Abstract 4769: Identification of differentially expressed microRNAs in African American women with quadruple-negative breast cancer

Purpose: Recently, we have demonstrated that triple-negative breast tumors (TNBC) that lack the expression of androgen receptor are quadruple-negative tumors (QNBC) and have increased aggressiveness. Additionally, we determined that this is due to a unique gene signature in the QNBC subtype. However, whether this gene signature is associated with a unique miRNA expression and differential in African American (AA) women compared to Caucasian (CA) women has not been determined. Therefore, the purpose of this study is to determine the miRNA expression in presence or absence of androgen receptor in both African American and Caucasian QNBC patients. Methods: miRNA level 3 sequencing files were originally downloaded on June 01 2016 from TCGA for 925 breast cancer patients. The miRNA sequence files (RPKM) and gene expression files (FPKM UQ) were obtained for normal and tumor samples for these patients. Median value of AR FPKM UQ was used as cut-off and divided patient group as AR(+ve/-ve). Log2 fold change values were calculated by comparing AR-negative and AR-positive patients. P-value was calculated using two-tail t-test. GSE19783 (mRNA, miRNA data) was also obtained and was used as validating dataset. Results: Out of 925 patients, 101 patients have TNBC. Among TNBC patients, 107 are QNBC and 8 patients are AR +ve TNBC. Reads per million for 1046 miRNAs were considered for this study.40 miRNAs showed differential expression in QNBC. (p-value and lt 0.05). All BC patients were organized based on race (CA/AA), stage (I/II/III, IV) and subtype (Luminal, Her2type, TNBC).We have found that hsa-mir-452 and hsa-mir-937 expression was high in AR-negative, hsa-mir-190b expression was low in AR -ve African American women. miRNAs expression was changed in QNBC and correlated to AR (hsa-mir-577, hsa-mir-135b and hsa-mir-18a). hsa-mir-375 expression was low in QNBC.hsa-mir-150, hsa-mir-181a-2, hsa-mir-500a, hsa-let-7d, hsa-mir-92a-1, hsa-mir-92a-2, hsa-mir-20a, hsa-mir-17, hsa-mir-30a, hsa-mir-210, hsa-mir-455, hsa-mir-130a are expression was changed in African American women with QNBC. Hsa-mir-3607 is low in African American women, irrespective of AR expression. These results are in process of validation using independent dataset. Discussion/Conclusion: Standard treatment of breast cancer relies on reliable assessment by IHC analysis of ER, PR, and HER2. Our results suggest that the heterogeneity of TNBC is at least partially associated with the presence or absence of AR e