Expression of Cathepsin D in Colorectal Carcinoma

Objective: Colorectal cancer is one of the leading causes of cancer death in both developed and developing nations. Cathepsin D, a member of the aspartic protease family, induced by estrogen, was proved to be closely correlated with poor prognosis in breast cancer, but its role in colorectal cancer is not well established. We aimed in this study to evaluate the immunohistochemical expression of Cathepsin D in colorectal carcinoma and its relation with various clinincopathologic variables. Material and Methods: Fifty paraffin embedded tissue blocks from colectomy specimens of colorectal carcinoma obtained from pathology department of Cairo University were studied immunohistochemicaly for Cathepsin D expression in tumor and stromal cells. Results: Cathepsin D expression was observed in 90% of tumor cells and 92 % of stromal cells of colorectal carcinomas. Seventy eight percent of adenocarcinomas and 100% of mucinous and signet ring cell carcinomas stained positive for Cathepsin D. The staining extent in tumor cells was <25%, 25 up to 50%, and >50% in 4%, 32% and 54% of cases respectively. Statistically significant relationship was detected between Cathepsin D expression in tumor cells and tumor differentiation (p<0.05), and between Cathepsin D expression in stromal cells and depth of tumor invasion ( p<0.01) and lymph node metastasis (p<0.05). Conclusions: The high rate of expression of Cathepsin D detected in colorectal carcinomas and the significant relationships with tumor differentiation, lymph node metastasis and depth of tumor invasion supports the hypothesis that Cathepsin D may facilitate invasion of the surrounding stroma and is used as a prognostic marker in colorectal carcinoma.