Fig. 1

Identification of the circRNA circCUL2 in CAFs. A The cluster heat maps show the upregulated circRNAs in CAFs compared with NFs. circRNAs with fold change >2 and p < 0.05 were selected as significantly different. B qRT–PCR analysis of circCUL2 in 20 pairs of CAFs and matched NFs. C Schematic illustration showing the genomic location and splicing mode of circCUL2. The back-splice junction (red arrow) of circCUL2 was confirmed by sanger sequencing. D cDNA and gDNA of NFs and CAFs were amplified with convergent and divergent primers. GAPDH was as the negative control. E qRT–PCR analysis of circCUL2 and linear CUL2 in NFs and CAFs treated with RNase R. F qRT–PCR analysis of circCUL2 and linear CUL2 in NFs and CAFs treated with actinomycin D at the indicated time points. G localization of circCUL2 in pancreatic cancer tissue were detected by RNA FISH. CK19 indicated cancer cell. Scale bar, 50 μm. H The relative expression of circCUL2 in 161 PDAC tissue compared to paired NAT. I-J Association analysis between circCUL2 expression levels and LN status (I) and tumor stages (J). K-L Kaplan-Meier analysis of the correlation between circCUL2 expression levels and OS (K) and DFS (L) of PDAC patients. The median circCUL2 expression was used as the cutoff value. (M) ROC curve analysis of circCUL2 in PDAC tissue and normal tissues. Data are expressed as the mean ± SD of three independent experiments. ^**p < 0.01 and ^***p < 0.001 (two-tailed Student t-tests)