Fig. 1

CircRNA-SORE is overexpressed in sorafenib-resistant HCC cells. a Three sorafenib-resistant HCC cell lines (HepG2-SR, LM3-SR, and SKhep1-SR) were established and confirmed by the Real-time Cell Analysis xCELLigence System (Roche Applied Sciences). Curves demonstrate the inhibitory effect of sorafenib on parental (P) and sorafenib-resistant (SR) cell lines. b Hierarchical clustering of 14 upregulated circRNAs and 14 downregulated circRNAs in HepG2-SR cells compared with parental HepG2 cells by Arraystar Human CircRNA Array analysis. CircRNAs with fold change >2 and p < 0.05 were selected as significantly different. c Scatter plots (left panel) and volcano plots (right panel) of the differentially expressed circRNAs. Red dots indicate differentially expressed circRNAs (p < 0.05 and fold change > 2). d CircRNA_104797 levels (normalized by GAPDH) in parental (P) and resistant (R) cell lines treated with the indicated concentrations of sorafenib (7 μM for HepG2, 6 μM for LM3 and SKhep1) for 72 h. e Diagram illustrating back-splicing of circRNA-SORE from the TLE4 host gene. f Time-course of the relative expression of circRNA-SORE and TLE4 in HepG2-SR cells treated with actinomycin D (10 µg/mL). g qPCR analysis of circRNA-SORE and GAPDH mRNA in HepG2-SR, LM3-SR and SKhep1-SR cells with or without RNase R treatment for 30 min at 37 °C. h Relative expression of circRNA-SORE in mRNA and non-mRNA samples in the indicated cell lines. Three independent experiments with three technical repetitions were performed. Data are expressed as mean ± SEM (error bars). Statistical analyses used Student’s t test. ***p < 0.001. NS not significant