Circ_0000144 facilitates the progression of thyroid cancer via the miR-217/AKT3 pathway.

Background: Thyroid carcinoma (TC) is the most common malignancy of the endocrine system. Circular RNA (circRNA) is vital in the regulation of tumor progression. Circ_0000144 serves as a novel oncogenic circRNA, and miR-217 is reported to inhibit the malignant phenotypes of cancer cells by targeting AKT3 in TC. The present study aimed to explore the regulatory mechanism of circ_0000144 and miR-217 in the progression of TC.

Methods: Circ_0000144 expression in 32 pairs of TC tissues and different TC cell lines (including BCPAP, K1, H7H83, and TPC-1) was detected by employing a quantitative real-time polymerase chain reaction (qRT-PCR). Circ_0000144 small interfering RNA was used to establish loss-of-function models. Cell counting kit-8 (CCK-8), BrdU (5-bromo-2'-deoxyuridine) and transwell assays were utilized to verify the effects of circ_0000144 on TC cell proliferation, migration and invasion, respectively. Bioinformatics, western blotting, a luciferase reporter experiment and qRT-PCR were employed to confirm the relationships among circ_0000144, miR-217 and AKT3.

Results: Circ_0000144 expression was remarkably elevated in TC tissues (p < 0.001) and TC cell lines. The elevation of circ_0000144 expression was markedly linked to tumor size (p = 0.015), TNM stage (p = 0.025) and lymph node metastasis (p = 0.017) of the patients. Functional studies showed that knocking down circ_0000144 repressed the malignancy of TC cells. Furthermore, miR-217 was identified as a downstream target of circ_0000144; inhibition of miR-217 could reverse the effects induced by circ_0000144 knockdown. Moreover, circ_0000144 could regulate AKT3 expression by suppressing miR-217 expression.

Conclusions: Circ_0000144 exerts a cancer-promoting effect on TC cells via the miR-217/AKT3 pathway.