中文摘要：

胃癌是人类最常见的肿瘤之一,其发病机制尚不完全清楚.微小RNA（microRNA,miRNA）是一组最近发现的长度为22个核苷酸左右的非编码RNA,具有负性调控基因表达的功能.本文对miRNA在胃癌发生中的作用及其表达调控机制进行综述.不断有文献显示,miRNA在多种肿瘤（包括胃癌）的发生过程中发挥着重要作用.作者和其他研究人员发现,miRNA的表达异常（如：miR-421和miR-21的上调或/和miR-31和miR-218的下调等）与胃癌的发生相关,提示miRNA是胃癌发生的重要因素.目前,miRNA表达的分子机制尚未完全明了.最近研究较清楚地显示,miRNA的表达受到DNA甲基化和组蛋白修饰等机制的调控.这说明,胃癌相关miRNA的表达水平受到表观遗传机制的调控。

英文摘要：

Gastric cancer is one of the most common cancers in human.The tumorigenesis of this type of cancer is poorly understood.Recently,microRNAs（miRNAs） have been identified as a group of non-coding RNAs having ～ 22 nucleotides to downregulate gene expression.In this review,the role of miRNAs in the development of gastric cancer and the mechanisms of their expression were summarized.Increasing evidence from literatures has indicated that miRNA play an important role in the development of various cancers,including gastric cancer.We and others have demonstrated the association of gastric cancer with the abnormality of miRNA expression,such as up-regulation of miR-421 and miR-21 and /or down-regulation of miR-31 and miR-218,suggesting that these miRNAs are oncogenic factors for gastric cancer.To date,the molecular mechanisms of miRNA expression have not been well studied,but recent studies have clearly shown that miRNA expression is regulated by DNA methylation and histone modification,indicating that the levels of miRNAs in gastric cancer may be controlled by the epigenetic mechanisms.