Fig. 4

The circMID1 acts as a sponge for miR-506-3p. A HEK293 cells co-transfected with miRNAs mimics or control miRNAs (miR-NC) and luciferase reporter containing circMID1 (circMID1-WT) or mutant construct (circMID1-MUT). Dual luciferase reporter assays were performed. B The predicted binding sites of miR-506-3p and wild type (WT) or mutant (MUT, red) circMID1 are shown. C PC3 and DU145 cells co-transfected with miR-506-3p mimics or control miR-506-3p (miR-NC) and luciferase reporter containing circMID1 (circMID1-WT) or mutant construct (circMID1-MUT). Dual luciferase reporter assays were performed (^**P < 0.01). ^* vs. circMID1-WT + miR-NC. D The Ago2 RIP showed that Ago2 significantly enriched circMID1 and miR-506-3p (^**P < 0.01). E The expression level of miR-506-3p was determined by RT-PCR in PC3 and DU145 cells with si-control or si-circMID1 after MDSC-Exo treatments. ^**, ^##P < 0.01, ^* vs. control, # vs. Exo + si-control. F MS2bp-MS2bs based RIP assay in PC3 cells transfected with MS2bs-circMID1, MS2bs-circMID1mt, or MS2bs-Rluc (G) Relative expression of miR-506-3p in benign prostatic hyperplasia (BPH, n = 31) and PCa tissues (n = 56) determined by qRT-PCR. H Pearson’s correlation analysis showed a positive correlation between miR-506-3p and circMID1 (R = 0.458; P = 0.0004) in PCa tissues. All experiments were performed at least three times