Apoptosis: Adverse Effects
Fluorinated and Fluoride Pesticides

 
 

... 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.

Tetraconazole -Fungicide - CAS No. 112281-77-3
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 M) 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.
References:
1.HIRANO, S. & M. ANDO. 1996. Apoptotic cell death following exposure to fluoride in rat alveolar macrophages. Arch. Toxicol. 70: 249-251.
2.LOWETH, A., G.T. WILLIAMS, J.H. SCARPELLO & N.G. MORGAN. 1996. Heterotrimeric G-proteins are implicated in the regulation of apoptosis in pancreatic b-cells. Exp. Cell. Res. 229: 69-76.
3.THRANE, E.V., M. REFSNES, G.H. THORESEN, et al. 2001. Fluoride-induced apoptosis in epithelial lung cells involves activation of MAP kinases p38 and possibly JNK. Toxicol. Sci. 61: 83-91.[Free Full Text]

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
  • As cited and abstracted in Fluoride 2001; 34(1):82
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:

  • Review
  • Review, Academic
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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