Tumour cell thrombospondin-1 regulates tumour cell adhesion and invasion through the urokinase plasminogen activator receptor.
We have previously shown that platelet-produced thrombospondin-1 up-regulates the urokinase plasminogen activator and its receptor and promotes tumour cell invasion. Although tumour cells produce thrombospondin-1 in vivo, they produce only minimal amounts of thrombospondin-1 in vitro. To determine the effect of tumour cell-produced thrombospondin-1 in the regulation of the plasminogen/plasmin system and tumour cell invasion, we studied THBS-1-transfected MDA-MB-435 breast cancer cells that overexpress thrombospondin-1. The role of urokinase plasminogen receptor in thrombospondin-1-mediated adhesion and invasion was studied by antisense inhibition, enzymatic cleavage and antibody neutralization. Tumour cell adhesion to collagen and laminin was evaluated. Tumour cell invasion was studied in a modified Boyden chamber collagen invasion assay. Tumour cell thrombospondin-1 induced a 2-7 fold increase in urokinase plasminogen activator receptor and cell-associated urokinase plasminogen activator expression and a 50-65% increase in cell-associated urokinase plasminogen activator and plasmin activities. Furthermore, tumour cell thrombospondin-1 promoted tumour cell invasion and decreased tumour cell adhesion through up-regulation of urokinase plasminogen activator receptor-controlled urokinase plasminogen activator and plasmin activities. We conclude that tumour cell-produced thrombospondin-1 may play a critical role in the regulation of tumour cell adhesion and tumour cell invasion.
Department of Surgery, MCP Hahnemann University, Philadelphia, PA 19102, USA.
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Albo
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Rothman
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Roberts
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Tuszynski
D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002448:Cell Adhesion; D004797:Enzyme-Linked Immunosorbent Assay; D005341:Fibrinolysin / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009361:Neoplasm Invasiveness; D010958:Plasminogen / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator; D019700:Thrombospondin 1 / Q000378:metabolism*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D019700:Thrombospondin 1; D016212:Transforming Growth Factor beta; D010958:Plasminogen; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator