[Usefulness of cytosolic tissue-type plasminogen activator levels in lung adenocarcinomas]

We aimed at studying the behavior of cytosol tissue-type plasminogen activator (t-PA) levels in lung adenocarcinomas and their correlation with other clinical and biological parameters.

t-PA cytosol levels were determined using EIA (Boehringer Mannheim. Germany) in 59 samples of lung adenocarcinoma and in 16 samples of normal lung tissue from the same patients. Cathepsin D, CA125, pS2, hyaluronic acid (HA), free beta subunit of chorionic gonadotropin hormone and neuron specific enolase (NSE) cytosol concentrations were determined. We also determined the concentrations of HA, erbB2 oncoprotein, epidermal growth factor receptor (EGFR), CD44s, CD44v5 and CD44v6 in cell surfaces. The following parameters were considered: clinical stage, ploidy, cellular S-phase fraction and histological grade.

In adenocarcinomas, t-PA cytosol levels ranged from 0.1 to 14.6 ng/mg prot. (median, 1.4). These levels were lower than those in normal lung tissue (r, 0.1-18.6; median, 2.95 ng/mg prot.) but did not reach statistical significance. On the other hand, t-PA concentrations decreased as the clinical stage increased and were higher in stage I than stage II-III (p = 0.080) and stage III (p = 0.0622). No significant differences of t-PA levels were observed when the histological grade, ploidy and S-phase were considered. Adenocarcinomas with high t-PA values (> 3.7 ng/mg prot., representing the 75th percentile of the whole group), had lower CA125 (p = 0.015) and erbB2 oncoprotein (p = 0.087) concentrations.

These results suggest that cytosol t-PA levels are negatively correlated with tumor size in lung adenocarcinomas. However, the usefulness of t-PA as a prognostic factor needs to be clarified in further studies.