Succinylation and Malonylation as Novel Protein Modifications in Cancer

描述（由申请人提供）：许多癌症缺乏有效的治疗方法，以及对现有治疗方法的耐药性的出现，使得确定新的靶点和策略来干预许多人类恶性肿瘤变得至关重要。这项多pi导向的研究将着手建立以前未被认识到的，可逆的蛋白质翻译后修饰（赖氨酸琥珀酰化和丙二醛酰化）在恶性状态发展中的重要性。本应用程序中描述的研究源于两个令人兴奋的新研究进展。第一个是基于我们最近的发现，表明在细胞中的几种代谢酶上存在新的翻译后蛋白修饰。这些修饰似乎是由线粒体蛋白Sirt5调控的，Sirt5是Sir2蛋白家族的一员（Silent information regulator 2）。第二是重新关注细胞代谢在癌症进展中所起的作用。尤其是糖酵解活性增强（“Warburg效应”）和谷氨酰胺代谢显著升高(即。“谷氨酰胺成瘾”)。结合我们的初步研究结果表明Sirt5是许多人类癌细胞转化表型所必需的，这些不同的证据使我们提出了一个新的假设，即癌症代谢中关键酶的去琥珀酰化和/或去酰化对于满足恶性转化的生物合成和生物能量需求是必不可少的。我们将在细胞培养实验（目标1）和小鼠模型（目标2）中验证这一假设，并描述癌细胞恶性状态所需的脱丙烯酰化/去琥珀酰化的分子机制（目标1）。此外，我们相信靶向Sirt5并阻断其在癌细胞中调节这些翻译后修饰的能力将为干预这种疾病提供新的方法。我们将寻找特异性靶向Sirt5 （Aim 3）的新型小分子抑制剂，并在细胞培养（Aim 1）和kras诱导的肺癌小鼠模型（Aim 2）中证明它们在阻断恶性转化方面的有效性，这是一种特别需要开发新的治疗策略的恶性肿瘤。虽然一部分肺癌可以用EGF受体抑制剂成功治疗，但大约25-50%的含有Kras突变的肺腺癌对这些抑制剂和化疗都有耐药性，而且临床有效的靶向Kras的药物仍然难以捉摸。因此，我们认为，开发针对这些新的sirt5调节的翻译后修饰的策略，作为帮助“重新设置”癌细胞改变的代谢的手段，代表了一种变革性的方法，最终可能证明对肺癌患者有益，并提供针对广泛的人类恶性肿瘤的一般治疗益处，考虑到癌症代谢改变的基本性质。

DESCRIPTION (provided by applicant): The lack of effective treatments for many cancers and the occurence of resistance to available therapies make it critically important to identify new targets and strategies for intervention against a number of human malignancies. This multi-PI-directed study will set out to establish the importance of previously unrecognized, reversible protein posttranslational modifications (lysine succinylation and malonylation) in the development of the malignant state. The studies described in this application arise from two exciting new research developments. The first is based on our very recent discovery suggesting the existence of novel post-translational protein modifications on several metabolic enzymes in cells. These modifications appear to be regulated by the mitochondrial protein Sirt5, a member of the Sir2 family of proteins (for Silent information regulator 2). The second involves the renewed attention being directed toward understanding the roles played by cellular metabolism in cancer progression. This is especially the case for the enhanced glycolytic activity (the "Warburg effect") and markedly elevated glutamine metabolism (i.e. "glutamine addiction") exhibited by cancer cells. When combined with our preliminary findings suggesting that Sirt5 is required for the transformed phenotypes of a number of human cancer cells, these different pieces of evidence have led us to put forward the novel hypothesis that the desuccinylation and/or demalonylation of key enzymes in cancer metabolism are essential for satisfying the biosynthetic and bioenergetic requirements of malignant transformation. We will test this hypothesis in cell culture experiments (Aim 1) and mouse models (Aim 2), as well as delineate the molecular mechanisms underlying the requirement of demalonylation/desuccinylation for the malignant state of cancer cells (Aim 1). Moreover, we believe that targeting Sirt5 and blocking its ability to regulate these post-translational modifications in cancer cells will offer new approaches for intervention against this disease. We will identify novel small molecule inhibitors that specifically target Sirt5 (Aim 3) and demonstrate their effectiveness at blocking malignant transformation in cell culture (Aim 1) and in a mouse model of Kras-induced lung cancer (Aim 2), a malignancy for which the development of new therapeutic strategies is especially needed. While a subset of lung cancers can be treated successfully with EGF receptor inhibitors, the approximately 25-50% of lung adenocarcinomas harboring Kras mutations are resistant to these inhibitors as well as chemotherapy, and clinically effective drugs targeting Kras have remained elusive. Thus, we feel that developing strategies that target these novel Sirt5-regulated post- translational modifications as a means to help 're-set' the altered metabolism of cancer cells represents a transformative approach that could ultimately prove beneficial to lung cancer patients, as well as provide a general therapeutic benefit against a broad range of human malignancies, given the fundamental nature of metabolic alterations in cancer.