Fig. 3

circRNA-SORE sustains sorafenib resistance by acting as an miRNA sponge for miR-103a-2-5p and miR-660-3p. a Predicted miRNA interactions with circRNA-SORE using Arraystar’s miRNA target prediction software based on TargetScan & miRanda. b Map of circRNA-SORE and its predicted miRNAs interactions. c qPCR analysis for predicted miRNAs pulled-down by circRNA-SORE. d CCK-8 assays for HepG2-SR cells transfected with miRNA mimics and controls. e CCK-8 assays for HepG2-SR and SKhep1-SR cells transfected with miR-103a-2-5p, miR-660-3p mimics and controls with or without sorafenib treatment. f The co-localization of circRNA-SORE (red) and miR-103a-2-5p/miR-660-3p (green) was observed by fluorescence in situ hybridization (FISH) in HepG2-SR cells. Cell nuclei were counterstained with DAPI (blue). Scale bar: 5 μm. g Left: qPCR analysis of circRNA-SORE in the pull-down lysates of biotinylated miR-103a-2-5p or miR-660-3p. Right: workflow for the biotinylated miRNA pull-down assays. h Ago2 radioimmunoprecipitation assays for circRNA-SORE in wild-type HCC cells and sorafenib-resistant cells. i–j Dual Renilla and firefly luciferase reporter assays using the linear form of wild-type and mutant circRNA-SORE in HepG2-SR cells transfected with NC or miR-103a-2-5p/miR-660-3p miRNA mimics. 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, *** p < 0.001 and **** p < 0.0001. NS; not statistically significant