Changes of Mutations and Copy‐Number and Enhanced Cell Migration during Breast Tumorigenesis

Abstract Although cancer stem cells (CSCs) play a major role in tumorigenesis and metastasis, the role of genetic alterations in invasiveness of CSCs is still unclear. Tumor microenvironment signals, such as extracellular matrix (ECM) composition, significantly influence cell behaviors. Unfortunately, these signals are often lost in in vitro cell culture. This study determines putative CSC populations, examines genetic changes during tumorigenesis of human breast epithelial stem cells, and investigates single‐cell migration properties on ECM‐mimetic platforms. Whole exome sequencing data indicate that tumorigenic cells have a higher somatic mutation burden than non‐tumorigenic cells, and that mutations exclusive to tumorigenic cells exhibit higher predictive deleterious scores. Tumorigenic cells exhibit distinct somatic copy number variations (CNVs) including gain of duplications in chromosomes 5 and 8. ECM‐mimetic topography selectively enhances migration speed of tumorigenic cells, but not of non‐tumorigenic cells, and results in a wide distribution of tumorigenic single‐cell migration speeds, suggesting heterogeneity in cellular sensing of contact guidance cues. This study identifies mutations and CNVs acquired during breast tumorigenesis, which can be associated with enhanced migration of breast tumorigenic cells, and demonstrates that a nanotopographically‐defined platform can be applied to recapitulate an ECM structure for investigating cellular migration in the simulated tumor microenvironment.