Metabolic regulation of histone acetylation by ACLY supports MDR1 expression in colorectal cancer and highlights a targetable vulnerability.

Chemoresistance remains a major cause of treatment failure in colorectal cancer (CRC), yet the metabolic mechanisms sustaining efflux-mediated drug resistance are not fully defined. Here, we identify ATP-citrate lyase (ACLY) as a metabolic regulator linking citrate-dependent acetyl-CoA production to epigenetic control of MDR1/ABCB1 expression. Using genetic and pharmacologic approaches, we show that ACLY catalytic activity contributes to the maintenance of histone acetylation at H3K9 and H4K16 and supports MDR1 transcription in CRC cells. Consistently, ACLY overexpression enhances, whereas its inhibition reduces, MDR1 expression and associated resistance-related transcriptional programs. In human CRC specimens, ACLY and MDR1 levels positively correlate, with a stronger association observed in advanced-stage tumors, supporting clinical relevance of this metabolic-epigenetic axis. Metabolic tracing with 13C-glucose suggests that perturbation of citrate flux influences ACLY-associated pathways and acetyl-CoA availability. In this context, vitamin C treatment reduces citrate-derived acetyl-CoA and ACLY phosphorylation and is associated with global histone deacetylation and decreased MDR1 expression in vitro and in KRAS-mutant patient-derived xenografts. Together, these findings highlight ACLY-dependent acetyl-CoA production as a potential metabolic vulnerability linked to epigenetic regulation of drug efflux programs in CRC. Targeting this metabolic-chromatin axis may represent a strategy to modulate MDR1-associated chemoresistance.