We have previously shown that thrombospondin-1 (TSP-1) and TGF-β1 upregulate the urokinase plasminogen activator (uPA) and its receptor (uPAR) and promote tumor cell invasion in breast cancer. To date, the effect of TSP- 1 and TGF-β1 on the plasminogen/plasmin system in gastrointestinal epithelial malignancies has not been investigated. In this study, we determined the effect of TSP-1 and TGF-β1 on uPA and uPAR expression and on tumor cell invasion in pancreatic cancer. ASPC1 human pancreatic adenocarcinoma cells were incubated for 48 h on cell-conditioned media (CCM) either alone (Control) or with the addition of either TSP-1 (40 μg/ml) or TGF-β1 (5 ng/ml). uPA and uPAR expression were determined by ELISA, ASPC1 cell invasion was determined in a modified Boyden chamber type I collagen invasion assay. The upper chamber was treated with CCM either alone (Control) or with the addition of anti-uPA (10 μg/ml) or anti-uPAR (10 μg/ml). The lower chamber was treated with CCM either alone (Control) or with the addition of either TSP-1 (40 μg/ml) or TGF-β1 (5 ng/ml). TSP-1 and TGF-β1 induced a twofold increase on uPAR expression but only a slight increase on total uPA. Tumor cell invasion was upregulated 3.5 to 4.5-fold by TSP-1 and TGF-β1, respectively. Anti-uPA and anti-uPAR antibodies completely blocked the TSP-1 and TGF-β1-mediated pancreatic tumor cell invasion. We conclude that TSP-1 and TGF-β1 mediate pancreatic tumor cell invasion through upregulation of the plasminogen/plasmin system.
- Pancreatic tumor cell invasion
- Thrombospondin-1 (TSP-1)
- Transforming growth factor Beta 1 (TGF- β1)
- Urokinase plasminogen activator (uPA)
- Urokinase plasminogen activator receptor (uPAR)
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