CircRNA-CIDN inhibited compression-induced NP cell apoptosis and ECM degradation. (a,b) The RNA levels of circRNA-CIDN and TRIM25 in human NP cells transfected with circRNA-CIDN adenovirus or circRNA-CIDN siRNA were measured by qRT-PCR. ##p < 0.01 versus NC group, n = 3 [Student's t-test]. (c,d) Human NP cells under compression treatment were transfected with circRNA-CIDN adenovirus or circRNA-CIDN siRNA, and the expression levels of circRNA-CIDN were measured by qRT-PCR. ##p < 0.01 versus compression + NC group, n = 3 [Student's t-test]. (e-f) Human NP cells under compression were transfected with circRNA-CIDN adenovirus or circRNA-CIDN siRNA, and the protein levels of aggrecan, collagen II, MMP-3, MMP-13, Bax, Bcl-2 and c-caspase 3 were measured by western blotting. The data were normalized to GAPDH expression levels. #p < 0.05, ##p < 0.01 versus compression + NC group, n = 3 [Student's t-test]. (g-h) Human NP cells under compression were transfected with circRNA-CIDN adenovirus or circRNA-CIDN siRNA, and the rate of apoptosis was detected by Annexin V-APC/7-AAD staining. #p < 0.05 versus compression + NC group, n = 3 [Student's t-test]. Data presented as means with error bars representing standard deviation (SD).