The Fibrinolytic Activity of Malignant Cells

Abstract

The fibrinolytic system is supposed to play a key role in the dissolution of intravascular fibrin deposits and in the prevention of thrombosis. Moreover, several pieces of evidence have emerged recently suggesting that the same system would be of importance in many other physiopathological processes. These include inflammatory responses associated with macrophage activation, cancer cell dissemination, basement membrane metabolism, myogenic differentiation, and even follicle rupture at the time of ovulation or trophoblast implantation, all processes accompanied by tissue remodeling and cell migration. It would thus appear that production of plasminogen activator (PA), the key enzyme triggering fibrinolysis, would be the most widely distributed mechanism used by cells for generating extracellular proteolysis. Several types of cells have indeed been shown able to synthesize and release a PA activity: these include normal cells such as endothelial cells, fibroblasts, smooth muscle cells, macrophages, leukocytes, and pathological cells such as malignant cells. We shall briefly review some of the most attractive pieces of information that have emerged recently regarding the fibrinolytic activity of malignant cells.