Genotypic Interactions in Brain Cancer Heterogeneity

脑癌异质性中的基因型相互作用

• 批准号: 10375989
• 负责人: Frank Furnari
• 金额: $ 17.75万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2023-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10375989
• 关键词: Genotypic; Interactions; Brain; Cancer; Heterogeneity

Project Summary Minimal improvement in the 12-15 month average survival of patients with glioblastoma multiforme (GBM) has been achieved despite decades of advances in neurosurgery and radiation therapy, many clinical trials for novel therapeutics, and increased understanding of the driving molecular mechanisms. A central issue that confounds successful treatment is the heterogeneous nature of this aggressive tumor. This heterogeneity presents phenotypically as mixed cytological subtypes, genotypically as mutations and gene amplifications, and transcriptionally as regional differences in gene expression. As a result, multiple and spatially distinct heterotypic populations exist within a single GBM, making any lesion- or pathway-specific therapy less effective. While considerable effort has been placed on understanding cell intrinsic mechanisms conferring therapeutic resistance, much less is known about the interactions between heterogeneous tumor cells within these neoplasms that contribute to the recalcitrant nature of this cancer. In GBM, amplification of the epidermal growth factor receptor, a hallmark mutation present in 60% of cases, often occurs in a heterogeneous manner and is frequently associated with structural alterations. The most common of these alterations, EGFRvIII, (also known as ∆EGFR) results in a constitutively active mutant receptor with tumor enhancing capability. This ability is lacking from amplified wtEGFR despite its more pervasive tumor expression. By modeling this type of genetic heterogeneity in vivo, we have determined that an IL-6 paracrine signaling mechanism driven by EGFRvIII activity can not only recruit wtEGFR-expressing cells into accelerated proliferation, but also promote EGFR-targeted therapeutic resistance through activation of a pro-survival inflammatory NF-κB/BRD4 signaling axis. Given the central role of NF-κB/BRD4 in the remodeling of chromatin super enhancers we postulate that EGFRvIII/wtEGFR sub-population interactions not only enhance aggressive tumor growth, but also prompt the synchronization of aspects of gene expression in these heterotypic cells through shared enhancer remodeling. The overall goal of this renewal project is to dissect and target the mechanisms whereby GBM EGFR/EGFRvIII heterogeneity drives therapeutic resistance through orchestration of NF-κB/BRD4-mediated remodeling of the epigenetic landscape. The following lines of experimentation will be carried out: 1) genome editing to create a drug-selective BRD4 allele for mechanistic chemical biology studies; 2) use of this modified BRD4 allele as a tool for chromatin structure and functional analysis of the cytokine-stimulated NF-κB/BRD4 enhancer landscape in heterotypic and subpopulation-ablated gliomas; 3) genetic and pharmacological inhibition of identified NF-κB/BRD4-mediated genetic or epigenetic vulnerabilities shared among EGFR and EGFRvIII heterotypic cells to enhance therapeutic efficacy.

项目摘要 胶质母细胞瘤多形（GBM）患者的12-15个月平均生存率的最小改善已有 尽管神经外科和放射疗法有数十年的进步，但我们还是成功的，许多临床试验 新的疗法，并增加对驱动分子机制的理解。一个中心问题 混淆成功治疗是这种侵略性肿瘤的异质性质。 表现出表面形式作为混合细胞学亚型，基因型作为突变和基因扩增， 在基因表达中作为区域差异在转录上。结果，多个和空间不同 异型种群存在于单个GBM中，使任何病变或途径特异性疗法降低 有效的。虽然已经为了解细胞固有机制会议而付出了巨大的努力 治疗性抗性，对异质肿瘤细胞之间的相互作用的了解少得多 这些肿瘤有助于这种癌症的顽固性。在GBM中，放大 表皮生长因子受体是60％的病例中存在的标志性突变，通常发生在A 异质方式，经常与结构改变有关。其中最常见的 EGFRVIII的改变（也称为∆EGFR）导致具有肿瘤的组成性活性突变体受体 增强功能。该功能由于放大的WTEGFR目的地缺乏其更普遍的肿瘤 表达。通过在体内建模这种类型的遗传异质性，我们确定了IL-6旁分泌 由EGFRVIII活性驱动的信号传导机制不仅可以募集表达WTEGFR的细胞加速 增殖，但也通过激活促生物存在来促进EGFR靶向的治疗性 炎症NF-κB/BRD4信号轴。鉴于NF-κB/BRD4在重塑中的核心作用 染色质超级增强剂我们假设EGFRVIII/WTEGFR子群相互作用不仅增强 侵略性肿瘤生长，但也促使基因表达方面的同步 通过共享增强剂重塑的异型细胞。 该更新项目的总体目标是剖析和针对GBM EGFR/EGFRVIII的机制 异质性通过编排NF-κB/BRD4介导的重塑，驱动热抗性 表观遗传景观。将进行以下实验行：1）基因组编辑以创建一个 用于机械化学生物学研究的药物选择性BRD4等位基因； 2）将此修改后的BRD4等位基因用作 用于细胞因子刺激的NF-κB/BRD4增强剂的染色质结构和功能分析的工具 异型和亚群的胶质瘤中的景观； 3）遗传和药物抑制 鉴定出EGFR和EGFRVIII共享的NF-κB/BRD4介导的遗传或表观遗传脆弱性 异型细胞增强治疗效率。