EZH2在乳腺癌中相互作用蛋白及其作用机制研究

EZH2（enhancer of zeste homolog 2）is overexpressed in many types of tumors including breast cancer and is implicated in the invasion and progression of cancer cells. EZH2 exerts its function as a transcriptional repressor through modification of the chromatin structure. The more interesting point is EZH2 could also act as a transcriptional activator through interacting with nonhistone proteins to promote expression of a subset of genes associated with cancer cell proliferation and agressiveness. Identification of EZH2 interacting proteins will contribute to develop new therapy stratigies targeting EZH2. In our preliminary work, a breast cancer cell line in which the endogenous EZH2 is replaced by Flag-tagged EZH2 is constructed for indetificaton of proteins interating with EZH2 from tumor tissue grown in nude mouse. In this project, we will set up xenograft nude mouse experiment using the former cell line. Subsequently, the tumor tissue will be used for co-immunoprecipitation of EZH2 interaction proteins which will be confirmed by using mammalian cell two hybrid system. Based on above research, the new mechanisms by which EZH2 and its interaction proteins exert in breast cancer cells will be elucidated by gene silencing, chromatin co-immunoprecipitation, identification of methylation site, expression pattern of regulated genes and phenotype analysis of breast caner cells.These research will provide new directions and ideas for anticancer therapy targeting EZH2.

EZH2（enhancer of zeste homolog 2）在包括乳腺癌在内的多种肿瘤细胞中过表达，并且其过表达与肿瘤的恶性程度相关。EZH2通过甲基化修饰组蛋白沉默抑癌基因转录；更有意义的是：过表达的EZH2也可以通过与非组蛋白相互作用并甲基化修饰这些蛋白激活肿瘤增殖及恶化相关基因的表达。研究EZH2与转录因子相互作用活化基因转录的分子机制将有助于理解EZH2的功能及开发靶向EZH2的新的治疗方法。我们前期工作已经构建了用于在裸鼠成瘤组织内高效鉴定EZH2相互作用蛋白的细胞系。本课题拟利用此细胞系在裸鼠体内成瘤，并从瘤组织内鉴定EZH2相互作用蛋白组，利用哺乳细胞双杂交系统确定其相互作用；在此基础上，我们将通过基因表达沉默、染色体免疫共沉淀、甲基化位点鉴定、致病基因表达分析等方法去研究EZH2新的相互作用蛋白或甲基化底物在乳腺癌中的分子机制，为靶向EZH2的治疗提供新的方向和思路。