Role of prostacyclin synthase in carcinogenesis.

Prostacyclin (PGI2 ) synthase (PGIS) and microsomal prostaglandin (PG) E synthase-1 (PGES-1) functionally couple with inducible cyclooxygenase-2 (COX-2) as their upstream enzymes to produce PGI2 and PGE2 , respectively. Non-steroidal anti-inflammatory drugs exert their pharmacological effects including antitumor effects by the inhibition of COX-2 and thereby suppress this PG biosynthesis. PGIS is abundantly expressed in vascular endothelial and smooth muscle cells and was shown to be critical for the regulation of platelet aggregation and vascular tone. In addition to its role in vascular regulation, PGIS was shown to be frequently down-regulated in several types of cancers, and the involvement of PGIS in carcinogenesis has been suggested. In this review, we summarize the current understanding of the roles of PGIS and PGIS-derived PGI2 in carcinogenesis.