A549 human lung cancer cells

MSTO-211H cells were purchased from the American Type Culture Collection (ATCC), Manassas, VA, USA, and A549 human lung cancer cells were obtained from the Korean Cell Line Bank (KCLB), Seoul, Korea. These cell lines were grown in RPMI 1640 containing 100 units/mL penicillin, 0.1 mg/mL streptomycin, and 10% FBS. All cell lines used in the study were authenticated by the ATCC and KCLB using STR-PCR analysis. The cells were incubated in a humidified atmosphere of 5% CO₂ in air at 37°C and maintained in log phase growth. Cell viability was determined by spectrophotometrically measuring the mitochondrial conversion of MTT to formazan. After cells were treated with the specified drugs, MTT was added to the cell suspension for 4 h. After three washes with phosphate-buffered saline (PBS; pH 7.4), the insoluble formazan product was dissolved in dimethyl sulfoxide (DMSO). The optical density (OD) of each well was measured using a microplate reader (Titertek Multiskan; Flow Laboratories, North Ryde, New South Wales, Australia) at 590 nm. The OD resulting from formazan production in control cells was considered as 100% cell viability. All other measurements were expressed as a percentage of the control cell value.