Platelet fibronectin release induced by Walker 256 rat carcinoma tumor cells.

This study examined gel filtered rat platelet activation by Walker 256 rat carcinoma cells and characterized fibronectin release. Using aggregometry measurements, a biphasic platelet response was characterized and the timing of alpha granule release was determined. The localization and association of released platelet fibronectin with tumor cell-platelet aggregates was determined by immunofluorescent and immunocytochemical methods. The immunofluorescent studies showed that the platelet fibronectin was released and became associated with the peripheries of the tumor cells following alpha granule discharge. The ultrastructural immunocytochemical data revealed that this fibronectin was associated with a fibrin-like material, enmeshing the tumor cell-platelet aggregates. The significance of the release and localization of platelet fibronectin to tumor cell metastasis is discussed.