Apoptosis in pyrogallol-treated Calu-6 cells is correlated with the changes of intracellular GSH levels rather than ROS levels

We investigated the involvement of glutathione (GSH) and reactive oxygen species (ROS) such as H2O2 and O-2(-center dot) in the deaths of pyrogallol-treated Calu-6 cells. Pyrogallol inhibited the growth of Calu-6 cells with an IC50 of approximately 50 mu M. Levels of intracellular H2O2 were not altered or were decreased in pyrogallol-treated Calu-6 cells at 72 h. However, levels Of O-2(-center dot) were increased. Treatment with pyrogallol also reduced the intracellular GSH content. The activity of SOD was down-regulated, but the activity of catalase was up-regulated by pyrogallol at 72 h. ROS scavengers, including Tempol, Tiron, Trimetazidine, and N-acetylcysteine (NAC), did not reduce the levels of the intraceltular O-2(center dot-). Tempol. showing the recovery of GSH depletion in pyrogallol-treated cells significantly prevented apoptosis, while Tiron prevented the loss of mitochondrial transmembrane potential (Delta Psi(m)). In contrast, treatment with NAC showing an increased effect on O-2(center dot-) levels and depletion of GSH intensified pyrogallol-induced apoptosis. In addition, treatment with SOD and catalase significantly prevented the toss of mitochondrial transmembrane potential (Delta Psi(m)) in pyrogallol-treated Calu-6 cells. However, only catalase showing a decreased effect on O-2(-center dot) levels and depletion of GSH prevented pyrogallol-induced apoptosis. Taken together, apoptosis in pyrogallol-treated Calu-6 cells is correlated with the changes of intracellular GSH levels rather than ROS levels. (C) 2007 Elsevier Ireland Ltd. All rights reserved.