Identifying genetic vulnerabilities in KIAA1549-BRAF mutant pediatric low-grade gliomas

识别 KIAA1549-BRAF 突变儿童低级别神经胶质瘤的遗传脆弱性

• 批准号: 10752212
• 负责人: Sean Alexander Misek
• 金额: $ 7.18万
• 依托单位: BROAD INSTITUTE, INC.
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10752212
• 关键词: Affect; BRAF gene; Binding; Brain; CRISPR screen; Cell membrane; Cells; Childhood; Chronic; Clinical; Complex; DNA Sequence Alteration; Dependence; Development; Dose; Dose Limiting; Essential Genes; Event; GIT2 gene; Genes; Genetic Predisposition to Disease; Genome; Glioma; Goals; Human; Integral Membrane Protein; Knowledge; Length; MAP Kinase Gene; Mediating; Membrane; Modeling; Mutation; N-terminal; Oncogenes; Oncogenic; Pathway interactions; Patients; Plasma Enhancement; Post-Translational Protein Processing; Proteins; Proteome; Resistance; Signal Transduction; Site; Testing; Therapeutic; Toxic effect; Transmembrane Domain; Withholding Treatment; cell growth; cofactor; extracellular; genome-wide; inhibitor; loss of function; member; mutant; new therapeutic target; novel therapeutics; prevent; protein-O-mannosyltransferase 1; protein-O-mannosyltransferase 2; relapse prevention; therapeutic target; tumor

Project Summary: Pediatric low-grade gliomas (pLGGs) typically harbor only a single oncogenic driver event which almost universally result in MAPK pathway activation. The most frequent of these alterations is a rearrangement that fuses the C-terminus of BRAF to the large transmembrane protein KIAA1549. Many patients whose tumors harbor this fusion respond to BRAF inhibitors, but challenges remain in extending clinical benefit to all patients. A key challenge is that patients require chronic treatment with these inhibitors throughout childhood because tumors often rebound upon cessation of treatment. These inhibitors are associated with significant dose-limiting toxicity issues, likely because the MAPK pathway is essential for brain development. These observations suggest that we need to identify new therapeutic targets for pLGG. The two core members of the POMT complex and two complex cofactors emerged as the top four dependencies in a genome-scale loss of function CRISPR/Cas9 screen. This dependency was specific for cells harboring the KIAA1549-BRAF fusion and were not dependencies in cells expressing BRAFV600E. The POMT complex is necessary for O-mannosylation of secreted and transmembrane proteins. This is striking because across all proteins in the human proteome, KIAA1549 one of the proteins most affected by this post-translational modification. It was originally hypothesized that the KIAA1549-BRAF fusion activates BRAF by truncating its negative regulatory domain, but this observation suggests that the KIAA1549 portion of the fusion may also be necessary for activating BRAF. The primary goals of this proposal are to understand why the POMT complex is a vulnerability in KIAA1549- BRAF mutant cells, and to understand how the KIAA1549 portion of KIAA1549-BRAF regulates the activity of the fusion. In Aim 1 I will test the hypothesis that POMT complex activity is necessary for the survival of KIAA1549-BRAF-dependent cells. In Aim 2 I will test the hypothesis that the POMT complex is required for O- mannosylation of KIAA1549-BRAF, and that O-mannosylation of KIAA1549-BRAF is necessary for oncogenic signaling. In Aim 3 I will test the hypothesis that the KIAA1549 portion of the KIAA1549-BRAF fusion tethers BRAF to the plasma membrane and enhances its ability to activate the MAPK pathway.

项目摘要： 小儿低级神经胶质瘤（PLGGS）通常只有一个几乎一个致癌驱动器事件 普遍导致MAPK途径激活。这些改动中最常见的是一个重排 将BRAF的C末端融合到大型跨膜蛋白KIAA1549。许多肿瘤的患者 这种融合对BRAF抑制剂有反应，但挑战仍在扩大所有患者的临床益处。 一个关键挑战是患者在整个儿童期需要对这些抑制剂进行长期治疗，因为 肿瘤通常在停止治疗后反弹。这些抑制剂与明显的剂量限制有关 毒性问题，可能是因为MAPK途径对于大脑发育至关重要。这些观察表明 我们需要确定PLGG的新治疗靶标。 POMT复合物的两个核心成员和两个复合辅助因子成为前四个依赖性 在基因组规模的功能丧失中，CRISPR/CAS9屏幕。这种依赖性是针对带有的细胞 KIAA1549-BRAF融合，不是表达BRAFV600E的细胞中的依赖性。 POMT复合物是 分泌和跨膜蛋白的O-甘露糖基化所必需的。这是令人惊讶的，因为 人类蛋白质组中的蛋白质，KIAA1549是最受此后翻译影响的蛋白质之一 修改。最初假设KIAA1549-BRAF融合通过将其截断激活BRAF 负调节域，但该观察结果表明融合的KIAA1549部分也可能是 激活BRAF所必需的。 该提案的主要目标是了解为什么POMT综合体是KIAA1549-的脆弱性。 Braf突变细胞，并了解KIAA1549 KIAA1549-BRAF的部分如何调节 融合。在AIM 1中，我将检验以下假设：POMT复合活动对于生存是必要的 KIAA1549-BRAF依赖性细胞。在AIM 2中，我将检验以下假设：O-需要POMT复合物。 KIAA1549-BRAF的甘露糖基化以及KIAA1549-BRAF的O-甘露糖基化对于致癌是必要的 信号。在AIM 3中，我将检验以下假设：KIAA1549 KIAA1549-BRAF融合系的部分 BRAF到质膜并增强其激活MAPK途径的能力。