PMID:17344335

Citation	Gonzalez-Covarrubias, V, Ghosh, D, Lakhman, SS, Pendyala, L and Blanco, JG (2007) A functional genetic polymorphism on human carbonyl reductase 1 (CBR1 V88I) impacts on catalytic activity and NADPH binding affinity. Drug Metab. Dispos. 35:973-80
Abstract	Human carbonyl reductase 1 (CBR1) metabolizes endogenous and xenobiotic substrates such as the fever mediator, prostaglandin E2 (PGE2), and the anticancer anthracycline drug, daunorubicin. We screened 33 CBR1 full-length cDNA samples from white and black liver donors and performed database analyses to identify genetic determinants of CBR1 activity. We pinpointed a single nucleotide polymorphism on CBR1 (CBR1 V88I) that encodes for a valine-to-isoleucine substitution for further characterization. We detected the CBR1 V88I polymorphism in DNA samples from individuals with African ancestry (p = 0.986, q = 0.014). Kinetic studies revealed that the CBR1 V88 and CBR1 I88 isoforms have different maximal velocities for daunorubicin (V(max) CBR1 V88, 181 +/- 13 versus V(max) CBR1 I88, 121 +/- 12 nmol/min . mg, p < 0.05) and PGE2 (V(max) CBR1 V88, 53 +/- 7 versus V(max) CBR1 I88, 35 +/- 4 nmol/min . mg, p < 0.01). Concomitantly, CBR1 V88 produced higher levels of the cardiotoxic metabolite daunorubicinol compared with CBR1 I88 (1.7-fold, p < 0.0001). Inhibition studies demonstrated that CBR1 V88 and CBR1 I88 are distinctively inhibited by the flavonoid, rutin (IC50 CBR1 V88, 54.0 +/- 0.4 microM versus IC50 CBR1 I88, 15.0 +/- 0.1 microM, p < 0.001). Furthermore, isothermal titration calorimetry analyses together with molecular modeling studies showed that CBR1 V88I results in CBR1 isoforms with different binding affinities for the cofactor NADPH (K(d) CBR1 V88, 6.3 +/- 0.6 microM versus K(d) CBR1 I88, 3.8 +/- 0.5 microM). These studies characterize the first functional genetic determinant of CBR1 activity toward relevant physiological and pharmacological substrates.
Links	PubMed PMC2442771 Online version:10.1124/dmd.107.014779
Keywords	Alcohol Oxidoreductases/antagonists & inhibitors; Alcohol Oxidoreductases/genetics; Alcohol Oxidoreductases/metabolism; Catalysis; Cloning, Molecular; DNA, Complementary/genetics; Daunorubicin/analogs & derivatives; Daunorubicin/metabolism; Genotype; Humans; Kinetics; Models, Molecular; NADP/metabolism; Polymorphism, Single Nucleotide; Rutin/pharmacology; Sequence Analysis, DNA
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