Abstract
Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) is a potential redox agent in cells. The present study investigated changes in cellular redox status [reactive oxygen species (ROS) and glutathione (GSH) levels] and in antioxidant enzymes, in Tempol-treated Calu-6 and A549 lung cancer cells, normal lung WI-38 VA-13 cells, and primary pulmonary fibroblasts. Results demonstrated that Tempol (0.5 ~ 4 mM) either increased or decreased general ROS levels in lung cancer and normal cells at 48 h and specifically increased O2•− levels in these cells. In addition, Tempol differentially altered the expression and activity of superoxide dismutase, catalase, and thioredoxin reductase1 (TrxR1) in A549, Calu-6, and WI-38 VA-13 cells. In particular, Tempol increased TrxR1 protein levels in these cells. Tempol at 1 mM inhibited the growth of lung cancer and normal cells by about 50% at 48 h but also significantly induced cell death, as evidenced by annexin V-positive cells. Furthermore, down-regulation of TrxR1 by siRNA somewhat affected the levels of cell growth inhibition and death as well as ROS in Tempol-treated cells. In addition, Tempol increased the numbers of GSH-depleted cells in both cancer cells and normal cells at 48h. In conclusion, Tempol differentially increased or decreased levels of ROS and various antioxidant enzymes in lung cancer and normal cells, and induced growth inhibition and death in all lung cells along with an increase in O2•− levels and GSH depletion.
Erratum to “Regulatory effects of resveratrol on antioxidant enzymes: a mechanism of growth inhibition and apoptosis induction in cancer cells”
