Cooperative Effect of Exogenous Heparin-Like Compounds and Secreted Glucocorticoid-Induced Inhibitor on Plasminogen Activator in 3T3 Cell Cultures

Abstract

Balb/c 3T3 cultures grown in the absence of serum release both plasminogen activator and plasminogen activator inhibitor in the culture medium. Cellular transformation with SV-40 virus increased the level of the activator, whereas dexamethasone increased the level of the inhibitor. Heparin added to the medium potentiated the glucocorticoid-induced inhibitory activity, strongly decreasing or completely abolishing the activity of plasminogen activator. Heparin sulfate showed similar effects to heparin, although at higher concentrations. It is suggested that heparin-like compounds are involved in the regulation of plasminogen activator, acting as inhibitory cofactors.