Fig. 1

circ-SMO is highly expressed in CSCs and GBM. a Gli1 mRNA level in NHA, established GBM cell lines and CSCs. b A total of 12 pairs of GBM and NB samples were subjected to RNA-seq and CIRIquant analysis. Left, differentially expressed circRNAs (p < 0.01 and fold change > 2) with circBase annotation. In total, 1791 circRNAs were upregulated in GBM; 2299 circRNAs were downregulated in GBM. Right, top five highly expressed circRNAs are listed between GBM and NB. c Upper, exons 3–6 of SMO formed circ-SMO. Lower left, PCR products of linear SMO and circ-SMO using convergent or divergent primers. Lower right, Sanger sequencing of circ-SMO junction sequences. d Circ-SMO characters in 3691 CSC. Upper, qPCR of linear or circ-SMO from oligo dT primers and random primers reversely transcripted cDNA. Middle, qPCR of linear SMO or circ-SMO after RNase R treatment. Lower, half-life of linear SMO or circ-SMO. e Left, Northern blotting of circ-SMO and SMO mRNA transcripts by hybridization with exon 4 probes in the absence or presence of RNase R treatment in 456 and 3691 CSCs. Right, junction-specific probe was used to evaluate circ-SMO levels with or without circ-SMO overexpression in indicated cells. Illustration shows the targets of circ-SMO probe, circ-SMO junction shRNAs (referred as sh1 and sh2), and scramble shRNA. f Fluorescence in situ hybridization (FISH) of circ-SMO in 3691 CSC with indicated modifications. Bars, 10 μm. g Cell fraction qPCR in 3691 CSC. β-actin and U6 were used as cytoplasmic or nuclear markers. h Relative expression level of circ-SMO in different cell lines. i Left, relative expression level of circ-SMO in 86 GBM patients and their paired adjacent NB tissues. Right, Survival analysis of 86 GBM patients based on circ-SMO expression. The median score of relative expression levels in tumor tissues based on RT-qPCR was used as the cutoff to define “high” or “low” Circ-SMO expression. MST, median survival time. Lines show the mean ± SD. *p < 0.05, **p < 0.01, ***p < 0.001. In a, c, d, f, g, h, i, Data are representative from at least three experiments with similar results