RT Journal Article SR Electronic T1 A role for 12R-lipoxygenase in MUC5AC expression by respiratory epithelial cells JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 714 OP 723 DO 10.1183/09031936.00023111 VO 40 IS 3 A1 Ignacio Garcia-Verdugo A1 Fatima BenMohamed A1 Sonja Tattermusch A1 Dominique Leduc A1 Gilles Charpigny A1 Michel Chignard A1 Mario Ollero A1 Lhousseine Touqui YR 2012 UL http://erj.ersjournals.com/content/40/3/714.abstract AB Eicosanoids are metabolites of arachidonic acid produced by cyclooxygenases (COXs) or lipoxygenases (LOXs). They mediate inflammation and mucus secretion in chronic pulmonary inflammatory diseases. The gel-forming mucin MUC5AC is over-expressed in the airways of patients with these diseases. MUC5AC expression is mediated by an extracellular signal-regulated kinase (ERK)/Sp1 dependent mechanism. Our aim was to study the role of eicosanoids and their signalling pathways in MUC5AC expression. Inhibitors of 12-LOX, but not those of COX, 5-LOX or 15-LOX, reduce MUC5AC expression induced by phorbol myristate acetate (PMA) in the bronchial epithelial cell line NCI-H292. These inhibitors also abrogate the production of whole mucus by cell monolayers. Two forms of 12-LOX (R and S) exist in mammals. Using siRNAs we show that 12R-LOX but not 12S-LOX is involved in MUC5AC expression induced by PMA, lipopolysaccharide or transforming growth factor-α. 12R-LOX also participates in MUC2 and MUC5B expression, although to a lesser extent than for MUC5AC. Contrarily, 12R-LOX silencing does not modify interleukin-8 production. 12-LOX inhibitors reduce ERK activation and Sp1 translocation induced by PMA. Moreover, the 12R-LOX product 12(R)-hydroxyeicosatetraenoic acid, induces MUC5AC expression, ERK activation and Sp1 translocation. 12R-LOX is involved in MUC5AC expression. This occurs via ERK- and Sp1-signalling pathways.