Abstract P1-06-05: The impact of ethnicity on normal breast biology

Abstract

Abstract The incidence of/mortality from the most aggressive triple negative breast cancer (TNBC) is higher in African American- (AA) than Caucasian (CA)-women. In contrast, breast cancer in Hispanic-women is generally less aggressive. There is an ongoing debate as to whether AA-women have an increased incidence of TNBCs that have poor outcome or there are unique biological factors in AA-women that promote aggressive biology. Through unique approaches, we provide evidence for distinct biology in the normal breasts of CA-women, AA-women, and Hispanic-women. Using resources from the Komen Normal Tissue Bank and a primary cell culturing system that enabled propagation of normal epithelial cells of different lineages including mature-luminal, luminal-progenitor, and stem cells from different ethnic groups, we have identified a subpopulation of CD44high/CD24- cells that are unique to AA-women (p=0.0001). This AA-women-specific subpopulation expressed higher levels of Collagen 3A1, Collagen 5A2, CTNNB1 (β-Catenin of Wnt), FOXC2, and ZEB1 compared to common CD44+/CD24+ subpopulation in every breast. Gene expression pattern in the AA-specific CD44high/CD24- population showed marked similarity to gene expression pattern in the recently described PROCR+ multi-potent mammary stem cells. Indeed, the breast epithelial cells of AA-women were enriched for PROCR-positive stem cells compared to CA-women or Hispanic-women (p=0.015). In contrast to cells from CA- and AA-women, cells isolated from the healthy breast of Hispanic-women displayed mostly differentiated features as they were enriched for CD49f-/EpCAM+ and CD271-/EpCAM+ mature cells. Cells from CA-women, AA-women and Hispanic-women are currently being immortalized to determine the cell types that are preferentially immortalized in each of these ethnic groups. These results suggest ethnicity-dependent differences in Wnt, extracellular matrix, and epithelial to mesenchymal transition (EMT) signaling in normal breast epithelial cells and differences in the proportion of cells that are susceptible to immortalization/transformation. This work is supported by Susan G. Komen for the Cure to HN (SAC110025). Citation Format: Nakshatri H, Anjanappa M, Bhat-Nakshatri P. The impact of ethnicity on normal breast biology. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-06-05.