Fig. 4

ECM-induced biomechanical force drives stem cell-like tumor cell quiescence. a MCF-7/4T1 cells were seeded in a flask and 3D Matrigel, following which the cells were harvested for the cell proliferation assay in a 96-well plate (flask and 3D-flask groups). Some of the 3D-cultured MCF-7/4T1 cells were re-seeded in 3D Matrigel and subjected to cell proliferation determination at the same time points (3D group). b Proliferation of MCF-7 cells cultured in a flask, 3D-flask, and 3D gel (3D collagen and fibrinogen culture system). c Cell cycle analysis of MCF-7/4T1/MDA-MB-231 cells cultured in a flask, 3D gels, and 3D-flask. d Immunostaining for Ki67 and CoupTF1 in the flask, 3D gel, and 3D-flask groups. The scale bar is 20 μm. e GO and KEGG enrichment analysis of differentially expressed genes in the 4T1 cells cultured in the flask and 3D culture system, with a significance threshold of p-value < 0.05. f 1 × 10³ 4T1 cells were encapsulated in a 450-Pa 3D Matrigel (or not) and subcutaneously implanted into mice. On days 3 and 5, the mice were treated with PBS or dispase administered via subcutaneous injection. H&E staining of the hypodermis in each group was performed on days 10 and 20 (n = 10). The scale bar was 500 μm. g MCF-7 cells were cultured in the 3D Matrigel for 3 days and isolated for flask culture. After 0, 24, 48, 72, and 96 h of flask culture, cell proliferation or cycle was examined. h MCF-7 cells were seeded in 45-, 90-, and 450-Pa Matrigel for 3 days. Cell cycle and proliferation (in Matrigel) were examined. Three independent experiments were performed. Data are represented as mean ± SEM. P < 0.05, statistical significance