title: The chemotherapy metabolite acrolein upregulates thrombin generation and impairs the protein C anticoagulant pathway in animal-based and cell-based models.
abstract: BACKGROUND
  Thrombosis is a common complication in cancer patients receiving chemotherapy regimens that include cyclophosphamide. However, the mechanisms by which these agents increase this risk are largely uncharacterized.
  
  
  OBJECTIVE
  To examine the effects of cyclophosphamide and its metabolite acrolein on procoagulant and anticoagulant pathways in both cell-based and animal-based models.
  
  
  METHODS
  Thrombin and activated protein C (APC) generation were measured in defibrinated plasma exposed to acrolein-treated endothelial and smooth muscle cells. Tissue factor (TF) activity was measured on acrolein-treated cells. Cell surface levels of phosphatidylserine, TF, endothelial protein C receptor and thrombomodulin were measured. Healthy BALB/c mice received injections of saline (control), acrolein, or cyclophosphamide; blood was collected, and plasma thrombin-antithrombin (TAT) complex, protein C and APC levels were analyzed.
  
  
  RESULTS
  Exposure of acrolein-treated endothelial and smooth muscle cells to defibrinated plasma increased thrombin generation in the plasma. This was associated with enhanced phosphatidylserine exposure and/or increased TF activity on acrolein-treated cells. Despite elevated levels of thrombin generation, plasma APC levels were not elevated. In vivo, treatment of mice with cyclophosphamide and acrolein resulted in elevations of plasma TAT complex levels, whereas APC levels remained low.
  
  
  CONCLUSIONS
  This is the first study to examine thrombin generation and the APC pathway in chemotherapy-treated mice. Cyclophosphamide and acrolein appear to upregulate procoagulant pathways, while impairing endogenous anticoagulant pathways. This may explain, in part, the increased risk of thrombosis observed in cancer patients receiving cyclophosphamide-containing chemotherapy.
authors.affiliation: Department of Medical Sciences, McMaster University, Hamilton, ON, Canada.
authors.forename: L L
authors.initials: LL
authors.lastname: Swystun
authors.forename: S
authors.initials: S
authors.lastname: Mukherjee
authors.forename: M
authors.initials: M
authors.lastname: Levine
authors.forename: P C
authors.initials: PC
authors.lastname: Liaw
mesh_terms: D000171:Acrolein / Q000494:pharmacology*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D003520:Cyclophosphamide / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008962:Models, Theoretical; D011486:Protein C / Q000037:antagonists & inhibitors*; D013917:Thrombin / Q000096:biosynthesis*; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; D011486:Protein C; D000171:Acrolein; D003520:Cyclophosphamide; D013917:Thrombin