肿瘤基因启动子区异常甲基化与肿瘤的发生

肿瘤的发生和发展是一个与多基因、多步骤的致癌因素相关的复杂过程，包括了原癌基因及肿瘤抑制基因的改变、错配修复基因的突变、DNA甲基化和微卫星不稳定性。癌基因的低甲基化与抑癌基因的高甲基化在肿瘤发生、发展中的基因表达调控、基因结构的稳定等方面发挥重要作用。DNA甲基化是指生物体在DNA甲基转移酶的催化下，以S-腺苷甲硫氨酸（SAM）为甲基供体，将甲基转移到特定碱基上的过程。甲基化异常被认为是肿瘤的一个特征，是基因组中一种重要的表观遗传修饰，与肿瘤的发生、浸润及转移相关。基因局部甲基化模式的改变已成为令人瞩目的研究领域。本文就DNA甲基化及肿瘤基因启动子区甲基化研究的相关进展作简要综述。

Aberrant methylation of tumor gene promoter and tumorigenesis

Tumorigenesis and development is a complex process which relates to multi-gene, multi- step carcinogenic factors, includeing the proto-oncogene and tumor suppressor gene alterations, mutations in mismatch repair genes, DNA methylation and microsatellite instability. Oncogene hypomethylation and hypermethylation of tumor suppressor genes play an important role in tumor development, the regulation of gene expression, gene structure stability. DNA methylation is a process of methyl, which S-adenosyl methionine （SAM） as a methyl donor, transferred to the specific base under the catalysis of DNA methyltransferase. Methylation abnormality is considered to be one of the characteristics of the tumor and an important epigenetic modification in the genome, which associates with many of the malignant transformation of cells, tumor invasion and metastasis. The change of local gene methylation patterns has become a remarkable research field. This paper reviews the progress of DNA methylation and tumor gene promoter methylation.