Long non-coding RNA PVT1, a molecular sponge of miR-26b, is involved in the progression of hyperglycemia-induced collagen degradation in human chondrocytes by targeting CTGF/TGF-β signal ways

The current study was conducted to investigate the role of long non-coding RNA PVT1 in hyperglycemia-triggered human osteoarthritis (OA) chondrocytes. Cartilage from knee OA patients with and without diabetes, as well as normal cartilage, was obtained. Isolated human chondrocytes were treated with 30 nM of Glc with or without pioglitazone. The expression levels of PVT1, miR-26b, and type II collagen were determined by RT-PCR. Type II collagen was detected by immunocytochemistry and chondrocytes were stained with Alcian blue. Moreover, the interaction among PVT1, miR-26b, and CTGF was examined using bioinformatics, FISH, RIP, RNA-pull down, and luciferase reporter assays. Over-expression of PVT1 and miR-26b were performed and expressions of CTGF, TGF-β1, SMAD3, MMP-13, and type II collagen proteins were examined. Significantly higher expression of PVT1 was observed in diabetic OA. High Glc induced the elevated expression of PVT1, CTGF, TGF-β1, IL-6, and MMP-13, as well as decreased expression of type II collagen and miR-26b. These alterations could be reversed by pioglitazone. PVT1 acted as a sponge for miR-26b to facilitate CTGF expression. Over-expression of PVT1 increased the expressions of CTGF, TGF-β1, SMAD3, and MMP-13 and decreased expression of type II collagen. Our findings confirmed that PVT1 is involved in the hyperglycemia-induced collagen degradation, via the miR-26b-CTGF-TGF-β1-axis.