MiR-20a regulates fibroblast-like synoviocyte proliferation and apoptosis in rheumatoid arthritis.

OBJECTIVE

STAT3 expression is elevated in the synovial tissue of patients with rheumatoid arthritis (RA). MiR-20a plays a role in mediating synovial inflammation in RA. Bioinformatics analysis has identified a binding site between miR-20 and the 3'-UTR of STAT3 mRNA. This study aimed to investigate the role of miR-20a in the regulation of STAT3 expression and synovial cell proliferation as well as apoptosis.

PATIENTS AND METHODS

Synovial tissues were collected from RA patients and osteoarthritis (OA) patients to measure miR-20a, STAT3, p-STAT3, and Ki-67 expressions. Fibroblast-like synoviocytes (FLS) were treated with IL-17 (10 ng/ml) and then Ki-67 expression and cell cycle were evaluated by flow cytometry. The targeting relationship between miR-20a and STAT3 was assessed by dual luciferase reporter gene assay. FLS cells were divided into five groups: miR-NC, miR-20a mimic, si-NC, si-STAT3, and miR-20a mimic + si-STAT3 groups.

RESULTS

In RA patients, significantly lower MiR-20a expression, and substantially higher STAT3, p-STAT3, and Ki-67 expression were found in the synovial tissues compared with those in OA patients. IL-17A treatment markedly promoted FLS cell proliferation, inhibited cell apoptosis, reduced miR-20a expression, as well as upregulated levels of STAT3, p-STAT3, and Bcl-2. MiR-20a played a regulatory function on the expression of STAT3. MiR-20a mimic and/or si-STAT3 transfection apparently downregulated STAT3, p-STAT3, and Bcl-2 expression, attenuated IL-17A-induced cell proliferation promotive and enhanced cell apoptosis in FLS cells.

CONCLUSIONS

The expression of miR-20a was reduced in synovial tissue of RA patients with the increased level of STAT3. Downregulation of miR-20a promoted the expression of STAT3, p-STAT3, and Bcl-2, facilitated FLS cell proliferation, reduced apoptosis and, thereby, played a critical role in RA.