Enhanced cell-associated plasminogen activator pathway but not coagulation pathway activity contributes to motility in metastatic breast cancer cells

Background: Activation of tumor cell-associated coagulation and plasminogen activator pathways occurs in malignant disease processes, including breast cancer, and may promote metastatic activity. Objectives/Methods: To compare the coagulation and plasminogen activator pathways of normal and metastatic cells, we examined two cell lines from the MCF-10 family of breast cells: near-normal immortalized MCF-10A cells, and metastatic MCF-10CA1 cells. Results: MCF-10CA1 cell motility was significantly increased as compared with that of MCF-10A cells. The two cell types supported similar rates of factor Xa generation, plasma thrombin generation, and fibrin formation. MCF-10A cells produced a stable fibrin network, whereas MCF-10CA1 cells lysed the surrounding fibrin network within 24 h of network formation. Importantly, fibrin located proximal to (within 10 μm) the MCF-10CA1 cell surface lysed substantially faster than fibrin located 100 μm from the surface. MCF-10CA1 cells supported significantly increased plasmin generation rates as compared with MCF-10A cells, providing a mechanism for the increased fibrinolytic activity of these cells towards the fibrin network. Metastatic MCF-10CA1 cells had increased expression (mRNA and protein) levels of urokinase plasminogen activator (u-PA) and decreased levels of plasminogen activator inhibitor-1 as compared with MCF-10A cells. Blocking u-PA activity with the active site-directed protease inhibitor amiloride substantially decreased MCF-10CA1 cell motility. Phosphorylated Akt levels were elevated in MCF-10CA1 cells, which partially explains the increased u-PA expression. Conclusions: These results suggest that the tumor-associated plasminogen activator pathway, not the coagulation pathway, is a key distinguishing feature between metastatic MCF10-CA1 cells and normal MCF-10A cells.