Fig. 6

CircCD44 directly binds to IGF2BP2. A RNA pulldown and LC–MS assay. An RNA pulldown assay was applied in the MDA-MB-231 cell line using junction-specific probes, and the samples were subjected to LC–MS. IGF2BP2 was identified and indicated. B The indicated cells were subjected to an RNA pulldown assay, and IGF2BP2 was detected. C An RIP assay was applied using IGF2BP2 antibody in TNBCs, and the complex was subjected to qRT-PCT assay. The relative RNA level of circCD44 was detected, ***, p < 0.001. D Molecular docking predicting the potential binding motif of circCD44 and IGF2BP2; gray, circCD44; blue, IGF2BP2. E Detailed amino acid interacting residues of IGF2BP2 and circCD44 predicted in (D). F Schematic diagram of WT and the mutant allele. circCD44 Mut was generated by changing interacting residues U to A, A to U, C to G and G to C. An IGF2BP2 mutant was established by replacing the interacting residue with IMKDNKHSDCDRQDT. G MDA-MB-231 cells were transfected with WT/Mut circCD44 and subjected to an RNA pulldown assay. IGF2BP2 was detected with immunoblotting. H Cells transfected with WT/Mut IGF2BP2 were subjected to an RIP assay, and the relative RNA level of circCD44 was measured; ***, p < 0.001. Data are representative of at least 2–3 experiments with similar results