CircRNA circ-ITCH suppresses papillary thyroid cancer progression through miR-22-3p/CBL/β-catenin pathway.

While recent evidence has uncovered that circular RNAs (circRNAs) are vital regulators of carcinogenesis, their role in papillary thyroid cancer (PTC) is not clearly understood. In this study, we reveal that lower levels of circRNA circ-ITCH are expressed in PTC tissues than in normal adjacent tissues. Gain-of-functional assays show that circ-ITCH overexpression suppresses PTC cell proliferation and invasion and promotes apoptosis in vitro. Overexpression of circ-ITCH also leads to impaired tumor growth in vivo. Bioinformatics analysis and luciferase reporter assays demonstrate that circ-ITCH sponges miR-22-3p to upregulate the expression of CBL, an E3 ligase of nuclear β-catenin. Elevated levels of CBL suppress activation of the Wnt/β-catenin pathway and consequently attenuates PTC progression. In summary, our study reveals a novel signaling pathway of circ-ITCH/miR-22-3p/CBL/β-catenin involved in PTC development and progression.