Downregulated miR-302d-3p promotes chondrocyte proliferation and migration by regulation of Unc-51-like kinase 1

Osteoarthritis (OA) is a common musculoskeletal disease and is related to the function of chondrocytes. The aim of the present study was to investigate the effects of miR-302d-3p on chondrocytes. Quantitative PCR (qPCR) was conducted to detect mRNA expression, while western blotting was performed to investigate protein expression in these cells. RNAs mimics, inhibitors and small interfering (si)RNAs were respectively transfected into chondrocytes (CHON-001 cell line), after which, a Cell Counting Kit-8 assay was performed to detect chondrocyte viability. Giemsa staining of the cells was also conducted to analyze the colony formation ability of the cells. Additionally, cell apoptosis was evaluated with an apoptosis detection kit using flow cytometry. A scratch-wound assay was conducted to investigate cell migration. Bioinformatics analysis using TargetScan 7.2 revealed the potential the target gene of microRNA (miR)-302d-3p; a dual luciferase reporter assay determined the target gene. Suppression of miR-302d-3p increased the viability of cells, cell colony number and migration; CHON-001 cell apoptosis was also inhibited. miR-302d-3p mimics decreased the luciferase activity of reporter plasmids containing the wild-type 3′-untranslated region of Unc-51-like kinase 1 (ULK1). siULK1 decreased CHON-001 cell viability and migration. Furthermore, siULK1 promoted the expression of phosphorylated IκBα and p65, while miR-302d-3p inhibitor suppressed the expression of phosphorylated IκBα and p65. Inhibition of miR-302d-3p could promote the proliferation and migration, and inhibit the apoptosis of chondrocytes, potentially by upregulating ULK1; thus, inflammation may be suppressed. The findings of the present study suggest miR-302d-3p and ULK1 as potential therapeutic targets for the prevention and treatment of OA.