Pre-operative urinary cathepsin D is associated with survival in patients with renal cell carcinoma

Abstract

BACKGROUND: No circulating markers are routinely used for renal cancer. The objective of this pilot study was to investigate whether conditioned media (CM) from renal cancer cell lines contains potential biomarkers that, when measured in clinical fluids, have diagnostic or prognostic utility. METHODS: Comparative 2D PAGE profiling of CM from renal cell carcinoma (RCC) and normal renal cultures identified cathepsin D that was subsequently validated in urine samples from 239 patients and healthy and benign disease subjects. RESULTS: Urinary cathepsin D was found to be significantly associated with overall (OS) (hazard ratio, HR, 1.33, 95%CI [1.09 -1.63], P ¼ 0.005) and cancer-specific survival (HR 1.36, 95%CI [1.07 -1.74], P ¼ 0.013) in RCC patients on univariate analysis. An optimal cut point (211 ng ml À1 mmolCr À1 ) around which to stratify patients by OS was determined. Five-year OS equal to/above and below this value was 47.0% (95%CI 35.4%, 62.4%) and 60.9% (48.8%, 76.0%), respectively. On multivariable analysis using pre-operative variables, cathepsin D showed some evidence of independent prognostic value for OS (likelihood ratio test P-value ¼ 0.056) although requiring further validation in larger patient numbers with sufficient statistical power to determine independent significance. CONCLUSION: These data establish an important proof of principle and show the potential of proteomics-based studies. Cathepsin D may be of value as a pre-operative urinary biomarker for RCC, alone or in combination.

Alterations of the serum peptidome in renal cell carcinoma discriminating benign and malignant kidney tumors

“…Urinary expression of Cathepsin D, initially observed to be altered in human cell lines by 2DE profiling, was reported as a possible independent prognostic marker [28]. SELDI strategy was used by the same group to investigate serum of RCC patients [29].…”

Urinary Proteomics—a Tool for Biomarker Discovery

“…A very interesting field in cancer biomarker discovery is tissue proteomics with definition of RCC proteomic map [29] and analysis of proteins from conditioned media of RCC cell lines. [30] However, the potential of identified proteins as biomarkers in clinical settings has to be further explored.…”

Urine Collection and Processing for Protein Biomarker Discovery and Quantification

“…Assays for bladder-tumor-associated antigen (BTA) (4) and nuclear matrix protein, NMP22, (5-7) in urine have already been approved by the FDA for bladder cancer screening. Urinary cathepsin D has been reported as a potential prognostic biomarker for renal cell carcinoma, correlating well with survival in studies utilizing mass spectrometry and immunoassays (8). Additional candidate biomarkers (9-23) for diagnosis, prognosis, and selection of treatment listed in Table 1 are in the development pipeline.…”

“…Because of the ability to create highly multiplexed assays (52), LC-MRM can be applied to a large number of potential targets informed by the existing literature, gene expression profiles, protein cataloguing experiments, i.a . Multiplexed LC-MRM assays for a number of potential protein biomarkers in urine are currently under development in our lab; peptide targets have been successfully detected for cathepsins B and D (8, 53, 54), matrix metalloproteases 9 and 13 (55-58), HBGF (59), IGFBP7 (60, 61), and osteopontin (62) from unfractionated urine protein extracts. Due to the high variability of protein concentration, the inclusion of two different stable isotope labeled peptide standards at different concentrations may be desirable or necessary for protein quantification with LC-MRM.…”