Resistance to nitric oxide-mediated apoptosis in HL-60 variant cells is associated with increased activities of Cu,Zn-superoxide dismutase and catalase
M. Yabuki et al., Resistance to nitric oxide-mediated apoptosis in HL-60 variant cells is associated with increased activities of Cu,Zn-superoxide dismutase and catalase, FREE RAD B, 26(3-4), 1999, pp. 325-332
Nitric oxide (NO) released from (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)a
mino]diazen-1-ium-1,2-diolate (DETA/NO or NOC-18) induces apoptosis in huma
n leukemia HL-60 cells. In this study, we isolated a HL-60 variant cell lin
e, HL-NR6, that is resistant to DETA/NO toxicity as assessed by DNA fragmen
tation, morphology, and colony forming ability. The variant cells also show
ed resistance to reactive oxygen species (ROS) such as superoxide and hydro
gen peroxide as well as NO donors, but not to anti-tumor drugs. We found th
at HL-NR6 cells when compared with HL-60 cells possessed twice the activiti
es of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) and catalase, but no change in
Mn-SOD nor in glutathione peroxidase. Immunoblotting confirmed the high le
vels of both enzymes in the variant cell. We also observed that ROS generat
ion following DETA/NO exposure was substantially higher in HL-60 cells than
in HL-NR6 cells, using the 2',7'-dichlorofluorescein fluorometric method.
Moreover, the SOD mimetic Mn(III) tetrakis(1-methyl-4-pyridyl) porphyrin an
d exogenous catalase effectively attenuated DETA/NO-elicited DNA fragmentat
ion in HL-60 cells. Taken together, these data suggested that the NO resist
ance in HL-NR6 cells is associated with the increased Cu,Zn-SOD/catalase an
d that NO-mediated apoptosis in HL-60 cells is correlated with the generati
on of ROS and derived molecules like peroxynitrite. (C) 1998 Elsevier Scien
ce Inc.