• Molecules and Cells
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• v.38 no.11
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• pp.941-949
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• 2015

Rheumatoid arthritis is a chronic inflammatory disease that leads to bone and cartilage erosion. The inhibition of osteoblast differentiation by the inflammatory factor TNF-${\alpha}$ is critical for the pathogenesis of rheumatoid arthritis. To modulate TNF-${\alpha}$ mediated inhibition of osteoblast differentiation is required to improve therapeutic efficacy of rheumatoid arthritis. Here, we explored the potential role of rocaglamide-A, a component of Aglaia plant, in osteoblast differentiation. Rocaglamide-A prevented TNF-${\alpha}$ mediated inhibition of osteoblast differentiation, and promoted osteoblast differentiation directly, in both C2C12 and primary mesenchymal stromal cells. Mechanistically, Rocaglamide-A inhibited the phosphorylation of NF-${\kappa}B$ component p65 protein and the accumulation of p65 in nucleus, which resulted in the diminished NF-${\kappa}B$ responsible transcriptional activity. Oppositely, overexpression of p65 reversed rocaglamide-A's protective effects on osteoblast differentiation. Collectively, rocaglamide-A protected and stimulated osteoblast differentiation via blocking NF-${\kappa}B$ pathway. It suggests that rocaglamide-A may be a good candidate to develop as therapeutic drug for rheumatoid arthritis associated bone loss diseases.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2251-2256
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• 2015

To study effects of cellular FLICE (FADD-like IL-$1{\beta}$-converting enzyme)-inhibitory protein (c-FLIP) inhibition by RNA interference (RNAi) on sensitivity of U2OS cells to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, plasmid pSUPER-c-FLIP-siRNA was constructed and then transfected into U2OS cells. A stable transfection cell clone U2OS/pSUPER-c-FLIP-siRNA was screened from the c-FLIP-siRNA transfected cells. RT-PCR and Western blotting were applied to measure the expression of c-FLIP at the levels of mRNA and protein. The results indicated that the expression of c-FLIP was significantly suppressed by the c-FLIP-siRNA in the cloned U2OS/pSUPER-c-FLIP-siRNA as compared with the control cells of U2OS/pSUPER. The cloned cell line of U2OS/pSUPER-c-FLIP-siRNA was further examined for TRAILinduced cell death and apoptosis in the presence of a pan-antagonist of inhibitor of apoptosis proteins (IAPs) AT406, with or without 4 hrs pretreatment with rocaglamide, an inhibitor of c-FLIP biosynthesis, for 24 hrs. Cell death effects and apoptosis were measured by the methods of MTT assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and flow cytometry, respectively. The results indicated that TRAIL-induced cell death in U2OS/pSUPER-c-FLIP-siRNA was increased compared with control cells U2OS/pSUPER in the presence or absence of AT406. Flow cytometry indicated that TRAIL-induced cell death effects proceeded through cell apoptosis pathway. However, in the presence of rocaglamide, cell death or apoptotic effects of TRAIL were similar and profound in both cell lines, suggesting that the mechanism of action for both c-FLIP-siRNA and rocaglamide was identical. We conclude that the inhibition of c-FLIP by either c-FLIP-siRNA or rocaglamide can enhance the sensitivity of U2OS to TRAIL-induced apopotosis, suggesting that inhibition of c-FLIP is a good target for anti-cancer therapy.