Fig. 1: Expression profiles of circRNAs in hypoxia-induced PC cells.

a Hierarchical clustering of 48 significantly differentially expressed circRNAs in MIA PaCa-2 cells under normal and hypoxic conditions. b GO analysis showing that these differentially expressed circRNAs and mRNAs were enriched in the energy metabolic process. c Schematic illustration of the genomic loci of the circRNF13 gene. d circRNF13 was amplified by divergent primers in cDNA rather than in gDNA. GAPDH was used as a linear control. e Sanger sequencing confirmed the back-spliced junction of circRNF13. f qRT–PCR detection of the relative expression of circRNF13 and RNF13 in the presence or absence of RNase R. g Nuclear-cytoplasmic fractionation assay showing the location of circRNF13. h FISH assay confirmed that circRNF13 was mainly located in the cytoplasm (magnification: 400x, scale bar: 50 μm). i Representative ISH images of circRNF13 expression in PC tissues and adjacent normal tissues (scale bar: 200 μm, magnification: top 40x, bottom 200x). j ISH scores of circRNF13 in 90 PC tissues and corresponding normal tissues. k Kaplan–Meier survival analysis was used to evaluate the 5-year OS in the circRNF13 low group and circRNF13 high group. Data represent at least three independent experiments and are presented as the means ± SD. *P < 0.05, **P < 0.01.