Chemical markers of heterocyclic aromatic amines for human biomonitoring

描述（由申请人提供）：前列腺癌是美国男性中最常诊断的恶性肿瘤，也是癌症相关死亡的第二大原因。确定这种疾病的风险因素和制定预防战略至关重要。许多流行病学研究报告了经常食用煮熟的熟肉（含有杂环芳香胺（HAA）2-氨基-1-甲基-6-苯基咪唑[4，5-B]吡啶（PhIP））与前列腺癌风险之间的关联。PhIP是一种有效的啮齿动物前列腺致癌物，它诱导氧化应激、腺泡萎缩和前列腺炎症。这些都是发生在人类前列腺癌的关键特征。已经提出了一个范式，消费的因果关系的作用，煮熟的熟肉含有PhIP（和其他哈斯）的前列腺癌的病因，但是，缺乏暴露和DNA损伤的生物标志物来验证这个模型。 我们的长期目标是通过使用可以区分不同风险水平的个体的化学标记物来评估哈斯造成的癌症风险。在这次资助更新中，我们的目标是评估饮食暴露于PhIP及其诱导前列腺DNA损伤的潜力，与其他哈斯，肉类遗传毒物和细胞中产生的内源性亲电体有关，通过采用基于质谱（MS）的方法测量遗传毒物并确定其前列腺DNA损伤的生物标志物。 我们将在患有良性前列腺增生或前列腺癌的非洲裔美国人和白人男性队列中实施我们最近建立的哈斯和其他熟肉遗传毒物及其DNA内收产物的生物标志物，这些男性经常吃熟透的熟肉。目的1）通过测量毛发中累积的哈斯来评估HAA暴露;通过不同的MS扫描方法测定前列腺中哈斯、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损伤中未充分利用的生物标本，将用于筛选接受前列腺切除术的受试者中的HAA-DNA加合物。将加合物水平与通过当前但非特异性免疫组织化学技术获得的值进行比较。还将采用MS方法测量PhIP-血清白蛋白加合物作为生物有效剂量的长寿命生物标志物。在目标3）中，我们将对编码可能影响前列腺DNA损伤的致癌物代谢酶的基因进行高密度基因分型。前列腺HAA-DNA加合物水平将与毛发中的HAA水平相关;前列腺中的HAA和其他DNA加合物水平将与影响生物活性的I期和II期异生物质代谢酶的基因型相关。 我们的研究结果将提供直接测量的DNA损伤和评估的相对贡献的哈斯，其他熟肉遗传毒物和内源性亲电体的DNA在前列腺的遗传损伤。

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.