MOLECULAR-SPECIES OF PLASMINOGEN ACTIVATORS SECRETED BY NORMAL AND NEOPLASTIC HUMAN-CELLS

Abstract

A survey of 56 normal and neoplastic tissues has shown that plasminogen activators were released by cultured human cells in several molecular forms that could be distinguished on the basis of their MW and their susceptibility to inhibition by antibodies to the normal urinary enzyme, urokinase. Melanoma cells characteristically secreted plasminogen activators which were immunochemically distinct from urokinase and which migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a prominent, closely spaced doublet with an apparent MW of .apprx. 70,000 and a minor MW component of .apprx. 60,000. Enzymes with similar characteristics were observed in serum-free harvest fluids collected from other neoplastic tissue (a breast carcinoma, a glioblastoma, a malignant teratoma, a uterine sarcoma and a carcinoma of the renal pelvis) and from normal tissue (8 wk embryo fibroblasts, normal esophageal fibroblasts and 1 culture of normal adult bladder epithelium). Plasminogen activators released by cells derived from most normal adult tissues, from a 26 wk old embryo and from other tumors of ectodermal or mesenchymal origin were inhibited by anti-urokinase antibody and showed a closely spaced doublet with a MW of 60,000 as the most abundant molecular species with no evidence of the enzyme with a MW of 70,000.