title: Hepatic CYP2B6 expression: gender and ethnic differences and relationship to CYP2B6 genotype and CAR (constitutive androstane receptor) expression.
abstract: CYP2B6 metabolizes many drugs, and its expression varies greatly. CYP2B6 genotype-phenotype associations were determined using human livers that were biochemically phenotyped for CYP2B6 (mRNA, protein, and CYP2B6 activity), and genotyped for CYP2B6 coding and 5'-flanking regions. CYP2B6 expression differed significantly between sexes. Females had higher amounts of CYP2B6 mRNA (3.9-fold, P < 0.001), protein (1.7-fold, P < 0.009), and activity (1.6-fold, P < 0.05) than did male subjects. Furthermore, 7.1% of females and 20% of males were poor CYP2B6 metabolizers. Striking differences among different ethnic groups were observed: CYP2B6 activity was 3.6- and 5.0-fold higher in Hispanic females than in Caucasian (P < 0.022) or African-American females (P < 0.038). Ten single nucleotide polymorphisms (SNPs) in the CYP2B6 promoter and seven in the coding region were found, including a newly identified 13072A>G substitution that resulted in an Lys139Glu change. Many CYP2B6 splice variants (SV) were observed, and the most common variant lacked exons 4 to 6. A nonsynonymous SNP in exon 4 (15631G>T), which disrupted an exonic splicing enhancer, and a SNP 15582C>T in an intron-3 branch site were correlated with this SV. The extent to which CYP2B6 variation was a predictor of CYP2B6 activity varied according to sex and ethnicity. The 1459C>T SNP, which resulted in the Arg487Cys substitution, was associated with the lowest level of CYP2B6 activity in livers of females. The intron-3 15582C>T SNP (in significant linkage disequilibrium with a SNP in a putative hepatic nuclear factor 4 (HNF4) binding site) was correlated with lower CYP2B6 expression in females. In conclusion, we found several common SNPs that are associated with polymorphic CYP2B6 expression.
authors.affiliation: Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, 332 N. Lauderdale Street, Memphis, TN 38105, USA.
authors.forename: Vishal
authors.initials: V
authors.lastname: Lamba
authors.forename: Jatinder
authors.initials: J
authors.lastname: Lamba
authors.forename: Kazuto
authors.initials: K
authors.lastname: Yasuda
authors.forename: Stephen
authors.initials: S
authors.lastname: Strom
authors.forename: Julio
authors.initials: J
authors.lastname: Davila
authors.forename: Michael L
authors.initials: ML
authors.lastname: Hancock
authors.forename: James D
authors.initials: JD
authors.lastname: Fackenthal
authors.forename: Peter K
authors.initials: PK
authors.lastname: Rogan
authors.forename: Barbara
authors.initials: B
authors.lastname: Ring
authors.forename: Steven A
authors.initials: SA
authors.lastname: Wrighton
authors.forename: Erin G
authors.initials: EG
authors.lastname: Schuetz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis* / Q000235:genetics*; D001711:Biotransformation; D044383:Black People; D015153:Blotting, Western; D002648:Child; D002675:Child, Preschool; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D065702:Cytochrome P-450 CYP2B6; D005006:Ethnicity; D005260:Female; D008040:Genetic Linkage / Q000235:genetics; D006239:Haplotypes; D006630:Hispanic or Latino; D006801:Humans; D007223:Infant; D007438:Introns / Q000235:genetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D008617:Mephenytoin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics; D008862:Microsomes, Liver / Q000201:enzymology; D008875:Middle Aged; D008969:Molecular Sequence Data; D010089:Oxidoreductases, N-Demethylating / Q000096:biosynthesis* / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011991:Receptors, Virus / Q000096:biosynthesis* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012727:Sex Characteristics; D044465:White People; D001741:Black or African American
chemical_list: C568771:CLMP protein, human; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D012333:RNA, Messenger; D011991:Receptors, Virus; C014544:ethylphenylhydantoin; D001189:Aryl Hydrocarbon Hydroxylases; C585599:CYP2B6 protein, human; D065702:Cytochrome P-450 CYP2B6; D010089:Oxidoreductases, N-Demethylating; D008617:Mephenytoin