TY - JOUR
T1 - 2,3,5-tris(Glutathion-S-yl)hydroquinone (TGHQ)-mediated apoptosis of human promyelocytic leukemia cells is preceded by mitochondrial cytochrome c release in the absence of a decrease in the mitochondrial membrane potential
AU - Yang, Mi Young
AU - Lau, Serrine S.
AU - Monks, Terrence J.
N1 - Funding Information:
This work was supported by National Institute of Environmental Health Sciences grants ES09224 and Southwest Environmental Health Sciences Center grant ES06694. Portions of this work were presented at the American Society for Pharmacology & Experimental Therapeutics meeting in San Diego in April 2003 (Yang, M. Y., Lau, S. S., and Monks, T. J., Changes in the expression and localization of Bcl-2 family proteins during TGHQ-induced apoptosis of HL-60 cells. FASEB J. 17. Abstract #83058) and at the Society of Toxicology Meeting in Baltimore in March 2004 (Yang, M. Y., Lau, S. S., and Monks, T. J., Thioredoxin and TGHQ-induced apoptosis in HL-60 cells. Abstract #1635).
PY - 2005/7
Y1 - 2005/7
N2 - 2,3,5-tris(glutathion-S-yl)hydroquinone (TGHQ), a metabolite of benzene, induces apoptosis in human promyelocytic leukemia (HL-60) cells. However, the mechanisms by which TGHQ induces apoptosis are unclear, and they were the focus of the present investigation. TGHQ stimulated the rapid formation (30 min) of reactive oxygen species (ROS) in HL-60 cells, and co-treatment with catalase or the antioxidant N-acetylcysteine (NAC) completely blocked TGHQ-induced apoptosis, implicating a causative role for ROS in HL-60 cell death. Western blot analysis revealed the complete disappearance of pro-caspase 9 between 1 and 2 hours after exposure of HL-60 cells to TGHQ, concomitant with the appearance of cleaved caspase 9 and increases in caspase 9 activity. The appearance of two cleaved forms of caspase 3 occurred subsequent to increases in caspase 9 activity. Levels of the anti-apoptotic Bcl-2 protein remained constant during TGHQ-induced apoptosis of HL-60 cells, but Bcl-2 S70 phosphorylation decreased. In contrast, changes in the subcellular localization of the pro-apoptotic molecule Bax were observed, with a rapid (15 - 60 min) increase in the ratio of cytosolic to mitochondrial Bax. Cytochrome c release from mitochondria to the cytosol occurred after Bax translocation and the dephosphorylation of pS70 Bcl-2. However the mitochondrial inner transmembrane potential (ΔΨm) was maintained, even after cytochrome c was released from the mitochondria. Cyclosporin A, an inhibitor of the mitochondrial membrane permeability transition pore (PTP), did not completely rescue HL-60 cells from apoptosis. Taken together, we conclude that TGHQ facilitates ROS production, alters the post- translational modification of Bcl-2 and subcellular localization of Bax, culminating in the release of cytochrome c and caspase activation.
AB - 2,3,5-tris(glutathion-S-yl)hydroquinone (TGHQ), a metabolite of benzene, induces apoptosis in human promyelocytic leukemia (HL-60) cells. However, the mechanisms by which TGHQ induces apoptosis are unclear, and they were the focus of the present investigation. TGHQ stimulated the rapid formation (30 min) of reactive oxygen species (ROS) in HL-60 cells, and co-treatment with catalase or the antioxidant N-acetylcysteine (NAC) completely blocked TGHQ-induced apoptosis, implicating a causative role for ROS in HL-60 cell death. Western blot analysis revealed the complete disappearance of pro-caspase 9 between 1 and 2 hours after exposure of HL-60 cells to TGHQ, concomitant with the appearance of cleaved caspase 9 and increases in caspase 9 activity. The appearance of two cleaved forms of caspase 3 occurred subsequent to increases in caspase 9 activity. Levels of the anti-apoptotic Bcl-2 protein remained constant during TGHQ-induced apoptosis of HL-60 cells, but Bcl-2 S70 phosphorylation decreased. In contrast, changes in the subcellular localization of the pro-apoptotic molecule Bax were observed, with a rapid (15 - 60 min) increase in the ratio of cytosolic to mitochondrial Bax. Cytochrome c release from mitochondria to the cytosol occurred after Bax translocation and the dephosphorylation of pS70 Bcl-2. However the mitochondrial inner transmembrane potential (ΔΨm) was maintained, even after cytochrome c was released from the mitochondria. Cyclosporin A, an inhibitor of the mitochondrial membrane permeability transition pore (PTP), did not completely rescue HL-60 cells from apoptosis. Taken together, we conclude that TGHQ facilitates ROS production, alters the post- translational modification of Bcl-2 and subcellular localization of Bax, culminating in the release of cytochrome c and caspase activation.
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U2 - 10.1093/toxsci/kfi165
DO - 10.1093/toxsci/kfi165
M3 - Article
C2 - 15800030
AN - SCOPUS:26944473661
SN - 1096-6080
VL - 86
SP - 92
EP - 100
JO - Toxicological Sciences
JF - Toxicological Sciences
IS - 1
ER -