Malignant transformation in melanocytes is associated with increased production of procoagulant microvesicles

Abstract

Shedding of microvesicles (MVs) by cancer cells is implicated in a variety of biological effects, including the establishment of cancer-associated hypercoagulable states. However, the mechanisms underlying malignant transformation and the acquisition of procoagulant properties by tumour-derived MVs are poorly understood. Here we investigated the procoagulant and prothrombotic properties of MVs produced by a melanocyte-derived cell line (melan-a) as compared to its tumourigenic melanoma counterpart Tm1. Tumour cells exhibit a two-fold higher rate of MVs production as compared to melan-a. Melanoma MVs display greater procoagulant activity and elevated levels of the clotting initiator protein tissue factor (TF). On the other hand, tumour- and melanocyte-derived MVs expose similar levels of the procoagulant lipid phosphatidylserine, displaying identical abilities to support thrombin generation by the prothrombinase complex. By using an arterial thrombosis model, we observed that melanoma- but not melanocyte-derived MVs strongly accelerate thrombus formation in a TF-dependent manner, and accumulate at the site of vascular injury. Analysis of plasma obtained from melanoma-bearing mice showed the presence of MVs with a similar procoagulant pattern as compared to Tm1 MVs produced in vitro. Remarkably, flow-cytometric analysis demonstrated that 60% of ex vivo MVs are TF-positive and carry the melanoma-associated antigen, demonstrating its tumour origin. Altogether our data suggest that malignant transformation in melanocytes increases the production of procoagulant MVs, which may contribute for a variety of coagulation-related protumoural responses.

Clinical and prognostic significance of coagulation assays in melanoma

“…It has been shown that melanoma cell lines activate prothrombin because of TF expression. Simultaneous TF expression and phosphatidylserine (PS) exposure are responsible for the highly procoagulant pattern of the aggressive melanoma cell lines [18,32,33]. CP is responsible for blood coagulation disorders in malignant neoplasms, incorrect metabolism of fibrin, and its concentration around malignant tissues.…”

Classification, Functions, and Clinical Relevance of Extracellular Vesicles

“…This activity was due to the exposure of TF, the initiator of coagulation (Bastida et al, 1984). More recently, tumor-derived vesicles exposing TF were shown to be present in peripheral blood of patients with cancer, where they have been associated with the increased risk of developing venous thromboembolism (VTE) (Tesselaar et al, 2007;Uno et al, 2007;Zwicker et al, 2009;Lima et al, 2011;Owens and Mackman, 2011). An increased concentration of microparticles is associated with an increased incidence of thrombotic events, for instance in patients with paroxysmal nocturnal hemoglobinuria, who are extremely sensitive to complement-induced lysis because of the absence of complement inhibitors (Wiedmer et al, 1993;Hugel et al, 1999;Babiker et al, 2002), and in patients with acute coronary syndromes (Mallat et al, 2000).…”

Microparticles: new light shed on the understanding of venous thromboembolism

“…Given the crucial role that MPs play in the process of VTE, the relationship between MPs and cancer has been the subject of recent studies and review articles, which have offered novel interpretations of the interaction among MPs, thrombosis and cancer [36,[75][76][77][78][79] .…”