Chromatin accessibility governs the differential response of cancer and T-cells to arginine starvation (ChIP-seq)

Depleting the microenvironment of important nutrients such as arginine is a key strategy for immune evasion by cancer cells. Many tumors overexpress arginase but it is unclear how these cancers, but not T-cells, tolerate arginine depletion. Here, we show that tumor cells synthesize arginine from citrulline by upregulating argininosuccinate synthetase 1 (ASS1). Under arginine starvation, ASS1 transcription is induced by ATF4 and CEBPbeta binding to a previously uncharacterized enhancer within ASS1. T-cells cannot induce ASS1, despite the presence of active ATF4 and CEBPbeta, as the gene is repressed. Arginine starvation drives global chromatin compaction and repressive histone methylation which disrupts ATF4/CEBPbeta binding and target gene transcription. We find that T-cell activation is impaired in arginine-depleted conditions, with significant metabolic perturbation linked to incomplete chromatin remodeling and misregulation of key genes. Our results highlight a T-cell behavior mediated by nutritional stress, exploited by cancer cells to enable pathological immune evasion. Overall design: ChIP-seq (33 samples)