Substrate-dependent functional alterations of seven CYP2C9 variants found in Japanese subjects.
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.
Maekawa
Keiko
K
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
Harakawa
Noriko
N
Sugiyama
Emiko
E
Tohkin
Masahiro
M
Kim
Su-Ryang
SR
Kaniwa
Nahoko
N
Katori
Noriko
N
Hasegawa
Ryuichi
R
Yasuda
Kazuki
K
Kamide
Kei
K
Miyata
Toshiyuki
T
Saito
Yoshiro
Y
Sawada
Jun-ichi
J
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
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