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，慢性炎症和感染导致恶性细胞转化，从而在人类癌症的病因中发挥关键作用。随着慢性感染和细胞炎症而产生过量的自由基(碳酸盐、二氧化氮、超氧自由基)，这些自由基与脂膜中的多不饱和脂肪酸(PUFA)反应，产生高活性、遗传毒性的氧基中间体(过氧基和烷氧基)。反过来，这些自由基通过不明确的途径导致氧化性DNA损伤，从而导致癌症的病因。鸟嘌呤是DNA中最容易氧化的核酸碱基，因此是活性自由基物种攻击的主要目标。形成的鸟嘌呤自由基经历一系列反应，最终形成稳定和不稳定的、具有遗传毒性的化学最终产物。然而，对这些反应途径，特别是过氧基和烷氧基与DNA的反应机理还知之甚少。我们开发了一种新的方法来实时研究DNA中不稳定的碱基自由基与水溶液中的活性中间体，如脂质过氧化产生的过氧基和烷氧基的反应。通过对中间产物和最终反应产物的分析，包括高效液相色谱、MALDI-TOF/MS和高效液相-电喷雾串联质谱仪，将有助于深入了解DNA反应和氧化途径的机理。在具体目标1中，我们将研究DNA中多不饱和脂肪酸过氧基和鸟嘌呤自由基的自由基-自由基反应机理。在具体目标2中，将评估8-氧鸟嘌呤的多不饱和脂肪酸过氧基引发的进一步氧化，这是一种普遍存在的众所周知的细胞DNA氧化损伤形式。在具体目标3中，将研究多不饱和脂肪酸分子与活性氧物种(碳酸盐自由基、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生与慢性炎症和感染有关。更好地了解DNA损伤的氧化脂质过氧化途径将为开发预防和/或进展这些类型的恶性肿瘤的新策略提供合理的基础。

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.