CpG methylation of tumor suppressor genes occurs in the early stage of carcinogenesis. Detecting risk factors for aberrant CpG methylation is clinically important for predicting cancer development. DNA methyltransferase (DNMT) 3a is considered to play critical roles in the DNA methylation process during pathogenesis. In this study, we evaluated the association between DNMT3A polymorphisms (rs6733868 and rs13428812) and CpG methylation status in non-cancerous gastric mucosa. We determined the DNMT3A genotype and CpG methylation status of 4 genes (p14ARF, p16INK4a, DAPK, and CDH1) in 510 subjects without gastric cancer. Helicobacter pylori (HP) infection status was determined by the rapid urease test, urea breath test, speculum examination, or serum antibody test. We determined the DNMT3A genotype using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP). CpG methylation status was determined by methylation-specific polymerase chain reaction (MSP). When the methylated band was stronger than 10 ng/μL according to the DNA marker, we judged CpG island hypermethylation (CIHM) to be present. Associations between genotypes and susceptibilities were assessed by logistic regression analysis. The minor allele frequencies of both polymorphisms (rs6733868 and rs13428812) were lower in the CpG methylated groups of each of the 4 genes (p14ARF, p16INK4a, DAPK, and CDH1). Using a dominant genetic model, rs6733868 was significantly associated with the hypermethylation of each gene, whereas rs13428812 was associated with the methylation of 3 genes (all except p14ARF). When low-CIHM was defined as 1 or 2 CpG islands methylated and high-CIHM was defined as 3 or more CpG islands methylated, carrying the minor allele of rs6733868 was associated with both decreased low- and high-CIHM, and that of rs13428812 also was associated with a decrease. Comparing low-CIHM with high-CIHM, carrying the minor alleles of rs6733868 or rs13428812 was related to decreased susceptibility to high-CIHM. In HP-infected subjects, carrying the minor alleles of rs6733868 or rs13428812 had a significantly greater association with decreased susceptibility to high-CIHM. Our study indicates that polymorphisms of DNMT3A are associated with the accumulation of gene methylation in gastric mucosa. Carrying the minor alleles of rs6733868 or rs13428812 inhibits aberrant gene methylations, which are typically enhanced by HP infection.

中文翻译：

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的影响DNMT3A基因多态性对胃黏膜的CpG岛甲基化

抑癌基因的CpG甲基化发生在癌发生的早期。检测异常CpG甲基化的危险因素对于预测癌症的发展在临床上很重要。DNA甲基转移酶（DNMT）3a被认为在发病机理中的DNA甲基化过程中起关键作用。在这项研究中，我们评估了非癌性胃黏膜中DNMT3A多态性（rs6733868和rs13428812）与CpG甲基化状态之间的关联。我们确定了510例无胃癌的受试者的DNMT3A基因型和4个基因（p14ARF，p16INK4a，DAPK和CDH1）的CpG甲基化状态。通过快速尿素酶测试，尿素呼气测试，窥镜检查或血清抗体测试确定幽门螺杆菌（HP）感染状态。我们使用聚合酶链反应单链构象多态性（PCR-SSCP）确定了DNMT3A基因型。CpG甲基化状态通过甲基化特异性聚合酶链反应（MSP）确定。当DNA标记的甲基化带强于10 ng /μL时，我们判断存在CpG岛超甲基化（CIHM）。基因型和药敏性之间的关联通过逻辑回归分析进行评估。两种多态性（rs6733868和rs13428812）的次要等位基因频率在4个基因（p14ARF，p16INK4a，DAPK和CDH1）的CpG甲基化组中较低。使用显性遗传模型，rs6733868与每个基因的高甲基化显着相关，而rs13428812与3个基因的甲基化（除p14ARF以外的所有基因）相关。当低CIHM被定义为1个或2个甲基化的CpG岛而高CIHM被定义为3个或多个甲基化的CpG岛时，携带rs6733868的次要等位基因与降低的低和高CIHM相关，而rs13428812的等位基因也有所降低与减少有关。比较低CIHM与高CIHM携带rs6733868或rs13428812的次要等位基因与降低对高CIHM的敏感性有关。在HP感染的受试者中，携带rs6733868或rs13428812的次要等位基因与降低的对高CIHM的易感性具有显着更大的关联。我们的研究表明，DNMT3A的多态性与胃粘膜中基因甲基化的积累有关。携带rs6733868或rs13428812的次要等位基因可抑制异常的基因甲基化，这通常会因HP感染而增强。