Fibrinolysis Associated with Oncogenic Transformation

Abstract

Abstract The cell factor that is involved in tumor-associated fibrinolysis has been partially purified from the supernatant fluid of transformed chicken embryo fibroblast cultures. It is an arginine-specific protease that acts as a plasminogen activator. The molecular weight is approximately 39,000, and the irreversible inhibitory effect of diisopropyl fluorophosphate suggests it is a serine enzyme. The cell factor that is detected in the supernatant culture fluid also occurs in a cell-associated form in transformed but not in normal cells. This form is tightly bound in a postnuclear cellular particulate fraction and can be solubilized by sodium dodecyl sulfate or Triton X-100. The cell factor activates plasminogen by proteolytic cleavage, and it acts preferentially on one of two electrophoretic classes of plasminogen molecules found in chicken plasma.