Super-enhancer Activates Master Transcription Factor NR3C1 Expression and Promotes 5-FU Resistance in Gastric Cancer.

Poor response to 5-fluorouracil (5-FU) remains an obstacle in the treatment of gastric cancer (GC). Super enhancers (SEs) are crucial for determining tumor cell survival under drug pressure. SE landscapes related to 5-FU-resistance are mapped to GC using chromatin immunoprecipitation-sequencing (ChIP-Seq). SiRNA transcription factors (TFs) screen determines master TF Nuclear Receptor Subfamily 3 Group C Member 1 (NR3C1) activated by SE. High NR3C1 expression driven by SE correlated with 5-FU resistance in patient-derived organoids (PDOs). Phase separation formed by NR3C1 is observed using fluorescence recovery after photobleaching (FRAP). NR3C1 protein and Mediator promoted SE-related gene transcription via phase separation. SEs and NR3C1 co-binding patterns are explored using Cleavage Under Targets and Tagmentation (CUT&Tag) sequencing. 5-FU-related genes driven by NR3C1 are identified using epigenetic reader inhibitor JQ1 and NR3C1 specific inhibitor Cort108297. NR3C1 knockdown increases 5-FU sensitivity and alters the SE landscape through enhancer reprogramming, reducing downstream 5-FU-related target genes. JQ1 and Cort108297 both improve 5-FU efficacy in PDOs and patient-derived xenografts (PDXs) by destroying SEs or inhibiting NR3C1. In conclusion, SE-driven NR3C1 promotes 5-FU resistance in GC. SE destruction and NR3C1 inhibition lead to enhancer reconstruction and reduce 5-FU-related gene transcription, providing alternative therapeutic strategies for improving 5-FU sensitivity.