Fig. 1

circSEPT9 is validated and characterized in TNBC cells. a The cluster heat maps showed the top 15 differentially expressed circRNAs in 4 pairs of human TNBC tissues and adjacent normal tissues. The red and blue strips indicate up-regulated and down-regulated circRNAs, respectively. b Schematic illustration of circSEPT9 formation via the circularization of exons 2 in SEPT9 gene. The back-splice junction sequences and RT-PCR product of circSEPT9 were validated by Sanger sequencing and agarose gel electrophoresis, respectively. c PCR was performed to detect the existence of circSEPT9 and SEPT9 from cDNA and gDNA in TNBC cells using the divergent and convergent primers, respectively. Divergent primers amplified circSEPT9 in cDNA but not genomic DNA (gDNA). d and e PCR and qRT-PCR were conducted to determine the abundances of circSEPT9 and linear SEPT9 mRNA in TNBC cells treated with RNase R at the indicated time points. f The RNA expressions of circSEPT9 and SEPT9 of TNBC cells were analyzed by qRT-PCR after treatment for 12 h and 24 h with actinomycin D. g Nuclear-cytoplasmic fractionation assay indicated that circSEPT9 was mainly localized in the cytoplasm of TNBC cells. GAPDH was considered as a cytoplasmic protein control and U6 was used as a nuclear control. h The localization of circSEPT9 was observed in TNBC tissues (magnification, × 100, Scale bar, 50 μm) and cells (magnification, × 200, Scale bar, 50 μm) by FISH. The nuclei were stained with DAPI. The data are presented as the mean ± SD, **P < 0.01, ***P < 0.001