| 17704828 |
Fischer L, Hornig M, Pergola C, Meindl N, Franke L, Tanrikulu Y, Dodt G, Schneider G, Steinhilber D, Werz O: The molecular mechanism of the inhibition by licofelone of the biosynthesis of 5-lipoxygenase products. Br J Pharmacol. 2007 Oct;152(4):471-80. Epub 2007 Aug 20.
BACKGROUND AND PURPOSE: Licofelone is a dual inhibitor of the cyclooxygenase and 5-lipoxygenase (5-LO) pathway, and has been developed for the treatment of inflammatory diseases. Here, we investigated the molecular mechanisms underlying the inhibition by licofelone of the formation of 5-LO products. EXPERIMENTAL APPROACH: The efficacy of licofelone to inhibit the formation of 5-LO products was analysed in human isolated polymorphonuclear leukocytes (PMNL) or transfected HeLa cells, as well as in cell-free assays using respective cell homogenates or purified recombinant 5-LO. Moreover, the effects of licofelone on the subcellular redistribution of 5-LO were studied. KEY RESULTS: Licofelone potently blocked synthesis of 5-LO products in Ca (2+)-ionophore-activated PMNL (IC (50)=1.7 microM) but was a weak inhibitor of 5-LO activity in cell-free assays (IC (50)>> 10 microM). The structures of licofelone and MK-886, an inhibitor of the 5-LO-activating protein (FLAP), were superimposable. The potencies of both licofelone and MK-886 in ionophore-activated PMNL were impaired upon increasing the concentration of arachidonic acid, or under conditions where 5-LO product formation was evoked by genotoxic, oxidative or hyperosmotic stress. Furthermore, licofelone prevented nuclear redistribution of 5-LO in ionophore-activated PMNL, as had been observed for FLAP inhibitors. Finally, licofelone as well as MK-886 caused only moderate inhibition of the synthesis of 5-LO products in HeLa cells, unless FLAP was co-transfected. CONCLUSIONS AND IMPLICATIONS: Our data suggest that the potent inhibition of the biosynthesis of 5-LO products by licofelone requires an intact cellular environment and appears to be due to interference with FLAP. |
11(0,0,0,11) |