Abstract 4682: Metabolic enzymes as protective modulator of BRCA2 haploinsufficiency and genome instability

Abstract Germline mutations in the BRCA2 tumor suppressor gene predispose individuals to various cancers. Our lab previously discovered that endogenous reactive metabolites selectively degrade BRCA2 below the protective threshold and transiently induced BRCA2 haploinsufficiency. This functional insufficiency promotes genome instability and drives cancer evolution, establishing a direct mechanistic link between metabolic stress and carcinogenesis. My project aims to uncover the cellular mechanisms that counteract metabolic stress and prevent BRCA2 depletion. I hypothesise that specific metabolic enzymes act as protective buffers by detoxifying reactive metabolites and maintaining BRCA2 stability. To investigate this, I employed isogenic cells modeling two distinct classes of BRCA2 mutations - truncating (+/3036del4) and missense (+/D2723H) mutations. These mutations differ in protein expression, subcellular localisation and some of the biochemical properties, making them ideal to examine how different subtypes of BRCA2 mutations influence cellular metabolic requirements.Using a dual-readout targeted metabolic CRISPR-Cas9 knockout screening, I identified metabolic genes essential for cell survival and maintenance of genome stability. The primary screen revealed subtype-specific dependencies, with truncating mutants showing heightened sensitivity to perturbations in energy metabolism, whereas missense mutants relied on DNA damage response-linked metabolic pathways. Focused analysis of the top hits identified distinct metabolic responses associated with energy balance, reactive oxygen species accumulation and ER homeostasis. Ongoing work focuses on mechanistic validation of high-priority candidate genes to elucidate how specific metabolic pathways safeguard BRCA2 function under stress. These findings reveal mutation-specific metabolic vulnerabilities and provide a foundation for identifying potential metabolic interventions to preserved genome stability in BRCA2 mutation carriers. Citation Format: Xiao Zi Huang, Tuan Zea Tan, C. Pawan K. Patro, Li Ren Kong, Ashok R. Venkitaraman. Metabolic enzymes as protective modulator of BRCA2 haploinsufficiency and genome instability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4682.