Abstract
CLU (clusterin) is a tumor suppressor gene that we have previously shown to be negatively modulated by the MYCN proto-oncogene, but the mechanism of repression was unclear. Here, we show that MYCN inhibits the expression of CLU by direct interaction with the non-canonical E box sequence CACGCG in the 5'-flanking region. Binding of MYCN to the CLU gene induces bivalent epigenetic marks and recruitment of repressive proteins such as histone deacetylases and Polycomb members. MYCN physically binds in vitro and in vivo to EZH2, a component of the Polycomb repressive complex 2, required to repress CLU. Notably, EZH2 interacts with the Myc box domain 3, a segment of MYC known to be essential for its transforming effects. The expression of CLU can be restored in MYCN-amplified cells by epigenetic drugs with therapeutic results. Importantly, the anticancer effects of the drugs are ablated if CLU expression is blunted by RNA interference. Our study implies that MYC tumorigenesis can be effectively antagonized by epigenetic drugs that interfere with the recruitment of chromatin modifiers at repressive E boxes of tumor suppressor genes such as CLU.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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5' Flanking Region
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Antineoplastic Agents / pharmacology
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Apoptosis / drug effects
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Base Sequence
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Cell Line, Tumor / drug effects
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Cell Movement
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Cell Proliferation / drug effects
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Chromatin / metabolism
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Clusterin / genetics
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Clusterin / metabolism
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E-Box Elements
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Enhancer of Zeste Homolog 2 Protein
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Epigenesis, Genetic
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Gene Expression Regulation, Neoplastic
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Histone Deacetylase Inhibitors / pharmacology
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Humans
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Hydroxamic Acids / pharmacology
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Molecular Sequence Data
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N-Myc Proto-Oncogene Protein
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Neuroblastoma / drug therapy*
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Nuclear Proteins / metabolism*
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Nuclear Proteins / physiology
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Oncogene Proteins / metabolism*
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Oncogene Proteins / physiology
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Polycomb Repressive Complex 2 / metabolism*
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Promoter Regions, Genetic
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Protein Binding
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Proto-Oncogene Mas
Substances
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Antineoplastic Agents
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CLU protein, human
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Chromatin
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Clusterin
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Histone Deacetylase Inhibitors
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Hydroxamic Acids
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MAS1 protein, human
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MYCN protein, human
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N-Myc Proto-Oncogene Protein
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Nuclear Proteins
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Oncogene Proteins
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Proto-Oncogene Mas
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trichostatin A
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EZH2 protein, human
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Enhancer of Zeste Homolog 2 Protein
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Polycomb Repressive Complex 2