Certified fetal bovine serum

Human immortalized keratinocyte HaCaT cells were purchased from commercial sources (ICell Bioscience Inc, Shanghai), which were cultured in low glucose Dulbecco’s Modified Eagle Medium (DMEM, Gibco, USA) supplemented with 10% certified fetal bovine serum (Biological Industries, Israel), 100 μg/ml of streptomycin and 100 U/ml of penicillin (Gibco, USA). Cells were incubated at 37 °C with 5% CO₂ in a humidified atmosphere. The biocompatibility of hydrogels was evaluated by Calcein-AM/PI staining (Beyotime Biotechnology, China) and methyl thiazolyl tetrazolium (MTT) assay (Beyotime Biotechnology, China). In vitro stretch experiments were carried out using a custom-made stretching device. HaCaT cells were first seeded on a polydimethylsiloxane (PDMS, DOWSIL, USA) film for 24 h before stretching. Then the culture medium was replaced with hydrogel extract (1 ml hydrogel soaking in 10 ml serum-free medium for 24 h). After culturing for 12 h, cells were then stretched at different strain levels. After stretching, the conditioned medium was obtained for ELISA tests, and cells were fixed using 4% paraformaldehyde for immunofluorescence staining. E-cadherin deficiency is calculated as shown below: $E-cadherindeficiency=\frac{NumberofE-cadherinuncoloredjunctions}{Totalnumberofintercellularjunctions}\times 100\%$

For the study, we used human breast cancer MDA-MB-231 cell line (ATCC^® HTB-26^™). Cells were maintained in Dulbecco’s modified Eagle media (DMEM- high glucose, 01-052-1A, Biological Industries, Beit HaEmek, Israel) with 5% Certified Fetal Bovine Serum (04-001-1A, Biological Industries, Beit HaEmek, Israel) and 4mM glutamic acid at 37 °C in the atmosphere of air containing 5% CO₂.

Human CRC cell lines (including SW480, HCT116, RKO) were purchased from the Cell Bank of Type Culture Collection (CBTCC, China Academy of Sciences, Shanghai, China). And all cells were maintained with Dulbecco’s modified Eagle’s medium (DMEM) (Gibco) supplemented with 10% certified fetal bovine serum (Biological Industries) in the thermal incubator at 37 °C and 5% CO2.