Linking cancer cell metabolic reprogramming to the DNA repair mechanism

 描述（由申请人提供）：代谢在癌细胞中广泛重新连接，以支持生物合成、生长和增殖。最近已经变得明显的是，许多组蛋白和DNA修饰对细胞代谢状态敏感。组蛋白乙酰化是一种动态的染色质修饰，组蛋白乙酰化的总体水平对代谢物乙酰辅酶A的可用性有响应。然而，组蛋白乙酰化的代谢控制的功能意义仍然知之甚少。Wellen实验室最近表明，癌细胞中PI 3 K-Akt通路的致癌激活促进乙酰辅酶A的产生和组蛋白乙酰化水平的升高，表明癌细胞中组蛋白乙酰化的正常代谢控制被破坏。广泛的染色质修饰，包括组蛋白乙酰化，在DNA修复的调控中起着至关重要的作用。Greenberg实验室最近表明，组蛋白H4赖氨酸16（H4 K16 ac）在DNA双链断裂（DSB）位点的乙酰化在招募DNA修复蛋白（如BRCA 1）和利用DNA修复机制中起着关键作用。DSB通过同源重组（HR）或非同源末端连接（NHEJ）修复。HR缺陷，如BRCA 1/2突变，导致基因组不稳定，是癌症易感性和对新兴化疗反应的主要原因。由于组蛋白乙酰化对乙酰辅酶A的可用性有反应，并且乙酰辅酶A代谢在癌细胞中经常失调，我们推测乙酰辅酶A可能影响DSB位点的H4 K16 ac水平以调节DNA修复效率。我们的初步数据表明，通过沉默代谢酶ATP-柠檬酸裂解酶（ACLY）来操纵核质乙酰辅酶A水平确实会影响修复蛋白到DSB位点的募集，在ACLY沉默后，pro-NHEJ因子53 BP 1的募集优于pro-HR BRCA 1。在该R21应用中，我们提出测试癌基因驱动的葡萄糖摄取和乙酰辅酶A产生影响DSB处的乙酰化状态并调节对DNA损伤剂的反应的假设。我们将通过首先测试乙酰辅酶A的可用性是否确实是DNA修复机制的关键决定因素，通过影响DSB中HR和NHEJ因子的平衡来实现这一假设。然后，我们将研究由PI 3 K-Akt和LKB 1-AMPK-ACC 1途径介导的乙酰辅酶A代谢改变对DNA修复机制的影响。这项研究有可能确定以前未被认识到的细胞代谢和DNA损伤反应之间的联系，并确定新的方法，使细胞对化疗药物敏感。

 DESCRIPTION (provided by applicant): Metabolism is extensively rewired in cancer cells to support biosynthesis, growth, and proliferation. It has recently become apparent that many histone and DNA modifications are sensitive to cellular metabolic state. Histone acetylation is a dynamic chromatin modification, and global levels of histone acetylation are responsive to availability of the metabolite acetyl-CoA. However, the functional significance of metabolic control of histone acetylation remains poorly understood. The Wellen lab has recently shown that oncogenic activation of the PI3K-Akt pathway in cancer cells promotes acetyl-CoA production and elevated histone acetylation levels, indicating that normal metabolic controls on histone acetylation are disrupted in cancer cells. Extensive chromatin modifications, including histone acetylation, play crucial roles in the regulation of DNA repair. The Greenberg lab has recently shown that acetylation of histone H4 lysine 16 (H4K16ac) at sites of DNA double strand breaks (DSBs) plays a key role in recruitment of DNA repair proteins such as BRCA1 and utilization of DNA repair mechanisms. DSBs are repaired either by homologous recombination (HR) or non-homologous end joining (NHEJ). HR deficiencies, such as occur with BRCA1/2 mutations, result in genome instability and are a major cause of cancer predisposition and response to emerging chemotherapies. Since histone acetylation is responsive to acetyl-CoA availability and acetyl-CoA metabolism is frequently deregulated in cancer cells, we postulated that acetyl-CoA might impact H4K16ac levels at DSB sites to modulate the DNA repair efficiency. Our preliminary data shows that manipulation of nuclear-cytoplasmic acetyl-CoA levels by silencing the metabolic enzyme ATP-citrate lyase (ACLY) indeed impacts the recruitment of repair proteins to DSB sites, with recruitment of pro-NHEJ factor 53BP1 favored over pro-HR BRCA1 upon ACLY silencing. In this R21 application, we propose to test the hypothesis that oncogene-driven glucose uptake and acetyl- CoA production impact the acetylation state at DSBs and modulate the response to DNA damaging agents. We will pursue this hypothesis by first testing whether acetyl-CoA availability is indeed a critical determinant o DNA repair mechanism by affecting the balance of HR and NHEJ factors at DSBs. We will then examine the influence of altered acetyl-CoA metabolism mediated by the PI3K-Akt and LKB1-AMPK-ACC1 pathways on the DNA repair mechanism. This study has potential to identify previously unrecognized links between cellular metabolism and the DNA damage response and to identify new approaches to sensitize cells to chemotherapeutics.