title: Relationship between CES2 genetic variations and rifampicin metabolism.
abstract: OBJECTIVE
  Rifampicin is known to be deacetylated in vivo, resulting in its metabolite 25-desacetyl rifampicin, but the enzyme metabolizing rifampicin and the association of this process with any genetic variation have not yet been elucidated. In this study, genetic variations of a surrogate enzyme, carboxylesterase 2 (CES2), and their association with the metabolism of this drug, were investigated.
  
  
  METHODS
  Plasma concentrations of rifampicin and 25-desacetyl rifampicin were measured in 35 patients with tuberculosis receiving a first-line antituberculosis treatment. Direct PCR-based sequencing of the CES2 gene, covering all 12 exons, the 5'-untranslated region (UTR), the 3'-UTR and intronic and promoter regions, was performed. A dual luciferase reporter assay was carried out to assess whether variations in the promoter region affected the transcription of this gene.
  
  
  RESULTS
  Ten variations were detected, of which two were in the candidate promoter region, five in introns and three in the 3'-UTR. One of the variations in the 3'-UTR was a novel variation. Genotypes at three closely linked variations (c.-2263A > G, c.269-965A > G and c.1612 + 136G > A) and c.1872*302_304delGAA were associated with significantly different plasma rifampicin concentrations. The mean plasma rifampicin concentration significantly increased with the number of risk alleles at the three closely linked variations, while the plasma concentration decreased along with an increase in the number of risk alleles at c.1872*302_304delGAA. When HepG2 cells were transfected with a luciferase reporter construct bearing the c.-2263G allele, luciferase activities were consistently decreased (by 5%-10%) compared with those harbouring the c.-2263A sequence.
  
  
  CONCLUSIONS
  Variations in CES2, especially c.-2263A > G in the promoter region, may alter rifampicin metabolism by affecting expression of the gene.
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Song
authors.forename: Ho Eun
authors.initials: HE
authors.lastname: Chang
authors.forename: Sun Hee
authors.initials: SH
authors.lastname: Jun
authors.forename: Kyoung Un
authors.initials: KU
authors.lastname: Park
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Eun-Mi
authors.initials: EM
authors.lastname: Lee
authors.forename: Young-Han
authors.initials: YH
authors.lastname: Song
authors.forename: Junghan
authors.initials: J
authors.lastname: Song
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000483:Alleles; D000900:Anti-Bacterial Agents / Q000097:blood / Q000378:metabolism*; D044466:Asian People; D043182:Carboxylesterase / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D003640:Dealkylation; D005787:Gene Frequency; D014644:Genetic Variation; D006801:Humans; D008156:Luciferases / Q000235:genetics; D013058:Mass Spectrometry; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics; D012293:Rifampin / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D000900:Anti-Bacterial Agents; D008156:Luciferases; C517204:CES2 protein, human; D043182:Carboxylesterase; C032393:25-deacetylrifampicin; D012293:Rifampin
keywords: carboxylesterase 2; pharmacogenetics; promoters; tuberculosis