IN-VITRO UROKINASE-TYPE PLASMINOGEN-ACTIVATOR LEVELS AND TOTAL PLASMINOGEN-ACTIVATOR ACTIVITY IN SQUAMOUS-CELL CARCINOMAS OF THE HEAD AND NECK

Objective: Determine total plasminogen activitor (PA) activity and uro kinase-type plasminogen activator (u-PA) levels in cell-free supernata nts derived from primary and metastatic squamous cell carcinoma of the head and neck. Design: Plasminogen activator activity was measured by spectrophotometric assay with chromogenic substrate Val-Leu-Lys-para- nitroanilide. Urokinase-type plasminogen activator levels were measure d with enzyme-linked immunosorbent assay technique. Results: Fourteen established squamous cell carcinoma lines from patients with head and neck cancer were assayed for both total PA activity and u-PA levels at 24 to 48 hours of incubation. Compared with control and fibroblast-co nditioned media, cell lines established from squamous cell carcinoma o f the head and neck had significantly (P<.005) higher levels of both t otal PA activity and u-PA levels. Linear regression analysis showed a positive correlation (r=.65,P=.007) between total PA activity and u-PA levels. Conclusions: Squamous cell carcinomas of the head and neck ar e able to activate plasminogen and produce u-PA in vitro. The producti on of PA by squamous cell carcinomas of the head and neck may play an important role in the biology of invasion and metastasis.