title: SRC family kinases mediate epidermal growth factor receptor ligand cleavage, proliferation, and invasion of head and neck cancer cells.
abstract: Head and neck squamous cell carcinomas (HNSCCs) are characterized by up-regulation of the epidermal growth factor receptor (EGFR). We previously reported that a gastrin-releasing peptide/gastrin-releasing peptide receptor (GRP/GRPR) autocrine growth pathway is activated early in HNSCC carcinogenesis. GRP can induce rapid phosphorylation of EGFR and p42/44 mitogen-activated protein kinase (MAPK) activation in part via extracellular release of transforming growth factor alpha (TGF-alpha) by matrix metalloproteinases (MMPs). It has been reported that Src family kinases are activated by G-protein-coupled receptors (GPCRs), followed by downstream EGFR and MAPK activation. To further elucidate the mechanism of activation of EGFR by GRP in HNSCC, we investigated the role of Src family kinases. Blockade of Src family kinases using an Src-specific tyrosine kinase inhibitor A-419259 decreased GRP-induced EGFR phosphorylation and MAPK activation. GRP also failed to induce MAPK activation in dominant-negative c-Src-transfected HNSCC cells. Invasion and growth assays showed that c-Src was required for GRP-induced proliferation or invasion of HNSCC cells. In addition to TGF-alpha release, GRP induced amphiregulin, but not EGF, secretion into HNSCC cell culture medium, an effect that was blocked by the MMP inhibitor marimastat. TGF-alpha and amphiregulin secretion by GRP stimulation also was inhibited by blockade of Src family kinases. These results suggest that Src family kinases contribute to GRP-mediated EGFR growth and invasion pathways by facilitating cleavage and release of TGF-alpha and amphiregulin in HNSCC.
authors.affiliation: Department of Otolaryngology, University of Pittsburgh School of Medicine and University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Sufi M
authors.initials: SM
authors.lastname: Thomas
authors.forename: Sichuan
authors.initials: S
authors.lastname: Xi
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Smithgall
authors.forename: Jill M
authors.initials: JM
authors.lastname: Siegfried
authors.forename: Joanne
authors.initials: J
authors.lastname: Kamens
authors.forename: William E
authors.initials: WE
authors.lastname: Gooding
authors.forename: Jennifer Rubin
authors.initials: JR
authors.lastname: Grandis
mesh_terms: D066258:Amphiregulin; D002294:Carcinoma, Squamous Cell / Q000201:enzymology* / Q000473:pathology*; D002455:Cell Division / Q000502:physiology; D045744:Cell Line, Tumor; D066255:EGF Family of Proteins; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D019886:Gastrin-Releasing Peptide / Q000378:metabolism / Q000494:pharmacology; D006023:Glycoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006258:Head and Neck Neoplasms / Q000201:enzymology* / Q000473:pathology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009361:Neoplasm Invasiveness; D010766:Phosphorylation; D018004:Receptors, Bombesin / Q000378:metabolism; D016211:Transforming Growth Factor alpha / Q000037:antagonists & inhibitors / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C587848:AREG protein, human; D066258:Amphiregulin; D066255:EGF Family of Proteins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D018004:Receptors, Bombesin; D016211:Transforming Growth Factor alpha; D004815:Epidermal Growth Factor; D019886:Gastrin-Releasing Peptide; D066246:ErbB Receptors; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases