Abstract: Objective To explore the role and potential mechanisms of CCAAT-enhancerbinding protein β (C / EBPβtargeted by microRNA (miR) -155 in apoptosis and inflammatory response of rat intervertebral disc chondrocytes with cervical spondylosis. Methods Forty adult maleSD rats were randomly divided into 4 groups with 10 rats in each group: Sham group, CervicalSpondylosis group, Cervical Spondylosis + C / EBPβ overexpression group, and Cervical Spondylosis + empty vector group. Rat chondrocyte cell line, atdc5 cells, were divided into 6 groups: control group, tumor necrosis factor α ( TNF-α) stimulation group, empty vector + TNF-α group, C / EBPβ overexpression + TNF-α group, mimic-NC + C / EBPβ overexpression + TNF-α group, and miR-155 mimic + C / EBPβ overexpression + TNF-α group. The expression of miR-155, apoptosis-related proteins (cleaved-caspase3, Bax, Bcl-2, PPARγ), NF-κB signaling pathway proteins (pNF-κB P65, NF-κB P65, IκB), pro-inflammatory cytokines ( TNF-α, IL-6, IL-1β), and C / EBPβ in rat cartilage tissues and atdc5 cells were detected using qRT-PCR and Western blotting experiments. Dual-luciferase reporter gene assay was conducted to determine the targeted regulatoryeffect of miR-155 on C / EBPβ expression. Results miR-155, cleaved-caspase3, Bax, PPARγ,p-NF-κB P65, TNF-α, IL-6, and IL-1β were upregulated in the Cervical Spondylosis group when compared with those in the Sham group, while Bcl-2, IκB, and C / EBPβ were downregulated inthe Cervical Spondylosis group (P< 0. 05)Ceaved-caspase3, Bax, PPARγ, p-NF-κB P65, TNF-α, IL-6, and IL-1β were downregulated in the Cervical Spondylosis + C / EBPβ overexpression group when compared with those in the Cervical Spondylosis + empty vector group, while Bcl-2, IκB, and C / EBPβ were upregulated in the Cervical Spondylosis + C / EBPβ overexpression group(P< 0. 05), but there were no significant change in miR-155 expression level (P > 0. 05). There was a significant negative correlation between the expression levels of miR-155 and C / EBPβ in thecartilage of rats with cervical spondylosis (r = - 0. 721, P < 0. 05). The TNF-α group showed upregulations of miR-155, cleaved-caspase3, Bax, PPARγ, p-NF-κB P65, IL-6, and IL-1β expression (P< 0. 05), and downregulations of Bcl-2, IκB, and C / EBPβ expression when compared with the control group (P< 0. 05). The C / EBPβ overexpression + TNF-α group showed downregulations of cleaved-caspase3, Bax, PPARγ, p-NF-κB P65, IL-6, and IL-1β expression, and upregulations of Bcl-2, IκB, and C / EBPβ expression when compared with the empty vector + TNF-α group (P < 0. 05), but no significant change was observed in miR-155 expression level ( P >0. 05). The mimic + C / EBPβ overexpression + TNF-α group showed upregulations of miR-155,cleaved-caspase3, Bax, PPARγ, p-NF-κB P65, IL-6, and IL-1β expression ( P < 0. 05), anddownregulations of Bcl-2, IκB, and C / EBPβ expression when compared with the mimic-NC + C /EBPβ overexpression + TNF-α group ( P < 0. 05). Dual-luciferase reporter gene assay confirmedCEBPβ as a target gene of miR-155 in chondrocytes. Conclusion miR-155 promotes the activationof the NF-κB signaling pathway in intervertebral disc cartilage tissues and chondrocytes in rat withcervical spondylosis by inhibiting the target gene CEBPβ, which leads to enhanced apoptosis and inflammatory response.

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