Fig. 1

Identification of gastric cancer progression- and immune evasion-associated circRNAs through microarray. a A circRNA microarray was performed to identify differentially expressed circRNAs in gastric cancer tissues. The circus plot shows the distribution and expression profiles of the detected and differentially expressed circRNAs located on human chromosomes, as well as potential miRNAs interacting with differentially expressed circRNAs (inner, mRNA; median, miRNAs; outer, circRNAs). b The heatmap presents the significantly expressed circRNAs in primary and paired distant metastatic gastric cancer tissues (n = 9). c The heatmap presents the significantly expressed circRNAs in primary gastric cancer tissues responsive (n = 3) or resistant (n = 4) to anti-PD-1 therapy. d Relative expression of circDLG1 in primary and distant metastatic gastric cancer tissues measured by qRT–PCR (n = 30) (P < 0.001). The relative expression of circDLG1 was determined using the relative quantification 2^-ΔΔCT method. Student’s t-test. The data are representative of three technical replicates. e Relative expression of circDLG1 in primary gastric cancer tissues responsive (n = 7) and resistant (n = 23) to anti-PD-1 therapy (P = 0.002). The relative expression of circDLG1 was measured by qRT–PCR and calculated using the relative quantification 2^-ΔΔCT method. Paired Student’s t-test. The data are representative of three technical replicates. f The 30 patients were divided into circDLG1 expression-high (n = 15) and circDLG1 expression-low (n = 15) groups based on the median expression level of circDLG1. Kaplan–Meier analysis was performed to evaluate progression-free survival in the two groups. Patients with high circDLG1 expression presented significantly worse survival than those with low circDLG1 expression (P = 0.02). g ISH analysis of circDLG1 expression (blue staining, positive expression; red staining, negative) and IHC analysis of PD-L1 expression in gastric cancer tissues. Scale bar, 50 μm. h circDLG1 expression in the PD-L1 high and PD-L1 low groups measured by qRT–PCR (P = 0.59). The relative expression of circDLG1 was determined using the relative quantification 2^-ΔΔCT method. Student’s t-test. i The expression of circDLG1 in the TMB high and TMB low groups measured by qRT–PCR (P = 0.60). The relative circDLG1 expression was determined using the relative quantification 2^-ΔΔCT method. Student’s t-test