GENETICS OF AFLATOXIN METABOLISM ROLE IN CARCINOGENESIS

这项建议代表了我们对黄曲霉毒素和 细胞色素P-450。研究的重点是以下几个初步步骤 黄曲霉毒素B1(AFB1)致癌作用包括：(A)激活和 不同细胞色素P-450对黄曲霉毒素B_1的失活作用； 这些细胞色素P-450的遗传调控；(C)对 参与抑制的遗传和分子机制 细胞色素在多阶段肝癌发生中的作用；和(D)研究 细胞色素之间关系的分子和遗传基础 黄曲霉毒素B_1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隔离以发展 分子探针(cDNA、基因组DNA)。这些分子探测器将是 表征并用于阐明：(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 不同的途径；和(B)基因和分子改变 诱导细胞色素P-450在多阶段肝癌发生过程中的抑制。 大部分工作将在大鼠体内进行，并在体外进行 标记黄曲霉毒素，细菌诱变系统，RNA，DNA和 大鼠细胞色素P-450的分离。须使用的特定方法 包括：放射化学方法、高压液相色谱、 生化和酶学方法，超速离心法，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.