THE ROLE OF CYTOCHROME P-450 ENZYMES IN CARCINOGENESIS

细胞色素P-450是酶的超家族，其中一些 能够代谢外源物质，如药物和 致癌物质以及内生菌，如类固醇和 前列腺素。在动物中，这些酶的多种形式是 同时表达的构成要素或之后 特定诱导剂的给药。这些酶显示 重叠的底物特性。因此，单个细胞色素P- 450可代谢多个底物和单个底物 可能受几种细胞色素P-450的作用。其中一些 细胞色素P-450催化产物与细胞结合 大分子，因此被推定为启动诱变 和致癌作用。为了定义一个给定的贡献 细胞色素P-450对特定药物代谢的影响 对于致癌物质，单独表达这些酶是很重要的。 为此，我们已经开始开发表达系统在 其中一个单独的细胞色素P-450蛋白是从 其全长cDNA.这一努力的成功将使我们能够 确定每一种酶对诱变的贡献 以及由化学致癌物介导的细胞转化。 为此，我们使用了两种类型的表达系统， 即重组痘苗病毒和重组逆转录病毒。 我们构建了具有感染性的重组痘苗病毒和 含有全长的传染性重组逆转录病毒 小鼠细胞色素P1-450和P3-的编码基因序列 450美元。感染重组人和小鼠细胞 病毒高水平表达真实大小的蛋白质为 通过免疫印迹检测。表达的蛋白质是 酶活性和显示的底物特异性 每种酶的特性。实验以实现 确定催化剂的专属性和贡献 酶的诱变正在进行中。

Cytochrome P-450s are a superfamily of enzymes, some of which are capable of metabolizing xenobiotics such as drugs and carcinogens as well as endobiotics such as steroids and prostaglandins. In animals, multiple forms of these enzymes are expressed simultaneously either constitutively or after administration of specific inducers. These enzymes display overlapping substrate specificities. Thus, a single cytochrome P- 450 may metabolize multiple substrates and a single substrate may be acted upon by several cytochrome P-450s. Some of the cytochrome P-450 catalytic products bind to cellular macromolecules and thus are presumed to initiate mutagenesis and carcinogenesis. In order to define the contribution of a given cytochrome P-450 to the metabolism of specific drugs and carcinogens, it is important to express these enzymes individually. For this purpose, we have begun to develop expression systems in which an individual cytochrome P-450 protein is synthesized from its full length cDNA. Success in this effort will enable us to define the contribution of each of these enzymes to mutagenesis and cell transformation mediated by chemical carcinogens. For this purpose, we employed two types of expression systems, namely recombinant vaccinia virus and recombinant retrovirus. We have constructed infectious recombinant vaccinia virus and infectious recombinant retrovirus containing the full length coding cDNA sequences for mouse cytochrome P1-450 and P3- 450. Human and mouse cells infected with the recombinant viruses expressed high levels of the authentic size proteins as detected by immunoblotting. The expressed proteins are enzymatically active and displayed substrate specificities characteristics of the respective enzymes. Experiments to determine the catalytic specificities and the contribution of the enzymes to mutagenesis are in progress.