Inhibition of apoptosis in acute promyelocytic leukemia cells leads to increases in levels of oxidized protein and LMP2 immunoproteasome
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8012
-
Contributed by Earl R. Stadtman, June 10, 2004
Abstract
On reaching maturity, animal organs cease to increase in size because of inhibition of cell replication activities. It follows that maintenance of optimal organ function depends on the elimination of oxidatively damaged cells and their replacement with new cells. To examine the effects of oxidative stress and apoptosis on the accumulation of oxidized proteins, we exposed acute promyelocytic leukemia cells to arsenic trioxide (As2O3) in the presence and absence of a general caspase inhibitor (benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone), which is known to inhibit caspase-induced apoptosis. We confirm that treatment of cells with As2O3 induces apoptosis and leads to the accumulation of oxidized proteins. Furthermore, inhibition of caspase activities prevented As2O3-induced apoptosis and led to a substantial increase in accumulation of oxidized proteins. Moreover, inhibition of caspase activity in the absence of As2O3 led to elevated levels of the LMP2 immunoproteasome protein. We also show that caspase inhibition leads to increases in the levels of oxidized proteins obtained by treatments with hydrogen peroxide plus ferrous iron. Collectively, these results suggest the possibility that an age-related loss in capacity to carry out apoptosis might contribute to the observed accumulation of oxidized proteins during aging and in age-related diseases.
Footnotes
-
↵ * To whom correspondence should be addressed at: Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 50, Room 2140, 50 South Drive, MSC-8012, Bethesda, MD 20892-8012. E-mail: erstadtman{at}nih.gov.
-
Abbreviations: Ac-DEVD-AMC, Ac-Asp-Glu-Val-Asp-7-amino-4-methylcoumarin; APL, acute promyelocytic leukemia; As2O3, arsenic trioxide; DNPH, 2,4-dinitrophenyl hydrazine; PARP, poly(ADP-ribose) polymerase; ROS, reactive oxygen species; TUNEL, terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling; z-VAD-fmk, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone.
