A New CYP2A6 Gene Deletion Responsible for the In Vivo Polymorphic Metabolism of (+)-cis-3,5-Dimethyl-2-(3-pyridyl)thiazolidin-4-one Hydrochloride in Humans

• Published in: The Journal of pharmacology and experimental therapeutics 1999-04, Vol.289 (1), p.437-442
• Main Authors: Nunoya, K I, Yokoi, T, Kimura, K, Kainuma, T, Satoh, K, Kinoshita, M, Kamataki, T
• Format: Article
• Language: English
• Subjects: Adult; Alleles; Aryl Hydrocarbon Hydroxylases; Base Sequence; Blotting, Southern; Cytochrome P-450 CYP2A6; Cytochrome P-450 Enzyme System - genetics; Deoxyribonucleases, Type II Site-Specific - genetics; DNA - genetics; DNA - isolation & purification; Exons; Gene Library; Humans; Leukocytes - metabolism; Male; Mixed Function Oxygenases - genetics; Molecular Sequence Data; Phenotype; Platelet Aggregation Inhibitors - blood; Platelet Aggregation Inhibitors - metabolism; Platelet Aggregation Inhibitors - urine; Polymorphism, Restriction Fragment Length; Reverse Transcriptase Polymerase Chain Reaction; Sequence Deletion; Thiazoles - blood; Thiazoles - metabolism; Thiazoles - urine; Thiazolidines
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1016/S0022-3565(24)38154-6

(+)- Cis -3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride (SM-12502) is a newly developed drug as a platelet-activating factor receptor antagonist. The disposition of SM-12502 was investigated in plasma from 28 healthy Japanese volunteers after a single i.v. administration of SM-12502. Three of 28 subjects were phenotyped as poor metabolizers (PMs). Genomic DNAs from three extensive metabolizers or three PMs of SM-12502 were analyzed by Southern blot analysis with CYP2A6 cDNA as a probe. DNAs from three PMs digested with Sac I and Sph I showed novel restriction fragment length polymorphisms (RFLPs); one type without 4.5- and 2.6-kb fragments and a weak density of a 6.4-kb fragment (E-type), and the other type without 7.1- and 5.5-kb restriction fragments (C′-type) as compared with three extensive metabolizers, respectively. The deletional restriction fragments specific to three PMs in Sac I- and Sph I-RFLPs were identified as CYP2A6 . Using polymerase chain reaction-RFLP analyses of the gene from the three PMs, we found that the exon 1, exon 8, and exon 9 in CYP2A6 were absent. A new RFLP characterized by Sac I and Sph I was found to be due to the entire gene deletion of the three exons and was associated with the decreased metabolism of SM-12502. This study demonstrates a new deletional allele in the human CYP2A6 gene responsible for the poor metabolic phenotype of SM-12502.