Abstract
Hypoxia is a common feature of solid tumors, and the extent of tumor hypoxia correlates with advanced disease stages and treatment resistance. The transcription factor hypoxia-inducible factor-1 (HIF-1) represents an important tumor-selective molecular target for anticancer drug discovery directed at tumor hypoxia. A natural product chemistry-based approach was employed to discover small molecule inhibitors of HIF-1. Bioassay-guided isolation of an active lipid extract of the tropical legumaceous plant Lonchocarpus glabrescens and structure elucidation afforded two new HIF-1 inhibitors: alpinumisoflavone (compound 1) and 4'-O-methylalpinumisoflavone (compound 2). In human breast tumor T47D cells, compounds 1 and 2 inhibited hypoxia-induced HIF-1 activation with IC(50) values of 5 and 0.6 mum, respectively. At the concentrations that in hibited HIF-1 activation, compound 2 inhibited hypoxic induction of HIF-1 target genes (CDKN1A, GLUT-1, and VEGF), tumor angiogenesis in vitro, cell migration, and chemotaxis. Compound 2 inhibits HIF-1 activation by blocking the induction of nuclear HIF-1alpha protein, the oxygen-regulated subunit that controls HIF-1 activity. Mechanistic studies indicate that, unlike rotenone and other mitochondrial inhibitors, compound 2 represents the first small molecule that inhibits HIF-1 activation by simultaneously suppressing mitochondrial respiration and disrupting protein translation in vitro. This unique mechanism distinguishes compound 2 from other small molecule HIF-1 inhibitors that are simple mitochondrial inhibitors or flavanoid-based protein kinase inhibitors.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Blotting, Western
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Breast Neoplasms / blood supply
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Breast Neoplasms / drug therapy
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Breast Neoplasms / metabolism
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Cell Hypoxia
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Cell Movement / drug effects*
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Cell Proliferation
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Cell Respiration / drug effects
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Cell Respiration / physiology
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Cell Survival / drug effects
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Cells, Cultured
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Chemotaxis
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Cyclin-Dependent Kinase Inhibitor p21 / genetics
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Cyclin-Dependent Kinase Inhibitor p21 / metabolism*
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Endothelium, Vascular / cytology
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Endothelium, Vascular / drug effects
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Endothelium, Vascular / metabolism
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Enzyme-Linked Immunosorbent Assay
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Fabaceae / chemistry
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Glucose Transporter Type 1 / genetics
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Glucose Transporter Type 1 / metabolism*
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Humans
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Hypoxia-Inducible Factor 1, alpha Subunit / antagonists & inhibitors*
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Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
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Isoflavones / pharmacology*
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Male
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Mitochondria / drug effects
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Mitochondria / metabolism
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Neovascularization, Pathologic
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Oxygen Consumption / drug effects
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Prostatic Neoplasms / blood supply
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Prostatic Neoplasms / drug therapy
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Prostatic Neoplasms / metabolism
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Protein Biosynthesis
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Umbilical Veins / cytology
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Umbilical Veins / drug effects
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Umbilical Veins / metabolism
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Vascular Endothelial Growth Factor A / genetics
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Vascular Endothelial Growth Factor A / metabolism*
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Wound Healing
Substances
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4'-O-methylalpinumisoflavone
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CDKN1A protein, human
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Cyclin-Dependent Kinase Inhibitor p21
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Glucose Transporter Type 1
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HIF1A protein, human
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Hypoxia-Inducible Factor 1, alpha Subunit
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Isoflavones
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VEGFA protein, human
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Vascular Endothelial Growth Factor A
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alpinumisoflavone