Mcf 7 cells

The human breast cancer MCF-7 cells were obtained from the American Type Culture Collection (Rockville, MD, USA). Cell culture conditions (MCF-7 cells: adherent) and methods were based on previously described procedures [5 (link),6 (link),7 (link),26 (link)]. In brief, MCF-7 cells were routinely cultured in phenol red-containing minimum essential medium α (MEMα) (FUJIFILM Wako Pure Chemical Corporation), supplemented with 10 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), 5% fetal bovine serum (FBS), 100 U/mL of penicillin, and 100 µg/mL of streptomycin in a humidified incubator maintained at 37 °C and 5% CO₂.

MCF7 cells (ATCC) were cultured in RPMI 1640 (Sigma) supplemented with 10% fetal bovine serum (FBS). For LTED, MCF7 cells were grown in phenol red-free RPMI 1640 (Wako) containing 4% dextran-coated charcoal-stripped FBS for 2–4 months. For LTED-RES, LTED cells were treated with 50 or 100 μM resveratrol (Sigma Aldrich, R5010) for 24 h. For ICI 782,780 treatment, cells were cultured with 100 nM ICI 782,780 (Tocris, 1047) for 48 h. Human mammary epithelial cells64 (link) (Lonza) were cultured in mammary epithelial growth media (Lonza) according to manufacturer's protocol at 37 °C with 5% CO₂. Primary invasive breast carcinoma specimens were obtained by surgical excision from patients at the Department of Breast and Endocrine Surgery, Kumamoto University Hospital (Kumamoto, Japan).Informed written consent was obtained from all the patients before surgery. The study protocol was approved by the Ethics Committee of Kumamoto University Graduate School of Medicine (Kumamoto, Japan).