miR-338-5p Regulates the Viability, Proliferation, Apoptosis and Migration of Rheumatoid Arthritis Fibroblast-Like Synoviocytes by Targeting NFAT5.

BACKGROUND/AIMS: MicroRNAs (miRNAs) have been reported to be involved in Rheumatoid arthritis (RA) pathogenesis and prognosis. However, little is known about the disease mechanism in RA. Here, we aim to investigate the potential association between miR-338-5p and NFAT5 in RA.

METHODS: Aberrant expression of miR-338-5p in RA tissues and rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs) compared to the normal were determined by RT-qPCR. Cell viability was determined using the CCK-8 assay, and cell apoptosis was analyzed via Annexin V-FITC/PI double staining and was detected using flow cytometry. The targeted relationship was determined by TargetScan database and dual luciferase reporter gene assay.

RESULTS: Upregulation of miR-338-5p facilitated the proliferation, migration, invasion and induced G0/G1 arrest of RAFLSs while miR-338-5p inhibitor functioned oppositely. Nuclear factor of activated T-cells 5 (NFAT5) was confirmed as a downstream target of miR-338-5p which expression was directly suppressed by miR-338-5p. Overexpression of NFAT5 attenuated the proliferation and metastasis of RAFLSs and those changes could be rescued by co-transfection of miR-338-5p.

CONCLUSION: miR-338-5p promotes RAFLS's viability and proliferation, migration by targeting NFAT5, suggesting a novel therapeutic strategy for RA.