Abstract
Known agonists of the orphan receptor GPR35 are kynurenic acid, zaprinast, 5-nitro-2-(3-phenylproplyamino) benzoic acid, and lysophosphatidic acids. Their relatively low affinities for GPR35 and prominent off-target effects at other pathways, however, diminish their utility for understanding GPR35 signaling and for identifying potential therapeutic uses of GPR35. In a screen of the Prestwick Library of drugs and drug-like compounds, we have found that pamoic acid is a potent GPR35 agonist. Pamoic acid is considered by the Food and Drug Administration as an inactive compound that enables long-acting formulations of numerous drugs, such as the antihelminthics oxantel pamoate and pyrantel pamoate; the psychoactive compounds hydroxyzine pamoate (Vistaril) and imipramine pamoate (Tofranil-PM); and the peptide hormones triptorelin pamoate (Trelstar) and octreotide pamoate (OncoLar). We have found that pamoic acid induces a Gi/o-linked, GPR35-mediated increase in the phosphorylation of extracellular signal-regulated kinase 1/2, recruitment of β-arrestin2 to GPR35, and internalization of GPR35. In mice, it attenuates visceral pain perception, indicating an antinociceptive effect, possibly through GPR35 receptors. We have also identified in collaboration with the Sanford-Burnham Institute Molecular Libraries Probe Production Center new classes of GPR35 antagonist compounds, including the nanomolar potency antagonist methyl-5-[(tert-butylcarbamothioylhydrazinylidene)methyl]-1-(2,4-difluorophenyl)pyrazole-4-carboxylate (CID2745687). Pamoic acid and potent antagonists such as CID2745687 present novel opportunities for expanding the chemical space of GPR35, elucidating GPR35 pharmacology, and stimulating GPR35-associated drug development. Our results indicate that the unexpected biological functions of pamoic acid may yield potential new uses for a common drug constituent.
Footnotes
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The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.This research was supported by the National Institutes of Health National Institute on Drug Abuse [Grants DA023204, DA05274, DA029432, DA022950, and DA013429]. The HCS screening portion of this work was supported by the National Institutes of Health National Human Genome Research Institute Roadmap Initiative [Grant U54-HG003916] and performed at Sanford-Burnham's Conrad Prebys Center for Chemical Genomics (CPCCG), part of the Molecular Libraries Probe Production Centers Network (MLPCN) supported by the National Institutes of Health National Institute of Mental Health [Grant X01-MH085708].
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.110.066746.
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ABBREVIATIONS:
- GPCR
- G-protein-coupled receptor
- NPPB
- 5-nitro-2-(3-phenylpropylamino) benzoic acid
- HEK
- human embryonic kidney
- ERK1/2
- extracellular signal-regulated kinase
- DMEM
- Dulbecco's modified Eagle's medium
- HBSS
- Hanks' balanced salt solution
- WIN55212-2
- (R)-(+)-[2,3-dihydro-5-methyl-3-[(4-morpholinylmethyl]-pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl](1-naphthalenyl)methanone
- CP55940
- (−)-3-[2-hydroxyl-4-(1,1-dimethylheptyl)phenyl]-4-[3-hydroxyl propyl] cyclohexan-1-ol
- O-1602
- 5-methyl-4-[(1R,6R)-3-methyl-6-(1-methylenyl)-2-cyclohexen-1-yl]-1,3-benzenediol
- JWH015
- (2-methyl-1-propyl-1H-indol-3-yl)-1-naphthalenylmethanone
- AM251
- 1-(2,4-dicholorophenyl)-5-(4-iodophenyl)-4-morphoniyl-1H-pyrazole-3-carboxamide
- SR144528
- 5-(4-chloro-3-methylphenyl)-1-[(4-methylphenyl)methyl]-N-[(1S,2S,4R)-1,3,3-trimethylbicyclo[2.2.1]hept-2-yl]-1H-pyrazole-3-carboxamide
- HU-210
- (−)-11-hydroxyl-Δ8-tetrahydrocannabinol-dimethylheptyl
- CID2745687
- methyl 5-[(tert-butylcarbamothioylhydrazinylidene)methyl]-1-(2,4-difluorophenyl)pyrazole-4-carboxylate
- SR141716A
- N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide
- HA
- hemagglutinin
- GFP
- green fluorescent protein
- PCR
- polymerase chain reaction
- PBS
- phosphate-buffered saline
- PTX
- pertussis-toxin
- βarr2
- β-arrestin2
- UGPR35β
- U2OS cells permanently expressing HA-GPR35a and βarr2-GFP
- DHNA
- 1,4-dihydroxy-2-naphthoic acid
- U0126
- 1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene
- CID2745684
- methyl 1-(2,4-difluorophenyl)-5-[(methylcarbamothioylhydrazinylidene)methyl]pyrazole-4-carboxylate
- FDA
- U.S. Food and Drug Administration.
- Received June 1, 2010.
- Accepted July 22, 2010.
- Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics
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Targeting of the Orphan Receptor GPR35 by Pamoic Acid: A Potent Activator of Extracellular Signal-Regulated Kinase and β-Arrestin2 with Antinociceptive Activity
