CYCLOOXYGENASE 2 (COX-2) GENE ACTIVATION IS REGULATED BY CYCLIC ADENOSINE MONOPHOSPHATE

Abstract

Prostaglandin E2 production by tissue-fixed macrophages (Mphi) after severe injury contributes to an enhanced susceptibility to infection and sepsis. The purpose of this study was to investigate the effect of cyclic adenosine monophosphate (cAMP) on prostaglandin (PGE2) production and cyclooxygenase II (COX-2) gene activation in LPS-stimulated macrophages (Mphi). RAW264.7 cells, a mouse Mphi cell line, were exposed to various concentrations of dibutyryl cAMP +/- lipopolysaccharide (10 microg/mL) stimulation. Total Mphi ribonucleic acid (RNA) was harvested for the determination of COX-2 messenger RNA (mRNA) with mouse complementary deoxyribonucleic acid (cDNA) by Northern blot assay. Mphi supernatant was collected for the measurement of tumor necrosis factor (TNF) by L929 bioassay and PGE2 by enzyme-linked immunosorbent assay (ELISA), respectively. Mphi NFkappaB activity was determined by electrophoretic mobility shift assays (EMSA). Dibutyryl cAMP significantly inhibited TNF production by LPS-stimulated Mphi. Dibutyryl cAMP (1 mM) alone induced PGE2 production. Dibutyryl cAMP (100 microM and 1 mM) also augmented PGE2 production by LPS-stimulated Mphi. Dibutyryl cAMP had similar effect on Mphi COX-2 mRNA expression and NFkappaB activity. Our data demonstrate that cAMP modulates Mphi TNF production and upregulates COX-2 gene and PGE2 production.