Interactions between neoplastic cells with different metastasizing capacity and platelet function

Abstract

We have examined the effects on platelet function of two sublines (M 4 and M 9) derived from spontaneous lung nodules of a benzopyrene-induced murine fibrosarcoma (m FS6). The subline M 4 was more metastatic and the subline M 9 less metastatic than the primary tumour. Only the more malignant cells were able to induce irreversible aggregation of human platelets; this effect was concentration-dependent and was associated with the release of serotonin by platelets. Both aggregation and release were inhibited by preincubation of platelets with ASA, not by preincubation of the cells. The supernatants of cell suspensions had no aggregating activity. However, the neoplastic cells in culture media released an activity directly stimulating platelet aggregation and potentiating the platelet response to ADP; again, this activity was higher for the more malignant cells and the effects were inhibited by preincubation of platelets with ASA. These results suggest a role for platelets in the development of tumour metastases.