Human Gene Set: PARENT_MTOR_SIGNALING_DN


Standard name PARENT_MTOR_SIGNALING_DN
Systematic name M16644
Brief description Genes down-regulated in HepaRG cells (liver cancer) expressing constituvely active form of MTOR [GeneID=2475].
Full description or abstract The mammalian target of rapamycin (mTOR) pathway, a major regulator of translation, is frequently activated in hepatocellular carcinomas. We investigated the effects of mTOR activation in the human HepaRG cells, which possess potent hepatocytic differentiation capability. Differentiation of HepaRG cells into functional and polarized hepatocyte-like cells correlated with a decrease in mTOR and Akt activities. Stable cell lines expressing an activated mutant of mTOR were generated. Sustained activation of mTOR impaired the hepatocytic differentiation capability of these cells as shown by impaired formation of bile canaliculi, absence of polarity, and reduced secretion of alpha1-antitrypsin. An inhibitor of mTOR, rapamycin, was able to revert this phenotype. Furthermore, increased mTOR activity in HepaRG cells resulted in their resistance to the antiproliferative effects of transforming growth factor-beta1. Profiling of polysome-bound transcripts indicated that activated mTOR specifically targeted genes posttranscriptionally regulated on hepatocytic differentiation. Three major biological networks targeted by activated mTOR were identified: (a) cell death associated with tumor necrosis factor superfamily members, IFNs and caspases; (b) lipid homeostasis associated with the transcription factors PPARalpha, PPARdelta, and retinoid X receptor beta; and (c) liver development associated with CCAAT/enhancer binding protein alpha and hepatic mitogens. In conclusion, increased mTOR activity conferred a preneoplastic phenotype to the HepaRG cells by altering the translation of genes vital for establishing normal hepatic energy homeostasis and moderating hepatocellular growth.
Collection C2: Curated
      CGP: Chemical and Genetic Perturbations
Source publication Pubmed 17483347   Authors: Parent R,Kolippakkam D,Booth G,Beretta L
Exact source Table 2S
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Source species Homo sapiens
Contributed by Arthur Liberzon (MSigDB Team)
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identifier namespace		 AFFY_HG_U133
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Version history 3.0: First introduced

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