Breast Cancer Cell Lines and Conditioned Media

Three types of human breast carcinoma cell line, including MCF7, MDA-MB-231 (M231) and SK-BR-3, were used in this study. Primary human normal fibroblasts (NF) were isolated as described previously and used as a control [28 (link)]. MCF7 and NF were cultured in Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12 (Hyclone, Logan, UT, USA). M231 was cultured in L-15 (Macgene, Beijing, China). SK-BR-3 was cultured in McCoy’s 5A medium (Macgene). All of the cell culture media were supplemented with 10% fetal bovine serum (Hyclone), 100 U/mL penicillin, and 100 U/mL streptomycin. All cells were cultured at 37°C with 5% CO₂ and 95% relative humidity. CM was collected from serum-free medium cultured on each cell line for 48 h, and centrifuged at 2000 rpm for 15 min to delete cell debris for exosome capture. All of the samples were stored at −80°C until use.