Search

Dysfunctional Fas ligand (FasL) may inhibit the apoptosis of tumor cells. FasL contains two receptors, Fas and Decoy Receptor 3 (DcR3). DcR3 competitively binds to FasL over Fas, resulting in the inhibition of FasL-mediated apoptosis. Therefore, it was suggested that the downregulation of DcR3 expression enhances FasL-mediated apoptosis. In the current study, the expression of DcR3 was silenced in liver cancer HepG2 cells in order to study the effect of FasL on HepG2 cell activity and invasiveness. DcR3 siRNA knockdown HepG2 cells (KD), DcR3 blank plasmid control HepG2 cells and wild-type HepG2 cells (WT) were treated with FasL (10 ng/ml). Flow cytometry was used to detect changes in the cell cycle and apoptosis. MTS, clonogenic, wound healing and Transwell assays were performed to examine changes in cell activity, proliferation, migration and invasiveness. Reverse transcription polymerase chain reaction and western blot analysis were performed to measure the expression of DcR3, matrix metallopeptidase 9 (MMP9), vascular endothelial growth factor (VEGF)-C and VEGF-D. The results demonstrated that, compared with WT cells, the proportion of KD cells in the G2/M phase decreased following treatment with FasL. KD cells were more sensitive to FasL-induced apoptosis. Following treatment with FasL, the activity and proliferation, migration and invasion of KD cells were reduced, and the expression of MMP9, VEGF-C and VEGF-D decreased. Furthermore, it was demonstrated that DcR3 is involved in the proliferation and invasion of HepG2 cells, and this mechanism may be associated with the regulatory effect of the expression of MMP9, VEGF-C and VEGF-D; however, the exact mechanism of action remains unclear. FollowingDcR3 silencing, FasL-mediated apoptosis increased in HepG2 cells. Therefore, DcR3 combined with FasL may be a potential target for the treatment of liver cancer.

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation in synovial tissues. Hyperplasia of synovial tissues leads to the formation of pannus that invades the joint cartilage and bone, resulting in joint destruction. Fas ligand (FasL), which is a member of the tumor necrosis factor superfamily, contributes to the pathogenesis of autoimmune diseases, including RA. The current study attempted to identify genes whose expressions in rheumatoid fibroblast-like synoviocytes (RA-FLS) were regulated by FasL, using cDNA microarray. A total of four individual lines of primary cultured RA-FLS were incubated either with recombinant human FasL protein or PBS as an unstimulated control for 12 h. Gene expression was detected using a microarray assay. The results revealed the expression profiles of genes in RA-FLS regulated by Fas and investigated the functions of the genes that were regulated. Among the genes in this profile, the mRNA expression changes of the following genes were indicated to be of note using RT-qPCR: Dual specificity phosphatase 6, epiregulin, interleukin 11, angiopoietin-like 7, protein inhibitor of activated STAT 2 and growth differentiation factor 5. These genes may affect the pathogenesis of RA by affecting apoptosis, proliferation, cytokine production, cytokine-induced inflammation, intracellular signaling, angiogenesis, bone destruction and chondrogenesis. To the best of our knowledge, the current study is the first study to reveal the expression profile of genes in RA-FLS regulated by FasL. The data demonstrated that FasL may regulate the expression of a number of key molecules in RA-FLS, thus affecting RA pathogenesis. Further studies of the genes detected may improve the understanding of RA pathogenesis and provide novel treatment targets for RA.

Coronary heart disease is a disease characterized by coronary artery atherosclerosis lesions caused by vascular cavity stenosis, occlusion, myocardial ischemia, hypoxia or necrosis. Previous studies have demonstrated that decoy receptor-3 (DCR-3) can act as a pleiotropic immunomodulation for enhancing angiogenesis, which may be associated with the progression of coronary heart disease. In the present study, ELISA assay was used to investigate the plasma concentration level of DCR-3 in patients with coronary heart disease. The mRNA and protein level of DCR-3 in myocardial cells were determined by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. The role and molecular mechanism of DCR-3 was also evaluated in myocardial cells in mice with coronary heart disease. The role of small interfering RNA that targeted phosphoinositide 3-kinase (PI3K) in DCR-3 mediated apoptosis was confirmed by terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling and immunofluorescence. C57BL/6 mice with coronary heart disease were used to evaluate the efficacy of DCR-3 on inflammation and apoptosis. The data indicated that plasma concentration level of DCR-3 was downregulated in mice with coronary heart disease and that DCR-3 administration improved symptoms of coronary heart disease and prolonged survival of mice with coronary heart disease. In addition, it was demonstrated that DCR-3 treatment suppressed the inflammatory response and apoptosis of myocardial cells. Circulating DCR-3 concentration levels may be identified as a predictor of coronary heart disease and prognosis of coronary heart disease. Notably, it was also demonstrated that DCR-3 inhibited inflammatory factor expression levels by regulation of the PI3K/protein kinase B (AKT) signaling pathway. Taken together, these results indicate that increasing circulating DCR-3 plasma concentration is associated with degree of coronary heart disease, suggesting that DCR-3 may be a promising drug for the treatment of coronary heart disease via regulating inflammation and apoptosis through the PI3K/AKT signaling pathway.

In order to investigate the effects of RNA interference of decoy receptor 3 (DcR3) on the sensitivity of gastric cancer cells to 5-fluorouracil (5-FU) and the relevant mechanisms, siRNA against DcR3 was transfected into the gastric cancer cell line AGS. AGS cells were treated with different doses of 5-FU or for different time periods. The sensitivity of AGS cells to 5-FU was determined. The cell survival rate was detected by MTT assay. The apoptotic rate was determined by DAPI staining, and the expression of related proteins were detected by western blot analysis. The results showed that the cell survival rate was significanlty decreased in the knockdown group compared to the control group at different doses of 5-FU (P