Touré, Savanna

Objectives/Goals: This project will enrich our understanding of basal breast carcinogenesis, highlighting the distinct biological differences in breast cancer risk between non-Hispanic Black (NHB) or non-Hispanic White (NHW) women, but also has the potential to provide real-world solutions thereby contributing to reducing health disparities in breast cancer outcomes Methods/Study Population: In the biological investigation, I am utilizing a unique cohort of normal breast tissues from Mayo Clinic patients who underwent breast reduction surgery that have self-identified as NHB or NHW premenopausal women. From these tissues, we are able to subculture human mammary epithelial cells, which we will use for our consequent experiments. For the qualitative study, I aim to recruit up to 40–50 eligible NHB women identified at increased risk for breast cancer and conduct semi-structured qualitative interviews informed by the National Institute on Minority Health and Health Disparities Research Framework. Results/Anticipated Results: Gene expression profiling on our cohort of 15 NHB and 40 NHW premenopausal women identified a gene expression signature in NHB women indicative of elevated Hedgehog signaling, a key factor in triple-negative breast cancer (TNBC) development and progression. I hypothesize that persistent activation of Hedgehog signaling within NHB women instigates the proliferation and transformation of basal stem cells within the breast, thus fueling TNBC development. Understanding the perceptions and experiences of NHB women that are identified as being at an increased risk for BC will aid in the identification of barriers and facilitators to their risk reduction care and in turn provide implementation strategies that could contribute to alleviating the racial disparity seen in TNBC morbidity, mortality, and preventative care. Discussion/Significance of Impact: The significance of this project lies in its dual approach, uncovering basal breast cancer mechanisms in a high-risk group using normal breast tissue and evaluating the perspectives from NHB women to enhance the practical relevance of our findings.

Abstract Triple negative breast cancer (TNBC) represents an aggressive and therapeutically challenging breast cancer subtype with higher incidence and mortality rates in non-Hispanic Black (NHB) women. This disparity persists even after adjusting for socioeconomic factors, tumor biology, and quality of care. The study aims to unravel specific molecular mechanisms underlying this disparity, with a focus on Hedgehog signaling pathways in premenopausal NHB women. Understanding these mechanisms is vital for developing targeted therapies and personalized medicine approaches to address these health disparities. Our research utilized a unique cohort of NHB and non-Hispanic White (NHW) women who underwent breast reduction surgery at the Mayo Clinic and donated breast tissue samples for our study. We isolated RNA from whole tissue sections from a cohort of 12 NHB and 40 NHW women who were parous and premenopausal at time of surgery. We performed gene expression profiling using NanoString BC360 and IO360 assays. This allowed us to identify a distinct gene expression signature characteristic of basal-like/TNBC and indicative of heightened activity in the Hedgehog signaling pathway. We also employed advanced cell culture techniques to generate tissue organoids and subculture human mammary epithelial cells (HMECs) that preserve the intrinsic characteristics of the original tissue samples. We found that significantly differential expression of IL20RA and SOX10, principal factors in the gene expression signature, were preserved in both the derived organoids and the HMECs. These results suggest a potential intrinsic difference in the activation of the Hedgehog pathway in the breast epithelial cells of NHB women. This activation may contribute to increased proliferation and transformation of basal stem cells within the breast, possibly fueling the development and progression of TNBC. The implication of activated Hedgehog signaling in NHB women opens new avenues for understanding TNBC disparities. IL20RA and SOX10 represent potential biomarkers for TNBC risk that may serve as a stratification tool for NHB women. The results of this study have the potential to improve assessment and management of TNBC risk among NHB women, thereby contributing significantly to reducing health disparities in breast cancer outcomes. Citation Format: Jennifer Vanessa Cabezas, Savanna Touré, Matthew Wilson, Melody L. Stallings Mann, Laura M. Pacheco-Spann, Joshua W. Ogony, Mark E. Sherman, Derek C. Radisky. Identifying molecular mechanisms in triple negative breast cancer disparities: Unveiling the role of Hedgehog signaling in non-Hispanic Black women [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(6_Suppl):Abstract nr 2139.