Clinicopathological features and androgen receptor expression in triple negative breast cancer at Lagos, Nigeria

Beyond Triple-Negative: High Prevalence of Quadruple-Negative Breast Cancer in African Americans

Quadruple-negative breast cancer (QNBC) is a triple-negative breast cancer (TNBC) subtype that lacks expression of the androgen (AR) receptor. Few studies have focused on this highly aggressive breast cancer, portending worse survival rates. We aimed to determine the following: (1) QNBC's molecular and clinical characteristics and compare them with other subtypes and (2) QNBC's association with clinicopathological factors and prognostic markers. We performed immunohistochemical evaluations of ARs on tissue tumor microarrays from FFPE tumor blocks of invasive ductal breast carcinomas in 202 African American women. Univariate analysis was performed using the chi-square test, with survival rates calculated using Kaplan-Meier curves. Overall, 75.8% of TNBCs were AR-negative. Compared to the luminal subtypes, TNBC and QNBC tumors were likely to be a higher grade (p < 0.001); HER2+/AR- and QNBCs were also larger than the other subtypes (p < 0.001). They also expressed increasing mean levels of proteins involved in invasion, such as CD44, fascin, and vimentin, as well as decreasing the expression of proteins involved in mammary differentiation, such as GATA3 and mammaglobin. We found no association between QNBC and stage, recurrence-free survival, or overall survival rates. The high prevalence of TNBC AR-negativity in these women could explain observed worse outcomes, supporting the existence of the unique QNBC subtype.

Kinesin Family Member C1 (KIFC1/HSET) Underlies Aggressive Disease in Androgen Receptor-Low and Basal-Like Triple-Negative Breast Cancers

Quadruple-negative breast cancer (QNBC) lacks traditional actionable targets, including androgen receptor (AR). QNBC disproportionately afflicts and impacts patients of African genetic ancestry. Kinesin family member C1 (KIFC1/HSET), a centrosome clustering protein that prevents cancer cells from undergoing centrosome-amplification-induced apoptosis, has been reported to be upregulated in TNBCs and African-American (AA) TNBCs. Herein, we analyzed KIFC1 RNA levels and their associations with clinical features and outcomes among AR-low and AR-high TNBC tumors in three distinct publicly available gene expression datasets and in the breast cancer gene expression database (bc-GenExMiner). KIFC1 levels were significantly higher in AR-low and basal-like TNBCs than in AR-high and non-basal-like TNBCs, irrespective of the stage, grade, tumor size, and lymph node status. KIFC1 levels were also upregulated in AR-low tumors relative to AR-high tumors among Black and premenopausal women with TNBC. High KIFC1 levels conferred significantly shorter overall survival, disease-free survival, and distant metastasis-free survival among AR-low and basal-like TNBC patients in Kaplan-Meier analyses. In conclusion, KIFC1 levels may be upregulated in AR-low tumors and, specifically, in those of African descent, wherein it may promote poor outcomes. KIFC1 may be an actionable cancer-cell-specific target for the AR-low TNBC subpopulation and could aid in alleviating racial disparities in TNBC outcomes.