Cytotoxicity Evaluation of Human Colon Cancer Cell Lines

For cytotoxicity tests, three different human colon cancer cell lines were used: HCT15 and HCT116 were purchased from the ATCC (American Type Culture Collection). HCT116oxR was established by one of the authors (U. J.) at the Institute of Cancer Research, Department of Medicine I, Medical University Vienna, Austria, as described in ref. 46 (link). Every 3–4 passages, the cells were treated with 10 μM oxaliplatin for 3 days to ensure maintenance of the resistance. All cell culture media and reagents were purchased from Sigma-Aldrich Austria and all cell culture materials such as dishes, plates and flasks from StarLab Germany unless indicated otherwise. Cells were grown as adherent monolayer cultures in 75 cm² culture flasks in RPMI 1640 medium supplemented with 10% heat-inactivated fetal bovine serum (Invitrogen) and 4 mM l-glutamine without antibiotics at 37 °C under a humid atmosphere containing 5% CO₂ and 95% air. The murine colon cancer cell line CT26 and murine leukemia L1210 (both from ATCC) were grown in DMEM/F12 or RMPI 1640 medium, respectively, supplemented with 10% heat-inactivated fetal bovine serum.