title: EGF-R signaling through Fyn kinase disrupts the function of integrin alpha6beta4 at hemidesmosomes: role in epithelial cell migration and carcinoma invasion.
abstract: We have examined the mechanism and functional significance of hemidesmosome disassembly during normal epithelial cell migration and squamous carcinoma invasion. Our findings indicate that a fraction of EGF receptor (EGF-R) combines with the hemidesmosomal integrin alpha6beta4 in both normal and neoplastic keratinocytes. Activation of the EGF-R causes tyrosine phosphorylation of the beta4 cytoplasmic domain and disruption of hemidesmosomes. The Src family kinase inhibitors PP1 and PP2 prevent tyrosine phosphorylation of beta4 and disassembly of hemidesmosomes without interfering with the activation of EGF-R. Coimmunoprecipitation experiments indicate that Fyn and, to a lesser extent, Yes combine with alpha6beta4. By contrast, Src and Lck do not associate with alpha6beta4 to a significant extent. A dominant negative form of Fyn, but not Src, prevents tyrosine phosphorylation of beta4 and disassembly of hemidesmosomes. These observations suggest that the EGF-R causes disassembly of hemidesmosomes by activating Fyn, which in turn phosphorylates the beta4 cytoplasmic domain. Neoplastic cells expressing dominant negative Fyn display increased hemidesmosomes and migrate poorly in vitro in response to EGF. Furthermore, dominant negative Fyn decreases the ability of squamous carcinoma cells to invade through Matrigel in vitro and to form lung metastases following intravenous injection in nude mice. These results suggest that disruption of hemidesmosomes mediated by Fyn is a prerequisite for normal keratinocyte migration and squamous carcinoma invasion.
authors.affiliation: Cellular Biochemistry and Biophysics Program, Department of Surgery, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mariotti
authors.forename: P A
authors.initials: PA
authors.lastname: Kedeshian
authors.forename: M
authors.initials: M
authors.lastname: Dans
authors.forename: A M
authors.initials: AM
authors.lastname: Curatola
authors.forename: L
authors.initials: L
authors.lastname: Gagnoux-Palacios
authors.forename: F G
authors.initials: FG
authors.lastname: Giancotti
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000502:physiology; D066246:ErbB Receptors / Q000378:metabolism*; D022002:Hemidesmosomes / Q000378:metabolism / Q000502:physiology; D006801:Humans; D039161:Integrin alpha6beta4; D016023:Integrins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009374:Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D051381:Rats; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D039161:Integrin alpha6beta4; D016023:Integrins; D011518:Proto-Oncogene Proteins; D066246:ErbB Receptors; C494957:FYN protein, human; C494960:Fyn protein, mouse; C494961:Fyn protein, rat; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases