Effects of AF3442 [ N-(9-ethyl-9 H-carbazol-3-yl)-2-(trifluoromethyl)benzamide], a novel inhibitor of human microsomal prostaglandin E synthase-1, on prostanoid biosynthesis in human monocytes in vitro

• Published in: Biochemical pharmacology 2010-04, Vol.79 (7), p.974-981
• Main Authors: Bruno, Annalisa, Di Francesco, Luigia, Coletta, Isabella, Mangano, Giorgina, Alisi, Maria Alessandra, Polenzani, Lorenzo, Milanese, Claudio, Anzellotti, Paola, Ricciotti, Emanuela, Dovizio, Melania, Di Francesco, Andrea, Tacconelli, Stefania, Capone, Marta L., Patrignani, Paola
• Format: Article
• Language: English
• Subjects: Benzamides - pharmacology; Biological and medical sciences; Birth control; Carbazoles - pharmacology; Cell Line, Tumor; Dinoprostone - biosynthesis; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Epoprostenol - biosynthesis; Gynecology. Andrology. Obstetrics; Human whole blood; Humans; Inflammation; Intramolecular Oxidoreductases - antagonists & inhibitors; Lipopolysaccharides - pharmacology; Medical sciences; Microsomes - enzymology; Monocytes; Monocytes - metabolism; mPGE synthase-1; Other methods of contraception. Sterilization; PGE 2; Pharmacology. Drug treatments; Prostaglandin H2 - biosynthesis; Prostaglandin-E Synthases; Prostaglandins - biosynthesis
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2009.11.011

Inhibitors of microsomal prostaglandin (PG) E synthase-1 (mPGES-1) are being developed for the relief of pain. Redirection of the PGH 2 substrate to other PG synthases, found both in vitro and in vivo, in mPGES-1 knockout mice, may influence their efficacy and safety. We characterized the contribution of mPGES-1 to PGH 2 metabolism in lipopolysaccharide (LPS)-stimulated isolated human monocytes and whole blood by studying the synthesis of prostanoids [PGE 2, thromboxane (TX)B 2, PGF 2α and 6-keto-PGF 1α] and expression of cyclooxygenase (COX)-isozymes and down-stream synthases in the presence of pharmacological inhibition by the novel mPGES-1 inhibitor AF3442 [ N-(9-ethyl-9 H-carbazol-3-yl)-2-(trifluoromethyl)benzamide]. AF3442 caused a concentration-dependent inhibition of PGE 2 in human recombinant mPGES-1 with an IC 50 of 0.06 μM. In LPS-stimulated monocytes, AF3442 caused a concentration-dependent reduction of PGE 2 biosynthesis with an IC 50 of 0.41 μM. At 1 μM, AF3442 caused maximal selective inhibitory effect of PGE 2 biosynthesis by 61 ± 3.3% (mean ± SEM, P < 0.01 versus DMSO vehicle) without significantly affecting other prostanoids (i.e. TXB 2, PGF 2α and 6-keto-PGF 1α). In LPS-stimulated whole blood, AF3442 inhibited in a concentration-dependent fashion inducible PGE 2 biosynthesis with an IC 50 of 29 μM. A statistically significant inhibition of mPGES-1 activity was detected at 10 and 100 μM (38 ± 14%, P < 0.05, and 69 ± 5%, P < 0.01, respectively). Up to 100 μM, the other prostanoids were not significantly affected. In conclusion, AF3442 is a selective mPGES-1 inhibitor which reduced monocyte PGE 2 generation also in the presence of plasma proteins. Pharmacological inhibition of mPGES-1 did not translate into redirection of PGH 2 metabolism towards other terminal PG synthases in monocytes. The functional relevance of this observation deserves to be investigated in vivo.