Mcf 10a

Human breast cancer cell lines (SK‐BR‐3, AU565, BT474, MDA‐MB‐361, EFM192A, HCC1954, JIMT1, and ZR‐75‐30) were obtained from the American Type Culture Collection (ATCC) and were all cultured in high‐glucose DMEM (Gibco) supplemented with 10% foetal bovine serum (Gibco), and 100 μg/ml penicillin/streptomycin (Invitrogen). MCF‐10A and MCF‐10CA1a cells were obtained from the Shanghai Cell Bank Type Culture Collection Committee and cultured in DMEM/F12 (Gibco) with 10% horse serum (Gibco), 10 μg/ml insulin (Sigma), 100 μg/ml penicillin/streptomycin (Invitrogen), 0.5 μg/ml hydrocortisone (Sigma), 20 ng/ml EGF (Invitrogen) and 1 ng/ml cholera toxin (Sigma). All cell lines were mycoplasma negative and passed short‐tandem repeat (STR) test verification (Supplementary Data).

The human breast cancer cell lines (MCF‐7, BT474, T47D, ZR‐75‐1, SKBR3, MDA‐MB‐231, and MDA‐MB‐453) and normal endothelial cell line (MCF/10A) were purchased from Cell Bank of Shanghai Institute of Chinese Academy of Sciences. Mouse breast cancer cell line 4T1 was supplied by Nanjing Kebai Biotechnology Co., Ltd. SKBR3 and 4T1 cells were incubated in RPMI‐1640 (Gibco) with 10% FBS (Gibco). MCF/10A cells were maintained with Endothelial Cell medium (Sciencell). The other cells were maintained in DMEM (Gibco) with 10% FBS (Gibco). OSW‐1 was supplied by Changbai Mountain Institute of Traditional Chinese Medicine.¹²

Human breast non‐tumorigenic epithelial cell line MCF‐10A (Shanghai Cell Bank, Type Culture Collection Committee, Chinese Academy of Sciences) was cultured in Dulbecco's modified Eagle medium with 15% foetal bovine serum (FBS). Human breast cancer cell lines MDA‐MB‐231 and MCF‐7 (Shanghai Cell Bank, Type Culture Collection Committee, Chinese Academy of Sciences) were cultured in 1640 medium with 10% FBS and maintained in an incubator with 5% CO₂ at 37°C. For transient small interfering RNA (siRNA) transfection, cells were seeded into normal growth medium at 30% confluence in 6‑well tissue plates 24 hours prior to transfection with 8 nmol/L siRNAs targeting ENC1 (control sense: 5′‐UUC UCC GAA CGU GUC ACG UTT‐3′, antisense: 5′‐ACG UGA CAC GUU CGG AGA ATT‐3′; siRNA1: ENC1 sense: 5′‐CUC UAA AGC AGG UAG AAC AdTdT‐3′, antisense: 5′‐UGU UCU ACC UGC UUU AGA GdTdT‐3′; siRNA2: ENC1 sense: 5′‐CAA UUC CAU CCA CCC AGA AdTdT‐3, antisense: 5′‐UUC UGG GUG GAU GGA AUU GdTdT‐3′) via Lipofectamine 2000 reagent (Invitrogen; Thermo Fisher Scientific, Inc), according to the manufacturer's instructions. All siRNAs and non‑specific siRNA (si‐NC) were constructed by GenePharma (Shanghai GenePharma Co., Ltd.).