Role of tissue factor pathway inhibitor-2 (TFPI-2) in amelanotic melanoma (C-32) invasion

Human tissue factor pathway inhibitor-2 (TFPI-2), also known as placental p rotein (PP5) and matrix-associated serine protease inhibitor (MSPI), is a 3 2-kDa extracellular matrix (ECM) protein consisting of three tandomly arran ged Kunitz-type domains that inhibits plasmin, trypsin, chymotrypsin, cathe psin G and plasma kallikrein but not urokinase and tissue-type plasminogen activators or thrombin. Earlier studies in our laboratory revealed that the production of TFPI-2 is reduced or absent during the tumor progression of human gliomas. In the present study, we investigated the role of TFPI-2 in the invasiveness of the amelanotic melanoma cell line C-32. We stably trans fected C-32 cells with a vector capable of expressing TFPI-2 in a sense ori entation (0.7 kb). TFPI-2 protein production was then determined by western blotting and the mRNA level by northern blotting in parental and stably tr ansfected (vector and sense) clones. The levels of TFPI-2 protein and mRNA were significantly higher in the sense clones, but neither was detected in parental and vector control clones. In addition, in vitro Matrigel invasion /migration assays revealed that the invasive behavior of sense clones was i nhibited compared with the behavior of parental and vector clones. This is the first study to show that the upregulation of TFPI-2 plays a significant role in reducing the invasive behavior of human amelanotic melanomas.