Immunohistochemical study of cyclooxygenases in prostatic adenocarcinoma; Relationship to apoptosis and Bcl-2 protein expression

Background: Cyclooxygenase (COX) is a key enzyme in the conversion of arachidonic acid to prostaglandins and other eicosanoids. A recent report has indicated a selective COX-2 inhibitor resulted in increased apoptosis and downregulated bcl-2 expression in the androgen-sensitive human prostate cancer cell. We investigated the localization of COXs in prostatic adenocarcinoma and the possible correlation of androgen blockade with its expression. Materials and Methods: The immunohistochemical expression of COX-1, COX-2 and bcl-2 protein was studied using paraffin-embedded archival tissues both before and after hormonal therapy. The number of apoptotic cells was also determined. Results: Immunohistochemistry for COX-1, not COX-2, showed the constitutive expression in the stroma of normal prostate. The expression of COX-2 protein was detected less often than that of COX-1 protein in most cases of prostatic adenocarcinoma before hormonal therapy Neoadjuvant hormonal therapy induced the expression of COX-2 protein in smooth muscle cells, fibroblasts and adenocarcinoma cells. The expression after hormonal therapy was possibly correlated with the bcl-2 protein expression. Conclusion: The present study is the first to demonstrate the immunohistochemical expression of COXs in human prostate tissue and indicated that COXs were relevant to homeostasis and tumor development of the prostate.