COX-2 Expression and Effects of COX-2 Inhibition in Colorectal Carcinomas and their Liver Metastases

Nonsteroidal anti-inflammatory drugs are known to reduce the risk and mortality from colorectal carcinoma by inhibiting cyclo-oxygenases (COX). COX-2 expression was investigated immunohistologically in 57 patients with colorectal carcinomas and in the corresponding liver metastases using tissue microarray analysis. Ex vivo COX-2 inhibition with assessment of apoptosis was performed using precision-cut tissue slices of three human liver metastases. Following stimulation with different concentrations of the selective COX-2 inhibitor meloxicam, apoptosis was assessed immunohistochemically after 6 h and 12 h. All primary carcinomas and 56 out of the 57 liver metastases showed various degrees of cytoplasmatic COX-2 expression being with a reduction and in the liver metastases. There was a time- and concentration-dependent change in the number of apoptotic cells in tissue slices, however, this was without statistical significance. COX-2 is constantly involved in the carcinogenesis and metastatic process of colorectal cancer. The antineoplastic effect of COX-2 inhibition may be based on different pathways, including changes in sensitivity to apoptosis.