Fig. 1

Identification and characterization of circMAST1 in CCa cells and tissues. A, B The differentially expressed circRNAs in six CCa tissues and three normal cervix tissues were shown as the heatmap matrix and volcano plot. C The genomic loci of the circMAST1 gene. circMAST1 is synthesized at the MAST1 gene locus containing exons 9 to 11. The back-splice junction of circMAST1 was identified by Sanger sequencing. D PCR analysis for circMAST1 in cDNA and genomic DNA (gDNA) in SiHa and HeLa cells. E The qRT-PCR analysis for the expression of circMAST1 and MAST1 mRNA after treatment with RNase R in SiHa cells. F The qRT-PCR analysis of circMAST1 using random primers and oligo dT primers, respectively, in reverse transcription experiments. circMAST1 was notably absent in polyA-enriched samples. G The qRT-PCR analysis for the expression of circMAST1 and MAST1 mRNA after treatment with actinomycin D at the indicated time points in SiHa cells. H, I Cytoplasmic and nuclear mRNA fractionation experiments showing that circMAST1 is localized mainly in the nucleus of SiHa and HeLa cells. GAPDH and circ0043280 were applied as positive controls in the cytoplasm, U6 was used as positive control of nucleus. J RNA fluorescent in situ hybridization for circMAST1 in SiHa and HeLa cells; the junction probe was complementary to the back-splice junction sequence of circMAST1. Nuclei were stained with DAPI. Scale bar, 20 µm. K Expression levels of circMAST1 in CCa tissues in comparison with matched normal tissues were measured using qRT-PCR. L Expression levels of circMAST1 in CCa tissues with or without lymph node metastasis were measured using qRT-PCR. M Kaplan–Meier survival curves showed poor overall survival with low expression levels of circMAST1. Each experiment was performed at least three times independently. **P < 0.01. ***P < 0.001. ****P < 0.0001