胃癌组织中肿瘤相关基因甲基化及其表达与叶酸和代谢酶MTHFR基因多态性的关系  

Methylation and expression of tumor-related genes and their associations with folate and MTHFR gene polymorphisms in gastric cancerous tissues

作　　者：翁玉蓉[1] 房静远[1] 孙丹凤[1] 陈朝飞[1] 陆嵘[1] 顾伟齐[1] 朱红音[1] 

机构地区：[1]上海交通大学医学院附属仁济医院上海市消化疾病研究所,上海市200001

出　　处：《世界华人消化杂志》2006年第22期2192-2198,共7页World Chinese Journal of Digestology

基　　金：国家自然科学基金资助项目;No.30470781;上海市科委重大项目;No.04DZ14006;上海市重点学科建设项目;No.Y0205

摘　　要：目的:探讨人胃癌组织中癌基c-myc,抑癌基因p16INK4A,p21WAF1,错配修复基NhMLH1和hM2SH2的甲基化状态及其表达与叶酸、MTHFR基因多态性的关系．方法:胃癌38例手术切除标本的癌区、癌旁和外周正常黏膜组织,运用FOL ACS:180自动化学发光系统测定叶酸含量,PCR-RFLP技术检测MTHFR基因677(C→T)和1298(A→C)两个常见多态,并分别以Real—time RT-PCR和甲基化特异性PCR (MSP)技术检测肿瘤相关基因的表达和甲基化状态．结果:c-myc表达升高,p16INK4A,hMLH1和hMSH2表达降低的胃癌黏膜组织其基因启动子区异常甲基化．p21WAF1,hMSH2表达降低, p16INK4A高甲基化者叶酸水平明显降低,c-myc低甲基化和表达升高者中均存在低叶酸水平．MTHFR 677CC基因型的胃癌黏膜组织p16INK4A甲基化升高且表达降低,而其余肿瘤相关基因的甲基化及其表达与MTHFR两个常见多态均无明显相关性．结论:DNA甲基化在胃癌的发生、发展中具有重要作用,叶酸水平和MTHFR基因多态性通过影响部分肿瘤相关基因的甲基化状态而调控其表达．AIM： To investigate the methylation and expression of c-myc oncogenes, p16^INK4A, p21^WAF1, hMLH1 and hMSH2 tumor suppressor genes, and their associations with folate and methyl enetetrahydrofolate reductase （MTHFR） gene polymorphisms in gastric cancerous tissues.METHODS： Paired samples of primary gastric cancer and corresponding para-cancerous, noncancerous gastric mucosa were obtained from surgically resected specimens of 38 patients, and the latter were used as controls. Folate concentration was detected by FOL ACS： 180 automated chemiluminescence system. Two common polymorphisms of MTHFR gene were analyzed by polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP）. The mRNA expression of tumor-related gene was detected by real-time reverse transcription-PCR （RT-PCR）. The methylation status of gene promoter was determined by methylation-specific PCR （MSP）.RESULTS： Up-regulation of c-myc, down-regulation of p16^INK4A, hMLH1 and hMSH2 expression were associated with the aberrant methylation of gene promoters in gastric canceous mucosae, while p21^WAF1 expression was not. Downregulation of p21^WAF1 and hMSH2 expression, hypermethylation of p16^INK4A were associated with low folate level. Over-expression and hypomethylation of c-myc coexisted with low folate level. 677CC genotype of MTHFR showed hypermethylation and down-regulation of p16^INK4A expression, and there was no significant relationship between the two common polymorphisms of MTHFR and the methylation and expression of the other tumor-related genes.CONCLUSION： DNA methylation plays an important role in human gastric carcinogenesis. Folate level and MTHFR gene polymorphisms may regulate the expression of tumor-related genes by affecting the methylation status.

关 键 词：胃癌 肿瘤相关基因 DNA甲基化 叶酸 MTHFR 基因多态性 

分 类 号：R735.2[医药卫生—肿瘤]