Downregulation of circular RNA hsa_circ_0000144 inhibits bladder cancer progression via stimulating miR-217 and suppressing RUNX2 expression

Abstract Although increasing aberrantly expressed circular RNAs (circRNAs) have been identified among many human cancer tissues, their roles in tumor progression still remain largely unknown. In bladder cancer, the function of hsa_circ_0000144 has not been reported. In our study, we found hsa_circ_0000144 as a novel oncogene in bladder cancer by bioinformatics analysis. We found that hsa_circ_0000144 expression was significantly upregulated in bladder cancer tissues compared with adjacent normal tissues, and its high expression was related with poor prognosis. Additionally, knockdown of hsa_circ_0000144 remarkably suppressed the proliferation and invasion of bladder cancer cells in vitro. Hsa_circ_0000144 silence also led to reduced tumor volumes in vivo. In mechanism, we found that hsa_circ_0000144 was a sponge of miR-217 while miR-217 targeted RUNX2. Our results indicated that the expression of miR-217 was inversely correlated with that of both hsa_circ_0000144 and RUNX2 in bladder cancer tissues. Rescue assays showed that either inhibition of miR-217 or restoration of RUNX2 reversed the suppressive effects of hsa_circ_0000144 knockdown on bladder cancer cell proliferation and invasion. Taken together, these findings demonstrated that hsa_circ_0000144 exerts oncogenic roles in bladder cancer via repressing miR-217 to facilitate RUNX2 expression.