A lipophilic free radical initiator, 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN) enhances caspase-dependent apoptosis induced by hyperthermia.
OBJECTIVE
A free radical initiator, 2,2'-azobis (2-amidinopropane) dehydrochloride (AAPH), was previously found to enhance apoptosis by hyperthermia. Here, but more lipophilic free radical initiator, 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN) was investigated for its effects as a possible heat sensitizer.


METHODS
Human myelogenous monocytic leukaemia U937 cells were treated with hyperthermia combined with a various concentration of AMVN for investigating its ability to induce apoptosis and various parameters to identify the pathway.


RESULTS
Combined treatment of hyperthermia and AMVN induced DNA fragmentation markedly, while hyperthermia or AMVN alone induced marginal DNA fragmentation. Fractions of cells showed low mitochondrial membrane potential and increased superoxide production after the combined treatment. Experiments using various caspase inhibitors and a fluorogenic monitor of caspase 3 activities indicated that caspase acts both up- and down-stream of mitochondria.


CONCLUSIONS
AMVN is suggested to be a potential heat sensitizer effective at a lower concentration than AAPH. The possible mechanism is discussed.
Li
F-J
FJ
Department of Industrial Hygiene and Occupational Disease, School of Public Health, China Medical University, Shenyang, 110001, China.
Kondo
T
T
Zhao
Q-L
QL
Hayashi
Y
Y
Ogawa
R
R
Cui
Z-G
ZG
Feril
L B
LB
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001391:Azo Compounds / Q000494:pharmacology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000096:biosynthesis / Q000502:physiology*; D004578:Electron Spin Resonance Spectroscopy; D004790:Enzyme Induction; D005609:Free Radicals; D006801:Humans; D006979:Hyperthermia, Induced; D009570:Nitriles / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D020298:U937 Cells
D001391:Azo Compounds; D061945:Caspase Inhibitors; D005609:Free Radicals; D009570:Nitriles; D017382:Reactive Oxygen Species; C055792:2,2'-azobis(2,4-dimethylvaleronitrile); D020169:Caspases