Prognostic Significance of Cathepsin-D Expression in Breast Cancer

ABSTRACT

BACKGROUND: Cathepsin D is an acid optimal protease present in a variety of normal and neoplastic tissues. Cathepsin D is an aspartylendopeptidase which is thought to be important in intracellular processes, such as protein degradation, and cathepsin D may be implicated in intracellular protein turnover. Recent evidence shows that in rabbit alveolar marcrophages, cathepsin D is synthesized as an inactive, membrane associated precursor which is then processed, via an active membrane-associated intermediate form, to an active soluble form of cathepsin D found in lysosomes and endosomes. Antibodies to cathepsin D which are suitable for immunohistochemistry have been available for approximately 20 years although the first immunohistochemical study of cathepsin D as a prognostic factor in breast cancer appeared in 1990. METHOD: The sample in this study consisted of 121 breast cancer's that had been surgically resected. Using the mouse monoclonal antibody (NCL-CDm, Novocastra Laboratories Ltd, UK) specific for the cathepsin D, we performed immunohistochemical staining by ABC methods. We examined the correlations between the expression of cathepsin D and the patient's age, the estrogen receptor status, the tumor size, the lymph node involvement, the staging, the menopausal state, the pathologic grade, the DNA ploidy, and the S-phase fraction. RESULTS: Overall, 53.7% of the patients were positive for cathepsin D. Positive staining did not correlate with age, estrogen receptor status, tumor size, axillary node status, tumor stage, monopausal status, pathologic grade, DNA ploidy, or S-phase fraction. CONCLUSIONS: The expression of cathepsin D by tumor cells was not the only significant prognostic factor of the breast cancer. We need more follow-up studies, and we need exact calculations of the survival rate.