Hyperglycemia-induced DNA damage as a driver of genomic instability

描述（由申请人提供）：肥胖结束了广泛的相关病理，包括高血糖、胰岛素抵抗、高脂血症和2型糖尿病，统称为代谢综合征。这种情况会显著增加患结肠癌、肝癌、胰腺癌、肾癌、乳腺癌、宫颈癌和子宫内膜癌的风险；然而，其机制尚不清楚。肥胖和2型糖尿病的许多病理并发症都是由高血糖和葡萄糖衍生的α-氧醛与蛋白质、脂质和DNA反应引起的晚期糖基化终产物（AGEs）的积累引起的。尽管蛋白质- ages在代谢性疾病中的病理后果已被认识多年，但DNA-AGE积累的程度及其在肥胖/糖尿病病理中的潜在作用在很大程度上尚未被探索。使用高灵敏度和确定性的质谱方法，我们已经表明，主要的DNA-AGE， CEdG，在人体组织中存在显著水平，其水平在代谢综合征的动物模型中相对于瘦血糖控制显著升高。我们最近发现，CEdG在人类细胞中具有诱变性，核苷酸切除修复（NER）是减少DNA-AGE诱导的基因组不稳定性的主要途径。由于肥胖和糖尿病导致NER下调，我们推测代谢综合征患者中诱变DNA-AGEs的积累大大提高了他们的癌症易感性。我们的长期目标是确定代谢性疾病中DNA-AGE水平升高如何导致基因组不稳定和癌症易感性增加。我们将验证高血糖诱导的诱变DNA- ages积累与DNA修复减弱一起推动基因组不稳定并大大增加癌症易感性的假设。我们认为，DNA-AGE积累和突变的组织特异性变异部分解释了与肥胖相关的癌症范围有限的原因。为了实现我们的长期目标，需要阐明主要DNA-AGEs的结构和化学稳定性，以确定最有可能导致体内基因组不稳定的产物（目的1）。为了研究肥胖中DNA-AGE的遗传毒性病理，我们将建立代谢综合征的动物模型，并测量组织特异性突变和DNA-AGE水平作为NER状态的函数（目的2）。为了更定量地定义由于代谢性疾病导致的DNA修复能力的下降，我们将使用从疾病进展阶段的肥胖/糖尿病小鼠制备的提取物来测量DNA- ages的修复动力学（目的3）。这些具体目标的成功实施将大大有助于我们理解癌症与肥胖病理后果引起的分子变化之间的联系。此外，我们预计提高我们对高血糖诱导的DNA-AGE病理的认识将对人类健康产生重大的整体影响，并刺激新疗法的发展，以降低与肥胖相关的特定癌症的风险。

DESCRIPTION (provided by applicant): Obesity endgenders a wide spectrum of interrelated pathologies including hyperglycemia, insulin resistance, hyperlipidemia, and Type 2 diabetes, collectively termed the metabolic syndrome. This condition significantly increases risk for cancers of the colon, liver, pancreas, kidney, breast, cervix, and endometrium; however, the mechanisms responsible remain unknown. Many pathological complications of obesity and Type 2 diabetes arise from hyperglycemia and the subsequent accumulation of advanced glycation end products (AGEs) resulting from reactions of glucose-derived α-oxo aldehydes with proteins, lipids, and DNA. Although the pathological consequences of protein-AGEs in metabolic disease have been recognized for many years, the extent of DNA-AGE accumulation and its potential role in obese/diabetic pathology are largely unexplored. Using a highly sensitive and determinative mass spectrometric method, we have shown that a major DNA-AGE, CEdG, is present at significant levels in human tissue, and its levels are substantially elevated in animl models of metabolic syndrome relative to lean euglycemic controls. We recently showed that CEdG is mutagenic in human cells, and that nucleotide excision repair (NER) is the major pathway for minimizing DNA-AGE induced genomic instability. Because NER is downregulated as consequence of adiposity and diabetes we theorize that the accumulation of mutagenic DNA-AGEs in individuals with metabolic syndrome substantially elevates their cancer susceptibility. Our long term goal is to determine how elevated DNA-AGE levels in metabolic disease contribute to genomic instability and increased vulnerability to cancer. We will test the hypothesis that hyperglycemia-induced accumulation of mutagenic DNA-AGEs in conjunction with attenuated DNA repair propels genomic instability and substantially increases cancer susceptibility. We propose that tissue-specific variations in DNA-AGE accumulation and mutagenesis account in part for the restricted range of cancers associated with obesity. Progress toward our long term goal requires elucidating the structures and chemical stabilities of the major DNA-AGEs in order to identify products most likely to contribute to genomic instability in vivo (Aim 1). To study the genotoxic pathology of DNA-AGEs in obesity, we will generate animal models of metabolic syndrome and measure tissue-specific mutations and DNA-AGE levels as a function of NER status (Aim 2). To more quantitatively define the decline in DNA repair capacity due to metabolic disease, we will measure the repair kinetics of DNA-AGEs using extracts prepared from obese/diabetic mice at progressive stages of disease (Aim 3). Successful implementation of these Specific Aims will contribute greatly toward our understanding of this link between cancer and a molecular change induced by a pathologic consequence of obesity. Moreover, we anticipate that enhancing our knowledge of hyperglycemia-induced DNA-AGE pathology will have a significant overall impact on human health and stimulate the development of novel treatments to reduce the risk of specific cancers associated with obesity.