Molecular Pathogenesis of Acute Myeloid Leukemia

急性髓系白血病的分子发病机制

• 批准号: 9126480
• 负责人: TIMOTHY J. LEY
• 金额: $ 91.5万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-13 至 2022-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9126480
• 关键词: Acute Myelocytic Leukemia; Binding; Cell physiology; Cells; ChIP-seq; Chromatin; DNA; DNA Methylation; Data; Development; Disease; Disease model; Dominant-Negative Mutation; Educational process of instructing; Epigenetic Process; Event; FLT3 gene; Genes; Genomics; Goals; Health; Hematopoietic; Hematopoietic Neoplasms; Histones; Lead; Leukemic Cell; Modeling; Molecular; Mutation; Oncogenes; Pathogenesis; Pathway interactions; Patients; Population; Proteins; Proteomics; RARA gene; Small RNA; Stem cells; Techniques; Therapeutic; Transgenic Mice; Work; bisulfite sequencing; genome sequencing; histone modification; human embryonic stem cell; inhibitor/antagonist; mutant; novel strategies; novel therapeutics; stem; targeted treatment; therapeutic target; transcriptome sequencing; tumor; whole genome

 DESCRIPTION (provided by applicant): In this proposal, we will attempt to determine the precise molecular mechanisms by which acute myeloid leukemia (AML)-initiating mutations act, and to exploit these mechanisms therapeutically. The vast majority of patients who develop AML still die from their disease. New therapies that are more efficacious and less toxic are urgently needed. Recent AML genome sequencing studies have taught us that virtually all AML tumors are clonally heterogeneous. Each tumor originates from a founding clone that was created by an initiating mutation that allowed a single hematopoietic stem/progenitor cell (HSPC) to achieve a clonal advantage. This `preleukemic' clone acquires additional, cooperating mutations that lead to the development of a founding clone, and clinically apparent AML. Subclones arise from the founding clone, or can evolve from other subclones. Regardless, all subclones contain the founding clone mutations. Although cooperating mutations are often attractive for targeted therapies (e.g. FLT3 and/or IDH1/2 inhibitors), they are sometimes found in subclones (i.e. they are only in a fraction of the total leukemic cell population); therapeutic targeting of subclones cannot be expected to be curative. The central hypothesis of this work is that a complete understanding of the consequences of initiating mutations is required to fully understand AML pathogenesis. We also hypothesize that therapeutic approaches directed against initiating mutations are the most likely to provide long-term benefit for AML patients. We will fully characterize two common, well-validated AML-initiating mutations (PML-RARA and DNMT3A R882H) that are both associated with profound epigenetic alterations in hematopoietic cells. We will utilize state-of-the-art techniques (including comprehensive, strand-specific RNA-seq of large and small RNAs, whole genome bisulfite sequencing, chromatin accessibility studies, and ChIP-seq studies for oncogene binding and histone modifications) to pinpoint the key genomic targets of these initiating mutations, and unbiased proteomic techniques to comprehensively identify proteins that interact specifically with the mutant proteins. We will integrate these data to identify genes, RNAs, loci, and pathways that are altered by the initiating mutations, and develop new hypotheses regarding mechanisms that may be relevant for AML pathogenesis. We will model AML-initiating mutations and downstream pathways both in human embryonic stem cells, and in transgenic mice expressing PML-RARA or DNMT3A R882H, to fully explore the contributions of pathways (e.g. DNA methylation and/or histone modifiers) and/or cooperating mutations that may be critical for their actions. As a translational goal of thi work, we will attempt to develop a novel drug that will inhibit the action of the mutant DNMT3A R882H protein, which acts as a dominant negative inhibitor of WT DNMT3A, thereby suppressing de novo DNA methylation in HSPCs. This mutation causes in focal, canonical, DNA hypomethylation, an event that may be reversed by an effective inhibitor, which may restore normal HSPC function.

 描述（由申请人提供）：在本提案中，我们将尝试确定急性髓性白血病（AML）引发突变起作用的精确分子机制，并在治疗上利用这些机制。绝大多数患有 AML 的患者仍然死于疾病。迫切需要更有效且毒性更小的新疗法。最近的 AML 基因组测序研究告诉我们，几乎所有 AML 肿瘤都具有克隆异质性。每个肿瘤都源自一个初始克隆，该克隆是通过起始突变创建的，该突变允许单个造血干/祖细胞 (HSPC) 获得克隆优势。这种“白血病前期”克隆获得了额外的协同突变，从而导致了创始克隆和临床上明显的 AML 的发展。亚克隆源自创始克隆，或者可以从其他亚克隆进化而来。无论如何，所有亚克隆都包含创始克隆突变。尽管协同突变对于靶向治疗（例如 FLT3 和/或 IDH1/2 抑制剂）通常很有吸引力，但有时会在亚克隆中发现它们（即它们仅占白血病细胞总数的一小部分）；亚克隆的治疗靶向不能预期具有治愈作用。这项工作的中心假设是，要充分了解 AML 发病机制，需要完全了解起始突变的后果。我们还假设针对起始突变的治疗方法最有可能为 AML 患者提供长期益处。我们将全面描述两种常见的、经过充分验证的 AML 起始突变（PML-RARA 和 DNMT3A R882H），它们都与造血细胞的深刻表观遗传改变相关。我们将利用最先进的技术（包括大RNA和小RNA的综合链特异性RNA-seq、全基因组亚硫酸氢盐测序、染色质可及性研究以及癌基因结合和组蛋白修饰的ChIP-seq研究）来查明这些起始突变的关键基因组靶标，并利用公正的蛋白质组学技术来全面鉴定与 突变蛋白。我们将整合这些数据来识别因起始基因而改变的基因、RNA、基因座和通路。 突变，并就可能与 AML 发病机制相关的机制提出新的假设。我们将在人类胚胎干细胞和表达 PML-RARA 或 DNMT3A R882H 的转基因小鼠中模拟 AML 起始突变和下游途径，以充分探索可能对其作用至关重要的途径（例如 DNA 甲基化和/或组蛋白修饰剂）和/或协同突变的贡献。作为这项工作的转化目标，我们将尝试开发一种新的药物来抑制突变型 DNMT3A R882H 蛋白的作用，该蛋白作为 WT DNMT3A 的显性失活抑制剂，从而抑制 HSPC 中的从头 DNA 甲基化。这种突变会导致局部、典型的 DNA 低甲基化，这一事件可以通过有效的抑制剂逆转，从而恢复正常的 HSPC 功能。