Cytoplasmic HuR expression correlates with epithelial cancer cell but not with stromal cell cyclooxygenase-2 expression in mucinous ovarian carcinoma

Cyclooxygenase-2 (COX-2) expression has been found to associate with poor prognosis in several types of carcinomas. HuR is an mRNA stability protein and it regulates the expression of COX-2. Objectives and methods. We analyzed the expression of COX-2 and HuR in 64 mucinous ovarian carcinoma specimens by immunohistochemistry. Results. In mucinous tumors, high COX-2 protein expression was found in epithelial cancer cells in 39% (22/56) and in stromal cells in 24% (13/55) of the specimens. The expression of COX-2 in cancer cells correlated with high grade (P = 0.0285), but stromal COX-2 expression had no correlation with any clinical parameter tested. Cytoplasmic HuR protein expression was observed in cancer cells in 47% (27/57) and in stromal cells in 7% (4/56) of the mucinous tumors, and it correlated with COX-2 expression in the cancer cells (P = 0.0162) but not in the stroma. Conclusion. Our results support the hypothesis that cytoplasmic HuR is connected to COX-2 expression in ovarian carcinoma, but that its role is restricted to the transformed epithelial cancer cells. (c) 2005 Elsevier Inc. All rights reserved.