Silencing of Circ_0135889 Restrains Proliferation and Tumorigenicity of Human Neuroblastoma Cells

Introduction: Neuroblastoma (NB) is the most common extracranial solid tumor in infants and young children. Circular ribonucleic acid (RNA) hsa_circ_0135889 (circ_0135889; hsa_circ argonaute 2 _001) is highly expressed in multiple Cancer tissues, including NB. However, its role in tumor progression of NB was unclear.

Methods: Real-time quantitative polymerace chain reaction was used to detect RNA expression, and western blotting, or immunohistochemistry was used to measure protein expression. Functional experiments were performed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, 5-Ethynyl-2'- deoxyuridine, Annexin V-fluorescein isothiocyanate/propidium iodide, and transwell assays, as well as xenograft tumor model. The intermolecular interaction was predicted by online databases and confirmed by dual-luciferase reporter assay and RNA pull-down assay.

Results: Circ_0135889 and neuronal differentiation 1 (NEUROD1) were upregulated whilst MicroRNA (miR)-127-5p, was downregulated in NB tumors and immortalized NB cells. Silencing of circ_0135889 could suppress cell proliferation, migration and invasion, but enhance Apoptosis rate of NB cells in vitro. More importantly, circ_0135889 depletion inhibited xenograft tumor growth of NB cells. Circ_0135889 was a Sponge for miR-127-5p, and inhibition of miR-127-5p counteracted the inhibitory impact of circ_0135889 knockdown on the malignant behaviors of NB cells. Moreover, NEUROD1 was a direct target of miR-127-5p, and miR-127-5p exerted the anti-tumor role in NB cells by targeting NEUROD1. Furthermore, circ_0135889 regulated NEUROD1expression by sponging miR-127-5p.

Conclusions: Circ_0135889 promoted the tumorigenicity of NB by regulating miR-127-5p/NEUROD1 axis, which might provide a promising therapeutic target for NB.