Gallic acid-induced lung cancer cell death is accompanied by ROS increase and glutathione depletion

Gallic acid (GA) is generally distributed in a variety of plants and foods, and its various biological effects have been reported. Here, we investigated the effects of GA and/or caspase inhibitors on Calu-6 and A549 lung cancer cells in relation to cell death and reactive oxygen species (ROS). The growths of Calu-6 and A549 cells were diminished with an IC50 of approximately 30 and 150 lM GA at 24 h, respectively. GA also inhibited the growth of primary human pulmonary fibroblast (HPF) cells with an IC50 of about 300 lM. GA induced apoptosis and/or necrosis in lung cancer cells, which was accompanied by the loss of mitochondrial membrane potential (MMP, ΔΨ_m). The percents of MMP (ΔΨ_m) loss and death cells by GA were lower in A549 cells than in Calu-6 cells. Caspase inhibitors did not significantly rescued lung cancer cells from GA-induced cell death. GA increased ROS levels including O₂^·- and induced GSH depletion in both lung cancer cells. Z-VAD (pan-caspase inhibitor) did not decrease ROS levels and GSH depleted cell number in GA-treated lung cancer cells. In conclusion, GA inhibited the growth of lung cancer and normal cells. GA-induced lung cancer cell death was accompanied by ROS increase and GSH depletion.