目的 研究含辐射敏感Egr-1启动子介导Smac基因的重组质粒pshuttle-Egr1-hSmac对辐射人乳腺癌MCF-7细胞的致敏作用及细胞周期进程的影响.方法 将其质粒经脂质体转染到MCF-7细胞中,24 h后利用克隆形成法计算存活分数,评价细胞的辐射敏感性;利用流式细胞术检测X射线照射后细胞周期进程的变化.结果 MCF-7细胞转染质粒24 h后,经0、2、4、6、8和10 Gy X射线照射后14 d,对照和pshuttle组细胞存活分数基本一致,而转染质粒的细胞存活分数明显低于对照组(P＜0.05,P＜0.01);通过相关与回归分析,对照和pshuttle组细胞D0值分别为3.27和3.28,而转染质粒的D0值为2.1.pshuttle组各期细胞百分数变化不明显;而转染质粒的G0/G1期细胞百分数明显高于对照和pshuttle组,S期细胞明显降低(P＜0.01,P＜0.001);2 Gy照射后24 h各组G0/G1期细胞百分数增加,S期细胞降低,其中以转染质粒的细胞变化最明显(P＜0.05,P＜0.01).结论 pshuttle-Egr1-hSmac质粒能够增强人乳腺癌MCF-7细胞的辐射敏感性,可致细胞G1期阻滞,暗示Smac基因对乳腺癌的放疗具有辐射增敏作用.%Objective To study the effects of Smac recombinant plasmid pshuttle-Egrl-hSmac mediated by radiation-sensitive promoter Egr-l on the radiosensitization of human breast cancer MCF-7 cells and cell cycle progression .Methods The surviving frac-tion was calculated by clone forming ,the cell radiaton sensitivity was evaluated ,and the cell cycle change was measured by flow cy-tometry 24 h after the plasmid transfected into MCF-7 cells with liposome .Results MCF-7 cells 24 h after transfected with the plas-mid were irradiated by 0 ,2 ,4,6,8 and 10 Gy X-rays ,the surviving fraction of MCF-7 cells in the control and pshuttle groups was basi-cally same ,while that in the plasmid group decreased significantly 14 d after irradiation as compared with that in the control (ρ＜0.05, ρ＜0 .01) ; the cell Do values in the control and pshuttle groups were 3 .27 and 3 .28 respectively ,through correlation and re-gression analysis ,while the cell Do value in the plasmid group was 2 .1 .The cell percentage change of every phase in the pshuttle group was not obvious ,but the percentage change of G0 /G1 phase cells in the plasmid group increased significantly and that of S phase cells decreased significantly as compared with that in the control and pshuttle groups (ρ＜0 .01, ρ＜0 .001) ; the cell percentage of G0 /G1 phase increased and that of S phase decreased in every group ,and the change was more significantly in the plasmid group 24 h after irradiation with 2 Gy (ρ＜0 .05 ,ρ＜0 .01) .Conclusion pshuttle-Egrr-Smac plasmid could enhance the radiation sensitivity of human breast cancer MCF-7 cells to induce the cell G1 arrest ,indicating Smac gene may have the radiosensitization on the radiotherapy of breaset cancer.
展开▼
