Plasminogen activator system in human breast cancer

Abstract

We measured antigen levels of 2 kinds of plasminogen activator, tissue‐type plasminogen activator (t‐PA) and uroki‐ nase‐type plasminogen activator (UK), as well as those of their primary inhibitors, type‐1 plasminogen activator inhibitor (PAI‐I) and type‐2 plasminogen activator inhibitor (PAI‐2), in tissue extracts from benign and malignant breast tumors. Tumor tissue samples from 40 fibroadenomas and 40 breast cancers were examined. t‐PA antigen levels were the same in the 2 groups. Malignant tumors contained higher levels of UK antigen than did benign tumors. In the case of breast cancer, UK antigen levels of tumors with axillary lymph‐node involvement were significantly higher than those of tumors without lymph‐ node involvement. PAI‐1 and PAI‐2 antigen levels of breast‐ cancer tissue samples were higher than those of fibroadenoma samples. PAI‐1 antigen levels of carcinomas with lymph‐node involvement were also significantly higher than those of carcinomas without node involvement. PAI‐2 antigen levels, on the contrary, were higher in carcinomas without node involvement. UK, PAI‐1 and PAI‐2 antigen levels are potentially excellent independent factors for prediction of the metastatic potential of breast cancers.