Human Hepatoma Cell Lines (human + hepatoma_cell_line)

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Selected Abstracts

Hepatitis C virus escape from the interferon regulatory factor 3 pathway by a passive and active evasion strategy,

HEPATOLOGY, Issue 5 2007
Marco Binder
Hepatitis C virus (HCV) has been known to replicate with extremely varying efficiencies in different host cells, even within different populations of a single human hepatoma cell line, termed Huh-7. Several reports have implicated the retinoic-acid inducible gene I (RIG-I)/ interferon regulatory factor 3 (IRF-3) pathway of the innate antiviral response with differences in host cell permissiveness to HCV. To investigate the general impact of the IRF-3 response onto HCV replication in cell culture, we generated an ample array of stable Huh-7 cell lines with altered IRF-3 responsiveness. Neither blocking IRF-3 activation in various host cells by expression of dominant negative RIG-I or HCV NS3/4A protease nor reconstitution of RIG-I signaling in Huh7.5, a cell clone known to be defective in this pathway, had any impact on HCV replication. Only by overexpressing constitutively active RIG-I or the signaling adaptor Cardif (also known as interferon-beta promoter stimulator 1, mitochondrial anti-viral signaling protein, or virus-induced signaling adaptor), both leading to a stimulation of the IRF-3 pathway in the absence of inducers, was HCV replication significantly inhibited. We therefore assessed the extent of RIG-I, dependent IRF-3 activation by different species of RNA, including full-length HCV genomes and HCV RNA duplexes, and observed strong induction only in response to double-stranded RNAs. Conclusion: Based on these findings, we propose a refined model of innate immune escape by HCV involving limited initial induction and stringent subsequent control of the IRF-3 response. (HEPATOLOGY 2007.) [source]

Involvement of p38 mitogen-activated protein kinase pathway in honokiol-induced apoptosis in a human hepatoma cell line (hepG2)

Junfang Deng
Abstract Background: Honokiol has been known to have antitumour activity. This study was conducted to evaluate the antiproliferative potential of honokiol against the hepG2 heptocellular cell line and its mechanism of action. Methods: hepG2 cells were treated with honokiol of 0,40 ,g/ml concentration. The cytotoxic effect of honokiol was determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The apoptosis was evaluated by flow cytometry. Western blots were used to analyse the expression of various proteins (procaspase-9, procaspase-3, cleaved caspase-3, cytochrome c, Bcl-2, Bax, Bad, Bcl-XL and p38). Results: Honokiol induced apoptosis with a decreased expression of procaspase-3 and -9 and an increased expression of active caspase-3. Exposure of hepG2 cells to honokiol resulted in the downregulation of Bcl-XL and Bcl-2 expression and the release of mitochondrial cytochrome c to the cytosol. In addition, honokiol activated the p38 mitogen-activated protein kinase (MAPK) pathway, and the inhibition of this pathway by SB203580 reduced honokiol-induced apoptosis and activation of caspase-3. Conclusion: Honokiol induces apoptosis of hepG2 human hepatocellular carcinoma cells through activation of the p38 MAPK pathway, and, in turn, activation of caspase-3. [source]

Interferon-, mediates suppression of C-reactive protein: Explanation for muted C-reactive protein response in lupus flares?

Helena Enocsson
Objective C-reactive protein (CRP) is synthesized by hepatocytes in response to interleukin-6 (IL-6) during inflammation. Despite raised IL-6 levels and extensive systemic inflammation, serum CRP levels remain low during most viral infections and disease flares of systemic lupus erythematosus (SLE). Because both viral infections and SLE are characterized by high levels of interferon-, (IFN,), the aim of this study was to determine whether this cytokine can inhibit the induction of CRP. Methods The interference of all 12 IFN, subtypes with CRP promoter activity induced by IL-6 and IL-1, was studied in a CRP promoter, and luciferase reporter,transfected human hepatoma cell line, Hep-G2. CRP secretion by primary human hepatocytes was analyzed by enzyme-linked immunosorbent assay. Results CRP promoter activity was inhibited by all single IFN, subtypes, as well as by 2 different mixtures of biologically relevant IFN, subtypes. The most prominent effect was seen using a leukocyte-produced mixture of IFN, (56% inhibition at 1,000 IU/ml). The inhibitory effect of IFN, was confirmed in primary human hepatocytes. CRP promoter inhibition was dose dependent and mediated via the type I IFN receptor. Transferrin production and Hep-G2 proliferation/viability were not affected by IFN,. Conclusion The current study demonstrates that IFN, is an inhibitor of CRP promoter activity and CRP secretion. This finding concords with previous observations of up-regulated IFN, and a muted CRP response during SLE disease flares. Given the fundamental role of both IFN, and CRP in the immune response, our results are of importance for understanding the pathogenesis of SLE and may also contribute to understanding the differences in the CRP response between viral and bacterial infections. [source]

Expression and role of Bcl-xL in human hepatocellular carcinomas

HEPATOLOGY, Issue 1 2001
Tetsuo Takehara
Transformed hepatocytes survive various apoptotic insults during their growth in vivo. However, molecular mechanisms that inhibit apoptosis and support their survival are not well understood. In this study, we investigated the expression and role of Bcl-xL, an antiapoptotic member of the Bcl-2 family, in human hepatocellular carcinoma (HCC). The Bcl-xL protein was expressed in HepG2, Hep3B, and Huh7 human hepatoma cell lines at high levels, but none of these cells expressed Bcl-2. Down-modulation of Bcl-xL by antisense oligonucleotide activated apoptosis in HepG2 cells in response to cellular stresses induced by staurosporine treatment or by serum starvation. Ectopic expression of transcriptionally active p53 alone was not sufficient for the activation of apoptosis in p53 -null Hep3B cells, but apoptosis was induced when endogenous Bcl-xL was simultaneously inhibited by antisense oligonucleotide in these cells. Bcl-xL was expressed in all 20 surgically resected human HCC tissues when examined by Western blot analysis and immunohistochemistry, and levels of its expression were higher in a subset of HCC tissues than those of adjacent nontumor liver tissues or normal livers. We conclude that Bcl-xL expressed in human HCC cells inhibits apoptosis produced by various cellular stresses, such as staurosporine treatment, serum starvation, and p53 activation, and may play an important role in their survival. [source]

Cytokines alter the expression and activity of the multidrug resistance transporters in human hepatoma cell lines; analysis using RT-PCR and cDNA microarrays

Gigi Lee
Abstract Pro-inflammatory cytokines suppress the hepatic expression of the multidrug resistance transporters in rodents, indicating potential usefulness in chemotherapy. Our objective was to investigate their impact in human hepatoma cells. HuH 7 and HepG2 cells were treated with IL-1,, IL-6, or TNF-, for 0,72 h. Expression and activity of MDR1 and the MRP (MRP1, 2, 3, and 6) transporters were examined by RT-PCR, efflux assays, and microarrays. Significant reductions in the MDR1-mediated efflux of Rhodamine 123 and MDR1 mRNA levels were observed in HuH 7 cells treated with IL-6, TNF-,, or IL-1, and in TNF-,,treated HepG2 cells. However, cytokine-treated HuH7 cells also demonstrated 1.6- to 2.6-fold greater efflux of the MRP substrate, 5-carboxyfluorescein (5-CF) and higher MRP3 mRNA levels (p,<,0.05). IL-1, and IL-6 treatments increased MRP activity and MRP1 mRNA levels in HepG2 cells (p,<,0.05). Microarrays studies performed in IL-6 and TNF-,,treated HepG2 cells detected similar changes in the expression of the MDR1 and MRP transporters, but this did not reach significance. However, the microarrays confirmed cytokine-mediated induction of several acute phase proteins. Our data suggests that although cytokine-mediated suppression of PGP may alter drug resistance in malignant cells, these cytokines may also impose an induction in other multidrug resistance genes. 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:2152,2163, 2003 [source]

Study of the effects of interferon a on several human hepatoma cell lines: analysis of the signalling pathway of the cytokine and of its effects on apoptosis and cell proliferation

A. Legrand
Background: Interferon , (IFN,), currently used for the treatment of chronic viral hepatitis, is also known to prevent the development of hepatocellular carcinoma (HCC), the mechanism of this action being still debatable. Aims: To study thoroughly in human hepatoma cell lines (HHL) , Hep3B, HepG2, HuH7, SKHep1, and Chang-Liver , submitted to rhIFN,, the signalling pathway of IFN,, the binding activity of the cytokine on specific gamma-activated sequence (GAS) and interferon-stimulated regulatory element (ISRE) nuclear sequences, and its effects on apoptosis and cell proliferation. Methods: The behaviour of signal transducer and activator of transcription (STAT)1, STAT2, p48IRF9 and the binding of nuclear proteins were investigated by immunoblot and electro-mobility shift assay. Expression of some IFN,-dependent proteins , p21/WAF1, inducible nitric oxide synthase, IRF1 and 2 , were studied by immunoblot. Apoptosis and the cell cycle were studied by morphological and biochemical methods. Results: Transduction of INF, was unaltered, although there were some variations in the different HHL. Nuclear protein binding to GAS or ISRE showed that ISRE was mainly involved. Apoptosis did not occur. The cell cycle was slightly modified in HuH7. Three GAS- and/or ISRE-dependent proteins increased, suggesting that IFN, may have some biological effects on HHL. Conclusions: The IFN, signalling pathway is functional in several HHL, but the cytokine has no apoptotic effect and a moderate anti-proliferative effect. This suggests that the preventive role of IFN, on HCC cannot be explained by an apoptotic and/or an anti-proliferative effect, but possibly by its action on several specific nuclear sequences that protect liver cells from transformation. [source]

Antioxidant and cytotoxic activities of Hypericum sp. on brine shrimps and human cancer cell lines

M. Couladis
Abstract Ten different samples of five Hypericum sp. were tested on brine shrimps, human colon carcinoma and human hepatoma cell lines for their cytotoxic activities. H. triquetrifolium Turra. (Rafina) showed the highest activity (LC50,=,22,mg/mL) on brine shrimps, while the extracts of the other nine samples showed significant to moderate activities (LC50 from 37 to 107,mg/mL). H. empetrifolium Wild. (Parnon) showed the highest activity in human colon carcinoma and human hepatoma cell lines, with LC50 values 29 and 25.1,mg/mL, respectively, while the LC50 values of the other samples were more than 45,mg/mL. It is very interesting to observe that most Hypericum samples showed good antioxidant activity in vitro. Copyright 2002 John Wiley & Sons, Ltd. [source]