胶质瘤细胞增殖过程中β-catenin/EZH2/miR-181d环路的调控机理

Functional network system mediated by aberrant signaling plays an important role in glioma development. In recent study, we have showed that β-catenin potentially regulated EZH2 expression at the transcriptional level, EZH2 silenced miR-181d expression, and miR-181d reduced β-catenin expression, further participated in glioma cell proliferation. Thus, the modulation between β-catenin and EZH2 maybe a network process including regulation, coordination and feedback. We will determine EZH2 transcription by β-catenin, miR-181d repression by EZH2 and β-catenin silencing by miR-181d, explore the inherent connection in β-catenin/EZH2/miR-181d feedback loop, and test the cell proliferation function of this feedback loop. Our study will establish the function and mechanism of β-catenin/EZH2/miR-181d feedback loop in glioma cell proliferation, and provide the reference for exploring functional network system and therapy target in glioma.

基于异常信号分子的多模式的功能网络调控体系在胶质瘤发生发展中发挥着重要的精细调控作用。我们前期研究发现：β-catenin潜在转录调控EZH2，EZH2能下调miR-181d表达，而miR-181d又能下调β-catenin表达，三者构成一个环路，共同调节胶质瘤细胞增殖。为此我们提出假说：β-catenin与EZH2两者间的调控很可能是调节、协同、反馈并存的多重网络化过程。课题拟证实β-catenin对EZH2的转录调控关系，明确EZH2对miR-181d的基因沉默关系，验证miR-181d对β-catenin靶向调控关系，探索β-catenin/EZH2/miR-181d环路间内在联系及其对胶质瘤细胞增殖的影响。课题可确立胶质瘤细胞增殖过程中β-catenin/EZH2/miR-181d环路的功能与机制，为胶质瘤的功能网络调控体系研究提供有益补充，为寻找胶质瘤治疗靶点提供理论依据。

胶质瘤中EZH2与β-catenin信号两者间的调控很可能是调节、协同、反馈并存的多重网络化过程。本研究发现EZH2的表达与胶质瘤级别正相关，是胶质母细胞瘤患者的独立预后因子。下调EZH2表达抑制胶质瘤细胞体内外生长。EZH2与β-catenin/TCF4和STAT3之间存在相互调控：敲低EZH2表达能有效抑制β-catenin和STAT3的表达；反之抑制β-catenin/TCF4和STAT3，导致EZH2的表达明显下降。miRNA芯片数据分析发现EZH2可沉默一系列miRNA，靶向调控β-catenin表达，进而影响胶质瘤细胞糖代谢。发现EZH2小分子抑制剂GSK343可抑制H3K27甲基化水平，降低PRC2核心蛋白水平并阻碍EZH2与H3结合，进而抑制胶质瘤恶性表型。进一步识别发现胶质瘤中EZH2特征性miRNA，其中抑癌miRNA miR-524-5p 和 miR-324-5p可通过靶向调控EZH2表达来抑制胶质瘤细胞生长。本项目 引入miRNA作为研究桥梁，着眼于明确胶质瘤中的EZH2与β-catenin间调控、协同、反馈并存的多重网络化作用模式；以EZH2为突破口，从胶质瘤级别预后判断、机理研究到药物筛选，体现基础临床转化思想；为现有的胶质瘤发生发展机制提供有益补充，为寻找胶质瘤治疗靶点提供理论依据，具有重大实际应用价值和深刻的理论意义。