Microparticle-associated tissue factor activity is increased in late stage lung cancer

Background: Microparticles (MP) are small (.05-1 μm) vesicles shed by cells upon activation or during apoptosis. MP are rapidly gaining importance as a new family of physiologically relevant mediators. Tissue factor (TF) is the transmembrane receptor for factor VII(a) essential in the activation of blood coagulation; TF is also involved in several pathways relevant to tumor growth and metastasis including angiogenesis, and it has been postulated that it contributes to cancer progression. Recent evidences indicate that TF circulates associated with MP. Preliminary data indicate that MP-associated TF is increased in lung cancer (LC) patients. Aim: To investigate whether MP-associated TF correlates with disease stage in LC patients. Methods: Plasma MP-TF activity was measured in 33 patients with LC of different stages. Blood was collected at the time of inclusion; MP were collected by ultracentrifugation; TF activity was measured with a one stage clotting assay. Informed consent was obtained from all patients. Results: The blood of patients with stage IV LC had a higher MP-associated TF activity compared to stage III (45.56 [14.88-143.70] vs. 9.45 [3.47-16.23] arbitrary U/mL) (median [interquartile range]); p Conclusions: MP-associated TF activity increases in late stage LC. This observation is consistent with the hypothesis that MP-associated TF is involved in LC progression.