Investigating how cancer cells maintain redox homeostasis to support biomass production

研究癌细胞如何维持氧化还原稳态以支持生物质生产

• 批准号: 10381831
• 负责人: Sarah M Chang
• 金额: $ 5.18万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2026-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10381831
• 关键词: ATP Synthesis Pathway; Affect; Amino Acids; Biomass; Caloric Restriction; Cancer Patient; Cancer cell line; Cell Proliferation; Cells; Citrates; Clinical; Consumption; Coupled; Development; Environment; Enzymes; Equilibrium; Fatty Acids; Fermentation; Glucose; Glutamine; Goals; Homeostasis; Lactate Dehydrogenase; Lead; Lipids; Malignant Neoplasms; Measures; Mediator of activation protein; Metabolic; Metabolism; Mitochondria; NADH; Natural regeneration; Niacinamide; Non-Essential Amino Acid; Nucleotides; Nutrient; Oxidants; Oxidation-Reduction; Oxidative Phosphorylation; Oxides; Pathway interactions; Physiological; Process; Production; Proliferating; Protein Biosynthesis; Proteins; Protons; Pyruvate; Reaction; Research; Respiration; Role; Serine; Testing; Therapeutic; Tissues; cancer cell; cancer therapy; cancer type; cofactor; cost; dietary restriction; improved; insight; interest; mouse model; novel; oxidation; preservation; response; success; tumor; tumor growth; tumor metabolism; tumorigenesis; uptake

Project Summary To proliferate, cells must synthesize sufficient biomass, including nucleotides, proteins, and lipids. This is particularly important for rapidly proliferating cancer cells, which reprogram metabolism to meet the increased biosynthetic demands of proliferation. However, biosynthetic demands differ across cancer types and physiological environments. How cancer cells alter metabolism in response to specific biosynthetic demands is not well characterized, and better understanding these alterations will reveal metabolic liabilities that can be targeted to inhibit tumor growth. To synthesize biomass, cells require electron acceptors to oxidize nutrients like glucose and glutamine into biomass precursors, such as amino acids for protein synthesis and citrate for fatty acid synthesis. One essential electron acceptor is the redox cofactor NAD+. The ratio of oxidized NAD+ to reduced NADH (NAD+/NADH) influences the cellular redox state and reflects NAD+ availability for oxidative biosynthetic reactions. Thus, a sufficiently oxidized NAD+/NADH ratio must be maintained to enable synthesis of oxidized biomass and can limit cancer cell proliferation. We have found that increased demands for the amino acid serine and the lipid precursor citrate elevate the NAD+ demand, yet cancer cells surprisingly maintain a similar NAD+/NADH ratio, indicating that cells preserve NAD+/NADH homeostasis despite increased demands for oxidized biomass synthesis. The goal of the proposed research is to determine how cancer cells maintain NAD+/NADH homeostasis to support increased oxidative biosynthetic demands and tumor growth. I hypothesize that cancer cells maintain the NAD+/NADH ratio by modulating NAD+ regeneration, consumption, and synthesis to support biomass production. To test this hypothesis, I will use both cancer cell lines and mouse models to investigate how cancer cells and tumors maintain NAD+/NADH homeostasis in lipid-depleted conditions, a nutrient environment that increases cellular NAD+ demand for citrate production and is a physiological condition faced by cancer cells in the body. In Aim 1, I will investigate whether cancer cells increase three mechanisms of NAD+ regeneration to maintain redox homeostasis for lipid synthesis and tumor growth: fermentation, mitochondrial respiration, and uncoupling mitochondrial respiration from ATP synthesis. In Aim 2, I will investigate whether decreased flux through select NAD+ consuming redox reactions increases NAD+ availability for lipid synthesis. In Aim 3, I will investigate if NAD+ salvage synthesis from nicotinamide helps maintain a sufficiently oxidized NAD+/NADH ratio for increased lipid synthesis and tumor growth. The results of this study will lead to a better understanding of how cancer cells adapt to different nutrient and tissue environments and provide insight into a fundamental process in which cancer cells must engage to maintain redox homeostasis for proliferation. This will improve therapeutic approaches that target cancer metabolism and lead to the development of more effective and selective cancer treatments.

项目概要 为了增殖，细胞必须合成足够的生物量，包括核苷酸、蛋白质和脂质。这 对于快速增殖的癌细胞尤其重要，癌细胞会重新编程新陈代谢以满足增加的需求 增殖的生物合成需求。然而，不同癌症类型和生物合成的需求不同 生理环境。癌细胞如何改变新陈代谢以响应特定的生物合成需求 尚未得到很好的表征，更好地理解这些改变将揭示可 从而达到抑制肿瘤生长的目的。 为了合成生物质，细胞需要电子受体来氧化葡萄糖和谷氨酰胺等营养物质 转化为生物质前体，例如用于蛋白质合成的氨基酸和用于脂肪酸合成的柠檬酸盐。一 重要的电子受体是氧化​​还原辅因子NAD+。氧化型 NAD+ 与还原型 NADH 的比率 (NAD+/NADH) 影响细胞氧化还原状态并反映 NAD+ 对氧化生物合成的可用性 反应。因此，必须保持充分氧化的 NAD+/NADH 比例，以实现氧化的合成 生物量并可以限制癌细胞增殖。我们发现对氨基酸丝氨酸的需求增加 脂质前体柠檬酸盐提高了 NAD+ 的需求，但癌细胞却惊人地保持了类似的水平 NAD+/NADH 比率，表明尽管对 NAD+/NADH 的需求增加，细胞仍保持 NAD+/NADH 稳态 氧化生物质合成。拟议研究的目标是确定癌细胞如何维持 NAD+/NADH 稳态支持增加的氧化生物合成需求和肿瘤生长。我假设 癌细胞通过调节 NAD+ 再生、消耗和合成来维持 NAD+/NADH 比例 支持生物质生产。为了验证这个假设，我将使用癌细胞系和小鼠模型来 研究癌细胞和肿瘤如何在脂质耗尽的条件下维持 NAD+/NADH 稳态， 增加细胞对柠檬酸盐生产的 NAD+ 需求的营养环境，是一种生理条件 面对体内的癌细胞。在目标 1 中，我将研究癌细胞是否增加了三种机制： NAD+ 再生以维持脂质合成和肿瘤生长的氧化还原稳态：发酵、 线粒体呼吸，以及将线粒体呼吸与 ATP 合成解偶联。在目标 2 中，我将 研究通过选择 NAD+ 消耗氧化还原反应减少通量是否会增加 NAD+ 的可用性 用于脂质合成。在目标 3 中，我将研究烟酰胺中的 NAD+ 补救合成是否有助于维持 充分氧化的 NAD+/NADH 比例可增加脂质合成和肿瘤生长。本研究结果 将有助于更好地了解癌细胞如何适应不同的营养和组织环境， 深入了解癌细胞必须参与维持氧化还原稳态的基本过程 增殖。这将改善针对癌症代谢的治疗方法，并导致 开发更有效和选择性的癌症治疗方法。