Understanding metabolic pathways that support redox homeostasis in cancer

项目总结/摘要 胰腺导管腺癌（PDAC）癌细胞在特别是纤维化和变性的胰腺内增殖。 血管化不良的肿瘤尽管PDAC细胞存在于肿瘤环境中，但其具有有限的 营养素和氧气，这些细胞仍然积极增殖和生长。有限 在这种环境中，由氧限制引起的电子传递链（ETC）活动产生了一种 氧化还原平衡问题，使得NADH不能通过ETC再循环为NAD+。根据这些 条件下，NAD+可以成为生长的限制，我们称之为电子受体的条件 不足在缺氧条件下增殖的细胞必须克服这种电子受体 不足，以扩散。我们假设氧气限制导致依赖于 替代代谢途径，以维持氧化还原平衡、生物质合成和增殖。 虽然许多研究都集中在遗传因素引发的异常PDAC代谢， 这种恶性肿瘤常见的改变，对环境的了解很少- 肿瘤细胞代谢的依赖性改变是PDAC增殖所必需的， 氧气和养分限制条件。拟议的工作将确定代谢 缺氧引起的PDAC细胞的需求。首先我会测试一下 无法解释的PDAC代谢表型可能会驱动反应，使这些细胞 在有限的氧气中增殖。具体来说，我将测试脯氨酸和脂肪酸 代谢允许低氧PDAC细胞克服电子受体不足， 对于缺氧PDAC增殖功能重要。最后，我将执行一个代谢基因 靶向CRISPR/Cas9筛选，以确定代谢所需的一组代谢酶， 环境缺氧下PDAC氧化还原稳态和增殖。的结果予以 这项研究将首次确定PDAC细胞维持氧化还原平衡所需的代谢途径 在缺氧状态下。这将为理解PDAC细胞如何继续 在严重限制扰乱细胞氧化还原平衡的条件下增殖， 合成生长所需的代谢物。这是重要的，因为靶向抑制一组 PDAC电池用于维持氧化还原平衡并阻止电子受体的反应 缺素可选择性抑制PDAC细胞增殖，具有治疗价值。因此，在本发明中， 这项工作可以揭示根据这些环境背景来确定PDAC目标的方法， 癌的

Project Summary/Abstract Pancreatic ductal adenocarcinoma (PDAC) cancer cells proliferate within particularly fibrotic and poorly vascularized tumors. Although PDAC cells exist within a tumor environment with limited nutrients and oxygen, these cells nevertheless aggressively proliferate and grow. Limited electron transport chain (ETC) activity caused by oxygen limitation in this environment creates a redox balance problem such that NADH cannot be recycled by the ETC to NAD+. Under these conditions, NAD+ can become limiting for growth, a condition we term electron acceptor insufficiency. Cells proliferating under hypoxic conditions must overcome this electron acceptor insufficiency in order to proliferate. We hypothesize that oxygen limitation leads to reliance on alternative metabolic pathways to maintain redox balance, biomass synthesis and proliferation. While many studies have focused on aberrant PDAC metabolism triggered by genetic alterations common to this malignancy, there is little understanding of the environment- dependent alterations in tumor cell metabolism that are required for PDAC proliferation in harsh oxygen and nutrient limiting conditions. The proposed work will identify the metabolic requirements of PDAC cells brought on by hypoxia. First I will test whether otherwise unexplained PDAC metabolic phenotypes might drive reactions that allow these cells to proliferate in limited oxygen. Specifically, I will test the hypotheses that proline and fatty acid metabolism allow hypoxic PDAC cells to overcome electron acceptor insufficiency and are functionally important for hypoxic PDAC proliferation. Lastly, I will perform a metabolic gene targeted CRISPR/Cas9 screen, to identify the set of metabolic enzymes that are required for PDAC redox homeostasis and proliferation under environmental hypoxia. The results of these studies will be the first to identify metabolic pathways that PDAC cells require for redox balance under hypoxia. This will provide a metabolic basis for understanding how PDAC cells continue to proliferate under conditions that otherwise severely limit perturb cellular redox balance and synthesis of metabolites required for growth. This is important as targeted inhibition of the set of reactions that PDAC cells use to maintain redox balance and prevent electron acceptor insufficiency may selectively prevent PDAC cell proliferation and have therapeutic value. Thus, this work may reveal ways to target PDAC based on the environmental context of these cancers.