title: 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.
authors.affiliation: Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Luize G
authors.initials: LG
authors.lastname: Lima
authors.forename: Andreia S
authors.initials: AS
authors.lastname: Oliveira
authors.forename: Luiza C
authors.initials: LC
authors.lastname: Campos
authors.forename: Martin
authors.initials: M
authors.lastname: Bonamino
authors.forename: Roger
authors.initials: R
authors.lastname: Chammas
authors.forename: Claudio
authors.initials: C
authors.lastname: Werneck
authors.forename: Cristina P
authors.initials: CP
authors.lastname: Vicente
authors.forename: Marcello A
authors.initials: MA
authors.lastname: Barcinski
authors.forename: Lars C
authors.initials: LC
authors.lastname: Petersen
authors.forename: Robson Q
authors.initials: RQ
authors.lastname: Monteiro
mesh_terms: D000818:Animals; D001777:Blood Coagulation; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D055252:Cell-Derived Microparticles / Q000378:metabolism* / Q000473:pathology; D003029:Coagulants / Q000378:metabolism; D006801:Humans; D008544:Melanocytes / Q000378:metabolism* / Q000473:pathology / Q000637:transplantation; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D010949:Plasma / Q000378:metabolism; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D019851:Thrombophilia; D013925:Thromboplastin / Q000378:metabolism*; D013927:Thrombosis; D059016:Tumor Microenvironment
chemical_list: D003029:Coagulants; D013925:Thromboplastin