腺病毒介导的环氧合酶-2反义RNA对肝癌细胞株生长的影响

The effects of adenovirus-mediated human COX-2 antisense RNA on the growth of hepatocellular carcinoma

目的探讨环氧合酶-2(COX-2)的表达与肝癌的关系,并构建表达人COX-2反义RNA的腺病毒载体,研究其对人肝癌细胞生长的抑制作用。方法采用免疫组织化学法探讨34例肝癌组织COX-2 的表达与肝癌病理特征的关系。采用基因重组法把人COX-2的cDNA片段反向克隆于穿梭质粒pHCMVSP1A,获得pAd-AShcox-2,通过脂质体与pJM17共转染293细胞,经同源重组产生编码COX-2反义RNA的重组腺病毒--Ad-AShcox-2。经聚合酶链反应法鉴定为阳性克隆者大量扩增、纯化,转染人肝癌细胞株SMMC-7402和SMMC-7721,采用免疫细胞化学、细胞集落形成率及流式细胞术检测其对肝癌细胞生长、凋亡及细胞周期分布的影响。结果34例肝癌组织中有28例COX-2高度表达,阳性率达82.4%; COX-2的表达水平与肝癌的病理分级有关,与甲胎蛋白、细胞类型、有无肝内转移无关。成功构建、扩增、纯化得到编码COX-2反义RNA的重组腺病毒Ad-AShcox-2,滴度达1.06×1012PFU/ml;Ad-AShcox- 2转染两种肝癌细胞株后,发现高度表达COX-2的SMMC-7402 COX-2表达水平明显降低,细胞凋亡率明显增加,出现G1期阻滞,与Ad-LacZ组及空白对照组比较差异有统计学意义(P<0.05);而不表达COX- 2的SMMC-7721变化不明显。细胞集落形成实验显示SMMC-7402细胞集落形成率较低(2.7%±0.94%);

Objective To investigate the relationship between the expression of COX-2 and liver cancer and construct a recombinant adenovirus encoding human COX-2 antisense RNA, and then to investigate its effects on liver cancer cell proliferation. Methods The expression of COX-2 in 34 cases of hepatocellular carcinoma and in SMMC-7402 and SMMC-7721 cell lines was studied by using immunohistochemical techniques. The shuttle plasmid encoding anti-sense COX-2 was constructed by using cloning COX-2 cDNA fragment in the reverse direction into the pHCMVSPIA. Then the plasmid pJM17 and the shuttle plasmid were co-transferred into 293 cells with lipofectamine for homologous recombination to acquire recombinant adenovirus (Ad-AShcox-2), which was confirmed by PCR. Human hepatocellular carcinoma cell lines SMMC-7402 and SMMC-7721 were transduced in vitro. The cell apoptosis and cell cycle were analyzed by flow cytometry. The cell proliferation was determined by colony-forming efficiency. Results We observed COX-2 expression in 82.4% of the hepatocellular carcinomas and SMMC-7402 cell line, but no COX-2 expression in the SMMC-7721 cell line. In addition, the recombinant adenovirus encoding anti-sense COX-2 fragment Ad-AShcox-2 was obtained with a titer of 1.06×1012 PFU/ml. Ad-AShcox-2 reduced the expression of COX-2 and enhanced the percentage of cells into G1/G0 phase in the SMMC-7402 cell line. The difference of apoptotic index between the Ad-AShcox-2 group and the control group was statistically significant (P < 0.05) in SMMC-7402 but not in SMMC-7721. Similarly, colony-forming rates of SMMC-7402 and SMMC-7721 cell lines after Ad-AShcox-2 being transferred were (2.7±0.94)% and (33.6±4.24)%, respectively. Conclusion By reducing the expression of COX-2 in hepatocellular carcinoma cells with the expression of COX-2, the cells could be inhibited.