A New Assay for Measurement of the Liberated Domain I of the Urokinase Receptor in Plasma Improves the Prediction of Survival in Colorectal Cancer

Abstract

BACKGROUND The liberated domain I of the urokinase plasminogen activator receptor [uPAR(I)] is a significant prognostic marker in lung and ovarian cancer, although the uPAR(I) concentration is below the limit of quantification (LOQ) in a substantial proportion of patient samples (Lung Cancer 2005;48:349–55; Clin Cancer Res 2008;14:5785–93; APMIS 2009;117:755–61). This study was undertaken to design an immunoassay with improved functional sensitivity for measuring uPAR(I) and to evaluate the prognostic value of uPAR(I) for colorectal cancer (CRC) patients. METHODS Surface plasmon resonance analysis identified 2 monoclonal antibodies, R3 and R20, that simultaneously bind to the liberated uPAR(I) but not to intact uPAR. We used R3 for capture and Eu-labeled R20 for detection in designing a 2-site sandwich time-resolved fluorescence immunoassay (TR-FIA 4) for measuring liberated uPAR(I). TR-FIA 4 was validated for use with citrated plasma. The prognostic value of the uPAR(I) concentration was evaluated in 298 CRC patients. The Cox proportional hazards model was used for the uni- and multivariate survival analyses. RESULTS The LOQ was 0.65 pmol/L. Liberated uPAR(I) was measurable in all patient samples with TR-FIA 4. In the multivariate analysis that included sex, age, tumor stage, tumor localization, and adjuvant treatment, the uPAR(I) concentration measured with TR-FIA 4 (hazard ratio, 1.72; 95% CI, 1.15–2.57; P = 0.009), as well as the concentration of intact soluble uPAR plus the cleaved uPAR fragment containing domains II and III, tumor stage, and age were independent predictors of prognosis. CONCLUSIONS TR-FIA 4 has a functional sensitivity improved 4-fold over that of the previous uPAR(I) assay. The uPAR(I) concentration measured with TR-FIA 4 is an independent predictor of prognosis in CRC patients.

The Prognostic and Predictive Value of Soluble Type IV Collagen in Colorectal Cancer: A Retrospective Multicenter Study

“…The study was a nationwide multicenter study. A total of 4,509 subjects met the initial inclusion criteria prior to endoscopy (22). Of these, endoscopy identified 298 patients with colorectal cancer, and blood samples from these patients were included in this study as the training set.…”

Inflammation and uPAR-Expression in Colorectal Liver Metastases in Relation to Growth Pattern and Neo-adjuvant Therapy

“…In tissue uPAR is mainly expressed in macrophages and myofibroblasts and some cancer cells [21]. uPAR has been shown to correlate to a poor prognosis when analysed in blood and tumour/stromal tissue from CRC patients [22][23][24][25]. In the tissue uPAR is mainly expressed in stromal cells and some cancer cells in both CRC liver metastases [21,26] and primary CRC [25].…”

Molecular Traits of the Budding Colorectal Cancer Cells

“…uPAR levels were found to constitute an independent prognostic parameter, importantly being independent of progression stage (Ganesh et al, 1994). A soluble form of uPAR, generated after enzymatic cleavage by uPA or plasmin (Hoyer-Hansen et al, 1997), can be measured in blood, and studies of plasma samples from colon cancer patients substantiate the prognostic significance of uPAR (Stephens et al, 1999;Thurison et al, 2010). As noted above, several different cell types in colon cancers express uPAR, and therefore the prognostic value of uPAR cannot be ascribed solely to the uPAR-positive budding CRC cells.…”