Background: The role of microparticles (MPs) in ovarian cancer and their involvement in thrombosis is poorly understood.

Aims: To identify and characterize in vitro the MPs generated by a human ovarian cell line and investigate the impact of activated protein C (APC) on their generation as well as their procoagulant activity.

Methods: The ovarian adenocarcinoma cell line (NIH-OVCAR-3) is cultured in three conditions [without stimulation, after stimulation either with protein C (PC), or with activated protein C]. Then, the microparticles generated in the supernatant, were isolated by ultracentrifugation. They were analyzed for their shape and property by several methods such as flow cytometry, electron microscopy, cryofracture analysis, DNA and RNA extraction and proteomic analysis. The level of TF on MP was evaluated by TF-induced shortening of Ca2⁺ plasma coagulation time.

Results: Our results demonstrated that 1) OVCAR-3 cells produced heterogeneous MP size 91.92%, measured less than 100nm. 2) As tested by flow cytometry, the MPs contained TF, b2 microglobulin, and annexin V. 3) MPs were generated in greater amount when cells were incubated for 18 H with APC. 4) proteomic analysis show that the MPs contain several proteins involved in cancer progression. 5) by nucleotide extraction, they contained DNA fragments, 6) cytometry analysis showed that MPs have at their surface tissue factor, which induces a shortening of Ca²⁺ -induced plasma coagulation time. When MPs are derived from stimulated cells by APC, their level of TF is increased by 20%. Curiously, in contrast with the OVCAR-3 cells, the endothelial protein C receptor was not detected in MPs using specific antibodies in flow cytometry.

Conclusions: The MPs expressed procoagulant TF activity that is increased by APC.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/activated-protein-c-up-regulates-microparticles-release-from-ovarian-cancer-cell-line/