title: Identification of integrin collagen receptors on human melanoma cells.
abstract: Integrin receptors may mediate the adhesion of cells to a number of extracellular matrix components. We found that the attachment of human melanoma cells to collagen types I and IV was blocked by antibodies to the integrin beta 1 subunit but not by peptides containing the Arg-Gly-Asp sequence. Ligand affinity chromatography was used to search for integrin-related receptors which mediate adhesion to native collagens. Detergent extracts of surface 125I-iodinated melanoma cells were chromatographed on type I or IV collagen-Sepharose columns. Bound material was eluted and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. EDTA, but not Arg-Gly-Asp peptides, eluted a mixture of two integrin-related heterodimeric complexes. Each complex contained the integrin beta 1 chain with Mr of 110,000 and a distinct alpha chain with Mr of either 200,000 or 150,000. Immunoprecipitation with specific monoclonal antibodies identified the complexes as very late activation antigen (VLA)-1 (alpha 1 beta 1) and VLA-2 (alpha 2 beta 1), respectively. The binding of these receptors to collagen appeared to be specific because they failed to be retained on fibronectin- or laminin-Sepharose columns. Immunofluorescent staining of cells on collagen substrates with antibodies to VLA-1 and VLA-2 localized these complexes in vinculin-positive adhesion plaques. In contrast, the receptor complexes were not detected in adhesion plaques of cells attached to fibronectin- or laminin-coated substrates. These results indicate that melanoma cells express at least two different integrin-related collagen-binding receptor complexes that appear to mediate cell adhesion to collagen.
authors.affiliation: Department of Anatomy, School of Medicine, University of California, San Francisco 94143.
authors.forename: R H
authors.initials: RH
authors.lastname: Kramer
authors.forename: N
authors.initials: N
authors.lastname: Marks
mesh_terms: D000906:Antibodies; D000911:Antibodies, Monoclonal; D002448:Cell Adhesion; D002846:Chromatography, Affinity; D003094:Collagen / Q000378:metabolism; D004492:Edetic Acid; D004591:Electrophoresis, Polyacrylamide Gel; D005353:Fibronectins / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007163:Immunosorbent Techniques; D016023:Integrins; D046911:Macromolecular Substances; D008545:Melanoma / Q000032:analysis* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000502:physiology; D008970:Molecular Weight; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000502:physiology; D038981:Receptors, Collagen; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000276:immunology; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D005353:Fibronectins; D016023:Integrins; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D038981:Receptors, Collagen; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic; D003094:Collagen; D004492:Edetic Acid