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Aim To study the inhibitory effect of isoquercitrin on Raf/MEK/ERK signaling pathway in HepG2 cells.Methods MTT was used to detect the proliferation of human liver cancer HepG2 cells after the treatment of isoquercitrin.The morphology and growth of cells were observed under inverted microscope after the different concentrations of isoquercitrin(0, 40, 80, 160, 320 μmol·L-1) to treat HepG2 cells for 24 and 48 h.Cell cycle was assessed by flow cytometry.Ras, Raf, MEK, ERK expression was assayed by Western blot, and mRNA expression was detected by quantitative fluorescence PCR.Results Isoquercitrin could inhibit the growth of HepG2 cells in a concentration-and time-dependent manner.Typical morphological changes of apoptosis were observed by inverted microscopy after HepG2 cells were treated with different concentrations of of isoquercitrin for 24 h or 48 h.The cell cycle assay showed that with the increasing concentration of isoquerditrin, the number of cells that was arrested in G1 phase gradually increased.Compared with the blank group, the expressions of Ras, Raf, MEK, ERK mRNA were down-regulated, and related proteins expression were also down-regulated(P<0.05), and these results had statistical significance.Conclusion Isoquercitrin can induce the apoptosis of HepG2 cells, which may be related to the Raf/MEK/ERK signaling pathway.
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Objective To investigate whetherthe extract of HUANGPI inhibitthe secretion of TNF-αvia TLR4/MyD88/TRAF6 signaling pathway. Methods ELISA assay was performed to determine TNF-α level in cell culture medium. MTT assay was used to detect the effects of the extract of HUANGPI and LPS on the viabilities of RAW 264.7 cells. Proteinexpressions of TLR4 and TRAF6 were detected by Western blotting assay. Results The extract of HUANGPI inhibited the secretion of TNF-αin a dose-dependent manner. Compared to LPS group , were TNF-αwas significantly suppressed in the cells in LPS+MyD88 inhibitor group , LPS+extract group and LPS+extract+MyD88 inhibitor group,with the corresponding reductions of TLR4 and TRAF6 protein expression at74% and21%,70% and27%,44% and8.5%, respectively. Conclusion MYD88-dependent signaling pathway might be involved in the mechanism underlying the effect of the extract of HUANGPI on suppressing LPS-induced inflammation.