Acetaminophen down-regulates interleukin-1β-induced nuclear factor-κB nuclear translocation in a human astrocytic cell line

In previous studies performed to elucidate acetaminophen mechanism of action, we demonstrated that acetaminophen inhibits prostaglandin E₂ production by interleukin (IL)-1β-stimulated T98G human astrocytic cells, without affecting cyclooxygenase-2 enzymatic activity. As this result suggests an effect at transcriptional level, we examined whether the drug interferes with the activation of nuclear factor (NF)-κB and STAT3 transcription factors and with SAPK signal transducing factor. Western blot analysis of IκBα protein in the cytoplasm of IL-1β-stimulated T98G cells and electrophoretic mobility shift assay (EMSA) on corresponding nuclear extracts indicate that acetaminophen (10-1000 μM) dose-dependently inhibits both IκBα degradation and NF-κB nuclear translocation. In the same cell type neither IL-1β-dependent SAPK activation nor IL-6-induced STAT3 phosphorylation is affected by the drug. These data indicate that therapeutic concentrations of acetaminophen induce an inhibition of IL-1β-dependent NF-κB nuclear translocation. The selectivity of this effect suggests the existence of an acetaminophen specific activity at transcriptional level that may be one of the mechanisms through which the drug exerts its pharmacological effects.