Cisplatin-Resistant Colorectal and Cervical Cancer Cell Lines

This study employed the DLD1 human colorectal carcinoma cells, parental human cervical carcinoma cell line KB-3-1 (a sub-line of HeLa), and its cisplatin-resistant sub-line KB-CP.5. KB-CP.5 cells were originally selected in a single step in 0.5 μg cisplatin/mL (1.6 μM) in our laboratory, as described previously (20 (link), 21 (link)). KB lines were originally generated in the laboratory of MMG. DLD-1 cells were provided by the National Cancer Institute (part of the NCI-60 collection). All cell lines were thawed immediately prior to experimentation, and cell lines are characterized by NCI using short tandem repeat profiling. The cisplatin stock solution used for culturing CP.5 cells were prepared in PBS. The cisplatin-resistant cells were maintained in the presence of cisplatin, which was removed from growth medium three days prior to all experiments. All cell lines were grown as monolayer cultures at 37°C in 5% CO₂, using either Dulbecco's modified Eagle medium (DMEM, KB cells), or Roswell Park Memorial Institute medium (RPMI, DLD1 cells) with 4.5 g/L glucose (both from Invitrogen, Carlsbad, CA), supplemented with L-glutamine, penicillin, streptomycin and 10% fetal bovine serum (BioWhittaker, Walkersville, MD). Resistance of CP.5 cells to cisplatin was confirmed on a regular (at least monthly) basis, using cell viability assays as described herein.