Fig. 4

FLI1 binds to TIE1 promoter and activates TIE1 transcription in NPC cells. A Heatmap showing differential gene expression between CNE1-OE cells and CNE1-VEC cells, 5-8F-shRNA cells and 5-8F-NC cells, as is analyzed by RNA-seq. B–C Correlation analysis between FLI1 and TIE1 in GEO database B and TCGA database C. D–E Western blot C and RT-qPCR D analysis of TIE1 protein and mRNA level in FLI1 overexpression and knockdown NPC cells. F Dual-luciferase reporter assays were used to evaluate TIE1 promoter activity in NPC cells transiently transfected with control vector (VEC), FLI1 overexpression plasmid (FLI1), negative control siRNA (NC) and FLI1-specific siRNA (siFLI1). G–H CNE1 and SUNE1 cells were transiently transfected with vector (VEC) and Flag-FLI1 overexpression plasmid (Flag-FLI1). ChIP-PCR G and ChIP-qPCR H assays of TIE1 promoter region were conducted with Flag or control IgG antibody in CNE1 Flag-FLI1 and SUNE1 Flag-FLI1 cells. I CNE1-VEC and CNE1-FLI1 cells were transiently transfected with siTIE1 or control siRNA. 5-8F-NC and 5-8F-shFLI1 cells were transiently transfected with TIE1 or empty vector plasmids. Cells were seeded at the density of 200, 400, 800 and 1000 cells for 0 Gy, 1 Gy, 2 Gy and 4 Gy IR dose. Colony formation assays and survival fraction curve analysis were employed to assess cell survival at 10–14 days after exposure to indicated IR dose. Data in E, F, H and I are presented as mean ± SD (n = 3). *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001; ns, not significant (Student’s t-test).