Abstract Chemotherapy resistance remains a major obstacle in cancer treatment, leading to disease relapse and poor patient outcomes. Although protein acetylation is known to regulate diverse oncogenic processes, its role in therapeutic resistance is incompletely defined. Through an acetylome-based RNA interference screen, we identified mitochondrial dihydrolipoyl transacetylase (DLAT) as a key regulator of chemotherapeutic resistance. We found that DLAT promotes chemoresistance by controlling chemotherapy-induced ROS. Interaction proteomics and mutational analysis revealed that DLAT binds to and acetylates methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) at lysine 44, activating mitochondrial tetrahydrofolate metabolism and increasing 10-formyl-tetrahydrofolate levels. This metabolic rewiring induces expression of the mitochondrial-encoded cytochrome c oxidase II (MT-CO2) and enhances mitochondrial oxidative capacity, thereby supporting survival under chemotherapeutic stress. Analysis of clinical tumor specimens revealed elevated DLAT signaling in patients refractory to chemotherapy or chemoimmunotherapy, supporting the clinical relevance of the finding. Lastly, we developed a decoy peptide, DMp39, that specifically targets DLAT and MTHFD2 signaling, thereby restoring sensitivity to chemotherapy in patient-derived xenograft models and opening a new avenue for therapeutically targeting the crucial pathway involved in chemoresistance. These groundbreaking findings establish DLAT-driven mitochondrial acetylation signaling as a therapeutic vulnerability and provide a new type of therapy that can be combined with standard chemotherapy to benefit patients whose cancers have become resistant to the regimen. Citation Format: Jung Seok Hwang, Jaehyun Kim, Kiyoung Eun, Vanessa Avalos, Sydney Shuff, Margaret Stephens, Sumin Kang. Novel peptide decoy targeting mitochondrial dihydrolipoyl transacetylase-driven redox signaling to improve cancer chemotherapy outcomes abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86 (8Suppl): Abstract nr LB185.
Hwang et al. (Fri,) studied this question.