+1siRNACOX2质粒导入细胞后,SGC7901和BGC823中COX2表达明显下调,细胞生长被抑制,并出现特征性的细胞凋亡,同时有Bax蛋白上调和Bcl2蛋白下调.对照组则无明显变化.结论:RNAi显著抑制胃癌细胞生长,可能与下调COX2基因表达和诱导细胞凋亡有关,其对中分化胃癌细胞的抑制作用最为显著,提示RNAi的作用可能依赖于胃癌细胞的分化程度.

AIM： To investigate the inhibitory effect of siRNA targeting COX-2 on the growth of gastric carcinoma ceils of well, moderate or poor differentiation （MKN-28, SGC-7901, BGC- 823） and related mechanism. METHODS： siRNA targeting COX-2 gene was designed, siRNA-COX-2 vector was constructed and transfected into gastric carcinoma cells to induce RNA interference. The changes of COX-2 were detected with RT-PCR and Western blotting. Cell viability was detected by MTT. Cell apeptosis was judged by TUNEL and electromicroscopy, and expressions of Bax and Bcl-2 were tested by Western blot. RESULTS： Both COX-2 expression and cell growth were inhibited in SGC-7901 and BGC-823 after transfection of siRNA-COX-2 vector into the cells. But, in MKN-28 , only COX-2 expression decreased. The obvious cell apoptosis both in SGC-7901 and BGC-823 was observed. Bax was up-regulated and Bcl-2 was down-regulated in SGC-7901 and BGC-823. In contrast, there were almost no chan- ges in control group in vitro. CONCLUSION： RNA interference inhibits the growth of gastric carcinoma ceils, which may be related to down-regulation of COX-2 and induction of cell apoptosis. The inhibitory effect of RNAi was relatively strong in SGC-7901, which indicated that the effect of siRNA was dependent on the differentiation degree of gastric carcinoma cells.