Prognostic impact of urokinase-type plasminogen activator receptor (uPAR) in cytosols and pellet extracts derived from primary breast tumours

Using a previously developed enzyme-linked immunosorbent assay (ELISA), the levels of the receptor for urokinase-type plasminogen activator (uPAR) wer e determined in cytosols and corresponding membrane pellets derived from 87 8 primary breast tumours. The levels of UPAR in the pellet extracts were mo re than 3-fold higher than those measured in the cytosols (P < 0.001). More over, the uPAR levels in the two types of extracts were weakly, though sign ificantly correlated with each other (r(s) = 0.20, P < 0.001). In Cox univa riate analysis, high cytosolic levels of uPAR were significantly associated with reduced overall survival (OS) and relapse-free survival (RFS), The le vels of uPAR in pellet extracts appeared not to be related with patient sur vival. In multivariate analysis, elevated levels of uPAR measured in cytoso ls and pellet extracts were found to be independent predictors of poor OS, not RFS. The prediction of poor prognosis on the basis of high uPAR levels emphasizes its important role in plasmin-mediated degradation of extracellu lar matrix proteins during cancer invasion and metastasis. (C) 2001 Cancer Research Campaign http://www.bjcancer.com.