Slit1蛋白质对胶质瘤干细胞功能调控的机制研究

Glioblastoma (GBM) is the most lethal and prevalent primary malignant brain tumor with poor prognosis, despite aggressive therapy. Glioma stem cells (GSCs) play a dominant role in tumor growth, maintenance and even recurrence after current aggressive therapy through multiple mechanisms and networks. In our previous study, we found that GSC communicates with each other in a specific way (Cell Reports, 2014). Further investigation showed that Slit1, a secreted protein, significantly inhibits the maintenance of GSC. Analysis of TCGA database indicated that Slit1 level is lower in normal brain compared with GBM and significantly positively correlated with tumor grade, suggesting that Slit1 is a cancer stem cell suppressor. Base on this finding, we will keep working on the molecular mechanism of Slit1 in GSC maintenance, differentiation, invasion and GBM development by using the CRISPR/Cas9 system for stabilized expression or knockout, combining with the orthotopic model of GBM in mouse. We will further examine Slit1 expression by using GBM clinical sample and analyze the correlation between Slit1 and GBM survival. This study will identify a novel cancer stem cell regulator, and highlight the important prognostic values for Slit1 in human brain tumor pathogenesis.

胶质母细胞瘤（GBM）是人类恶性程度最高的肿瘤之一，目前尚无有效的治疗手段。胶质瘤干细胞（GSC）被认为是胶质瘤发生、发展、耐药和复发的主要原因之一。我们在前期工作中发现GSC之间存在特异的通讯方式（Cell Reports，2014），在此基础上进一步研究发现分泌蛋白质Slit1对 GSC的干性具有显著的抑制作用，数据库分析Slit1在GBM中低表达，提示Slit1有可能是GSC的特异抑制因子。基于以上线索，本项目拟进一步利用CRISPR技术进行基因的表达或敲除，并结合小鼠原位GBM模型进行体内分析，深入研究Slit1对GSC干性保持、分化调控、肿瘤浸润以及肿瘤发生的调控及其作用机制。结合临床样本检测Slit1在GBM组织中的表达、与GSC的共定位，并分析其与脑肿瘤分型及患者预后的相关性。该研究将有可能发现一个全新的肿瘤干细胞抑制基因，为针对肿瘤干细胞的临床治疗提供全新靶点和实验依据。

胶质母细胞瘤（GBM）是恶性程度最高的脑肿瘤，免疫治疗不敏感。肿瘤细胞免疫逃逸常导致肿瘤免疫治疗耐受，阐明肿瘤细胞对微环境免疫因子的抵抗机制将促进肿瘤免疫治疗的敏感性。胶质瘤干细胞（GSC）是GBM耐药、复发的关键因素，然而GSC免疫逃逸的机制并不清楚。课题原计划在研究SLIT1蛋白对GSC的调控中发现实验结果与前期的假设矛盾，因此我们说明情况并调整了研究方向。我们研究发现GSC对肿瘤微环境中干扰素抑制不敏感，提示GSC存在干扰素逃逸。我们发现干扰素信号通路核心调控基因STAT1在GSC中显著低表达，重新表达STAT1促进GSC对干扰素的敏感性，抑制肿瘤发生。进一步研究发现GSC中STAT1表达受到表观遗传调控复合体NuRD-MBD3的抑制。MBD3在GSC中特异性高表达，靶向敲低MBD3导致STAT1表达升高，重新激活STAT1信号通路，促进GSC对干扰素的响应。以此为基础的联合治疗将可能促进胶质瘤对免疫微环境易感，增强临床胶质瘤免疫治疗的效果。