Metabolite extraction from cancer cell lines

MCF-7 (human breast adenocarcinoma cell line; CLS—Cell Lines Service, Eppelheim, Germany) and BCC cells [11 (link)] were cultured in Dulbecco’s Modified Eagle Medium: Ham’s F-12 (1:1; DMEM/F-12) (Life technologies, Carlsbad, CA, USA) medium, supplemented with 10% fetal bovine serum (FBS) (Sigma-Aldrich, St. Louis, MO, USA), 100 U/mL penicillin and 100 µg/mL streptomycin (pen-strep) (Sigma-Aldrich, St. Louis, MO, USA). MCF-10A cells (ATCC, Wesel, Germany) were cultured in DMEM/F-12, supplemented with 5% donor equine serum (GE Healthcare Life Sciences, Logan, UT, USA), pen-strep, 10 µg/mL human recombinant insulin (Life Technologies, Carlsbad, CA, USA), 100 ng/mL cholera toxin (Sigma-Aldrich, St. Louis, MO, USA), 20 ng/mL recombinant human epidermal growth factor (Thermo Fisher Scientific, Frederick, MD, USA) and 500 ng/mL hydrocortisone (Sigma-Aldrich, St. Louis, MO, USA). Cells were maintained at 37 °C in a humidified incubator with 5% CO₂. Cells were incubated for 24 h. Metabolite extraction was performed as described earlier by Sellick and co-workers [36 (link)].