Circ_LDLR promotes the progression of papillary thyroid carcinoma by regulating miR‐1294/HMGB3 axis

Abstract Circular RNAs (circRNAs) have been found to be associated with the development and progression of cancers including papillary thyroid carcinoma (PTC). Circ_LDLR has been reported to be highly expressed in PTC, but its underlying mechanism of action has not been fully elucidated. This study aimed to investigate the role of circ_LDLR in PTC. The expression of circ_LDLR, miR‐1294 and high mobility group box (HMGB) 3 was detected by quantitative real‐time polymerase chain reaction (qRT‐PCR). CCK‐8 assay and transwell assays were employed to value cell viability, invasion and migration abilities. Western blot assay was to detect HMGB3 protein expression. Luciferase reporter gene and pull down assay were used to validate the interaction between miR‐1294 and HMGB3 or circ_LDLR. Circ_LDLR showed high expression levels in PTC tissues and cells and knockdown of it inhibited the growth, invasion, and migration of PTC cells. In addition, miR‐1294 was considered as a downstream target of circ_LDLR, and inhibition of miR‐1294 partially reversed the inhibitory effects of circ_LDLR knockdown on PTC cells growth, invasion, and migration. More importantly, HMGB3 was identified as a downstream target of miR‐1294. Our findings suggest circ_LDLR may plays a promoting role in PTC by downregulating miR‐1294 and upregulating HMGB3 expression. Therefore, circ_LDLR may serve as a valuable prognostic biomarker and therapeutic target for PTC.