Abstract 7064: BRCA 1/2 haploinsufficiency-associated metabolic dysfunction in benign fallopian tube epithelia

Abstract In 3-17% of women with BRCA1/2 mutations who undergo risk-reducing surgery, pre-neoplastic and neoplastic lesions are found in their fallopian tubes that display differential loss of heterozygosity of BRCA1/2. Precisely how mutations in BRCA1/2 predispose women to develop high grade serous ovarian carcinoma (HGSC) is not completely understood. Although linked to various processes localized in the nucleus, BRCA1/2 may also have essential roles in the cytoplasm, specifically in the regulation of key processes associated with mitochondrial homeostasis and metabolism. Understanding how haploinsufficiency of BRCA1/2 contributes to the potential neoplastic transformation of fallopian tube epithelial cells should reveal new insights into BRCA1/2 function, and ultimately provide novel opportunities for preventative interventions in individuals with this mutation and new treatment opportunities for HGSC associated with BRCA1/2 heterozygosity. We have identified distinct metabolic and mitochondrial deficits in BRCA2 mutation carriers compared to BRCA1 carriers and non-carriers. Fallopian tube epithelial cell lines derived from BRCA2 mutation carriers showed increased levels of mitochondrial respiration and activity followed by BRCA1 mutation carriers and non-carriers. Western blot analysis of mitochondrial proteins regulating glycolysis and oxidative phosphorylation showed differential expression based on mutation status. Transmission electron microscopy of BRCA2 mutation carriers showed increased disrupted mitochondrial networks when compared to wild type, suggesting that mutation status may contribute to increased mitochondrial fission. These observations reveal an entirely new aspect of BRCA1 and BRCA2 biology and further studies will disaggregate the effects of BRCA1 and BRCA2 on mitochondrial function, versus DNA damage repair. Ultimately, this work will provide new insight into the adaptive changes within FT cells which promote neoplastic transformation and inform how high-grade serous carcinoma (HGSC) cells distinctively respond to microenvironmental stimuli. Citation Format: Jovanka Ravix, Iru Paudel, Gauthami Pulivendala, Ramlogan Sowamber, Elizabeth Smith, Matthew Schlumbrecht, David Lombard, Sophia George. BRCA 1/2 haploinsufficiency-associated metabolic dysfunction in benign fallopian tube epithelia abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7064.