* Laboratory of Comparative Carcinogenesis, National Cancer Institute at National Institute for Environmental Health Sciences, Mail Drop F0-09, Research Triangle Park, North Carolina 27709;
Laboratory of Pharmacology and Chemi-stry, NIEHS, Research Triangle Park, North Carolina 27709; and
University of Kansas Medical Center, Kansas City, Kansas 66160
Received December 12, 2000; accepted March 9, 2001
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key Words: arsenite; arsenate; acute toxicity; cDNA microarray; heme oxygenase-1.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Stress of various types has been proposed as one of the mechanisms for As-induced tissue damage and cell death (Barchowsky et al., 1996; 1999a
; Hei et al., 1998
; Keyse and Tyrrell, 1989
; Lee and Ho, 1995
). It has been shown that dimethylarsinic acid produces peroxyl radical (Yamanaka et al., 1990
), which may play a role in DNA damage and in tumor initiation or promotion (Yamanaka et al., 1990
, 1994, 1996
; Wei et al., 1999
). As(III) has high affinity for sulfhydryl groups, and As(V) mimics phosphate and is an uncoupler of oxidative phosphorylation (ATSDR, 1998; NRC, 1999
). Thus, both As(III) and As(V) could potentially produce stress, either directly or indirectly through uncoupling of mitochondrial oxidative phosphorylation, and/or increased cellular production of H2O2 (Barchowsky et al., 1996
; Hei et al., 1998
). A recent report shows As(III) stimulated superoxide formation in vascular endothelial cells through activation of NADPH oxidase, as evidenced by EPR spectrometry with the spin trap agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and increased extracellular accumulation of H2O2 (Barchowsky et al., 1999a
). However, little is known about the ability of inorganic arsenicals to generate reactive radical species and to produce stress in vivo.
Stress of various types and the subsequent restoration of cellular homeostasis after insults often lead to the activation or silencing of genes encoding for regulatory transcription factors, acute-phase proteins, antioxidant enzymes, and structural proteins (Dalton et al., 1999; Muller et al., 1997
). In this regard, As(III) is an effective inducer of a number of stress-related proteins including HSP32, HSP60, HSP70, HSP90, and metallothionein (Bauman et al., 1993
; Keyse and Tyrrell, 1989
; Kreppel et al., 1993
; NRC, 1999
). As(III) also activates transcription factors, such as the AP-1 complex and nuclear factor
B (NF-
B) (Barchowsky et al., 1996
; Cavigelli et al., 1996
), and produces DNA damage and alterations in gene expression in vitro (Hartwig, 1998
; Parrish et al., 1999
). However, the capability of As(III) and As(V) to modulate stress-related gene expression in intact animals is unknown.
This study was undertaken to define inorganic arsenic-induced stress-related gene expression in vivo, initially by screening with the Atlas Mouse Stress/Toxicology microarray, followed by analysis with the multiprobe RNase protection assay and Western blot analysis for specific genes or proteins. This is the first study to profile gene expression pattern associated with acute arsenic toxicity in vivo.
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Animals and treatments.
Adult male 129/Sv mice were obtained from Jackson Laboratories (Bar Harbor, ME), and maintained at 22 ± 1°C with a 12-h light/dark cycle in American Association for the Accreditation of Laboratory Animal Care (AAALAC)-accredited facilities at the University of Kansas Medical Center. Mice were allowed free access to standard rodent chow (Harlan Teklad 7001) and tap water. Male mice aged 68 weeks were used in this study. Mice were injected sc in the dorsal thoracic midline with 100 µmol/kg As(III), 300 µmol/kg As(V), or the same volume of saline (10 ml/kg). The dose selection was based on the considerations that high local As concentration is one of the mechanisms for cell death and arsenic carcinogenesis, such as in pulmonary cells in the proximity of inhaled As particles, and that a similar dose of asenicals was used in an attempt to detect free radical generation via ESR spin-trap techniques. Livers were removed 3 h later for total RNA isolation and protein preparation. The time-point selection was based on the consideration that the majority of gene alterations occur at 3 h after As insult, and was based on our preliminary studies (Liu et al., 2000a).
Microarray analysis.
The Atlas Mouse Toxicology/Stress cDNA expression microarray was performed according to manufacturer's instructions. Briefly, 1020 µg of total RNA was converted to [-32P]-dATP-labeled cDNA probe using MMLV reverse transcriptase and Atlas Mouse Stress CDS primer mix (Clontech, Palo Alto, CA). The 32P-labeled cDNA probe was purified using chroma spin-200 columns, denatured in 0.1 M NaOH, 10 mM EDTA at 68°C for 20 min, followed by neutralization with an equal volume of 1 M NaH2PO4 for 10 min. The membrane was prehybridized with Ultrahyb (Ambion, Austin, TX) for 3060 min at 42°C, followed by hybridization overnight at 42°C. Arrays were washed 2 times in 2 x SSC/0.1% SDS, 510 min each, and 2 times in 0.1 x SSC/0.1% SDS for 1530 min. The arrays were then sealed in a plastic bag, and exposed to a phosphoimage screen or X-ray film. The images were analyzed densitometrically using AtlasImage software (version 1.5). The gene expression intensities were normalized with the sum of 8 housekeeping genes on the array (40S ribosomal protein S29, 45-kDa calcium-binding protein, ß-actin, ornithine decarboxylase, myosin 1-
, G3PDH, hypoxantine-guanine phosphoribosyltransferase, and phospholipase A2) except for ubiquitin (the hybrid intensity of ubiquitin was saturated). Means and SE of 4 hybridizations were calculated for this analysis.
Multiprobe RNase protection assay.
The mouse Fos/Jun multiprobe template contains the AP-1 transcription factor complex: c-jun, junB, junD, c-fos, fosB, fra-1, and fra-2 (PharMingen #45357P). The multiprobe RNase protection assay was performed according to manufacturer's instructions. Briefly, 20 µg of total RNA was hybridized with 3P-UTP-labeled probes at 56°C overnight, followed by RNase A (33°C) and proteinase K (37°C) treatment for 45 min and 30 min, respectively. RNase-protected hybrids were extracted with phenol/chloroform/isoamyl alcohol (25:24:1), followed by ethanol precipitation and wash. The hybrids were then dissolved in QuickPoint sample loading buffer, denatured at 90°C for 3 min, and separated using QuickPoint DNA sequence gels (Novex, San Diego, CA). The hybrid intensity was detected by using a phosphoimager and quantified with ImageQuant software (Molecular Dynamics, Palo Alto, CA).
Western blot analysis.
Livers from control and arsenic-treated animals were homogenized (1:10, w:v) in 10 mM Tris-HCl, pH 7.4, containing freshly added protease inhibitors (100 µM PMSF, 2 µg/ml pepstain A, 2 µg/ml leupeptin, 2 µg/ml antipain, and 1 µg/ml aprotinin), and cytosols prepared by centrifugation at 15,000 x g for 10 min at 4°C. Protein concentrations were determined using the dye-binding assay (Bio-Rad, Hercules, CA). Total protein (2040 µg) was subjected to electrophoresis on Tris-glycine polyacrylamide precasted gels (420%) (Novex, San Diego, CA), followed by electrophoretic transfer to nitrocellulose membranes at 25V for 3 h. Membranes were blocked in 10% dried milk in TBST (15 mM Tris-HCl, pH 7.4, 150 mM NaCl, and 0.05% Tween 20) for 2 h at room temperature, followed by incubation with the primary antibody (1:2000) in 2% milk in TBST overnight at 4°C. After 4 washes with TBST, the membranes were incubated in secondary antibody (1:5000 to 1:10,000) for 60120 min. After 45 washes with TBST, proteins were visualized using ECL or SuperSignal chemiluminescent substrate (Pierce, Rockford, CA).
Statistics.
For cDNA microarray analysis, samples from groups of animals (45/group) were pooled, and microarrays were repeated 4 times using pooled samples from 2 separate animal experiments. Data represent the means ± SE of 4 hybridizations. Comparisons between control, As(III), and As(V) were made by ANOVA analysis followed by Ducan's test. The significance was set at p < 0.05.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
In contrast to the elevation of stress-related genes and DNA damage/repair-related genes, the expression of genes encoding for several drug-metabolizing enzymes was decreased (Fig. 3). As(III) treatment, but not As(V), suppressed the expression of NADPH cytochrome P-450 reductase (
50%), CYP3A13 (
35%), CYP2B9 (
30%), CYP21A1, and CYP1B1 (
30%). However, both As(III) and As(V) were inducers of CYP3A25. Surprisingly, As(V) produced a significant reduction of CYP7B1 expression, and markedly induced alcohol sulfotransferase (STA1) expression, effects not seen with As(III). In addition, As(III) (
30%) and As(V) (
20%) decreased the expression of peroxisome proliferator-activated receptor
, while the expressions of microsomal UDP-glucuronosyltransferases, hepatic flavin-containing monooxygenase, CYP1A1, CYP2E1, CYP2F2, liver carboxylesterase, and prostaglandin G/H synthase were not altered by either As(III) or As(V) treatments (data not shown). In general, As(III) at the dose of 100 µmol/kg produced greater alterations compared to 300 µmol/kg As(V) in the expression of drug-metabolizing genes.
RNase Protection Assay
Because the AP-1 complex is associated with stress-related gene activation, the effect of arsenicals on AP-1 complex activation was examined. The AP-1 complex consists of a heterodimer of jun-family transcription factors c-jun, junB, and junD, and a heterodimer of fos-family transcription factors c-fos, fos-B, Fra-1, and Fra-2. Figure 4 shows a representative AP-1 complex RNase protection assay (top), along with quantitation of individual gene band intensity (bottom). Both As(III) and As(V) produced marked activation of the AP-1 transcription complex. However, As(III) was less effective than As(V) in the induction of c-jun, while As(III) was more effective than As(V) in activation of c-fos, fosB, fra-1, and fra-2. Both As(III) and As(V) were equally effective inducers of junB and junD expression.
|
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Various stresses have been proposed as an important mechanism involved in arsenic toxicity and carcinogenesis. In cultured cells, As(III) increases the formation of fluorescent dichlorofluorecein by oxidation of the nonfluorescent form DCF-DAc (Barchowsky et al., 1996; Lee and Ho, 1995
). Reactive oxygen species scavengers such as superoxide dismutase (SOD), catalase, butylated hydroxytoluene, DMSO, or the antioxidant N-acetylcysteine, all have been reported to suppress arsenic-induced oxidative stress and its cytotoxic effects in cells (Barchowsky et al., 1999a
; Flora, 1999
; Gurr et al., 1998
; Lee and Ho, 1995
; Liu and Jan, 2000
). Reactive oxygen species are thought to participate in the mutagenecity of arsenic in mammalian cells (Hei et al., 1998
), in arsenic-induced DNA damage and perturbation of DNA repair processes (Hartwig, 1998
), and in arsenic-related Bowen's disease in humans, where positive 8-hydroxy-2'-deoxyguanosine immunostaining is observed (Matsui et al., 1999
). However, in the present study using intact animals, direct evidence for radical generation by inorganic arsenic in vivo was weak and inconclusive (data not shown).
Stress often leads to activation of transcription factors, such as the AP-1 complex, NF-B, and the metal-responsive transcription factor MTF-1 (Andrews, 2000
; Barchowsky et al., 1999a
; Cavigelli et al., 1996
; Dalton et al., 1999
; Kaltreider et al., 1999
). AP-1 is a heterodimer of the protein products of FOS and JUN immediate-early response gene family that controls the expression of many genes (Dalton et al., 1999
). As(III) has been shown to be a potent stimulator of AP-1, with induction of the immediate early genes c-fos and c-jun (Cavigelli et al., 1996
; Kaltreider et al., 1999
; Parrish et al., 1999
). In the present study, both As(III) and As(V) were effective activators of the AP-1 complex, as determined by multiprobe RNase protection assay using the mouse Fos/Jun template and Western blot analysis. As(III) was more effective than As(V) in the induction of c-fos, fosB, fra-1, and fra-2. It should be noted that the dose of As(V) used in the present study was 3 times higher than the dose of As(III). At the same dose, As(III) but not As(V) has been shown to be an effective stimulator of the AP-1 complex (Cavigelli et al., 1996
). In addition to activation of the AP-1 transcription complex, both As(III) and As(V) also increased NF-
B p65 protein level, as revealed by Western blot analysis, supporting the observation that acute arsenic induces oxidative stress and activates NF-
B in cells (Barchowsky et al., 1996
; Kaltreider et al., 1999
; Tully et al., 2000
). MTF-1, a 6 zinc-finger metal-responsive transcription factor regulating metallothionein gene expression in response to oxidative stress (Andrews, 2000
), was increased by both As(III) and As(V). MTF-1 activation accounts for the induction of metallothionein by arsenicals seen in mice in a previous study (Kreppel et al., 1993
) and in the present study by Western blot analysis.
Induction of HO-1 is a hallmark of As-induced stress (Applegate et al., 1991; Keyse and Tyrrell, 1989
; Medzel et al., 1998
; Parrish et al., 1999
). In the present study, marked induction of HO-1 (also called HSP32) was observed after both As(III) and As(V) treatments. Other stress-related heat-shock proteins such as HSP60, HSP70, and HSP90 were also induced, as revealed by cDNA microarray and Western blot analysis. Induction of HO-1 by arsenic is thought to be mediated through activation of the MAP kinase pathway (Elbirt et al., 1998
). The MAP kinase pathway activation by arsenic is also involved in stress-induced cell death and apoptosis (Barchowsky et al., 1999b
; Samet et al., 1998
). In the present study, MAP kinase-activated protein kinase 2 (MAPKPK2) was also increased by As(III), supporting the notion that activation of the MAP kinase pathway is involved in acute As toxicity.
Both As(III) and As(V) produced increases in DNA-damage/repair-related gene expression, and more intense increases were seen in As(III)-treated animals in the present study. For example, the DNA-damage inducible proteins GADD45 and GADD153, and DNA mismatch repair protein PMS2 were all greatly induced in As(III)-treated mice as compared to As(V)-treated mice. As(III) is known to produce DNA-protein crosslinks (Gebel et al., 1998), DNA strand breaks, micronuclei (Lynn et al., 1998
), and alterations in DNA repair enzymes (Hartwig, 1998
). In this study, DNA ligase-1 and DNA excision repair protein ERCC1 were similarly increased by As(III) and As(V) treatment. In addition, many other DNA damage/repair genes also increased, suggesting cellular response to arsenic-induced DNA damage. DNA damage could play an important role in acute arsenic-induced cell death, and in the etiology of many human cancers (Marnett, 2000
; Tully et al., 2000
). The present studies support the idea that arsenic-induced DNA damage is an important mechanism involved in acute arsenic toxicity and carcinogenesis.
A number of constitutively expressed cytochrome P450 enzymes in mouse liver were suppressed with acute arsenic treatment. In the present study, the expression of genes encoding for drug-metabolizing enzymes such as CYP1B1, CYP2B9, CYP7A1, CYP7B1, CYP3A11, and cytochrome P450 reductase were all suppressed, while the expression of other drug-metabolizing enzymes was minimally affected. Compared to marked induction of acute-phase proteins, the reduction of these constitutively expressed proteins was not appreciable, possibly due to the short-term period of arsenic exposure (3 h), because notable downregulation of constitutive proteins usually occurs 424 h after oxidative stress insults (Dalton et al., 1999). Surprisingly, As(V) administration dramatically induced alcohol sulfotransferase (SAT1, more than 50x), while As(III) had no effect on this enzyme. The significance of SAT1 induction by As(V) is not immediately clear, and requires further investigation.
Caspase activation has been proposed to play a role in arsenic-induced apoptosis (Chen et al., 1998). In the present study, caspase-1 was activated by both As(III) and As(V) (Figure 5
). Induction of inflammatory cytokines is another important aspect of arsenic toxicity. As(III) produces overexpression of TGF-
, TNF-
, and GM-CSF in Tg.AC mouse skin and in As-exposed human skin samples (Germolec et al., 1998
), and As(III) produces overexpression of IL-1
in murine keratinocytes (Corsini et al., 1999
). Serum levels of TNF-
, IL-1ß, and IL-6 are also increased following chronic exposure of mice to As(III) or As(V) (Liu et al., 2000b
). In the present study, As(III) at the dose of 100 µmol/kg was more effective than As(V) at the dose of 300 µmol/kg in increasing the expression of MIP-2 (an important mediator of neutrophil recruitment) and TNF-
(an important cytokine involved in the initiation of oxidative damage and cell death) in the mouse liver, suggesting that the involvement of proinflammatory cytokines could also be an important component of arsenic-induced stress and acute toxicity.
In summary, the results of the present study demonstrate that acute inorganic arsenic administration in vivo results in alterations in the expression of genes related to stress, DNA damage, transcription factor activation, and cytokine production. These gene alteration profiles associated with acute arsenic exposure would add to our understanding of acute arsenic poisoning and toxicity.
![]() |
ACKNOWLEDGMENTS |
---|
![]() |
NOTES |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Applegate, L. A., Luscher, P., and Tyrrell, R. M. (1991). Induction of heme oxygenase: A general response to oxidant stress in cultured mammalian cells. Cancer Res. 51, 974978.[Abstract]
ATSDR (2000). Toxicological profile for arsenic. Agency for Toxic Substances and Disease Registry. Atlanta, U.S. Department of Health and Human Services.
Barchowsky, A., Dudek, E. J., Treadwell, M. D., and Wetterhahn, K. E. (1996). Arsenic induces oxidant stress and NF-kB activation in cultured aortic endothelial cells. Free Radic. Biol. Med. 21, 783790.[ISI][Medline]
Barchowsky, A., Klei, L. R., Dudek, E. J., Awartz, H. M., and James, P. E. (1999a). Stimulation of reactive oxygen, but not reactive nitrogen species, in vascular endothelial cells exposed to low levels of arsenite. Free Radic. Biol. Med. 27, 14051412.[ISI][Medline]
Barchowsky, A., Roussel, R. R., Klei, L. R., James, P. E., Ganju, N., Smith, K. R., and Dudek, E. J. (1999b). Low levels of arsenic trioxide stimulate proliferative signals in primary vascular cells without activating stress effector pathways. Toxicol. Appl. Pharmacol. 159, 6575.[ISI][Medline]
Bauman, J. B., Liu, J., and Klaassen, C. D. (1993). Production of metallothionein and heat-shock proteins in response to metals. Fundam. Appl. Toxicol. 21, 1522.[ISI][Medline]
Cavigelli, M., Li, W. W., Lin, A., Su, B., Yoshioka, K., and Karin, M. (1996). The tumor promoter arsenite stimulates AP-1 activity by inhibiting a JNK phosphatase. EMBO J. 15, 62696279.[Abstract]
Chen, Y. C., Lin-Shiau, S. Y., and Lin, J. K. (1998). Involvement of reactive oxygen species and caspase 3 activation in arsenite-induced apoptosis J. Cell Physiol. 177, 324333.[ISI][Medline]
Corsini, E., Asti, L., Viviani, B., Marinovich, M., and Galli, C. L. (1999). Sodium arsenite induces overproduction of interleukin-a alpha in murine keratinocytes: Role of mitochondria. J. Invest. ermatol. 113, 760765.
Dalton, T. P., Shertzer, H. G., and Puga, A. (1999). Regulation of gene expression by reactive oxygen. Ann. Rev. Pharmacol. Toxicol. 39, 67101.[ISI][Medline]
Elbirt, K. K., Whitmarsh, A. J., Davis, R. J., and Bonkovsky, H. L. (1998). Mechanism of sodium arsenite-mediated induction of heme oxygenase-1 in hepatoma cells. Role of mitogen-activated protein kinases. J. Biol. Chem. 273, 89228931.
Flora, S. J. S. (1999). Arsenic-induced oxidative stress and its reversibility following combined administration of N-acetylcysteine and meso 2,3-dimercaptosuccinic acid in rats. Clin. Exp. Pharmacol. Physiol. 26, 865869.[ISI][Medline]
Gebel, T., Birkenkamp, P., Luthin, S., and Dunkelberg, H. (1998). Arsenic(III), but not antimony(III), induces DNA-protein crosslinks. Anticancer Res. 18, 42534257.[ISI][Medline]
Germolec, D. R., Spalding, J., Yu, H. S., Chen, G. S., Simeonova, P. P., Humble, M. C., Bruccoleri, A., Boorman, G. A., Foley, J. F., Yoshida, T., and Luster, M. I. (1998). Arsenic enhancement of skin neoplasia by chronic stimulation of growth factors. Am. J. Pathol. 153, 17751785.
Gurr, J. R., Liu, F., Lynn, S., and Jan, K. Y. (1998). Calcium-dependent nitric oxide production is involved in arsenite-induced micronuclei. Mutat. Res. 416, 137148.[ISI][Medline]
Hamadeh, H. K., Vargas, M., Lee, E., and Menzel, D. B. (1999). Arsenic disrupts cellular levels of p53 and mdm2: A potential mechanism of carcinogenesis. Biochem. Biophys. Res. Commun. 263, 446449.[ISI][Medline]
Hartwig, A. (1998). Carcinogenicity of metal compounds: Possible role of DNA repair inhibition. Toxicol. Lett. 103, 235239.[ISI]
Hei, T. K., Liu, S. X., and Waldren, C. (1998). Mutagenicity of arsenic in mammalian cells: Role of reactive oxygen species. Proc. Natl. Acad. Sci. U.S.A. 95, 81038107.
Kaltreider, R. C., Pesce, C. A., Ihnat, M. A., Lariviere, J. P., and Hamilton, J. W. (1999). Differential effects of arsenic(III) and chromium(V) on nuclear transcription factor binding. Mol. Carcinogenesis 25, 219229.[ISI][Medline]
Keyse, S. M., and Tyrrell, R. M. (1989). Heme oxygenase is the major 32-Kda stress protein induced in human skin fibroblasts by UVA radiation, hydrogen peroxide and sodium arsenite. Proc. Natl. Acad. Sci. U.S.A. 86, 99103.[Abstract]
Kreppel, H., Bauman, J. W., Liu, J., McKim, J. M., Jr., and Klaassen, C. D. (1993). Induction of metallothionein by arsenicals in mice. Fundam. Appl. Toxicol. 20, 184189.[ISI][Medline]
Lee, T.-C., and Ho, I.-C. (1995). Modulation of cellular antioxidant defense activities by sodium arsenite in human fibroblasts. Arch. Toxicol. 69, 498504.[ISI][Medline]
Liu, F., and Jan, K. Y. (2000). DNA damage in arsenite- and cadmium-treated bovine aortic endothelial cells. Free Radic. Biol. Med. 28, 5563.[ISI][Medline]
Liu, J., Kadiiska, M., Liu, Y., Qu, W., Mason, R. P., and Waalkes, M. P. (2000a). Acute arsenic induced free radical production and oxidative stress-related gene expression in mice. Toxicol. Sci. 54(Suppl.), 1314.
Liu, J., Liu Y., Goyer, R. A., Achanzar, W., Waalkes, M. P. (2000b). Metallothionein-I/II null mice are more sensitive than wild-type mice to the hepatotoxic and nephrotoxic effects of chronic oral or injected inorganic arsenicals. Toxicol Sci. 55, 460467.
Lynn, S., Shiung, J.-N., Gurr, J.-R., and Jan, K. Y. (1998). Arsenite stimulates poly (ADP-ribosylation) by generation of nitric oxide. Free Radic. Biol. Med. 24, 442449.[ISI][Medline]
Marnett, L. J. (2000). Oxyradicals and DNA damage. Carcinogenesis 21, 361370.
Matsui, M., Nishigori, C., Toyokuni, S., Takada, J., Akaboshi, M., Ishikawa, M., Imamura, S., and Miyachi, Y. (1999). The role of oxidative DNA damage in human arsenic carcinogenesis: Detection of 8-hydroxy-2'-deoxyguanosine in arsenic-related Bowen's disease. J. Invest. Dermatol. 113, 2631.
Medzel, D. B., Rasmussen, R. E., Lee, E., Meacher, D. M., Said, B., Hamadeh, H., Vargas, M., Greene, H., and Roth, R. N. (1998). Human lymphocyte heme oxygenase 1 as a response biomarker to inorganic arsenic. Biochem. Biophys. Res. Commun. 250, 653656.[ISI][Medline]
Muller, J. M., Rupec, R. A., and Baeuerle, P. A. (1997). Study of gene regulation by NF-B and AP-1 in response to reactive oxygen intermediates. Methods 11, 301312.[ISI][Medline]
NRC (1999). Arsenic in Drinking Water. National Research Council. National Academy Press, Washington, D.C.
Parrish, A. R., Zheng, X. H., Turney, K. D., Younis, H. S., and Gandolfi, A. J. (1999). Enhanced transcription factor DNA binding and gene expression induced by arsenite or arsenate in renal slices. Toxicol. Sci. 50, 98105.[Abstract]
Samet, J. M., Graves, L. M., Quay, J., Dailey, L. A., Devlin, R. B., Ghio, A. J., Wu, W., Bromberg, P. A., and Reed, W. (1998). Activation of MAPKs in human bronchial epithelial cells exposed to metals. Am. J. Physiol. 275, L551L558.[ISI][Medline]
Tully, D. B., Collins, B. J., Overstreet, J. D., Smith, C. S., Dinse, G. E., Mumtaz, M. M., and Chapin, R. E. (2000). Effects of arsenic, cadmium, chromium, and lead on gene expression regulated by a battery of different promoters in recombinant HepG2 cells. Toxicol. Appl. Pharmacol. 168, 7990.[ISI][Medline]
Wei, M., Wanibuchi, H., Yamamoto, S., Li, W., and Fukushima, S. (1999). Urinary bladder carcinogenicity of dimethylarsinic acid in male F344 rats. Carcinogenesis 20, 18731876.
Yamanaka, K., Hoshino, M., Okamoto, M., Sawamura, R., Hasegawa, A., and Okada, S. (1990). Induction of DNA damage by dimethylarsine, a metabolite of inorganic arsenics, is for the major part likely due to its peroxyl radical. Biochem. Biophys. Res. Commun. 168, 5864.[ISI][Medline]
Yamanaka, K., Ohtsubo, K., Hasegawa, A., Hayashi, H., Ohji, H., Kanisawa, M., and Okada, S. (1996). Exposure to dimethylarsinic acid, a main metabolite of inorganic arsenics, strongly promotes tumorigenesis initiated by 4-nitroquinoline 1-oxide in the lungs of mice. Carcinogenesis 17, 767770.[Abstract]
Yamanaka, K., and Okada, S. (1994). Induction of lung-specific DNA damage by metabolically methylated arsenics via the production of free radicals. Environ. Health Perspect. 102(Suppl.), 3740.[ISI][Medline]