A novel circular RNA (hsa_circRNA_102336), a plausible biomarker, promotes the tumorigenesis by sponging miR-515-5p in human bladder cancer.

Bladder cancer (BC) ranks as the ninth common human tumor in the world with an increasing incidence. Circular RNAs (circRNAs) have been revealed to exhibit promotive or suppressive impacts on tumor progression of various human cancers, including BC. However, due to the variety of circRNAs, the whole circRNAs network in BC remains unclear. In our study, differentially expressed circRNAs between BC and normal samples in GSE92675 dataset was analyzed by microarray. Circ_102336 was identified to be sharply increased in both BC tissue samples and cell lines, and increased circ_102336 is correlated with a worse overall survival rate of BC patients. Overexpression of circ_102336 dramatically increased the cell proliferation viability of T24 and 5637 cells, while knockdown of circ_102336 exhibited opposite effects. Moreover, circ_102336 knockdown could increase the sensitivity of T24 and 5637 cells to CDDP. In mechanism, circ_102336 was demonstrated to directly bind to and negatively regulate miR-515-5p. Inhibition of miR-515-5p reversed the repressive effects of si-circ_102336 on BC cell proliferation viability. KEGG analysis showed that ATP-binding cassette (ABC) transporters and apoptosis were the major two pathways associated with circ_102336/miR-515-5p axis. therefore, we suggested that circ_102336 indirectly regulate apoptosis and ABC transport pathways through miR-515-5p to finally modulate BC cell proliferation and chemo-resistance.