Pancreatic Ductal Adenocarcinoma Causes Bleeding Phenotype in Mice Associated with Loss of Procoagulant Activity and Increased Thrombomodulin Sensitivity

Background: Pancreatic ductal adenocarcinoma (PDAC) is associated with robust coagulation activation, which can manifest as thrombosis or bleeding. Mechanisms promoting coagulopathy in PDAC are not fully understood.

Methods: C57BL/6J mice were administered an orthotopic injection of pancreatic tumor cells derived from Kras^G12D/+, p53^R172H/+, Elas^CreER/+ mice (KPC2, KPC4580P, or KPC4684) or tissue factor (TF)-deleted KPC2 cells (KPC2-TF^KO). Coagulation biomarkers were quantified via ELISA. Thrombosis and bleeding were assessed using IVC stasis and tail transection models, respectively. Procoagulant and fibrinolytic activity in plasma were quantified by fluorogenic and turbidity assays. Gene expression in liver was quantified by RT-qPCR.

Results: Compared to controls, KPC tumor-bearing mice had increased thrombin-antithrombin complexes, but paradoxically decreased thrombus mass and prolonged bleeding times. KPC2 tumor-bearing mice had decreased thrombin generation potential with increasing tumor mass, but no change in factor IX or prothrombin gene expression. Extracellular vesicle TF activity in plasma did not differ in control and KPC2 tumor-bearing mice and loss of procoagulant potential was still observed in mice carrying KPC2-TF^KO tumors, suggesting effects were not attributable to tumor cell TF. KPC2 tumor-bearing mice had increased circulating plasmin-antiplasmin complexes, enhanced plasmin generation potential, and increased plasminogen gene expression; however, genetic deletion of plasminogen did not normalize bleeding times in KPC2 tumor-bearing mice. KPC2 tumor-bearing mice had increased fibrinogen gene expression and elevated circulating fibrinogen. Interestingly, KPC2 tumor-bearing mice also had increased thrombomodulin gene expression. Plasma from KPC2 tumor-bearing mice had increased fibrin formation in the absence of thrombomodulin, but reduced fibrin formation in the presence of thrombomodulin.

Conclusion: Tumor-bearing mice had reduced thrombosis and increased bleeding associated with a loss of plasma procoagulant activity, increased fibrinolytic potential, and elevated thrombomodulin expression. Increased thrombomodulin expression and sensitivity may suppress thrombosis in tumor-bearing mice.

No relevant conflicts of interest to declare.