Plasminogen activators and their inhibitors in non-small cell lung cancer. Low content of type 2 plasminogen activator inhibitor associated with tumor dissemination

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Abstract
Background. Evidence suggests that plasminogen activators and their inhibitors play an important role in tumor spread. Methods. In this study, we measured the antigen levels of urokinase (u‐PA), tissue plasminogen activator (t‐PA), type 1 plasminogen activator inhibitor (PAI‐1), and type 2 plasminogen activator inhibitor (PAI‐2) in lung cancer tissue (19 adenocarcinomas and 19 squamous cell carcinomas) and normal lung tissue. Results. u‐PA, PAI‐1, and PAI‐2 antigen levels in cancer tissue were significantly higher than those in normal tissue (P < 0.001 in u‐PA and PAI‐1; P < 0.005 in PAI‐2), whereas t‐PA antigen levels in cancer tissue were significantly lower than those in normal tissue (P < 0.005). In cases with lymph node involvement (LN+ cases), PAI‐2 antigen levels were significantly lower than those in cases without lymph node involvement (LN− cases) (P < 0.02), whereas there was no difference in either u‐PA or PAI‐1 antigen levels between these two groups. Furthermore, u‐PA antigen levels showed a significant positive correlation with PAI‐2 antigen levels in LN− cases (r = 0.696; P < 0.005), although there was no correlation between these two parameters in LN+ cases. Conclusions. The antigen levels of u‐PA, PAI‐1, and PAI‐2 in cancer tissue were significantly higher than those in normal tissue, and lower content of PAI‐2 was associated with lymph node metastasis. Cancer 1994; 73:1398–405.