Abstract
Arsenic trioxide (As₂O₃) is a highly effective treatment for patients with refractory/relapsed acute promyelocytic leukemia (APL), but resistance to As₂O₃ has recently been seen. In the present study, we report the findings that 2 of 15 patients with refractory/relapsed APL treated with As₂O₃ were clinically As₂O₃ resistant. Leukemia cells from these 2 patients harbored missense mutations in promyelocytic leukemia gene-retinoic acid receptor-α gene (PML-RARA) transcripts, resulting in amino acid substitutions of A216V and L218P in the PML B2 domain. When wild-type or mutated PML-RARA (PR-WT and PR-B/L-mut, respectively) were overexpressed in HeLa cells, immunoblotting showed SUMOylated and/or oligomerized protein bands in PR-WT but not in PR-B/L-mut after As₂O₃ treatment. Protein-localization analysis indicated that PR-WT in the soluble fraction was transferred to the insoluble fraction after treatment with As₂O₃, but PR-B/L-mut was stably detected in fractions both with and without As₂O₃. Immunofluorescent microscopy analysis showed PR-WT localization as a microgranular pattern in the cytoplasm without As₂O₃ and as a macrogranular pattern with As₂O₃. PR-B/L-mut was diffusely observed in the cytoplasm with and without As₂O₃. Nearly identical localization patterns were observed in patients' primary cells. Therefore, B2 domain mutations may play an important role in aberrant molecular responses toAs₂O₃ and may be critical for As₂O₃ resistance in APL.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adult
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Antineoplastic Agents / pharmacology
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Antineoplastic Agents / therapeutic use
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Arsenic Trioxide
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Arsenicals / pharmacology
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Arsenicals / therapeutic use*
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Binding Sites / genetics
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Cytoplasm / drug effects
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Cytoplasm / metabolism
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Drug Resistance, Neoplasm / genetics
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Female
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HeLa Cells
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Humans
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Immunoblotting
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Leukemia, Promyelocytic, Acute / drug therapy*
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Leukemia, Promyelocytic, Acute / genetics
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Leukemia, Promyelocytic, Acute / pathology
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Male
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Microscopy, Fluorescence
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Middle Aged
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Mutation, Missense*
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Neoplasm Recurrence, Local / genetics
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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Oncogene Proteins, Fusion / genetics*
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Oncogene Proteins, Fusion / metabolism
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Oxides / pharmacology
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Oxides / therapeutic use*
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Promyelocytic Leukemia Protein
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Receptors, Retinoic Acid / genetics
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Receptors, Retinoic Acid / metabolism
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Retinoic Acid Receptor alpha
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Reverse Transcriptase Polymerase Chain Reaction
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Sumoylation / drug effects
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Transcription Factors / genetics
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Transcription Factors / metabolism
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Transcription, Genetic / drug effects
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism
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U937 Cells
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Young Adult
Substances
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Antineoplastic Agents
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Arsenicals
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Nuclear Proteins
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Oncogene Proteins, Fusion
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Oxides
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Promyelocytic Leukemia Protein
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RARA protein, human
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Receptors, Retinoic Acid
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Retinoic Acid Receptor alpha
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Transcription Factors
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Tumor Suppressor Proteins
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promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein
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PML protein, human
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Arsenic Trioxide