title: Structural determinants of arylacetic acid nonsteroidal anti-inflammatory drugs necessary for binding and activation of the prostaglandin D2 receptor CRTH2.
abstract: The chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) receptor, a G protein-coupled receptor that mediates chemotaxis of inflammatory cells in response to prostaglandin D2 (PGD2), is hypothesized to play a role in Th2-mediated allergic disease. In addition to PGD2, CRTH2 can be activated by indomethacin, a nonselective cyclooxygenase inhibitor and widely used nonsteroidal anti-inflammatory drug (NSAID). To evaluate the structural features that confer CRTH2 binding selectivity, structure-activity relationship analysis of arylacetic acid class NSAIDs as CRTH2 receptor ligands was performed. Indomethacin, sulindac sulfide, and zomepirac displaced [3H]PGD2 binding at the mouse CRTH2 receptor (mCRTH2) with comparable affinity (Ki = 1.5 +/- 0.1, 2.5 +/- 0.4, and 3.3 +/- 0.3 microM, respectively). The indomethacin metabolite 5'-O-desmethyl indomethacin (5'-DMI) possessed binding affinity similar to indomethacin; however, elimination of the 2-methyl substituent on the indole ring resulted in a 10-fold decrease in binding affinity. No binding was detected for indole acetic acid and indole derivatives such as tryptophan, serotonin, and 5-hydroxy indole acetic acid, demonstrating the importance of the N-acyl moiety of indomethacin. Neutral derivatives of indomethacin also failed to bind to mCRTH2, suggesting that the negatively charged carboxylate moiety participates in a key ligand-receptor interaction. Despite similar binding affinities, NSAID-type mCRTH2 ligands exhibited variable potencies as mCRTH2 agonists. Sulindac sulfide and 5'-DMI inhibited intracellular cyclic AMP ([cAMP]i) generation and stimulated cell migration comparable with indomethacin. In contrast, zomepirac did not inhibit [cAMP]i generation or stimulate cell migration but weakly antagonized the effects of indomethacin on [cAMP]i. Together, these results reveal structural features of arylacetic acid NSAIDs that may be exploited for the development of selective CRTH2 ligands.
authors.affiliation: Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-2372, USA.
authors.forename: Aaron N
authors.initials: AN
authors.lastname: Hata
authors.forename: Terry P
authors.initials: TP
authors.lastname: Lybrand
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Marnett
authors.forename: Richard M
authors.initials: RM
authors.lastname: Breyer
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry* / Q000493:pharmacokinetics* / Q000494:pharmacology; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D004441:Ecdysterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D007213:Indomethacin / Q000493:pharmacokinetics / Q000494:pharmacology; D007668:Kidney; D051379:Mice; D015230:Prostaglandin D2 / Q000378:metabolism*; D011869:Radioligand Assay; D011971:Receptors, Immunologic / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D011982:Receptors, Prostaglandin / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D014162:Transfection; D014316:Tritium
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D011971:Receptors, Immunologic; D011982:Receptors, Prostaglandin; D011994:Recombinant Proteins; D014316:Tritium; D004441:Ecdysterone; C008999:ponasterone A; D000242:Cyclic AMP; D015230:Prostaglandin D2; D007213:Indomethacin; C036293:prostaglandin D2 receptor