title: Transport of lamivudine [(-)-beta-L-2',3'-dideoxy-3'-thiacytidine] and high-affinity interaction of nucleoside reverse transcriptase inhibitors with human organic cation transporters 1, 2, and 3.
abstract: Nucleoside reverse transcriptase inhibitors (NRTIs) need to enter cells to act against the HIV-1. Human organic cation transporters (hOCT1-3) are expressed and active in CD4+ T cells, the main target of HIV-1, and have been associated with antiviral uptake in different tissues. In this study, we examined whether NRTIs interact and are substrates of hOCT in cells stably expressing these transporters. Using [(3)H]N-methyl-4-phenylpyridinium, we found a high-affinity interaction among abacavir [[(1S,4R)-4-[2-amino-6-(cyclopropylamino)purin-9-yl]-cyclopent-2-enyl]methanol sulfate] (ABC); <0.08 nM], azidothymidine [3'-azido-3'-deoxythymidine (AZT); <0.4 nM], tenofovir disoproxil fumarate (<1.0 nM), and emtricitabine (<2.5 nM) and hOCTs. Using a wide range of concentrations of lamivudine [(-)-beta-L-2',3'-dideoxy-3'-thiacyitidine (3TC)], we determined two different binding sites for hOCTs: a high-affinity site (K(d1) = 12.3-15.4 pM) and a low-affinity site (K(d2) = 1.9-3.4 mM). Measuring direct uptake of [(3)H]3TC and inhibition with hOCT substrates, we identified 3TC as a novel substrate for hOCT1, 2, and 3, with hOCT1 as the most efficient transporter (K(m) = 1.25 +/- 0.1 mM; V(max) = 10.40 +/- 0.32 nmol/mg protein/min; V(max)/K(m) = 8.32 +/- 0.40 microl/mg protein/min). In drug-drug interaction experiments, we analyzed cis-inhibition of [(3)H]3TC uptake by ABC and AZT and found that 40 to 50% was inhibited at low concentrations of the drugs (K(i) = 22-500 pM). These data reveal that NRTIs experience a high-affinity interaction with hOCTs, suggesting a putative role for these drugs as modulators of hOCT activity. Finally, 3TC is a novel substrate for hOCTs and the inhibition of its uptake at low concentrations of ABC and AZT could have implications for the pharmacokinetics of 3TC.
authors.affiliation: IrsiCaixa Foundation, Hospital Germans Trias i Pujol, E-08916, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Gerard
authors.initials: G
authors.lastname: Minuesa
authors.forename: Christopher
authors.initials: C
authors.lastname: Volk
authors.forename: Míriam
authors.initials: M
authors.lastname: Molina-Arcas
authors.forename: Valentin
authors.initials: V
authors.lastname: Gorboulev
authors.forename: Itziar
authors.initials: I
authors.lastname: Erkizia
authors.forename: Petra
authors.initials: P
authors.lastname: Arndt
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Clotet
authors.forename: Marçal
authors.initials: M
authors.lastname: Pastor-Anglada
authors.forename: Hermann
authors.initials: H
authors.lastname: Koepsell
authors.forename: Javier
authors.initials: J
authors.lastname: Martinez-Picado
mesh_terms: D000818:Animals; D019380:Anti-HIV Agents / Q000378:metabolism*; D001665:Binding Sites / Q000187:drug effects; D001693:Biological Transport, Active / Q000187:drug effects; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D015224:Dideoxynucleosides / Q000378:metabolism; D004347:Drug Interactions; D006801:Humans; D007700:Kinetics; D019259:Lamivudine / Q000378:metabolism*; D027362:Organic Anion Transport Protein 1 / Q000378:metabolism*; D029362:Organic Anion Transporters, Sodium-Independent / Q000378:metabolism*; D018894:Reverse Transcriptase Inhibitors / Q000378:metabolism*; D014162:Transfection; D015215:Zidovudine / Q000378:metabolism; D000099227:Abacavir
chemical_list: D019380:Anti-HIV Agents; D015224:Dideoxynucleosides; D019259:Lamivudine; D027362:Organic Anion Transport Protein 1; D029362:Organic Anion Transporters, Sodium-Independent; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D000099227:Abacavir; C490280:SLC22A7 protein, human; C114338:organic anion transport protein 3