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Noh J.H.,Catholic University of Korea | Noh J.H.,Functional omics Research Center | Bae H.J.,Catholic University of Korea | Bae H.J.,Functional omics Research Center | And 21 more authors.
Cancer Research | Year: 2014

Aberrant regulation of histone deacetylase 2 (HDAC2) contributes to malignant progression in various cancers, but the underlying mechanism leading to the activation of oncogenic HDAC2 remains unknown. In this study, we show that HDAC2 expression is upregulated in a large cohort of patients with human hepatocellular carcinoma, and that high expression of HDAC2 was significantly associated with poor prognosis of patients with hepatocellular carcinoma. We found that mTORC1/NF-kBp50 signaling is necessary for the growth factor- induced HDAC2 and is sustained in hepatocellular carcinoma, but not in normal hepatic cells. Growth factor- induced mTORC1 activates the nuclear translocation of NF-kBp50, where it binds to the intragenic sequences of the HDAC2 gene and promotes its transcription. Hepatocellular carcinoma tissues derived from chemicalinduced mouse and rat liver cancer models validated that mTORC1 activation and NF-kBp50 nuclear translocation are essential for the transcriptional activation of oncogenic HDAC2 in hepatocellular carcinoma. In addition, we demonstrate that HDAC2 is required to maintain mTORC1 activity by stabilizing the mTOR/ RAPTOR complex. Elevated expression of HDAC2 triggers a positive feedback loop that activates AKT phosphorylation via the transcriptional modulation of phosphoinositide signaling molecules. Bioinformatics analysis of HDAC2 signature and immunoblot analysis of mesenchymal genes also evidenced that HDAC2 plays a role in the malignant behavior of tumor cells by Snail induction and simultaneously E-cadherin suppression in hepatocellular carcinoma cells. These findings establish a molecular mechanism responsible for the activation of oncogenic HDAC2, which explains how growth factor-induced HDAC2 maintains mitogenic signaling and function during hepatocellular malignant progression and provide a novel strategy for therapeutic intervention in liver cancer.©2014 American Association for Cancer Research.

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