Confirmation and preliminary analysis of circRNAs potentially involved in human intervertebral disc degeneration

Circular RNAs (circRNAs) are relatively recently identified noncoding RNAs that are ubiquitously expressed in human tissues and serve key functions in regulating gene expression. However, few studies have focused on human intervertebral disc degeneration (IDD) circRNAs, and the potential role of circRNAs in IDD has not been described in detail. In the present study, circRNA expression data was downloaded from the Gene Expression Omnibus database, and circRNAs in the human intervertebral disc were classified according to their length, indicating their uniform distribution of circRNAs of different lengths. Gene Ontology analysis was performed, which indicated that the differentially expressed circRNAs were mainly produced as a result of catalytic activity and from binding genes in the molecular function category, cell part genes in the cellular component category, and cellular and metabolic process genes in the biological process category. Classification analysis divided the circRNAs host genes into 16 classes; with nucleic acid binding genes ranked as the most common host gene type in IDD tissue. Pathway analysis indicated that >15 signaling pathways may serve different roles in IDD, and Wnt signaling, gonadotropin‑releasing hormone receptor and integrin signaling pathways may serve important roles. Using co‑expression analysis, 76 differentially expressed circRNAs and host gene pairs were identified, which were divided into four groups: CircRNAs and their host genes downregulated; circRNAs downregulated and host genes upregulated; circRNAs and their host genes upregulated; and circRNAs upregulated and host genes downregulated. Finally, hsa_circ_0008305 upregulation and hsa_circ_0041946 downregulation were validated in IDD using reverse transcription‑quantitative polymerase chain reaction. In conclusion, the findings of the present study may shed light on the potential roles of circRNAs in IDD and the possibility for their use in the diagnosis and clinical treatment of IDD in the future.