High glucose increases susceptibility to oxidative-stress-induced apoptosis and DNA damage in K-562 cells.

AIM The study was carried out to evaluate the effect of several substrates on oxidative stress induced apoptosis and in K-562 cells. METHODS Glucose at 5, 11 and 30 mM concentrations was tested, as well as 5 mM glutamine and 5 mM fructose. The cells were exposed to tert-butylhydroperoxide (tBH) and apoptotic cells were evaluated by flow cytometry with FITC-Annexin V and propidium iodide. The effect of glucose concentration on DNA damage was evaluated using hydrogen peroxide and electrophoretic "DNA comets" assay at 5 mM and 30 mM glucose concentrations. RESULTS The exposure of cells to tBH resulted in increased number of apoptotic cells, and this effect was prevented by administration of an antioxidant - N-Acetyl cysteine. Rising concentrations of glucose added to the toxic effect of tBH; we also observed some toxic effect of fructose and no effect of glutamine. We found higher susceptibility to hydrogen peroxide induced DNA damage with 30 mM glucose concentration. CONCLUSION Hyperglycemia increases the cell's susceptibility to oxidative stress and it also amplifies oxidative DNA damage. Glutamine - when used as a sole energetic substrate - showed no protective effect against oxidative stress.