Abstract IA011: mTOR pathway gene expression in association with race and clinicopathological characteristics in Black and White breast cancer patients

Abstract

Abstract Background Aberrant activation of the mammalian Target of Rapamycin (mTOR) pathway has been linked to obesity and endocrine therapy resistance, factors that may contribute to Black White disparities in breast cancer outcomes. We evaluated associations of race and clinicopathological characteristics with mRNA expression of key mTOR pathway genes in breast tumors. Methods Surgical tumor tissue blocks were collected from 367 newly diagnosed breast cancer patients (190 Black and 177 White). Gene expression of AKT1, EIF4EBP1, MTOR, RPS6KB2, and TSC1 were quantified by NanoString nCounter. Differential gene expression was assessed using linear regression on log2-transformed values. Gene expression and DNA methylation data from TCGA were used for validation and investigation of race-related differences. Results Compared to White women, Black women had relative under-expression of AKT1 (log2 fold-change = - 0.31, 95% CI - 0.44, - 0.18) and RPS6KB2 (log2 fold-change = - 0.11, 95% CI - 0.19, - 0.03). Higher vs. lower tumor grade was associated with relative over-expression of EIF4EBP1 and RPS6KB2, but with lower expression of TSC1. Compared to luminal tumors, triple-negative tumors had relative under-expression of TSC1 (log2 fold-change = - 0.42, 95% CI - 0.22, - 0.01). The results were similar in the TCGA breast cancer dataset. Post-hoc analyses identified differential CpG methylation within the AKT1 and RPS6KB2 locus between Black and White women. Conclusions Over-expression of RPS6KB2 and EIF4EBP1 and under-expression of TSC1 might be indicators of more aggressive breast cancer phenotypes. Differential expression of AKT1 and RPS6KB2 by race warrants further investigation to elucidate their roles in racial disparities of treatment resistance and outcomes between Black and White women with breast cancer. Citation Format: Mmadili N. Ilozumba, Song Yao, Adana A. M. Llanos, Angela R. Omilian, Weizhou Zhang, Susmita Datta, Chi Chen Hong, Warren Davis, Thaer Khoury, Elisa V. Bandera, Michael Higgins, Christine B. Ambrosone, Ting Yuan David Cheng. mTOR pathway gene expression in association with race and clinicopathological characteristics in Black and White breast cancer patients [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr IA011.