Vol. 283, Issue 2, 955-961, 1997

Inhibition of NFB-Mediated Interleukin-1-Stimulated Prostaglandin E₂ Formation by the Marine Natural Product Hymenialdisine

Amy Roshak, Jeffery R. Jackson, Marie Chabot-Fletcher and Lisa A. Marshall

Department of Immunopharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania

Exposure of human rheumatoid synovial fibroblasts (RSF) to interleukin 1 (IL-1) results in the coordinate up-regulation of 85-kDa phospholipase A₂ (PLA₂) and mitogen-inducible cyclooxygenase (COX II) and subsequent biosynthesis of prostaglandin E₂ (PGE₂). We have recently demonstrated, through the use of oligonucleotide decoys and antisense, the participation of the proinflammatory transcription factor, nuclear factor B (NFB), in the regulation of the prostanoid-metabolizing enzymes. Hymenialdisine, a marine natural product has recently been characterized as an inhibitor of NFB activation and exposure of IL-1-stimulated RSF-inhibited PGE₂ production in a concentration-dependent manner (IC₅₀ ~1 µM). Alternatively, both an analog, aldisine, and the protein kinase C inhibitor, RO 32-0432, were without affect. Direct action of hymenialdisine on IL-1-induced NFB activation was demonstrated by a significant reduction (~80%) in NFB binding to the classical B consensus motif (as assessed by electrophoretic mobility shift assay) and inhibition of stimulated p65 migration from the cytosol of treated cells (as assessed by Western analysis). Consistent with the role of NFB in the transcriptional regulation of COX II and 85-kDa PLA₂, hymenialdisine-treated RSF did not transcribe the respective mRNAs in response to IL-1. This led to reductions in their respective protein levels and subsequent reductions in the ability to produce PGE₂. Specificity of action is suggested as IL-1-stimulated interleukin-8 (IL-8) production, which is known to be an NFB-regulated event, was also inhibited by hymenialdisine, whereas IL-1-induced production of vascular endothelial growth factor, a non-NFB-regulated gene, was not affected by exposure to hymenialdisine. Taken together, hymenialdisine inhibits IL-1-stimulated-RSF PGE₂ formation acting predominately through modulation of NFB activation and offers an interesting novel tool to evaluate the role of NFB in inflammatory disease.