scholarly journals Glutathione transferases in rat hepatoma cells. Effects of ascites cells on the isoenzyme pattern in liver and induction of glutathione transferases in the tumour cells

1989 ◽  
Vol 257 (1) ◽  
pp. 215-220 ◽  
Author(s):  
M K Tahir ◽  
C Guthenberg ◽  
B Mannervik
Keyword(s):  
Glutathione Transferase ◽  
Hepatoma Cell ◽  
Normal Liver ◽  
Hepatoma Cells ◽  
Glutathione Transferases ◽  
Trans Stilbene ◽  
Cytosolic Glutathione ◽  
Fold Induction ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

Rat hepatoma cells grown intraperitoneally as an ascites tumour were analysed with respect to their contents of cytosolic glutathione transferases. In contrast with normal liver tissue, the hepatoma cells were dominated by the class Pi glutathione transferase 7-7. All the major hepatic enzyme forms were down-regulated to almost undetectable concentrations. Livers of rats bearing ascites-hepatoma cells expressed low, but significant, amounts of protein which, by electrophoretic and immunochemical properties, appeared identical with transferase 7-7. This enzyme is not detectable in normal hepatocytes. Treatment of rats with trans-stilbene oxide induced the expression of transferase 7-7 in the livers of normal rats as well as in hepatoma-cell-bearing animals. In addition, a 2-fold induction of transferase 7-7 was measured in the hepatoma ascites cells. No significant elevation of any other enzyme forms in the hepatoma cells was noted.

Increase in class 2 aldehyde dehydrogenase expression by arachidonic acid in rat hepatoma cells

2001 ◽  
Vol 357 (3) ◽  
pp. 811-818 ◽  
Author(s):  
Rosa A. CANUTO ◽  
Margherita FERRO ◽  
Raffaella A. SALVO ◽  
Anna M. BASSI ◽  
Antonella TROMBETTA ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Arachidonic Acid ◽  
Cell Growth ◽  
Cell Lines ◽  
Aldehyde Dehydrogenase ◽  
Hepatoma Cell ◽  
Hepatoma Cells ◽  
Hepatoma Cell Lines ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

Aldehyde dehydrogenase (ALDH) is a family of several isoenzymes important in cell defence against both exogenous and endogenous aldehydes. Compared with normal hepatocytes, in rat hepatoma cells the following changes in the expression of ALDH occur: cytosolic class 3 ALDH expression appears and mitochondrial class 2 ALDH decreases. In parallel with these changes, a decrease in the polyunsaturated fatty acid content in membrane phospholipids occurs. In the present study we demonstrated that restoring the levels of arachidonic acid in 7777 and JM2 rat hepatoma cell lines to those seen in hepatocytes decreases hepatoma cell growth, and increases class 2 ALDH activity. This latter effect appears to be due to an increased gene transcription of class 2 ALDH. To account for this increase, we examined whether peroxisome-proliferator-activated receptors (PPARs) or lipid peroxidation were involved. We demonstrated a stimulation of PPAR expression, which is different in the two hepatoma cell lines: in the 7777 cell line, there was an increase in PPARα expression, whereas PPARγ expression increased in JM2 cells. We also found increased lipid peroxidation, but this increase became evident at a later stage when class 2 ALDH expression had already increased. In conclusion, arachidonic acid added to the culture medium of hepatoma cell lines is able to partially restore the normal phenotype of class 2 ALDH, in addition to a decrease in cell growth.

scholarly journals Glucocorticoid-stimulated CCAAT/enhancer-binding protein alpha expression is required for steroid-induced G1 cell cycle arrest of minimal-deviation rat hepatoma cells.

1996 ◽  
Vol 16 (10) ◽  
pp. 5288-5301 ◽  
Author(s):  
R A Ramos ◽  
Y Nishio ◽  
A C Maiyar ◽  
K E Simon ◽  
C C Ridder ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Cell Cycle Arrest ◽  
Hepatoma Cell ◽  
Hepatoma Cells ◽  
Cycle Arrest ◽  
Minimal Deviation ◽  
G1 Cell Cycle Arrest ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

By genetic correlation with the growth-suppressible phenotype and direct functional tests, we demonstrate that the glucocorticoid-stimulated expression of the CCAAT/enhancer-binding protein alpha (C/EBP alpha) transcription factor is required for the steroid-mediated G1 cell cycle arrest of minimal-deviation rat hepatoma cells. Comparison of C/EBP alpha transcript and active protein levels induced by the synthetic glucocorticoid dexamethasone in glucocorticoid growth-suppressible (BDS1), nonsuppressible receptor-positive (EDR1) and nonsuppressible receptor-deficient (EDR3) hepatoma cell proliferative variants revealed that the stimulation of C/EBP alpha expression is a rapid, glucocorticoid receptor-mediated response associated with the G1 cell cycle arrest. Consistent with the role of C/EBP alpha as a critical intermediate in the growth suppression response, maximal induction of transcription factor mRNA occurred within 2 h of dexamethasone treatment whereas maximal inhibition of [3H] thymidine incorporation was observed 24 h after steroid treatment. As a direct functional approach, ablation of C/EBP alpha protein expression and DNA-binding activity by transfection of an antisense C/EBP alpha expression vector blocked the dexamethasone-induced G1 cell cycle arrest of hepatoma cells but did not alter general glucocorticoid responsiveness. Transforming growth factor beta induced a G1 cell cycle arrest in C/EBP alpha antisense transfected cells, demonstrating the specific involvement of C/EBP alpha in the glucocorticoid growth suppression response. Constitutive expression of a conditionally activated form of C/EBP alpha caused a G1 cell cycle arrest of BDS1 hepatoma cells in the absence of glucocorticoids. In contrast, overexpression of C/EBP beta or C/EBP delta had no effect on hepatoma cell growth. Taken together, these results demonstrate that the steroid-induced expression of C/EBP alpha is necessary to mediate the glucocorticoid G1 cell cycle arrest of rat hepatoma cells and implicates a role for this transcription factor in the growth control of liver-derived epithelial tumor cells.

scholarly journals Rat hepatoma cells express novel transport systems for glutamine and glutamate in addition to those present in normal rat hepatocytes

1998 ◽  
Vol 330 (1) ◽  
pp. 255-260 ◽  
Author(s):  
D. John MGIVAN
Keyword(s):  
Cell Line ◽  
Transport System ◽  
Hepatoma Cell ◽  
Rat Hepatocytes ◽  
Hepatoma Cells ◽  
Transport Systems ◽  
Hepatoma Cell Line ◽  
High Affinity ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

The rat hepatoma cell line H4-II-E was found to express much higher activities of Na+-dependent glutamine and aspartate transport than those observed in normal cultured hepatocytes, in agreement with previous work of others on human hepatocytes. Na+-dependent glutamine transport in rat hepatoma cells could be resolved into two components. One was pH-dependent, tolerated Li+ for Na+ substitution and was inhibited only by asparagine and histidine; characteristics similar to those of transport System N in hepatocytes. The other transport system had a similar Km for glutamine but was pH independent, did not accept Li+ ions and was completely inhibited by excess concentrations of lysine, histidine, leucine, serine and cysteine, but not by methyl-aminoisobutyrate or phenylalanine. This pattern of inhibition is distinct from that of any transporter occurring in normal hepatocytes and may indicate the presence of a new transporter isoform. Similar results were obtained with the cell line HTC. Na+-dependent aspartate transport in H4 hepatoma cells was mediated by a high-affinity system (Km 5 μM) and was inhibited by D-aspartate and L-glutamate but not by D-glutamate - properties characteristic of the high-affinity glutamate transporter EAAC1. C-terminal antibodies to the EAAC1 protein recognized a single band of 58 kDa in hepatocyte membranes, but an additional strong band of 60 kDa was present in H4 hepatoma cells. These results provide further evidence for the view that tumour cells may express additional isoforms of amino acid transport systems which are not present in non-transformed cells.

scholarly journals Effects of inducers of drug metabolism on basic hepatic forms of mouse glutathione transferase

1989 ◽  
Vol 263 (3) ◽  
pp. 679-685 ◽  
Author(s):  
P Di Simplicio ◽  
H Jensson ◽  
B Mannervik
Keyword(s):  
Mouse Liver ◽  
Glutathione Transferase ◽  
Major Effect ◽  
Glutathione Transferases ◽  
Control Group ◽  
Glyoxalase I ◽  
Protein Profiles ◽  
Trans Stilbene ◽  
Cytosolic Glutathione ◽  
Gst Activity

The cytosolic glutathione transferases (GSTs) with basic pI values have been studied in mouse liver after treatment with 2,3-t-butylhydroxyanisole (BHA), cafestol palmitate (CAF), phenobarbital (PB), 3-methylcholanthrene (3-MC) and trans-stilbene oxide (t-SBO). The cytosolic GST activity was induced by all compounds except for 3-MC. Three forms of GST were isolated by means of affinity chromatography and f.p.l.c. The examination of protein profiles and enzymic activities with specific substrates showed that the three GSTs correspond to those found in control animals, i.e. GSTs MI, MII and MIII. The class Mu GST MIII accounted for the major effect of induction, whereas the class Alpha GST MI and the class Pi GST MII were unchanged or somewhat down-regulated. The greatest induction was obtained with BHA, PB and CAF. The activities of other glutathione-dependent enzymes were also studied. An increase in glutathione reductase and thioltransferase activities was observed after BHA, PB or CAF treatment; glyoxalase I and Se-dependent glutathione peroxidase were depressed in comparison with the control group in all cases studied.

scholarly journals Identification of the insulin receptor tyrosine residues undergoing insulin-stimulated phosphorylation in intact rat hepatoma cells.

1988 ◽  
Vol 263 (1) ◽  
pp. 350-359 ◽  
Author(s):  
H E Tornqvist ◽  
J R Gunsalus ◽  
R A Nemenoff ◽  
A R Frackelton ◽  
M W Pierce ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Hepatoma Cells ◽  
Tyrosine Residues ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells
Sign in / Sign up

Export Citation Format

Share Document