Kushida H, Fujita K, Suzuki A, Yamada M, Endo T, Nohmi T, Kamataki T
Laboratory of Drug Metabolism, Division of Pharmacobio-dynamics, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan.
Carcinogenesis. 2000 Jun;21(6):1227-32.
A Salmonella typhimurium tester strain YG7108 2E1/OR co-expressing human CYP2E1 together with human NADPH-cytochrome P450 reductase (OR) was established. The mutagen-activating capacity of human CYP2E1 for N-alkylnitrosamines was compared with that of CYP2A6 using the YG7108 2E1/OR and the YG7108 2A6/OR strains of SALMONELLA: Salmonella YG7108 2A6/OR is a derivative of YG7108 co-expressing CYP2A6 together with OR. Eight N-alkylnitrosamines, including N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), N-nitrosomethylphenylamine (NMPhA), N-nitrosopyrrolidine (NPYR), N-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were examined. CYP2E1 expressed in the YG7108 2E1/OR cells showed mutagen-activating capacity, as indicated by induced revertants/min/pmol cytochrome P450, for NDMA, NDEA, NDPA, NDBA, NPYR and NNK, but not NMPhA and NNN. CYP2A6 activated NDMA, NDEA, NDPA, NDBA, NMPhA, NPYR, NNN and NNK. The ratio of the mutagen-activating capacity seen with CYP2A6 to that seen with CYP2E1 was calculated for each N-alkylnitrosamine. In the case of NDMA, NPYR and NDEA, the ratio was under 1.0, while the ratio was over 1.0 with NDPA, NDBA, NNK, NMPhA and NNN. We conclude that human CYP2E1 is mainly responsible for the metabolic activation of N-nitrosamines with a relatively short alkyl chain(s), whereas CYP2A6 was predominantly responsible for the metabolic activation of N-alkylnitrosamines possessing a relatively bulky alkyl chain(s).
构建了一株共表达人细胞色素P450 2E1（CYP2E1）和人NADPH - 细胞色素P450还原酶（OR）的鼠伤寒沙门氏菌测试菌株YG7108 2E1/OR。利用沙门氏菌的YG7108 2E1/OR和YG7108 2A6/OR菌株，比较了人CYP2E1和CYP2A6对N - 烷基亚硝胺的诱变激活能力：沙门氏菌YG7108 2A6/OR是共表达CYP2A6和OR的YG7108的衍生物。检测了8种N - 烷基亚硝胺，包括N - 亚硝基二甲胺（NDMA）、N - 亚硝基二乙胺（NDEA）、N - 亚硝基二丙胺（NDPA）、N - 亚硝基二丁胺（NDBA）、N - 亚硝基甲基苯胺（NMPhA）、N - 亚硝基吡咯烷（NPYR）、N - 亚硝基去甲烟碱（NNN）和4 - （甲基亚硝胺基）-1 - （3 - 吡啶基）-1 - 丁酮（NNK）。YG7108 2E1/OR细胞中表达的CYP2E1对NDMA、NDEA、NDPA、NDBA、NPYR和NNK表现出诱变激活能力，以诱导回复突变体数/分钟/皮摩尔细胞色素P450表示，但对NMPhA和NNN无此能力。CYP2A6可激活NDMA、NDEA、NDPA、NDBA、NMPhA、NPYR、NNN和NNK。计算了每种N - 烷基亚硝胺的CYP2A6诱变激活能力与CYP2E1诱变激活能力的比值。对于NDMA、NPYR和NDEA，该比值小于1.0，而对于NDPA、NDBA、NNK、NMPhA和NNN，该比值大于1.0。我们得出结论，人CYP2E1主要负责具有相对短烷基链的N - 亚硝胺的代谢激活作用，而CYP2A6主要负责具有相对大烷基链的N - 烷基亚硝胺的代谢激活作用。
