Epigenetic Induction of Gliomagenesis in Neural Progenitor Cells

项目摘要 胶质瘤是一种无法治愈的脑瘤，可分为不同的分子亚型。一种胶质瘤亚型 其特征是异柠檬酸脱氢酶1(IDH1)功能增益突变和CpG高甲基化 PROFILE(G-CIMP)是IDH1功能突变直接引起的。基因或启动子中的CpG甲基化抑制 基因表达，因此突变的IDH1被认为通过沉默抑癌基因而发挥其致癌作用 基因。伯恩斯坦实验室引入了新的数据，增加了CCCTC结合因子(CTCF)结合位点 (绝缘体)在IDH突变型胶质瘤甲基化位点的列表中。CTCF将基因组按拓扑划分为 相关结构域(TADS)：允许基因-增强子相互作用的隔绝邻域 TAD，同时限制外部互动。绝缘子甲基化扰乱TADS并允许异常基因- 增强子相互作用发生，驱动基因表达。在以下情况下发现了反复出现的绝缘子损耗 IDH突变型胶质瘤中的PDGFRA癌基因位点，允许远端增强子上调PDGFRA，驱动 已确诊的胶质瘤中的增殖。目前尚不清楚这种表观遗传机制是否能改变神经 祖细胞：可能是神经胶质瘤起源的细胞。 假设：鼻咽癌中PDGFRA绝缘体的破坏足以驱动过度增殖和 神经胶质瘤形成。 目的1：探讨绝缘体功能障碍对鼻咽癌细胞PDGFRA表达的影响。 目的2：评估绝缘体功能障碍对体内神经前体细胞的影响。 拟议中的研究将探索神经胶质瘤从鼻咽癌发展成胶质瘤的新机制，并将成为 首次展示了肿瘤发生的表观遗传学机制。此外，拟议的研究可以表明 用去甲基化药物(5-氮胞苷)治疗突变型IDH1胶质瘤可能是有益的。 此外，拟议的研究将建立一个忠实的胶质瘤小鼠模型，允许进行临床前试验。 活体内的治疗方法。IDH1的突变，类似于在胶质瘤中观察到的，也可以在其他肿瘤中观察到 这表明这项研究的发现也适用于其他类型的肿瘤。 培训计划和环境：拟议的研究将在马萨诸塞州的伯恩斯坦实验室进行 在表观基因组学研究方面取得重大进展的综合医院(MGH)。所有必要的 设备可以在伯恩斯坦实验室或位于麻省理工学院的研究中心获得。其从属关系为 哈佛医学院、博德研究所和麻省理工学院，我将有足够的机会参加研讨会和 在我迈向独立研究职位的过程中，研讨会将帮助我塑造我的职业生涯。作为一部分 在我的培训计划中，我还将在实验室指导学生，在当地和全国范围内展示我的研究成果，以及 申请过渡期奖项，使我能够在癌症研究领域追求独立的职业生涯。

Project Summary Gliomas are incurable brain tumors that can be classified into distinct molecular subtypes. One glioma subtype is characterized by isocitrate dehydrogenase 1 (IDH1) gain-of-function mutations and a CpG hypermethylator profile (G-CIMP) directly caused by mutant IDH1 function. CpG methylation in a gene or promoter suppresses gene expression, hence mutant IDH1 was thought to exert its oncogenic role by silencing tumor suppressor genes. The Bernstein laboratory introduced new data that added CCCTC-binding factor (CTCF) binding sites (insulators) to the list of methylated sites in IDH mutant glioma. CTCF partitions the genome into topologically associated domains (TADs): insulated neighborhoods that allow gene-enhancer interactions inside the same TAD while restricting outside interactions. Insulator methylation disrupts TADs and allows aberrant gene- enhancer interactions to take place, driving gene expression. A recurrent insulator loss was identified in the PDGFRA oncogene locus in IDH mutant glioma, allowing for a distal enhancer to upregulate PDGFRA, driving proliferation in established glioma. It is not known whether this epigenetic mechanism can transform neural progenitor cells (NPCs): the likely glioma cell of origin. Hypothesis: Disruption of the PDGFRA insulator in NPCs is sufficient to drive hyper-proliferation and gliomagenesis. Aim 1: Determine the mechanistic effects of insulator dysfunction on PDGFRA expression in NPCs. Aim 2: Assess the consequence of insulator dysfunction on NPCs in vivo. The proposed studies will explore novel mechanisms by which glioma develops from NPCs and would be the first demonstration of an epigenetic mechanism of tumor initiation. Further, the proposed studies can suggest that treatment with hypomethylating agents (5-azacytidine) may be beneficial for mutant IDH1 glioma. Additionally, the proposed studies will establish a faithful mouse model of glioma allowing for preclinical testing of therapeutics in vivo. Mutations in IDH1, similar to those observed in glioma, can be observed in other tumors suggesting that the findings from the study can be applicable to other tumor types. Training plan and environment: The proposed research will take place in the Bernstein lab at Massachusetts General Hospital (MGH) that has spearheaded major advances in epigenomics research. All the necessary equipment is available either in the Bernstein lab or at research cores located in MGH. With affiliations at Harvard Medical School, the Broad Institute, and MGH, I will have ample opportunities to attend seminars and workshops that will help me shape my career as I progress towards an independent research position. As part of my training plan, I will also mentor students in the lab, present my research both locally and nationally, and apply to transition awards allowing me to pursue an independent career in cancer research.