Fig. 1

The ECM-induced biomechanical force promoted breast tumor stemness. a Representative images and H&E staining images of MCF-7, 4T1 and MDA-MB-231 cells seeded in a flask system and different 3D gels (collagen, fibrinogen, and Matrigel) for 3 days. The scale bar was 50 μm. b, c MCF-7, 4T1 and MDA-MB-231 cells were cultured in a flask system or 3D gels (collagen, fibrinogen, and Matrigel) for 3 days. In vitro colony formation (b) and in vivo tumor formation assay (n = 10) (c) were performed. d Heatmap of stemness-associated genes (SOX2, c-Myc, Nanog, POU5F1, Notch3, Notch4, Tert, CD133, Wnt2, YAP1, AKT1, and ALDH1) expression in MCF-7 cells cultured in flask and different 3D gels (collagen, fibrinogen, and Matrigel) for 3 days, determined using qPCR. e MCF-7, 4T1 and MDA-MB-231 cells were cultured in a flask system or 3D gels (collagen, fibrinogen, and Matrigel) for 3 days. ALDH1⁺ cell subpopulations were determined by flow cytometry. f MCF-7 cells were seeded in different 3D gels (collagen, fibrinogen, and Matrigel) with different stiffness (0, 30, 45, 90, and 450 Pa) for 3 days. Following this, the in vitro colony formation assay was performed. Representative images of tumor cells during atomic force microscopy analysis are shown. g Viability of MCF-7 cells seeded in a flask or 3D Matrigel (90, 450, and 1050 Pa). Representative image and H&E staining of MCF-7 cells seeded in 3D Matrigel (1050 Pa, 3 days) are shown. The scale bar is 50 μm. Three independent experiments were performed. Data are represented as mean ± SEM. P < 0.05, statistical significance