Plasminogen activator inhibitor-1 accelerates lung metastasis formation of human fibrosarcoma cells.

We have studied the effects of PAI-1 on the formation of metastasis using human fibrosarcoma cells and DNA transfection. A clone (1-3C), which shows low constitutive expression of PAI-1 and low metastatic potential to the lung, was selected from human fibrosarcoma cell line HT-1080. Newly-derived clones transfected with human PAI-1 cDNA showed a 3-5 fold increase in the antigen level of PAI-1. Further, these clones demonstrated a significant increase in both the number and incidence of lung metastases when inoculated into the tail vein of athymic mice. PAI-1 could be a prognostic marker and a target for understanding the physiology of metastasis, as well as for the treatment and prevention of hematogenous lung metastasis.