title: Selective inhibition of prostacyclin synthase activity by rofecoxib.
abstract: The development of cyclooxygenase-2 (COX-2) selective inhibitors prompted studies aimed at treating chronic inflammatory diseases and cancer by using this new generation of drugs.Yet, several recent reports pointed out that long-term treatment of patients with COX-2 selective inhibitors (especially rofecoxib) caused severe cardiovascular complicances. The aim of this study was to ascertain whether, in addition to inhibiting COX-2, rofecoxib may also affect prostacyclin (PGI2) level by inhibiting PGI2 forming enzyme (prostacyclin synthase, PGIS). In order to evaluate if selective (celecoxib, rofecoxib) and non-selective (aspirin, naproxen) anti-inflammatory compounds could decrease PGI2 production in endothelial cells by inhibiting PGIS, we analyzed the effect of anti-inflammatory compounds on the enzyme activity by ELISA assay after addition of exogenous substrate, on PGIS protein levels by Western blotting and on its subcellular distribution by confocal microscopy. We also analyzed the effect of rofecoxib on PGIS activity in bovine aortic microsomal fractions enriched in PGIS. This study demonstrates an inhibitory effect of rofecoxib on PGIS activity in human umbilical vein endothelial (HUVE) cells and in PGIS-enriched bovine aortic microsomal fractions, which is not observed by using other anti-inflammatory compounds. The inhibitory effect of rofecoxib is associated neither to a decrease of PGIS protein levels nor to an impairment of the enzyme intracellular localization. The results of this study may explain the absence of a clear relationship between COX-2 selectivity and cardiovascular side effects. Moreover, in the light of these results we propose that novel selective COX-2 inhibitors should be tested on PGI2 synthase activity inhibition.
authors.affiliation: Department of Experimental Biology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Griffoni
authors.forename: Enzo
authors.initials: E
authors.lastname: Spisni
authors.forename: Antonio
authors.initials: A
authors.lastname: Strillacci
authors.forename: Mattia
authors.initials: M
authors.lastname: Toni
authors.forename: Markus Michael
authors.initials: MM
authors.lastname: Bachschmid
authors.forename: Vittorio
authors.initials: V
authors.lastname: Tomasi
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001011:Aorta / Q000737:chemistry; D002417:Cattle; D002478:Cells, Cultured; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology; D004797:Enzyme-Linked Immunosorbent Assay; D011464:Epoprostenol / Q000378:metabolism; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors*; D007783:Lactones / Q000494:pharmacology*; D008861:Microsomes / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology*; D013997:Time Factors; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D007783:Lactones; D013450:Sulfones; C116926:rofecoxib; D003577:Cytochrome P-450 Enzyme System; D011464:Epoprostenol; D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase