Expression And Significance Of Methyltransferases In Gastric Cancer And Precancerous Lesion

Objectire:Gastric cancer is one of most common gastrointestinal tumors and its mechanism of carcinogenesis are not elucidated so far.DNA methylation aberrances may be involved in generation and progression of gastric cancer.The methylation of genomic DNA in malignant cell is catalyzed by DNA methyltransferases.It is aim for us to investigate the expression of Dnmt3A and Dnmt3B in gastric cancer and its premalignant lesions and explore the relationships between helicobacter pylori and DNA methyltransferasesMethods:Immunohistochemistry was used to detect the expression of Dnmt3A and Dnmt3B in 26 patients with gastric cancer,20 patients with premalignent lesions and 25 cases of controls with superficial gastritis.The relationship between expression of Dnmt3A and Dnmt3B in gastric cancers and their clinicopathological factors were analyzed.The infection of Helicobacter pylori were also detected in patients with premalignent lesions and persons with superficial gastritis.Results:The positive rates of expression of Dnmt3A in patients with gastric cancer(96.2%) were the significantly higher than in patients with premalignent lesions(65.0%),and persons with superficial gastritis(84.0%)(P＜0.05).The positive rates of expression of Dnmt3B in patients with gastric cancer(96.5%) were the significantly higher than in patients with premalignent lesions(55.0%),and persons with superficial gastritis(80.0%)(P＜0.05).The positive rate of expression of Dnmt3A and Dnmt3B in patients with gastric cancer were not associated with age,tumor size, infiltration,histological classification and local recurrence(P＞0.05).The positive rate and expression level of Dnmt3A and Dnmt3B in patients with intestinal metaplasia were not associated with infection of Helicobacter pylori.Conclusion:1.It was showed that the high expression of Dnmt3A and Dnmt3B in gastric cancer tissues.Dnmt3A and Dnmt3B may be involved in carcinogenesis of gastric cancer by inducing genomic DNA hypermethylaton that was associated with inactive anti-oncogene.Dnmt3A and Dnmt3B may be involved in differentiation of gastric cancer.2.The expression of Dnmt3A and Dnmt3B in lesion precancerous are not high indicating that they are not the prophase event of gastric cance.3.Dnmt3A and Dnmt3B were not associated with cell differentiation or invasion.4.The infection of Helicobacter pylori may not have effect on expressions of Dnmt3A and Dnmt3B.