CircHIPK3 Promotes Thyroid Cancer Tumorigenesis and Invasion through the Mirna-338-3p/RAB23 Axis.

Objective：Thyroid cancer is a common type of endocrine malignancy, and its incidence has been steadily increasing in many regions of the world. Numerous studies have found that the circRNAs in various cancer types are aberrantly expressed, which could be potential biological diagnostic markers and therapeutic targets. The purpose of this study was to investigate the role of circHIPK3 in the development and progression of thyroid cancer and its mechanism. Subject and Methods：qRT-PCR was used to detect the relative expression levels of circHIPK3 in thyroid cancer cell lines (K1, CAL-62, TPC1), human thyroid normal cells (Nthy-ori 3-1), 10 pairs of thyroid cancer tissues and corresponding adjacent normal tissues. CCK-8 and Transwell assays were used to detect the proliferation and metastasis ability of cells. The targeted relationships between circHIPK3-miR-338-3p and miR-338-3p-RAB23 were predicted by bioinformatics analysis and verified by dual-luciferase reporter assays. Results and Conclusion: The downregulation of circHIPK3 significantly reduced the migration, invasion and proliferation of thyroid carcinoma. Then, we demonstrated that circHIPK3 up-regulated the expression of its target gene RAB23 by sponging miR-338-3p to promote the tumorigenesis and invasiveness of thyroid cancer. This study is the first to find that circHIPK3 plays the role of oncogenetic circRNA in thyroid cancer, which may provide new insights into how circRNA affects the progression of thyroid cancer. Our study also showed that circHIPK3 could be a novel biomarker for thyroid cancer.