High levels of proteolytic enzymes in the ascitic fluid and plasma of rats rearing the Yoshida AH-130 hepatoma

Plasma and ascitic fluid of rats bearing the Yoshida ascites hepatoma AH-130 were shown to contain high levels of proteolytic enzymes belonging to different classes active at neutral and acidic pH. Relative to those measured in control rat plasma, in tumor-bearing animals, the activity levels of lysosomal cathepsins B and L, in their latent, acidic-activatable form, were approximately 5-fold higher in plasma and 9-fold higher in ascitic fluid, and cathepsin D activity was about 5-fold higher in both plasma and ascitic fluid. Plasma and ascitic fluid of tumor-bearing rats also contained novel neutral and acidic gelatinolytic activities. The latter, as revealed by zymographic analysis conducted at pH 6.0, in the presence of dithiothreitol and in the absence of divalent metal ions, was sensitive to iodoacetamide inhibition but not to EDTA, showed a molecular mass of approximately 90 kD on SDS-PAGE, and was lost upon limited proteolysis with pepsin. Therefore, this enzyme is not identifiable as cathepsin B or L or their related latent forms and may represent a novel, so far undescribed, gelatinase. Its presence exclusively in the body fluids of AH-130-bearing rats suggests its possible use as a tumor marker.