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Title
Role of antioxidant enzymes in the induction of increased experimental
metastasis by hydroxyurea.
Author
Eskenazi AE; Pinkas J; Whitin JC; Arguello F; Cohen HJ; Frantz
CN
Address
Department of Pediatrics, University of Maryland School of Medicine,
Baltimore.
Source
J Natl Cancer Inst, 85(9):711-21 1993 May 5
Abstract
BACKGROUND: Treatment of tumor cells with hydroxyurea and other
DNA-damaging agents has been shown to increase the experimental
metastatic potential of these cells. PURPOSE: We sought to elucidate
some of the biochemical and genetic changes that promote tumor
cell
metastasis in hydroxyurea-treated cells. We hypothesized that
drug
treatment induces resistance to oxidative damage and that elimination
of this resistance reverses the drug-induced experimental metastatic
capabilities of tumor cells. METHODS: We examined the effect
of
hydroxyurea treatment on B16 melanoma cells with respect to
experimental metastatic potential, resistance to hydrogen peroxide
(H2O2), glutathione peroxidase activity and messenger RNA (mRNA)
level,
glutathione reductase activity, glutathione levels,
glutathione-S-transferase activity, and catalase activity and
mRNA
level. RESULTS: Hydroxyurea-treated cells were transiently more
metastatic following intravenous injection in syngeneic mice
and
transiently more resistant than untreated cells to exogenous
H2O2.
Hydroxyurea-induced experimental metastases and H2O2 resistance
were
eliminated by depletion of intracellular glutathione with buthionine
sulfoximine. glutathione peroxidase activity and mRNA level,
glutathione reductase activity, and reduced glutathione levels
were all
transiently increased in hydroxyurea-treated cells, whereas the
increase in glutathione-S-transferase activity was sustained.
Catalase
activity was modestly increased with no increase in its mRNA
levels.
CONCLUSIONS: In B16 melanoma cells, experimental metastasis induced
by
hydroxyurea appears to depend on a process that requires glutathione.
Hydroxyurea treatment also induces resistance to exogenous H2O2,
which
may be due to induction of glutathione and antioxidant enzyme
activity.
IMPLICATIONS: The role of antioxidants in B16 melanoma cells
offers new
insights into the metastatic process and the cellular response
to
chemotherapy.
Title
glutathione-related enzymes, glutathione and multidrug resistance.
Author
Moscow JA; Dixon KH
Address
Medicine Branch, National Cancer Institute, Bethesda, MD 20892.
Source
Cytotechnology, 12(1-3):155-70 1993
Abstract
This review examines the hypothesis that glutathione and its
associated
enzymes contribute to the overall drug-resistance seen in multidrug
resistant cell lines. Reports of 34 cell lines independently
selected
for resistance to MDR drugs are compared for evidence of consistent
changes in activity of glutathione-related enzymes as well as
for
changes in glutathione content. The role of glutathione S-transferases
in MDR is further analyzed by comparing changes in sensitivity
to MDR
drugs in cell lines selected for resistance to non-MDR drugs
that have
resulting increases in glutathione S-transferase activity. In
addition,
results of studies in which genes for glutathione S-transferase
isozymes were transfected into drug-sensitive cells are reviewed.
The
role of the glutathione redox cycle is examined by comparing
changes in
elements of this cycle in MDR cell lines as well as by analyzing
reports of the effects of glutathione depletion on MDR drug
sensitivity. Overall, there is no consistent or compelling evidence
that glutathione and its associated enzymes augment resistance
in
multidrug resistant cell lines.
Title
Cytostatic drug resistance: parallel assessment of glutathione-based
detoxifying enzymes, O6-alkylguanine-DNA-alkyltransferase and
P-glycoprotein in adult patients with leukaemia.
Author
Joncourt F; Oberli A; Redmond SM; Fey MF; Tobler A; Margison
GP;
Gratwohl A; Buser K; Cerny T
Address
University of Berne, Department for Clinical-Experimental Research,
Switzerland.
Source
Br J Haematol, 85(1):103-11 1993 Sep
Abstract
The levels of several potential indicators of resistance to cytostatic
drugs were measured in leukaemic cells of a total of 64 adult
patients
with acute or chronic leukaemias before and during treatment
and at
relapse or recurrence of disease and compared with those of mononuclear
cells from the bone marrow of healthy donors. The resistance
factors
included glutathione (GSH) and its associated enzymes
glutathione-S-transferase (GST) and glutathione peroxidase (GPx)
as
well as O6-alkyguanine-DNA-alkyltransferase (ATase) and P-glycoprotein.
Median values for most parameters were significantly higher in
leukaemic cells than in those of normal donors although wide
interindividual variation in the values of the various parameters,
particularly GST, were seen. P-glycoprotein was measurable in
12.5% of
untreated leukaemias but in none of the normal donors. The values
of
the parameters in untreated leukaemic patients were not statistically
different from those at relapse or during disease progression.
However,
the median values for GSH, GST and GPx but not ATase in samples
from
untreated patients were significantly higher than those in samples
taken during drug treatment. Patient response, disease-free survival
or
duration of remission did not correlate with the values of any
of the
parameters studied.
Title
Do glutathione and related enzymes play a role in drug resistance
in
small cell lung cancer cell lines?
Author
Campling BG; Baer K; Baker HM; Lam YM; Cole SP
Address
Cancer Research Laboratories, Queen's University, Kingston, Canada.
Source
Br J Cancer, 68(2):327-35 1993 Aug
Abstract
Small cell lung cancer (SCLC) is treated primarily with combination
chemotherapy. Despite high initial response rates, most patients
eventually die with drug resistant disease. In some tumours,
resistance
to multiple chemotherapeutic agents is attributed to overexpression
of
P-glycoprotein (P-gp). However, this does not appear to be a
frequent
occurrence in drug resistant SCLC. Increased levels of glutathione
(GSH) and related enzymes may play a role in resistance to alkylating
agents as well as natural product drugs. We measured levels of
GSH,
glutathione S-transferase (GST), glutathione reductase (GSH Red),
glutathione peroxidase (GSH Px), and gamma-glutamyl transpeptidase
(gamma-GT) in a panel of 20 SCLC cell lines. Most of these lines
were
established from patients treated at this centre. Each cell line
had a
characteristic and reproducible profile of GSH and related enzyme
levels. Immunoblot analysis indicated that the predominant GST
in the
cell lines was the anionic pi isoenzyme. The relative sensitivity
of
each of these cell lines to 16 different chemotherapeutic agents
was
measured using a modified MTT assay. Spearman rank correlation
analysis
was used to determine the relationships between the relative
chemosensitivity of these cell lines and the levels of GSH and
related
enzymes. The number of positive correlations was no greater than
expected by chance alone. Furthermore, there was no correlation
with
the treatment history of the patients from whom the cell lines
were
derived. These data suggest that alterations in glutathione metabolism
do not play a major role in resistance to chemotherapeutic agents
in
these human SCLC cell lines.
Title
Activity loss of glutathione synthesis enzymes associated with
human
subcapsular cataract.
Author
Rathbun WB; Schmidt AJ; Holleschau AM
Address
Ophthalmology Department, University of Minnesota, Minneapolis
55455.
Source
Invest Ophthalmol Vis Sci, 34(6):2049-54 1993 May
Abstract
PURPOSE. To assess the activities of the two enzymes required
for
glutathione synthesis, gamma-glutamylcysteine synthetase and
glutathione synthetase, in various forms of human cataracts.
METHODS.
The Cooperative Cataract Research Group cataract classification
method
and standard enzyme assay procedures were used. RESULTS. An inverse
relationship was shown between residual activity of each of the
glutathione synthesis enzymes and degree of subcapsular cataract.
A
weaker inverse relationship existed between glutathione synthetase
activity and supranuclear and nuclear cataracts. No other parameters
yielded comparable correlations with the activity of either enzyme.
CONCLUSIONS. Activity loss of the glutathione synthesis enzymes
is
associated with human subcapsular cataract formation.
Title
glutathione-conjugate transport by human colon adenocarcinoma
cells
(Caco-2 cells).
Author
Oude Elferink RP; Bakker CT; Jansen PL
Address
Department of Gastrointestinal Diseases, Academic Medical Center,
Amsterdam, The Netherlands.
Source
Biochem J, 290 ( Pt 3)():759-64 1993 Mar 15
Abstract
The secretion of a glutathione-S-conjugate, dinitrophenyl-glutathione
(GS-DNP) was studied in the Caco-2 cells, a cultured human colonic
adenocarcinoma cell line with many of the characteristics of
enterocytes. The labelled glutathione conjugate was generated
within
the cell by incubation with 14C-labelled 1-chloro-2,4-dinitrobenzene
(CDNB). This compound is hydrophobic and enters the cell by simple
diffusion. Cells incubated with CDNB at 10 degrees C form only
one
metabolite, GS-DNP. After secretion into the medium GS-DNP is
partly
converted into one or two slightly more hydrophobic products.
This must
represent hydrolysis of the glutathione moiety by the action
of
gamma-glutamyltransferase (EC 2.3.2.2.; gamma-GT) because the
reaction
was completely inhibited by acivicin, an inhibitor of gamma-GT.
Secretion of GS-DNP was a temperature-sensitive, saturable process
with
an apparent Km of 1.03 +/- 0.26 nmol/mg of protein and a Vmax
of 111
+/- 17 pmol/min per mg of protein. The secretion was not sensitive
to
trans-stimulation by extracellular concentrations of GS-DNP up
to 2.5
mM. Furthermore the initial GS-DNP secretion rate was sensitive
to
dissipation of the membrane potential and correlated closely
with the
cellular ATP content. Caco-2 cells cultured on nitrocellulose
filters
secreted GS-DNP significantly faster over the basolateral membrane
than
over the apical membrane (146 +/- 25 versus 90 +/- 18 pmol/min
per mg
respectively). Secretion over both membrane domains of the cell
was
sensitive to ATP depletion. In conclusion, Caco-2 cells contain
an
active-transport system that is primarily involved in the secretion
of
glutathione conjugates and that is present in both plasma membrane
domains of the cell.
Title
Effects of liver damage induced by carbon tetrachloride on glutathione
and glutathione-dependent enzymes in rat gastric mucosa.
Author
Hosoda A; Yamada S; Kawasaki H
Address
Second Department of Internal Medicine, Faculty of Medicine,
Tottori
University, Yonago, Japan.
Source
Res Commun Chem Pathol Pharmacol, 79(2):141-50 1993 Feb
Abstract
The present study investigated the relationship between the
concentration of the reduced form of glutathione (GSH) and
GSH-dependent enzyme activities in the gastric mucosa during
acute
liver injury caused by carbon tetrachloride (CCl4) in rats. Transient
decreases in glutathione S-transferase (GST) activity and in
glutathione peroxidase (GSH-Px) activity was observed (p <
0.01). GSH
concentration also decreased (p < 0.01) but then transiently
increased
(p < 0.05). Gamma-glutamyltransferase (GGT) activities in
rats killed
6, 12, and 24 hr after exposure to CCl4 were all higher than
in the
control group (p < 0.01). There was a significant correlation
between
GSH concentration and GST activity (p < 0.05) and between
GSH
concentration and GSH-Px activity (p < 0.01). However, there
was no
correlation between GSH concentration and GGT activity. The gastric
mucosa, as judged by light microscopy, was slightly more damaged
in the
rats exposed to CCl4 than in the control group. From the observed
abnormalities of GSH and GSH-dependent enzymes in the gastric
mucosa of
the rats exposed to CCl4, changes in GSH content and GSH-related
enzymes in gastric mucosa may be important in gastric protection
during
acute liver injury.
Title
Purification and characterization of a glutathione peroxidase
from the
Aloe vera plant.
Author
Sabeh F; Wright T; Norton SJ
Address
Department of Biological Sciences, University of North Texas,
Denton
76201
Source
Enzyme Protein, 47(2):92-8 1993
Abstract
Extracts from the parenchymous leaf-gel of the Aloe vera plant
(Aloe
barbadensis Miller) were shown to contain glutathione peroxidase
(GSHPx) activity. The activity was purified to homogeneity by
ion
exchange and gel filtration (FPLC) chromatography in the presence
of
0.5 mM glutathione. The native enzyme has an apparent molecular
weight
of 62 kD as determined by gel filtration. In the presence of
sodium
dodecylsulfate (SDS), the molecular weight was estimated to be
about 16
kD as determined by polyacrylamide-gel electrophoresis (SDS-PAGE).
The
native enzyme is proposed to be constituted of four identical
subunits;
it also contains one atom of selenium per subunit, as found with
most
glutathione peroxidases from animal sources. The Km values were
determined to be 3.2 mM for glutathione and 0.26 mM for the
hydroperoxide substrate, cumene hydroperoxide. The enzyme is
competitively inhibited by N, S, bis-FMOC glutathione (Ki = 0.32
mM), a
potent inhibitor of glyoxalase II. Inhibitors of glyoxalase I
(e.g.
S-octylglutathione) have no effect on the peroxidase activity.
Title
Amino acid sequence of glutathione S-transferase a from guinea
pig
liver.
Author
Kamei-Hayashi K; Oshino R; Hara S
Address
Laboratory of Biochemistry, Kobe Yamate Women's College, Kobe.
Source
J Biochem (Tokyo), 114(6):835-41 1993 Dec
Abstract
The amino acid sequence of glutathione S-transferase a from guinea
pig
liver was determined. glutathione S-transferase a was composed
of two
identical subunits, each comprising 218 amino acid residues.
The amino
acid sequence of glutathione S-transferase a exhibited 73% homology
with that of human glutathione S-transferase Ha, 69% with that
of rat
glutathione S-transferase Ya, and 68% with that of rat glutathione
S-transferase Yc, which are known to belong to class Alpha. From
the
above result, together with previous observations on its substrate
specificity, it was concluded that glutathione S-transferase
a belonged
to class Alpha.
Title
Oxidative stress and antioxidant defence mechanism in Plasmodium
vivax
malaria before and after chloroquine treatment.
Author
Sarin K; Kumar A; Prakash A; Sharma A
Address
Department of Anthropology, University of Delhi, India.
Source
Indian J Malariol, 30(3):127-33 1993 Sep
Abstract
The protection of Plasmodium vivax-parasitized red blood cells
(PRBCs)
against activated forms of oxygen was examined in relation to
the
non-parasitized and chloroquine-treated red blood cells. Increased
parasitaemia was found to be accompanied with a decrease in the
activities of enzymes of the glutathione system, namely glutathione
peroxidase (GPx), glutathione reductase (GRx) and glutathione
S-transferase (GTr) in the red blood cells (RBC) lysates. In
contrast,
however, the total amount of reduced glutathione (GSH) and the
content
of water-soluble antioxidant vitamin C was increased 2-3 fold
over
those of control RBCs. Chloroquine-treated red cells contained
enzyme
activities and antioxidant contents (GSH, vitamin C) comparable
to
those of control and non-parasitized red cells. Our results therefore
indicate the oxidative stress experienced by RBCs during P. vivax
infection and that this infection is accompanied with changes
in the
antioxidant defence system of the host, which are restored to
near
normal levels after treatment with chloroquine.
Title
Systemic deficiency of glutathione in cystic fibrosis.
Author
Roum JH; Buhl R; McElvaney NG; Borok Z; Crystal RG
Address
Pulmonary Branch, National Heart, Lung, and Blood Institute,
National
Institutes of Health, Bethesda, Maryland 20892.
Source
J Appl Physiol, 75(6):2419-24 1993 Dec
Abstract
Cystic fibrosis (CF), a disorder characterized by mutations of
the CF
transmembrane regulator gene, is characterized in the lung by
chronic
inflammation, leading to progressive damage to the airway epithelium,
bronchiectasis, and chronic obstructive lung disease. One process
contributing to the airway derangement is the chronic burden
of
oxidants released by inflammatory cells on the respiratory epithelial
surface. With this background, we hypothesized that glutathione
in
respiratory epithelial lining fluid (ELF) in CF patients might
be
oxidized and/or diminished in amount compared with that in normal
subjects. Recovery of ELF by bronchoalveolar lavage from young
adults
with CF (n = 21) and normal subjects (n = 25) demonstrated marked
neutrophil-dominated inflammation in ELF in CF patients. As predicted,
ELF in CF patients was characterized by a deficiency of glutathione
(P
< 0.001), but this was secondary to a reduction in reduced
glutathione
(P < 0.001), inasmuch as there were no differences in ELF
levels of
oxidized glutathione (P > 0.2). Unexpectedly, there was also
a marked
deficiency of reduced glutathione in plasma (P < 0.02); i.e.,
the
glutathione "deficiency" observed in ELF in CF patients
is not limited
to the site of the inflammation but is systemic. Although the
etiology
of this generalized deficiency of extracellular glutathione is
unknown,
it is important in considering options for treating the concomitant
and
devastating lung pathology in this disorder.
Title
glutathione-related detoxication functions in streptozotocin-induced
diabetic rats.
Author
Saito-Yamanaka N; Yamanaka H; Nagasawa S
Address
National Institute of Animal Health, Ibaraki, Japan.
Source
J Vet Med Sci, 55(6):991-4 1993 Dec
Abstract
In order to analyze the detoxication functions in rats with diabetes
induced by streptozotocin, the authors administered to the diabetic
animals two drugs, ethionine and benzo(a)pyrene, which affect
mainly
the liver and are metabolized through a glutathione conjugation
process, and examined the changes in the content of glutathione
and
activities of related enzymes in the liver. In the liver of the
rats
with streptozotocin-induced diabetes, the total glutathione content,
glutathione S-transferase activity and glutathione-insulin
transhydrogenase activity were lower than those of normal rat
livers,
while the glutathione peroxidase activity showed high values.
Although
specific changes in the glutathione-related detoxication functions
were
observed in the rats to which ethionine or benzo(a)pyrene had
been
administered, these changes were not revealed under diabetic
conditions. It is suggested that in diabetic rats responses to
toxic
stimuli are suppressed. |
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