Mechanistic role of P4501 enzymes in the prevention of PAH carcinogenesis by omega 3 fatty acids

项目总结 细胞色素P450是参与药物代谢和生物激活的主要酶。这很好 已知几种CYP酶将omega-3脂肪酸代谢成其环氧代谢物，从而抑制 血管生成、肿瘤生长和转移。大量的多环芳烃(PAH)是人类 致癌物质。PAH-DNA加合物可能会导致DNA损伤和关键基因的突变，最终导致 致癌。PAH-DNA加合物水平与肿瘤发病率之间的显著正向线性回归 是在我们实验室的动物实验中观察到的。我们还发现omega-3脂肪酸 二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)抑制细胞色素P1B1、EZH2、DNMT3a、miR17、 MiR19b-1可显著降低肺和肝组织PAH-DNA加合物，降低肿瘤发生率。这个 这一应用的中心假设是omega 3-脂肪酸及其环氧代谢物将减弱 抑制PAH-DNA加合物形成的多种致癌机制 可能通过调控表观遗传基因来调节细胞色素P450，以及抑制肿瘤的发生 (例如，EZH2、DNMT3a、MIR-17、MIR-19b-1)。我们提出了以下具体目标。目标1：测试 细胞色素P4501A1和细胞色素P1B1在预防小鼠多环芳烃致癌中的作用机制假说 与CO饮食相比，在EPA、DHA或EPA DHA饮食中保持，然后暴露于 对这些小鼠进行降压作用机理的研究。目的2：验证小鼠缺乏可溶性物质的假设 环氧化物水解酶(SEH)对EPA/DHA介导的PAH的保护作用强于WT小鼠 致癌，因为sEH已知能迅速水解环氧代谢物，如17，18-环氧二十碳四烯酸 血清和组织中的二十二碳五烯酸(EEQ)和19，20-环氧二十二碳五烯酸(EDP)与非活性代谢物有关。在……里面 在一些实验中，我们将使用特定的sEH抑制剂t-TUCB或一种新的t-TUCB样抑制剂来治疗WT小鼠 (这可能很快就会进入人类临床试验)，随后是用EPA/DHA和BP治疗小鼠。目标3： 为了验证内源性omega-3脂肪酸，特别是它们的环氧代谢物将发挥作用的假设 在体内多环芳烃预防肺癌发生中的关键作用，并且存在机制联系 在CyP1和sEH之间。脂肪-1转基因(Fat-1-TG)小鼠，将内源性omega-6脂肪转化为 酸(富含CO)转化为omega-3脂肪酸，并降低omega-6/omega-3的比率，将用于 学习。我们还将创建Fat-1-TG/sEH缺失小鼠，以探索CyP1和sEH 酶有助于omega-3脂肪酸介导的多环芳烃致癌的预防。如果我们的假设是 CyP1和sEH酶在omega-3脂肪酸中起重要作用，即EPA/DHA介导的预防 事实证明，PAH诱导的癌症是正确的，那么它将在目前对 人类癌症预防。如果成功，拟议的研究将导致饮食中的新机制 对多环芳烃诱发肺癌的干预措施。

PROJECT SUMMARY The cytochrome P450s (CYPs) are the major enzymes involved in drug metabolism and bioactivation. It is well known that several CYP enzymes metabolize omega-3 fatty acids to their epoxy metabolites that inhibit angiogenesis, tumor growth, and metastasis. Numerous polycyclic aromatic hydrocarbons (PAH) are human carcinogens. PAH-DNA adducts may lead to DNA damage and mutations in critical genes, eventually leading to cancer. A significant positive linear regression between levels of PAH-DNA adducts and tumor incidence was observed in animal experiments in our laboratory. We also discovered that omega-3 fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) inhibited CYP1B1, EZH2, DNMT3a, miR 17, miR19b-1 and significantly decreased pulmonary and hepatic PAH-DNA adducts, and tumor incidence. The central hypothesis of this application is that omega 3-fatty acids and their epoxy metabolites will attenuate pulmonary carcinogenesis by multiple mechanisms entailing attenuation of PAH-DNA adduct formation by modulating CYPs, as well as by suppression of tumorigenesis, probably via modulation of epigenetic genes (e.g., EZH2, DNMT3a, miR-17, miR-19b-1). We propose the following Specific Aims. Aim 1: To test the hypothesis that CYP1A1 and CYP1B1 play mechanistic roles in prevention of PAH carcinogenesis in mice maintained on EPA, DHA, or EPA + DHA diets, compared to those on a CO diet, followed by exposure of these mice to BP for the study of the mechanisms. Aim 2: To test the hypothesis that mice deficient in soluble epoxide hydrolase (sEH) will confer more protection than WT mice to EPA/DHA-mediated prevention of PAH carcinogenesis, as sEH is known to rapidly hydrolyze epoxy metabolites such as 17,18-epoxy eicosatetraenoic acid (EEQ) and 19,20-epoxy docosapentaenoic acids (EDP) in serum and tissues to inactive metabolites. In some experiments, we will treat WT mice with the specific sEH inhibitor, t-TUCB, or a new t-TUCB-like inhibitor (that is likely to go to human clinical trials soon), followed by treatment of mice with EPA/DHA and BP. Aim 3: To test the hypothesis that endogenous omega-3 fatty acids, especially their epoxy metabolites, will play a pivotal role in the prevention of pulmonary carcinogenesis by PAHs in vivo, and that there is a mechanistic link between CYP1, and sEH. Fat-1-transgenic (Fat-1-Tg) mice, which will convert endogenous omega-6 fatty acids (rich in CO) into omega-3 fatty acids and decrease the ratios of omega-6/omega-3, will be used in this study. We will also create Fat-1-Tg/sEH-null mice for exploring the mechanisms by which CYP1 and sEH enzymes contribute to omega-3 fatty acid-mediated prevention of PAH carcinogenesis. If our hypothesis that CYP1 and sEH enzymes play important roles in omega-3 fatty acids, i.e. EPA/DHA-mediated prevention of PAH-induced cancers turns out to be correct, then it will break new grounds in the current understanding of human cancer prevention. If successful, the proposed studies should lead to novel mechanisms in dietary interventions against lung cancers induced by PAHs.