Identification of Metabolic Vulnerabilities of Ras-Driven Cancer Cells

描述（由申请人提供）：ras驱动癌细胞的代谢脆弱性鉴定肿瘤生长需要蛋白质、DNA、RNA和膜的生物合成。细胞代谢为这种生物合成提供了底物和能量。与代谢在癌症生长中的核心作用一致，代谢改变是癌症的一个标志。最著名的例子是即使在有氧气的情况下也能进行葡萄糖发酵，即“华宝效应”。最近，人们发现癌基因的一个主要功能是诱导代谢变化，包括Warburg效应，为促进肿瘤生长的生物合成提供底物和能量。因此，癌细胞易受代谢途径的干扰，因此需要针对代谢进行癌症治疗。Ras基因是癌症中最常发生突变的致癌基因之一，它们的突变激活诱导了Warburg效应。与许多致癌信号蛋白不同，目前还没有安全有效的激活Ras的药理学抑制剂，这增加了理解Ras驱动肿瘤代谢脆弱性的重要性。我们最近通过代谢组学和同位素示踪剂研究检查了肿瘤细胞中Ras激活的代谢后果。这表明Ras不仅可以诱导有氧糖酵解，还可以减少葡萄糖和脂肪酸的乙酰辅酶a的产生，并增强TCA循环对谷氨酰胺的依赖性，显示出代谢脆弱性。此外，我们发现Ras激活了自噬的分解代谢细胞自消化过程，自噬维持了TCA循环代谢，激活Ras的肿瘤细胞依赖自噬生存和肿瘤发生。因此，激活的Ras导致自噬成瘾，揭示了另一种代谢脆弱性。我们的统一假设是，Ras减少了葡萄糖和脂肪酸对TCA循环的输入，从而产生了对谷氨酰胺和其他自噬提供的TCA循环底物的需求，以维持肿瘤细胞的代谢。在这里，我们的目标是验证这一假设，并更全面地了解Ras诱导的代谢改变的潜在机制、普遍性以及利用它们的最佳方法。为此，我们将结合最先进的代谢组学与由Ras或下游激酶Akt和Raf驱动的体外和体内癌症模型。这项研究的最终效果将是极大地增加对致癌基因信号传导和代谢相互作用的理解，并以此确定ras驱动型癌症的新治疗靶点。该项目是Eileen White博士（罗格斯大学）和Josh Rabinowitz博士（普林斯顿大学）实验室之间非常富有成效的合作的直接延伸，此前由NIH癌症代谢挑战基金资助。

DESCRIPTION (provided by applicant): Identification of Metabolic Vulnerabilities of Ras-Driven Cancer Cells Tumor growth requires biosynthesis of protein, DNA, RNA, and membrane. Cellular metabolism provides the substrates and energy for this biosynthesis. Consistent with the central role of metabolism in cancer growth, altered metabolism is a hallmark of cancer. The best-known example is avid glucose fermentation even in the presence of oxygen, i.e., the "Warburg effect". Recently, it has become clear that a major function of oncogenes is to induce metabolic changes, including the Warburg effect, to provide substrates and energy for biosynthesis that enables tumor growth. Thus cancer cells are vulnerable to interference in metabolic pathways, hence the need to target metabolism for cancer therapy. Ras genes are among the most frequently mutated oncogenes in cancer, and their mutational activation induces the Warburg effect. Unlike for many oncogenic signaling proteins, there are no safe and effective pharmacological inhibitors of activated Ras, increasing the importance of understanding metabolic vulnerabilities of Ras-driven tumors. We have recently examined the metabolic consequences of Ras activation in tumor cells via metabolomics and isotope-tracer studies. This revealed that Ras not only induces aerobic glycolysis, but also decreases acetyl-CoA production from glucose and fatty acids, and enhances dependence of the TCA cycle on glutamine, revealing a metabolic vulnerability. Moreover, we found that Ras activates the catabolic cellular self-digestion process of autophagy, that autophagy sustains TCA cycle metabolism, and that tumor cells with activated Ras are dependent on autophagy for survival and tumorigenesis. Thus, activated Ras leads to autophagy addiction, revealing another metabolic vulnerability. Our unifying hypothesis is that Ras decreases input into the TCA cycle from glucose and fatty acids, creating the requirement for glutamine and other autophagy-supplied TCA cycle substrates to sustain tumor cell metabolism. Here we aim to test this hypothesis and understand more comprehensively the underlying mechanisms, generality of the metabolic alterations induced by Ras and the best ways to exploit them. To this end we will combine state-of-the-art metabolomics with in vitro and in vivo cancer models driven by Ras or the downstream kinases Akt and Raf. The net effect of this research will be to dramatically increase understanding of the interplay of oncogene signaling and metabolism, and in so doing to identify new therapeutic targets for Ras-driven cancers. This project is a direct extension of the very productive collaboration between the laboratories of Dr. Eileen White (Rutgers University) and Dr. Josh Rabinowitz (Princeton University) previously funded by a NIH Challenge Grant on cancer metabolism. PUBLIC HEALTH RELEVANCE: We have known for over 50 years that a major feature that distinguishes normal cells from cancer cells is altered metabolism. Only recently has it become clear that activation of oncogenes and loss of tumor suppressor genes reprograms metabolism to generate the building blocks for production of new tumor cells and to meet the energy requirements for cancer cell growth. Oncogenic forms of Ras dramatically alter cellular metabolism, promote tumorigenesis and are associated with poor prognosis. Targeting Ras therapeutically has been difficult, necessitating approaches to block pathways, such as metabolic pathways, downstream of Ras. We propose to use state-of-the-art mass spectrometry and cancer models to determine how Ras alters metabolism. This will expose vulnerabilities that can be exploited in the development of new cancer therapies.