Abstract
We examined the effects of 9-cis retinoic acid (RA) on the expression levels of retinoid X receptor alpha (RXR alpha) and its phosphorylated form (p-RXR alpha) in HL-60 and HL-60R cells. 9-cis RA reduced both RXR alpha and p-RXR alpha in HL-60 cells, but did neither in HL-60R cells. However, when the HL-60R cells were treated with the combination of 9-cis RA plus PD98059, MEK inhibitor, the p-RXR alpha and RXR alpha proteins all markedly decreased. Moreover, the combination of those agents induced apoptosis in HL-60R cells. Phosphorylation of RXR alpha might be associated with RA-resistance in HL-60R cells.
MeSH terms
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Alitretinoin
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Apoptosis / drug effects*
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Apoptosis / physiology
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Blotting, Western
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Butadienes / pharmacology
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Cell Proliferation / drug effects
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Drug Resistance, Neoplasm*
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Drug Therapy, Combination
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Enzyme Inhibitors / pharmacology
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Flavonoids / pharmacology
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HL-60 Cells
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Humans
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Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors*
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Mitogen-Activated Protein Kinase Kinases / metabolism
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Nitriles / pharmacology
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Phosphorylation / drug effects
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Retinoid X Receptor alpha / metabolism*
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Tretinoin / pharmacology*
Substances
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Butadienes
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Enzyme Inhibitors
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Flavonoids
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Nitriles
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Retinoid X Receptor alpha
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U 0126
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Alitretinoin
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Tretinoin
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Mitogen-Activated Protein Kinase Kinases
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2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one