Fig. 5: YK-4-279 relieves FLI1-mediated anti-tumor immunosuppression.

A The FLI1-binding motif was obtained from the Jaspar database to construct a luciferase reporter PGL4 plasmid, specifically expressing a promoter carrying the motif recognized by FLI1. B HK1 and NPC43 cells were transfected with the promoter-luciferase reporter plasmid for 24 h, then treated with YK-4-279 for an additional 48 h, followed by analysis of luciferase activity. C, D HK1 and NPC43 cells were pretreated with either DMSO or YK-4-279 for 24 h, then IFN-γ was added for an additional 24 h. The protein levels of FLI1, CBP, STAT1, p-STAT1 and IDO1 in HK1 and NPC43 cells were measured by western blot (C). Kyn production was determined by ELISA (D). E HK1 and NPC43 cells were pretreated with either DMSO or YK-4-279 for 24 h, then cocultured with activated human T cells for an additional 48 h. CYP1A1 and CYP1B1 mRNA levels in T cells were detected. F–I HK1 and NPC43 cells were pretreated with either DMSO or YK-4-279 for 24 h, then cocultured with activated human CD8⁺ T cells for an additional 48 h. The expression of PD-1 (F) and TIM-3 (G) on CD8⁺ T cells was determined by flow cytometry. The IFN-γ (H) and TNF-α (I) levels in the culture supernatants were measured by ELISA. J HK1 and NPC43 cells were pretreated with either DMSO or YK-4-279 for 24 h, then cocultured with activated human CD4⁺ T cells for an additional 48 h. The proportion of CD25⁺ FoxP3⁺ cells among CD4⁺ T cells was determined by flow cytometry. The results are representative of three independent experiments (B–J). The data are presented as the mean ± SD (B, D–J). Statistical analysis was performed by one-way ANOVA with Tukey multiple comparisons test (B) and two-tailed unpaired t test (D–J). Source data are provided as a Source Data file.