Chemical markers of heterocyclic aromatic amines for human biomonitoring

描述(申请人提供)：前列腺癌是美国男性中最常见的恶性肿瘤，也是与癌症相关的死亡的第二大原因。确定这种疾病的风险因素并制定预防战略至关重要。一些流行病学研究报告称，经常食用熟肉，含有杂环芳胺(HAA)2-氨基-1-甲基-6-苯基咪唑并[4，5-b]吡啶(PhIP)，与前列腺癌风险有关。PhIP是一种强有力的啮齿动物前列腺癌致癌物，它会导致氧化应激、腺泡萎缩和前列腺炎症。这些都是人类前列腺癌发生的关键特征。已经提出了一个范例，说明食用含有PhIP(和其他HAAs)的熟肉在前列腺癌病因学中的因果作用；然而，缺乏暴露和DNA损伤的生物标记物来验证这一模型。我们的长期目标是通过使用化学标记物来评估HAAs构成的癌症风险，这些化学标记物可以区分不同风险水平的个体。在这次资助续期中，我们的目标是评估膳食中PhIP的暴露及其与其他HA、肉类遗传毒物和细胞中产生的内源性亲电体之间的关系，通过使用基于质谱学(MS)的方法来测量遗传毒物并识别其在前列腺中DNA损伤的生物标志物。我们将在经常食用熟肉的非裔美国人和高加索男性良性前列腺增生症或前列腺癌患者的队列中实施我们最近建立的哈斯和其他熟肉基因毒物及其DNA加合产品的生物标志物。在目标1中，将通过测量头发中累积的HAA来评估HAA暴露；将通过不同的MS扫描方法在前列腺中检测HAA、其他肉类遗传毒物和内源性亲电体的DNA加合物。目的2)福尔马林固定的石蜡包埋的前列腺组织，一种在生物监测DNA损伤方面未得到充分利用的生物样品，将被用于在接受前列腺切除术的受试者中筛选HAA-DNA加合物。加合物水平将与当前非特异性免疫组织化学技术获得的值进行比较。还将实施MS方法来测量PhIP-血清白蛋白加合物作为生物有效剂量的长期生物标记物。在目标3)中，我们将对与致癌物代谢有关的编码酶的基因进行高密度基因分型，这些酶可能会影响前列腺中的DNA损伤。前列腺的HAA-DNA加合物水平与头发中的HAA水平相关；前列腺中的HAA和其他DNA加合物的水平将与影响生物活性的I、II相异源代谢酶的基因型相关。我们的发现将提供DNA损伤的直接测量，并评估HAAs、其他熟肉遗传毒物和内源性亲电体对前列腺DNA遗传损伤的相对贡献。

DESCRIPTION (provided by applicant): Prostate cancer is the most frequently diagnosed malignancy and second leading cause of cancer-related death among men in the United States. Identifying risk factors of this disease and developing strategies for prevention are critical. A number of epidemiologic studies have reported an association between frequent consumption of well-done cooked meats, containing the heterocyclic aromatic amine (HAA) 2-amino-1-methyl- 6-phenylimidazo[4,5-b]pyridine (PhIP) and prostate cancer risk. PhIP is a potent rodent prostate carcinogen, and it induces oxidative stress, atrophy of the acini, and inflammation of the prostate. These are critical features that occur in human prostate carcinogenesis. A paradigm has been put forth for a causal role of consumption of well-done cooked meats containing PhIP (and other HAAs) in the etiology of prostate cancer; however, biomarkers of exposure and DNA damage are lacking to validate this model. Our long-term goal is to assess the cancer risk posed by HAAs, by employing chemical markers that may distinguish individuals at different levels of risk. In this grant renewal, our objective is to assess dietary exposure to PhIP and its potential to induce damage to DNA in the prostate in relation to other HAAs, meat genotoxicants, and endogenous electrophiles produced in the cell, by employing mass spectrometric (MS)- based methods to measure genotoxicants and identify their biomarkers of DNA damage in the prostate. We will implement our recently established biomarkers of HAAs and other cooked meat genotoxicants and their DNA adduction products in cohorts of African American and Caucasian men with benign prostate hyper- plasia or prostate cancer who frequently eat well-done cooked meat. In Aim 1) HAA exposure will be assessed by measurement of HAAs accrued in hair; DNA adducts of HAAs, other meat genotoxicants, and endogenous electrophiles, will be determined by different MS scanning methods, in prostate. In Aim 2) Formalin-fixed paraffin embedded prostate tissue, an underutilized biospecimen in biomonitoring DNA damage, will be employed to screen for HAA-DNA adducts in subjects undergoing prostatectomy. Adduct levels will be compared to those values obtained by current but non-specific immunohistochemical techniques. MS methods will also be implemented to measure PhIP-serum albumin adducts as long-lived biomarkers of the biologically effective dose. In Aim 3) we will conduct high density genotyping of genes encoding enzymes involved carcinogen metabolism that may impact DNA damage in the prostate. Prostate HAA-DNA adduct levels will be correlated to HAA levels in hair; the levels of HAA and other DNA adducts in prostate will be correlated to genotypes of phase I and II xenobiotic metabolism enzymes, which impact biological activity. Our findings will provide direct measurement of DNA damage and assess the relative contribution of HAAs, other cooked meat genotoxicants and endogenous electrophiles to the genetic damage of DNA in the prostate.