MiR-338-5p suppresses rheumatoid arthritis synovial fibroblast proliferation and invasion by targeting ADAMTS-9.

OBJECTIVES: We proposed to find out the role of miR-338-5p played in cell proliferation and invasion of rheumatoid arthritis synovial fibroblasts (RASFs) by regulating ADAMTS-9.

METHODS: QRT-PCR was performed to quantify the miR-338-5p and ADAMTS-9 mRNA expression in RA sample tissues and normal synovial tissues. Western blot was performed to evaluate the ADAMTS-9 protein levels in transfected RASFs. Luciferase reporter assays were used to demonstrate whether miR338-5p directly targets ADAMTS-9. MTT, Transwell and wound healing assays were respectively used to evaluate the growth and mobility of RASFs. Flow cytometry was applied to detect cell cycle distributions and apoptosis rates in transfected RASFs.

RESULTS: MiR-338-5p was significantly downregulated in rheumatoid arthritis (RA) tissues while ADAMTS-9 was obviously overexpressed (p<0.001). Luciferase reporter assays demonstrated that miR-338-5p directly targeted ADAMTS-9. Moreover, overexpression of miR-338-5p suppressed RASFs biological functions and induced G0/G1 arrest and apoptosis of RASFs (p<0.001), while all the effects could be efficiently attenuated by the upregulation of ADAMTS-9.

CONCLUSIONS: By inhibiting ADAMTS-9, miR-338-5p suppressed the proliferation and metastasis of rheumatoid arthritis synovial fibroblasts. Thus, replenishing miR-338-5p may be a potential therapy for the clinic management of RA.