DIFFERENT SUSCEPTIBILITIES TO CELL-DEATH INDUCED BY T-BUTYLHYDROPEROXIDE COULD DEPEND UPON CELL HISTOTYPE-ASSOCIATED GROWTH FEATURES

The effects of the oxidizing agent t-butylhydroperoxide (t-BHP) were investigated on three human cell lines of different origin and growth features (A431 epithelial cells, ADF astrocytoma cells and U937 leukemic cells) using electron microscopy and electron paramagnetic resonance spectroscopy. The results indicate that important biophysical and ultrastructural modifications are induced in the plasma and mitochondrial membranes of these cells and that these changes can ultimately lead to cell death. In addition, the cell cytoskeleton also appears to be a target of hydroperoxide-mediated stress. In particular, all three cell types undergo cytoskeletal alterations leading to surface blebbing, a typical characteristic of cell damage. However, the timing and extent of this damage as well as that occurring at the mitochondrial and plasma membrane levels seems to be different: cells with weak (ADF) or absent (U937) cell-to-cell and cell-substrate contacts and a poorly developed cytoskeleton appear to be more susceptible than other cell types (e.g., A431) to t-BHP-mediated injury. These diverse cell susceptibilities to hydroperoxide-mediated oxidative stress could thus depend upon cell histotype-associated growth featurs.