Abstract
We investigated the in vitro growth inhibitory and apoptotic effects of clinically achievable concentrations of As(2)O(3) (0.5 to 2.0 micromol/L) against human myeloid leukemia cells known to be resistant to a number of apoptotic stimuli. These included chronic myelocytic leukemia (CML) blast crisis K562 and HL-60/Bcr-Abl cells, which contain p210 and p185 Bcr-Abl, respectively, and HL-60 cell types that overexpress Bcl-2 (HL-60/Bcl-2), Bcl-x(L) (HL-60/Bcl-x(L)), MDR (HL-60/VCR), or MRP (HL-60/AR) protein. The growth-inhibitory IC(50) values for As(2)O(3) treatment for 7 days against all these cell types ranged from 0.8 to 1.5 micromol/L. Exposure to 2 micromol/L As(2)O(3) for 7 days induced apoptosis of all cell types, including HL-60/Bcr-Abl and K562 cells. This was associated with the cytosolic accumulation of cyt c and preapoptotic mitochondrial events, such as the loss of inner membrane potential (DeltaPsim) and the increase in reactive oxygen species (ROS). Treatment with As(2)O(3) (2 micromol/L) generated the activities of caspases, which produced the cleavage of the BH3 domain containing proapoptotic Bid protein and poly (ADP-ribose) polymerase. Significantly, As(2)O(3)-induced apoptosis of HL-60/Bcr-Abl and K562 cells was associated with a decline in Bcr-Abl protein levels, without any significant alterations in the levels of Bcl-x(L), Bax, Apaf-1, Fas, and FasL. Although As(2)O(3 )treatment caused a marked increase in the expression of the myeloid differentiation marker CD11b, it did not affect Hb levels in HL-60/Bcr-Abl, K562, or HL-60/neo cells. However, in these cells, As(2)O(3 )potently induced hyper-acetylation of the histones H3 and H4. These findings characterize As(2)O(3) as a growth inhibiting and apoptosis-inducing agent against a variety of myeloid leukemia cells resistant to multiple apoptotic stimuli.
MeSH terms
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ATP Binding Cassette Transporter, Subfamily B, Member 1 / biosynthesis
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ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
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ATP-Binding Cassette Transporters / biosynthesis
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ATP-Binding Cassette Transporters / genetics
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Acetylation / drug effects
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Antineoplastic Agents / pharmacology*
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Apoptosis / drug effects*
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Apoptotic Protease-Activating Factor 1
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Arsenic Trioxide
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Arsenicals / pharmacology*
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Caspases / metabolism
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Cytochrome c Group / metabolism
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Cytosol / metabolism
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Drug Resistance, Multiple
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Drug Resistance, Neoplasm
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Fas Ligand Protein
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Fusion Proteins, bcr-abl / biosynthesis*
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Fusion Proteins, bcr-abl / genetics
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Gene Expression Regulation, Leukemic*
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Genes, bcl-2
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HL-60 Cells / drug effects*
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Histones / metabolism
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Humans
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Immunophenotyping
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K562 Cells / drug effects*
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / genetics
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / pathology*
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Macrophage-1 Antigen / biosynthesis
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Macrophage-1 Antigen / genetics
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Membrane Glycoproteins / biosynthesis
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Membrane Glycoproteins / genetics
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Mitochondria / metabolism
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Multidrug Resistance-Associated Proteins
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Neoplasm Proteins / biosynthesis*
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Neoplasm Proteins / genetics
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Oxides / pharmacology*
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Protein Biosynthesis
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Protein Processing, Post-Translational / drug effects
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Proteins / genetics
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Proto-Oncogene Proteins / biosynthesis
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins c-bcl-2 / biosynthesis
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Proto-Oncogene Proteins c-bcl-2 / genetics*
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bcl-2-Associated X Protein
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bcl-X Protein
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fas Receptor / biosynthesis
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fas Receptor / genetics
Substances
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APAF1 protein, human
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ATP Binding Cassette Transporter, Subfamily B, Member 1
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ATP-Binding Cassette Transporters
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Antineoplastic Agents
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Apoptotic Protease-Activating Factor 1
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Arsenicals
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BAX protein, human
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BCL2L1 protein, human
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Cytochrome c Group
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FASLG protein, human
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Fas Ligand Protein
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Histones
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Macrophage-1 Antigen
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Membrane Glycoproteins
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Multidrug Resistance-Associated Proteins
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Neoplasm Proteins
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Oxides
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Proteins
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-bcl-2
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bcl-2-Associated X Protein
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bcl-X Protein
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fas Receptor
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Fusion Proteins, bcr-abl
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Caspases
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Arsenic Trioxide