Abstract C038: BRCA2 haploinsufficiency driven neoplastic events in the fallopian tube epithelia

Abstract

Abstract One in 70 women will develop ovarian cancer over their lifetime in the US and epithelial ovarian cancer (EOC) remains the deadliest gynecological cancer. EOC is a heterogenous disease and high-grade serous carcinoma (HGSOC) is the most common histotype. It is genetically unstable due to pathogenic variants in BRCA1, BRCA2, PALB2, ATM, and RAD51 genes involved in DNA damage response and repair which are part of the hereditary breast and ovarian cancer syndrome (HBOC). In women with a BRCA1 or BRCA2 mutation undergoing risk-reducing surgery, 3-17% have pre-neoplastic and neoplastic lesions in their fallopian tubes. These lesions, known as serous tubal intra-epithelial carcinoma (STIC), display differential loss of heterozygosity of BRCA1/2. New insights into BRCA2 function could provide novel opportunities for preventative interventions in individuals with this mutation, and perhaps new treatment opportunities for HGSC associated with BRCA2 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. 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 BRCA2 biology and further studies will disaggregate the effects of 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, Ramlogan Sowamber, Gauthami Pulivendala, David Lombard, Sophia George. BRCA2 haploinsufficiency driven neoplastic events in the fallopian tube epithelia [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C038.