Abstract
The Rb/E2F pathway regulates the expression of genes essential for cell proliferation but that also trigger apoptosis. During normal proliferation, PI3K/Akt signaling blocks E2F1-induced apoptosis, thus serving to balance proliferation and death. We now identify a subset of E2F1 target genes that are specifically repressed by PI3K/Akt signaling, thus distinguishing the E2F1 proliferative or apoptotic function. RNAi-mediated inhibition of several of these PI3K-repressed E2F1 target genes, including AMPK alpha 2, impairs apoptotic induction by E2F1. Activation of AMPK alpha 2 with an AMP analog further stimulates E2F1-induced apoptosis. We also show that the presence of the E2F1 apoptotic expression program in breast and ovarian tumors coincides with good prognosis, emphasizing the importance of the balance in the E2F1 proliferation/apoptotic program.
MeSH terms
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AMP-Activated Protein Kinases
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Aminoimidazole Carboxamide / analogs & derivatives
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Aminoimidazole Carboxamide / pharmacology
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Animals
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Cell Death / drug effects
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Cell Line, Tumor
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Cell Proliferation / drug effects
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E2F1 Transcription Factor / metabolism*
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Enzyme Activation / drug effects
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Gene Expression Regulation, Neoplastic* / drug effects
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Genes, Neoplasm
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Humans
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Models, Biological
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Multienzyme Complexes / metabolism
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Neoplasms / enzymology
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Neoplasms / genetics
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Neoplasms / pathology
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Phenotype
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Phosphatidylinositol 3-Kinases / metabolism
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Protein Serine-Threonine Kinases / metabolism
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Rats
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Repressor Proteins / metabolism
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Ribonucleotides / pharmacology
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Serum
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Signal Transduction / drug effects
Substances
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E2F1 Transcription Factor
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Multienzyme Complexes
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Repressor Proteins
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Ribonucleotides
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Aminoimidazole Carboxamide
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PRKAA2 protein, human
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Protein Serine-Threonine Kinases
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AMP-Activated Protein Kinases
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AICA ribonucleotide