Reprogramming of Glutamine Amino Acid Transporters Expression and Prognostic Significance in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the most prevalent primary liver malignancy and is a major cause of cancer-related mortality in the world. This study aimed to characterize glutamine amino acid transporter expression profiles in HCC compared to those of normal liver cells. In vitro and in vivo models of HCC were studied using qPCR, whereas the prognostic significance of glutamine transporter expression levels within patient tumors was analyzed through RNAseq.

Impact of the delay in cryopreservation timing during biobanking procedures on human liver tissue metabolomics.

The liver is a highly specialized organ involved in regulating systemic metabolism. Understanding metabolic reprogramming of liver disease is key in discovering clinical biomarkers, which relies on robust tissue biobanks. However, sample collection and storage procedures pose a threat to obtaining reliable results, as metabolic alterations may occur during sample handling.

Metabolomics-Guided Identification of a Distinctive Hepatocellular Carcinoma Signature.

Background: Hepatocellular carcinoma (HCC) is a major contributor to cancer-related morbidity and mortality burdens globally. Given the fundamental metabolic activity of hepatocytes within the liver, hepatocarcinogenesis is bound to be characterized by alterations in metabolite profiles as a manifestation of metabolic reprogramming.

Methods: HCC and adjacent non-tumoral liver specimens were obtained from patients after HCC resection.

MYC Rules: Leading Glutamine Metabolism toward a Distinct Cancer Cell Phenotype.

Metabolic reprogramming and deregulated cellular energetics are hallmarks of cancer. The aberrant metabolism of cancer cells is thought to be the product of differential oncogene activation and tumor suppressor gene inactivation. MYC is one of the most important oncogenic drivers, its activation being reported in a variety of cancer types and sub-types, among which are the most prevalent and aggressive of all malignancies.

Oxaloacetate Protects Rat Liver From Experimental Warm Ischemia/Reperfusion Injury by Improving Cellular Energy Metabolism.

Liver ischemia/reperfusion injury (IRI) is an important cause of liver damage especially early after liver transplantation, following liver resection, and in other clinical situations. Using rat experimental models, we identified oxaloacetate (OAA) as a key metabolite able to protect hepatocytes from hypoxia and IRI. In vitro screening of metabolic intermediates beneficial for hepatocyte survival under hypoxia was performed by measures of cell death and injury.

Metabolite profiling identifies a signature of tumorigenicity in hepatocellular carcinoma.

HCC (Hepatocellular carcinoma) cells exhibit greater metabolic plasticity than normal hepatocytes since they must survive in a dynamic microenvironment where nutrients and oxygen are often scarce. Using a metabolomic approach combined with functional and assays, we aimed to identify an HCC metabolic signature associated with increased tumorigenicity and patient mortality. Metabolite profiling of HCC Dt81Hepa1-6 cells revealed that their increased tumorigenicity was associated with elevated levels of glycolytic metabolites.

Upregulation of Krebs cycle and anaerobic glycolysis activity early after onset of liver ischemia.

The liver is a highly vascularized organ receiving a dual input of oxygenated blood from the hepatic artery and portal vein. The impact of decreased blood flow on glucose metabolism and how hepatocytes could adapt to this restrictive environment are still unclear. Using the left portal vein ligation (LPVL) rat model, we found that cellular injury was delayed after the onset of liver ischemia.

Metabolic reprogramming enables hepatocarcinoma cells to efficiently adapt and survive to a nutrient-restricted microenvironment.

Hepatocellular carcinoma (HCC) is a metabolically heterogeneous cancer and the use of glucose by HCC cells could impact their tumorigenicity. Dt81Hepa1-6 cells display enhanced tumorigenicity compared to parental Hepa1-6 cells. This increased tumorigenicity could be explained by a metabolic adaptation to more restrictive microenvironments.

From in vivo to in vitro: Major metabolic alterations take place in hepatocytes during and following isolation.

The liver plays a key role in maintaining physiological homeostasis and hepatocytes are largely responsible for this. The use of isolated primary hepatocytes has become an essential tool for the study of nutrient physiology, xenobiotic metabolism and several liver pathologies. Since hepatocytes are removed from their normal environment, the isolation procedure and in vitro culture of primary hepatocytes is partially known to induce undesired metabolic changes.

Highly tumorigenic hepatocellular carcinoma cell line with cancer stem cell-like properties.

There are limited numbers of models to study hepatocellular carcinoma (HCC) in vivo in immunocompetent hosts. In an effort to develop a cell line with improved tumorigenicity, we derived a new cell line from Hepa1-6 cells through an in vivo passage in C57BL/6 mice. The resulting Dt81Hepa1-6 cell line showed enhanced tumorigenicity compared to Hepa1-6 with more frequent (28±12 vs.

Protection against Acute Hepatocellular Injury Afforded by Liver Fibrosis Is Independent of T Lymphocytes.

Collagen produced during the process of liver fibrosis can induce a hepatocellular protective response through ERK1 signalling. However, the influence of T cells and associated cytokine production on this protection is unknown. In addition, athymic mice are frequently used in hepatocellular carcinoma xenograft experiments but current methods limit our ability to study the impact of liver fibrosis in this setting due to high mortality.

Genome-wide RNAi screen reveals a new role of a WNT/CTNNB1 signaling pathway as negative regulator of virus-induced innate immune responses.

To identify new regulators of antiviral innate immunity, we completed the first genome-wide gene silencing screen assessing the transcriptional response at the interferon-β (IFNB1) promoter following Sendai virus (SeV) infection. We now report a novel link between WNT signaling pathway and the modulation of retinoic acid-inducible gene I (RIG-I)-like receptor (RLR)-dependent innate immune responses. Here we show that secretion of WNT2B and WNT9B and stabilization of β-catenin (CTNNB1) upon virus infection negatively regulate expression of representative inducible genes IFNB1, IFIT1 and TNF in a CTNNB1-dependent effector mechanism.

Hepatocellular apoptosis in mice is associated with early upregulation of mitochondrial glucose metabolism.

Hepatocyte death due to apoptosis is a hallmark of almost every liver disease. Manipulation of cell death regulatory steps during the apoptotic process is therefore an obvious goal of biomedical research. To clarify whether metabolic changes occur prior to the characteristic apoptotic events, we used ex vivo multinuclear NMR-spectroscopy to study metabolic pathways of [U-(13)C]glucose in mouse liver during Fas-induced apoptosis.

Liver fibrosis protects mice from acute hepatocellular injury.

Background & Aims: Development of fibrosis is part of the pathophysiologic process of chronic liver disease. Although it is considered deleterious, it also represents a form of tissue repair. Deposition of extracellular matrix changes the cellular environment of the liver; we investigated whether it increases resistance to noxious stimuli and the role of changes in intracellular signaling to hepatocytes in mediating this effect.

Targeted impairment of innate antiviral responses in the liver of chronic hepatitis C patients.

Background & Aims: Innate sensing of viral infection activates a global defense response including type I interferon (IFN) and IFN-stimulated genes (ISGs) expression. We previously reported that HCV NS3/4A protease, an essential protein in viral polyprotein processing, can abrogate antiviral signaling pathways and effectors' response when ectopically expressed in human hepatocytes by cleaving antiviral adaptor CARDIF. However, whether HCV mediates evasion of innate immunity in patients with chronic infection remains unclear.

Expression of E1E2 on hepatitis C RNA-containing particles released from primary cultured human hepatocytes derived from infected cirrhotic livers.

Objective: To determine whether liver-derived hepatitis C RNA-containing particles express the E1E2 discontinuous antigenic determinant defined by unique monoclonal antibody (mAb) D32.10 which recognizes three highly conserved segments in E1 (aa297-306) and E2 (aa480-494 and aa613-621) envelope glycoproteins.

Methods: Human hepatocytes were isolated from HCV-infected cirrhotic explanted livers.

Distinct antiviral signaling pathways in primary human hepatocytes and their differential disruption by HCV NS3 protease.

Background & Aims: Molecular sensors recognize viral nucleic acids and initiate events that subsequently enable cells to control and clear infection. Hepatitis C Virus (HCV) can interfere with the innate host response and the NS3/4A protease was reported to specifically block antiviral signaling pathways, a finding that had yet to be studied in human primary hepatocytes.

Methods: Freshly isolated human primary hepatocytes, transduced with a lentiviral vector expressing HCV NS3/4A were stimulated with extracellular and intracellular double-stranded RNA (dsRNA) and the innate immune antiviral genes were quantified by quantitative PCR and microarrays analysis.

Primary cultures of human hepatocytes isolated from hepatitis C virus-infected cirrhotic livers as a model to study hepatitis C infection.

Background/aim: Since the discovery of hepatitis C virus (HCV), researchers have encountered difficulties with in vitro models. The aim of this study was to determine whether HCV-infected human primary hepatocytes, isolated from cirrhotic livers at liver transplantation, can be used as a model to study HCV infection.

Methods: Hepatocytes were isolated with collagenase and cultured over a 20-day period on different matrices.

Repression of repulsive guidance molecule C during inflammation is independent of Hfe and involves tumor necrosis factor-alpha.

Genetic iron overload, or hemochromatosis, can be caused by mutations in HFE, hemojuvelin, and hepcidin genes. Hepcidin, a negative regulator of intestinal iron absorption, is found to be inappropriately low in both patients and in animal models, indicating that proper control of basal hepcidin levels requires both hemojuvelin and HFE. In mice, repulsive guidance molecule c (Rgmc, the hemojuvelin mouse ortholog) and hepcidin levels are transcriptionally regulated during inflammation.

Distinct requirements for Hfe in basal and induced hepcidin levels in iron overload and inflammation.

Hepcidin is a negative regulator of iron absorption produced mainly by the liver in response to changes in iron stores and inflammation, and its levels have been shown to regulate the intestinal basolateral iron transporter ferroportin1 (Fp1). Hereditary hemochromatosis patients and Hfe-deficient mice show inappropriate expression of hepcidin but, in apparent contradiction, still retain the ability to regulate iron absorption in response to alterations of iron metabolism. To further understand the molecular relationships among Hfe, hepcidin, and Fp1, we investigated hepcidin and Fp1 regulation in Hfe-deficient mice (Hfe-/- and beta2m-/-) in response to iron deprivation, iron loading, and acute inflammation.

Antiapoptotic effect of EGF on mouse hepatocytes associated with downregulation of proapoptotic Bid protein.

Growth factors have been shown to protect cells from a variety of apoptotic stimuli. In the liver, the Fas system is thought to be very important in the genesis of hepatocyte apoptosis. Others have already shown the importance of the phosphatidylinositol 3-kinase (PI3-kinase) pathway and of increased Bcl-xl expression in the antiapoptotic effect of growth factors on hepatocytes.