Summary Proteolysis mediated by matrix metalloproteinases (MMPs) and serine proteinases is associated with cancer invasion and metastasis. Activation of latent proMMPs, and especially the proforms of the type IV collagen degrading gelatinases A and B (proMMP-2 and proMMP-9), is thought to be a critical step in this process. We have recently found that human tumour-associated trypsin-2 is a potent activator of proMMP-9 and it also activates proMMP-2 in vitro. Trypsinogen, MMP-2, and MMP-9 are expressed in ovarian cancer. To elucidate the function of trypsin in vivo, we studied whether high concentrations of trypsinogen-1, trypsinogen-2, their α 1 -proteinase inhibitor (API) complexes, and tumour-associated trypsin inhibitor (TATI) are associated with proMMP-2 and proMMP-9 activation in ovarian tumour cyst fluids. Zymography and immunofluorometric analysis of 61 cyst fluids showed a significant association between high trypsin concentrations and the activation of MMP-9 (P = 0.003-0.05). In contrast, the trypsin concentrations were inversely associated with the activation of MMP-2 (P = 0.01-0.02). Immunohistochemical analysis of ovarian tumour tissue demonstrated expression of trypsinogen-2 and TATI in the secretory epithelium. MMP-2 was detected both in stromal and epithelial cells whereas MMP-9 was detected in neutrophils and macrophage-like cells in stromal and epithelial areas. These results suggest that trypsin may play a role in the regulation of the MMP-dependent proteolysis associated with invasion and metastasis of ovarian cancer. 1363-1371 © 2001 Cancer Research Campaign doi: 10.1054/ bjoc.2001.1806, available online at http://www.idealibrary.com on http://www.bjcancer.com aminoterminal domain for the expression of activity (Tryggvason et al, 1987). The urokinase type plasminogen activator (uPA) -plasmin system (Mazzieri et al, 1997) and membrane type MMP-1 (MT1-MMP, MMP-14) (Sato et al, 1994;Tokuraku et al, 1995) have been suggested to represent physiological mechanisms for the control of MMP-2 and MMP-9 activity. Recent studies have shown that human trypsin-2 is more potent than plasmin and other serine proteinases in activating several MMPs, including MMP-2 and MMP-9 (Sorsa et al, 1997), and that downregulation of trypsin-2 expression and activity in colon cancer cells is associated with decreased proMMP-9 activation (Lukkonen et al, 2000).In the present study we investigated the involvement of trypsin in the activation of MMP-2 and MMP-9 in vivo by studying whether the concentrations of trypsins, trypsin-API-complexes, and TATI are associated with activation of proMMP-2 and proMMP-9 in ovarian tumour cyst fluid. Furthermore, we studied the immunohistochemical expression and localization of trypsinogen-2, TATI, MMP-2, and MMP-9 in ovarian tumours.
MATERIALS AND METHODS
Clinical specimensCyst fluid samples (n = 61) were obtained from 58 patients (age range 13-79 years) undergoing surgery for removal of the tumour during 1986-1998 at Helsinki University Central Hospital. Of the tumours, 41 were benign...