肿瘤是严重威胁人类健康的疾病之一,近年来大量的研究表明:肿瘤的发生不但存在遗传学上的改变,而且存在表遗传学的改变[1]。表遗传学的改变主要包括DNA甲基化和组蛋白修饰。在哺乳动物中,DNA甲基化是指在DNA甲基化转移酶催化下,以S-腺苷甲硫氨酸(SAM)为甲基化供体,将甲基转移到 Tumor is a serious threat to human health diseases, in recent years, a large number of studies have shown that: the occurrence of tumors not only there is a genetic change, but there are epigenetic changes [1]. Epigenetic changes include DNA methylation and histone modification. In mammals, DNA methylation refers to the use of S-adenosylmethionine (SAM) as a methylated donor catalyzed by DNA methylase to transfer the methyl group to