Induction of apoptosis without redox catastrophe by thioredoxin-inhibitory compounds.
The dithiol-reducing thioredoxin/thioredoxin reductase system normally maintains the reduced state of key enzymes responsible for the cell's anti-oxidant defences. We therefore addressed the question of whether AW 464--a novel thioredoxin inhibitor--as well as broad spectrum dithiol ligands diamide and phenylarsine oxide are able to induce and execute a regular apoptotic sequence of events without overwhelming the cell's ability to detoxify reactive oxygen species. All three agents were found to target the thioredoxin system in a cell-free assay. In HL-60 leukaemia cells, they were also found to induce Bak activation, cytochrome c release from mitochondria, decreasing Delta Psi m, chromatin condensation, phosphatidyl serine exposure and Tdt-sensitive DNA nicks. At the onset of apoptosis there was no evidence of increases in oxygen free radicals or peroxide in cells treated with AW 464 or diamide. Phenylarsine oxide induced both free radicals and hydrogen peroxide, but this did not appear to interfere with apoptosis. We conclude that pharmacological targeting of thioredoxin can induce a well-orchestrated apoptotic programme.
Pallis
Monica
M
Division of Haematology, Nottingham City Hospital, University of Nottingham, Nottingham NG5 1PB, UK. monica.pallis@nottingham.ac.uk
Bradshaw
Tracey D
TD
Westwell
Andrew D
AD
Grundy
Martin
M
Stevens
Malcolm F G
MF
Russell
Nigel
N
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D001152:Arsenicals / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism; D003958:Diamide / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013879:Thioredoxins / Q000037:antagonists & inhibitors*; D050998:bcl-2 Homologous Antagonist-Killer Protein
D000590:Amino Acid Chloromethyl Ketones; D000975:Antioxidants; D001152:Arsenicals; C494772:BAK1 protein, human; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D013439:Sulfhydryl Reagents; D050998:bcl-2 Homologous Antagonist-Killer Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C029341:oxophenylarsine; D003958:Diamide; D013879:Thioredoxins; D020169:Caspases