Cultivation and Maintenance of Breast Cancer Cell Lines

MCF-7 and ZR-75-1 were purchased from the American Type Culture Collection (ATCC) and were re-authenticated previously [29 (link)]. MCF-7 cells were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM) (Gibco, Grand Island, NY, USA) supplemented with 1% penicillin–streptomycin (Gibco, USA) and 10 % fetal bovine serum (FBS) (Gibco, USA). ZR-75-1 cells were cultured in Improved Minimum Essential Medium (IMEM) (Gibco, USA) supplemented with 1% penicillin–streptomycin and 10% FBS. Epirubicin resistant MCF-7 cells (MCF-7 EpiR) and paclitaxel resistant MCF-7 cells (MCF-7 TaxR) were previously established by our group and were maintained in 10 µM epirubicin and 50 nM paclitaxel, respectively [32 (link)]. Stable BQ-overexpressed ZR-75 and its control ZR-75 EV cell lines were previously generated by our group using lentiviral system [29 (link)]. The cells were cultured in IMEM supplemented with 1% penicillin–streptomycin, 10 % FBS, and 5 µg/mL puromycin (Gibco, USA). The stable BQ-overexpressed MCF-7 cells were generated by transfecting pCDNA3.1-BQ-His (MCF-7 BQ) or pCDNA3.1-Empty (MCF-7 EV), followed by geneticin (Gibco, USA) selection. The stable cell lines were cultured in DMEM supplemented with 1% penicillin–streptomycin, 10 % FBS and 500 µg/mL geneticin.