Prostaglandins are a diverse group of autocrine and paracrine hormones that mediate many cellular and physiologic processes. Cyclooxygenase-1 (Cox-1) and cyclooxygenase-2 (Cox-2) are prostaglandin synthases that catalyze the formation of PGH2 from arachidonic acid (AA). COX2 is an inducible enzyme. It is involved in the response of cells to growth factors, tumor promoters, and cytokines that induce its expression. COX2 is induced by a wide variety of stimuli and was initially identified as immediate-early growth response gene. In addition, COX2 expression markedly increased in 85-90% of human colorectal adenocarcinoma whereas COX1 levels remain unchanged.
