Prognostic impact of urokinase-type plasminogen activator system components in clear cell renal cell carcinoma patients without distant metastasis

BMC Cancer. 2014 Dec 18:14:974. doi: 10.1186/1471-2407-14-974.

Abstract

Background: Members of the urokinase-type plasminogen activator (uPA) system including uPA, its receptor uPAR and the plasminogen activator inhibitor 1 (PAI-1) play an important role in tumour invasion and progression in a variety of tumour types. Since the majority of clear cell renal cell carcinoma (ccRCC) shows distant metastasis at time of diagnosis or later, the interplay of uPA, uPAR and PAI-1 might be of importance in this process determining the patients' outcome.

Methods: Corresponding pairs of malignant and non-malignant renal tissue specimens were obtained from 112 ccRCC patients without distant metastasis who underwent tumour nephrectomy. Tissue extracts prepared from fresh-frozen tissue samples by detergent extraction were used for the determination of antigen levels of uPA, uPAR and PAI-1 by ELISA. Antigen levels were normalised to protein concentrations and expressed as ng per mg of total protein.

Results: Antigen levels of uPA, uPAR, and PAI-1 correlated with each other in the malignant tissue specimens (rs=0.51-0.65; all P<0.001). Antigen levels of uPA system components were significantly higher in tissue extracts of non-organ confined tumours (pT3+4) compared to organ-confined tumours (pT1+2; all P<0.05). Significantly elevated levels of uPAR and PAI-1 were also observed in high grade ccRCC. When using median antigen levels as cut-off points, all three uPA system factors were significant predictors for disease-specific survival (DSS) in univariate Cox's regression analyses. High levels of uPA and uPAR remained independent predictors for DSS with HR=2.86 (95% CI 1.07-7.67, P=0.037) and HR=4.70 (95% CI 1.51-14.6, P=0.008), respectively, in multivariate Cox's regression analyses. A combination of high antigen levels of uPA and/or uPAR further improved the prediction of DSS in multivariate analysis (HR=14.5, 95% CI 1.88-111.1, P=0.010). Moreover, high uPA and/or uPAR levels defined a patient subgroup of high risk for tumour-related death in ccRCC patients with organ-confined disease (pT1+2) (HR=9.83, 95% CI 1.21-79.6, P=0.032).

Conclusions: High levels of uPA and uPAR in tumour tissue extracts are associated with a significantly shorter DSS of ccRCC patients without distant metastases.

MeSH terms

  • Aged
  • Antigens / analysis
  • Carcinoma, Renal Cell / chemistry*
  • Carcinoma, Renal Cell / mortality
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Kidney / chemistry
  • Kidney Neoplasms / chemistry*
  • Kidney Neoplasms / mortality
  • Male
  • Middle Aged
  • Plasminogen Activator Inhibitor 1 / analysis*
  • Plasminogen Activator Inhibitor 1 / immunology
  • Predictive Value of Tests
  • Prognosis
  • Receptors, Urokinase Plasminogen Activator / analysis*
  • Receptors, Urokinase Plasminogen Activator / immunology
  • Survival Rate
  • Urokinase-Type Plasminogen Activator / analysis*
  • Urokinase-Type Plasminogen Activator / immunology

Substances

  • Antigens
  • Plasminogen Activator Inhibitor 1
  • Receptors, Urokinase Plasminogen Activator
  • Urokinase-Type Plasminogen Activator