DNA Repair of Endogenous Lesions in Carcinogenesis

癌变过程中内源性病变的 DNA 修复

• 批准号: 7267034
• 负责人: RABINDRA ROY
• 金额: $ 29.05万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-26 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7267034
• 关键词: 2-butenal; 4 hydroxynonenal; 8-hydroxyguanosine; 8-oxoguanine; Abbreviations; Acrolein; Address; Adenine; Age; Aldehydes; Animal Model; Animals; Base Excision Repairs; Biological Assay; Chronic; Chronic Hepatitis; Cinnamon - dietary; Copper; DNA; DNA Adducts; DNA Damage; DNA Repair; DNA glycosylase; Data; Development; Disease; Environmental Exposure; Enzymes; Excision; Genes; Goals; Hepatitis; Hepatocarcinogenesis; Hepatocyte; Hepatolenticular Degeneration; Human; Hydrogen Peroxide; Hydroxyl Radical; Inbred LEC Rats; Induced Mutation; Inflammation; Iron; Leg; Lesion; Life; Link; Lipids; Liver; Liver Extract; Localized; Long-Evans Rats; Luciferases; Lung; Malignant Neoplasms; Malignant neoplasm of liver; Malondialdehyde; Mammalian Cell; Mediating; Messenger RNA; Metabolism; Metals; Methylpurine DNA Glycosylase; Modeling; Molecular; Molecular Profiling; Mus; Mutation; Nucleotide Excision Repair; OGG1 gene; Organ; Oxidative Stress; Pathway interactions; Patients; Play; Primary carcinoma of the liver cells; Rat Strains; Rate; Rattus; Reactive Oxygen Species; Regulation; Reporter; Reporting; Research Personnel; Risk; Role; Staging; TP53 gene; Testing; Thinking; Time; Tissue Extracts; Tissues; Tuberous Sclerosis; Tumor Promotion; Tumor Suppressor Genes; Uracil; Variant; adduct; age group; base; cancer prevention; cancer risk; carcinogenesis; dihydrouracil; endonuclease III; experience; genotoxicity; human APEX1 protein; mutant; nervous system disorder; oxidative DNA damage; perhydroxyl radical; plasmid DNA; programs; promoter; repair enzyme; repaired; thymine glycol; tumor; tumorigenesis; uracil-DNA glycosylase

DESCRIPTION (provided by applicant): The broad long-term goal of this project is to elucidate the role of repair of endogenously modified DNA in the prevention of cancer. Our overall hypothesis is that the repair of endogenous DNA damage, including oxidized bases (Reactive Oxygen Species (ROS)-induced) and cyclic DNA adducts (enal-induced), plays a critical role in carcinogenesis. ROS and enals as such have been shown to elicit tumor promotion but detailed molecular mechanisms need to be elucidated. In this project we will use the Long Evans Cinnamon (LEG) rat as a model to investigate the mechanism. The LEG rat is genetically predisposed to spontaneous hepatocellular carcinoma (HCC). Like Wilson's disease (WD) patients, LEG rats accumulate excess copper in the liver and consequently the organ experiences severe inflammation and oxidative stress. As a result, the LEG rats develop hepatitis and the surviving animals get liver cancer. An important question is whether the chronic oxidative stress impairs repair capacity in LEG rats and as a consequence the increased oxidative damage and exocyclic adduct burden plays a critical role in HCC in LEG rat livers. Our preliminary results showed that DNA glycosylases (such as OGG1 and NTH1)-mediated excision activity of oxidized bases (8-oxoguanine and dihydrouracil) was significantly altered at different stages of HGG development in LEG rat compared to that in the control Long Evans Agouti (LEA) rat livers, and, thus prompted us to propose the following specific aims. These are to: (1) study activity and expression of repair DNA glycosylases and/or other enzymes, if found to be rate-limiting, in base excision repair (BER) pathway for repairing oxidized bases and etheno adducts in LEG and LEA rat livers, with lungs as a control; (2) study the mechanisms of regulation of NTH1 expression in LEG rat liver; (3) examine the mechanism of variation of expression and/or activity, if any, of DNA glycosylase(s) and/or other rate-limiting BER enzymes by assessing the effects of metals (copper and iron), hydrogen peroxide, and enals in hepatocytes of LEA and LEG rats and comparing the effects with that observed in tissues obtained from Aim 1; (4) study capacity to repair cyclic propano adducts (Acr-, Cro-, and HNE-dG) in LEG and LEA rat livers and lungs as control. Our preliminary results showed that HNE-dG, a major cyclic propano adduct is repaired by nucleotide excision repair (NER) pathway in mammalian cells including LEA and LEG livers. So, we will also examine the mechanism of variation, if found, of expression and/or activity of rate-limiting NER enzymes for repairing propano adducts by assessing the effects of enals in hepatocytes of LEA and LEG rats and comparing the effects with that observed in tissues. In summary, the data obtained by this project will be useful in elucidating the role of the endogenous DNA damage (oxidized bases and cyclic DNA adducts), and their repair in mutation and liver carcinogenesis.

描述（由申请人提供）：该项目的长期目标是阐明内源性修饰 DNA 的修复在预防癌症中的作用。我们的总体假设是，内源性 DNA 损伤的修复，包括氧化碱基（活性氧 (ROS) 诱导的）和环状 DNA 加合物（烯醛诱导的），在致癌过程中发挥着关键作用。 ROS 和烯醛本身已被证明可引起肿瘤促进，但需要阐明详细的分子机制。在本项目中，我们将使用 Long Evans Cinnamon (LEG) 大鼠作为模型来研究其机制。 LEG 大鼠在遗传上易患自发性肝细胞癌 (HCC)。与威尔逊病 (WD) 患者一样，LEG 大鼠的肝脏中积累了过量的铜，因此该器官会经历严重的炎症和氧化应激。结果，LEG 大鼠患上肝炎，而幸存的动物患上肝癌。一个重要的问题是，慢性氧化应激是否会损害 LEG 大鼠的修复能力，因此氧化损伤和环外加合物负荷的增加在 LEG 大鼠肝脏的 HCC 中发挥着关键作用。我们的初步结果表明，与对照 Long Evans Agouti 相比，在 LEG 大鼠 HGG 发育的不同阶段，DNA 糖基酶（如 OGG1 和 NTH1）介导的氧化碱基（8-氧代鸟嘌呤和二氢尿嘧啶）切除活性显着改变。 LEA）大鼠肝脏，因此促使我们提出以下具体目标。这些目的是：(1) 研究碱基切除修复 (BER) 途径中修复 DNA 糖基化酶和/或其他酶的限速活性和表达，用于修复 LEG 和 LEA 大鼠肝脏中的氧化碱基和乙烯加合物，以肺作为对照； (2)研究LEG大鼠肝脏NTH1表达的调控机制； (3) 通过评估金属（铜和铁）、过氧化氢和烯醛的影响，检查 DNA 糖基化酶和/或其他限速 BER 酶的表达和/或活性（如果有）的变化机制在 LEA 和 LEG 大鼠的肝细胞中，并将效果与在从目标 1 获得的组织中观察到的效果进行比较； (4) 研究 LEG 和 LEA 大鼠肝脏和肺中环状丙烷加合物（Acr-、Cro- 和 HNE-dG）的修复能力（作为对照）。我们的初步结果表明，HNE-dG（一种主要的环丙烷加合物）在包括 LEA 和 LEG 肝脏在内的哺乳动物细胞中通过核苷酸切除修复（NER）途径进行修复。因此，如果发现的话，我们还将通过评估 LEA 和 LEG 大鼠肝细胞中 enal 的作用，并将效果与观察到的效果进行比较，来检查用于修复丙醇加合物的限速 NER 酶的表达和/或活性的变异机制。在组织中。总之，该项目获得的数据将有助于阐明内源性DNA损伤（氧化碱基和环状DNA加合物）及其修复在突变和肝癌发生中的作用。