Abstract
Loss of the promyelocytic leukaemia (PML) tumour suppressor has been observed in several human cancers. The tumour-suppressive function of PML has been attributed to its ability to induce growth arrest, cellular senescence and apoptosis. Here we identify PML as a critical inhibitor of neoangiogenesis (the formation of new blood vessels) in vivo, in both ischaemic and neoplastic conditions, through the control of protein translation. We demonstrate that in hypoxic conditions PML acts as a negative regulator of the synthesis rate of hypoxia-inducible factor 1alpha (HIF-1alpha) by repressing mammalian target of rapamycin (mTOR). PML physically interacts with mTOR and negatively regulates its association with the small GTPase Rheb by favouring mTOR nuclear accumulation. Notably, Pml-/- cells and tumours display higher sensitivity both in vitro and in vivo to growth inhibition by rapamycin, and lack of PML inversely correlates with phosphorylation of ribosomal protein S6 and tumour angiogenesis in mouse and human tumours. Thus, our findings identify PML as a novel suppressor of mTOR and neoangiogenesis.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Animals
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Cell Hypoxia / physiology
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Cell Line, Tumor
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Cell Nucleus / metabolism
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Fibroblasts
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Humans
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Hypoxia-Inducible Factor 1, alpha Subunit / biosynthesis*
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Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
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Ischemia / genetics
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Ischemia / metabolism
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Mice
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Monomeric GTP-Binding Proteins / metabolism
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Neoplasm Proteins / deficiency
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism*
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Neoplasms / blood supply
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Neoplasms / genetics
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Neoplasms / metabolism
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Neovascularization, Pathologic*
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Neuropeptides / metabolism
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Nuclear Proteins / deficiency
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Phosphorylation
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Promyelocytic Leukemia Protein
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Protein Binding
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Protein Biosynthesis*
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Protein Kinases / metabolism*
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Ras Homolog Enriched in Brain Protein
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Repressor Proteins / metabolism*
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Ribosomal Protein S6 / metabolism
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Sirolimus / pharmacology
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TOR Serine-Threonine Kinases
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Transcription Factors / deficiency
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Tumor Suppressor Proteins / deficiency
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism*
Substances
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Hif1a protein, mouse
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Hypoxia-Inducible Factor 1, alpha Subunit
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Neoplasm Proteins
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Neuropeptides
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Nuclear Proteins
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Pml protein, mouse
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Promyelocytic Leukemia Protein
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Ras Homolog Enriched in Brain Protein
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Repressor Proteins
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Rheb protein, mouse
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Ribosomal Protein S6
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Transcription Factors
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Tumor Suppressor Proteins
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PML protein, human
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Protein Kinases
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MTOR protein, human
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mTOR protein, mouse
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TOR Serine-Threonine Kinases
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Monomeric GTP-Binding Proteins
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Sirolimus