Abstract
Inhibitors of the mechanistic target of rapamycin (mTOR) are currently used to treat advanced metastatic breast cancer. However, whether an aggressive phenotype is sustained through adaptation or resistance to mTOR inhibition remains unknown. Here, complementary studies in human tumors, cancer models and cell lines reveal transcriptional reprogramming that supports metastasis in response to mTOR inhibition. This cancer feature is driven by EVI1 and SOX9. EVI1 functionally cooperates with and positively regulates SOX9, and promotes the transcriptional upregulation of key mTOR pathway components (REHB and RAPTOR) and of lung metastasis mediators (FSCN1 and SPARC). The expression of EVI1 and SOX9 is associated with stem cell-like and metastasis signatures, and their depletion impairs the metastatic potential of breast cancer cells. These results establish the mechanistic link between resistance to mTOR inhibition and cancer metastatic potential, thus enhancing our understanding of mTOR targeting failure.
MeSH terms
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Adaptor Proteins, Signal Transducing / genetics
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Adult
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Aged
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Breast Neoplasms / genetics*
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Breast Neoplasms / pathology
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Carrier Proteins / genetics
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Cell Proliferation / genetics
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DNA-Binding Proteins / genetics*
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Female
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Gene Expression Regulation, Neoplastic
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Humans
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Lung Neoplasms / genetics*
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Lung Neoplasms / pathology
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Lung Neoplasms / secondary
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MCF-7 Cells
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MDS1 and EVI1 Complex Locus Protein
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Microfilament Proteins / genetics
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Middle Aged
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Neoplasm Metastasis
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Osteonectin / genetics
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Proto-Oncogenes / genetics*
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Regulatory-Associated Protein of mTOR
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SOX9 Transcription Factor / genetics*
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Signal Transduction / genetics
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TOR Serine-Threonine Kinases / antagonists & inhibitors
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TOR Serine-Threonine Kinases / genetics*
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Transcription Factors / genetics*
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Xenograft Model Antitumor Assays
Substances
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Adaptor Proteins, Signal Transducing
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Carrier Proteins
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DNA-Binding Proteins
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FSCN1 protein, human
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MDS1 and EVI1 Complex Locus Protein
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MECOM protein, human
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Microfilament Proteins
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Osteonectin
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RPTOR protein, human
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Regulatory-Associated Protein of mTOR
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SOX9 Transcription Factor
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SOX9 protein, human
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SPARC protein, human
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Transcription Factors
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MTOR protein, human
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TOR Serine-Threonine Kinases