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), and 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 case 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.