MicroRNA‑25 protects nucleus pulposus cells against apoptosis via targeting SUMO2 in intervertebral disc degeneration

It has been reported that microRNA (miRNA/miR)‑25 is downregulated in patients with intervertebral disc degeneration (IVDD). However, the potential role of miR‑25 in IVDD remains unclear. Therefore, the present study aimed to investigate the effects of miR‑25 on human intervertebral disc nucleus pulposus cells (NPCs). The expression levels of miR‑25 and those of small ubiquitin‑related modifier 2 (SUMO2) were determined in human nucleus pulposus (NP) tissues by reverse transcription‑quantitative PCR (RT‑qPCR) and western blot analyses. Subsequently, the potential interaction between miR‑25 and SUMO2 was validated via dual‑luciferase reporter assay and RNA pull‑down assay with biotinylated miRNA. The effects of miR‑25 on NPC proliferation and apoptosis were evaluated using Cell Counting Kit‑8 assay, 5‑ethynyl‑2'‑deoxyuridine incorporation assay, and flow cytometry. The results showed that miR‑25 was downregulated in patients with IVDD. In addition, miR‑25 increased the proliferation of NPCs and inhibited their apoptosis. Furthermore, the current study verified that miR‑25 could directly target SUMO2 and regulate its expression via the p53 signaling pathway. Additionally, the effects of miR‑25 on NPCs were abrogated following SUMO2 overexpression. Overall, the results of the present study demonstrated that miR‑25 could promote the proliferation and inhibit the apoptosis of NPCs via targeting SUMO2, suggesting that miR‑25 may be a potential target in the treatment of IVDD.