FOXM1 Transcriptionally Co-Upregulates Centrosome Amplification and Clustering Genes and Is a Biomarker for Poor Prognosis in Androgen Receptor-Low Triple-Negative Breast Cancer.

Simple Summary: Quadruple-negative breast cancer (QNBC; ER−, PR−, HER2−, and AR−) is a highly proliferative subtype of breast cancer that has no targeted treatment options. Chemotherapy, which is toxic to both malignant and healthy cells, is the mainstay treatment for this subpopulation. Centrosome amplification and clustering are cancer cell-specific traits that are upregulated in QNBC relative to other subtypes; thus, centrosome declustering drugs have been suggested to be a promising anticancer therapeutic strategy for this subgroup. However, the targeting of new centrosome biogenesis is neglected, rendering these drugs less effective. Herein, we propose targeting FOXM1, a master transcription regulator that drives the synchronous upregulation of centrosome amplification and clustering genes to circumvent this neglect. We discovered an overdrive of a FOXM1-mediated transcriptional signaling cascade in AR-low relative to AR-high triple-negative breast cancers (TNBCs). Hence, we assert that targeting FOXM1 may be a more efficacious anticancer strategy than centrosome declustering alone, suggesting FOXM1 could be a promising biomarker and actionable target in AR-low TNBC. There are currently no approved targeted treatments for quadruple-negative breast cancer [QNBC; ER−/PR−/HER2−/androgen receptor (AR)−], a subtype of triple-negative breast cancer (TNBC). AR-low TNBC is more proliferative and clinically aggressive than AR-high TNBC. Centrosome amplification (CA), a cancer hallmark, is rampant in TNBC, where it induces spindle multipolarity-mediated cell death unless centrosome clustering pathways are co-upregulated to avert these sequelae. We recently showed that genes that confer CA and centrosome clustering are strongly overexpressed in AR-low TNBCs relative to AR-high TNBCs. However, the molecular mechanisms that index centrosome clustering to the levels of CA are undefined. We argue that FOXM1, a cell cycle-regulated oncogene, links the expression of genes that drive CA to the expression of genes that act at kinetochores and along microtubules to facilitate centrosome clustering. We provide compelling evidence that upregulation of the FOXM1-E2F1-ATAD2 oncogene triad in AR-low TNBC is accompanied by CA and the co-upregulation of centrosome clustering proteins such as KIFC1, AURKB, BIRC5, and CDCA8, conferring profound dysregulation of cell cycle controls. Targeting FOXM1 in AR-low TNBC may render cancer cells incapable of clustering their centrosomes and impair their ability to generate excess centrosomes. Hence, our review illuminates FOXM1 as a potential actionable target for AR-low TNBC. [ABSTRACT FROM AUTHOR]