title: Substrate-dependent functional alterations of seven CYP2C9 variants found in Japanese subjects.
abstract: CYP2C9 is a polymorphic enzyme that metabolizes a number of clinically important drugs. In this study, catalytic activities of seven alleles found in Japanese individuals, CYP2C9*3 (I359L), *13 (L90P), *26 (T130R), *28 (Q214L), *30 (A477T), *33 (R132Q), and *34 (R335Q), were assessed using three substrates (diclofenac, losartan, and glimepiride). When expressed in a baculovirus-insect cell system, the holo and total (apo and holo) CYP2C9 protein expression levels were similar among the wild type (CYP2C9.1) and six variants except for CYP2C9.13. A large part of CYP2C9.13 was present in the apo form P420. Compared with CYP2C9.1, all variants except for CYP2C9.34 exhibited substrate-dependent changes in K(m), V(max), and intrinsic clearance (V(max)/K(m)). For diclofenac 4'-hydroxylation, the intrinsic clearance was decreased markedly (by >80%) in CYP2C9.13, CYP2C9.30, and CYP2C9.33 and variably (63-76%) in CYP2C9.3, CYP2C9.26, and CYP2C9.28 due to increased K(m) and/or decreased V(max) values. For losartan oxidation, CYP2C9.13 and CYP2C9.28 showed 2.5- and 1.8-fold higher K(m) values, respectively, and all variants except for CYP2C9.34 showed >77% lower V(max) and intrinsic clearance values. For glimepiride hydroxylation, the K(m) of CYP2C9.13 was increased 7-fold, and the V(max) values of all variants significantly decreased, resulting in reductions in the intrinsic clearance by >80% in CYP2C9.3, CYP2C9.13, CYP2C9.26, and CYP2C9.33 and by 56 to 75% in CYP2C9.28 and CYP2C9.30. These findings suggest the necessity for careful administration of losartan and glimepiride to patients bearing these six alleles.
authors.affiliation: Division of Functional Biochemistry and Genomics, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan. maekawa@nihs.go.jp
authors.forename: Keiko
authors.initials: K
authors.lastname: Maekawa
authors.forename: Noriko
authors.initials: N
authors.lastname: Harakawa
authors.forename: Emiko
authors.initials: E
authors.lastname: Sugiyama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tohkin
authors.forename: Su-Ryang
authors.initials: SR
authors.lastname: Kim
authors.forename: Nahoko
authors.initials: N
authors.lastname: Kaniwa
authors.forename: Noriko
authors.initials: N
authors.lastname: Katori
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Hasegawa
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yasuda
authors.forename: Kei
authors.initials: K
authors.lastname: Kamide
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Miyata
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Sawada
mesh_terms: D000483:Alleles; D047228:Angiotensin II Type 1 Receptor Blockers / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism*; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004008:Diclofenac / Q000378:metabolism; D014644:Genetic Variation; D006801:Humans; D007004:Hypoglycemic Agents / Q000378:metabolism; D007313:Insecta; D007564:Japan; D007700:Kinetics; D019808:Losartan / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity; D013453:Sulfonylurea Compounds / Q000378:metabolism
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D018076:DNA, Complementary; D007004:Hypoglycemic Agents; D011994:Recombinant Proteins; D013453:Sulfonylurea Compounds; C400322:cytochrome P-450 CYP2C subfamily; D004008:Diclofenac; C057619:glimepiride; D003577:Cytochrome P-450 Enzyme System; D019808:Losartan