Comprehensive Circular RNA Profiling Reveals the Regulatory Role of circRNA_0007694 in Papillary Thyroid Carcinoma

PURPOSE: The present study aimed to identify differentially expressed circRNAs in thyroid cancer and verify their potential functions. METHODS: Next-generation sequencing was used to identify differentially expressed circRNAs between papillary thyroid carcinoma (PTC) tissues and paired pericarcinomatous tissues. Polymerase chain reaction and Sanger sequencing methods successfully identified hsa_circ_0007694. A hsa_circ_0007694 over-expression vector was prepared to determine the effect of this circRNA on proliferation, migration, invasion, apoptosis, and the cell cycle in PTC cells. An in vivo animal assay was conducted by injecting PTC cells into the chests of mice. Further, RNA-seq was performed, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, to verify the regulatory mechanism of hsa_circ_0007694. Western blotting was used to verify the genes thought to be involved in the hsa_circ_0007694 regulatory pathways based on KEGG analysis. RESULTS: We identified a circRNA, hsa_circ_0007694 that was down-regulated in PTC tissues compared to pericarcinomatous tissues. Over-expression of hsa_circ_0007694 promoted apoptosis and inhibited proliferation, migration, and invasion in PTC cells in vitro, and decreased tumor growth in vivo. Transcriptome sequence analysis suggested 129 differentially expressed genes between PTC tissue and paired pericarcinomatous tissue. KEGG analysis and western blotting indicated that the PI3K/AKT/mTOR and Wnt signaling networks are most likely to be related to hsa_circ_0007694 in thyroid cancer. CONCLUSION: The circRNA hsa_circ_0007694 is down-regulated in PTC and is therefore a potential therapeutic target.