PT - JOURNAL ARTICLE AU - Minuesa, Gerard AU - Volk, Christopher AU - Molina-Arcas, Míriam AU - Gorboulev, Valentin AU - Erkizia, Itziar AU - Arndt, Petra AU - Clotet, Bonaventura AU - Pastor-Anglada, Marçal AU - Koepsell, Hermann AU - Martinez-Picado, Javier TI - Transport of Lamivudine [(-)-β-<span class="sc">l</span>-2′,3′-Dideoxy-3′-thiacytidine] and High-Affinity Interaction of Nucleoside Reverse Transcriptase Inhibitors with Human Organic Cation Transporters 1, 2, and 3 AID - 10.1124/jpet.108.146225 DP - 2009 Apr 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 252--261 VI - 329 IP - 1 4099 - http://jpet.aspetjournals.org/content/329/1/252.short 4100 - http://jpet.aspetjournals.org/content/329/1/252.full SO - J Pharmacol Exp Ther2009 Apr 01; 329 AB - 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 [3H]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); &lt;0.08 nM], azidothymidine [3′-azido-3′-deoxythymidine (AZT); &lt;0.4 nM], tenofovir disoproxil fumarate (&lt;1.0 nM), and emtricitabine (&lt;2.5 nM) and hOCTs. Using a wide range of concentrations of lamivudine [(-)-β-l-2′,3′-dideoxy-3′-thiacyitidine (3TC)], we determined two different binding sites for hOCTs: a high-affinity site (Kd1 = 12.3–15.4 pM) and a low-affinity site (Kd2 = 1.9–3.4 mM). Measuring direct uptake of [3H]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 (Km = 1.25 ± 0.1 mM; Vmax = 10.40 ± 0.32 nmol/mg protein/min; Vmax/Km = 8.32 ± 0.40 μl/mg protein/min). In drug-drug interaction experiments, we analyzed cis-inhibition of [3H]3TC uptake by ABC and AZT and found that 40 to 50% was inhibited at low concentrations of the drugs (Ki = 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. The American Society for Pharmacology and Experimental Therapeutics