Tumor necrosis factor-α (TNF-α) is a major inflammatory cytokine produced by activated macrophages and lymphocytes and involved in the development of many inflammatory diseases. Preventing the production or action of TNF-α is considered as a promising therapeutic strategy for various inflammatory diseases. The resorcylic acid lactone hypothemycin has been shown to exert an antitumor activity. In this study, we studied the inhibitory effects of hypothemycin on TNF-α production and underlying mechamisms. Hypothemycin dose-dependently suppressed lipopolysaccharide (LPS)-induced TNF-α secretion without affecting LPS-induced nitric oxide (NO) production in RAW 264.7 cells. Quantitative real-time reverse transcription polymerase chain reaction analysis revealed that TNF-α mRNA expression was only slightly reduced by hypothemycin in LPS-stimulated RAW 264.7 cells. Further study demonstrated that hypothemycin down-regulated the stability of TNF-α mRNA in LPS-stimulated RAW 264.7 cells. In addition, hypothemycin suppressed the phosphorylation of p38 MAPK and ERK in LPS-stimulated RAW 264.7 cells. Knockdown of tristetraprolin (TTP), a major component of TNF-α mRNA decay machinery and direct substrate of p38 MAPK, by small interfering RNA reversed the stability of TNF-α mRNA decreased by hypothemycin treatment. Collectively, these results suggest that hypothemycin inhibits TNF-α production, at least in part, by TTP-dependent reduction of mRNA stability in LPS-stimulated RAW 264.7 cells.
- Copyright © 2013 by The American Association of Immunologists, Inc.