Arachidonic acid regulation of the cytosolic phospholipase A2α/cyclooxygenase-2 pathway in mouse endometrial stromal cells

Objective To investigate the role of arachidonic acid (AA) in mouse endometrial stromal cells. Design Experimental animal study. Setting University research laboratory. Animal(s) Sexually mature female CD1-strain mice. Intervention(s) Primary culture of endometrial stromal cells. Main Outcome Measure(s) Western blot and real-time polymerase chain reaction for gene expression and/or phophorylation analysis. Luciferase assay for Cox-2 promoter analysis. Result(s) AA-derived prostaglandins play important roles during embryo implantation and decidualization. However, the function of AA itself in reproduction is largely unknown. In this study, exogenous AA stimulated cPLA 2α phosphorylation and COX-2 expression, mainly through ERK1/2 in mouse endometrial stromal cells, and p38 inhibitor modestly inhibited cPLA 2α phosphorylation induced by AA. The induction of COX-2 by AA was diminished by short interfering RNA against C/EBPβ and inhibitory C/EBPβ (LIP). C/EBPβ binding site at −872–−864 of Cox-2 promoter contributes to Cox-2 promoter activation induced by C/EBPβ transfection. The expression of C/EBPβ protein induced by AA was inhibited by p38 inhibitor, and the phosphorylation of C/EBPβ induced by AA was inhibited by p38 inhibitor and ERK1/2 inhibitor. A nonmetabolized analogue of AA (ETYA) also enhanced cPLA 2α phosphorylation and COX-2 expression. The activation of cPLA 2α /COX-2 by AA was not inhibited by COX inhibitor indomethacin. Conclusion(s) AA can induce cPLA 2α /COX-2 pathway activation in mouse endometrial stromal cells.