Reaction pathways of lipid oxyl radicals and DNA damage

描述（由申请人提供）：越来越多的流行病学数据表明，慢性炎症和感染诱导恶性细胞转化，因此在人类癌症的病因学中起关键作用。慢性感染和细胞炎症导致自由基（碳酸根、二氧化氮、超氧自由基）过量产生，并伴随着这些自由基与脂膜中的多不饱和脂肪酸（PUFA）反应，产生高反应性、遗传毒性的氧自由基中间体（过氧化氢和烷氧基自由基）。反过来，这些自由基有助于氧化DNA损伤，这有助于通过不明确的途径导致癌症的病因。鸟嘌呤是DNA中最容易氧化的核酸碱基，因此是反应性自由基物质攻击的主要目标。形成的鸟嘌呤自由基经历级联反应，最终形成稳定和不稳定的遗传毒性化学终产物。然而，反应途径，特别是过氧基和烷氧基自由基与DNA的反应机理知之甚少。我们已经开发了新的方法来研究在真实的时间的反应，不稳定的核碱基自由基在DNA与活性中间体，如过氧化氢和烷氧基自由基来自脂质过氧化反应，在水溶液中。通过包括HPLC、MALDI-TOF/MS和HPLC-ESI-MS/MS在内的复杂分析方法对中间体和最终反应产物进行分析，将为深入了解DNA反应和氧化途径的机制提供帮助。在具体目标1中，将研究DNA中PUFA过氧自由基和鸟嘌呤自由基的自由基-自由基反应的机理。在具体目标2中，将评估由8-氧代鸟嘌呤的PUFA过氧自由基引发的进一步氧化，8-氧代鸟嘌呤是一种普遍存在且众所周知的细胞氧化DNA损伤形式。在具体目标3中，将研究PUFA分子与活性氧（碳酸根阴离子、二氧化氮、超氧自由基）的氧化途径的详细机制。包括肝细胞癌、前列腺癌、胰腺癌、肾细胞癌和结肠癌在内的多种癌症的发展与慢性炎症和感染相关。更好地了解氧化脂质过氧化途径的DNA损伤应该提供一个合理的基础，为预防和/或发展这些类型的恶性肿瘤的新策略的发展。

DESCRIPTION (provided by applicant): A growing body of epidemiological data suggests that chronic inflammation and infection induce malignant cell transformations and thus play a critical role in the etiology of human cancers. The overproduction of radicals (carbonate, nitrogen dioxide, superoxide radicals) in response to chronic infection and cellular inflammation is accompanied by the reactions of these radicals with polyunsaturated fatty acids (PUFA) in lipid membranes that generate highly reactive, genotoxic oxyl intermediates (peroxyl and alkoxyl radicals). In turn, these radicals contribute to oxidative DNA damage that contributes to the etiology of cancer by poorly defined pathways. Guanine is the most easily oxidizable nucleic acid base in DNA and is therefore a primary target of attack of reactive radical species. The guanine radicals formed undergo a cascade of reactions that culminate in the formation of stable and unstable, genotoxic chemical end-products. However, the reaction pathways, particularly the mechanisms of reaction of peroxyl and alkoxyl radicals with DNA are poorly understood. We have developed new approaches for studying in real time the reactions of unstable nucleobase radicals in DNA with reactive intermediates such as the peroxyl and alkoxyl radicals derived from lipid peroxidation, in aqueous solutions. The analysis of intermediate and final reaction products by a complex of analytical methods including HPLC, MALDI-TOF/MS, and HPLC-ESI-MS/MS, will provide insights into the mechanism of DNA reaction and oxidation pathways. In specific Aim 1, the mechanisms of radical-radical reactions of PUFA peroxyl radicals and guanine radicals in DNA will be investigated. In specific Aim 2, the further oxidation initiated by PUFA peroxyl radicals of 8-oxoguanine, a ubiquitous and well known form of cellular oxidative DNA damage, will be assessed. In specific Aim 3, the detailed mechanisms of the still poorly understood oxidation pathways of PUFA molecules with reactive oxygen species (carbonate radical anion, nitrogen dioxide, superoxide radicals) will be investigated. The development of a variety of cancers including hepatocellular carcinoma, prostate cancer, pancreatic cancer, renal cell carcinoma, and colon cancer, have been correlated with chronic inflammation and infection. A better understanding of the oxidative lipid peroxidation pathways of DNA damage should provide a rational basis for the development of new strategies for the prevention and/or progression of these types of malignancies.