中文摘要：

Polyeombgroup（PcG）蛋白家族是一组在胚胎发育中起作用的基因调控因子，根据其功能不同分为polycomb repressive complex1（PRCl）和PRC2两种蛋白质复合物。PRC2是一个作用于组蛋白H3赖氨酸位点K27的高度保守的组蛋白甲基转移酶，Zeste基因增强子同源物2（EZH2）是构成PRC2蛋白复合物中的一个催化亚基。近期大部分肿瘤研究表明，EZH2在多种癌组织过表达，如前列腺癌、乳腺癌。该文阐述EZH2的生物功能及与多种肿瘤组织的密切关系，讨论EZH2与其他表观遗传修饰酶间的关系和EZH2过表达的结果及其在肿瘤形成中的作用。

英文摘要：

The polyeomb group（PeG） protein tinnily is a group of gene regulatory elements playing roles in enabryonic development, functioning in two distinct protein complexe： polyeomb-ropressivc complex 1 （ PRC1 ） and polyeomh-repressive complex 2 （ PRC2 ）. EZH2 is the catalytic subunit of PRC2, which is a highly conserved histone methyhransferase that targets lysine-27 of histone H3. Most studies on human tumors show that EZH2 is over-expressed in a variety of tumors, such as prostate cancer,breast cancer. Here is to make a review of the basic molecular biology of EZH2 and its relationships with different cancers, and discuss EZH2 connections to other epigenetic modifying enzymes, as well as the consequences of EZH2 overexpres- sion and its roles in tumorigenesis.