Metabolites are essential substrates for epigenetic modifications. Although nuclear acetyl-coenzyme A (CoA) constitutes a small fraction of the whole-cell pool, it regulates cell fate by locally providing histone acetylation substrate. Here, we report a nucleus-specific acetyl-CoA regulatory mechanism that can be modulated to achieve therapeutic cancer cell reprogramming. Combining phenotypic chemical screen, genome-wide CRISPR screen, and proteomics, we identified that the nucleus-localized pyruvate dehydrogenase complex (nPDC) is constitutively inhibited by the nuclear protein ELMSAN1 through direct interaction. Pharmacologic inhibition of the ELMSAN1-nPDC interaction derepressed nPDC activity, enhancing nuclear acetyl-CoA generation and reprogramming cancer cells to a postmitotic state with diminished cell-of-origin signatures. Reprogramming was synergistically enhanced by histone deacetylase 1/2 inhibition, resulting in inhibited tumor growth, durably suppressed tumor-initiating ability, and improved survival in multiple cancer types in vivo, including therapy-resistant sarcoma patient-derived xenografts and carcinoma cell line xenografts. Our findings highlight the potential of targeting ELMSAN1-nPDC as an epigenetic cancer therapy. Copyright © 2025 Elsevier Inc. All rights reserved.