Abstract
Combined treatment with a proteasome inhibitor and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising strategy for cancer therapy. Proteasome inhibitors induce the expression of death receptor 5 (DR5), a receptor for TRAIL, and sensitize cancer cells to TRAIL-induced apoptosis; however, the molecular mechanism of DR5 up-regulation has not been elucidated. In this study, we report that CCAAT/enhancer-binding protein homologous protein (CHOP) is a regulator of DR5 induction by proteasome inhibitor MG132. MG132 induced DR5 expression at a protein and mRNA level in prostate cancer DU145 cells. Furthermore, MG132 increased DR5 promoter activity. Using a series of deletion mutant plasmids containing DR5 promoters of various sizes, we found that MG132 stimulated the promoter activity via the region of -289 to -253. This region contained a CHOP-binding site. Site-directed mutation of the site abrogated the promoter activity enhanced by MG132. An electrophoretic mobility shift assay showed that CHOP directly bound to the MG132-responsive site on the DR5 promoter. Expression of the CHOP protein was increased with MG132 along with DR5 up-regulation. Furthermore, CHOP small interfering RNA attenuated the DR5 up-regulation due to MG132. These results indicate that the proteasome inhibitor MG132 induces DR5 expression through CHOP up-regulation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Apoptosis / drug effects
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Apoptosis / physiology
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Apoptosis Regulatory Proteins
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CCAAT-Enhancer-Binding Proteins / metabolism
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CCAAT-Enhancer-Binding Proteins / physiology*
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Cell Line, Tumor
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Cysteine Proteinase Inhibitors / pharmacology*
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Humans
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Leupeptins / pharmacology*
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Male
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Membrane Glycoproteins / pharmacology
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Mutagenesis, Site-Directed
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Promoter Regions, Genetic / drug effects
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Prostatic Neoplasms / drug therapy
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Prostatic Neoplasms / metabolism*
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Prostatic Neoplasms / pathology
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Proteasome Inhibitors*
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RNA, Messenger / biosynthesis
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RNA, Messenger / genetics
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Receptors, TNF-Related Apoptosis-Inducing Ligand
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Receptors, Tumor Necrosis Factor / biosynthesis*
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Receptors, Tumor Necrosis Factor / genetics
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TNF-Related Apoptosis-Inducing Ligand
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Transcription Factor CHOP
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Transcription Factors / metabolism
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Transcription Factors / physiology*
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Tumor Necrosis Factor-alpha / pharmacology
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Up-Regulation / drug effects
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Up-Regulation / physiology
Substances
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Apoptosis Regulatory Proteins
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CCAAT-Enhancer-Binding Proteins
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Cysteine Proteinase Inhibitors
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DDIT3 protein, human
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Leupeptins
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Membrane Glycoproteins
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Proteasome Inhibitors
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RNA, Messenger
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Receptors, TNF-Related Apoptosis-Inducing Ligand
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Receptors, Tumor Necrosis Factor
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TNF-Related Apoptosis-Inducing Ligand
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TNFRSF10B protein, human
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TNFSF10 protein, human
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Transcription Factors
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Tumor Necrosis Factor-alpha
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Transcription Factor CHOP
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benzyloxycarbonylleucyl-leucyl-leucine aldehyde