The Role of DLST in Leukemogenesis

项目摘要 尽管治疗方法有所改进，但由于耐药性，白血病相关死亡率仍然很高， 疾病复发。代谢重编程是癌症的一个标志，代表了一个令人兴奋的新领域， 靶向治疗因此，鉴定负责代谢重编程的关键酶， 阐明其在治疗抵抗性白血病细胞中的作用机制可能导致新的治疗方法， 针对这些癌细胞独特的代谢依赖性的策略。我们最近报道说， 二氢硫辛酰胺S-琥珀酰转移酶（DLST）在MYC-2中作为一种关键的代谢“癌必需”酶。 导致白血病MYC依赖性T-急性淋巴细胞白血病（T-ALL）细胞重编程代谢 通过稳定DLST蛋白，并在很大程度上依赖于其升高的水平来增殖和存活。杂合 斑马鱼dlst缺失不会损害发育，但会显著延迟MYC诱导的T-ALL的发作 类似于预后不良的人类疾病的主要亚型。DLST是一种转移酶 三羧酸（TCA）循环，并介导α-酮戊二酸（α-KG）转化为琥珀酰辅酶A。α-KG是 一种关键的循环中间体，同时作为α-KG依赖性 双加氧酶（α-KGDO，例如，脱甲基酶），从而将细胞代谢与表观遗传控制联系起来。 cell.我们假设：DLST蛋白稳定化加速α-KG转化，增强TCA 周期功能，并抑制α-KGDO活性，从而促进白血病细胞增殖， 生存在本申请的目的1中，我们将应用遗传、药理学和生物化学方法， 确定DLST在MYC过表达T-ALL细胞中稳定的机制，并鉴定新的 DLST相互作用物，包括其E3连接酶。然后将利用斑马鱼T-ALL模型来定义 T-ALL发病机制中的关键DLST调节因子/相互作用因子。在目标2中，我们将联合收割机结合体内分析， 斑马鱼模型和人类T-ALL细胞，以确定与 DLST失活，以及在T-ALL发病机制中由DLST调节的关键α-KGDO的功能特征。 在目标3中，我们将研究DLST在复发/难治性T-ALL中的靶向性和代偿途径 通过使用我们新鉴定的DLST抑制剂和体内动物模型， 异种移植该应用的创新之处在于对DLST作为一种新型“致癌必需”酶的研究 在生理相关的体内斑马鱼中调节细胞的代谢和表观遗传状态 系统事实上，这一创新系统使我们能够鉴定MYC和AMP活化蛋白激酶， DLST和异柠檬酸脱氢酶2作为其补偿基因的调节剂。这项研究在 它将加深我们对白血病发病机制和癌症代谢的理解， MYC依赖性白血病细胞中的代谢-表观遗传联系，其长期目标是开发 针对癌细胞中DLST介导途径的新治疗策略。

PROJECT SUMMARY Despite treatment improvements, leukemia-associated mortality is still high owing to drug resistance and disease relapse. Metabolic reprogramming is a hallmark of cancer, and represents an exciting new area of targeted therapy. Therefore, identification of the key enzyme responsible for metabolic reprogramming and elucidation of its mechanisms of action in treatment-resistant leukemic cells could lead to novel therapeutic strategies against the unique metabolic dependence of these cancer cells. We recently reported that dihydrolipoamide S-succinyltransferase (DLST) serves as a critical metabolic “oncorequisite” enzyme in MYC- driven leukemogenesis. MYC-dependent T-acute lymphoblastic leukemia (T-ALL) cells reprogram metabolism by stabilizing DLST protein, and rely heavily on its elevated levels for proliferation and survival. Heterozygous loss of dlst in zebrafish does not impair development yet significantly delays the onset of MYC-induced T-ALL that resembles a major subtype of human disease with poor prognosis. DLST is a transferase in the tricarboxylic acid (TCA) cycle and mediates the conversion of α-ketoglutarate (α-KG) to succinyl-CoA. α-KG is a key cycle intermediate that simultaneously functions as an obligatory cofactor for α-KG-dependent dioxygenases (α-KGDO, e.g., demethylases), thus linking cellular metabolism with epigenetic controls of the cell. We hypothesize that: DLST protein stabilization accelerates α-KG conversion, enhances TCA cycle function, and suppresses α-KGDO activities, thus promoting leukemic cell proliferation and survival. In Aim 1 of this application we will apply genetic, pharmacological and biochemical approaches to determine the mechanisms by which DLST is stabilized in MYC-overexpressing T-ALL cells and identify novel DLST interactors including its E3 ligase(s). The zebrafish T-ALL model will then be utilized to define the role of key DLST regulators/interactors in T-ALL pathogenesis. In Aim 2, we will combine the analyses of the in vivo zebrafish model and human T-ALL cells to identify the biochemical and epigenetic changes associated with DLST inactivation, as well as functionally characterize key α-KGDO regulated by DLST in T-ALL pathogenesis. In Aim 3, we will investigate the targetability and compensatory pathways of DLST in relapsed/refractory T-ALL by using our newly identified DLST inhibitor and in vivo animal models including murine patient-derived xenografts. The innovation of this application lies in the study of DLST as a novel “oncorequisite” enzyme that regulates both metabolism and epigenetic status of the cell in a physiologically relevant in vivo zebrafish system. Indeed, this innovative system has enabled us to identify MYC and AMP-activated protein kinase as regulators for DLST and isocitrate dehydrogenase 2 as its compensatory gene. This research is significant in that it will deepen our understanding of leukemia pathogenesis and cancer metabolism, as well as the metabolo-epigenetic connections in MYC-dependent leukemic cells, with the long-term goal of developing novel therapeutic strategies against DLST-mediated pathways in cancer cells.