Abstract 2993: Loss of p53 sensitizes cancer cells to oxidative phosphorylation agonism

Abstract Large scale efforts using CRISPR based gene loss-of-function screens have produced comprehensive catalogs of gene essentiality in hundreds of well annotated cancer models. The equivalent catalogs have not been generated for gene gain-of-function. While loss-of-function (LOF) mutations in TP53 are frequent in cancer, targeting these mutations pharmaceutically remains challenging. To explore synthetic lethalities with p53 LOF we performed genome-wide CRISPR activation screens in wildtype and TP53 knockout isogenic cancer cell lines. We discovered a cluster of genes associated with oxidative phosphorylation (OxPhos) whose overexpression were synthetic lethal with p53 loss. This is consistent with the literature describing a metabolic switch from OxPhos to glycolysis after p53 mutation/loss. Our screen results suggest that this metabolic switch could be a protective action for cancer cells with mutant p53 if OxPhos activation is synthetic lethal with functional p53 deficiency. Indeed we found that overexpression of two of the top OxPhos gene hits from the screen, namely ADCK3 and SCO2, were synthetic lethal with p53 loss in vitro. Moreover, overexpression of ADCK3 resulted in significant growth inhibition of tumors with p53 loss in vivo. Mechanistically, overexpression of either ADCK3 or SCO2 significantly induced cellular ROS production and mitochondrial DNA damage in cancer cells with p53 loss. Our results suggest a model that wildtype p53 is important for maintaining the homeostasis between OxPhos and glycolysis. In the absence of p53 cells cannot tolerate the ROS generated by OxPhos and they switch to glycolytic metabolism. Our results are consistent with the model that hyperactivation of ADCK3, a critical component for electron transport chain, results in an increase in OxPhos and subsequently ROS which in the context of p53 deficient cells is lethal. Similar to p53 deficient cells, cancer cells with hotspot TP53 mutations have been reported to undergo a similar OxPhos to glycolysis metabolic shift and are deficient in the repair of mitochondrial DNA damage caused by OxPhos generated ROS. Our results support that an ADCK3 agonist therapeutic could be an effective strategy to target mutant p53 cancers. Citation Format: Jianhuang Lin, Dimitra Georgopoulou, Shuzhen Wu, Svaty Sachania, Rebecca Saunders, Biju Mangatt, Geeta Sharma, Euan Stronach, Anthony Mazurek, Fiona M. Behan, Benjamin Schwartz, Brendan A. Veeneman. Loss of p53 sensitizes cancer cells to oxidative phosphorylation agonism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2993.