Molecular Mechanisms of Nitroarene Toxicity

描述(申请人提供)：癌症是一个通用的术语，指的是一百多种不同的疾病，其特征是细胞分裂不受控制，以及这些细胞侵袭和破坏周围正常组织的能力。从病因上讲，癌症是一种缓慢发展的疾病，受到多种因素的影响，包括暴露于环境毒素、生活方式、病毒感染和个人基因构成。已知的增加癌症风险的因素包括烟草烟雾、暴露在紫外线或电离辐射下，以及摄入空气、水或食物中存在的环境毒物。硝基芳烃是一种广泛存在于香烟烟雾、飞灰和柴油废气中的污染物。这些化合物与细胞DNA反应，形成巨大的碱基损伤，可能导致基因突变，最终触发致癌过程。核苷酸切除修复(NER)系统通过移除巨大的DNA损伤和恢复基因组完整性来对抗这些影响。着色性干皮病和Cockayne综合征是由NER缺乏引起的两种遗传病，它们是DNA损伤持续存在对人类健康造成破坏性后果的公然例子。在这项应用中，我们计划使用多学科方法来确定3-硝基苯甲酮(3-NBA)毒性的分子机制，3-NBA是一种常见的环境毒物。我们建议的指导性假设是，3-NBA可以形成加合物，在不干扰其结构的情况下增加DNA的稳定性。结果，这些损伤逃脱了NER的处理，持续存在于DNA中，并扩大了它们的毒性效应。我们将通过建立具有来自3-NBA的位点特定加合物的双链的溶液结构和热力学参数来验证我们的假设(目标2)，并建立它们在哺乳动物NER系统中的处理(目标3)。作为生物终点，我们将研究3-NBA加合物的诱变潜力，并建立哺乳动物细胞中跨损伤合成的机制(目标4)。化学合成是我们研究的基础，也是提案(目标1)的一个组成部分。通过化学合成，我们开发了这些加合物的制备方法，并将其特定地掺入2‘-寡核苷酸中。我们预计，我们的多学科方法将定义3-NBA毒性的相关机制，并反过来确定更好的环境暴露和疾病风险的生物标志物。 与公众健康相关：接触3-硝基苯并酮(3-NBA)是一种在煤炭和柴油燃烧过程中产生的环境遗传毒素，对人类健康是一种普遍的危害。3-NBA引起的DNA损伤可导致突变并启动致癌过程。这项研究将确定介导DNA中特定3-NBA损伤持续存在的结构、稳定性和修复机制，并确定它们的突变特性。

DESCRIPTION (provided by applicant): Cancer is a general term that refers to more than a hundred of different diseases characterized by uncontrolled cell division and the capacity of these cells to invade and destroy surrounding normal tissues. Etiologically, cancer is a slow developing condition affected by multiple factors including exposure to environmental toxics, lifestyle, viral infections and individual genetic makeup. Known factors that increase cancer risk include tobacco smoke, exposure to UV or ionizing radiation, and the intake of environmental toxicants present in the air, water or foods. Nitroarenes are widespread pollutants found in cigarette smoke, coal fly ash, and diesel exhaust. These compounds react with cellular DNA forming bulky base lesions that can cause gene mutations and eventually trigger carcinogenic processes. The nucleotide excision repair (NER) system opposes these effects by removing bulky DNA lesions and restoring genome integrity. Xeroderma Pigmentosum and Cockayne syndrome, two genetic diseases caused by NER deficiencies, are flagrant examples of the damaging consequences that the persistence of DNA lesions have for human health. In this application, we plan to use a multidisciplinary approach to determine the molecular mechanisms that mediate the toxicity of 3-nitrobenzanthrone (3-NBA), a prevalent environmental toxicant. The guiding hypothesis of our proposal is that 3-NBA can form adducts that increase DNA stability without perturbing its structure. As a result, these lesions escape NER processing, persisting in DNA and extending their toxic effects. We will test our hypothesis by establishing the solution structure and thermodynamic parameters of duplexes having site specific adducts derived from 3-NBA (aim 2) and establishing their processing by the mammalian NER system (aim 3). As biological end-point, we will investigate the mutagenic potential of 3-NBA adducts and establish the mechanisms of trans-lesion synthesis in mammalian cells (aim 4). Chemical synthesis by which we develop methods for the preparation and site-specific incorporation of these adducts into 2'- oligodeoxynucleotides, is the foundation of our studies and forms an integral part of the proposal (aim 1). We expect that our multidisciplinary approach will define the relevant mechanisms of 3- NBA toxicity and, in turn, identify better biomarkers of environmental exposure and disease risk. PUBLIC HEALTH RELEVANCE: Exposure to 3-nitrobenzanthrone (3-NBA), an environmental genotoxin produced during coal and diesel combustion, is a prevalent hazard for human health. DNA damage caused by 3-NBA can lead to mutations and initiate carcinogenic processes. This investigation will determine structural, stability and repair mechanisms that mediate the persistence of specific 3-NBA lesions in DNA and determine their mutagenic properties.