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 urokinase-type plasminogen activator (u-PA) levels in cell-free supernatants 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 measured 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-conditioned media, cell lines established from squamous cell carcinoma of the head and neck had significantly (P<.005) higher levels of both total 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 are able to activate plasminogen and produce u-PA in vitro. The production of PA by squamous cell carcinomas of the head and neck may play an important role in the biology of invasion and metastasis.