Hct116

The HeLa human cervical cancer cell line and HCT116 colorectal cancer cell line (The American Type Culture Collection, Manassas, VA, USA) were maintained in Dulbecco’s Modified Eagle’s Medium (DMEM) (for HeLa) or Roswell Park Memorial Institute (RPMI) 1640 medium (for HCT116) containing 10% fetal bovine serum, supplemented with 4 mM of L-glutamine and 50 µg/mL of penicillin/streptomycin (all from HyClone Laboratories, Logan, UT, USA). The cells were cultured in an incubator with 5% CO₂ at 37 °C. The isogenic cell lines expressing control or ATM kinase shRNA were maintained in DMEM supplemented with 1 µg/mL puromycin. The simian virus 40-transformed human fibroblast cell lines, GM0637 and GM9607 (The NIGMS Human Mutant Cell Repository, Camden, NJ, USA) were maintained in RPMI1640 medium supplemented with 10% fetal bovine serum and 50 µg/mL of penicillin/streptomycin.

The HCT 116, HT-29, and KM12 cell lines were purchased directly from the National Institutes of Health, National Cancer Institute (NCI, Frederick, MD, USA); the SW480, SW403, SNU-C1, and SNU-C5 cell lines were purchased from the Korean Cell Line Bank (KCLB, Seoul, Korea); and the DLD-1 and HT-55 cell lines were purchased from American Type Culture Collection (ATCC, Manassas, VA, USA) and Sigma-Aldrich (St. Louis, MO, USA), respectively. DLD-1, HCT 116, HT-29, KM12, SW403, and SW480 cells were maintained in RPMI 1640 medium (HyClone Laboratories, Logan, UT, USA) containing 10% fetal bovine serum (FBS; HyClone Laboratories) and 1% penicillin/streptomycin (PS; Thermo Fisher Scientific, Waltham, MA, USA). HT-55 cells were maintained in MEM (HyClone Laboratories) containing 10% FBS (HyClone Laboratories) and 1% PS (Thermo Fisher Scientific). SNU-C1 and SNU-C5 cells were maintained in RPMI 1640 medium containing 25 mM HEPES (HyClone Laboratories), 10% FBS (HyClone Laboratories), and 1% PS (Thermo Fisher Scientific). All cell lines were maintained under a humidified atmosphere of 5% CO₂ and 95% air at 37 °C. The culture media were refreshed every 2 to 3 days.

Human cancer cell lines used in this study (KB, H226B, A549, LNCaP, DU145, SK-BR-3, MCF7, DLD-1, HCT116, A172, and HepG2) were purchased from American Type Culture Collection (Manassas, VA, USA). The multidrug-resistant cell line KBV20C was derived from KB^{21 (link),22 (link)}. KB, KBV20C, H226B, A549, LNCaP, DU145, and DLD-1 cells were grown in RPMI-1640 (HyClone Laboratories, Logan, UT, USA), while SK-BR-3, MCF7, HCT116, A172, and HepG2 cells were grown in DMEM (HyClone Laboratories), both supplemented with 10% FBS (HyClone Laboratories) and 100 units/mL of penicillin/streptomycin (HyClone Laboratories). KBV20C cells were maintained with 20 nM vincristine in their cell growth medium. Glioblastoma multiform, U87 cells, a kind gift from Dr. Hyunggee Kim (Korea University), were cultured in DMEM/F12 medium (Invitrogen, Waltham, MA). All cells were maintained at 37 °C under 5% CO₂ in a humidified cell culture incubator.

HCT116 human colon adenocarcinoma cells were purchased from the American Type Culture Collection (Manassas, VA, USA). HCT116 was maintained in DMEM supplemented with 10% heat-inactivated fetal bovine serum (FBS; HyClone Laboratories Inc., Logan, UT, USA) and antibiotics (100 µg/mL streptomycin and 100 U/mL penicillin) at 37 °C with 5% CO₂.

HCT116 (CCL-247™) and HT29 (HTB-38™) human colorectal and HepG2 (HB-8065™) human hepatocellular carcinoma cell lines were obtained from the American Type Culture Collection (ATCC, Manassas, VA, USA). The HCT116 and HT29 cells were maintained in McCoy’s 5A medium +2.2 g/L Sodium Bicarbonate (HyClone Laboratories, Logan, UT, USA). HepG2 cells were maintained in Eagle’s minimum essential medium (EMEM). Both cell culture media were supplemented with 2 mM L-Glutamine (Lonza, Walkersville, MD, USA), 10% fetal calf serum (FCS) (HyClone Laboratories, Logan, UT, USA) and Penicillin/Streptomycin; 100 μg/ml each (Gibco, Grand Island, NY, USA). All cells were kept in a humidified atmosphere at 5% CO2 and 37°C.

Colorectal cancer cells HCT116, HT29, RKO were routinely cultured in DMEM culture medium supplemented with 10% FCS (HyClone Laboratories) and gentamicin (Sandoz). Experiments in hypoxia (1% O₂) were done in a humidified anaerobic workstation (Ruskinn Technologies) with 5% CO₂, 10% H₂ and 84% N₂ at 37 °C. All cell lines were purchased from ATCC and regularly tested for Mycoplasma contamination. Cells were treated with beta-blocker propranolol dissolved in DMSO in the final concentration 50 µM. Control cells were cultivated in the presence of an appropriate volume of DMSO. At the end of each experiment, pH of the culture medium was immediately measured by pH meter Seven2Go, S2, Mettler Toledo and microelectrode InLab Nano (Switzerland). The pH values were subsequently normalized to total protein concentration of each sample.