神经胶质成熟因子-β介导胶质瘤干细胞向血管内皮细胞转分化的作用及机制研究

In recent years, researches have shown that endothelial transdifferentiation of glioma stem cells is an important means for glioma neovasculogenesis, but the underling molecular mechanisms have not yet been elucidated. The reciprocal coordination exists between neurogenesis and angiogenesis, sharing some common regulators. Thus, our previous study was aimed at glia maturation factor-β (GMF-β), and found that GMF-β can enhance in vitro tubulogenesis and in vivo vasculogenesis of glioma cells. Bioinformatics analysis showed that GMF-β is a potential target gene of HIF-1, moreover, it has been reported that GMF-β can activate p38 kinase pathway, which can further activate cAMP response element binding protein (CREB), a potential regulator for endothelial differentiation. So we hypothesize that GMF-β plays an important role in inducing glioma stem cells to transdifferentiate into vascular endothelial cells by HIF-1/GMF-β/p38/CREB signaling pathway. This project is intended to confirm the hypothesis by implementing a series of in vitro and in vivo experiments, using flow cytometry, gene knockdown and overexpression, orthotopic xenotransplant model, eGFP reporter gene and other methods. Findings from this study maybe a breakthrough in the exploration of the mechanism of glioma-associated neovascularization, and may provide a specific molecular target for anti-angiogenic therapy in glioma.

近年来研究发现，胶质瘤干细胞转分化为血管内皮细胞是胶质瘤血管新生的重要方式之一，但其分子机制尚未阐明。神经分化和血管生成之间可通过某些调控因子协同促进，我们前期研究探讨并发现，神经胶质成熟因子-β（GMF-β）能增强胶质瘤细胞的体外成管能力和体内血管发生活性。生物信息学分析表明GMF-β是HIF-1的潜在靶基因，文献报道GMF-β能激活p38激酶通路，而后者能活化具内皮分化调控潜能的cAMP反应元件结合蛋白（CREB）。故我们推测： GMF-β可能通过参与形成HIF-1/GMF-β/p38/CREB信号通路，介导胶质瘤干细胞的内皮转分化。本课题拟采用流式细胞术、基因敲低和过表达、异种原位移植瘤、eGFP报告基因等多种技术，实施一系列体内外实验以证实该假设。本研究结果有望成为胶质瘤新生血管形成机制研究的一个突破点，并可望为胶质瘤抗血管生成治疗提供一个特异性的分子靶点。

近年来研究发现，胶质瘤干细胞转分化为血管内皮细胞是胶质瘤血管新生的重要方式之一，但其分子机制尚未阐明。本课题组从神经分化和血管发生之间协同促进的角度，探讨神经胶质成熟因子-β（GMF-β）促进胶质瘤干细胞向血管内皮细胞转分化的作用及机制。本研究中，我们采用体外血管生成、诱导内皮转分化、双荧光素酶报告基因、异种原位移植瘤等多种技术，通过一系列体内外实验，明确了GMF-β促进胶质瘤血管新生的关键作用及规律；我们进一步阐明了HIF-1α/GMF-β信号通路在调控胶质瘤干细胞血管发生活性中的重要作用：①缺氧诱导因子-1α（HIF-1α）与多重促血管生长因子（VEGF/bFGF/EGF）相比，更显著地上调胶质母细胞瘤干细胞中GMF-β表达水平，且更显著地促进血管拟态形成或发生血管内皮样分化（P<0.001；P<0.01）；②我们验证了HIF-1α与GMF-β基因启动子结合，从而增强GMF-β的转录表达。本研究首次揭示了GMF-β促进胶质瘤血管新生的重要作用及关键信号通路，有助于更新对该因子的传统认识、有助于深入认识胶质瘤血管化的根本机制。GMF-β有望成为一个新型的胶质瘤预后标记和抗血管治疗新靶点。