3065

HDAC1

Downregulation of E-cadherin by the transcriptional repressor Snail is associated with acquisition of metastatic potential. Although hepatitis C virus (HCV) core protein has been implicated in hepatocarcinogenesis, it is unclear whether Snail is involved in HCV core-induced dysregulation of E-cadherin. Herein, we investigated the mechanism by which HCV core induces E-cadherin repression and the role of Snail in HCV core-mediated invasiveness and metastasis. We found that HCV infection, especially HCV core expression, effectively induced the epithelial-mesenchymal transition (EMT) in hepatoma cells by repressing E-cadherin. HCV core interacted with Snail and enhanced its binding to the E-box in the promoter region of E-cadherin, leading to decreased E-cadherin promoter activity. We found that HCV core, Snail, and the histone deacetylases HDAC1/HDAC2 formed a co-repressor complex at the E-cadherin promoter. Moreover, HCV core was shown to stabilize Snail through activation of the PI3K/Akt/GSK3beta pathway. Silencing Snail expression restored E-cadherin expression and inhibited HCV core-promoted tumor growth and distant lung metastasis in vivo. Collectively, these results demonstrated that HCV core induced EMT by interacting with the transcriptional repressor complex Snail/HDACs at the E-cadherin promoter, which led to E-cadherin repression and increased invasiveness of hepatoma cells. These findings increase understanding of factors regulating metastasis in hepatoma and may ultimately lead to the development of novel treatment strategies for HCV-associated hepatocellular carcinoma.

epithelial to mesenchymal transition (EMT)(1) occurs naturally during embryogenesis, tissue repair, cancer progression, and metastasis. EMT induces cellular and microenvironmental changes resulting in loss of epithelial and acquisition of mesenchymal phenotypes, which promotes cellular invasive and migratory capabilities. EMT can be triggered by extracellular factors, including TGF-beta, HGF, and EGF. Overexpression of transcription factors, such as SNAIL, SLUG, ZEB1/2, and TWIST1, also induces EMT and is correlated to cancer aggressiveness. Here, the breast adenocarcinoma cell line MCF7 was transduced with SNAIL to identify specific mechanisms controlled by this transcription factor during EMT. Overexpression of SNAIL led to EMT, which was thoroughly validated by molecular, morphological, and functional experiments. Subcellular proteome enrichment followed by GEL-LC-MS/MS was performed to provide extensive protein fractionation and in-depth proteomic analysis. Quantitative analysis relied on a SILAC strategy, using the invasive breast cancer cell line MDA-MB-231 as a reference for quantitation. Subsets of proteins enriched in each subcellular compartment led to a complementary list of 4289 proteins identified with high confidence. A subset of differentially expressed proteins was validated by Western blot, including regulation in specific cellular compartments, potentially caused by protein translocation. Protein network analysis highlighted complexes involved in cell cycle control and epigenetic regulation. Flow cytometry analysis indicated that SNAIL overexpression led to cell cycle arrest in G0/G1 phases. Furthermore, down-regulation of HDAC1 was observed, supporting the involvement of epigenetic processes in SNAIL-induced EMT. When HDAC1 activity was inhibited, MCF7 not only apparently initiated EMT but also up-regulated SNAIL, indicating the cross-talk between these two proteins. Both HDAC1 inhibition and SNAIL overexpression activated the AKT pathway. These molecular mechanisms appear to be essential to EMT and therefore for cancer metastasis. Specific control of such epigenetic processes might then represent effective approaches for clinical management of metastatic cancer.CI - (c) 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

BACKGROUND HDAC1 has been shown to be closely associated with the occurrence of tumors. We aimed to investigate the effects of siRNA-mediated HDAC1 knockdown on the biological behavior of esophageal carcinoma cell lines. MATERIAL AND METHODS HDAC1 expression in esophageal cancer cell lines TE-1, Eca109, and EC9706 was compared by Western blot analysis. These cells were transfected with siRNA-HDAC1 and cell proliferation was evaluated by MTT assay to select the optimum cell line for subsequent experiments. The effects of siRNA-HDAC1 on the migration and invasion of the selected cell line were assessed by transwell assay. The expression of cell cycle-related proteins cyclinD1, p21 and p27, and epithelial-mesenchymal transition (EMT)-related protein zonula occludens-1 (ZO-1), E-cadherin and vimentin was determined by Western blot analysis. RESULTS HDAC1 expression in TE-1, Eca109 and EC9706 cells was significantly higher compared with normal esophageal cell line HEEC (P<0.01). MTT assay, Western blot and RT-PCR analyses demonstrated that the inhibitory effects of siRNA on HDAC1 expression and cell viability in TE-1 cells were the highest among all cell lines, which was therefore used in subsequent experiments. After TE-1 cells were transfected with siRNA-HDAC1, their migration and invasion were significantly lower compared with the controls (P<0.01). CyclinD1 and vimentin expression was significantly lower compared with the controls (P<0.01), whereas the expression of p21, p27, ZO-1 and E-cadherin was significantly higher (P<0.01). CONCLUSIONS The siRNA-mediated HDAC1 knockdown significantly inhibited the proliferation, migration and invasion of TE-1 cells probably by regulating the expression of cell cycle- and EMT-related proteins.

The identification of prognostic markers for gallbladder cancer is needed for clinical practice. Histone deacetylases (HDACs) play an important role in tumor development and progression by modifying histone and non-histone proteins. However, the expression of HDAC1 in patients with gallbladder cancer is still unknown. Here, we reported that HDAC1 expression was elevated in cancerous tissue and correlated with lymph node metastasis and poorer overall survival in patients with GBC. Knockdown of HDAC1 using lentivirus delivery of HDAC1-specific shRNA abrogated the migration and invasion of GBC cells in vitro. TCF-12, as the HDAC1 binding protein, has also correlates with poor prognosis in GBC patients. And there is a positive correlation between HDAC1 and TCF-12 which leading the high invasion and migration ability of GBC cells. Taken together, our data suggested that HDAC1 and TCF-12 are a potential prognostic maker and may be a molecular target for inhibiting invasion and metastasis in GBC.

epithelial-mesenchymal transition (EMT) and renal fibrosis are closely involved in chronic kidney disease. Inhibition of histone deacetylase (HDAC) has an anti-fibrotic effect in various diseases. However, the pathophysiological role of isoform-specific HDACs or class-selective HDACs in renal fibrosis remains unknown. Here, we investigated EMT markers and extracellular matrix (ECM) proteins in a human proximal tubular cell line (HK-2) by using HDAC inhibitors or by knockdown of class I HDACs (HDAC1, 2, 3 and 8). Trichostatin A (TSA), MS275, PCI34051 and LMK235 inhibited ECM proteins such as collagen type I or fibronectin in transforming growth factor beta1 (TGF-beta1)-induced HK2 cells. However, restoration of TGF-beta1-induced E-cadherin down-regulation was only seen in HK-2 cells treated with TSA or MS275, but not with PCI34051, whereas TGF-beta1-induced N-cadherin expression was not affected by the inhibitors. ECM protein and EMT marker levels were prevented or restored by small interfering RNA transfection against HDAC8, but not against other class I HDACs (HDAC1, 2 and 3). E-cadherin regulation is mediated by HDAC8 expression, but not by HDAC8 enzyme activity. Thus, class I HDACs (HDAC1, 2, 3 and 8) play a major role in regulating ECM and EMT, whereas class IIa HDACs (HDAC4 and 5) are less effective.CI - (c) 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Hypoxia is a major driving force of cancer invasion and metastasis. Here we show that death domain-associated protein (Daxx) acts to negatively regulate hypoxia-induced cell dissemination and invasion by inhibiting the HIF-1alpha/HDAC1/Slug pathway. Daxx directly binds to the DNA-binding domain of Slug, impeding histone deacetylase 1 (HDAC1) recruitment and antagonizing Slug E-box binding. This, in turn, stimulates E-cadherin and occludin expression and suppresses Slug-mediated epithelial-mesenchymal transition (EMT) and cell invasiveness. Under hypoxic conditions, stabilized hypoxia-inducible factor (HIF)-1alpha downregulates Daxx expression and promotes cancer invasion, whereas re-expression of Daxx represses hypoxia-induced cancer invasion. Daxx also suppresses Slug-mediated lung cancer metastasis in an orthotopic lung metastasis mouse model. Using clinical tumour samples, we confirmed that the HIF-1alpha/Daxx/Slug pathway is an outcome predictor. Our results support that Daxx can act as a repressor in controlling HIF-1alpha/HDAC1/Slug-mediated cancer cell invasion and is a potential therapeutic target for inhibition of cancer metastasis.