Abstract LB-163: Biological differences underlying racial disparity in breast cancer

Abstract

Abstract Compared to European American (EA) women, African American (AA) women have higher rates of estrogen receptor negative (ER-) breast cancer, more specifically triple-negative (TN) subtype, and show poorer prognosis and survival. Increasing evidence suggests biological differences may contribute to the observed racial disparity. Studies evaluating racial differences in gene expression in breast tumor tissue have reported inconsistent results. Study of normal breast tissue in healthy women may provide new insight into biological mechanisms for cancer development prospectively before tumor occurrence. However, racial influence on gene expression in normal breast tissue has not been extensively studied. In this study, we evaluated racial differences in gene expression in normal breast tissue obtained from 23 healthy women as well as tumor tissue obtained from 108 breast cancer patients. We analyzed RNA-sequencing data and performed differential expression analysis between AA and EA women. We found that differentially expressed genes in normal breast tissue between AA and EA women were enriched in biological pathways related to amino acid metabolism, immune response and signaling, lipid and protein biosynthesis, and cell proliferation and survival. Many of these biological differences persist in tumor tissue between EA and AA women in a subtype-specific manner. For example, in ER- breast cancer, racial differences in gene expression were enriched in amino acid metabolism, cell proliferation and survival pathways, with particular enrichment in immune response and signaling and lipid metabolism pathways in TN breast cancer. For ER+ breast cancer, we did not find any major biological pathway enrichment. In addition, we identified several microRNAs differentially expressed in normal breast tissue between EA and AA women. They may be involved in racial differences in breast carcinogenesis but their potential downstream effects are yet to be determined. Future studies are needed to validate our findings and understand racial-specific biological mechanisms in breast cancer development. Citation Format: Aditi Shendre, Yunlong Liu, Anna Maria Storniolo, Bryan P. Schneider, Jiali Han, Chunyan He. Biological differences underlying racial disparity in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-163. doi:10.1158/1538-7445.AM2017-LB-163