ABSTRACT
Two properties of fibrinogen are relevant to interactions of the plasma protein with malignant tumors. The first is the conversion of fibrinogen into fibrin, which after cross-linking by FXIII or cellular transglutaminases and retraction can form a tight barrier between the tumor and its surroundings. Secondly, fibrinogen and fibrin are potential sources of a variety of high and low molecular weight peptides endowed with potent biological activities. The results of studies on fibrinopeptide A (FPA) kinetics in patients with malignancies and the lack of heparin effect on FPA level suggest extravascular thrombin formation and conversion of fibrinogen to fibrin. Fibrin Clot Retraction (FCR)attained values close to controls in the presence of six melanoma cell lines. However, numbers of four melanoma cells required for maximal FCR were several-fold higher than those of normal fibroblasts. The relevance of the results of studies in vitro on the malignant cells’ fibrin retractile potency for the phenomena occurring in vivo is still completely unclear.
