Fig. 1

FGFR3 is overexpressed in BCa tissues, and hsa_circ_0068871 is produced at the FGFR3 gene locus containing exons 4–8. a The relative expression of FGFR3 in normal, low-grade, and high-grade tumour tissues (***p < 0.001) in GSE40355. b Relative expression of FGFR3 in tumour tissues compared with adjacent normal tissues (n = 32, *p < 0.05). c Venn diagram illustrating the overlap of circRNAs detected in the circBase, CircNet and CircInteractome. d Heat maps of expression fold-change in six circRNAs. Red indicates a higher fold-change and blue indicates a lower fold-change. e Expression of six circRNAs in cancer tissues and adjacent normal tissues (n = 10, **p < 0.01). f Hsa_circ_0068871 is produced at the FGFR3 gene locus containing exon 4–8, and the red splicing junction was verified by Sanger sequencing. g RT-PCR assay with divergent or convergent primers indicating the existence of hsa_circ_0068871 in the EJ cell line. h and i, RT-PCR analysis of hsa_circ_0068871, linear FGFR3 and β-actin in EJ and UMUC3 cells treated with RNase R