title: Increased extracellular pressure enhances cancer cell integrin-binding affinity through phosphorylation of beta1-integrin at threonine 788/789.
abstract: Increased extracellular pressure stimulates beta1-integrin-dependent cancer cell adhesion. We asked whether pressure-induced adhesion is mediated by changes in beta1-integrin binding affinity or avidity and whether these changes are phosphorylation dependent. We evaluated integrin affinity and clustering in human SW620 colon cancer cells by measuring differences in binding between soluble Arg-Gly-Asp (RGD)-Fc ligands and RGD-Fc-F(ab')2 multimeric complexes under ambient and 15-mmHg increased pressures. Phosphorylation of beta1-integrin S785 and T788/9 residues in SW620 and primary malignant colonocytes was assessed in parallel. We further used GD25-beta1-integrin-null murine fibroblasts stably transfected with either wild-type beta1A-integrin, S785A, TT788/9AA, or T788D mutants to investigate the role of beta1-integrin site-specific phosphorylation. SW620 binding of RGD-Fc-F(ab')2 multimeric complexes, but not soluble RGD-Fc ligands, was sensitive to integrin clustering. RGD-Fc ligand binding was significantly increased under elevated pressure, suggesting that pressure modulates beta1-integrin affinity. Pressure stimulated both beta1-integrin S785 and T788/9 phosphorylation. GD25-beta1A-integrin wild-type and S785A cells displayed an increase in adhesion to fibronectin under elevated pressure, an effect absent in beta1-integrin-null and TT788/9AA cells. T788D substitution significantly elevated basal cell adhesion but displayed no further increase under pressure. These results suggest pressure-induced cell adhesion is mediated by beta1-integrin T788/9 phosphorylation-dependent changes in integrin binding affinity.
authors.affiliation: Department of Surgery, John D. Dingell VA Medical Center, 4646 John R. Street, Detroit, MI 48201-1932, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Craig
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Gayer
authors.forename: Keri L
authors.initials: KL
authors.lastname: Schaubert
authors.forename: Yanzhang
authors.initials: Y
authors.lastname: Wei
authors.forename: Jinhua
authors.initials: J
authors.lastname: Li
authors.forename: Yasmina
authors.initials: Y
authors.lastname: Laouar
authors.forename: Marc D
authors.initials: MD
authors.lastname: Basson
mesh_terms: D000185:Actinin / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003110:Colonic Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D005353:Fibronectins / Q000378:metabolism; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D006801:Humans; D019012:Integrin beta1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D040542:Mechanotransduction, Cellular; D051379:Mice; D018345:Mice, Knockout; D009362:Neoplasm Metastasis; D009842:Oligopeptides / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011312:Pressure; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013912:Threonine; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000185:Actinin; D005353:Fibronectins; D051417:Focal Adhesion Kinase 1; D019012:Integrin beta1; D009842:Oligopeptides; D019869:Phosphatidylinositol 3-Kinases; D011993:Recombinant Fusion Proteins; D013912:Threonine; D019061:src-Family Kinases; C526905:ACTN1 protein, human; C047981:arginyl-glycyl-aspartic acid; C496050:PTK2 protein, human