“转录因子Gli2/miR-124/AURKA”信号轴调控神经胶质细胞瘤形成的分子机制

Multiple lines of evidence implicate that aberrant activation of Hedgehog (Hh) signaling is involved in a variety of human cancers. However, the molecular mechanisms underlying how cancer cells respond to Hh inhibition remain to be elucidated. Recently, we found that inhibition of the Gli can reduce cell proliferation and colony formation in human glioma cancer cells. In addition, many kinds of microRNAs (miR-124) expression and cell cycle related genes (AURKA) levels are also changed in glioma cancer cells while blocked the Hh signaling pathway. Based on the results of bioformatics analysis, we presumed that microRNAs regulated by Gli, may have a pivotal role in the aberrant activation of Hh sinaling pathwey, Hh signaling network may influence proliferation of glioma cells through Gli2/miR-124/AURKA signaling axis. This study aimed at investigating the role of Hh-Gli regulated microRNA networks in tumorigenesis by means of bioinformatics, molecular biology, cell biology, etc. We will elucidate the molecular mechanism of Gli-miRNA networks in malignant proliferation of glioma from the four levels of molecular, cellular, animal model and clinical specimens. Completion of this study will enrich the signal process of Hh-Glisignaling network, reveal the relationship of the Hh-Gli-miRNAs signal axis with human glioma and indicate the potential for the Gli-miRNA networks in dignosis and treatment of human glioma.

Hedgehog(Hh)信号通路在神经胶质瘤中异常活化，但通路异常活化介导细胞恶性增殖的机制有待明晰。我们发现:阻断Hh通路关键节点转录因子Gli2抑制神经胶质瘤细胞增殖及克隆形成能力；抑制Hh通路后神经胶质瘤细胞中多种miRNAs(如miR-124)表达增加，同时细胞周期相关基因(如AURKA)表达减少。基于生物信息学分析，我们推测：受Gli2调控的miRNAs可能介导Hh通路异常活化过程；Hh通路通过Gli2/miR-124/AURKA信号轴调控细胞增殖，影响神经胶质瘤生长。本项目以Gli2为研究重点，采用生物信息学、分子生物学、细胞生物学等多种手段发掘受Gli2调控的miRNAs及其新靶基因，研究其调控模式；从分子、细胞及整体三个层面阐明Hh通路通过Gli2/miR-124/AURKA信号轴调控肿瘤细胞增殖，影响神经胶质瘤生长的分子机制，为寻找神经胶质瘤诊断与治疗新靶点提供理论依据。

Hedgehog（Hh）信号通路在胚胎发育中起重要作用。已有研究报道Hh信号通路在胶质瘤中异常激活，但其介导恶性细胞增殖的机制尚不清楚。转录因子 Gli2 (Glioma-associated oncogene transcription factors, Gli) 位于Hh信号通路级联传导的末端，是该通路的关键调控因子。本研究主要探讨Gli2在胶质瘤细胞增殖调控中的分子机制。首先, 我们发现阻断Hh通路关键节点转录因子Gli2抑制神经胶质瘤细胞增殖及克隆形成能力；同时神经胶质瘤细胞中多种miRNAs (例如: miR-124 等) 表达增加，细胞周期相关基因 (例如: AURKA等) 表达减少。通过进一步的研究，我们发现: (1) 转录因子Gli2的抑制上调了miR-124在胶质瘤细胞中的表达; (2) Gli2通过结合miR-124的转录起始位点负调控miR-124的表达; (3) miR-124 通过靶向 AURKA 3́ -UTR，负性调控 AURKA 表达。此外，我们证实Hh信号调节Gli2/ miR-124/AURKA信号轴，调控胶质瘤细胞增殖和克隆形成，并通过临床队列研究了Gli2/miR-124/AURKA信号轴的变化与胶质瘤临床预后的关系。 通过本研究, 我们阐明了一个新的调控机制, 即: Hh 信号通路通过“Gli2/miR-124/AURKA”信号轴调控肿瘤细胞增殖和神经胶质细胞瘤生长。在此基础上，我们基于TCGA数据库的相关数据构建了一种新颖方便的肿瘤预后预测模型 (nomogram模型)，分析了胶质细胞瘤患者的生存概率和预后。本研究项目的实施在理论上有助于拓展Hh信号通路的信号过程，在实践上将有助于阐明Hh信号通路在神经胶质细胞瘤发生发展过程中的作用和分子机制，为神经胶质细胞瘤的诊断和治疗提供新的靶点，推动肿瘤的转化医学研究。