...
Apoptosis, an active process of cell destruction with
specifically-defined morphological and molecular features,
is considered a beneficial process whereby organisms
eliminate ‘unwanted’, i.e. old, precancerous
or excessive, cells without further nearby tissue
injuries shown in necrosis. However,
in central nervous tissues that have a limited capacity
for self-renewal, apoptotic cell death may result
in physiological or pathological disorders, which
may underlie the etiology of neurodegenerative diseases...
Excerpt
from: Yun-Bae
Kim et al. Organophosphate-induced brain injuries:
delayed apoptosis mediated by nitric oxide. Environmental
Toxicology and Pharmacology. April 1999. 7:2;147-152
.
|
The term 'apoptosis' describes
the molecular and morphological processes leading to controlled
cellular self-destruction and was first introduced
in a publication by Kerr, Wyllie and Currie (Br. J. Cancer,
1972, 26: 239). 'Apoptosis' is of greek origin, having the
meaning "falling off or dropping off", in analogy
to leaves falling from trees or petals from flowers. By choosing
this term, the authors might have intended to stress that
this form of cell death is a natural phenomenon, an active
and defined process which plays an important role in the regulation
of the cell population in tissues upon physiological and pathological
conditions. Apoptotic cell death can be induced by a variety
of stimuli, such as ligation of cell surface receptors, starvation,
growth factor/survival factor deprivation, heat shock, hypoxia,
DNA damage, viral infection, and cytotoxic/chemotherapeutical
agents. The apoptotic process is of widespread biological
significance, and it was reported to be involved in embryogenesis,
differentiation, proliferation/homoeostasis, removal of defect
and therefore harmful cells, and especially in the regulation
and function of the immune system. Thus, dysfunction
or disregulation of the apoptotic program is implicated in
a variety of pathological conditions, such as immunodeficiency,
auto-immune diseases, neurodegenerative diseases, and cancer.
Apoptotic cells can be recognized by stereotypical morphological
changes: the cell shrinks, shows deformation and looses contact
to its neighbouring cells. Its chromatin condenses, and finally
the cell is fragmented into compact membrane-enclosed structures,
called 'apoptotic bodies' which contain cytosol, the condensed
chromatin, and organelles. The apoptotic bodies are engulfed
by macrophages and thus are removed from the tissue without
causing an inflammatory response. This is in contrast to the
necrotic mode of cell-death in which case the cells suffer
a major insult, resulting in loss of membrane integrity, swelling
and disrupture of the cells. During necrosis, the cell contents
are released uncontrolled into the cell's environment what
results in damage of surrounding cells and a strong inflammatory
response in the corresponding tissue.
Frequently, the terms 'apoptosis' and 'programmed cell death'
are used as synonyms. Programmed cell death was originally
used in order to describe the locally and temporally defined
cell death during embryogenesis. It was already in the middle
of our century that cell death was recognized as a natural
process in the development of organisms (Gluecksmann, 1951,
Biol. Rev., 26: 59).
Ref: http://www.celldeath.de/encyclo/index.html
Note from FAN: The website Apoptopedia
is simply a brilliant website, from which the above short
description comes from. If you seek more information on this
subect, the best place to start is http://www.celldeath.de/encyclo/index.html
or http://www.celldeath.de/
- EC,
The
use of high doses increases the likelihood that potentially
significant toxic effects will be identified. Findings
of adverse effects in any one species do not necessarily
indicate such effects might be generated in humans. From
a conservative risk assessment perspective however, adverse
findings in animal species are assumed to represent potential
effects in humans, unless convincing evidence of species
specificity is available.
--
Food and Agricultural Organization of the United Nations
|
•
When time allows more information will be added.
DFP:
Diisopropyl fluorophosphate
- Insecticide - CAS No. CAS No. 55-91-4
Abstract: The
features of organophosphate-induced brain injuries were investigated.
Rats were poisoned intraperitoneally with 9 mg/kg (1.8 LD50) of
diisopropylfluorophosphate [synonym
for DFP]
. Pyridostigmine bromide (0.1 mg/kg) and atropine methylnitrate
(20 mg/kg), which are centrally inactive, were pre-treated intramuscularly
to reduce the mortality and eliminate peripheral signs. Diisopropylfluorophosphate
induced severe limbic seizures, and early necrotic and delayed
apoptotic brain injuries. The necrotic
brain injury was observed to be maximal as early as 1 h after
diisopropylfluorophosphate treatment predominently in hippocampus
and piriform/entorhinal cortices, showing a spongiform change
(malacia) of neuropils in severe cases.
In contrast, typical apoptotic (TUNEL-positive) cells started
to appear at 12 h in thalamus, and a mixed type in amygdala. Separately,
nitrite/nitrate content in cerebrospinal fluid was found to significantly
increase after 2 h, reaching a maximal level at 6 h. Pre-treatment
with -NG-nitroarginine, an inhibitor of nitric oxide synthase,
reduced nitrite/nitrate content and, noteworthy, attenuated only
apoptotic brain injury in all four brain regions without affecting
seizure intensity and necrotic injury. Taken together, the
delayed apoptotic injury of brain induced by diisopropylfluorophosphate
poisoning in rats might be mediated in part through nitric
oxide production.
Ref:
Organophosphate-induced brain injuries: delayed apoptosis mediated
by nitric oxide by Yun-Bae Kim et al. Environmental Toxicology
and Pharmacology Vol 7, Issue 2 , April 1999, Pages 147-152
PFOA
- Insecticide, US EPA List 3 Inert
Abstract excerpt:
"... one of the most potent rodent
hepatocarcinogens, perfluorooctanoic acid (PFOA), induces apoptosis
in human HepG2 cells in a dose- and time-dependent manner...
In summary, we have delineated a ROS [reactive oxygen species]
and mitochondria-mediated pathway for induction of apoptosis
by PFOA."
Ref: 2001. Toxicol Appl Pharmacol May
15;173(1):56-64.
Reactive oxygen species and mitochondria mediate the induction
of apoptosis in human hepatoma HepG2 cells by the rodent peroxisome
proliferator and hepatocarcinogen, perfluorooctanoic acid;
by Panaretakis T, Shabalina IG, Grander D, Shoshan MC, DePierre
JW.
Abstract excerpt:
The effects of perfluorooctanoic acid (PFOA), a potent hepatocarcinogen
and peroxisome proliferator in rodents, on human cells have
not yet been examined. In the present study we
demonstrate that treatment of human hepatoblastoma HepG2 cells
with PFOA induces apoptosis, as well as perturbs the cell cycle...
Simultaneous flow cytometric analysis of apoptosis-associated
DNA strand breaks using the TUNEL procedure and of propidium
iodide staining of cellular DNA revealed DNA breaks in HepG2
cells exposed to 150 microM PFOA, prior to nuclear fragmentation.
Ref: 1999. Carcinogenesis Dec;20(12):2237-46.
Effects of the rodent peroxisome proliferator and hepatocarcinogen,
perfluorooctanoic acid, on apoptosis in human hepatoma HepG2
cells; by Shabalina IG, Panaretakis T, Bergstrand A, DePierre
JW. Full report available free at:
http://carcin.oupjournals.org/cgi/content/full/20/12/2237
Abstract:
Perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA),
clofibrate, di(2-ethylhexyl)phthalate (DEHP), and Wy-14,643
represent a class of compounds known as peroxisome proliferators
(PPs). Such compounds induce biogenesis of liver peroxisomes
and cause a varying degree of hepatotoxicity and carcinogenesis
in rodents. We examined the effects of these PPs on rat hepatic
lipids and phospholipid profiles using phosphorus-31 NMR spectroscopy.
All PPs caused a 25-57% increase in hepatic phospholipid content,
while all but clofibrate increased the total lipid content by
26-156%. Treatments also influenced the composition of liver
phospholipids. Phosphatidylcholine (PtdCho) and phosphatidylethanolamine
(PtdEth) contents were significantly increased in all treatment
groups. Most notably, PFDA caused the largest increase in PtdCho
and PtdEth content (ca. 70%), while PFOA and Wy-14,643 were
the only test compounds that influenced the PtdCho:PtdEth ratio.
PFDA also caused an ca. 30% decrease in sphingomyelin (SphM)
from 24 to 120 h postdose. SphM is a key lipid in signal transduction
processes involved in apoptosis. Hydrolysis of SphM can be mediated
through the action of tumor necrosis factor (TNF-alpha). We
measured the TNF-alpha concentrations in rat sera at 24 h post-PFDA-exposure
and found an 8-fold increase relative to vehicle-treated controls.
These data demonstrate that an increase in the serum TNF-alpha
level correlates with the time frame for the observed reduction
in hepatic SphM. PFOA, a structurally similar compound, had
no effect on hepatic SphM content, nor did it affect the serum
TNF-alpha concentration. These effects may be related to differences
in the tumorigenicity associated with these compounds.
We postulate that PFDA activates the SphM signal transduction
pathway via the release of TNF-alpha. This then stimulates cytotoxic
responses and processes of apoptosis and may suppress cell proliferative
and mitogenic responses.
Ref:
1998. Chem Res Toxicol May;11(5):428-40.
Effects of peroxisome proliferators on rat liver phospholipids:
sphingomyelin degradation may be involved in hepatotoxic mechanism
of perfluorodecanoic acid; by Adinehzadeh M, Reo NV.
Chronic & Carcinogenicity
Studies. Findings in other organs included enlarged cervical
lymph nodes at 800 and 1250 ppm, prominent alveolar macrophages
in the lungs of males at 1250 ppm and females of all treated groups,
pneumonitis in females at 800 and 1250 ppm, involution in the
thymus of males at 1250 ppm, and amyloidosis
in various organs of mainly males at 800 and 1250 ppm. ...Dogs
received 0, 22.5, 90 or 360 ppm of tetraconazole in the diet for
1 year. Histopathology detected apparent hepatocyte enlargement,
eosinophilic inclusions in hepatocytes, centrilobular hepatocyte
rarefaction, or centrilobular fat in the liver at 90 and 360 ppm,
and cortical tubular hypertrophy and apoptotic
bodies in the kidneys at 360 and/or 90 ppm. The NOEL was
22.5 ppm (0.7 mg/kg bw/day). (page 5)
Ref: August
2005 - Evaluation of Tetraconazole in the product Domark 40ME
Fungicide. Australian Pesticides and Veterinary Medicines Authority.
http://www.fluorideaction.org/pesticides/tetraconazole.2005.report.australia.pdf
Sodium fluoride - Insecticide,
Wood preservative, US EPA List 4B Inert -
CAS No.
7681-49-4
•
Note: The following is a limited selection of abstracts from 1994
to present.
Anticancer
Res. 2003 Sep-Oct;23(5A):3719-26.
Effect of antioxidants, oxidants, metals and saliva on
cytotoxicity induction by sodium fluoride.
Tokunaga
T, Morshed SR, Otsuki S, Takayama F, Satoh T, Hashimoto K, Yasui
T, Ogawa S, Kanegae H, Yokote Y, Akahane K, Kashimata M, Satoh
K, Sakagami H.
Department of Dental Pharmacology, Meikai University School of
Dentistry, Sakado, Saitama, Japan.
We have recently found that millimolar concentrations
of sodium fluoride (NaF) induced apoptotic cell death, characterized
by caspase activation and DNA fragmentation, in tumor cell lines.
This finding paved the way to investigating the interaction between
NaF and the oral environment. As an initial step, we investigated
redox compounds, metals and saliva, which may modify the cytotoxic
activity of NaF against a human oral squamous cell carcinoma cell
line (HSC-2). The minimum exposure time to NaF required for cytotoxicity
induction was 8 hours. Noncytotoxic concentrations of antioxidants
(sodium ascorbate, gallic acid, epigallocatechin gallate, chlorogenic
acid, curcumin, superoxide dismutase, catalase), oxidants (hydrogen
peroxide, sodium hypochlorite), metals (CuCl, CuCl2, FeCl2, FeCl3,
CoCl2) or saliva neither protected against, nor enhanced the cytotoxic
activity of NaF. Cytotoxic concentrations of these compounds produced
somewhat additive, but not synergistic, effects on the cytotoxicity
of NaF. ESR analysis demonstrated that NaF did not apparently
change the radical intensity of sodium ascorbate and gallic acid,
measured under alkaline conditions. During the cell death induction
in human promyelocytic leukemia HL-60 cells by NaF, the consumption
of glucose rapidly declined, followed by a decline in the consumption
of major amino acids. The present study
suggests that the cytotoxic activity of NaF is not regulated by
the redox mechanism, but rather linked to the rapid decline in
glucose consumption at early stage.
PMID: 14666669 [PubMed - in process]
Wei
Sheng Yan Jiu. 2003 Sep;32(5):432-3.
[Effects of fluoride on cell cycle and apoptosis in cultured
osteoblasts of rats]
[Article in Chinese]
Zhang Y, Sun G, Jin Y, Wang Y.
School of Public Health, China Medical University, Shenyang 110001,
China.
To study the effects of fluoride on cell growth, cell cycle and
apoptosis in cultured osteoblasts of rats. The enzymes digesting
method was used to isolate the osteoblasts of rats. The activity
of the cells was determined by the percents of reduced AlamarBlue.
FCM was used to analyze cell cycle and apoptosis. The results
showed that the activity of rat osteoblast was not influenced
by NaF at 0 to 2 mmol/L concentration after 24 hours incubation.
At the concentration of 2 mmol/L, the number of cells at S phase
was increased. At the concentration of 4 mmol/L, NaF increased
the number of cells at S phase and at the same time, decreased
the number of cells at G2/M phase, but the number of the cells
at G0/G1 phase kept unchanged. The percent of apoptosis was increased
at the concentration of 2 mmol/L. Excessive
fluoride could affect the cell activity, retarded cell cycle at
S phase and induced apoptosis.
PMID:
14650182 [PubMed - in process]
Fluoride-induced apoptosis in human epithelial lung cells (A549
cells): role of different G protein-linked
signal systems.
Refsnes
M, Schwarze PE, Holme JA, Lag M.
Division of Environmental Medicine, Norwegian Institute of Public
Health, Geitmyrsvn. 75, PO Box 4404 Nydalen, N-0403 Oslo, Norway.
magne.refsnes@fhi.no
In the present study, possible mechanisms involved in fluoride-induced
apoptosis in a human epithelial lung cell line (A549) were examined.
Sodium fluoride (NaF) induced apoptosis in the A549 cells,
with a maximum at 5-7.5 mM after 20 hours of exposure. The
number of cells with plasma membrane damage (PI-positive cells)
increased moderately up to 5 mM, but markedly at 7.5 mM.
Deferoxamine (an Al3+ chelator) almost completely prevented these
NaF-induced responses, which may suggest a role for G protein
activation. The apoptotic effect was partially reduced by the
PKA inhibitor H89. NaF induced a weak but sustained increase in
PKC activity, whereas the PKC activator TPA induced a transient
effect. TPA, which enhanced the NaF-induced PKC activity, was
not apoptotic when added alone, but facilitated the NaF-induced
apoptosis and the increase in PI-positive cells. PKC downregulation
induced by TPA pretreatment almost completely prevented the NaF-induced
apoptosis and the increase in PI-positive cells. Pretreatment
with the PKC inhibitor GF109203X, which abolished the PKC activity
after 3 hours, enhanced the NaF-induced apoptosis. KN93 (a CaM
kinase II inhibitor) and W7 (a calmodulin inhibitor) seem to reduce
the apoptotic effect of NaF, whereas BAPTA-AM (a Ca2+ chelator)
was without effect. The tyrosine kinase inhibitor genistein also
markedly reduced the NaF-induced apoptosis, whereas the PI-3 kinase
inhibitor wortmannin augmented the response. In conclusion, the
present results suggest that NaF induces an apoptotic effect and
an increase in PI-positive A549 cells via similar mechanisms,
involving PKC, PKA, tyrosine kinase and Ca2+-linked enzymes, whereas
PI-3 kinase seems to exert a counteracting effect.
PMID: 12723891 [PubMed - in process]
Carcinogenesis
2003 Jan;24(1):7-15
Short-term
depletion of catalase suppresses cadmium-elicited c-Jun N-terminal
kinase activation and apoptosis: role of
protein phosphatases.
Chuang
SM, Wang IC, Hwua YS, Yang JL.
Molecular Carcinogenesis Laboratory, Department of Life Sciences,
National Tsing Hua University, Hsinchu 300, Taiwan, Republic of
China.
The c-Jun N-terminal kinase (JNK) is a vital stress-activated
signal that can be regulated differentially under oxidant or antioxidant
conditions. Recently, we have reported that activation of JNK
by cadmium chloride (Cd) contributes to apoptosis in CL3 human
lung adenocarcinoma cells. Although oxidative stress has been
implicated in numerous biochemical effects altered by Cd, its
role in Cd-elicited JNK activation has not been established. Here
we report that catalase is crucial for the activation of JNK by
Cd. Short-term treatment of 3-amino-1,2,4-triazole (3AT), a specific
catalase inhibitor, completely suppressed the Cd-elicited JNK
activation, conversely, exogenous addition of catalase increased
the intensity and duration of JNK activation in Cd-treated CL3
cells. Co-administering high doses of H(2)O(2) (500-1000 micro
M) with Cd also markedly decreased JNK activity, although at doses
<200 micro M H(2)O(2) enhanced the Cd-elicited JNK activation
in CL3 cells. 3AT also blocked JNK activation in Cd-treated normal
human fibroblasts and Chinese hamster ovary cells, and in UV-irradiated
CL3 cells. However, mannitol, a hydroxyl radical scavenger, did
not alter the JNK activity in Cd-treated human and rodent cells.
Intriguingly, sodium fluoride or okadaic
acid, inhibitors for serine/threonine protein phosphatases (PP),
recovered the JNK activity in CL3 cells exposed to Cd plus 3AT;
however, the protein tyrosine phosphatases inhibitor sodium orthovanadate
did not. Furthermore, 3AT decreased but catalase increased the
Cd-induced cytotoxicity, apoptosis and procaspase-3 degradation
in CL3 cells. Together, these results indicate that persistent
activation of apoptotic JNK signal by Cd requires functional catalase
and that short-term depletion of catalase activity may facilitate
okadaic acid-sensitive PP to down-regulate the JNK activation
and may predispose these cells to carcinogenic transformation
upon Cd exposure.
PMID: 12538343
[PubMed - in process]
Studies on DNA damage
and apoptosis in rat brain
induced by fluoride.
Chen
J, Chen X, Yang K, Xia T, Xie H.
Department of Environmental Health, Tongji Medical College, Huazhong
University of Science and Technology, Wuhan 430030, China.
OBJECTIVE: To explore the DNA damage effects and apoptosis in
brain cells of rats induced by sodium fluoride.
METHODS: SD rats were divided into two groups, i.e. control group
and fluoride treated group, which
were injected intraperitoneally with distilled water and sodium
fluoride (20 mg.kg(-1).d(-1)) respectively. On the hand, 5 mmol/L
NaF were used in in vitro study.
Single Cell Gel Electrophosis (SCGE or Comet Assay) was utilized
to measured DNA damage and apoptosis was detected by the TUNEL
method and Flow Cytometry (FCM).
RESULTS: The DNA damage in pallium neurons
in rats of the fluoride group was
much more serious compared with those of the control guoup, with
the Ridit value being 0.351 and 0.639 respectively (P < 0.01)
in vivo, and 0.384 4 and 0.650 1 respectively (P < 0.01) in
vitro. TUNEL positive cells were found in pallium,
hippocampus and cerebellar granule cells in rats of fluoride
group, whereas those in the control group were rare. It was demonstrated
by FCM results that the percentages of apoptotic cells both in
pallium and hippocampus were significantly
higher (P < 0.01) in rats of fluoride group (27.12 +/-
3.08, 34.97 +/- 5.46) than those in control group (4.63 +/- 0.98,
5.35 +/- 0.79), (P < 0.01).
CONCLUSION: Sodium fluoride could induce
DNA damage and apoptosis in rats brain.
PMID: 12411198 [PubMed - as supplied by publisher]
No Abstract available
Involvement of protein kinase C in fluoride-induced
apoptosis in different types of lung cells.
Refsnes
M, Kersten H, Schwarze PE, Lag M.
Division of Environmental Medicine Norwegian Institute of Public
Health, N-0403 Oslo, Norway. magne.refsnes@fhi.no
PMID: 12485864 [PubMed - indexed for MEDLINE]
Effects of selenium and fluoride on
apoptosis and lipid peroxidation
in human hepatocytes.
Wang
A, Xia T, Ran P, Bai Y, Yang K, Chen X.
Department of Environmental Health, Tongji Medical College of
Huazhong University of Science and Technology, Wuhan 430030, China.
OBJECTIVE: To study the influence of selenium and fluoride on
apoptosis and lipid peroxidation in human hepatocytes in vitro.
METHODS: The apoptosis, cell cycle, GSH content and lipid peroxides
(LPO) level in human hepatocytes, LPO level and LDH, AST and ALT
activity in cell culture supernatants were investigated after
hepatacytes were incubated with selenium and/or fluoride for around
12 hours periods in vitro.
RESULTS: The percentage of hepatocyte apoptosis bodies (15.557
+/- 2.056)%, the number of cells in S phase (4.823 +/- 0.454)%
and LPO level in liver tissue and supernatant [(2.884 +/- 0.589)
and (3.547 +/- 0.561) nmol/L MDA/mg.prot, respectively], AST and
LDH activity in supernatants (91.1 +/- 36.4 and 140.4 +/- 7.6
U/L, respectively) in the fluoride treated group was higher than
the control group [(10.313 +/- 1.023)%, (3.253 +/- 0.743)%, (1.473
+/- 0.401) nmol/L MDA/mg.prot, (1.694 +/- 0.443) nmol/L MDA/mg.prot,
(54.5 +/- 3.2) U/L and (126.4 +/- 2.6) U/L, respectively], The
GSH content in live tissue [(4.225 +/- 0.781) micro g/mg.prot]
is lower than control group [(7.595 +/- 1.042) micro g/mg.prot].
Selenium treatment reduced these kinds of toxicity of fluoride
through raising GSH content, reducing LPO level, LDH and AST activity
and percentage of apoptosis bodies.
CONCLUSIONS: Selenium can antagonist apoptosis
and lipid peroxidation of hepatocytes induced by fluoride.
PMID: 12411202 [PubMed - in process]
[Effects of selenium and zinc on rat renal
apoptosis and change of cell cycle induced by fluoride]
[Article in Chinese]
Yu R, Xia T, Wang A, Chen X.
Department of Environmental Health, Tongji Medical College, Huazhong
University of Science and Technology, Wuhan 430030, China.
OBJECTIVE: This study was conducted to study the effects of sodium
fluoride (NaF) on rat renal apoptosis and proliferation, the antagonistic
effect of selenium-zinc preparation (Se-Zn) to NaF.
METHODS: Wistar rats were provided with distilled water containing
NaF (50 mg/L) and administered by gavage with different dosed
of Se-Zn for six months. Kidney cell apoptosis and the cell cycle
of proliferation were detected by TUNEL (TdT-mediated dUTP Nick
End Labelling) and flow cytometry.
RESULTS: NaF caused rat renal apoptosis,
reduce the cell number of G(2)/M period in cell cycle and decrease
the relative content of DNA significantly. Se-Zn inhibited
the effects of NaF on apoptosis and increased the cell number
of G(2)/M period in cell cycle, but failed to increase relative
content of DNA.
CONCLUSION: It was suggested that NaF could
induce apoptosis and change the cell cycle in rat renal cells
and Se-Zn could antagonize apoptosis and the changes of cell cycle
induced by NaF.
PMID: 12411197 [PubMed - indexed for MEDLINE]
Differential effects of genistein on apoptosis
induced by fluoride and pertussis toxin in human and rat pancreatic
islets and RINm5F cells.
Elliott
J, Scarpello JH, Morgan NG.
Cellular Pharmacology Group, School of Life Sciences, Keele University,
Keele, Staffordshire ST5 5BG, UK.
Clonal pancreatic beta-cell lines have been
used widely for the study of the factors involved in the regulation
of apoptosis but it has not been firmly established that the response
of normal islets mirrors that found in transformed beta-cells.
In the present work, the role of pertussis toxin (Ptx)-sensitive
G-proteins in the control of beta-cell apoptosis was studied in
isolated rat and human islets of Langerhans and compared
with the clonal beta-cell line, RINm5F. Annexin-V and deoxycarboxyfluoroscein
diacetate staining was used to identify viable, apoptotic and
necrotic cells directly, under fluorescence illumination. Treatment
of human and rat islet cells with the G-protein activator fluoride
(NaF; 5 mM) caused a marked increase in apoptosis that was further
potentiated in islets pretreated with Ptx. The tyrosine
kinase inhibitor genistein (100 microM) also increased islet cell
apoptosis and the combination of 100 microM genistein and
5 mM NaF did not lead to any diminution of the apoptotic response.
This latter effect was quite different from that seen in RINm5F
cells where the combination of 100 microM genistein and 5 mM NaF
resulted in much less apoptosis than was observed with either
agent alone. In islets treated with
a lower concentration of genistein (25 microM; that did not, itself,
increase cell death), the drug attenuated NaF-induced apoptosis
and also blocked the enhancement mediated by Ptx. These
results revealed that human (and rat) islets are equipped with
a Ptx-sensitive pathway that may be regulated by tyrosine phosphorylation
and is anti-apoptotic. However, they also define conditions under
which marked differences in response between RINm5F cells and
normal islets were observed and they suggest that care
should be taken when extrapolating data obtained with clonal cell
lines to the situation in normal islet cells.
PMID: 11786381 [PubMed - indexed for MEDLINE]
[Expression of Fas, FasL, and NF-kappa B in the process of osteoclast-like
cell apoptosis effected by sodium
fluoride]
[Article in Chinese]
Sun YM, Yang FJ, Li YM, Lu B, Zhu M, Qiu MC.
Department of Radiobiology, Institute of Radiation Medicine, CAMS,
PUMC, Tianjin 300192, China.
OBJECTIVE: To detect the changes in the expression of apoptosis
signals: Fas, FasL and NF-kappa B in the process of osteoclast-like
cell (OLC) apoptosis effected by sodium fluoride.
METHODS: After co-culture of osteoclast-like cells with 0, 5,
10 and 15 mg/L sodium fluoride, Fas, FasL and NF-kappa B antibody
expressions were detected by immune-histochemistry.
RESULTS: The expression of Fas and FasL increased with the concentration
of the sodium fluoride, however the expression of NF-kappa B decreased
with the concentration of sodium fluoride.
CONCLUSION: In the process of OLC apoptosis
induced by sodium fluoride, the expression of Fas and FasL
increased, and that of NF-kappa B decreased with the concentration
of sodium fluoride respectively, and the changes of the expression
present a dose-dependent pattern.
PMID:
12905771 [PubMed - in process]
Note:
The following is the article, without graphs, as it appeared in
this journal. We present this as PubMed did not provide an abstract.
Annals of the New York Academy of Sciences 973:218-220 (2002)
Involvement of Protein Kinase C in Fluoride-Induced
Apoptosis in Different Types of Lung Cells
M. REFSNES, H. KERSTEN, P. E. SCHWARZE and M. LG
Division of Environmental Medicine Norwegian Institute of Public
Health, N-0403 Oslo, Norway Address for correspondence: Dr. M.
Refsnes, Division of Environmental Medicine, Norwegian institute
of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
Voice: +4722042533; fax: +4722042686. magne.refsnes@fhi.no
INTRODUCTION The lung is a target for fluoride-induced
toxicity. Fluoride is known to induce apoptosis in different cell
types. We previously showed that sodium fluoride (NaF)
induced apoptosis in a human epithelial lung cell line (A549)
and in epithelial type 2 cells isolated from rat lung, the type
2 cells being most sensitive. Involvement of different MAP kinases
was also demonstrated. In the present study, the ability of NaF
to induce apoptosis in rat alveolar macrophages and A549 cells
was compared, and the role of protein kinase C (PKC) in the apoptotic
process was examined.
METHODS
A549 cells, presumably originating from human type 2 cells, were
cultured as previously described. Primary rat alveolar macrophages
were isolated by bronchoalveolar lavage. The macrophages were
cultured in RPMI 1640 medium, with antibiotics and 5% fetal bovine
serum for 1 hour at a density of 1.5 x 106 cells per milliliter,
and the attached macrophages were used for further studies. Both
cell types were exposed to NaF and assessed for PKC activity and
apoptosis. In some experiments the cells were pretreated with
TPA (100 nM) for 20 hours to down-regulate PKC or with the PKC
inhibitor GF109203X (20 µM) for 1 hour and further incubated with
NaF. The PKC activity was measured by a commercial assay (Amersham).
Apoptosis was measured by flow cytometry.
RESULTS
AND DISCUSSION NaF induced more marked apoptosis
in macrophages than in A549 cells and at much lower concentrations.
This may reflect the difference between cells from different species,
but more conceivably reflects the use of primary lung cells versus
an established tumor cell line. Furthermore,
NaF induced a slight, but significant increase in PKC activity
in both cell types. PKC down-regulation induced by TPA
pretreatment prevented these increases, but more importantly it
strongly reduced basal PKC activity. PKC down-regulation
almost completely prevented NaF-induced apoptosis in both cell
types, suggesting that PKC may allow NaF-induced apoptosis. GF109203X
inhibited PKC activity to the same extent as did TPA pretreatment
. Surprisingly, GF109203X increased the apoptosis of A549 cells
and was without effect on macrophages . The reason for the lack
of an inhibitory effect is unclear, but it may indicate that the
effect of GF109203X is too transient to suppress apoptosis or
that GF109203X cannot inhibit a specific PKC isoform crucial for
the apoptotic response. In conclusion, NaF
induced apoptosis in both rat alveolar macrophages and A549 cells
via mechanisms that involved PKC.
Fluoride 2001;
34(3 ):165-173
Effect
of fluoride on thyroid function and cerebellar
development in mice
Mahmoud Trabelsi (a), Fadhel Guermazi (b), Najiba Zeghal (c)
(a) Synthesis and Physical-Organic Chemistry Laboratory, Faculty
of Sciences-Sfax;
(b) Nuclear Medicine Service, CHU Habib Bourguiba-Sfax.
(c) For correspondence: Dr N Zeghal, Animal Physiology Laboratory,
Department of Biology, Facult des Sciences de Sfax-Route de la
Soukra-Km 3.5, 3038 Sfax BP802, Tunisia. Email: Nejiba.Zghal@fss.rnu.tn
SUMMARY: The effect of fluoride on
murine thyroid function and cerebellar development was studied
by administering NaF in drinking
water (0.5 g/L) to pregnant and lactating mice, from the 15th
day of pregnancy to the 14th day after delivery. Compared to a
control group, the NaF-treated pups,
at age 14 days, showed a 35% decrease in body weight, a 75% decrease
in plasma free T4, and reductions in the cerebellar and cerebral
protein concentrations by 27% and 17%, respectively. Consistent
histological changes were present in the cerebellum of the treated
mice with the external granular layer being markedly reduced or
absent, the Purkinje cell bodies being poorly differentiated and
arranged in a single layer at the surface of the internal granular
layer, and with more apoptotic Purkinje
cells being present.
Toxicological Sciences 61, 83-91 (2001)
Fluoride-Induced
Apoptosis in Epithelial Lung
Cells Involves Activation of MAP Kinases p38 and Possibly JNK
E.
V. Thrane*, M.
Refsnes*, G. H. Thoresen, M.
Låg* and P. E. Schwarze*,1
* Department of Environmental Medicine, National Institute
of Public Health, Oslo, Norway; and Department of Pharmacology,
Faculty of Medicine, University of Oslo, Oslo, Norway.
1 To whom correspondence should be addressed at the Department
of Environmental Health, NIPH, 4404 Torshov, 0403-Oslo, Norway.
Fax: + 47 22 04 22 43. E-mail: per.schwarze@folkehelsa.no.
Exposure to fluorides can induce inflammatory reactions, cell
cycle arrest, and apoptosis in different experimental systems.
Fluorides are known G-protein activators, but less is known
about fluoride effects downstream of G-protein activation.
The aim of this study was to elucidate whether the
induction of apoptosis by fluorides and inhibition
of proliferation is mediated by MAP kinases in primary
rat lung, alveolar type 2 cells and the human epithelial
lung cell line A549. Sodium fluoride (NaF)
induced apoptosis in both cell types but at different concentrations,
with the primary cells being more sensitive to NaF.
Proliferation of the type 2 cells and A549 cells was
inhibited in the presence of NaF. NaF induced a prolonged
activation of MAP kinase ERK. NaF also activated p38
and JNK in A549 cells for several hours (maximally
6-fold and 3-fold increase, respectively). Inhibition of
ERK with the MEK1,2 inhibitor PD98059 increased apoptosis
2-fold, whereas the inhibitor of p38, SB202190, decreased
the level of apoptotic cells by approximately 40%.
SB202190 also inhibited apoptosis by almost 40% when
ERK activity was reduced in the presence of PD98059.
Neither PD98059 nor SB202190 did affect the NaF-induced
inhibition of proliferation. These observations
indicate that activation of MAP kinases p38 and possibly
JNK are involved in NaF-induced apoptosis of epithelial
lung cells, whereas ERK activation seems to
counteract apoptosis in epithelial lung cells. In contrast,
activation of ERK and p38 are not involved in NaF-induced
inhibition of cell proliferation.
Free
Radic Biol Med 2001 Aug 1;31(3):367-73
Oxidative damage to mitochondria is a preliminary step to caspase-3
activation in fluoride-induced apoptosis
in HL-60 cells.
Anuradha
CD, Kanno S, Hirano S.
Regional Environment Division, National Institute for Environmental
Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305 8506, Japan.
It has been suggested that oxidative stress
plays a major role in various forms of cell death, including necrosis
and apoptosis. We have previously reported that fluoride (NaF)
induces apoptosis in HL-60 cells by caspase-3 activation.
The main focus of this investigation was to arrive at a possible
pathway of the apoptosis induced by NaF
upstream of caspase-3, because the mechanism is still unknown.
The present study showed that after exposure to
NaF, there was an increase in MDA and 4-HNE and a loss
of mitochondrial membrane potential (deltaPsi(m)) was also observed
in NaF-treated cells.There was a
significant increase in cytosolic
cytochrome c, which is released from the mitochondria. We have
reported a downregulation of Bcl-2 protein in NaF-treated
cells. The antioxidants N-acetyl cysteine (NAC), glutathione (GSH)
protected the cells from loss of deltaPsi(m), and there was no
cytochrome c exit or Bcl-2 downregulation, and we suggest that
these antioxidants prevent apoptosis induced by NaF.
These results suggested that perhaps NaF
induced apoptosis by oxidative stress-induced lipid peroxidation,
causing loss of deltaPsi(m), and thereby releasing cytochrome
c into the cytosol and further triggering the caspase cascade
leading to apoptotic cell death in HL-60 cells.
PMID: 11461774 [PubMed - indexed for MEDLINE]
Br
J Pharmacol 2001 Jan;132(1):119-26
Effects of tyrosine kinase inhibitors on cell
death induced by sodium fluoride and pertussis toxin in
the pancreatic beta-cell line, RINm5F.
Elliott
J, Scarpello JH, Morgan NG.
Cellular Pharmacology Group, School of Life Sciences, Keele University,
Keele, Staffs ST5 5BG.
1. Sodium fluoride causes apoptosis
of pancreatic beta-cells and this response is enhanced by pre-treatment
with pertussis toxin. In the present study, tyrosine kinase inhibitors
were used to investigate the mechanisms of action of NaF
and pertussis toxin in the beta-cell line, RINm5F.
2. Exposure of RINm5F cells to low concentrations
of genistein or tyrphostin A25 resulted in significant inhibition
of cell death induced by 5 mM NaF. Higher concentrations
(>25 microM) were cytotoxic in the absence of
NaF but, paradoxically, the combination of genistein and
NaF induced less cell death than
when each agent was used alone.
3. The increase in cell death induced by 100 microM genistein
was markedly inhibited by ciprofloxacin, a drug which binds to
topoisomerase II. Etoposide (which inhibits topoisomerase II but
has no effect on tyrosine kinase activity) also caused an increase
in RINm5F cell death. Neither etoposide
nor ciprofloxacin altered the response to 5 mM NaF.
4. Pertussis toxin markedly enhanced the
extent of RINm5F cell death induced by NaF and this effect
was completely prevented by 25 microM genistein. The inhibition
caused by genistein was not affected by ciprofloxacin but was
reproduced by a structurally dissimilar tyrosine kinase inhibitor,
herbimycin A.
5. The results demonstrate that RINm5F beta-cells express a pertussis
toxin sensitive pathway that is anti-apoptotic. The activity of
this pathway is most evident in cells exposed to pro-apoptotic
stimuli where the effects of pertussis toxin can be blocked by
inhibitors of tyrosine kinase enzymes. A genistein-sensitive tyrosine
kinase does not appear to be involved in RINm5F cell survival
under basal conditions.
PMID:
11156568 [PubMed - indexed for MEDLINE]
Chinese
Journal of Endemiology 2000;19(2):96-8
Study
of the mechanism of neurone apoptosis
in rats from the chronic fluorosis
Lu X-H, Li G-S, Sun B
For Correspondence: Institute of Endemi c Diseases in Nornman
Bethune University of Medical Sciences, Changchun 130021, China
Objective: Study the mechanism of action chronic fluorosis in
neurones.
Methods:
Terminal deoxyribo-nucleotide transferase-mediated dUTP-biotin
nick end labeling (TUNEL) and flow cytometry (FCM) were used to
observe changes of apoptosis in cerebral cells in chronic fluorosis
in rats.
Results:
TUNEL results show non-random expression of DAB positive stain
apoptosis cells which appear only in the hippocampus CA4 region.
FCM re-sults show that the percentage of DNA fragmentation increased
markedly in the cerebral neurones of rats with chronic fluorosis
but not in different cerebral re-gions.
Conclusions:
There is a tendency for neurone apoptosis
in chronic fluorosis in rats. It is most evident with changes
in pathology. It is not likely that only one form of neurone damage
exist in the process of chronic fluorosis. There are recessive
changes and apoptosis in the process at the same time.
Fluoride induces apoptosis by caspase-3 activation in human
leukemia HL-60 cells.
Anuradha
CD, Kanno S, Hirano S.
Regional Environment Division, National Institute for Environmental
Studies, Tsukuba, Ibaraki, Japan.
Even though fluoride toxicity is increasingly
being considered to be important, very little information is available
on the mechanism of action of fluoride. In the present
study, the toxicity of fluoride on human leukemia (HL-60) cells
was investigated and the involvement of caspase-3 was also studied.
Fluoride induced apoptosis in HL-60 cells in a dose- and time-dependent
manner. Annexin staining and DNA ladder formation on agarose
gel electrophoresis further revealed that
HL-60 cells underwent apoptosis on exposure to 2-5 mM fluoride.
Western blotting using polyclonal anti-caspase-3 antibody and
mouse anti-human poly(ADP-ribose) polymerase (PARP) monoclonal
antibody was performed to investigate caspase-3 and PARP activity.
Fluoride led to the activation of caspase-3 which was evident
by the loss of the 32 kDa precursor and appearance of the 17 kDa
subunit. Furthermore, intact 116 kDa PARP was cleaved by fluoride
treatment as shown by the appearance of a cleaved 89 kDa fragment.
The results clearly suggest that fluoride
causes cell death in HL-60 cells by causing the activation of
caspase-3 which in turn cleaves PARP leading to DNA damage and
ultimately cell death.
PMID: 10959797 [PubMed - indexed for MEDLINE]
De novo expression
of the class-A macrophage scavenger receptor conferring resistance
to apoptosis in differentiated
human THP-1 monocytic cells.
Liao
HS, Matsumoto A, Itakura H, Pittman T, Kodama T, Geng YJ.
Cardiovascular and Pulmonary Research Institute, Allegheny University
of the Health Sciences, Pittsburgh, Pennsylvania 15212, USA.
The class-A
macrophage scavenger receptor (MSR) is a trimeric multifunctional
protein expressed selectively in differentiated monomyeloid
phagocytes which mediates uptake of chemically modified lipoproteins
and bacterial products. This study investigated whether MSR
plays a role in the regulation of apoptosis, a model of genetically
programmed cell death. De novo expression of MSR occurred in
human THP-1 monocytic cells differentiated with phorbol esters,
which activated a nuclear transcription factor binding to the
Ap1/ets-like domain of the MSR promoter. The phorbol ester-stimulated
THP-1 cells also expressed increased levels of the pro-apoptotic
gene products, caspase-3 and Fas ligand, but the cells exhibited
no change in apoptosis. Global activation
of GTP-binding proteins with fluoride anions triggered apoptosis
of THP-1 cells in a time- and concentration-dependent manner,
demonstrated by nuclear shrinkage and fragmentation and internucleosomal
DNA fragmentation. However, the MSR-expressing THP-1
macrophage-like cells showed a significant reduction in apoptosis
compared to undifferentiated control THP-1 cells, which produce
MSR at undetectable levels. Fluoride stimulation
also triggered apoptosis of human Jurkat T cells. Stimulation
with phorbol ester made no difference in apoptosis between treated
and untreated Jurkat cells. Finally, Chinese hamster ovary (CHO)
cells overexpressing the class-A MSR type I by cDNA transfection
showed markedly increased resistance to G-protein-coupled apoptosis.
Thus, de novo expression of MSR associated with monocyte maturation
into macrophages appears to confer the resistance of macrophages
to apoptotic stimulation by G-protein activation.
PMID: 10200575 [PubMed - indexed for MEDLINE]
Heterotrimeric
G proteins as fluoride targets in bone (review).
Susa
M.
Research Bone Metabolism, Novartis
Pharma AG, CH-4002 Basel, Switzerland.
Fluoride is an acknowledged bone anabolic agent. Nevertheless,
a narrow therapeutic window and the adverse effects at higher
therapeutic doses prevent broad clinical application of fluoride
for treatment of diseases of bone loss, such as osteoporosis.
The cellular and molecular mechanisms of fluoride action are
poorly understood. Recent advances in the elucidation of signal
transduction pathways induced by fluoride in osteoblastic cells
are reviewed. Fluoride and traces of aluminum form a complex,
fluoroaluminate, which stimulates cellular heterotrimeric G
proteins. Such complex can form in food, drinking water and
in the organism after administration of sodium fluoride. Fluoroaluminate
crosses the cell membrane and directly binds to the membrane-associated
inactive G alpha protein subunits. Within the G alpha subunit,
fluoroaluminate occupies the position next to GDP. The resulting
G alpha-GDP-AlF4- complex assumes an active state conformation,
which resembles that of G alpha-GTP complex. Under physiological
conditions, G alpha-GTP complex is formed upon activation of
seven transmembrane receptors that couple to heterotrimeric
G proteins. Both fluoroaluminate-activated and receptor-activated
G alpha subunits are capable of transmitting intracellular signals
that lead to cellular responses. In bone-forming cells osteoblasts,
fluoroaluminate stimulates pertussis toxin-sensitive G alpha
i proteins. G alpha I activation leads to the reduction in cAMP
(cyclic adenosine monophosphate) levels and to the activation
of mitogen activated protein kinases, Erks (extracellular signal-regulated
kinases) and p70 S6 kinase. These kinases are involved in the
regulation of gene transcription and protein syntheses. Fluoroaluminate
also stimulates pertussis toxin-insensitive proteins. Pertussis
toxin-insensitive G proteins, most likely from G alpha 12 class,
cause the activation of several cytoplasmic protein tyrosine
kinases [Src, Pyk2 (proline-rich tyrosine kinase 2), and Fak
(focal adhesion kinase)]. Activation of Erks can lead to osteoblast
proliferation and differentiation, while activation of Src,
Pyk2 and Fak can modulate the adhesion properties of osteoblasts.
Osteoblast adhesion may, in turn, influence differentiation,
migration, and apoptosis of these cells. The susceptibility
of osteoblasts to fluoroaluminate can be achieved by their specific
cellular context and by the rigidity of the surrounding bone
tissue. In particular, higher levels of G alpha I proteins and
of certain focal adhesion proteins are expressed by osteoblastic
rather than by fibroblastic cells. The rigidity of adhesion
substratum of osteoblasts may signal on its own and potentiate
the signaling by fluoroaluminate. The information on mechanisms
of intracellular signaling by fluoroaluminate
can be utilized to identify a fluoroaluminate mimic,
a drug that exhibits anabolic action on bone with a broader
therapeutic range and less adverse effects than fluoride.
Publication Types:
PMID:
9917518 [PubMed - indexed for MEDLINE]
Fluoride mediates apoptosis in osteosarcoma UMR 106 and
its cytotoxicity depends on the pH.
Hirano
S, Ando M.
Regional Environment Division, National Institute for Environmental
Studies, Tsukuba, Ibaraki, Japan.
Although an excess intake of fluoride has
been reported to cause skeletal fluorosis, very little is known
about the mechanism of adverse effects of
fluoride on bone. In the present study cytotoxic effects
of fluoride were studied using the
osteosarcoma cell line, UMR 106. The DNA ladder formation upon
agarose electrophoresis and terminal deoxynucleotidyl transferase-mediated
dUTP-biotin nick end-labeling (TUNEL) staining revealed that UMR
106 underwent apoptosis following exposure to 5 mM fluoride
for 8 h. On the other hand exposure to A23187, a calcium ionophore,
caused necrosis while co-exposure to fluoride
and A23187 inhibited fluoride-mediated
apoptosis in UMR 106. The proliferation of UMR 106 cells cultured
for 6 days in the presence of 0.5 mM fluoride
was significantly decreased compared to the control culture.
The cytotoxic effects of fluoride
were modulated by both the cell density and the pH of the culture
medium. The fluoride-induced viability
loss in UMR 106 was enhanced in culture of high cell-density and
inversely correlated with pH of the culture medium. Enhancement
of fluoride cytotoxicity at acidic
pH was also observed in rat alveolar macrophages and RAW 264,
a macrophage cell line. The results suggest
that fluoride-mediated apoptosis and culture conditions, including
pH of the medium, should be taken into consideration to evaluate
toxicity of fluoride in vitro.
PMID: 9458191
[PubMed - indexed for MEDLINE]
Exp
Cell Res 1996 Nov 25;229(1):69-76
Heterotrimeric G-proteins are implicated
in the regulation of apoptosis in pancreatic beta-cells.
Loweth
AC, Williams GT, Scarpello JH, Morgan NG.
Cellular Pharmacology Group, Department of Biological Sciences,
Keele University, Staffordshire, United Kingdom.
Recent studies have provided evidence that
apoptosis of pancreatic beta-cells is important in the early etiology
of both type I and type II diabetes mellitus. The
mechanisms responsible for induction of apoptosis are unknown,
but we present evidence that the signal transduction pathway controlling
the process in pancreatic beta-cells is regulated by G-proteins.
We have employed the global G-protein activator fluoride and show
that this agent induces apoptosis in clonal RINm5F pancreatic
beta-cells and also in the cells of normal rat islets of Langerhans.
The process is time and concentration dependent and may reflect
the formation of AIF4- since it was inhibited by the aluminum
chelator deferoxamine. Induction of apoptosis by fluoride was
confirmed by acridine orange staining of cell nuclei, by
electron-microscopic examination of chromatin condensation, and
by oligonucleosomal degradation of DNA. The
involvement of G-proteins was confirmed by culture of beta-cells
in the presence of pertussis toxin (PTX) prior to exposure to
fluoride. PTX did not affect the extent of cell death under
control conditions but it consistently, and markedly, enhanced
the response to fluoride.
The results demonstrate that apoptosis can be induced in pancreatic
beta-cells by sustained activation of a G-protein-dependent signaling
pathway(s) and they further suggest that a pertussis toxin-sensitive
G-protein is involved in attenuation of the response. Treatment
of RINm5F pancreatic beta-cells with dibutyrylcAMP resulted in
a dose-dependent, saturable increase in cell death, suggesting
that a sustained rise in intracellular cAMP may form part of the
effector system controlling apoptosis.
PMID:
8940250 [PubMed - indexed for MEDLINE]
Apoptotic
cell death following exposure to
fluoride in rat alveolar macrophages.
Hirano
S, Ando M.
Regional Environment Division, National Institute for Environmental
Studies, Ibaraki, Japan.
Since inhaled fluoride is implicated in
the acute respiratory failure, cytotoxic effects of fluoride
on alveolar macrophages, primary target cells of inhaled toxicants,
were investigated. The LC50 of sodium
fluoride was estimated to be 0.41 mM, while 1 mM sodium
chloride, bromide and iodide had virtually no effects on the
viability of alveolar macrophages. Photomicroscopic
observation revealed that nuclei of the fluoride-exposed alveolar
macrophages were fragmented. The ladder formation was
observed when DNA isolated from fluoride-exposed
alveolar macrophages was electrophoresed in agarose gel.
These results suggest that cytotoxicity of fluoride is associated
with apoptosis in rat alveolar macrophages.
PMID: 8825685 [PubMed - indexed for MEDLINE]
Cent
Eur J Public Health 1996;4 Suppl:6-10
The use
of isolated lung cells in in vitro pulmonary
toxicology: studies of DNA damage,
apoptosis and alteration of gene expression.
Schwarze
PE, Johnsen NM, Samuelsen JT, Thrane EV, Lund K, Lag M, Refsnes
M, Kongerud J, Becher R, Boe J, Holme JA, Wiger R.
Department of Environmental Medicine, National Institute of
Public Health, Oslo, Norway.
Isolated lung cells constitute a valuable system for studying
mechanisms involved in chemically induced toxicity in the lung.
Different lung cells isolated from various species may be studied.
Bronchiolar Clara and alveolar type 2 cells produce important
lung-specific proteins, hold a major role in the metabolism
of xenobiotics and serve as progenitor cells for other lung
cell types. They are possible target cells in lung carcinogenesis.
Alveolar macrophages play an important role in lung defence
and in inflammatory responses. In the present study we have
characterised chemically induced DNA damage, apoptosis, changes
in cell cycle progression, transformation and alterations in
gene expression in these specific lung cells isolated from rat,
rabbit and human. Major differences between the cell types and
the various species in the induction of DNA damage by chemicals
were found, as measured by the 32P-postlabelling and alkaline
filter elution techniques. Benzo(a)pyrene
and hydrogen fluoride were found to induce apoptosis in the
isolated cells as measured by microscopical analysis and flow
cytometry. The function of various important tissue-
or cell type specific proteins (CYP 2B1, Clara cell protein)
and/or cellular signal transduction pathways constitute important
targets that may be affected by exposure to toxic compounds.
Using immunological and molecular techniques the differential
expression of specific proteins/RNAs and their activity can
be studied. Among other proteins, c/ebp is involved in the regulation
of transcription at the end of signal pathways. The protein
is differentially expressed in rat lung cells and thus could
be suitable for studying differential toxic effects in various
lung cells. In humans, bronchoalveolar lavage (BAL) fluid from
human volunteers can be readily obtained and examined after
exposure to different chemical compounds. An
increase in the percentage of CD3-positive cells (T-lymphocytes)
was found after exposure to hydrogen fluoride. The number
of certain cell types and cytokines may be used to estimate
the degree of inflammatory reaction. In conclusion, the use
of in vitro data including the use of specific, primary human
lung cell types may contribute considerably to the quality of
risk assessment, together with in vivo data from animals and
man.
PMID: 9167048 [PubMed - indexed for MEDLINE]
Sodium
fluosilicate (also
known as Sodium
hexafluorosilicate)
-
Insecticide, Wood preservative, US EPA List 3 Inert -
CAS No. 16893-85-9
Full
free report available at: http://www.fluoride-journal.com/03-36-4/364-231.pdf
Fluoride
Vol. 36 No. 4 231-240 2003
- Research Report 231
THE
INFLUENCE OF SODIUM FLUORIDE AND SODIUM HEXAFLUOROSILICATE
ON HUMAN LEUKEMIC CELL LINES
Boguslaw
Machalinski (a), Magdalena Baskiewicz-Masiuk (a), Bogna
Sadowska (a), Anna Machalinska (b), Mariola Marchlewicz
(b), Barbara Wiszniewska (b), Iwona Stecewicz (a)
For Correspondence: Boguslaw Machalinski, MD, PhD., D.Sci.
(a) Department of General Pathology, Pomeranian Academy
of Medicine (PAM), Al. Powstancow Wlkp. 72, 70-111 Szczecin,
Poland. E-mail: machalin@sci.pam.szczecin.pl
(b) Department of Histology and Embryology, PAM, Al. Powstancow
Wlkp. 72, 70-111 Szczecin, Poland.
SUMMARY:
Although potential toxic effects of sodium fluoride on
early progenitor and stem cells have been reported previously,
surprisingly few investigations have examined the effects
of fluoride on human leukemic cells. To address this need,
four different human leukemic cell lines (HL-60, HEL,
TF-1, and K562) were exposed to increasing levels (0,
0.24, and 1.19 mM F) of two forms of fluoride: sodium
fluoride (NaF) and sodium hexafluorosilicate (Na2SiF6).
Because of its widespread use in water fluoridation, Na2SiF6
was investigated in addition to NaF.
The early response effect of Na2SiF6 was greater, and
in several cases significantly greater, than NaF on clonogenic
growth and the
induction of apoptosis in
all four cell lines. These
findings show that human leukemic cells can be influenced
and damaged by fluorine compounds.
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