Fig. 1

Elevated levels of circRNA-SORE in sorafenib-resistant HCC. a Four sorafenib-resistant HCC cell lines (HepG2-SR, SKhep1-SR, Huh7-SR and LM3-SR) were established and confirmed using the Real-time Cell Analysis xCELLigence System. Curves demonstrate the growth rate of naïve and sorafenib-resistant cell lines. b qPCR analysis of circRNA-SORE in the four sorafenib-resistant cell lines compared with their parental control cells. c qPCR analysis of circRNA-SORE in LM3-CDX-SR and PDX-SR tumor tissues compared with control tumor tissues. CDX: cell derived xenograft, PDX: patient derived xenograft. d circRNA-SORE information from the UCSC Genome Browser. e Time-course of relative circRNA-SORE and TLE4 expression in HepG2-SR cells treated with actinomycin d (10 μg/mL). f qPCR analysis of circRNA-SORE and TLE4 in HepG2, LM3 and SKhep1 cells with and without RNase R treatment for 30 min at 37 °C. g Verification of the circular nature of circRNA-SORE using divergent and convergent primers. Top, schematic illustration of the circRNA-SORE locus with specific primers. Bottom left, RT-PCR products using divergent primers showing circularization of circRNA-SORE. gDNA, genomic DNA. Bottom right, Sanger sequencing of circRNA-SORE. h Localization of circRNA-SORE (red) in HepG2-SR cells using fluorescence in situ hybridization. Cell nuclei were counterstained with DAPI (blue). Scale bar, 20 μm. Three different independent experiments with three technical repetitions were performed. Data are expressed as the mean ± SEM. Statistical analyses used Student’s t-test, and p < 0.05 was considered statistically significant. * p < 0.05, ** p < 0.01, and *** p < 0.001. NS; not statistically significant