RT Journal Article
SR Electronic
T1 Interaction of Halogenated Tyrosine/Phenylalanine Derivatives with Organic Anion Transporter 1 in the Renal Handling of Tumor Imaging Probes
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 451
OP 462
DO 10.1124/jpet.120.000235
VO 375
IS 3
A1 Jin, Chunhuan
A1 Wei, Ling
A1 Ohgaki, Ryuichi
A1 Tominaga, Hideyuki
A1 Xu, Minhui
A1 Okuda, Suguru
A1 Okanishi, Hiroki
A1 Kawamoto, Yasuharu
A1 He, Xin
A1 Nagamori, Shushi
A1 Kanai, Yoshikatsu
YR 2020
UL http://jpet.aspetjournals.org/content/375/3/451.abstract
AB Halogenated tyrosine/phenylalanine derivatives have been developed for use in tumor imaging and targeted alpha therapy. 3-Fluoro-α-methyl-l-tyrosine (FAMT), targeting amino acid transporter LAT1 (SLC7A5), is a cancer-specific positron emission tomography probe that exhibits high renal accumulation, which is supposed to be mediated by organic anion transporter OAT1 (SLC22A6). In the present study, we investigated the structural requirements of FAMT essential for interaction with OAT1. OAT1 transported FAMT with a Km of 171.9 μM. In structure-activity relationship analyses, removal of either the 3-halogen or 4-hydroxyl group from FAMT or its structural analog 3-iodo-α-methyl-l-tyrosine greatly decreased the interaction with OAT1, reducing the [14C]p-aminohippurate uptake inhibition and the efflux induction. By contrast, the α-methyl group, which is essential for LAT1 specificity, contributed to a lesser degree. In fluorinated tyrosine derivatives, fluorine at any position was accepted by OAT1 when there was a hydroxyl group at the ortho-position, whereas ortho-fluorine was less interactive when a hydroxyl group was at meta- or para-positions. The replacement of the ortho-fluorine with a bulky iodine atom greatly increased the interaction. In in vivo studies, probenecid decreased the renal accumulation (P < 0.001) and urinary excretion (P = 0.0012) of FAMT, whereas the plasma concentration was increased, suggesting the involvement of OAT1-mediated transepithelial organic anion excretion. LAT1-specific 2-fluoro-α-methyltyrosine, which had lower affinity for OAT1, exhibited lower renal accumulation (P = 0.0142) and higher tumor uptake (P = 0.0192) compared with FAMT. These results would provide a basis to design tumor-specific compounds that can avoid renal accumulation for tumor imaging and targeted alpha therapy.SIGNIFICANCE STATEMENT We revealed the structural characteristics of halogenated tyrosine derivatives essential for interaction with the organic anion transporter responsible for their renal accumulation. We have confirmed that such interactions are important for renal handling and tumor uptake. The critical contribution of hydroxyl and halogen groups and their positions as well as the role of α-methyl group found in the present study may facilitate the development of tumor-specific compounds while avoiding renal accumulation for use in tumor imaging and targeted alpha therapy.