Abstract
Estrogens are suggested to play a role in the development and progression of proliferative diseases such as breast cancer. Like other steroid hormone receptors, the estrogen receptor-alpha (ERalpha) is a substrate of protein kinases, and phosphorylation has profound effects on its function and activity. Given the importance of DNA-dependent protein kinase (DNA-PK) for DNA repair, cell cycle progression, and survival, we hypothesized that it modulates ERalpha signaling. Here we show that, upon estrogen stimulation, DNA-PK forms a complex with ERalpha in a breast cancer cell line (MELN). DNA-PK phosphorylates ERalpha at Ser-118. Phosphorylation resulted in stabilization of ERalpha protein as inhibition of DNA-PK resulted in its proteasomal degradation. Activation of DNA-PK by double-strand breaks or its inhibition by siRNA technology demonstrated that estrogen-induced ERalpha activation and cell cycle progression is, at least, partially dependent on DNA-PK.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antigens, Nuclear / genetics
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Antigens, Nuclear / metabolism
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Binding Sites
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Breast Neoplasms / genetics
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Breast Neoplasms / metabolism
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Breast Neoplasms / pathology
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COS Cells
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Cell Line, Tumor
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Cell Proliferation / drug effects
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Chlorocebus aethiops
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Chromones / pharmacology
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DNA Breaks, Double-Stranded
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DNA Repair
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DNA-Activated Protein Kinase / antagonists & inhibitors
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DNA-Activated Protein Kinase / genetics
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DNA-Activated Protein Kinase / metabolism*
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DNA-Binding Proteins / antagonists & inhibitors
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Estrogen Receptor alpha / genetics
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Estrogen Receptor alpha / metabolism*
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Estrogens / metabolism
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Estrogens / pharmacology
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Humans
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Immunoblotting
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Immunoprecipitation
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Ku Autoantigen
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Morpholines / pharmacology
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Phosphorylation / drug effects
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Protein Binding / drug effects
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RNA Interference
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Ubiquitin / metabolism
Substances
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2-(morpholin-4-yl)benzo(h)chromen-4-one
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Antigens, Nuclear
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Chromones
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DNA-Binding Proteins
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Estrogen Receptor alpha
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Estrogens
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Morpholines
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Ubiquitin
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DNA-Activated Protein Kinase
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Xrcc6 protein, human
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Ku Autoantigen