Fig. 1

The identification and characterizations of circFOXK2 in HCC. A Heatmap exhibiting FOXK2 gene-derived circRNAs in HCC tissue compared with ANTs detected by qRT-PCR. B The expression of circFOXK2 in human HCC cell lines (Huh7, HepG2, Hep3B, and SK-Hep1) and normal hepatocyte line (LO2) were detected by RT-qPCR. C qRT-PCR was used to confirm the expression of circFOXK2 between 92 pairs of human HCC tissues and their counterpart adjacent normal tissue. D The expression of circFOXK2 was significantly high in 84% of HCC patients. E Kaplan–Meier's analyses of the OS of 92 HCC patients with high and low expression of circFOXK2. F Schematic illustration exhibiting the circularization of three exons, including exon2, exon3 and exon4, forming circFOXK2. G Sanger sequencing was used to demonstrate the back-splicing junction of circFOXK2. The arrow represents the special splicing junction of circFOXK2. H Through PCR analysis, divergent primer detected circular RNAs in cDNA but not in gDNA. I qRT-PCR was conducted to measure the relative level of circFOXK2 and FOXK2 linear RNA treated with or without RNase R. J The relative level of circFOXK2 and FOXK2 linear RNA in different time points was determined by qRT-PCR. K Localization of circFOXK2 in HepG2 and Huh7 cells was visualized by FISH. circFOXK2 probes were tagged with Cy3 (red) and DAPI (blue) was identified as nuclei. Data were represented as means ± SD with at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001