CircSPIDR acts as a tumour suppressor in cervical adenocarcinoma by sponging miR-431-5p and regulating SORCS1 and CUBN expression

To identify circular RNAs (circRNAs) with tumor suppressor activity against cervical adenocarcinoma, we compared the circRNA levels of cervical adenocarcinoma and normal cervical tissues. We found that circSPIDR was dramatically downregulated in cervical adenocarcinoma tissues. In cervical adenocarcinoma cells, overexpression of circSPIDR reduced cell viability, inhibited colony formation and promoted apoptosis, whereas knockdown of circSPIDR exerted the opposite effects. CircSPIDR overexpression also suppressed the tumorigenicity of cervical adenocarcinoma cells in a xenograft mouse model. CircSPIDR was found to sponge miR-431-5p, thereby de-repressing sortin-related VPS10 domain-containing receptor 1 (SORCS1) and cubilin (CUBN) and inhibiting the development of cervical adenocarcinoma. In clinical cervical samples, circSPIDR expression correlated negatively with miR-431-5p expression and positively with SORCS1 and CUBN expression. These results demonstrated that circSPIDR suppresses cervical adenocarcinoma by competitively binding to miR-431-5p, thus upregulating SORCS1 and CUBN. These findings suggest circSPIDR could serve as a novel therapeutic target for treatment of cervical adenocarcinoma patients.