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抗药性的出现，这使得确定新的目标和策略以干预一些人类恶性肿瘤至关重要。这项多PI指导的研究将开始确定先前未知的、可逆的蛋白质翻译后修饰(赖氨酸琥珀酸化和丙二酸化)在恶性状态发展中的重要性。本申请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质修饰。这些修饰似乎受线粒体蛋白SIRT5的调控，SIRT5是Sir2蛋白家族的成员(沉默信息调节因子2)。第二个问题涉及重新关注细胞代谢在癌症进展中所扮演的角色。尤其是癌细胞表现出的糖酵解活性增强(“Warburg效应”)和显著升高的谷氨酰胺代谢(即“谷氨酰胺成瘾”)。结合我们的初步发现，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新的假设，即癌症代谢中关键酶的脱琥珀酸化和/或去丙氨酸化对于满足恶性转化的生物合成和生物能量要求是必不可少的。我们将在细胞培养实验(目标1)和小鼠模型(目标2)中检验这一假设，并描绘癌细胞恶性状态要求去丙二醛/去琥珀酸化的分子机制(目标1)。此外，我们认为，靶向SIRT5并阻断其调节癌细胞中这些翻译后修饰的能力将为干预这种疾病提供新的方法。我们将识别针对SIRT5(目标3)的新型小分子抑制剂，并展示它们在细胞培养(目标1)和Kras诱导肺癌小鼠模型(目标2)中阻止恶性转化的有效性，这是一种特别需要开发新的治疗策略的恶性肿瘤。虽然部分肺癌可以用EGF受体抑制剂成功治疗，但大约25%-50%携带Kras基因突变的肺腺癌对这些抑制剂和化疗都具有耐药性，针对Kras的临床有效药物仍然难以找到。因此，我们认为，开发针对这些新颖的SIRT5调节的翻译后修饰的策略作为一种手段来帮助“重置”改变的癌细胞代谢，代表了一种变革性的方法，最终可能被证明对肺癌患者有利，并提供针对广泛的人类恶性肿瘤的一般治疗益处，因为癌症中代谢变化的基本性质。

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.