Fibrinolysis-inhibitory activity of cultured human cancer cell lines.

Fibrinolysis-inhibitory activity was estimated in the lysates of 21 lines of cultured human cancer cells, from which plasminogen activator activity had veen effectively eliminated by affinity chromatography. Inhibitory activity against urokinase varied from one line to another. Three lines of lung cancer and 1 line of urinary bladder cancer showed high inhibitory activity against urokinase. Two lines of lung cancer, 3 lines of gastric cancer, 1 line of renal cancer and 1 line of renal pelvic cancer showed moderate inhibitory activity. Since inhibitory activity against plasmin was not apparent in all the cell lines tested, this activity seemed to be directed selectively towards urokinase. No inhibitory activity against urokinase was detected in 4 lines of lung cancer, 5 lines of gastric cancer and 1 line of renal cancer. There was no specific correlation between the degree of inhibitory activity against urokinase and the histological cell types of the original tumors of the cultured cell lines.