Fig 2: N‐Myc binds to DLL1 promoter to activate NOTCH1 signaling pathway in GBM cells. (A) Left schematic diagram shows the top 20 genes positively correlated with MYCN in the TCGA GBM RNA‐seq database. The right schematic diagram shows positively correlated genes (adjusted P < 0.05 and r > 0) of MYCN that were enriched in KEGG pathway analysis using DAVID software. (B) Schematic diagram shows the promoter regions of DLL1 and DLL3 are divided into 9 parts for ChIP assays. (C) ChIP analyses of the N‐Myc‐bound promoter regions of DLL1 and DLL3. The corresponding isotype IgG was used as a negative control. (D) Dual‐luciferase reporter system analyses of luciferase activity in GBM cells co‐transfected with reporter plasmids containing the DLL1/DLL3 promoter sequences and MYCN expression plasmids and qRT‐PCR analyses of the expression of DLL1/DLL3 in GBM cells transfected with MYCN expression plasmids. (E, F) qRT‐PCR and Western blotting analyses of the expression of indicated proteins in HUWE1‐KD cells compared with NC cells. (G) Western blotting analyses of nuclear and cytoplasmic N1ICD in HUWE1‐KD cells. (H) Western blotting analyses of the expression of Hes family BHLH transcription factor 1 (HES1) and HEY1 in HUWE1‐KD cells. (I) Growth curves of HUWE1‐KD cells treated with DAPT (25 μmol/L) tested by CCK‐8 assays. (J, K) Representative images of Transwell migration and invasion assays of HUWE1‐KD cells treated with DAPT (25 μmol/L). Data are presented as mean ± SD. *, P < 0.05; **, P < 0.01; ***, P < 0.001. Abbreviations: KD, knockdown; NC, negative control; TCGA, The Cancer Genome Atlas; ChIP, Chromatin immunoprecipitation; HEY1, Hes Related Family BHLH Transcription Factor With YRPW Motif 1; HES1, Hes Family BHLH Transcription Factor 1; SD, Standard Deviation

Fig 3: miR-130b may regulate DLL1 mRNA stability by directly targeting the 3'UTR in prostate cancer cells. (A) The possible binding site of miR-130b and DLL1 was predicted by TargetScan 7.2. (B) The luciferase activity of the WT of DLL1 was significantly decreased after the transfection with the miR-130b mimic, while there was no significant difference between the non-control and miR-130b mimic groups cloned with MUT DLL1. Data are presented as the mean ± standard deviation. **P<0.01. miR, microRNA; DLL, Delta-like 1; UTR, untranslated region; MUT, mutant; WT, wild type; NC, negative control.

Fig 4: miR-130b downregulates the protein level of p-PI3K, p-AKT, MMP9 and DLL1. miR-130b mimic or DLL1 siRNA significantly decreased the protein level of p-PI3K, p-AKT, MMP9 and DLL1. Data are presented as the mean ± standard deviation. *P<0.05, mimic group vs. NC group. p-AKT, phosphorylated-protein kinase B; MMP9, matrix metalloproteinase-9; miR, microRNA; PI3K, phosphatidylinositol 3 kinase; DLL, Delta-like 1.

Fig 5: DLL1 expression is upregulated in prostate cancer. (A) Western blotting and (B) analysis of DLL1 expression. In prostate cancer cells, DLL1 expression level was significantly increased compared with the control group. Data are presented as the mean ± standard deviation. **P<0.01, tumor group vs. control group. DLL, Delta-like 1.