Cardamonin Inhibits the Nuclear Translocation and DNA Binding of RelA in the Tumor Necrosis Factor-α-Induced NF-κB Signaling Pathway in Human Lung Adenocarcinoma A549 Cells.

Tumor necrosis factor α (TNF-α) activates the nuclear factor κB (NF-κB) signaling pathway, which promotes the expression of NF-κB-responsive genes, including intercellular adhesion molecule 1 (ICAM-1). We previously reported that cardamonin, a chalcone-type flavonoid, inhibited TNF-α-induced ICAM-1 expression in human lung adenocarcinoma A549 cells. However, the mechanisms by which cardamonin inhibits the TNF-α-induced NF-κB signaling pathway have yet to be elucidated. Therefore, we herein investigated the effects of cardamonin on TNF-α-induced gene expression and the NF-κB-dependent signaling pathway. Cardamonin reduced TNF-α-induced ICAM-1 mRNA expression and NF-κB reporter activity. It did not affect the inhibitor of NF-κB α (IκBα) degradation, but prevented RelA nuclear translocation and binding to the ICAM-1 promoter. Consistent with this result, three other chalcone derivatives (4'-hydroxychalcone, isoliquiritigenin, and xanthohumol) did not affect the degradation of IκBα, but inhibited nuclear RelA translocation. Cardamonin exhibited the same inhibitory profiles in human breast cancer MCF-7 cells and human fibrosarcoma HT-1080 cells. Cysteine 38 (C38) of RelA was not a primary target site of cardamonin because cardamonin inhibited the nuclear translocation of the RelA C38S mutant. An