title: Organic cation transporters OCT1 and OCT2 determine the accumulation of lamivudine in CD4 cells of HIV-infected patients.
abstract: OBJECTIVE
  Identifying factors that determine concentrations of antiretroviral drugs in CD4 cells are important for improving therapeutic efficacy. Experimental models indicate that the nucleoside reverse transcriptase inhibitor lamivudine is transported by the organic cation transporters 1 and 2 (OCT1 and OCT2, respectively). Here, we tested whether OCT1 and OCT2 contribute to the uptake of lamivudine into native CD4 cells of human immunodeficiency virus (HIV)-infected individuals.
  
  
  METHODS
  CD4 cells obtained by non-activated cell sorting from 35 individuals with HIV-1 infection were incubated with lamivudine (10 μM, 30 min), and intracellular concentrations of lamivudine and its active metabolite lamivudine triphosphate were determined by liquid chromatography tandem mass spectrometry. The expression of OCT1 and OCT2 mRNA was measured by quantitative real-time polymerase chain reaction (PCR). A model of OCT2-transfected CD4 cells was established for mechanistic investigations.
  
  
  RESULTS
  Intracellular concentrations of lamivudine and its active metabolite lamivudine triphosphate showed strong linear correlations with each other and with the CD4 mRNA expression of OCT1 and OCT2 (r > 0.80). Coincubation with protease inhibitors (ritonavir, nelfinavir) that inhibit OCT1 and OCT2 yielded decreased intracellular concentrations of lamivudine and lamivudine triphosphate. Incubation of CD4 cells from healthy donors transfected with an OCT2 expression vector yielded increased concentrations of lamivudine and lamivudine triphosphate.
  
  
  CONCLUSIONS
  Our studies indicate a role of OCT1 and OCT2 for the cellular accumulation of lamivudine in HIV-infected individuals.
authors.affiliation: First Department of Internal Medicine, Medical Hospital of the University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany. norma.jung@uk-koeln.de
authors.forename: N
authors.initials: N
authors.lastname: Jung
authors.forename: C
authors.initials: C
authors.lastname: Lehmann
authors.forename: A
authors.initials: A
authors.lastname: Rubbert
authors.forename: E
authors.initials: E
authors.lastname: Schömig
authors.forename: G
authors.initials: G
authors.lastname: Fätkenheuer
authors.forename: P
authors.initials: P
authors.lastname: Hartmann
authors.forename: D
authors.initials: D
authors.lastname: Taubert
mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D003570:Cytidine Triphosphate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D054306:Dideoxynucleotides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics; D015497:HIV-1 / Q000187:drug effects; D006801:Humans; D019259:Lamivudine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D019888:Nelfinavir / Q000494:pharmacology; D027701:Organic Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D027702:Organic Cation Transporter 1 / Q000235:genetics / Q000378:metabolism*; D000075102:Organic Cation Transporter 2; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D019438:Ritonavir / Q000494:pharmacology; D053719:Tandem Mass Spectrometry; D014162:Transfection; D055815:Young Adult
chemical_list: D054306:Dideoxynucleotides; D017320:HIV Protease Inhibitors; D027701:Organic Cation Transport Proteins; D027702:Organic Cation Transporter 1; D000075102:Organic Cation Transporter 2; D012333:RNA, Messenger; C491013:SLC22A2 protein, human; C417268:lamivudine triphosphate; D019259:Lamivudine; D003570:Cytidine Triphosphate; D019888:Nelfinavir; D019438:Ritonavir