title: Requirement of the enzymatic and signaling activities of plasmin for phorbol-ester-induced scattering of colon cancer cells.
abstract: Colon cancer progression is associated with the activation of protein kinase C (PKC), the downregulation of functional E-cadherin and an increased expression of the serine protease urokinase (u-PA) and its receptor (u-PAR). HT29-M6 intestinal epithelial cells represent an in vitro model to study colon cancer progression. These cells are induced to scatter and to invade by phorbol esters. Using proteolytic and cell signaling inhibitors, we show that HT29-M6 cells require plasminogen for the acquisition of the scattering response to PMA. Our results indicate that, prior to inducing a state of competency for plasminogen-dependent scattering, PMA triggers an ordered succession of events where upregulation of the activity of u-PA precedes proteolysis of u-PAR and active degradation of the extracellular matrix (ECM). These events poise HT29-M6 cells to a scatter-competent state that allows the subsequent localized proteolytic activation of plasminogen to plasmin, required for the execution of scattering. Finally, we show that, in addition to its enzymatic activity directed at the degradation of ECM, plasmin generates an intracellular signal resulting in the phosphorylation of ERK 1/2. For a full motogenic activity, plasmin requires this signal since the use of a MEK inhibitor (PD98059) specifically blocks the plasmin-dependent phase of cell scattering. Our observations suggest that plasmin exerts a dual role in PMA-induced scattering of HT29-M6 cells, one directed extracellularly to promote proteolysis of the ECM and one directed to generate intracellular signaling.
authors.affiliation: Unitat Recerca Biomèdica, Institut de Recerca Hospital Vall d' Hebron, Barcelona, Spain.
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Díaz
authors.forename: Mariano
authors.initials: M
authors.lastname: Hurtado
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Kort
authors.forename: Massimo
authors.initials: M
authors.lastname: Resnati
authors.forename: Francesco
authors.initials: F
authors.lastname: Blasi
authors.forename: Timothy
authors.initials: T
authors.lastname: Thomson
authors.forename: Rosanna
authors.initials: R
authors.lastname: Paciucci
mesh_terms: D015119:Aminocaproic Acid / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005341:Fibrinolysin / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D019073:HT29 Cells; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010958:Plasminogen / Q000172:deficiency / Q000378:metabolism / Q000494:pharmacology; D017395:Plasminogen Activator Inhibitor 1 / Q000494:pharmacology; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D005419:Flavonoids; C066855:HGF protein, human; D019012:Integrin beta1; C524898:PLAUR protein, human; D017395:Plasminogen Activator Inhibitor 1; D011720:Pyrazoles; D011743:Pyrimidines; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D017228:Hepatocyte Growth Factor; D010958:Plasminogen; D037342:Pertussis Toxin; D051571:Protein Kinase C-alpha; D048049:Extracellular Signal-Regulated MAP Kinases; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D015119:Aminocaproic Acid