title: Expression of c-Met proto-oncogene in metastatic macrophage x melanoma fusion hybrids: implication of its possible role in MSH-induced motility.
abstract: It was shown previously that a majority of hybrids produced by in vitro fusion of normal macrophages with Cloudman S91 melanoma cells displayed macrophage-specific glycosylation, especially increased GnT-V activity, beta1,6 branch formation in glycoproteins, accompanied by enhanced metastatic potential in vivo and motility in vitro. These hybrids also express upregulated melanocortin-1 receptor (MC1-R) activity and exhibit increased motility after melanocyte-stimulating hormone (MSH) treatment. In this report, we show that MSH-mediated stimulation of motility is mediated through enhanced expression of c-Met proto-oncogene. In metastatic hybrids c-Met expression is induced by MSH, and addition of c-Met neutralizing antibody to cells inhibits MSH-induced motility but not the basal motility of the cells. Furthermore, abrogation of the chemoattractant gradient concentration by addition of hepatocyte growth factor (HGF) recombinant protein, a cognate ligand of c-Met receptor, reduces the MSH-induced effect on motility. A similar result was also obtained by the addition of blocking anti-alphaHGF antibody in the chemoattractant chamber. Again, the metastatic hybrids, but not the nonmetastatic hybrids or parental melanoma cells, showed significant motile response to rHGF chemoattractant, and that motility is further induced when cells were stimulated with MSH/isobutylmethyl xanthine (IBMX). Synergistic stimulation on motility was also observed with those hybrids treated with MSH/IBMX and when rHGF and fibronectin (FN), in combination, were used as chemoattractants. These indicate that MSH/IBMX-induced motility might involve c-Met pathways as well as extracellular matrix (ECM)/integrin pathways in a cooperative fashion. Ets-1, a transcription factor involved in the expression of c-Met, is also found to be induced in metastatic hybrids after exposure to MSH/IBMX. Implication of the result is discussed in light of the role of c-Met and its interacting proteins in the development of metastatic phenotypes and its therapeutic intervention.
authors.affiliation: Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA. ashok.chakraborty@yale.edu
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Chakraborty
authors.forename: Natalia
authors.initials: N
authors.lastname: Kolesnikova
authors.forename: Josane de Freitas
authors.initials: Jde F
authors.lastname: Sousa
authors.forename: Enilza Maria
authors.initials: EM
authors.lastname: Espreafico
authors.forename: Kamila Chagas
authors.initials: KC
authors.lastname: Peronni
authors.forename: John
authors.initials: J
authors.lastname: Pawelek
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects*; D005353:Fibronectins / Q000494:pharmacology; D005434:Flow Cytometry; D017228:Hepatocyte Growth Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006822:Hybrid Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology*; D008545:Melanoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D009362:Neoplasm Metastasis / Q000235:genetics; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000235:genetics; D050783:Proto-Oncogene Proteins c-ets; D019859:Proto-Oncogene Proteins c-met / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics
chemical_list: C494042:Ets1 protein, mouse; D005353:Fibronectins; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014157:Transcription Factors; D017228:Hepatocyte Growth Factor; D009074:Melanocyte-Stimulating Hormones; D019859:Proto-Oncogene Proteins c-met