title: A mutation in the drug transporter gene ABCC2 associated with impaired methotrexate elimination.
abstract: Human multidrug resistance protein 2 (MRP2, encoded by ABCC2) is involved in active efflux of anionic drugs such as methotrexate. MRP2 is expressed on the luminal side of hepatocytes and renal proximal tubular cells, indicating an important role in drug elimination. We postulated that loss-of-function mutations in ABCC2, which are involved in the Dubin-Johnson syndrome, may be associated with impaired methotrexate elimination and an increased risk of toxicity. We studied the biological phenotype and ABCC2 coding sequence in a patient receiving a high-dose methotrexate infusion for large B-cell lymphoma and who had an unusual pharmacokinetic profile, mainly characterized by a three-fold reduction in the methotrexate elimination rate. This resulted in severe methotrexate over-dosing and reversible nephrotoxicity. An inversion of the urinary coproporphyrin isomer I/III ratio (a specific biological marker of the Dubin-Johnson syndrome) was observed in this patient. Genetic analysis of ABCC2 identified a heterozygous mutation replacing a highly conserved arginine by glycine in the cytoplasmic part of the second membrane-spanning domain (position 412 of MRP2), a region associated with substrate affinity. This genetic variant was not found in a control population. Functional analysis in transiently transfected Chinese hamster ovary cells revealed a loss of transport activity of the G412 MRP2 mutant protein. An ABCC2 mutation altering MRP2-mediated methotrexate transport and resulting in impaired drug elimination and subsequent renal toxicity was identified. Candidates for methotrexate therapy should be considered for MRP2 functional testing.
authors.affiliation: Department of Pharmacology, Pitié-Salpêtrière University Hospital, Assistance Publique-Hôpitaux de Paris, Pierre et Marie Curie University, Paris, France. jean-sebastien.hulot@psl.ap-hop-paris.fr
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Hulot
authors.forename: Eric
authors.initials: E
authors.lastname: Villard
authors.forename: Ange
authors.initials: A
authors.lastname: Maguy
authors.forename: Véronique
authors.initials: V
authors.lastname: Morel
authors.forename: Lluis
authors.initials: L
authors.lastname: Mir
authors.forename: Isabelle
authors.initials: I
authors.lastname: Tostivint
authors.forename: Demiana
authors.initials: D
authors.lastname: William-Faltaos
authors.forename: Christine
authors.initials: C
authors.lastname: Fernandez
authors.forename: Stéphane
authors.initials: S
authors.lastname: Hatem
authors.forename: Gilbert
authors.initials: G
authors.lastname: Deray
authors.forename: Michel
authors.initials: M
authors.lastname: Komajda
authors.forename: Véronique
authors.initials: V
authors.lastname: Leblond
authors.forename: Philippe
authors.initials: P
authors.lastname: Lechat
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000009:adverse effects / Q000378:metabolism / Q000493:pharmacokinetics*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004252:DNA Mutational Analysis; D006801:Humans; D008223:Lymphoma / Q000235:genetics* / Q000378:metabolism; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D008727:Methotrexate / Q000009:adverse effects / Q000378:metabolism / Q000493:pharmacokinetics*; D008875:Middle Aged; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics*; D009154:Mutation
chemical_list: D000964:Antimetabolites, Antineoplastic; D026901:Membrane Transport Proteins; D008727:Methotrexate; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C000715087:ABCC2 protein, human