Investigating L-2-hydroxyglutarate in normal hematopoiesis and leukemogenesis

项目总结/摘要 异柠檬酸脱氢酶（IDH）酶的体细胞突变有助于急性胰腺炎的发病机制。 通过产生“癌代谢物”D-2-羟基戊二酸， （D-2HG）。D-2 HG通过抑制α-酮戊二酸（αKG）依赖性 调节染色质结构和基因表达的酶。突变型IDH的小分子抑制剂 酶正在成为AML患者有前途的新疗法，但其疗效仍然有限， IDH突变患者的子集。2 HG是可以以D-或L-构型存在的手性分子， 对映体。生化分析表明，L-2 HG比D-2 HG更有效地作为一种抑制剂， α KG依赖的染色质修饰酶，但L-2 HG的生物来源和活性都很差 明白本提案中提出的初步数据描述了一种以前未知的代谢途径 其中在氧限制条件下（a.k.a.缺氧）时，细胞通过 乳酸脱氢酶对αKG的混杂酶促还原。L-2 HG稳定缺氧诱导因子 1α（HIF 1 α）并增加未分化/干细胞状态特征性的抑制性组蛋白修饰。 低氧诱导的L-2 HG通路在原代胚胎干细胞和造血干细胞中是活跃的 (ESCs/HSC）和白血病细胞，并且增加L-2 HG水平的实验操作阻断了这些细胞的增殖。 原代HSC和ESC的分化。正常的造血干细胞和白血病细胞存在于 对骨髓缺氧区域的影响因此，L-2 HG可能代表了一种分子机制， 低氧小生境促进和维持正常造血干细胞和白血病的未成熟状态 干/祖细胞。这一假设将通过（1）使用体外系统来阐明 L-2 HG对造血细胞基因表达、表观遗传修饰和分化的影响，（2） 采用体内小鼠模型来确定L-2 HG是否影响正常或恶性造血，以及（3） 利用患者样品确定L-2 HG代谢失调是否是人白血病的特征。的 所提出的研究将扩展策略的手段以治疗癌症中的2 HG， 特别是对于缺乏IDH突变的大群患者。申请人Andrew Intlekeln博士， 助理出席与淋巴瘤服务纪念斯隆凯特琳癌症中心（MSKCC）， 概述了一个5年的职业计划，建立在他的研究背景研究细胞的分子机制 分化和他在肿瘤学和恶性血液学的临床培训。Intlekendy博士将主持 在克雷格汤普森博士的指导下进行了一项研究，汤普森博士是一位国际公认的专家， 癌症代谢与良好的记录培训成功的内科医生科学家。MSKCC提供 理想的机构环境，为博士Intleklane着手拟议的研究计划，并过渡到 作为一个独立的学术研究者，拥有自己的实验室和R 01资金。

PROJECT SUMMARY/ABSTRACT Somatic mutations in the isocitrate dehydrogenase (IDH) enzymes contribute to the pathogenesis of acute myeloid leukemia (AML) and other malignancies via production of the `oncometabolite' D-2-hydroxyglutarate (D-2HG). D-2HG blocks differentiation of malignant cells by inhibiting α-ketoglutarate (αKG)-dependent enzymes that regulate chromatin structure and gene expression. Small molecule inhibitors of mutant IDH enzymes are emerging as promising new therapies for patients with AML, but their efficacy remains limited to the subset of patients with IDH mutations. 2HG is a chiral molecule that can exist in either the D- or L- enantiomer. Biochemical assays show that L-2HG functions much more potently than D-2HG as an inhibitor of αKG-dependent chromatin-modifying enzymes, but biological sources and activities of L-2HG are poorly understood. Preliminary data presented in this proposal describe a previously unknown metabolic pathway where under conditions of oxygen limitation (a.k.a. hypoxia), cells potently and selectively produce L-2HG via promiscuous enzymatic reduction of αKG by lactate dehydrogenase. L-2HG stabilizes hypoxia-inducible factor 1α (HIF1α) and increases repressive histone modifications characteristic of the undifferentiated/stem cell state. The hypoxia-induced L-2HG pathway is active in primary embryonic and hematopoietic stem cells (ESCs/HSCs) and leukemia cells, and experimental manipulations that increase L-2HG levels block the differentiation of primary HSCs and ESCs. Normal blood stem cells and leukemia cells reside in and depend on hypoxic regions of the bone marrow. Thus, L-2HG might represent a molecular mechanism whereby hypoxic niches promote and maintain the immature state of normal blood stem cells and leukemia stem/progenitor cells. This hypothesis will be rigorously tested by (1) using in vitro systems to elucidate the effects of L-2HG on hematopoietic cell gene expression, epigenetic modifications, and differentiation, (2) employing in vivo mouse models to determine if L-2HG influences normal or malignant hematopoiesis, and (3) utilizing patient samples to determine if deregulated L-2HG metabolism is a feature of human leukemia. The proposed investigations will expand the armamentarium of strategies to therapeutically target 2HG in cancer, particularly for the large cohort of patients who lack IDH mutations. The applicant, Dr. Andrew Intlekofer, an Assistant Attending with the Lymphoma Service at Memorial Sloan Kettering Cancer Center (MSKCC), has outlined a 5-year career plan that builds upon his research background studying molecular mechanisms of cell differentiation and his clinical training in oncology and malignant hematology. Dr. Intlekofer will conduct the proposed research under the mentorship of Dr. Craig Thompson, an internationally recognized expert in cancer metabolism with a strong track record of training successful physician scientists. MSKCC provides the ideal institutional environment for Dr. Intlekofer to embark on the proposed research program and transition to a position as an independent academic investigator with his own laboratory and R01 funding.