Urokinase plasminogen activator receptor (uPAR) as a novel biomarker in prostate cancer.

183 Background: New biomarkers are warranted to distinguish between indolent and aggressive prostate cancer (PCa). The urokinase plasminogen activator receptor (uPAR) plays an important role in pericellular proteolysis by binding urokinase plasminogen activator (uPA). This is required for degradation of the extracellular matrix and for cancer invasion. In addition to binding uPAR, uPA cleaves uPAR liberating uPAR(I) and uPAR(II-III). Intact, uPAR(I-III), and uPAR(II-III) can be liberated from the cell surface resulting in three different uPAR forms in circulation. The different uPAR forms are strong prognostic markers in several cancers. We measured the uPAR forms in plasma from patients with different stages of PCa. Methods: Between February 1, 2012 and October 1, 2014, 400 patients with PCa (se table) had plasma samples obtained. The levels of intact uPAR [uPAR(I-III)], intact uPAR + cleaved uPAR domains II+III [uPAR(I-III) + uPAR(II-III)], and cleaved uPAR domain I [uPAR(I)] were determined in citrated plasma samples with two-site sandwich time-resolved fluorescence immunoassays (TR-FIAs). Results: Plasma uPAR(I-III) + uPAR(II-III) and uPAR(I) were significantly higher in hormone naïve patients and CRPC patients compared to patients with localized disease (see table). Quantification of intact uPAR(I-III) revealed no significant differences between the three groups. Conclusions: Our findings suggest that uPAR(I-III) + uPAR(II-III) and uPAR(I) are associated with higher tumor stage as well as advanced PCa disease. These associations suggest that uPAR domains in plasma harbour prognostic value for PCa patients. Further studies are warranted to validate the use of uPAR forms as biomarkers for PCa. [Table: see text]