Contribution of platelets to tumor aggressivity.

e21156 Background: The interaction between cancer and coagulation process has been shown since many years. The aim of our study is to understand the mechanisms implicated and to propose new therapeutic approaches. Methods: Two breast cancer cell lines were used: a very aggressive (MDA-MB231) and a much less aggressive (MCF-7). Platelet aggregation tests were done with washed platelets, normal or fibrin removed plasma and cancer cells (20 to 2.105 cells/ml). Procoagulant activity of cancer cells was studied. Aspirin, Apyrase (ADPase), a direct thrombin inhibitor (Hirudin), two Xa inhibitors (Fondaparinux, Rivaroxaban) were the inhibitors tested. Interaction between platelets and cancer cells was visualized by confocal microscopy. Angiogenic effect of supernatants from platelets-cancer cells co-incubation was investigated. Results: The data obtained show that a platelet aggregation is induced by cancer cells in the presence of a small amount of plasma. This aggregation depends on both the type and number of...