Long Noncoding RNA CIR Promotes Chondrocyte Extracellular Matrix Degradation in Osteoarthritis by Acting as a Sponge For Mir-27b.

BACKGROUND/AIMS: Osteoarthritis (OA) is a degenerative joint disease characterized by articular cartilage degradation. The degradation of the extracellular matrix (ECM) of chondrocyte is closely associated with the destruction of joints in OA patients. lncRNAs are non-coding segments of RNA that possess important regulatory functions at the cellular level and in a variety of pathophysiological processes. The present study was conducted to investigate whether lncRNA-CIR regulated the expression of MMP13 as a sponge of miR-27 in OA.

METHODS: Primary cultured chondrocytes were challenged by IL-1β and TNF-α to simulate OA conditions. qRT-PCR was performed to detect the miR-27, lncRNA-CIR, MMP13 mRNA expression levels. Western blot was applied to detect MMP13 protein expression. Soluble sGAG secretion/ formation was analysed by the dimethylmethylene blue (DMMB) assay. lncRNA-CIR overexpression or inhibition was performed using overexpression plasmid and small interfering RNAs (siRNAs), respectively.

RESULTS: lncRNA-CIR significantly up-regulated in OA patients, concomitantly down-regulated miR-27 and up-regulated MMP13. Bioinformatics analysis predicted miR-27 was the target of both lncRNA-CIR and MMP13. Overexpression of lncRNA-CIR significantly increased the expression of MMP13, while miR-27 remarkably suppressed the expression of MMP13, Accompanying with the increases of mRNA level, protein level and relative luciferase activity.

CONCLUSION: The present findings indicated that lncRNA-CIR/miR-27/MMP13 axis involved in the degradation of the ECM of chondrocyte in OA.