Mutations in the estrogen receptor alpha hormone binding domain promote stem cell phenotype through notch activation in breast cancer cell lines

• Published in: Cancer letters Vol. 428; pp. 12 - 20
• Main Authors: Gelsomino, L., Panza, S., Giordano, C., Barone, I., Gu, G., Spina, E., Catalano, S., Fuqua, S., Andò, S.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01-08-2018; Elsevier Limited
• Subjects: Biotechnology; Breast cancer; CD44 antigen; Cell activation; Cell self-renewal; Cloning; Endocrine therapy; Epidermal growth factor; ESR1 mutations; Estrogen receptors; Estrogens; Genotype & phenotype; Kinases; Ligands; Metastases; Metastasis; Mortality; mRNA; Mutation; Notch protein; NOTCH signaling pathway; Notch4 protein; Phenotypes; Phosphorylation; Plasmids; Precision medicine; Proteins; Serine; Stem cells; Stemness; Tailored therapy; Tumor cell lines; ESR1 mutations; Stemness; Breast cancer; NOTCH signaling pathway; Tailored therapy
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/j.canlet.2018.04.023

The detection of recurrent mutations affecting the hormone binding domain (HBD) of estrogen receptor alpha (ERα/ESR1) in endocrine therapy-resistant and metastatic breast cancers has prompted interest in functional characterization of these genetic alterations. Here, we explored the role of HBD-ESR1 mutations in influencing the behavior of breast cancer stem cells (BCSCs), using various BC cell lines stably expressing wild-type or mutant (Y537 N, Y537S, D538G) ERα. Compared to WT-ERα clones, mutant cells showed increased CD44+/CD24- ratio, mRNA levels of stemness genes, Mammosphere Forming Efficiency (MFE), Self-Renewal and migratory capabilities. Mutant clones exhibited high expression of NOTCH receptors/ligands/target genes and blockade of NOTCH signaling reduced MFE and migratory potential. Mutant BCSC activity was dependent on ERα phosphorylation at serine 118, since its inhibition decreased MFE and NOTCH4 activation only in mutant cells. Collectively, we demonstrate that the expression of HBD-ESR1 mutations may drive BC cells to acquire stem cell traits through ER/NOTCH4 interplay. We propose the early detection of HBD-ESR1 mutations as a challenge in precision medicine strategy, suggesting the development of tailored-approaches (i.e. NOTCH inhibitors) to prevent disease development and metastatic spread in BC mutant-positive patients.
•ESR1 hormone binding domain mutations increase breast cancer stem cell activity.•NOTCH activation promotes stemness phenotype in mutant-positive breast cancer cells.•ERα S118 phosphorylation sustains NOTCH activation and stemness in mutant clones.•NOTCH-tailored therapy may be suitable in breast cancer mutant-positive patients.