Targeting of cyclooxygenase-2 (COX-2) for cancer chemoprevention is well supported for several tumor types, most notably colon cancer. In contrast, the data for its role in prostate cancer carcinogenesis are correlative only, Thus. we compared the COX-2 expression, activity, and effects or inhibition ill prostate cancer cells on COX-2-dependent colon cancer cells. MX-2 levels in benign and malignant human prostate tissue were determined by immunohistochemistry. Compared to colon cancer cells. prostate cancer cells expressed lower levels of COX-2. produced less PGE(2) and were resistant to selective COX-2 inhibition. Examination of benign prostatic epithelium from prostatectomy samples demonstrated rare foci of COX-2. Whereas, human prostate cancer sections were uniformly negative for COX-2. In Conclusion. these studies indicate the lack of a putative role for COX-2 in prostate cancer development. Direct evidence for the involvement of COX-2 in pros tale cancer carcinogenesis is desperately needed, Published by Elsevier Inc.