Epigenetic silencing of miRNA-143 regulates apoptosis by targeting BCL2 in human intervertebral disc degeneration

Accumulating evidence indicates that microRNAs can regulate the apoptosis of various cells. Apoptosis of nucleus pulposus cells plays an important role in the progression of intervertebral disc degeneration. The aim of this study is to investigate whether microRNA-143 (miRNA-143) is involved in the progression of intervertebral disc degeneration. In this study, the expression of miRNA-143 and its biological modulatory effects were examined. Messenger RNA and protein expression of miRNA-143 and B-cell lymphoma-2 (BCL2) in both normal and degenerative disc tissues was determined by using RT-PCR and western-blot assays. After miRNA-143 transfection, BCL2 expression and NP cell apoptosis were assessed by using RT-PCR, western-blot, and flow cytometry. The relationship between miRNA-143 and BCL2 was assessed by bioinformatics and dual luciferase assays. Epigenetic regulation of miRNA-143 was determined by methylation-specific PCR and the effect of hypomethylation using 5-AZA. In this study, miRNA-143 expression significantly increased, while that of BCL2 decreased in degenerative disc specimens. In addition, CpG islands in the promoter region of miRNA-143 were hypomethylated in degenerative disc tissues. Furthermore, bioinformatics analysis and luciferase reporter assay indicated that BCL2 was a target gene of miRNA-143, and miRNA-143 suppressed BCL2 messenger RNA (mRNA) and protein expression. MiRNAmiRNA-143 overexpression enhances apoptosis of nucleus pulposus cells, while miRNA-143 inhibitor had the opposite effect. BCL2 knockdown reversed the effects of the miRNA-143 inhibitor on nucleus pulposus apoptosis. Our results suggest that miRNA-143 promotes the progression of nucleus pulposus apoptosis by directly targeting BCL2, providing a potential therapeutic target for the treatment of inter vertebral disc degeneration disease.