scholarly journals Chemoprotective activity of the isoflavones, genistein and daidzein on mutagenicity induced by direct and indirect mutagens in cultured HTC cells

2012 ◽  
Vol 65 (2) ◽  
pp. 213-222 ◽  
Author(s):  
Sandra Regina Lepri ◽  
Rodrigo Cabral Luiz ◽  
Leonardo Campos Zanelatto ◽  
Patrícia Benites Gonçalves da Silva ◽  
Daniele Sartori ◽  
...  
Keyword(s):  
Htc Cells

Analysis of the induction and deinduction of tyrosine aminotransferase in enucleated HTC cells

1975 ◽  
Vol 85 (S1) ◽  
pp. 357-364 ◽  
Author(s):  
R. D. Ivarie ◽  
W. J.-W. Fan ◽  
G. M. Tomkins
Keyword(s):  
Tyrosine Aminotransferase ◽  
Htc Cells

Hyperthermic cell death of HTC cells in culture: a comparison of assays

1989 ◽  
Vol 17 (3) ◽  
pp. 531-532
Author(s):  
CATHARINE A. KINGSTON ◽  
SHABIRALI LADHA ◽  
RAY MANNING ◽  
KEN BOWLER
Keyword(s):  
Cell Death ◽  
Cells In Culture ◽  
Htc Cells

scholarly journals Sendai-viral HN and F glycoproteins as probes of plasma-membrane protein catabolism in HTC cells. Studies with fusogenic reconstituted Sendai-viral envelopes

1987 ◽  
Vol 241 (3) ◽  
pp. 801-807 ◽  
Author(s):  
R T Earl ◽  
E E Billett ◽  
I M Hunneyball ◽  
R J Mayer
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Plasma Membranes ◽  
Viral Proteins ◽  
Plasma Membrane Protein ◽  
Lysosomal Degradation ◽  
Cell Plasma ◽  
Degradation Rates ◽  
Htc Cells ◽  
Viral Envelopes

Reconstituted Sendai-viral envelopes (RSVE) were produced by the method of Vainstein, Hershkovitz, Israel & Loyter [(1984) Biochim. Biophys. Acta 773, 181-188]. RSVE are fusogenic unilamellar vesicles containing two transmembrane glycoproteins: the HN (haemagglutinin-neuraminidase) protein and the F (fusion) factor. The fate of the viral proteins after fusion-mediated transplantation of RSVE into hepatoma (HTC) cell plasma membranes was studied to probe plasma-membrane protein degradation. Both protein species are degraded at similar, relatively slow, rates (t1/2 = 67 h) in HTC cells fused with RSVE in suspension. Even slower degradation rates for HN and F proteins (t1/2 = 93 h) were measured when RSVE were fused with HTC cells in monolayer. Lysosomal degradation of the transplanted viral proteins is strongly implicated by the finding that degradation of HN and F proteins is sensitive to inhibition by 10 mM-NH4Cl (81%) and by 50 micrograms of leupeptin/ml (70%).

scholarly journals Effects of cross-linked dimers of ribonuclease A or of lysozyme on the processing of endocytosed peroxidase by hepatoma cells

1982 ◽  
Vol 202 (2) ◽  
pp. 543-550
Author(s):  
J Bartholeyns ◽  
P Baudhuin
Keyword(s):  
Mechanism Of Action ◽  
Binding Sites ◽  
Culture Medium ◽  
Basic Protein ◽  
Intracellular Localization ◽  
Ribonuclease A ◽  
Protein Processing ◽  
Intracellular Protein ◽  
Intracellular Degradation ◽  
Htc Cells

Cross-linked dimers of ribonuclease, added at a concentration of 0.05 mg/ml to the culture medium of hepatoma (HTC) cells, were previously shown to inhibit intracellular degradation of peroxidase taken up by endocytosis. Intracellular localization showed that endocytosed peroxidase does not reach lysosomes in dimer-treated cells. The present study shows that preloading of lysosomes with fluorescent anti-peroxidase IgG, obtained by exposing HTC cells for 48 h to 0.1 mg of antibody/ml, restores intracellular degradation of endocytosed peroxidase. Moreover, accumulation of peroxidase into lysosomes, which no longer occurs in dimer-treated cells, occurs again under these conditions. We conclude that inhibition of transfer of peroxidase from phagosomes to lysosomes is most likely to be the alteration resulting from the exposure of the cells to ribonuclease dimer, rather than inhibition of fusion between phagosomes and lysosomes. The dimer of another basic protein, lysozyme added at a concentration of 0.2 mg/ml to the culture medium, is shown to induce the same type of effects as does the dimer of ribonuclease; the half-life of endocytosed peroxidase increased from 5 to 15 h after 2 h exposure of HTC cells to dimerized lysozyme. The effect of both dimers on intracellular protein processing can be reversed by addition of 100 mm-galactose to the culture medium, up to 5 h after pretreatment of the cells. The dimers of ribonuclease A or of lysozyme have thus probably the same mechanism of action. Evidence that the two dimers share the same binding sites on the cells is presented.

Nucleotide receptors activate cation, potassium, and chloride currents in a liver cell line

1994 ◽  
Vol 266 (4) ◽  
pp. G544-G553 ◽  
Author(s):  
J. G. Fitz ◽  
A. H. Sostman
Keyword(s):  
Nucleotide Receptors ◽  
Chloride Currents ◽  
Whole Cell Patch Clamp ◽  
Current Voltage ◽  
Htc Cells ◽  
Sequential Activation ◽  
Initial Activation ◽  
K Permeability ◽  
Current Voltage Relation ◽  
Sustained Activation

By use of whole cell patch-clamp techniques, the effects of extracellular ATP on membrane ion currents of HTC cells from a rat liver tumor line were evaluated. ATP (500 microM) or the nonhydrolyzable analogue adenosine 5'-O-(3-thiotriphosphate) caused sequential activation of three currents: Icat (-1,325 +/- 255 pA at -80 mV) occurred early, was due to increased Na+ and K+ permeability, was present in 56% of 64 consecutive cells, and rapidly inactivated; IK (274 +/- 45 pA at 0 mV) was present in 59% of cells and also inactivated; and ICl (1,172 +/- 237 pA at +60 mV) was present in 94% of studies, was sustained, and exhibited outward rectification of the current-voltage relation. All three currents were present in 39% of cells. Increasing intracellular Ca2+ concentration ([Ca2+]i) by exposure to the 5'-nucleotide receptor agonist UTP (500 microM) or to thapsigargin activated Icat and IK but not ICl, whereas increasing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid in the pipette (> or = 5 mM) inhibited ATP-dependent activation of Icat and IK but not ICl. A P2x-preferring agonist alpha, beta-methylene ATP (500 microM) did not activate currents; a P2y-preferring agonist 2-methylthioadenosine triphosphate activated Icat and IK at concentrations of 500 microM but not 50 microM. In perforated patch recordings, ATP produced triphasic changes in membrane potential with initial depolarization due to Icat, subsequent hyperpolarization due to IK, and a later sustained depolarization due to ICl. These findings indicate that ATP modulates HTC cell ion permeability through initial activation of Icat and IK mediated by 5'-nucleotide receptors which mobilize [Ca2+], and sustained activation of ICl through a separate Ca(2+)-independent mechanism.

scholarly journals Antizyme induction by polyamine analogues as a factor of cell growth inhibition

2002 ◽  
Vol 366 (2) ◽  
pp. 663-671 ◽  
Author(s):  
John L.A. MITCHELL ◽  
Aviva LEYSER ◽  
Michelle S. HOLTORFF ◽  
Jill S. BATES ◽  
Benjamin FRYDMAN ◽  
...  
Keyword(s):  
Cell Growth ◽  
Growth Inhibition ◽  
Feedback Inhibition ◽  
Conformationally Constrained ◽  
Polyamine Analogues ◽  
Polyamine Transport ◽  
Mammalian Cell Growth ◽  
Htc Cells ◽  
Cell Growth And Viability ◽  
Selection Of

The polyamines spermidine and spermine and their diamine precursor putrescine are essential for mammalian cell growth and viability, and strategies are sought for reducing polyamine levels in order to inhibit cancer growth. Several structural analogues of the polyamines have been found to decrease natural polyamine levels and inhibit cell growth, probably by stimulating normal feedback mechanisms. In the present study, a large selection of spermine analogues has been tested for their effectiveness in inducing the production of antizyme, a key protein in feedback inhibition of putrescine synthesis and cellular polyamine uptake. Bisethylnorspermine, bisethylhomospermine, 1,19-bis-(ethylamino)-5,10,15-triazanonadecane, longer oligoamine constructs and many conformationally constrained analogues of these compounds were found to stimulate antizyme synthesis to different levels in rat liver HTC cells, with some producing far more antizyme than the natural polyamine spermine. Uptake of the tested compounds was found to be dependent on, and limited by, the polyamine transport system, for which all these have approximately equal affinity. These analogues differed in their ability to inhibit HTC cell growth during 3days of exposure, and this ability correlated with their antizyme-inducing potential. This is the first direct evidence that antizyme is induced by several polyamine analogues. Selection of analogues with this potential may be an effective strategy for maximizing polyamine deprivation and growth inhibition.

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