Differential expression profile of circRNAs in oral leukoplakia

To investigate the differences and clinical significance of circRNA expression profiles in oral leukoplakia (OLK) tissues and normal oral mucosal (NOM) tissues.

High-throughput sequencing was used to detect differentially expressed circRNAs in 6 pairs of OLK and NOM tissues, and qRT-PCR was used to verify the expression of 10 circRNAs screened in 6 pairs of OLK and NOM tissues. The ring formation of circRNA was verified by RNase R digestion and Sanger sequencing, and the target circHLA-C was further verified by qRT-PCR in 20 pairs of OLK and NOM tissues. CircHLA-C was visualized using the UCSC genome browser (genome.ucsc.edu). The function of differentially expressed circRNAs was analyzed by GO and KEGG enrichment analyses. TargetScan and miRanda predicted the downstream miRNAs and mRNAs of the target circRNAs, and a ceRNA network related to the identified circRNAs was constructed in Cytoscape.

Sequencing analysis showed that 366 circRNAs were significantly differentially expressed in OLK tissues, including 65 upregulated and 301 downregulated circRNAs. After qRT-PCR verification, 7 of the 10 screened circRNAs were expressed consistent with the sequencing results. The upregulated circHLA-C was confirmed to be a real circRNA with back-splice junction sites by RNase R digestion and Sanger sequencing. Correlation analysis showed a positive correlation between circHLA-C and the degree of OLK dysplasia. ROC curve analysis suggested that circHLA-C had potential value in diagnosing OLK with high accuracy and specificity.

CircRNA was significantly abnormally expressed in OLK tissues, and the upregulation of circHLA-C may be related to the degree of OLK dysplasia, providing guiding value for the diagnosis of OLK in the future.