Human Hepatoma HepG2 Cells (human + hepatoma_hepg2_cell)

Distribution by Scientific Domains

Selected Abstracts

Electrophoretic behaviors of human hepatoma HepG2 cells

Jyh-Ping Hsu
Abstract The electrophoretic mobility of HepG2 cells was measured and a charge-regulated model was proposed to simulate the results obtained. Here, a cell was simulated by a rigid core and an ion-penetrable membrane layer containing both acidic and basic functional groups. The influences of the key parameters, including the pH, the ionic strength, the thickness of the membrane layer of a cell, the density and the dissociation constant of the dissociable functional groups in the membrane layer, and the binding constant of divalent cations on the electrophoretic mobility of a cell were investigated. In particular, the role of the buffer used in the experiment was discussed; this effect was neglected in almost all the relevant theoretical analyses in the literature. We showed that the binding ability of divalent cations to the dissociated functional groups in the membrane layer of a cell ranks as Ca2+>Mg2+>hexamethonium. [source]

The PPAR, agonist GW501516 suppresses interleukin-6-mediated hepatocyte acute phase reaction via STAT3 inhibition

T. Kino
Abstract Background, Interleukin-6 and downstream liver effectors acute phase reactants are implicated in the systemic inflammatory reaction. Peroxisome proliferator-activated receptor , (PPAR,), which binds to and is activated by a variety of fatty acids, was recently shown to have anti-inflammatory actions. Materials and methods, We examined the ability of the synthetic PPAR, agonist GW501516 to suppress interleukin-6-induced expression of acute phase proteins in human hepatoma HepG2 cells and rat primary hepatocytes. Results, GW501516 dose-dependently suppressed interleukin-6-induced mRNA expression of the acute phase protein ,1-antichymotrypsin in HepG2 cells. The compound also suppressed interleukin-6-induced mRNA expression of ,2-acid glycoprotein, ,-fibrinogen and ,2-macroglobulin in and the secretion of C-reactive protein by rat primary hepatocytes. Depletion of the PPAR, receptor, but not of PPAR, or ,, attenuated the suppressive effect of GW501516 on interleukin-6-induced ,1-antichymotrypsin mRNA expression, indicating that PPAR, specifically mediated this effect. Since interleukin-6 stimulates the transcriptional activity of the ,1-antichymotrypsin promoter by activating the signal transducer and activator of transcription (STAT) 3, we examined functional interaction of this transcription factor and PPAR, on this promoter. Overexpression of PPAR, enhanced the suppressive effect of GW501516 on STAT3-activated transcriptional activity of the ,1-antichymotrypsin promoter, while GW501516 suppressed interleukin-6-induced binding of this transcription factor to this promoter. Conclusions, These findings indicate that agonist-activated PPAR, interferes with interleukin-6-induced acute phase reaction in the liver by inhibiting the transcriptional activity of STAT3. PPAR, agonists might be useful for the suppression of systemic inflammatory reactions in which IL-6 plays a central role. [source]

Triterpenoid Ester Saponins from Dipteronia dyeriana

Rong Guo
Abstract The phytochemical investigation of Dipteronia dyeriana (Aceraceae) resulted in the isolation and identification of five new triterpenoid ester saponins, dipterosides A,E (1,5). Their structures were elucidated by spectroscopic methods and chemical evidence. The inhibitory activities of these compounds against human leukemia K562 and human hepatoma HepG2 cells were also evaluated. [source]

Real time monitoring of drug metabolic enzyme response inside human hepatoma GS-3A4-HepG2 cells by means of electrochemical impedance measurement

Masaaki Kobayashi
Abstract Cytochrome P-450s (CYPs) are important biopolymers for the maintenance of cellular function. If metabolic activity of the CYP in the cells can be estimated, so can the function of metabolism, which is closer to the organism. In this research, the method of measuring the drug metabolic activity inside the cell by making use of an electrochemical technique was examined. Human hepatoma GS-3A4-HepG2 cells of which the cytochrome P-4503A4 (CYP3A4) drug metabolic activity is found to be the same as that of primary hepatocytes were used in the experiment. The GS-3A4-HepG2 cells were cultured on an indium-tin oxide (ITO) electrode until they became confluent. Substrate testosterone and inhibitor ketoconazole of CYP3A4 were exposed to cells cultured on an ITO electrode, and the reaction was observed by noting the electrochemical impedance measurement. Impedance was decomposed into the resistance component and the reactance component, and each was examined in detail. As a result, according to testosterone concentration change, there was a remarkable time change in the reactance component. A similar impedance measurement was done by using human hepatoma HepG2 cells in which the drug metabolic activity had extremely decreased. Nevertheless, no time change in the reactance component that was noticed in GS-3A4-HepG2 cells was observed. Next, the amount of metabolite in the solution after impedance measurement was measured by means of liquid chromatography-tandem mass spectroscopy (LC-MS/MS). In the experiment with GS-3A4-HepG2 cells, a testosterone concentration-dependent correlation was observed between the reactance component change and the amount of metabolite. But, in the impedance measurement by ketoconazole, the change in reactance components was not observed in either the GS-3A4-HepG2 cells or the HepG2 cells. Ketoconazole and the heme iron in CYP3A4 effect the coordination bond, but ketoconazole was not metabolized by CYP3A4. It was confirmed that the time change in the reactance component which was caused by the testosterone was detected neither in the cells that take up the substrate, nor in the coordination bond between the CYP enzyme and the drug. Therefore, the time change in the remarkable reactance component observed by this electrochemical impedance measurement is dependent on drug metabolic activity. An electrochemical drug metabolic activity measuring method with the human hepatoma GS-3A4-HepG2 cells was able to be established. Copyright 2004 John Wiley & Sons, Ltd. [source]

Strategic shotgun proteomics approach for efficient construction of an expression map of targeted protein families in hepatoma cell lines

Chih-Lei Lee
Abstract An expression map of the most abundant proteins in human hepatoma HepG2 cells was established by a combination of complementary shotgun proteomics approaches. Two-dimensional liquid chromatography (LC)-nano electrospray ionization (ESI) tandem mass spectrometry (MS/MS) as well as one-dimensional LC-matrix-assisted laser desorption/ionization MS/MS were evaluated and shown that additional separation introduced at the peptide level was not as efficient as simple prefractionation of protein extracts in extending the range and total number of proteins identified. Direct LC-nanoESI MS/MS analyses of peptides from total solubilized fraction and the excised gel bands from one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis fractionated insolubilized fraction afforded the best combination in efficient construction of a nonredundant cell map. Compiling data from multiple variations of rapid shotgun proteomics analyses is nonetheless useful to increase sequence coverage and confidence of hits especially for those proteins identified primarily by a single or two peptide matches. While the returned hit score in general reflects the abundance of the respective proteins, it is not a reliable index for differential expression. Using another closely related hepatoma Hep3B as a comparative basis, 16 proteins with more than two-fold difference in expression level as defined by spot intensity in two-dimensional gel electrophoresis analysis were identified which notably include members of the heat shock protein (Hsp) and heterogeneous nuclear ribonucleoprotein (hnRPN) families. The observed higher expression level of hnRNP A2/B1 and Hsp90 in Hep3B led to a search for reported functional roles mediated in concert by both these multifunctional cellular chaperones. In agreement with the proposed model for telomerase and telomere bound proteins in promoting their interactions, data was obtained which demonstrated that the expression proteomics data could be correlated with longer telomeric length in tumorigenic Hep3B. This biological significance constitutes the basis for further delineation of the dynamic interactions and modifications of the two protein families and demonstrated how proteomic and biological investigation could be mutually substantiated in a productive cycle of hypothesis and pattern driven research. [source]

Biological effects of a nano red elemental selenium

BIOFACTORS, Issue 1 2001
Jin-Song Zhang
A novel selenium form, nano red elemental selenium (Nano-Se) was prepared by adding bovine serum albumin to the redox system of selenite and glutathione. Nano-Se has a 7-fold lower acute toxicity than sodium selenite in mice (LD50 113 and 15 mg Se/kg body weight respectively). In Se-deficient rat, both Nano-Se and selenite can increase tissue selenium and GPx activity. The biological activities of Nano-Se and selenite were compared in terms of cell proliferation, enzyme induction and protection against free racial-mediated damage in human hepatoma HepG2 cells. Nano-Se and selenite are similarly cell growth inhibited and stimulated synthesis of glutathione peroxidase (GPx), phospholipid hydroperoxide glutathione peroxidase (PHGPx) and thioredoxin reductase (TR). When HepG2 cells were co-treated with selenium and glutathione, Nano-Se showed less pro-oxidative effects than selenite, as measured by cell growth. These results demonstrate that Nano-Se has a similar bioavailability in the rat and antioxidant effects on cells. [source]