EP300-ZNF384融合基因在急性白血病中发病机制的研究

EP300 regulates the activity of various target genes，ZNF384, which may function as a transcription factor，encodes a C2H2-type zinc finger protein. These two genes above play important roles in proliferation and differentiation of cells, as well as the inhibition of tumor formation. So far, reports on EP300-ZNF384 fusion gene were rare, the biological characteristics of leukemia with EP300-ZNF384 and the leukemogenesis of the fusion gene were largely unknown. The applicant established a cell line, JIH-5, with EP300-ZNF384 successfully, and got a group of fusion gene positive patients from about 300 ALL cases, the preliminary study showed that such populations have unique clinical, cytogenetic and molecular characteristics.In this sutdy, we plan to take JIH-5 cell line and EP300-ZNF384 positive patients as objects, and determine the role of EP300-ZNF384 fusion protein in leukemogenesis through multiple techniques in vivo and in vitro, such as gene transfection, Ion torrent, animal models, and so on. This study will provide more details on the pathogenesis of EP300-ZNF384 fusion protein in leukemia.

EP300调控多种基因活性，ZNF384隶属于锌指蛋白基因家族，这两种基因均与细胞的生长、分化、胚胎形成和肿瘤发生有关。目前涉及EP300-ZNF384融合基因的报道较为罕见，该类白血病的生物学特征以及EP300-ZNF384融合蛋白的致白血病机制尚未明确。申请人建立了一株携带EP300-ZNF384的细胞系JIH-5，并自300余例ALL患者中，筛选到一组伴有EP300-ZNF384的病例，初步研究显示该类患者具有独特的临床、遗传学和分子生物学特征。本课题拟以JIH-5细胞系和该组患者为研究对象，采用基因表达谱芯片、Ion torrent、RQ-PCR、基因转染、模式生物等手段，从体内外两方面揭示该类白血病的临床和生物学特征以及EP300-ZNF384融合蛋白致白血病的分子机理和靶向调控途径。

EP300调控多种基因活性，ZNF384隶属于锌指蛋白基因家族，这两种基因均与细胞的生长、分化、胚胎形成和肿瘤发生有关。课题组通过多种试验得出以下结论：1）EP300-ZNF384融合基因发病率低，主要分布于B-ALL患者。2）携带EP300-ZNF384融合基因的患者常伴有其他多种突变，包括TBL1XR1、FLT3、ATRX、ETV6、KMT2C、NRAS、SETD2、KRAS、EZH2、NF1、PAK3等，其中TBL1XR1和FLT3-ITD突变率最高。3）EP300-ZNF384、TCF3-ZNF384、TAF15-ZNF384融合基因对细胞增殖无明显影响，但在IL-3撤退实验中,EP300-ZNF384可以明显有降低细胞凋亡率的趋势。4）EP300-ZNF384融合基因阳性细胞系中，FLT3-ITD突变通过影响STAT5蛋白磷酸化发挥致白血病作用。5）过表达EP300-ZNF384可以明显缩短小鼠的总生存期。本研究结果为EP300-ZNF384融合基因参与了该类患者白血病发病提供了可靠的科学依据。