title: Cytokine-regulated urokinase-type-plasminogen-activator (uPA) production by human breast fibroblasts in vitro.
abstract: It has been shown that, in breast stroma, urokinase-type plasminogen activator (uPA) mRNA is predominantly expressed by myofibroblasts located at the invasive areas of the tumor. To examine which factors present in a tumor environment are candidates responsible for the induction of these uPA-producing myofibroblasts, we studied in vitro the capacity of a paired panel of normal and tumor-derived human breast fibroblasts to produce uPA protein and the myofibroblast marker alpha-smooth-muscle-actin (alpha-SMA) in response to various cytokines implicated in the process of tissue-remodeling during malignant transformation. We found that fibroblasts produced increased amounts of uPA protein after exposure to a-FGF, b-FGF, EGF, PDGF-BB, and IFN-gamma, were unaffected in this respect by IL-6, M-CSF, GM-CSF and Oncostatin M, and produced decreased amounts of uPA protein after exposure to IL-1alpha, TNF-alpha, IGF-I, and IGF-II. None of these cytokines were able to induce a striking increase in the fraction of alpha-SMA-positive fibroblasts. On the other hand, 25 pM TGFbeta1 increased the fraction of alpha-SMA-positive fibroblasts 5-fold in both normal and tumor-tissue-derived fibroblasts. Nonetheless, the normal-derived fibroblasts were unaffected in their uPA-producing capacity by TGFbeta1, and the tumor-derived fibroblasts produced decreased amounts of uPA protein after exposure to this cytokine, implying that at least in vitro the myofibroblast phenotype is not a prerequisite for the production of uPA by human breast fibroblasts. In addition, we established that the basal-uPA-production of both normal and tumor-derived fibroblasts was increased by autocrinely produced b-FGF-like activity, and that the basal-uPA-production of at least the normal-derived fibroblasts was decreased by autocrinely produced IGF-like activity. Altogether, our data suggest an active role for fibroblasts in the process of uPA-directed breast tumor proteolysis.
authors.affiliation: Department of Medical Oncology, Rotterdam Cancer Institute (Daniel den Hoed Kliniek)/Academic Hospital Rotterdam, The Netherlands. Sieuwerts@bidh.azr.nl
authors.forename: A M
authors.initials: AM
authors.lastname: Sieuwerts
authors.forename: J G
authors.initials: JG
authors.lastname: Klijn
authors.forename: S C
authors.initials: SC
authors.lastname: Henzen-Logmans
authors.forename: J A
authors.initials: JA
authors.lastname: Foekens
mesh_terms: D001940:Breast / Q000166:cytology / Q000201:enzymology* / Q000276:immunology; D001943:Breast Neoplasms / Q000201:enzymology* / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000276:immunology / Q000502:physiology; D005347:Fibroblasts / Q000201:enzymology* / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000502:physiology; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis* / Q000276:immunology
chemical_list: D016207:Cytokines; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D014568:Urokinase-Type Plasminogen Activator