The galanin receptor type 2 initiates multiple signaling pathways in small cell lung cancer cells by coupling to G(q), G(i) and G(12) proteins.
Neuropeptides like galanin produced and released by small cell lung cancer (SCLC) cells are considered principal mitogens in these tumors. We identified the galanin receptor type 2 (GALR2) as the only galanin receptor expressed in H69 and H510 cells. Photoaffinity labeling of G proteins in H69 cell membranes revealed that GALR2 activates G proteins of three subfamilies: G(q), G(i), and G(12). In H69 cells, galanin-induced Ca2+ mobilization was pertussis toxin-insensitive. While phorbol ester-induced extracellular signal-regulated kinase (ERK) activation required protein kinase C (PKC) activity, preincubation of H69 cells with the PKC-inhibitor GF109203X had no effect on galanin-dependent ERK activity. A rise of the intracellular calcium concentration was necessary and sufficient to mediate galanin-induced ERK activation. In support of G(i) coupling, stimulation of GALR2 expressed in HEK293 cells inhibited isoproterenol-induced cAMP accumulation and raised cAMP levels in COS-7 cells when coexpressed with a chimeric G alpha(S)-G alpha(i) protein In H69 cells, galanin activated the monomeric GTPase RhoA and induced stress fiber formation in Swiss 3T3 cells expressing GALR2. Thus, we provide the first direct evidence that in SCLC the mitogenic neuropeptide galanin, interacting with GALR2, simultaneously activates multiple classes of G proteins and signals through the G(q) phospholipase C/calcium sequence and a G(12)/Rho pathway. Oncogene (2000) 19, 4199 - 4209
Wittau
N
N
Institut für Pharmakologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, 14195 Berlin, Germany.
Grosse
R
R
Kalkbrenner
F
F
Gohla
A
A
Schultz
G
G
Gudermann
T
T
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D016475:3T3 Cells / Q000187:drug effects; D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D019556:COS Cells / Q000187:drug effects; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D018288:Carcinoma, Small Cell / Q000378:metabolism / Q000473:pathology*; D002448:Cell Adhesion; D000242:Cyclic AMP / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000502:physiology*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019204:GTP-Binding Proteins / Q000502:physiology*; D019004:Galanin / Q000378:metabolism / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D007545:Isoproterenol / Q000494:pharmacology; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D037342:Pertussis Toxin; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D044092:Receptor, Galanin, Type 2; D044088:Receptors, Galanin; D018013:Receptors, Neuropeptide / Q000187:drug effects / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000502:physiology
D000199:Actins; D004791:Enzyme Inhibitors; D007211:Indoles; D007295:Inositol Phosphates; D047908:Intracellular Signaling Peptides and Proteins; D008301:Maleimides; D009363:Neoplasm Proteins; D044092:Receptor, Galanin, Type 2; D044088:Receptors, Galanin; D018013:Receptors, Neuropeptide; D011993:Recombinant Fusion Proteins; D010566:Virulence Factors, Bordetella; D019004:Galanin; D000242:Cyclic AMP; D037342:Pertussis Toxin; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D007545:Isoproterenol; C070515:bisindolylmaleimide I; D015056:1-Methyl-3-isobutylxanthine