Molecular Mechanisms of Nitroarene Toxicity

描述（由申请人提供）：癌症是一个总称，指的是一百多种不同的疾病，其特征是细胞分裂失控，这些细胞有能力侵入和破坏周围的正常组织。从病因上讲，癌症是一种缓慢发展的疾病，受多种因素的影响，包括暴露于环境有毒物质、生活方式、病毒感染和个人基因构成。已知增加癌症风险的因素包括吸烟、暴露于紫外线或电离辐射以及摄入空气、水或食物中的环境有毒物质。硝基芳烃是广泛存在于香烟烟雾、煤灰和柴油废气中的污染物。这些化合物与细胞DNA发生反应，形成巨大的碱基损伤，导致基因突变，最终引发致癌过程。核苷酸切除修复（NER）系统通过去除大体积DNA损伤和恢复基因组完整性来对抗这些影响。色素性干皮病和柯凯因综合症这两种由缺碘化钠引起的遗传病，就是DNA损伤持续存在对人类健康造成破坏性后果的明证。在本应用中，我们计划采用多学科方法来确定介导3-硝基苯并蒽酮（3-NBA）毒性的分子机制，这是一种普遍存在的环境毒物。我们的建议的指导假设是，3-NBA可以形成加合物，增加DNA的稳定性，而不会扰乱其结构。结果，这些病变逃脱了NER的处理，在DNA中持续存在并扩大其毒性作用。我们将通过建立从3- nba衍生的具有位点特异性加合物的双链化合物的溶液结构和热力学参数（目标2）以及建立哺乳动物NER系统对其的处理（目标3）来验证我们的假设。作为生物学终点，我们将研究3-NBA加合物的致突变潜力，并建立哺乳动物细胞中跨病变合成的机制（目的4）。化学合成是我们研究的基础，也是提案的组成部分（目标1）。通过化学合成，我们开发了制备方法和将这些加合物结合到2'-寡脱氧核苷酸中的位点特异性方法。我们期望我们的多学科方法将定义3- NBA毒性的相关机制，进而确定环境暴露和疾病风险的更好的生物标志物。

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.