Circ_0071662, a novel tumor biomarker, suppresses bladder cancer cell proliferation and invasion by sponging miR-146b-3p.

Here, we characterized a new circRNA, named circ_0071662, which was downregulated in human bladder cancer tissues and cell lines, compared with matched adjacent normal tissues and normal bladder epithelial cells. Lower circ_0071662 level was observed in patients with advanced bladder cancer and was positively associated with poorer prognosis, including higher degrees of lymph node invasion and distal metastasis, and lower survival rate. Gain- and loss-of-functions showed that circ_0071662 suppressed cell proliferation and invasion in human bladder cell lines T-24 and J82. Bioinformatics analysis revealed that there are six binding sites of miR-146b-3p on circ_0071662 sequence, and pull-down assays demonstrated miR-146b-3p directly bound with circ_0071662. Moreover, circ_0071662 negatively regulated miR-146b-3p expression and positively regulated expression of miR-146b-3p target genes HPGD and NF2. Furthermore, miR-146b-3p could rescue the inhibition of cell proliferation and invasion caused by circ_0071662 overexpression. In conclusion, circ_0071662 suppresses bladder cancer cell proliferation and invasion by sponging miR-146b-3p.