title: Signaling via G proteins mediates tumorigenic effects of GPR87.
abstract: G protein-coupled receptors (GPCRs) constitute a large protein family of seven transmembrane (7TM) spanning proteins that regulate multiple physiological functions. GPR87 is overexpressed in several cancers and plays a role in tumor cell survival. Here, the basal activity of GPR87 was investigated in transiently transfected HEK293 cells, revealing ligand-independent coupling to Gαi, Gαqand Gα12/13. Furthermore, GPR87 showed a ligand-independent G protein-dependent activation of the downstream transcription factors CREB, NFκB, NFAT and SRE. In tetracycline-induced Flp-In T-Rex-293 cells, GPR87 induced cell clustering presumably through Gα12/13coupling. In a foci formation assay using retrovirally transduced NIH3T3 cells, GPR87 showed a strong in vitro transforming potential, which correlated to the in vivo tumor induction in nude mice. Importantly, we demonstrate that the transforming potential of GPR87 was correlated to the receptor signaling, as the signaling-impaired mutant R139A (Arg in the conserved "DRY"-motif at the bottom of transmembrane helix 3 of GPR87 substituted to Ala) showed a lower in vitro cell transformation potential. Furthermore, R139A lost the ability to induce cell clustering. In summary, we show that GPR87 is active through several signaling pathways and that the signaling activity is linked to the receptor-induced cell transformation and clustering. The robust surface expression of GPR87 and general high druggability of GPCRs make GPR87 an attractive future anticancer target for drugs that - through inhibition of the receptor signaling - will inhibit its transforming properties.
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Kristine
authors.initials: K
authors.lastname: Niss Arfelt
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Suzan
authors.initials: S
authors.lastname: Fares
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Alexander H
authors.initials: AH
authors.lastname: Sparre-Ulrich
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Gertrud M
authors.initials: GM
authors.lastname: Hjortø
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Lærke S
authors.initials: LS
authors.lastname: Gasbjerg
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Ann-Sofie
authors.initials: AS
authors.lastname: Mølleskov-Jensen
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Tau
authors.initials: T
authors.lastname: Benned-Jensen
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address: Rosenkilde@sund.ku.dk.
authors.forename: Mette M
authors.initials: MM
authors.lastname: Rosenkilde
mesh_terms: D000818:Animals; D019556:COS Cells; D063646:Carcinogenesis / Q000378:metabolism* / Q000473:pathology*; D002462:Cell Membrane / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000473:pathology; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008024:Ligands; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism; D041681:NIH 3T3 Cells; D049368:Receptors, Lysophosphatidic Acid / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism
chemical_list: C526276:GPR87 protein, human; D008024:Ligands; D008246:Lysophospholipids; D050505:Mutant Proteins; D049368:Receptors, Lysophosphatidic Acid; D014157:Transcription Factors; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D054460:rho-Associated Kinases; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; C032881:lysophosphatidic acid
keywords: Anticancer drugs; Cell clustering; Cell signaling,; Cell transformation; GPR87