Induction of type 1 programmed cell death in U937 cells by the antioxidant, butylated hydroxy-toluene or the free radical spin trap, NTBN

Oxidative stress can initiate programmed cell death and contributes to the patho-physiology of a number of diseases. Low micromolar to millimolar conc entrations of various antioxidants or free radical scavengers promote cell growth and reduce cellular suicide induced by several functionally distinct agents, including some known to produce oxidative stress. Severe anoxia or inhibitors of oxidative phosphorylation also initiate programmed cell deat h. These results seem paradoxical. In order to compare the response of U937 monoblastoid cells to higher concentrations of an antioxidant or a free ra dical-spin trap, cells were cultured with 20-80 mu M concentrations of buty lated hydroxy-toluene or with 5 to 60 mM concentrations of the free radical spin trap, N-tertiary butyl phenyl-nitrone. At these concentrations, both agents inhibited cellular proliferation and induced oligosomic DNA, detecte d by its 'laddering' after electrophoresis on agarose, confirmed by TUNEL ( BHT) or flow cytometric (NTBN) evidence of hypodiploid DNA and ultrastructu ral evidence of a type 1 programmed cell death. The ability of hydroxy-tolu enes to oxidize DNA and promote carcinogenesis and whether free radical spi n traps could augment or interfere with the response of malignantly transfo rmed cells to chemotherapy or ionizing radiation provide the raison d'etre of these studies. (C) 1999 Elsevier Science Ltd. All rights reserved.