Glucocorticoid receptor and RUNX transcription factors cooperatively drive CD8 T cell dysfunction in human cancer.

Glucocorticoids are potent immune regulators, yet how cortisol controls human CD8 T cell function remains poorly defined. Here, we show that cortisol reshapes the transcriptional landscape of human CD8 T cells through cooperation between the glucocorticoid receptor (GR) and RUNX transcription factors. Integrative RNA sequencing (RNA-seq) and chromatin immunoprecipitation followed by sequencing (ChIP-seq) analyses identified genome-wide cortisol-responsive immunoregulatory genes, and NR3C1 deletion confirmed GR dependency. GR chromatin occupancy was enriched at RUNX motifs rather than canonical glucocorticoid response elements, and co-immunoprecipitation confirmed a ligand-dependent interaction between GR and RUNX3, requiring the N-terminal activation function-1 (AF1) domain of GR and the C-terminal region of RUNX3. Single-cell transcriptomic analyses across multiple solid tumors revealed consistent enrichment of GR-RUNX co-regulated genes in tumor-infiltrating CD8 T cells, predominantly within the predysfunctional state. These findings identify RUNX3 as a critical non-canonical GR partner and uncover a therapeutically actionable mechanism by which endogenous glucocorticoids drive CD8 T cell dysfunction in human cancer.