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Carbajo-Pescador S.,University of Leon | Ordonez R.,University of Leon | Benet M.,Research Center Biomedica En Red Of Enfermedades Hepaticas gestivas | Benet M.,Experimental Hepatology Unit | And 8 more authors.
British Journal of Cancer | Year: 2013

Background:Hepatocellular carcinoma (HCC) growth relies on angiogenesis via vascular endothelial growth factor (VEGF) release. Hypoxia within tumour environment leads to intracellular stabilisation of hypoxia inducible factor 1 alpha (Hif1α) and signal transducer and activator of transcription (STAT3). Melatonin induces apoptosis in HCC, and shows anti-angiogenic features in several tumours. In this study, we used human HepG2 liver cancer cells as an in vitro model to investigate the anti-angiogenic effects of melatonin.Methods:HepG2 cells were treated with melatonin under normoxic or CoCl 2 -induced hypoxia. Gene expression was analysed by RT-qPCR and western blot. Melatonin-induced anti-angiogenic activity was confirmed by in vivo human umbilical vein endothelial cells (HUVECs) tube formation assay. Secreted VEGF was measured by ELISA. Immunofluorescence was performed to analyse Hif1α cellular localisation. Physical interaction between Hif1α and its co-activators was analysed by immunoprecipitation and chromatin immunoprecipitation (ChIP).Results:Melatonin at a pharmacological concentration (1 mM) decreases cellular and secreted VEGF levels, and prevents HUVECs tube formation under hypoxia, associated with a reduction in Hif1α protein expression, nuclear localisation, and transcriptional activity. While hypoxia increases phospho-STAT3, Hif1α, and CBP/p300 recruitment as a transcriptional complex within the VEGF promoter, melatonin 1 mM decreases their physical interaction. Melatonin and the selective STAT3 inhibitor Stattic show a synergic effect on Hif1α, STAT3, and VEGF expression.Conclusion: Melatonin exerts an anti-angiogenic activity in HepG2 cells by interfering with the transcriptional activation of VEGF, via Hif1α and STAT3. Our results provide evidence to consider this indole as a powerful anti-angiogenic agent for HCC treatment. © 2013 Cancer Research UK. All rights reserved.


Pisonero-Vaquero S.,University of Leon | Martinez-Ferreras A.,University of Leon | Garcia-Mediavilla M.V.,University of Leon | Garcia-Mediavilla M.V.,CIBER ISCIII | And 13 more authors.
Molecular Nutrition and Food Research | Year: 2015

Scope: Flavonoids and related compounds seem to have favorable effects on nonalcoholic fatty liver disease (NAFLD) progression, although the exact mechanisms implicated are poorly understood. In this study, we aimed to investigate the effect of the flanovol quercetin on gene expression deregulation involved in the development of NAFLD, as well as the possible implication of phosphatidylinositol 3-kinase (PI3K)/AKT pathway modulation. Methods and results: We used an in vivo model based on methionine- and choline-deficient (MCD) diet-fed mice and an in vitro model consisting of Huh7 cells incubated with MCD medium. MCD-fed mice showed classical pathophysiological characteristics of nonalcoholic steatohepatitis, associated with altered transcriptional regulation of fatty acid uptake- and trafficking-related gene expression, with increased lipoperoxidation. PI3K/AKT pathway was activated by MCD and triggered gene deregulation causing either activation or inhibition of all studied genes as demonstrated through cell incubation with the PI3K-inhibitor LY294002. Treatment with quercetin reduced AKT phosphorylation, and oxidative/nitrosative stress, inflammation and lipid metabolism-related genes displayed a tendency to normalize in both in vivo and in vitro models. Conclusion: These results place quercetin as a potential therapeutic strategy for preventing NAFLD progression by attenuating gene expression deregulation, at least in part through PI3K/AKT pathway inactivation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Pisonero-Vaquero S.,University of Leon | Garcia-Mediavilla M.V.,University of Leon | Garcia-Mediavilla M.V.,CIBER ISCIII | Jorquera F.,CIBER ISCIII | And 12 more authors.
Laboratory Investigation | Year: 2014

There is experimental evidence that some antioxidant flavonoids show therapeutic potential in the treatment of hepatitis C through inhibition of hepatitis C virus (HCV) replication. We examined the effect of treatment with the flavonols quercetin and kaempferol, the flavanone taxifolin and the flavone apigenin on HCV replication efficiency in an in vitro model. While all flavonoids studied were able to reduce viral replication at very low concentrations (ranging from 0.1 to 5 μM), quercetin appeared to be the most effective inhibitor of HCV replication, showing a marked anti-HCV activity in replicon-containing cells when combined with interferon (IFN)α. The contribution of oxidative/nitrosative stress and lipogenesis modulation to inhibition of HCV replication by quercetin was also examined. As expected, quercetin decreased HCV-induced reactive oxygen and nitrogen species (ROS/RNS) generation and lipoperoxidation in replicating cells. Quercetin also inhibited liver X receptor (LXR)α-induced lipid accumulation in LXRα- overexpressing and replicon-containing Huh7 cells. The mechanism underlying the LXRα-dependent lipogenesis modulatory effect of quercetin in HCV-replicating cells seems to involve phosphatidylinositol 3-kinase (PI3K)/AKT pathway inactivation. Thus, inhibition of the PI3K pathway by LY294002 attenuated LXRα upregulation and HCV replication mediated by lipid accumulation, showing an additive effect when combined with quercetin. Inactivation of the PI3K pathway by quercetin may contribute to the repression of LXRα-dependent lipogenesis and to the inhibition of viral replication induced by the flavonol. Combined, our data suggest that oxidative/nitrosative stress blockage and subsequent modulation of PI3K-LXRα-mediated lipogenesis might contribute to the inhibitory effect of quercetin on HCV replication. © 2014 USCAP, Inc.


Benet M.,Experimental Hepatology Unit | Benet M.,CIBER ISCIII | Guzman C.,Experimental Hepatology Unit | Pisonero-Vaquero S.,University of Leon | And 14 more authors.
Molecular Pharmacology | Year: 2015

The small heterodimer partner (SHP) (NR0B2) is an atypical nuclear receptor that lacks a DNA-binding domain. It interacts with and inhibits many transcription factors, affecting key metabolic processes, including bile acid, cholesterol, fatty acid, and drug metabolism. Our aim was to determine the influence of steatotic drugs and nonalcoholic fatty liver disease (NAFLD) on SHP expression and investigate the potential mechanisms. SHP was found to be repressed by steatotic drugs (valproate, doxycycline, tetracycline, and cyclosporin A) in cultured hepatic cells and the livers of different animal models of NAFLD: iatrogenic (tetracycline-treated rats), genetic (glycine N-methyltransferase-deficient mice), and nutritional (mice fed a methionine- and choline-deficient diet). Among the different transcription factors investigated, CCAATenhancerbinding protein α (C/EBPα) showed the strongest dominant-repressive effect on SHP expression in HepG2 and human hepatocytes. Reporter assays revealed that the inhibitory effect of C/EBPα and steatotic drugs colocalize between 2340 and 2509 base pair of the SHP promoter, and mutation of a predicted C/EBPα response element at2473 base pair abolished SHP repression by both C/EBPα and drugs. Moreover, inhibition of major stress signaling pathways demonstrated that the mitogen-activated protein kinase kinase 1/2 pathway activates, while the phosphatidylinositol 3 kinase pathway represses SHP in a C/EBP-dependent manner. We conclude that SHP is downregulated by several steatotic drugs and in advanced NAFLD. These conditions can activate signals that target C/EBPα and consequently repress SHP, thus favoring the progression and severity of NAFLD. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.


Guzman C.,Experimental Hepatology Unit | Benet M.,Experimental Hepatology Unit | Benet M.,CIBER ISCIII | Pisonero-Vaquero S.,University of Leon | And 15 more authors.
Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids | Year: 2013

Liver fatty acid binding protein (FABP1) prevents lipotoxicity of free fatty acids and regulates fatty acid trafficking and partition. Our objective is to investigate the transcription factors controlling the human FABP1 gene and their regulation in nonalcoholic fatty liver disease (NAFLD). Adenovirus-mediated expression of multiple transcription factors in HepG2 cells and cultured human hepatocytes demonstrated that FOXA1 and PPARα are among the most effective activators of human FABP1, whereas C/EBPα is a major dominant repressor. Moreover, FOXA1 and PPARα induced re-distribution of FABP1 protein and increased cytoplasmic expression. Reporter assays demonstrated that the major basal activity of the human FABP1 promoter locates between - 96 and - 229 bp, where C/EBPα binds to a composite DR1-C/EBP element. Mutation of this element at - 123 bp diminished basal reporter activity, abolished repression by C/EBPα and reduced transactivation by HNF4α. Moreover, HNF4α gene silencing by shRNA in HepG2 cells caused a significant down-regulation of FABP1 mRNA expression. FOXA1 activated the FABP1 promoter through binding to a cluster of elements between - 229 and - 592 bp, whereas PPARα operated through a conserved proximal element at - 59 bp. Finally, FABP1, FOXA1 and PPARα were concomitantly repressed in animal models of NAFLD and in human nonalcoholic fatty livers, whereas C/EBPα was induced or did not change. We conclude that human FABP1 has a complex mechanism of regulation where C/EBPα displaces HNF4α and hampers activation by FOXA1 and PPARα. Alteration of expression of these transcription factors in NAFLD leads to FABP1 gen repression and could exacerbate lipotoxicity and disease progression. © 2013 Elsevier B.V.

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