Rabionet, MarcPolonio-Alcalá, EmmaRelat, JoanaYeste, MarcSims-Mourtada, JenniferKloxin, April M.Planas, MartaFeliu, LidiaCiurana, JoaquimPuig, Teresa2023-10-112023-10-112021-09Rabionet, Marc, Emma Polonio-Alcalá, Joana Relat, Marc Yeste, Jennifer Sims-Mourtada, April M. Kloxin, Marta Planas, Lidia Feliu, Joaquim Ciurana, and Teresa Puig. “Fatty Acid Synthase as a Feasible Biomarker for Triple Negative Breast Cancer Stem Cell Subpopulation Cultured on Electrospun Scaffolds.” Materials Today Bio 12 (September 1, 2021): 100155. https://doi.org/10.1016/j.mtbio.2021.100155.2590-0064https://udspace.udel.edu/handle/19716/33532This article was originally published in Materials Today Bio. The version of record is available at: https://doi.org/10.1016/j.mtbio.2021.100155. © 2021 Published by Elsevier Ltd.There is no targeted therapy for triple negative breast cancer (TNBC), which presents an aggressive profile and poor prognosis. Recent studies noticed the feasibility of breast cancer stem cells (BCSCs), a small population responsible for tumor initiation and relapse, to become a novel target for TNBC treatments. However, new cell culture supports need to be standardized since traditional two-dimensional (2D) surfaces do not maintain the stemness state of cells. Hence, three-dimensional (3D) scaffolds represent an alternative to study in vitro cell behavior without inducing cell differentiation. In this work, electrospun polycaprolactone scaffolds were used to enrich BCSC subpopulation of MDA-MB-231 and MDA-MB-468 TNBC cells, confirmed by the upregulation of several stemness markers and the existence of an epithelial-to-mesenchymal transition within 3D culture. Moreover, 3D-cultured cells displayed a shift from MAPK to PI3K/AKT/mTOR signaling pathways, accompanied by an enhanced EGFR and HER2 activation, especially at early cell culture times. Lastly, the fatty acid synthase (FASN), a lipogenic enzyme overexpressed in several carcinomas, was found to be hyperactivated in stemness-enriched samples. Its pharmacological inhibition led to stemness diminishment, overcoming the BCSC expansion achieved in 3D culture. Therefore, FASN may represent a novel target for BCSC niche in TNBC samples. Highlights • Polycaprolactone scaffolds provide a softer 3D alternative to traditional cell culture. • Scaffolds expand the triple negative breast cancer stem cell niche. • Fatty Acid Synthase (FASN) is hyperactivated in scaffold-cultured cells. • FASN inhibition overcomes the stemness expansion achieved in 3D culture. Graphical abstract available at: https://doi.org/10.1016/j.mtbio.2021.100155triple negative breast cancerthree-dimensional cell culturepolycaprolactoneelectrospun scaffoldsbreast cancer stem cellsfatty acid synthasegood health and well-beingArticle