Investigation of tumor suppressive miR-148a in IDH mutant gliomas

项目摘要/摘要 神经胶质瘤目前仍无法通过目前可用的放疗和化疗手段治愈。 神经胶质瘤的密集分子特征揭示了丰富的分子多样性，使 希望我们可以通过翻译最有希望的目标来显著影响这种疾病 变成了个性化的治疗。这项建议通过研究肿瘤抑制直接满足了这一需求。 利用创新和强大的DNA甲基化图谱鉴定新靶点miR-148A的机制 在私家侦探的实验室里制定了策略。虽然还没有在胶质瘤中进行研究，但miRNA-148A正在成为一种 在其他癌症中抑制肿瘤的miRNA。作为抑制基因表达的非编码小RNA，miRNAs 在癌症机制中占据关键角色，并提供作为自身或基因的新兴治疗靶点 他们进行监管。对癌症组织的广泛基因组特征表明，广泛存在的 异常的DNA CpG岛甲基化，这可能与某些miRNAs的表观遗传沉默有关。 最近发现的异柠檬酸脱氢酶(IDH)突变被认为不仅提供了 继发性胶质瘤不仅是胶质瘤发生的始动事件，也是胶质瘤发生的始动事件。我们对IDHMUT胶质瘤的研究 有助于识别与IDHMUT相关的全基因组超甲基化特征--胶质瘤-CpG 岛甲基化表型(G-CIMP)，在正常组织或IDH野生型胶质瘤中不存在。这导致了 一种被广泛接受但尚未得到支持的假说，即G-CIMP在胶质瘤形成中发挥关键作用 通过沉默肿瘤抑制基因和/或参与分化的基因。因此，我们假设 IDHMUT相关DNA高甲基化可能抑制重要抑癌基因的表达 胶质瘤中的miRNAs。如我们的初步数据所示，我们使用无偏甲基化分析来识别 G-CIMP背景下的miRNA基因高甲基化，在这些候选基因中，miRNA-148A出现 不仅具有肿瘤抑制特性，而且还能直接调节DNA中的关键基因DNMT1 甲基化维持。在这个提案中，我们测试了IDHMUT导致表观遗传学的中心假设 抑制肿瘤的miR-148A的沉默和miR-148A的重新表达提供了一种新的策略 胶质瘤治疗，特别是IDHMUT亚群。这样做的目的是：1)研究分子基础 将IDH突变与miR148a下调联系起来，2)建立miR-148A下游靶基因 3)探讨miR-148A对IDHMUT胶质瘤的治疗潜力。 这些目的将结合无偏见的高分辨率甲基化简档技术来实现， 丰富的患者组织资源和多种细胞模型，包括患者来源的神经胶质瘤神经球 细胞。上述目标的实现将对小说的发展做出重大贡献 基于修复缺陷miRNAs的胶质瘤个体化治疗。

Project Summary/Abstract Gliomas presently remain incurable with currently available radiation and chemotherapeutic modalities. Intensive molecular characterization of gliomas have revealed a rich molecular diversity of aberrations that give rise to the hope that we can significantly impact this disease through translation of the most promising targets into personalized therapies. This proposal directly addresses this need by investigating the tumor suppressive mechanism of a novel target, miR-148a, identified using an innovative and powerful DNA methylation profiling strategy established in the PI's laboratory. Although not yet studied in glioma, miRNA-148a is emerging as a tumor suppressive miRNA in other cancers. As small non-coding RNAs that suppress gene expression, miRNAs occupy key roles in cancer mechanisms and provide emerging therapeutic targets as either themselves or genes they regulate. Extensive genomic characterization of cancer tissue has revealed the widespread presence of aberrant DNA CpG island methylation, which can be associated with the epigenetic silencing of some miRNAs. The recently discovered isocitrate dehydrogenase (IDH) mutation is thought not only to provide a biomarker of secondary gliomas but also represent an initiating event in gliomagenesis. Our research in IDHMUT gliomas has contributed to the recognition of an IDHMUT-associated genome-wide hypermethylation profile, glioma-CpG island methylator phenotype (G-CIMP), that is not found in normal tissue or IDH wild-type gliomas. This has led to a widely accepted but as yet unsupported hypothesis that G-CIMP occupies a pivotal role in gliomagenesis through silencing of tumor suppressive genes and/or genes involved in differentiation. Thus, we hypothesized that IDHMUT-associated DNA hypermethylation may silence the expression of important tumor-suppressive miRNAs in glioma. As shown in our preliminary data, we used unbiased methylation profiling to identify hypermethylated miRNA genes in the context of G-CIMP, and among these candidates, miRNA-148a appears not only to have tumor suppressive properties but also to directly regulate DNMT1, a key gene involved in DNA methylation maintenance. In this proposal, we test the central hypotheses that IDHMUT causes epigenetic silencing of the tumor suppressive miR-148a and that re-expression of miR-148a provides a novel strategy for glioma treatment, particularly for the IDHMUT subset. To do so, the aims are: 1) to investigate the molecular basis linking IDH mutation and miR148a downregulation, 2) to establish miR-148a downstream target genes contributing to tumor suppression, and 3) to explore the therapeutic potential of miR-148a in IDHMUT glioma. These aims will be accomplished combining an unbiased high-resolution methylation profiling technique, extensive patient tissue resources, and a variety of cell models including patient-derived glioma neurospheres cells. Accomplishment of the stated aims will have a significant contribution towards the development of novel tailored treatments for gliomas based on restoration of deficient miRNAs.