Thrombin enhances adhesion in pancreatic cancer in vitro through the activation of the thrombin receptor PAR 1

Background: Thrombin, the central enzyme of the coagulation cascade, induces proliferation in different solid tumours. The effect is mainly mediated through the functional thrombin receptor PAR 1, a member of the G-protein coupled receptor family. The aim of this study was to assess the role of thrombin on adhesion of pancreatic cancer to extracellular matrix proteins and endothelial cells in vitro. Materials and Methods: The human pancreatic adenocarcinoma cell line MIA PaCa-2 was treated with thrombin and the thrombin-receptor-activing peptide (TRAP), respectively. As a control the cells were pre-incubated with the thrombin-receptor-inhibiting peptide (T1). The cells were incubated on microtiter plates, which were pre-coated with extracellular matrix proteins (fibronectin, laminin, collagen IV) or human umbilical vein endothelial cells (HUVECs), for 30 and 60 min, respectively. The number of adherent cells were measured using the MTT method. ANOVA was used for statistical analysis. Results: Thrombin enhanced the adhesion of MIA PaCa-2 cells to extra-cellular matrix proteins and endothelial cells significantly (P≤0.001). The effects of thrombin could be mimicked by TRAP. Pre-incubation with T1 inhibited the effect. Conclusion: Thrombin enhances adhesion of pancreatic adenocarcinoma to extracellular matrix proteins and endothelial cellsin vitro. The effect is mediated through the thrombin receptor PAR 1. The results emphasize the role of thrombin and PAR 1 in pancreatic tumour biology.