Figure 1. Expression profile of circRNA in TNBC and para-carcinoma tissues by RNA sequencing and characterization of circIFI30. (A) Hierarchical cluster analysis of all target circRNAs in the TNBC and matched para-carcinoma tissues was shown. Each column represents a sample and each row represents a circRNA. Red strip represents high relative expression and green strip represents low relative expression. (B) The cluster heat map showed the top 10 up-regulated and down-regulated circRNAs. (C) The genomic locus of the circIFI30 and the back-spliced junction of circIFI30 were indicated, the back-splice junction sequence was validated by Sanger sequencing. (D) PCR product of circIFI30 was confirmed by agarose gel electrophoresis. (E) CircIFI30, linear IFI30 and GAPDH were amplified from cDNA or gDNA in MDA-MB-231 cells with divergent and convergent primers, respectively. Divergent primers amplified circIFI30 in cDNA but not genomic DNA (gDNA). (F) RNase R treatment was used to evaluate the exonuclease resistance of circIFI30 in MDA-MB-231 cells. GAPDH was measured as a control. (G) Nuclear-cytoplasmic fractionation assay showed that circIFI30 was mainly localized in the cytoplasm of MDA-MB-231 cells. GAPDH was considered as a cytoplasmic control. U6 was used as a nuclear control.