title: The effect of thrombospondin on invasion of fibrin gels by human A549 lung carcinoma.
abstract: Thrombospondin (TSP) was evaluated for its effect on the capacity of human A549 lung adenocarcinoma cells to invade and degrade fibrin gels. Cells suspended in DMEM containing 0.01 units/mL plasminogen were added to a 2.5 mm diameter well in a 2 mm thick fibrin gel. Various concentrations of TSP were added either to the cells or to the gel. After 18 hours, the number of spread and gel-adherent cells were counted and the diameter of the well was measured to determine the extent of tumor-induced fibrinolysis. In the absence of TSP, the tumor cells were non-adherent but catalyzed the rapid degradation of the fibrin gel, causing the application well to increase in diameter several-fold. In contrast, addition of either TSP to the gel or to the cell suspension inhibited fibrinolysis in a dose-dependent manner and promoted attachment and spreading of cells in the fibrin matrix. In contrast, fibronectin had no effect. The effect of TSP on both tumor cell-associated fibrinolysis and cell adhesion was inhibited with an anti-TSP monoclonal antibody. The cell adhesive peptides CSVTCG, derived from the type 1 repeats of TSP, and GRGDS also had no effect on tumor cell-associated fibrinolysis. TSP inhibited fibrinolysis by inhibiting tumor cell-secreted urokinase activity, but had no effect on total urokinase secreted-antigen. In contrast, cell-associated urokinase activity was protected from inhibition by TSP. These results suggest that TSP may promote tumor cell metastasis not only by promoting cell-attachment but also by protecting tumor cell-fibrin emboli from degradation by tumor secreted- and host fibrinolytic enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, Medical College of Pennsylvania, Philadelphia 19129.
authors.forename: T
authors.initials: T
authors.lastname: Hosokawa
authors.forename: A
authors.initials: A
authors.lastname: Muraishi
authors.forename: V L
authors.initials: VL
authors.lastname: Rothman
authors.forename: M
authors.initials: M
authors.lastname: Papale
authors.forename: G P
authors.initials: GP
authors.lastname: Tuszynski
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology*; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000276:immunology / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects; D005341:Fibrinolysin / Q000032:analysis; D005342:Fibrinolysis / Q000187:drug effects*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000473:pathology*; D008562:Membrane Glycoproteins / Q000276:immunology / Q000494:pharmacology*; D009361:Neoplasm Invasiveness / Q000503:physiopathology / Q000517:prevention & control*; D019699:Thrombospondins; D014407:Tumor Cells, Cultured; D014568:Urokinase-Type Plasminogen Activator / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D008562:Membrane Glycoproteins; D019699:Thrombospondins; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator