RESUMEN
PM2.5 is an important environmental problem threatening human health at present, which poses serious harm to human body after inhalation. J. cannabifolia is a traditional Chinese medicine which exhibits anti-inflammatory effect. This study aimed to investigate the inhibitory effect of main phenolic acid components of J. cannabifolia on inflammation caused by PM2.5. Effect of PM2.5 on cell activity and apoptosis were determined by MTT, flow cytometry and calcein AM/PI staining. PHBA, PHPAA, and mixture of PHBA and PHPAA of different concentrations were given to RAW264.7 cells pretreated with PM2.5. The effect of drugs on cellular inflammatory factors was detected by ELISA. The expressions of TLRs related signal pathway at protein and gene levels were detected by western blot and qRT-PCR. The results showed that PM2.5 had no effect on cell activity and apoptosis within the determined concentration range. PHBA and PHPAA could markly inhibit the level of IL-1ß, IL-6, and TNF-α in RAW264.7 cells. Furthermore, the expressions of TLR2, TLR4, MyD88, IRAK1, TRAF6, TAK1, IKKß, and NF-κB induced by PM2.5 were markedly inhibited by PHBA and PHPAA at protein and gene levels. This study demonstrated that PHBA and PHPAA could attenuated inflammation caused by PM2.5 through suppressing TLRs related signal pathway.
RESUMEN
AIM: The aim of this study was to investigate the mechanism of pseudolaric acid B (PLAB)-induced cell cycle arrest in human melanoma SK-28 cells. METHODS: Cell growth inhibition was detected by MTT assay, the cell cycle was analyzed by flow cytometry, and protein expression was examined by Western blot analysis. RESULTS: PLAB inhibited the growth of human melanoma cells and induced G(2)/M arrest in SK-28 cells, accompanied by an up-regulation of Cdc2 phosphorylation and a subsequent down-regulation of Cdc2 expression. Furthermore, PLAB decreased the expression of Cdc25C phosphatase and increased the expression of Wee1 kinase. Meanwhile, a reduction in Cdc2 activity was partly due to induction of the expression of p21(waf1/cip1) in a p53-dependent manner. In addition, PLAB activated the checkpoint kinase, Chk2, and increased the expression of p53, two major targets of ATM kinase. These effects were inhibited by caffeine, an ATM kinase inhibitor. We also found that PLAB significantly enhanced ATM kinase activity. CONCLUSION: Taken together, these results suggest that PLAB induced G(2)/M arrest in human melanoma cells via a mechanism involving the activation of ATM, and the effect of PLAB on Cdc2 activity was mediated via interactions with the Chk2-Cdc25C and p53 signalling pathways, two distinct downstream pathways of ATM. PLAB may be a promising chemopreventive agent for treating human melanoma.