Activation of Human Factor VII by Factors IXa and Xa on Human Bladder Carcinoma Cells

• Published in: Blood 1989-05, Vol.73 (7), p.1888-1895
• Main Authors: Wildgoose, Peter, Kisiel, Walter
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Blood Coagulation Tests - methods; Blotting, Western; Brain; Carcinoma - metabolism; Cell Line; Cell Membrane - metabolism; Chromatography, Liquid; Factor IXa; Factor VII - isolation & purification; Factor VII - metabolism; Factor Xa; Humans; Medical sciences; Micelles; Nephrology. Urinary tract diseases; Phospholipids - metabolism; Serine Endopeptidases; Tumors of the urinary system; Urinary Bladder Neoplasms - metabolism; Urinary tract. Prostate gland
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V73.7.1888.1888

Single chain factor VII is converted by limited proteolysis to its activated form, factor Vila, by a number of blood coagulation proteases including factor IXa and factor Xa. We have determined the relative rate of human factor VII activation by human factors IXa and Xa in two different systems: one containing Ca++ and human bladder carcinoma (J82) cells, and the other containing Ca + + and mixed brain phospholipids. The rate of factor VII activation was determined by a one stage coagulation assay, and proteolytic cleavage of factor VII was assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting techniques. On a molar basis, factor Xa was sixfold more efficient than factor IXaβ in activating factor VII when the activation reaction occurs on J82 cell surfaces. In contrast, when incubation takes place in a suspension of mixed phospholipids, factor Xa was 18-fold more efficient in activating factor VII than factor IXaβ. In addition, factor IXaα activated factor VII at a rate approxi- mately one-half that observed using factor IXaβ. In the absence of cells or phospholipids, no activation of factor VII by either factors IXa or Xa was observed. The addition of stoichiometric amounts of either recombinant human factor VIII (des B-domain) or plasma-derived factor Villa failed to augment the rate of factor VII activation by either factors IXaα or IXaβ. Likewise, purified human factor Va failed to influence the rate of factor VII activation by factor Xa in either system. Collectively, our studies reveal that J82 cells possess procoagulant phospholipid capable of readily supporting the activation of factor VII by either factors IXaβ or Xa. Our data also demonstrate that the relative ability of factor IXaβ and Xa to activate factor VII is significantly different when these reactions occur on tumor cell surfaces as compared with suspensions of mixed phospholipids.