Fig. 1

circCORO1C is upregulated in LSCC tissues and is associated with poor prognosis. a RNA sequencing of 57 pairs of LSCC and matched adjacent normal mucosal (ANM) tissues to screen differentially expressed circRNAs. Heatmap showing circRNAs expressed in all tissues and those upregulated in LSCC tissues. b Schematic illustration showed the circularization of CORO1C exons 7 and 8 to form circCORO1C. The back-splicing junction of circCORO1C was verified by RT-PCR and Sanger sequencing. c circCORO1C expression levels in human LSCC cell lines (FD-LSC-1, TU-177) and normal cell lines (HOK, HEK293T, MRC-5) were determined by qPCR. d circCORO1C expression in FD-LSC-1 and TU-177 cells verified by RT-PCR. Agarose gel electrophoresis showed that divergent primers amplified circCORO1C in cDNA but not genomic DNA (gDNA). GAPDH served as a negative control. e Validation of circCORO1C stability by RNase R treatment and RT-PCR analysis. f qPCR analysis of the abundance of circCORO1C and linear CORO1C in FD-LSC-1 and TU-177 cells treated with actinomycin D at the indicated times. g Expression levels of circCORO1C in an additional 107 paired LSCC tissues were determined by qPCR. h–j Correlation analysis between circCORO1C expression levels and clinicopathological parameters of LSCC. Expression level of circCORO1C was significantly associated with T stage (h), N stage (i), and clinical stage (j). k Kaplan-Meier analysis of the correlation between circCORO1C expression and overall survival of 96 patients with LSCC. l circCORO1C abundance in nuclear and cytoplasmic fractions of FD-LSC-1 and TU-177 cells was evaluated by qPCR. 18S RNA acted as a positive control of RNA distributed in the cytoplasm, and U6 RNA acted as a positive control of RNA distributed in the nucleus. m Localization of circCORO1C in FD-LSC-1 and TU-177 cells was detected by FISH. Nuclei were stained with DAPI (blue) and circCORO1C probes were labeled with Cy3 (red). The error bars (c, f and l) represent SD of three independent experiments. **P < 0.001