The late increase in intracellular free radical oxygen species during apoptosis is associated with cytochrome c release, caspase activation, and mitochondrial dysfunction.
Mitochondria play central roles in cellular metabolism and apoptosis and are a major source of reactive oxygen species (ROS). We investigated the role of ROS and mitochondria in radiation-induced apoptosis in multiple myeloma cells. Two distinct levels of ROS were generated following irradiation: a small increase observed early, and a pronounced late increase, associated with depletion of reduced glutathione (GSH) and collapse of mitochondrial membrane potential (deltapsi(m)). Exogenous ROS and caspase-3 induced deltapsi(m) drop and cytochrome c release from mitochondria, which could be prevented by molecular (dominant-negative caspase-9) and pharmacologic (zVAD-fmk) caspase inhibitors and overexpression of Bcl-2. Exogenous ROS also induced mitochondrial permeability transition (PT) pore opening and cytochrome c release in isolated mitochondria, which could be blocked by inhibition of PT with cyclosporin A. These results indicate that the late ROS production is associated with increased PT pore opening and decreased deltapsi(m), and GSH, events associated with caspase activation and cytochrome c release.
Chen
Q
Q
Department of Cancer Biology, Cleveland Clinic Foundation, OH 44195, USA.
Chai
Y-C
YC
Mazumder
S
S
Jiang
C
C
Macklis
R M
RM
Chisolm
G M
GM
Almasan
A
A
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death; D045744:Cell Line, Tumor; D002474:Cell-Free System; D002851:Chromatography, High Pressure Liquid; D045304:Cytochromes c / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D005799:Genes, Dominant; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism*; D009101:Multiple Myeloma / Q000378:metabolism; D018384:Oxidative Stress; D017382:Reactive Oxygen Species; D013347:Subcellular Fractions; D013997:Time Factors
D000590:Amino Acid Chloromethyl Ketones; D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D045304:Cytochromes c; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D005978:Glutathione