title: The role of beta 1 integrins in adhesion of two breast carcinoma cell lines to a model endothelium.
abstract: Interactions between tumour cells and the endothelium are vital to the formation of haematogenous metastases. Binding to model endothelium of one oestrogen receptor positive breast carcinoma cell line (MCF-7) and one receptor negative line (HS578T) was examined in vitro together with endothelial retraction induced by these tumour cells. Adhesion was inhibited by monoclonal antibodies specific for the VLA integrins and by peptides containing the RGD motif which is commonly recognised as a ligand by the VLA adhesion molecules. However, binding of the two tumour cell lines was inhibited by monoclonal antibodies specific for different VLA molecules; anti-alpha 6 beta 1 inhibited MCF-7 adhesion but anti-alpha 5 beta 1 inhibited Hs578T. These results were consistent with flow cytometric quantification of the expression of these VLA integrins on the surfaces of the two tumour cell lines. Enzyme-linked immunosorbent assays (ELISA) demonstrated that laminin was present on the endothelial cell surface but collagen IV was absent. ELISA failed to detect increased exposure of the subendothelial matrix during the first hour after addition of either cancer cell type. This was supported by assays which demonstrated maintenance of the endothelial permeability barrier during this period. Slight endothelial retraction was detected within 2 hours of the addition of tumour cells. It is concluded that binding between tumour cells and confluent endothelium is inhibited by the blockade of adhesion molecules which are normally associated with interactions between the cell and the subendothelial matrix. Tumour cell to matrix interactions rather than direct tumour to endothelial cell adhesion may be the limiting step in tumour cell binding to the endothelium.
authors.affiliation: Department of Surgery, Medical School, Newcastle upon Tyne, UK.
authors.forename: R D
authors.initials: RD
authors.lastname: Bliss
authors.forename: J A
authors.initials: JA
authors.lastname: Kirby
authors.forename: D A
authors.initials: DA
authors.lastname: Browell
authors.forename: T W
authors.initials: TW
authors.lastname: Lennard
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000918:Antibody Specificity; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D002448:Cell Adhesion / Q000502:physiology; D003094:Collagen / Q000032:analysis; D004492:Edetic Acid / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D019012:Integrin beta1; D016023:Integrins / Q000378:metabolism / Q000502:physiology*; D007797:Laminin / Q000032:analysis; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013696:Temperature; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D019012:Integrin beta1; D016023:Integrins; D007797:Laminin; D009842:Oligopeptides; D011960:Receptors, Estrogen; C047981:arginyl-glycyl-aspartic acid; D003094:Collagen; D004492:Edetic Acid