CYCLOOXYGENASE AND COLON-CANCER - CLUES TO THE ASPIRIN EFFECT

Epidemiological and experimental studies indicate an inverse relations hip between the risk of colon cancer development and intake of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), All NSAIDs a re known inhibitors of cyclo-oxygenase, the enzyme responsible for con verting arachidonic acid to prostaglandins. Prostaglandins have been i mplicated in the pathogenesis of colon cancer and it has been suggeste d that the preventive effect of NSAIDs is due to inhibition of cyclo-o xygenase activity. Cyclo-oxygenase exists in two different isoforms, c yclo-oxygenase-1 and cyclo-oxygenase-2, and data obtained during the l ast few years have suggested that cyclo-oxygenase-2 might be involved in both human and experimental colon carcinogenesis, The purpose of th is review is to provide an update on recent studies regarding cyclo-ox ygenase, in particular cyclo-oxygenase-2, in relation to colon cancer in humans and in experimental models.