title: Evaluation of amino acid-mustard transport as L-type amino acid transporter 1 (LAT1)-mediated alkylating agents.
abstract: The L-type amino acid transporter 1 (LAT1, SLC7A5) is an Na+-independent neutral amino acid transporter the expression of which is located in retinal endothelial cells. Due to its broad substrate selectivity, LAT1 has been proposed to mediate the transport of amino acid-related drugs across the blood-tissue barriers. Here, we have investigated the transport screening of amino acid-mustards using a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB2) which expresses LAT1. We synthesized 5 amino acid-mustards: tyrosine-mustard, phenylglycine-mustard, alanine-mustard, ornithine-mustard, and lysine-mustard. LAT1-mediated [3H]L-phenylalanine (Phe) uptake by TR-iBRB2 cells was inhibited in a competitive manner by tyrosine-mustard and phenylglycine-mustard as well as melphalan (phenylalanine-mustard). Phenylglycine-mustard was able to induce the efflux of [3H]Phe preloaded into the TR-iBRB2 cells expressing LAT1 through the obligatory exchange mechanism, although tyrosine-mustard, alanine-mustard, ornithine-mustard, lysine-mustard, and melphalan did not induce any significant efflux. These findings suggest that phenylglycine-mustard is a better substrate for LAT1 than melphalan and other amino acid-mustards.
authors.affiliation: Department of Pharmaceutics, University of Toyama, Toyama, Japan. hosoyak@pha.u-toyama.ac.jp
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Hosoya
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kyoko
authors.forename: Naoki
authors.initials: N
authors.lastname: Toyooka
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kato
authors.forename: Masahiro
authors.initials: M
authors.lastname: Orihashi
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Tomi
authors.forename: Masanori
authors.initials: M
authors.lastname: Tachikawa
mesh_terms: D000596:Amino Acids / Q000378:metabolism / Q000493:pharmacokinetics* / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D027283:Large Neutral Amino Acid-Transporter 1 / Q000378:metabolism*; D009150:Mustard Compounds / Q000378:metabolism / Q000493:pharmacokinetics*; D011485:Protein Binding; D051381:Rats; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D000596:Amino Acids; D027283:Large Neutral Amino Acid-Transporter 1; D009150:Mustard Compounds