Background and objectives: Cathepsin D (CD), an estrogen-regulated lysosomal protease, has been detected in a variety of tissues. CD expression has been correlated with the invasive potential of breast cancer, acting as an autocrine mitogen or as a protease that degrades the extracellular matrix. The role of CD expression in predicting prognosis or invasive potential in colorectal carcinomas is mostly unknown.
Methods: CD immunohistochemical expression was studied in 60 surgical specimens of colon adenocarcinomas. A three-step avidin biotinylated, horseradish immuno-peroxidase (ABC-HRP) staining technique was performed on 4 microm paraffin-embedded tissue sections with a polyclonal antibody to CD.
Results: Carcinoma cells showed positive CD immunostaining in 41.6% of adenocarcinomas (50%, 43.7%, 37.5%, and 25% of Dukes' Stage A, B, C, and D, respectively). Nonneoplastic stromal cells demonstrated positive staining in 68.3% of the adenocarcinoma specimens (37.5%, 62.5%, 91.6%, and 75% of Stage A, B, C, and D, respectively). Patients with colorectal carcinomas exhibiting simultaneously negative and positive CD expression in malignant and stromal cells, respectively, had a worse 5-year overall survival (P < 0.05). The mean 5-year survival of the 16 patients overexpressing CD in nonneoplastic stromal cells (>15% of stromal cells positive for CD) was significantly worse in comparison with the rest of the adenocarcinomas (n = 44) (27.6 +/- 4.6 vs. 46 +/- 2.7 months, respectively, P < 0.01).
Conclusions: Expression of CD immunoreactivity by the stromal cells may be associated with a more invasive phenotype. Therefore, CD expression in tumor and stromal cells may serve as an important indicator of progression and guide postoperative treatment.