RESUMO
OBJECTIVE: The aim of this study was to investigate the influence of clinical and genetic factors on warfarin dose requirements in the Japanese population. METHODS: We enrolled 125 patients on stable warfarin anticoagulant therapy with an international normalized ratio maintained between 1.5 and 3.0. PCR-based methods were performed to analyze genetic polymorphisms in the genes pharmacokinetically and pharmacodynamically related to warfarin reactions, including cytochrome P450 (CYP) 2C9, vitamin K epoxide reductase complex subunit 1 (VKORC1), gamma-glutamyl carboxylase (GGCX) and factor VII (FVII). RESULTS: The presence of CYP2C9*3 and VKORC1-1639G>A had a significant impact on the mean maintenance dose of warfarin (CYP2C9*1/*1 2.74 +/- 1.24 mg/day vs. *1/*3 and *3/*3 1.56 +/- 0.85 mg/day, P = 0.009; VKORC1-1639AA 2.42 +/- 0.95 mg/day vs. GA 3.71 +/- 1.43 mg/day vs. GG 7.25 +/- 0.35 mg/day, P < 0.001). In the multiple linear regression model, the combination of age, body surface area, and genotypes of CYP2C9*3 and VKORC1-1639G>A explained 54.8% of the variance in warfarin dose requirements. CONCLUSIONS: The influences of CYP2C9*3 and VKORC1-1639G>A on the maintenance dose of warfarin were well-defined in Japanese patients, while polymorphisms of GGCX and FVII did not affect it. The model established in this study might provide us most likely individual maintenance dose based on clinical and genetic backgrounds.
Assuntos
Anticoagulantes/administração & dosagem , Inativação Metabólica/genética , Polimorfismo Genético/genética , Varfarina/administração & dosagem , Idoso , Anticoagulantes/farmacocinética , Hidrocarboneto de Aril Hidroxilases/genética , Carbono-Carbono Ligases/genética , Citocromo P-450 CYP2C9 , Fator VII/genética , Feminino , Genótipo , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Oxigenases de Função Mista/genética , Farmacogenética , Vitamina K Epóxido Redutases , Varfarina/farmacocinéticaRESUMO
Cytochrome P450 (CYP) 1A1 is involved in the metabolic activation of polycyclic aromatic hydrocarbons (PAHs) and is induced by several compounds, including PAHs. The induction of CYP1A1 mediated by the aryl hydrocarbon receptor (AhR) has been well investigated; however, little has been reported on the mechanisms of CYP1A1 induction mediated by factors other than AhR. In this study, we investigated the involvement of liver X receptor alpha (LXRα) in the induction of CYP1A1. TO-901317, an LXRα ligand, induced CYP1A1 mRNA in a dose-dependent fashion. Luciferase reporter assays using HepG2 cells showed that TO-901317 was capable of activating the promoter of the CYP1A1 gene and that a direct repeat 4 (DR4) motif located in a region from -452 to -467 was required for the induction of CYP1A1 through LXRα. Specific binding of LXRα to this DR4 motif was confirmed by gel shift and chromatin immunoprecipitation assays. Co-treatment of HepG2 cells with TO-901317 and 2,3,7,8-tetrachlorodibenzo-p-dioxin, a typical AhR ligand, caused the synergistic induction of CYP1A1 mRNA. Thus, we propose that the expression of CYP1A1 is regulated by LXRα as well as by AhR, suggesting that exposure to both LXRα and AhR ligands can result in the alteration of individual susceptibility to environmental carcinogens metabolically activated by CYP1A1.