Immunohistochemical Analysis of Plasminogen Activators in Non-Small Cell Lung Cancer

The expression of tissue-type and urokinase-type plasminogen activators was examined in 70 non-small cell lung cancers, using an immunohistochemical method with specific monoclonal antibodies. Tissue-type plasminogen activator (TPA) was detected in cancer cells of 9 cases (13%) and in the vascular endothelium of 19 cases (27%). The expression of TPA was observed more frequently in small tumors. On the other hand, urokinase-type plasminogen activator (UPA) was detected in cancer cells of 45 cases (64%) and in stromal cells, such as vascular endothelium and fibroblast-like cells, of 44 cases (63%). In some of UPA-positive cases, the strongest staining was present in cancer cells infiltrating the stroma. Moreover, stage I disease patients with UPA-positive tumor had a worse course than UPA-negative patients. It was concluded that non-small cell lung cancer contains TPA and/or UPA in stromal cells as well as cancer cells. Our observations also suggest that UPA plays an important role in tumor invasion and evolution, providing prognostic information.