Stiborová Marie, Sejbal Jan, Borek-Dohalská Lucie, Aimová Dagmar, Poljaková Jitka, Forsterová Kristina, Rupertová Martina, Wiesner Jirí, Hudecek Jirí, Wiessler Manfred, Frei Eva
Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
Cancer Res. 2004 Nov 15;64(22):8374-80. doi: 10.1158/0008-5472.CAN-04-2202.
Ellipticine is an antineoplastic agent, the mode of action of which is considered to be based on DNA intercalation and inhibition of topoisomerase II. We found that ellipticine also forms the cytochrome P450 (CYP)-mediated covalent DNA adducts. We now identified the ellipticine metabolites formed by human CYPs and elucidated the metabolites responsible for DNA binding. The 7-hydroxyellipticine, 9-hydroxyellipticine, 12-hydroxyellipticine, 13-hydroxyellipticine, and ellipticine N(2)-oxide are generated by hepatic microsomes from eight human donors. The role of specific CYPs in the oxidation of ellipticine and the role of the ellipticine metabolites in the formation of DNA adducts were investigated by correlating the levels of metabolites formed in each microsomal sample with CYP activities and with the levels of the ellipticine-derived deoxyguanosine adducts in DNA. On the basis of this analysis, formation of 9-hydroxyellipticine and 7-hydroxyellipticine was attributable to CYP1A1/2, whereas production of 13-hydroxyellipticine and ellipticine N(2)-oxide, the metabolites responsible for formation of two major DNA adducts, was attributable to CYP3A4. Using recombinant human enzymes, oxidation of ellipticine to 9-hydroxyellipticine and 7-hydroxyellipticine by CYP1A1/2 and to 13-hydroxyellipticine and N(2)-oxide by CYP3A4 was corroborated. Homologue modeling and docking of ellipticine to the CYP3A4 active center was used to explain the predominance of ellipticine oxidation by CYP3A4 to 13-hydroxyellipticine and N(2)-oxide.
椭圆玫瑰树碱是一种抗肿瘤药物，其作用方式被认为基于DNA嵌入和拓扑异构酶II的抑制。我们发现椭圆玫瑰树碱还能形成细胞色素P450（CYP）介导的共价DNA加合物。我们现已鉴定出由人CYP形成的椭圆玫瑰树碱代谢产物，并阐明了负责DNA结合的代谢产物。7-羟基椭圆玫瑰树碱、9-羟基椭圆玫瑰树碱、12-羟基椭圆玫瑰树碱、13-羟基椭圆玫瑰树碱和椭圆玫瑰树碱N(2)-氧化物由来自八名人类供体的肝微粒体产生。通过将每个微粒体样品中形成的代谢产物水平与CYP活性以及DNA中椭圆玫瑰树碱衍生的脱氧鸟苷加合物水平相关联，研究了特定CYP在椭圆玫瑰树碱氧化中的作用以及椭圆玫瑰树碱代谢产物在DNA加合物形成中的作用。基于此分析，9-羟基椭圆玫瑰树碱和7-羟基椭圆玫瑰树碱的形成归因于CYP1A1/2，而13-羟基椭圆玫瑰树碱和椭圆玫瑰树碱N(2)-氧化物（负责形成两种主要DNA加合物的代谢产物）的产生归因于CYP3A4。使用重组人酶证实了CYP1A1/2将椭圆玫瑰树碱氧化为9-羟基椭圆玫瑰树碱和7-羟基椭圆玫瑰树碱，以及CYP3A4将其氧化为13-羟基椭圆玫瑰树碱和N(2)-氧化物。利用椭圆玫瑰树碱与CYP3A4活性中心的同源建模和对接来解释CYP3A4将椭圆玫瑰树碱氧化为13-羟基椭圆玫瑰树碱和N(2)-氧化物的优势。
