Circular RNA circ_0001105 Inhibits Progression and Metastasis of Osteosarcoma by Sponging miR-766 and Activating YTHDF2 Expression.

BACKGROUND: Circular RNAs (circRNAs) play vital roles in the modulation of tumor progression. This study explored the biological functions of circ_0001105 in the progression of osteosarcoma (OS). METHODS: qRT-PCR and in situ hybridization (ISH) were performed to detect the expression status of circ_0001105 in cells and tissues. Bioinformatics analysis, dual-luciferase reporter gene assay, Western blot and qRT-PCR were performed to determine the relationships among RNAs. The CCK-8, colony formation, EdU, transwell and wound healing assays were conducted to evaluate the cell growth, invasion and migration of OS cells. Tumor xenografts were established to investigate the effects of circ_0001105 on tumor growth in vivo. Lastly, the protein expression of YTHDF2 in OS tissues was measured using immunohistochemical staining. RESULTS: Data showed that circ_0001105 and YTHDF2 were significantly lower, while miR-766 was higher in OS tissues compared to adjacent tissues. Low expression of circ_0001105 or YTHDF2 was associated with poor survival of OS patients as demonstrated by the Kaplan-Meier analysis. In addition, miR-766 was identified as a direct binding target of circ_0001105 and YTHDF2. Ectopic overexpression of circ_0001105 or YTHDF2 significantly suppressed OS cell viability and invasion through regulating miR-766. Last, overexpression of circ_0001105 significantly attenuated in vivo tumor growth. CONCLUSION: Our findings suggest that circ_0001105 inhibits OS progression, at least partially, by regulating miR-766/YTHDF2 signaling pathway.