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-杂环芳香剂是环境上重要的污染物，但是 对它们的作用机理或生物学作用知之甚少。这 目的是研究 7H-dibenz（C，G）甲Bazole（DBC）是小鼠肺中有效的致癌物 肝脏和皮肤，相对于Dibenz（A，J）accridine（DBA） 小鼠肺和皮肤中的致癌物弱。由于结构差异 在表征良好的多环芳烃和 n-杂环类似物是芳香族中的氮原子的存在 后者的戒指系统，可以假设 代谢，代谢激活，DNA结合或致癌效力为 不仅是由于存在氮原子，还因为 包含环的杂原子。具体目的涉及 DBC和DBA的代谢激活和DNA结合的表征 如下所示，在小鼠皮肤和肝脏中：1）确定调制 DBC和DBA的代谢与肝脏制剂一起使用一种品种 诱导剂，2）确定DNA结合的调节DBC和 DBA具有诱导的肝脏制剂，3）确定调制 DBC和DBA具有诱导皮肤制剂的代谢，4）特征 选定的DBC和DBA代谢产物与DNA的共价结合在体外与DNA 使用肝脏制剂，5）表征了DBC的共价结合和 DBA至体内皮肤和肝脏中的DNA，6）进行慢性剂量反应 DBC和DBA的致癌性研究相对于Benzo（A）Pyrene和 混合物。苯巴比妥，Aroclor 1254，DBC，DBA和DBA 3-甲基胆碱将用于酶诱导和亚细胞 将准备肝脏和皮肤分数。 DBC和DBA的代谢将 可以通过HPLC和氧化铝柱色谱分析。体外DNA结合 和DNA加合物（标准）将通过辐射测定法，HPLC和 分析技术。体内研究将涉及 使用（32）p孔标签技术的DNA加合物的指纹和 加合物的去磷酸化，以与体外加合物进行比较。 最后，分析混合物的生物学反应将决定 涉及添加剂，协同作用还是抑制作用。这 方法将提供有关处置的宝贵信息 重要类的致癌物，并会更好地理解 N杂环芳香族癌变的作用机制。