Defining and Targeting Malic Enzyme Dependence in Pancreatic Cancer

项目摘要/摘要 摘要胰腺癌(Pda)是最具致命性的主要癌症，其五年存活率高。 低于10%。这很大程度上是由于缺乏有效的治疗选择。生理学和 胰腺肿瘤的生化特性是这种治疗抵抗的基础。PDA细胞 存在于致密、纤维化并因此缺乏营养的肿瘤微环境中。不出所料， PDA细胞的新陈代谢被重新编程，以促进它们的维持和生长。例如, 我们的研究小组最近描述了一种由PDA细胞用来介导氧化的非典型途径 压力，从而使它们能够充分发挥增长潜力。最近，我的初步结果 研究表明，抑制苹果酸酶1(ME1)是这一代谢途径中的最后一种酶，可以 显著抑制肿瘤的体外和体内生长。在哺乳动物中有三种ME亚型， ME1-3。我发现ME1依赖和ME2表达之间存在负相关 PDA细胞。换句话说，依赖ME1的PDA细胞有低/无ME2，并且ME2表达 PDA细胞对ME1抑制有抵抗作用。有趣的是，近50%的PDA表达低/无ME2。 Me2在染色体上与Smad4很接近，Smad4是一种在PDA中丢失的肿瘤抑制因子。基于 它们的基因组位置，ME2的共同缺失也经常发生。因此，ME2的损失 为ME1依赖的合成致命性和患者分层提供了潜在的背景 ME1抑制剂的检测方法。因此，有必要从根本上理解功能 MES的作用，以开发这一独特的治疗PDA的脆弱性。 该项目的工作假设是胞质之间存在功能冗余 ME1和线粒体ME2。当ME1受损时，ME2提供代谢/氧化还原 补偿活动。此外，ME2表达的丧失为ME1依赖提供了上下文 合成杀伤力。这将分两部分进行测试。(目标1)机械上，新陈代谢和 将明确MES在PDA生长中的亚细胞功能。MES的代谢作用将是 改变后进行稳态代谢组学、同位素示踪和流式细胞术检查 我的表情。MES的亚细胞定位和潜在的物理相互作用将 也被调查。(目标2)在功能上，ME1和ME2之间的补偿作用 将使用基因敲除和基因敲除技术检测PDA在体外、体外和体内的生长 过度表达。这些研究将有助于我们理解 调节PDA的代谢和MES的作用。此外，它们还将为 开发针对ME1的治疗PDA的药物，同时也为患者提供策略 分层。

Project Summary/Abstract Pancreatic adenocarcinoma (PDA) is the most lethal major cancer, with a 5-year survival rate below 10%. This is largely due to the lack of effective treatment options. The physiology and biochemical nature of pancreatic tumors is fundamental to this therapeutic resistance. PDA cells exist in a dense, fibrotic and thus, nutrient-depleted tumor microenvironment. Predictably, metabolism is reprogrammed in PDA cells to fuel their maintenance and growth. For example, our group recently described a non-canonical pathway utilized by PDA cells to mediate oxidative stress, thereby permitting their full growth potential. More recently, my preliminary results revealed that inhibition of malic enzyme 1 (ME1), the last enzyme in this metabolic pathway, can significantly blunt tumor growth in vitro and in vivo. There are three ME isoforms in mammals, ME1-3. I identified an inverse correlation between ME1 dependence and ME2 expression in PDA cells. In other words, ME1 dependent PDA cells have low/no ME2, and ME2 expressing PDA cells are resistant to ME1 inhibition. Intriguingly, nearly 50% of PDA express low/no ME2. ME2 is in close chromosomal proximity to SMAD4, a tumor suppressor lost in PDA. Based on their genomic location, co-loss of ME2 also frequently occurs. Therefore, the loss of ME2 provides a potential context for ME1-dependent synthetic lethality and a patient stratification method for ME1 inhibitors. There is therefore a fundamental need to understand the functional roles of MEs in order to exploit this unique therapeutic vulnerability in PDA. The working hypothesis of this project is that functional redundancy exists between cytosolic ME1 and mitochondrial ME2. When ME1 is impaired, ME2 provides metabolic/redox compensatory activity. Further, loss of ME2 expression provides a context for ME1-dependent synthetic lethality. This will be tested in two parts. (Aim 1) Mechanistically, the metabolic and subcellular functions of MEs in PDA growth will be defined. The metabolic roles of MEs will be examined by steady-state metabolomics, isotope tracing and flow cytometry following alteration of ME expression. The subcellular localization and potential physical interactions of MEs will also be investigated. (Aim 2) Functionally, the compensatory effect between ME1 and ME2 on PDA growth will be examined in vitro, ex vivo and in vivo using genetic knockdown/out and overexpression. These studies will contribute to our understanding of the mechanisms that regulate metabolism in PDA and the roles of MEs. Further they will pave the way for the development of ME1-targeted drugs for PDA, while also providing a strategy for patient stratification.