Fig. 4: FLI1 also regulates STAT1 transcription to mediate IDO1 expression.

A Representation of Flag-FLI1 ChIP-seq and input profiles at the STAT1 gene locus in HK1 cells overexpressing Flag-FLI1, treated with or without IFN-γ. B GSEA from the NPC database (GSE102349) suggested that JAK/STAT signaling pathway was less enriched in NPC with a low FIL1 expression (two-tailed unpaired t test). C ChIP-qPCR analysis was conducted with an antibody against Flag and STAT1-promoter-specific primers in HK1 and NPC43 cells overexpressing Flag-FLI1, following IFN-γ treatment for 24 h. D FLI1-KO and WT HK1 and NPC43 cells were transfected with a STAT1 promoter-luciferase reporter PGL4 plasmid for 24 h. Cells were then treated with IFN-γ for another 24 h, followed by analysis of luciferase activity. E STAT1 mRNA level in FLI1-KO and WT HK1 and NPC43 cells, with or without IFN-γ, was determined. F STAT1 and p-STAT1 protein levels in FLI1-KO and WT HK1 and NPC43 cells, with or without IFN-γ, were measured. G The chromatin accessibility at the STAT1 gene locus in FLI1-KO and WT HK1 cells was measured by ATAC-seq, with or without IFN-γ treatment. H, I IDO1 mRNA (H) and protein (I) levels in the indicated NPC cells, with or without IFN-γ treatment, were determined. J Kyn level in the culture supernatants of the indicated NPC cells was detected, with or without IFN-γ treatment. The results are representative of three independent experiments (C–F, H–J). The data are presented as the mean ± SD (C–E, H, J). Statistical analysis was performed by two-tailed unpaired t test (C) and one-way ANOVA with Tukey multiple comparisons test (D, E, H, J). Source data are provided as a Source Data file.