错配修复基因MLH1激活p53和线粒体凋亡通路参与雌激素诱导的结肠癌细胞凋亡  

Mismatch Repair Gene MLH1 Involved in Estrogen-induced Apoptosis of Colonic Cancer Cells by Activating p53Signaling and Mitochondrial Apoptotic Pathway

作　　者：吕晨曦[1,2] 王德智[1] 金鹏[1] 杨欣艳[1] 盛剑秋[1] 

机构地区：[1]北京军区总医院消化内科,100700 [2]大连医科大学研究生院

出　　处：《胃肠病学》2014年第5期279-283,共5页Chinese Journal of Gastroenterology

基　　金：国家自然科学基金资助(81201958)

摘　　要：临床和流行病学研究显示雌激素替代治疗可降低绝经后妇女的结直肠癌发生风险。前期研究发现雌激素能上调结肠癌细胞的错配修复(MMR)基因MLH1表达,在MLH1基因缺失的结肠癌细胞中再表达MLH1能明显增强雌激素诱导的细胞凋亡。目的:探讨MLH1参与雌激素诱导结肠癌细胞凋亡所涉及的信号通路以及p53及其相关基因在此凋亡通路中的作用。方法:以含人野生型MLH1(hMLH1)全长cDNA的质粒转染MLH1基因缺失的人结肠癌细胞株HCT116。以转染空质粒的HCT1 16细胞作为对照,在有或无雌激素作用的条件下,采用电泳法检测凋亡DNA Ladder,蛋白质印迹法检测p53等凋亡相关蛋白表达。结果:转染hMLH1后,10^(-8)mol/L雌二醇(E_2)能明显诱导HCT116细胞凋亡。转染hMLH1并经E_2处理的HCT116细胞(D组)与经E_2处理但未转染hMLH1的HCT116细胞(B组)相比,其caspase-3、caspase-9、p53、Bax、胞质细胞色素C蛋白表达均显著增强,D组上述蛋白表达亦均高于转染hMLH1但未经E_2处理的HCT116细胞(C组)。结论:MMR基因MLH1主要通过激活p53和线粒体凋亡通路参与雌激素诱导的人结肠癌细胞株HCT116凋亡。Background：Clinical and epidemiological studies revealed that estrogen replacement therapy was associated with a significant reduction in risk of colorectal cancer in postmenopausal women.In our previous studies,estrogen increased the expression of mismatch repair （MMR）gene MLH1 in colonic cancer cells,and re-expression of MLH1 in MLH-deficient colonic cancer cells significantly increased the estrogen-induced apoptosis.Aims：To investigate the signaling pathway implicated in the MLH1-mediated apoptosis in colonic cancer cells induced by estrogen and the roles of p53 and its related genes in this apoptotic pathway.Methods：Plasmid containing wild type human MLH1 （hMLH1）full length cDNA was transfected into MLH1-deficient human colonic cancer cell line HCT116.By using HCT116 cells transfected with empty plasmid as controls,the apoptotic DNA ladder was determined by electrophoresis and the expressions of p53 and other apoptosis-related proteins were assessed by Western blotting under the condition with or without estrogen stimulation. Results：17β-estradiol （E2 ）at the concentration of 10 -8 mol/L induced significant apoptosis in HCT116 cells transfected with hMLH1.In HCT116 cells transfected with hMLH1 and stimulated with E2 （group D）,the protein expressions of caspase-3,caspase-9,p53,Bax and cytoplasmic cytochrome C increased significantly when compared with HCT116 cells stimulated with E2 only （group B）;expressions of the abovementioned proteins were also higher in group D than in group C （transfected with hMLH1 only）.Conclusions：MMR gene MLH1 is involved in estrogen-induced apoptosis of human colonic cancer cell line HCT116 by activating p53 signaling and mitochondrial apoptotic pathway.

关 键 词：DNA错配修复 基因 MLH1 雌激素类 基因 P53 线粒体凋亡通路 结肠肿瘤 

分 类 号：R735.34[医药卫生—肿瘤]