Defining and Targeting Malic Enzyme Dependence in Pancreatic Cancer

项目总结/摘要 胰腺癌是最致命的主要癌症，5年生存率 低于10%。这主要是由于缺乏有效的治疗方案。生理和 胰腺肿瘤的生物化学性质是这种治疗抗性的基础。PDA细胞 存在于致密、纤维化并因此营养耗尽的肿瘤微环境中。可以预见， 在PDA细胞中，新陈代谢被重新编程以促进其维持和生长。比如说， 我们的研究小组最近描述了一种PDA细胞利用的非经典途径， #21453;力，从而充分发挥其发展潜力。最近，我的初步结果 发现抑制苹果酸酶1（ME 1），这一代谢途径中的最后一种酶， 在体外和体内显著抑制肿瘤生长。在哺乳动物中有三种ME同工型， ME1-3我发现ME 1依赖性和ME 2表达之间存在负相关， PDA手机。换句话说，ME 1依赖性PDA细胞具有低/无ME 2，并且ME 2表达 PDA细胞对ME 1抑制具有抗性。有趣的是，近50%的PDA表达低/无ME 2。 ME 2在染色体上与SMAD 4非常接近，SMAD 4是PDA中丢失的肿瘤抑制因子。基于 在它们的基因组位置上，ME 2的共丢失也经常发生。因此，ME 2的损失 提供了ME 1依赖性合成致死率和患者分层的潜在背景 ME 1抑制剂的方法。因此，有一个基本的需要，以了解功能 ME的作用，以便利用PDA中这种独特的治疗弱点。 该项目的工作假设是，细胞质之间存在功能冗余， ME 1和线粒体ME 2。当ME 1受损时，ME 2提供代谢/氧化还原 代偿活动此外，ME 2表达的缺失提供了ME 1依赖性的环境。 合成杀伤力这将分两部分进行测试。(Aim 1）从机制上讲，代谢和 将定义ME在PDA生长中的亚细胞功能。ME的代谢作用将是 改变后通过稳态代谢组学、同位素示踪和流式细胞术检查 我的表达。ME的亚细胞定位和潜在的物理相互作用将 也被调查。(Aim 2）在功能上，ME 1和ME 2之间的补偿作用对 PDA生长将在体外、离体和体内使用基因敲除/敲除进行检查， 过度表达这些研究将有助于我们理解 调节PDA的代谢和ME的作用。此外，他们将铺平道路， 针对PDA的ME 1靶向药物的开发，同时也为患者提供了一种策略， 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.