2-methoxyestradiol induces caspase-independent, mitochondria-centered apoptosis in DS-sarcoma cells.
The anti-cancer potential of the natural estrogen metabolite 2-methoxyestradiol is associated with microtubuli interaction, anti-angiogenetic effects and inhibition of superoxide dismutase leading to apoptosis. The effectors of apoptotic signaling through 2-methoxyestradiol, however, are cell type-dependent. We investigated the effect of 2-methoxyestradiol on several events associated with apoptosis in rat DS-sarcoma cells. Translocation of the pro-apoptotic protein Bax to mitochondria was identified as an initial apoptotic event that was accompanied by a decrease in mitochondrial transmembrane potential and the formation of reactive oxygen species (ROS) followed by mitochondrial release of apoptosis inducing factor and endonuclease G. In addition, 2-methoxyestradiol treatment caused upregulation of death receptor ligands FasL and TNFalpha and induced caspase-8 activation. The pan caspase inhibitor Z-VAD-FMK did not suppress apoptotic cell death, however, indicating that the major pro-apoptotic effect of 2-methoxyestradiol is mediated by a caspase-independent mechanism. Furthermore, ROS do not seem to play a pivotal role in the toxic/apoptotic effect of 2-methoxyestradiol in DS-sarcoma cells because supplementation with various antioxidants provided only limit protection. Colony formation was not affected by antioxidants. Therefore, in DS-sarcoma cells, the breakdown of mitochondrial integrity with the subsequent release of mitochondrial nucleases is the main factor in 2-methoxyestradiol mediated cell death.
Lambert
Christine
C
Department of Biological Chemistry and Nutrition, University of Hohenheim, Stuttgart, Germany.
Apel
Katrin
K
Biesalski
Hans Konrad
HK
Frank
Juergen
J
D000077584:2-Methoxyestradiol; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051033:Apoptosis Inducing Factor; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005420:Flavoproteins / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D012513:Sarcoma, Experimental / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D051028:bcl-2-Associated X Protein; D019014:fas Receptor / Q000378:metabolism
C494831:Aifm1 protein, rat; D000590:Amino Acid Chloromethyl Ketones; D000970:Antineoplastic Agents; D000975:Antioxidants; D051033:Apoptosis Inducing Factor; C494828:Bax protein, rat; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D005420:Flavoproteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D051028:bcl-2-Associated X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D004958:Estradiol; D000077584:2-Methoxyestradiol; D004706:Endodeoxyribonucleases; C052391:endonuclease G; D020169:Caspases