Cathepsin D expression in renal cell cancer-clinical implications

Background: Whereas the expression of Cathepsin D (Cath D) is suggested to enhance the biological aggressiveness of human malignancies, its role in renal cell carcinoma (RCC), however, has not been investigated. Methods: By tissue microarray analysis, tumor and benign tissue samples from 176 RCC patients were investigated for Cath D expression by immunohistochemistry and Western blots. Expression levels were correlated to clinical variables and to the postoperative outcome. Results: High Cath D expression levels were detected in 29%/9% of tumor and benign tissue samples, respectively (p < 0.0001). In case of a high vs. low Cath D expression level, development of distant metastases was observed in 12% vs. 88% of cases (p < 0.05). With a median follow-up of 50 (2-146) months, high level Cath D expression was correlated with an improved long-term survival when compared with patients presenting with decreased expression [median long-term survival: 82 vs. 53 months in case of a high vs. low expression level] (p < 0.05). Conclusions: The Cath D staining pattern predicted a reduced risk for metastatic spread and tumor dependent death, hereby indicating its role as a biological variable revealing additional prognostic information for renal cell cancer patients. Increased expression of Cath D in tumor vs. benign tissue samples might indicate a role for the development and progression of RCC.