MiR-129-5p regulates cell proliferation and apoptosis via IGF-1R/Src/ERK/Egr-1 pathway in RA-fibroblast-like synoviocytes

It is reported that miR-129-5p plays an important role in various diseases, but its effect on rheumatoid arthritis (RA) and the potential mechanism remain to be clarified. In the present research, we aimed to investigate the effect of miR-129-5p on RA and the special molecular mechanism. First, the expression of miR-129-5p was analyzed in RA patients and RA Fibroblast-like synoviocytes (RA-FLSs) by RT-PCR assay. The cell viability, apoptotic rate and the relative expression of caspase-3 and caspase-8 were measured by CCK-8, Annexin-FITC/propidium iodide (PI) and ELISA, respectively. Luciferase reporter assay was performed to investigate the target of miR-129-5p. The results revealed that the expression of miR-129-5p was down-regulated in RA patients and RA-FLSs. In addition, miR-129-5p inhibited cell proliferation and induced apoptosis of RA-FLS. Furthermore, luciferase reporter assay demonstrated that insulin-like growth factor-1 receptor (IGF-1R) was the direct target of miR-129-5p, and IGF-1R promoted cell proliferation and inhibited apoptosis by activating Src/ERK/Egr-1 signaling. Furthermoremore, the Src/ERK/Egr-1 signaling pathway was suppressed by miR-129-5p. Collectively, the results of the present study suggested that miR-129-5p regulated cell proliferation and apoptosis via IGF-1R/Src/ERK/Egr-1 signaling pathway in RA.