METABOLIC ACTIVATION OF N-HETEROCYCLIC AROMATICS

N-杂环芳烃的代谢激活

• 批准号: 3252214
• 负责人: DAVID WARSHAWSKY
• 金额: $ 17.22万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-08-01 至 1993-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3252214
• 关键词: DNA; acridines; adduct; affinity chromatography; benzopyrenes; carbazoles; chemical binding; chemical carcinogen; chemical carcinogenesis; chemical fingerprinting; chemical structure function; covalent bond; environment related neoplasm /cancer; environmental contamination; enzyme induction /repression; halobiphenyl /halotriphenyl compound; heterocyclic polycyclic compound; high performance liquid chromatography; laboratory mouse; laboratory rat; liver cells; liver metabolism; lung; microsomes; mutagens; nucleotide metabolism; skin; tissue /cell culture; toxin metabolism

N-heterocyclic aromatics are environmentally important pollutants, however, little is known of their mechanism of action or biological effects. The objective is to investigate the metabolic activation of 7H-dibenz(c,g)carbazole (DBC) which is a potent carcinogen in mouse lung, liver, and skin, with respect to dibenz(a,j)acridine (DBA) a moderate to weak carcinogen in mouse lung and skin. Since the structural difference between the well characterized polycyclic aromatic hydrocarbons and the N-heterocyclic analogs is the existence of a nitrogen atom in the aromatic ring system of the latter, it is hypothesized that any differences in metabolism, metabolic activation, DNA binding, or carcinogenic potency is due not only to the presence of a nitrogen atom but to the aromaticity of the heteroatom containing ring. The specific aims involve the characterization of the metabolic activation and DNA binding of DBC and DBA in mouse skin and liver as follows: 1) determine the modulation of metabolism of DBC and DBA incubated with liver preparations using a variety of inducing agents, 2) determine the modulation of DNA binding of DBC and DBA with induced liver preparations, 3) determine the modulation of metabolism of DBC and DBA with induced skin preparations, 4) characterize the covalent binding of selected metabolites of DBC and DBA to DNA in vitro with liver preparations, 5) characterize the covalent binding of DBC and DBA to DNA in skin and liver in vivo and 6) undertake chronic dose response carcinogenicity studies for DBC and DBA relative to benzo(a)pyrene and mixtures thereof. Phenobarbital, Aroclor 1254, DBC, DBA and 3-methylcholanthrene will be used for enzyme induction and subcellular liver and skin fractions will be prepared. Metabolism of DBC and DBA will be analyzed by HPLC and alumina column chromatography. In vitro DNA binding and DNA adducts (as standards) will be analyzed by radiometry, HPLC, and analytical techniques. In vivo studies will involve the development of finger prints of DNA adducts using (32)P-postlabeling techniques and dephosphorylation of the adducts for comparison with in vitro adducts. Lastly, analysis of the biological responses of mixtures will determine whether additive, synergistic or inhibitory effects are involved. This approach will provide valuable information concerning the disposition of an important class of carcinogens and will lead to a better understanding of the mechanism(s) of action of N-heterocyclic aromatic carcinogenesis.

N-杂环芳烃是对环境重要的污染物，然而， 人们对它们的作用机制或生物效应知之甚少。这 目的是研究代谢激活 7H-二苯并(c,g)咔唑(DBC)是小鼠肺部的强致癌物， 肝脏和皮肤，相对于二苯并(a,j)吖啶 (DBA) 而言，中等至 对小鼠肺和皮肤有弱致癌作用。由于结构差异 良好表征的多环芳烃和 N-杂环类似物是芳香族中存在氮原子 后者的环系统，假设任何差异 代谢、代谢激活、DNA 结合或致癌效力 不仅因为氮原子的存在，还因为其芳香性 含杂原子的环。具体目标包括 DBC 和 DBA 代谢激活和 DNA 结合的表征 在小鼠皮肤和肝脏中如下：1)确定 使用各种方法与肝脏制剂一起孵育 DBC 和 DBA 的代谢 诱导剂，2) 确定 DBC 和 DNA 结合的调节 DBA 使用诱导肝制剂，3) 确定调节 DBC 和 DBA 与诱导皮肤制剂的代谢，4) 表征 DBC 和 DBA 选定代谢物与 DNA 的体外共价结合 与肝脏制剂，5) 表征 DBC 和的共价结合 DBA对体内皮肤和肝脏中的DNA进行慢性剂量反应6) DBC 和 DBA 相对于苯并 (a) 芘和 它们的混合物。苯巴比妥、Aroclor 1254、DBC、DBA 和 3-甲基胆蒽将用于酶诱导和亚细胞 将制备肝脏和皮肤部分。 DBC和DBA的代谢会 通过HPLC和氧化铝柱色谱法进行分析。体外 DNA 结合 DNA 加合物（作为标准）将通过辐射测定法、HPLC 和 分析技术。体内研究将涉及开发 使用 (32)P-后标记技术的 DNA 加合物的指纹图谱 加合物的去磷酸化以与体外加合物进行比较。 最后，对混合物的生物反应的分析将确定 是否涉及累加、协同或抑制作用。这 方法将提供有关处置的宝贵信息 重要的一类致癌物，将有助于更好地了解 N-杂环芳香族致癌作用机制。