Inhibition of microRNA-۲۱ decreases the invasiveness of fibroblast-like synoviocytes in rheumatoid arthritis via TGFβ/Smads signaling pathway

Objective(s): MicroRNA-۲۱ (miR۲۱) is aberrantly elevated in rheumatoid arthritis (RA) patients, the significance of this microRNA in RA pathogenesis and treatment, however, has not been investigated. In this study, by using RA-derived fibroblast-like synoviocyte (FLS) cells as a model, we investigated the effect and corresponding mechanism of miR۲۱ inhibition on FLSs invasion. Materials and Methods:miR۲۱ expression in synovial tissue and FLSs in RA patients and non-RA controls were determined by stem-loop RT-PCR. The effect of miR۲۱ on FLSs viability and invasiveness were evaluated using miR۲۱ inhibition. Cell viability was evaluated by MTT assay and the expression of genes at mRNA and protein levels was determined by RT-PCR and Western blot, respectively. Results: Our results showed that miR۲۱ expression was highly increased in synovial tissue and FLSs in RA patients. Also, we reported that miR۲۱ inhibitor treatment could significantly suppress the invasiveness of FLSs without affecting cell viability. The decreased FLSs invasion by miR۲۱ inhibition was associated with down-regulated expression of matrix metalloproteinase (MMP)-۱, MMP۳, and MMP۱۳. Further analysis revealed that miR۲۱ inhibition could suppress the expression of TGFβ۱ and Smad۴, but promote that of Smad۷. Moreover, suppression of FLS invasion and MMPs expression by miR۲۱ treatment could be counteracted by additional TGFβ۱ treatment. Conclusion:Our results indicated that miR۲۱ inhibition can down-regulate the expression of MMP۱, MMP۳, and MMP۱۳ and consequently suppress the invasiveness of FLS, which is achieved through TGFβ۱/Smad۴/۷ signaling pathway. The findings of this study could offer a novel approach for RA treatment.

Keywords:

Fibroblast-like synoviocyte , Invasion , MicroRNA-۲۱ , Rheumatoid arthritis , Smads , Transforming growth factor-beta