Abstract
Molecular therapeutics is a recognized promising approach for melanoma, but relevant target genes remain elusive. We report that overload of the recently cloned H11/HspB8 induces apoptosis in 55% of examined melanoma cultures. Apoptosis was determined by activation of caspases-9 and -3 and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL), and was not seen in normal melanocytes. It was associated with H11/HspB8 complexation with transforming growth factor-beta-activated kinase (TAK) 1 and activation of TAK1 and p38 mitogen activated protein 3 kinases. TAK1 was not bound, nor activated by the H11/HspB8 mutant W51C, which has dominant antiapoptotic activity. beta-Catenin was phosphorylated by activated TAK1, inhibiting its nuclear accumulation and mictophthalmia-associated transcription factor and cyclin dependent kinase 2 expression. The dominant-negative TAK1 mutant K63W inhibited beta-catenin phosphorylation and caspase activation. The data indicate that H11/HspB8 overload causes melanoma growth arrest and apoptosis through TAK1 activation and suggest that H11/HspB8 is a promising molecular therapy target.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Apoptosis / drug effects
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Apoptosis / physiology*
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Caspases / drug effects
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Caspases / metabolism
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Cell Nucleus / metabolism
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Cyclin-Dependent Kinase 2 / drug effects
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Cyclin-Dependent Kinase 2 / metabolism
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Doxorubicin / pharmacology
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Enzyme Activation
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Heat-Shock Proteins / genetics
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Heat-Shock Proteins / metabolism*
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Humans
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MAP Kinase Kinase Kinases / metabolism*
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Melanocytes / metabolism
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Melanocytes / pathology
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Melanoma / genetics
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Melanoma / pathology*
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Microphthalmia-Associated Transcription Factor / drug effects
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Microphthalmia-Associated Transcription Factor / metabolism
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Molecular Chaperones
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Phosphorylation
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Tumor Cells, Cultured
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beta Catenin / drug effects
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beta Catenin / metabolism
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p38 Mitogen-Activated Protein Kinases / metabolism
Substances
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HSPB8 protein, human
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Heat-Shock Proteins
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MITF protein, human
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Microphthalmia-Associated Transcription Factor
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Molecular Chaperones
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beta Catenin
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Doxorubicin
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Protein Serine-Threonine Kinases
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CDK2 protein, human
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Cyclin-Dependent Kinase 2
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p38 Mitogen-Activated Protein Kinases
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MAP Kinase Kinase Kinases
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MAP kinase kinase kinase 7
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Caspases