Inhibition of cellular respiration by doxorubicin.
Doxorubicin executes apoptosis, a process known to produce leakage of cytochrome c and opening of the mitochondrial permeability transition pores. To define the loss of mitochondrial function by apoptosis, we monitored cellular respiration during continuous exposure to doxorubicin. A phosphorescence analyzer capable of stable measurements over at least 5 h was used to measure [O(2)]. In solutions containing glucose and cells, [O(2)] declined linearly with time, showing that the kinetics of oxygen consumption was zero order. Complete inhibition of oxygen consumption by cyanide indicated that oxidations occurred in the respiratory chain. A decline in the rate of respiration was evident in Jurkat and HL-60 cells exposed to doxorubicin. The decline was abrupt, occurring after about 2 h of incubation. The inhibition was concentration-dependent and was completely blocked by the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone. Respiration in resistant HL-60/MX2 cells, characterized by an altered topoisomerase II activity, was not inhibited by doxorubicin. A decline in cellular ATP was measured in Jurkat cells after 2-4 h of incubation with 20 microM doxorubicin, paralleling the decline in respiration rate. Thus, cells incubated with doxorubicin exhibit caspase-mediated inhibition of oxidative phosphorylation.
Tao
Zhimin
Z
Department of Chemistry, Syracuse University, CST, 1-014, Syracuse, New York 13244-4100, USA.
Withers
Henry G
HG
Penefsky
Harvey S
HS
Goodisman
Jerry
J
Souid
Abdul-Kader
AK
D000255:Adenosine Triphosphate / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects*
D000903:Antibiotics, Antineoplastic; D004317:Doxorubicin; D000255:Adenosine Triphosphate; D004250:DNA Topoisomerases, Type II