Deng Da-Jun, Zhou Jin, Zhu Bu-Dong, Ji Jia-Fu, Harper Jeffrey C, Powell Steven M
Peking University Health Science Center and Beijing Institute for Cancer Research, Beijing, 100034, China.
World J Gastroenterol. 2003 Jan;9(1):26-9. doi: 10.3748/wjg.v9.i1.26.
To investigate CpG methylation and single nucleotide polymorphism (SNP) of a specific promoter region of hMLH1 in primary gastric carcinoma.
Primary gastric carcinomas (n=80), their corresponding normal mucosal samples, and gastric mucosal biopsies from normal/gastritis control patients (n=54) were used. Hypermethylation at -253 nt and -251 nt in relation with the translational start site and SNP of a silencing specific region (-339 nt-46 nt) in the hMLH1 promoter were analyzed by Bst UI-combined bisulfite assay (COBRA), denaturing high performance liquid chromatogram (DHPLC), and sequencing.
(A) The specific methylation at -253 nt and -251 nt was observed in 2 of 60 primary gastric carcinomas, but neither in all of the corresponding mucosa nor in normal/gastritis samples, by Bst UI-COBRA and DHPLC. (B) The hMLH1 promoter was methylated homogeneously in the xenograft of the primary gastric carcinoma with the methylated and unmethylated hMLH1. (C) The pattern of SNP at -93 nt of the hMLH1 promoter in 54 Chinese patients with gastric carcinoma was the same as that in the control patients: 51 % was A/G heteroalleles, 34 % and 15 % were A/A and G/G homoalleles, respectively.
Biallelic inactivation of hMLH1 by epigenetic silencing existed in human primary gastric carcinoma homogeneously. Hypermethylation of hMLH1 may play a role in the early stage of development of a few gastric carcinomas. The SNP at -93 nt is not related to the susceptibility of gastric carcinomas.
研究原发性胃癌中hMLH1特定启动子区域的CpG甲基化和单核苷酸多态性(SNP)。
使用80例原发性胃癌、其相应的正常黏膜样本以及来自正常/胃炎对照患者的胃黏膜活检样本(n = 54)。通过Bst UI联合亚硫酸氢盐分析(COBRA)、变性高效液相色谱(DHPLC)和测序,分析与翻译起始位点相关的-253 nt和-251 nt处的高甲基化以及hMLH1启动子中沉默特定区域(-339 nt - 46 nt)的SNP。
(A)通过Bst UI-COBRA和DHPLC检测,在60例原发性胃癌中有2例观察到-253 nt和-251 nt处的特定甲基化,但在所有相应黏膜以及正常/胃炎样本中均未观察到。(B)原发性胃癌异种移植中,hMLH1启动子在甲基化和未甲基化的hMLH1中均呈均匀甲基化。(C)54例中国胃癌患者中hMLH1启动子-93 nt处的SNP模式与对照患者相同:51%为A/G杂合等位基因,34%和15%分别为A/A和G/G纯合等位基因。
人类原发性胃癌中存在通过表观遗传沉默导致的hMLH1双等位基因失活。hMLH1的高甲基化可能在少数胃癌的早期发展中起作用。-93 nt处的SNP与胃癌易感性无关。