The circ_FAM53B-miR-183-5p-CCDC6 axis modulates the malignant behaviors of papillary thyroid carcinoma cells.

Papillary thyroid carcinoma (PTC) is a common thyroid malignancy. Circular RNAs (circRNAs) have been implicated in the development of PTC. Here, we explored the function and mechanism of circRNA family with sequence similarity 53, member B (circ_FAM53B) in PTC pathogenesis. Circ_FAM53B, microRNA (miR)-183-5p and coiled-coil domain containing 6 (CCDC6) levels were gauged by quantitative reverse transcription polymerase chain reaction (qRT-PCR) or Western blotting. The direct relationship between miR-183-5p and circ_FAM53B or CCDC6 was verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Our data showed that circ_FAM53B expression was reduced in PTC tissues and cells. Circ_FAM53B expression restrained proliferation, migration, and invasion and triggered apoptosis of PTC cells, as well as hindered HUVEC tube formation. Circ_FAM53B repressed miR-183-5p expression. MiR-183-5p re-expression reversed the effects of circ_FAM53B on cell behaviors. MiR-183-5p targeted and inhibited CCDC6, and circ_FAM53B upregulated CCDC6 through miR-183-5p competition. MiR-183-5p knockdown repressed cell proliferation, migration, invasion, and tube formation and facilitated apoptosis by upregulating CCDC6. Furthermore, circ_FAM53B reduced tumor growth in vivo. Collectively, our findings suggest that circ_FAM53B affects PTC cell biological behaviors via the miR-183-5p-CCDC6 axis.