Compound FLZ inhibits lipopolysaccharide-induced inflammatory effects via down-regulation of the TAK-IKK and TAK-JNK/ p38MAPK pathways in RAW264.7 macrophages

Aim： The aim of this study was to investigate the effect of the squamosamide derivative FLZ （N-2-（4-hydroxy-phenyl）-ethyl-2-（Z,5-dimethoxy-phenyl）-3-（3-methoxy-4-hydroxy-phenyl）-acrylamide） on lipopolysaccharide （LPS）-induced inflam-matory mediator production and the underlying mechanism in RAW264.7 macrophages. Methods： RAW264.7 cells were preincubated with non-toxic concentrations of compound FLZ （1, 5, and 10 μmol/L） for 30 min and then stimulated with 10 μg/L LPS. The production of nitric oxide （NO）, the expression of inducible nitric oxide synthase （iNOS） and cyclooxygenase 2 （COX-2）, and the activation of nuclear factor kappa-B （NF-KB） and mitogen-activated protein kinase （MAPK） pathways were examined. Results： FLZ significantly inhibited the LPS-induced production of NO, as well as the expression of iNOS and COX-2 at both the RNA and the protein levels in RAW264.7 cells. The LPS-induced increase in the DNA binding activity of NF-KB and activator protein i （AP-1）, the nuclear translocation of NF-κB p65, the degradation of the inhibitory κBα protein （IκBα） and the phosphorylation of IκBα, IκB kinase （IKK） α/β, c-Jun NH2-terminal kinase （JNK） and p38 MAPKs were all suppressed by FLZ. However, the phosphorylation of extracellular signal-regulated kinase （ERK） was not affected. Further study revealed that FLZ inhibited the phosphorylation of transforming growth factor-β （TGF-β）-activated kinase 1（TAK1）, which is an upstream signaling molecule required for IKKα/β, JNK and p38 activation. Conclusion： FLZ inhibited the LPS-induced production of inflammatory mediators at least partly through the downregulation of the TAK-IKK and TAK-JNK/p38MAPK pathways.