Expression of miR-195 and its target gene Bcl-2 in human intervertebral disc degeneration and their effects on nucleus pulposus cell apoptosis
Abstract Objective: To investigate the expression of miR-195 and its target gene Bcl-2 in intervertebral disc degeneration (IVDD) and its effect on nucleus pulposus (NP) cell apoptosis.Methods: The expressions of miR-195 and Bcl-2 in NP tissues of IVDD patients were quantified by qRT-PCR and Western blotting respectively. NP cells were divided into Blank group, TNF-α group, TNF-α + miR-NC group, TNF-α + siBcl-2 group, and TNF-α + miR-195 inhibitors + siBcl-2 group. Cell proliferation was detected by MTT assay, cell apoptosis evaluated by flow cytometry, mitochondrial membrane potential (MMP) tested by JC-1 staining, and the expression of apoptosis-related proteins quantified by Western blotting. Results: Compared with controls, IVDD patients had significantly increased miR-195 expression and decreased Bcl-2 protein in NP tissues. The expression of miR-195 was negatively correlated with the expression of Bcl-2 in NP tissues of IVDD patients (r = - 0.89, P < 0.001). Dual-luciferase reporter gene assay indicated that Bcl-2 was a target gene of miR-195. In comparison with Blank group, TNF-α group showed decreased cell proliferation and MMP, increased cell apoptosis, up-regulated expression of miR-195, Bax and cleaved caspase 3, and down-regulated Bcl-2 protein, these changes were attenuated by miR-195 inhibitors. Additionally, siBcl-2 can reverse the protective effect of miR-195 inhibitors on TNF-α-induced NP cells. Conclusion: IVDD patients had increased miR-195 expression in NP tissues, and inhibiting miR-195 can specifically up-regulate Bcl-2 expression to curb apoptosis of TNF-α-induced NP cells.