title: Activated thrombin-activatable fibrinolysis inhibitor (TAFIa) attenuates breast cancer cell metastatic behaviors through inhibition of plasminogen activation and extracellular proteolysis.
abstract: Thrombin activatable fibrinolysis inhibitor (TAFI) is a plasma zymogen, which can be converted to activated TAFI (TAFIa) through proteolytic cleavage by thrombin, plasmin, and most effectively thrombin in complex with the endothelial cofactor thrombomodulin (TM). TAFIa is a carboxypeptidase that cleaves carboxyl terminal lysine and arginine residues from protein and peptide substrates, including plasminogen-binding sites on cell surface receptors. Carboxyl terminal lysine residues play a pivotal role in enhancing cell surface plasminogen activation to plasmin. Plasmin has many critical functions including cleaving components of the extracellular matrix (ECM), which enhances invasion and migration of cancer cells. We therefore hypothesized that TAFIa could act to attenuate metastasis.
  
  
  
  To assess the role of TAFIa in breast cancer metastasis, in vitro migration and invasion assays, live cell proteolysis and cell proliferation using MDA-MB-231 and SUM149 cells were carried out in the presence of a TAFIa inhibitor, recombinant TAFI variants, or soluble TM.
  
  
  
  Inhibition of TAFIa with potato tuber carboxypeptidase inhibitor increased cell invasion, migration and proteolysis of both cell lines, whereas addition of TM resulted in a decrease in all these parameters. A stable variant of TAFIa, TAFIa-CIIYQ, showed enhanced inhibitory effects on cell invasion, migration and proteolysis. Furthermore, pericellular plasminogen activation was significantly decreased on the surface of MDA-MB-231 and SUM149 cells following treatment with various concentrations of TAFIa.
  
  
  
  Taken together, these results indicate a vital role for TAFIa in regulating pericellular plasminogen activation and ultimately ECM proteolysis in the breast cancer microenvironment. Enhancement of TAFI activation in this microenvironment may be a therapeutic strategy to inhibit invasion and prevent metastasis of breast cancer cells.
authors.affiliation: Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, N9J 3P4, Canada.
authors.forename: Zainab A
authors.initials: ZA
authors.lastname: Bazzi
authors.affiliation: Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, N9J 3P4, Canada.
authors.forename: Danielle
authors.initials: D
authors.lastname: Lanoue
authors.affiliation: Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, N9J 3P4, Canada.
authors.forename: Mouhanned
authors.initials: M
authors.lastname: El-Youssef
authors.affiliation: Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, N9J 3P4, Canada.
authors.forename: Rocco
authors.initials: R
authors.lastname: Romagnuolo
authors.affiliation: Department of Biological Sciences, University of Windsor, Windsor, ON, N9J 3P4, Canada.
authors.forename: Janice
authors.initials: J
authors.lastname: Tubman
authors.affiliation: Department of Biological Sciences, University of Windsor, Windsor, ON, N9J 3P4, Canada.
authors.forename: Dora
authors.initials: D
authors.lastname: Cavallo-Medved
authors.affiliation: Department of Biological Sciences, University of Windsor, Windsor, ON, N9J 3P4, Canada.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Porter
authors.affiliation: Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, N9J 3P4, Canada. mboffa@uwindsor.ca.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Boffa
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000556:secondary; D025901:Carboxypeptidase B2 / Q000494:pharmacology*; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D006801:Humans; D010958:Plasminogen / Q000378:metabolism*; D059748:Proteolysis; D018180:Thrombomodulin / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D018180:Thrombomodulin; D010958:Plasminogen; D025901:Carboxypeptidase B2
keywords: Breast cancer; Extracellular proteolysis; Metastasis; Plasminogen; TAFI; Thrombomodulin