Abstract
Variability in activity of CYP2C9, which is involved in the metabolism of approximately 15% of current therapeutic drugs, is an important contributor to interindividual differences in drug response. To evaluate the functional alternations of CYP2C9*2, CYP2C9*3, CYP2C9*8, CYP2C9*11 and CYP2C9*31, identified in our previous study in Chinese Han population, allelic variants as well as the wild-type CYP2C9 were transiently expressed in COS-7 cells. Kinetic parameters (Km, Vmax, and Clint) for S-warfarin 7-hydroxylation by these recombinant CYP2C9s were determined. Relative to CYP2C9.1, recombinant CYP2C9.3 and CYP2C9.11 exhibited significantly higher Km values, and all allelic variants showed significantly decreased Vmax and Clint values. Among all allelic variants, catalytic activity of CYP2C9.3 and CYP2C9.11 reduced the most (8.2% and 9.8% of Clint ratio, respectively; P < 0.001). These findings should be useful for predicting the phenotype profiles of CYP2C9 in Chinese Han population, comparing the functional results of these alleles accurately, and finally optimizing pharmacotherapy of drug treatment.
Highlights
Human cytochrome P450 2C9 (CYP2C9) is one of the most important members of the cytochrome P450 superfamily, accounting for ∼20% of hepatic total CYP content and involved in the metabolism of approximately 15% of current therapeutic drugs, including antibiotic, anticancer, antidiabetic, antiepileptic, antihypertensive, cannabinol, non-steroidal antiinflammatory, anticoagulant, and anti-hyperlipidemic drugs (Zhou et al, 2010). in addition, lots of endogenous compounds, such as progesterone, testosterone and arachidonic acid, are metabolized by CYP2C9 (Rifkind et al, 1995; Yamazaki and Shimada, 1997)
The wild type CYP2C9 and these five allelic variants identified in our previous study were expressed in COS-7 cells
We focused on five CYP2C9 alleles (CYP2C9∗2, CYP2C9∗3, CYP2C9∗8, CYP2C9∗11, and CYP2C9∗31) identified in Chinese Han population, expressed all of them as well as the wild type enzyme in COS-7 cells, and characterized their catalytic activity with S-warfarin as the representative substrate
Summary
Human cytochrome P450 2C9 (CYP2C9) is one of the most important members of the cytochrome P450 superfamily, accounting for ∼20% of hepatic total CYP content and involved in the metabolism of approximately 15% of current therapeutic drugs, including antibiotic, anticancer, antidiabetic, antiepileptic, antihypertensive, cannabinol, non-steroidal antiinflammatory, anticoagulant, and anti-hyperlipidemic drugs (Zhou et al, 2010). in addition, lots of endogenous compounds, such as progesterone, testosterone and arachidonic acid, are metabolized by CYP2C9 (Rifkind et al, 1995; Yamazaki and Shimada, 1997). Alternation of CYP2C9 activity is an important contributor to the interindividual differences in drug response. Patients carrying CYP2C9∗2 or CYP2C9∗3, both of which will lead to reduced enzymatic activity, were reported to have higher risk for adverse drug responses, when they were treated with warfarin or S-acenocoumarol (Higashi et al, 2002; Malhi et al, 2004; Visser et al, 2004). Different ethnic populations often show considerable differences in frequencies of CYP2C9 alleles. Functional characterization of different CYP2C9 variants, especially variants identified in the same ethnic population, is of great importance for the optimal pharmacotherapy of drug treatment, for the appropriate dosing of drugs with a narrow therapeutic index such as warfarin
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