Nicotine switches the form of H2O2-induced cell death from apoptosis to necrosis in U937 cells

Cigarette smoking is a major risk factor for lung diseases and oral disease s. The present study examined the effect of nicotine on H2O2-induced apopto sis in U937 cells. In the presence of 1 mu g/ml nicotine, cell viability wa s not affected, but the cells were unable to undergo H2O2-induced apoptosis and instead died as a result of necrosis. Nicotine reduced the intracellul ar level of ATP, which is an important determinant of the form of cell deat h. These results suggest that nicotine can alter the cell death pathway by reducing the level of intracellular ATP, and that this effect may contribut e to cigarette smoke-induced tissue destruction. (C) 2000 Elsevier Science B.V. All rights reserved.