Hydrogen peroxide induced oxidative stress damage and antioxidant enzyme response in Caco-2 human colon cells

Studies were conducted to evaluate the cell damage caused by exposing human colon carcinoma cells, Caco-2, to hydrogen peroxide at concentrations varying from 0 to 250 mu M for 30 min. Evaluation of cell viability, as measured by trypan blue dye exclusion test, showed that the loss of viability was < 5% at concentrations up to 250 mu M hydrogen peroxide. Cell membrane damage and DNA damage as measured by the leakage of lactate dehydrogenase and the comet assay, respectively, were significantly high at concentrations > 100 mu M hydrogen peroxide compared to those of the control. Antioxidant mechanisms in Caco-2 cells were evaluated by measuring catalase, superoxide dismutase, and glutathione peroxidase activities. Catalase activities remained constant in cells treated with 50250 mu M hydrogen peroxide. Superoxide dismutase activity decreased, whereas glutathione peroxidase activity increased in cells treated with H2O2 concentrations of > 50 mu M. This study showed that with increasing hydrogen peroxide concentration, cell membrane leakage and DNA damage increased, whereas the three antioxidant enzymes responded differently, as shown by mathematical models.