PT - JOURNAL ARTICLE AU - Meaghan E. Killeen AU - Joshua A. Englert AU - Donna Beer Stolz AU - Mingchen Song AU - Yusheng Han AU - Russell L. Delude AU - John A. Kellum AU - Mitchell P. Fink TI - The Phase 2 Enzyme Inducers Ethacrynic Acid, DL-Sulforaphane, and Oltipraz Inhibit Lipopolysaccharide-Induced High-Mobility Group Box 1 Secretion by RAW 264.7 Cells AID - 10.1124/jpet.105.092841 DP - 2006 Mar 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 1070--1079 VI - 316 IP - 3 4099 - http://jpet.aspetjournals.org/content/316/3/1070.short 4100 - http://jpet.aspetjournals.org/content/316/3/1070.full SO - J Pharmacol Exp Ther2006 Mar 01; 316 AB - The diuretic ethacrynic acid (EA) has been shown to inhibit signaling by the proinflammatory transcription factor nuclear factor-κB (NF-κB). Accordingly, we sought to determine whether this compound is capable of inhibiting the release of cytokines [interleukin (IL)-6 and IL-10] and NO from RAW 264.7 murine macrophage-like cells stimulated with lipopolysaccharide (LPS). Additionally, we sought to determine whether EA can inhibit secretion of high-mobility group box 1 (HMGB1), a nuclear protein that is secreted by immunostimulated macrophages and functions in the extracellular milieu as a proinflammatory mediator. In a concentration-dependent manner, EA inhibited secretion of IL-6, IL-10, nitric oxide, and HMGB1. As expected, EA inhibited NF-κB DNA binding in LPS-stimulated RAW 264.7 cells. Treating these cells with pyrrolidine dithiocarbamate, SN50 (amino acid sequence AAVALLPAVLLALLAPVQRKRQKLMP) or 5-(thien-3-yl)-3-aminothiophene-2-carboxamide (SC-514) also inhibited LPS-induced NF-κB DNA binding, but these compounds failed to inhibit LPS-induced HMGB1 secretion. These findings suggested that inhibition of HMGB1 secretion by EA might occur via a mechanism unrelated to the NF-κB signaling pathway. Because EA is an electrophilic compound that is known to be capable of inducing expression of so-called phase 2 proteins, we sought to determine whether two other phase 2 enzyme inducers, oltipraz and dl-sulforaphane, also are capable of inhibiting HMGB1 release from immunostimulated macrophages. Incubating RAW 264.7 cells with either oltipraz or dl-sulforaphane inhibited LPS-induced HMGB1 secretion. Moreover, both EA and dl-sulforaphane inhibited relocalization of nuclear HMGB1 into the cytoplasm of LPS-stimulated RAW 264.7 cells. These data suggest that phase 2 inducers may exert anti-inflammatory effects by inhibiting secretion of the cytokine-like nuclear protein HMGB1.