Metabolic vulnerabilities in cancers with impaired TCA cycle activity

项目总结 癌细胞利用多种代谢策略来产生生物合成前体，从而助长恶性 扩散。这种代谢冗余和可塑性阻碍了针对癌症的治疗的有效性 并强调了确定最有可能对代谢反应的肿瘤类型的重要性 抑制剂。这项提议的目标是检验代谢途径受损的肿瘤将 在产生关键的生物合成中间体方面代谢可塑性有限，使它们容易患上 代谢抑制。我们关注的是三羧酸(TCA)循环，它是一个中心代谢中枢， 支持细胞生长，但在几种形式的人类肾细胞癌(RCC)中被截断或受损。一个 肾细胞癌的亚群起源于核心TCA循环酶琥珀酸脱氢酶种系缺陷 (SDH)或富马酸水合酶(FH)；更常见的是，肾细胞癌有过度活跃的低氧诱导因子。 (HIF)信号，钝化TCA循环新陈代谢。这项提案的目标是确定这些 TCA循环活性改变的肾癌肿瘤依赖于ATP柠檬酸裂解酶(ACL)作为一种 关键代谢中间体的替代来源。天冬氨酸，由三氯乙烷环中间体合成 草酰乙酸酯，支持核苷酸和蛋白质合成，已成为肿瘤的关键限制因素 成长。然而，TCA循环通量受损的肿瘤如何维持天冬氨酸的生成--以及 这些补偿途径代表了一种有针对性的负债--在很大程度上仍不为人所知。我的初步数据 证明SDH/FH缺陷或HIF活性的RCC细胞相对于它们的 同基因对照和ACL抑制选择性地损害这些具有TCA周期缺陷细胞的存活 新陈代谢。在目标1中，我将利用一组等基因RCC株系来测试遗传和药理学 在体外和体内，ACL抑制特异性地损害SDH/FH缺陷的肾癌细胞的生长。我会利用 提供细胞内天冬氨酸的遗传工具，以测试天冬氨酸供应是 SDH/FH缺陷细胞的ACL要求。在目标2中，我将使用具有由Lost驱动的高活性HIF的RCC细胞 用von Hippel Lindau肿瘤抑制因子确定氧化TCA循环受抑的细胞 活性依赖于ACL产生天冬氨酸，并使其能够在体外和体内生长。这些研究将使 光不仅在SDH-/FH-/VHL阴性肿瘤中潜在的代谢阿喀琉斯跟部，而且还将作为证据 具有TCA循环功能障碍的癌细胞将ACL作为替代合成途径的原理 合成代谢前体。本提案中概述的工作和培训计划将在以下实验室完成 莉迪亚·芬利博士和罗斯·莱文博士在纪念斯隆·凯特琳癌症中心的共同建议和威尔 理想的做法是让申请者为进一步的临床培训做好准备，并成为一名独立的内科科学家。

PROJECT SUMMARY Cancer cells exploit multiple metabolic strategies to generate biosynthetic precursors that fuel malignant proliferation. Such metabolic redundancy and plasticity hampers effectiveness of therapies that target cancer cell metabolism and underscores the importance of identifying tumor types most likely to respond to metabolic inhibitors. The goal of this proposal is to test the hypothesis that tumors with impaired metabolic pathways will have limited metabolic plasticity in generating critical biosynthetic intermediates, rendering them susceptible to metabolic inhibition. We focus on the tricarboxylic acid (TCA) cycle, which is a central metabolic hub that supports cell growth and yet is truncated or impaired in several forms of human renal cell cancer (RCC). A subset of RCC tumors arise from germline deficiencies in core TCA cycle enzymes succinate dehydrogenase (SDH) or fumarate hydratase (FH); more commonly, RCC tumors have hyperactive hypoxia-inducible factor (HIF) signaling that blunts TCA cycle metabolism. The goal of this proposal is to determine whether these RCC tumors with altered TCA cycle activity are dependent upon ATP citrate lyase (ACL) as an alternative source of critical metabolic intermediates. Aspartate, synthesized from TCA cycle intermediate oxaloacetate, supports nucleotide and protein synthesis and has emerged as a critical limitation for tumor growth. Nevertheless, how tumors with impaired TCA cycle flux sustain aspartate generation—and whether these compensatory pathways represent a targetable liability—remains largely unknown. My preliminary data demonstrate that SDH/FH-deficient or HIF-active RCC cells have reduced aspartate pools relative to their isogenic controls and that ACL inhibition selectively impairs survival of these cells with defective TCA cycle metabolism. In Aim 1, I will leverage a panel of isogenic RCC lines to test whether genetic and pharmacologic ACL inhibition specifically impairs growth of SDH-/FH-deficient RCC cells in vitro and in vivo. I will exploit genetic tools that supply intracellular aspartate to test the hypothesis that aspartate provision underlies the ACL requirement in SDH-/FH-deficient cells. In Aim 2, I will use RCC cells with hyperactive HIF driven by loss of the von Hippel Lindau tumor suppressor to determine whether cells with suppressed oxidative TCA cycle activity depend on ACL to produce aspartate and enable growth in vitro and in vivo. These studies will shed light not only on a potential metabolic Achilles heel in SDH-/FH-/VHL-null tumors but will also serve as proof of principle that cancer cells with TCA cycle dysfunction engage ACL as an alternative route of synthesizing anabolic precursors. The work and training plan outlined in this proposal will be completed in the laboratory of Dr. Lydia Finley with the co-advisement of Dr. Ross Levine at Memorial Sloan Kettering Cancer Center and will ideally prepare the applicant for further clinical training and a career as an independent physician-scientist.