GENETICS OF AFLATOXIN METABOLISM ROLE IN CARCINOGENESIS

这项建议是我们对黄曲霉毒素研究的延续， 细胞色素P-450。 研究的重点是以下初步步骤： 黄曲霉毒素B1（AFB 1）致癌作用包括：（a）激活和 通过各种细胞色素P-450使AFB 1失活;（B）阐明 这些细胞色素P-450的遗传调控;（c）研究 基因和分子机制参与的镇压， 多阶段肝癌发生过程中的细胞色素;和（d）调查 细胞色素之间关系的分子和遗传基础 黄曲霉毒素B1对P-450的抑制和诱导肝癌的发生。 多种细胞色素P-450参与黄曲霉毒素B_1的优先代谢 通过激活和失活途径将被分离， 分子探针（cDNA，基因组DNA）。 这些分子探针将被 其特征在于并用于阐明：（a）分子基础 不同细胞色素P-450在黄曲霉毒素B_1代谢中的区域选择性 各种途径;和（B）所需的遗传和分子改变， 在多阶段肝癌发生过程中诱导细胞色素P-450抑制。 大部分工作将在大鼠体内和体外进行， 标记的黄曲霉毒素，细菌诱变系统，RNA，DNA，和 细胞色素P-450。 使用的特定方法 包括：放射化学方法，高压液相色谱法， 生化和酶学方法，超离心，杂交瘤和 重组DNA技术。

This proposal represents a continuation of our studies on aflatoxins and cytochromes P-450. The focus of the studies is on the initial steps of aflatoxin B1 (AFB1) carcinogenesis including: (a) activation and deactivation of AFB1 by various cytochromes P-450; (b) elucidation of the genetic regulation of these cytochromes P-450; (c) investigation of the genetic and molecular mechanisms involved in the repression of the cytochromes during multistage hepatocarcinogenesis; and (d) investigation of the molecular and genetic bases of the relationship between cytochromes P-450 repression and induction of hepatocarcinogenesis by AFB1. Various cytochromes P-450 involved in the preferential metabolism of AFB1 via activation and deactivation pathways will be isolated to develop molecular probes (cDNA, genomic DNA). These molecular probes will be characterized and used to elucidate: (a) molecular basis of regioselectivity of various cytochromes P-450 in the metabolism of AFB1 via various pathways; and (b) genetic and molecular alterations required to induce cytochromes P-450 repression during multistage hepatocarcinogenesis. Much of the work will be performed in vivo in rats and in vitro with labeled aflatoxins, bacterial mutagenesis systems, RNA, DNA, and cytochromes P-450 isolated from rats. Particular methods to be used include: radiochemical methods, high pressure liquid chromatography, biochemical and enzymologic methods, ultra-centrifugation, hybridoma and recombinant DNA techniques.