title: SMAD3 is essential for transforming growth factor-β1-induced urokinase type plasminogen activator expression and migration in transformed keratinocytes.
abstract: Transforming growth factor-β1 (TGF-β1) stimulates the extracellular matrix degrading proteases expression and cell migration in order to enhance cancer cells malignancy. In the present study, we analysed the role of TGF-β1-induced Smad3 activation in the urokinase type plasminogen activator (uPA) production, as well as in cell migration and E-cadherin downregulation in transformed PDV keratinocyte cell line. TGF-β1 signalling was interfered by the chemical inhibitor of the TGF-β1-receptor 1 (ALK5), SB505124, and the specific Smad3 inhibitor, SiS3. Our results showed that TGF-β1 stimulates uPA expression directly through ALK5 activation. The inhibition of Smad3 strongly reduced the capacity of TGF-β1 to stimulate uPA expression, in parallel decreasing the uPA inhibitor plasminogen activator inhibitor type 1 (PAI-1) expression. In addition, the transient expression of dominant negative Smad3 mutant inhibited the TGF-β1-induced uPA promoter transactivation. Moreover, Smad3-/- mouse embryonic fibroblasts were refractory to the induction of uPA by TGF-β1. The inhibition of both ALK5 and Smad3 dramatically blocked the TGF-β1-stimulated E-cadherin downregulation, F-actin reorganisation and migration of PDV cells. Taken together, our results suggest that the TGF-β1-induced activation of Smad3 is the critical step for the uPA upregulation and E-cadherin downregulation, which are the key events preceding the induction of cell migration by TGF-β1 in transformed cells.
authors.affiliation: Laboratory for Experimental Hematology, Institute for Medical Research, University of Belgrade, Dr. Subotica 4, PO Box 102, 11129 Belgrade, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Kocic
authors.forename: Diana
authors.initials: D
authors.lastname: Bugarski
authors.forename: Juan F
authors.initials: JF
authors.lastname: Santibanez
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002465:Cell Movement; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D015603:Keratinocytes / Q000166:cytology*; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D051900:Smad3 Protein / Q000235:genetics* / Q000502:physiology*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis*
chemical_list: D015820:Cadherins; D018125:Receptors, Transforming Growth Factor beta; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human; C000625842:Tgfbr1 protein, mouse; D014568:Urokinase-Type Plasminogen Activator