TETRANECTIN AND PLASMIN PLASMINOGEN ARE SIMILARLY DISTRIBUTED AT THE INVASIVE FRONT OF CUTANEOUS MELANOMA LESIONS/

The induction of expression of the components of the proteolytic plasm inogen activation system in cutaneous melanocytic tumour progression h as previously been reported. Plasminogen activators, their inhibitors, and the receptor for urokinase were present only in advanced primary melanomas and melanoma metastases. The present study reports on the pr esence of tetranectin and plasmin/plasminogen, two proteins connected, vith plasminogen activation, in cutaneous melanocytic lesions. The dis tribution of tetranectin and plasminogen was studied by immunohistoche mistry in 105 freshly frozen melanocytic lesions of common naevocellul ar naevi (n=24), atypical naevi (n=14), early (n=12) and advanced (n=2 0) primary melanomas, and melanoma metastases (n=35). Both tetranectin and plasminogen were detected in a variety of tissue components. In a ll stages of melanocytic tumour progression, tetranectin was found in endothelium, perivascular dendritic cells, and leukocytes. Plasminogen was present in endothelium and in the basal layer of the normal skin. Tetranectin and plasminogen staining of fibroblastic cells at the inv asive front and of extracellular matrix was, however, restricted to ma lignant lesions. Go-localization of tetranectin and plasminogen was fo und in 50 per cent of the early primary melanomas and in more than 75 per cent of the advanced melanomas and melanoma metastases. These resu lts suggest a coordinated role for tetranectin and plasminogen at the invasive front of melanomas. Tetranectin-bound plasminogen may facilit ate the migration of tumour cells.