Proliferation and apoptosis of rheumatoid arthritis fibroblast-like synoviocytes following signal transducer and activator of transcription 3 RNA interference delivery.

Abstract

In this study, we investigated the effects of delivering small interfering RNA (siRNA) for efficient STAT3 downregulation on propagation and apoptosis of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS). The FLSs were transfected with three different siRNAs. RNAi-1 was selected for further experiments. The expression levels of both STAT3 messenger RNA (mRNA) and its protein were detected by a real-time polymerase chain reaction and Western blot analysis. The proliferation of FLSs was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The apoptosis of FLSs was examined by flow cytometry. The expression levels of cell apoptotic-related genes Bcl-2, Bax, and caspase-3 were detected by Western blot analysis. RNAi-1 was selected as the RNAi group for its lowest expression levels of STAT3 mRNA. In RNAi group, the proliferation of synoviocytes was much lower and the apoptosis rate was significantly higher. FLSs of RNAi-1 group showed significantly lower expression level of apoptotic-inhibiting gene Bcl-2 and significantly higher expression levels of proapoptotic gene Bax and apoptotic protease caspase-3. Transfection with targeted STAT3 recombinant plasmids effectively inhibited the expression of STAT3 mRNA and its protein in RA-FLSs. RNAi-mediated silencing of STAT3 reduced the proliferation and promoted the apoptosis of FLSs.