Transforming growth factor-beta enhances adhesion of melanoma cells to the endothelium in vitro.
Melanoma invasion requires migration through the vascular barrier. An early event in this process is the adhesion of metastatic cells to the endothelium. To elucidate the role of TGF-beta in the regulation of this process, human melanoma SK-MEL24 cells were labelled with [5'-(3)H]-thymidine and co-cultured with bovine pulmonary artery endothelial-cell monolayers. Radioactivity was assumed to be proportional to the number of SK-MEL24 cells bound to the endothelium. A low number of melanoma cells adhered to endothelial cells in a time-related manner. Pretreatment for 24 hr with 0.001 to 10 ng/ml TGF-beta1 or TGF-beta2 of both cell types enhanced melanoma-endothelium adhesion in a dose-dependent manner. Both melanoma and endothelial cells expressed RI- and RII-type TGF-beta receptors. The effect of TGF-beta was abolished by co-incubation with the proteoglycan decorin. Conditioned media from melanoma-endothelium co-cultures contained latent TGF-beta and failed to affect cell-cell adhesion. However, activation of TGF-beta by heating the medium or reducing the pH, increased melanoma-endothelium adhesion to an extent similar to that of the TGF-beta administered to the cultures. Zimography demonstrated that both cell types expressed urokinase-type plasminogen activator (uPA). Addition of plasminogen to the co-cultures, which was likely to be activated to plasmin by uPA, resulted in activation of TGF-beta and parallel stimulation of melanoma-endothelium adhesion. In conclusion, TGF-beta may enhance adhesion of melanoma cells to the endothelium, playing a relevant autocrine/paracrine role in the progression of invasive melanoma.
Teti
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Department of Experimental Medicine, University of L'Aquila, Italy.
De Giorgi
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Spinella
M T
MT
Migliaccio
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S
Canipari
R
R
Onetti Muda
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A
Faraggiana
T
T
D030201:Activin Receptors, Type I; D000818:Animals; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects*; D002478:Cells, Cultured; D018920:Coculture Techniques; D058575:Decorin; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D016326:Extracellular Matrix Proteins; D005341:Fibrinolysin / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008545:Melanoma / Q000473:pathology / Q000503:physiopathology*; D010958:Plasminogen / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis; D011509:Proteoglycans / Q000494:pharmacology; D011651:Pulmonary Artery; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology; D012878:Skin Neoplasms / Q000473:pathology / Q000503:physiopathology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis
C546878:DCN protein, human; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D010958:Plasminogen; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator