Developmental study for effective high-through-put screening system for new drug registration

利用表达人细胞色素P450的基因工程鼠伤寒沙门氏菌YG7108细胞和人NADPH-细胞色素P450还原酶(OR)，用Ames试验检测了细胞色素P450在N-烷基亚硝胺代谢活化中的作用。评价了N-烷基亚硝胺的结构与参与活化的CyP形式(S)之间的关系。11株表达不同形式细胞色素P450的鼠伤寒沙门氏菌YG7108细胞(细胞色素P1A1、细胞色素P1A2、细胞色素P1B1、细胞色素P2A6、细胞色素P2C8、细胞色素P2C9、细胞色素P2C19、细胞色素P2D6、细胞色素P3A1、细胞色素P3A4和细胞色素P3A5)。8种N-烷基亚硝胺这些N-烷基亚硝胺主要被细胞色素P450_2E_1、细胞色素P_2A_6和细胞色素P450_1A1激活。根据诱变剂的产生能力判断，烷基相对较短的N-烷基亚硝胺，如NDMA和NMEA，主要被CYP2E1激活。随着烷基链碳原子数的增加，CYP2A6的贡献增大。CYP2A6在NDEA、NDPA、NMPA、NMBA和NEBA的激活中起主要作用。有趣的是，CYP1A1成为CYP的一种分子形式，在NDBA的代谢激活中发挥着重要作用。

The role of human cytochrome P450 (CYP) in the metabolic activation of N-alkylnitrosamines was examined by Ames test using genetically engineered Salmonella typhimurium (S. typhimurium)YG7108 cells expressing each form of human CYP together with human NADPH-cytochrome P450 reductase (OR). The relationship between the structure of N-alkylnitrosamines and CYP form(s) involved in the activation was evaluated. Eleven strains of S. typhimurium YG7108 cells expressing each form of CYP (CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 or CYP3A5) were employed. Eight N-alkylnitrosamines These N-alkylnitrosamines were mainly activated by CYP2E1, CYP2A6 and CYP1A1. N-alkylnitrosamines with relatively short alkyl chains such as NDMA and NMEA were primarily activated by CYP2E1 as judged by mutagen-producing capacity. With the increase of the number of the carbon atoms of the alkyl chains, the contribution of CYP2A6 increased. CYP2A6 played major roles in the activation of NDEA, NDPA, NMPA, NMBA and NEBA. Interestingly, CYP1A1 became a molecular form of CYP playing a major role in the metabolic activation of NDBA.