Purpose: Localized renal cell carcinoma is usually curable by nephrectomy. However, a large fraction of patients already present with metastatic disease, which results in a poor outcome. Currently no clinically relevant screening assay is available to detect early stage renal cell carcinoma. We investigated whether urinary extracellular matrix (ECM) proteins and/or matrix metalloproteinase (MMP) activity may be valuable as a noninvasive indicator of early stage renal cell carcinoma.
Materials and methods: Urine specimens from preoperative patients with renal cell carcinoma and healthy controls were collected. The urinary excretion of the ECM proteins collagen IV, laminin and fibronectin was investigated by immunoblotting. MMP activity was assessed by gelatin zymography and by a fluorescence based microtiter plate activity assay.
Results: The full-length forms of all 3 ECM proteins investigated were significantly decreased or absent in renal cell carcinoma urine. Based on criteria established in this study this finding would lead to the correct detection of 95% of patients with renal cell carcinoma (21 of 22) with a false-positive rate of 4.5% (1 of 22 controls). All 11 nonmetastatic cases of the lowest clinical stage (T1N0M0) were correctly identified. The absence of urinary ECM proteins was due to significantly increased urinary MMP activity.
Conclusions: Analysis of decreased urinary ECM proteins and analysis of increased MMP activity may have value for the development of a sensitive, high throughput molecular screening assay to detect early stage renal cell carcinoma.