MIR-140-5p affects chondrocyte proliferation, apoptosis, and inflammation by targeting HMGB1 in osteoarthritis.

Objective: This study aimed to test the expression and biological function of miR-140-5p in osteoarthritis (OA), and identify its target gene and explore its mechanism in OA.

Methods: Differential genes were screened and analyzed by gene microarray and WGCNA analysis. The normal human chondrocytes C28/I2 were induced by IL-1β to construct the OA cell model. The expression of miR-140-5p and high mobility group box 1 (HMGB1) was quantified by quantitative real-time PCR (qRT-PCR) in OA tissues and IL-1β-induced chondrocytes. Western blotting was performed to evaluate the expression of HMGB1 and PI3K/AKT pathway activation. The concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-6, MMP-1 and MMP-3 were determined by ELISA. CCK-8 and flow cytometry were conducted to determine the cellular capabilities of proliferation and cell apoptosis.

Results: Bioinformatics analysis demonstrated that HMGB1 was highly expressed in OA and activated PI3K/AKT pathway. Also, HMGB1 was predicted as a target of miR-140-5p. The levels of miR-140-5p were negatively correlated with HMGB1 in OA tissues and IL-1β-induced chondrocytes. The overexpression of miR-140-5p reduced the expression of HMGB1 protein, p-AKT (Ser473) and p-PI3K in IL-1β-induced chondrocytes. Besides, the expression of p-AKT (Ser473) and p-PI3K was significantly upregulated by employing miR-140-5p inhibitor, but retrieved after treating with LY294002. Furthermore, miR-140-5p inhibited inflammation, matrix metalloprotease expression and apoptosis in IL-1β-induced chondrocytes through regulating HMGB1.

Conclusion: MiR-140-5p was down-regulated while HMGB1 was upregulated in OA. MiR-140-5p could inhibit the PI3K/AKT signaling pathway and suppress the progression of OA through targeting HMGB1.