Cancer Research SABCS Jordan
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Cancer Research Clinical Cancer Research
Cancer Epidemiology Biomarkers & Prevention Molecular Cancer Therapeutics
Molecular Cancer Research Cancer Prevention Research
Cancer Prevention Journals Portal Cancer Reviews Online
Annual Meeting Education Book Meeting Abstracts Online
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Salnikow, K.
Right arrow Articles by Costa, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Salnikow, K.
Right arrow Articles by Costa, M.
[Cancer Research 60, 3375-3378, July 1, 2000]
© 2000 American Association for Cancer Research

Advances in Brief

Carcinogenic Metals Induce Hypoxia-inducible Factor-stimulated Transcription by Reactive Oxygen Species-independent Mechanism1

Konstantin Salnikow2, Weicheng Su, Mikhail V. Blagosklonny and Max Costa

Nelson Institute of Environmental Medicine and Kaplan Comprehensive Cancer Center, New York University School of Medicine, New York, New York 10016 [K. S., W. S., M. C.], and Medicine Branch, National Cancer Institute, NIH, Bethesda, Maryland 20892 [M. V. B.]


   ABSTRACT
Top
 ABSTRACT
Introduction
 Materials and Methods
 Results
 Discussion
 REFERENCES
 
Nickel (Ni2+) and cobalt (Co2+) mimic hypoxia and were used as a tool to study the role of oxygen sensing and signaling cascades in the regulation of hypoxia-inducible gene expression. These metals can produce oxidative stress; therefore, it was conceivable that reactive oxygen species (ROS) may trigger signaling pathways resulting in the activation of the hypoxia-inducible factor (HIF)-1 transcription factor and up-regulation of hypoxia-related genes. We found that the exposure of A549 cells to Co2+ or Ni2+ produced oxidative stress, and although Co2+ was a more potent producer of ROS than Ni2+, both metals equally increased the expression of Cap43, a hypoxia-regulated gene. The coadministration of hydrogen peroxide with metals induced more ROS; however, this did not further increase the expression of Cap43 mRNA. The free radical scavenger 2-mercaptoethanol completely suppressed ROS generation by CoCl2 and NiCl2 but did not diminish the induced Cap43 gene expression. The activity of the HIF-1 transcription factor as assessed in transient transfection assays was stimulated by Ni2+, hypoxia, and desferrioxamine, but this activation was not diminished when oxidative stress was attenuated nor was HIF-dependent transcription enhanced by hydrogen peroxide. We conclude that ROS are produced during the exposure of cells to metals that mimic hypoxia, but the formation of ROS was not involved in the activation of HIF-1-dependent genes.


   Introduction
Top
 ABSTRACT
 Introduction
Materials and Methods
 Results
 Discussion
 REFERENCES
 
Hypoxia results in the coordinated up-regulation of numerous genes involved in glucose transport, glycolysis, erythropoiesis, angiogenesis, and catecholamine metabolism that is mediated by the HIF3 -1 transcription factor (1 , 2) . Whereas HIF-1{alpha} protein was expressed at low levels due to its rapid degradation, it was accumulated following hypoxic stress through inhibition of its proteasomal degradation (3) .

The transition metals (Co2+, Ni2+, and Mn2+) and iron chelater (DFX) also up-regulated HIF-1 and HIF-1-dependent transcription, but the mechanism involved in the metal activation is unknown (4, 5, 6) . There are two groups of models that may explain HIF-1 activation (1 , 7) . First, that sensing of the low oxygen state (hypoxia) involves an iron-containing flavoheme protein. It is possible that transition metals by substituting for iron in this sensor activate a signaling cascade leading to HIF-1{alpha} stabilization (8 , 9) . Another model suggested that the modulation of endogenous H2O2 and O2- levels while O2 concentration declines provided a redox signal for HIF-1 induction (10, 11, 12) .

Co2+ and Ni2+ increased the generation of oxidative stress in cells and increased the level of ROS (13, 14, 15, 16) . Although the increase of ROS under a state of hypoxic stress occurred after exposure to both metals and hypoxia, it was not clear whether this was the stimulus for a hypoxic gene response.

Recently, we have cloned a new human gene, Cap43, based on its high inducibility by Ni2+ (17) . This gene was found to be transcriptionally up-regulated by hypoxia, Ni2+, or Co2+ through HIF-1-dependent pathways (18) . Because these transition metals generate ROS, we investigated whether ROS played a role in the activation of hypoxic genes by metals. 2-Mercaptoethanol, a free radical scavenger, attenuated ROS but did not prevent the induction of Cap43 by Ni2+, Co2+, or hypoxia. The exposure of cells to H2O2 elevated ROS but did not induce Cap43 gene expression. Additionally, the Ni or hypoxia-related enhanced expression of a HIF-1-dependent reporter plasmid, HRE-Luc, was not attenuated by 2-mercaptoethanol. We concluded that free radicals accumulation after Ni2+ or Co2+ exposure in A549 cells did not participate in HIF-1 activation or in the up-regulation of Cap43 gene expression.


   Materials and Methods
Top
 ABSTRACT
 Introduction
 Materials and Methods
Results
 Discussion
 REFERENCES
 
Cell Culture.
Human A549 lung cells (CCL 185) and human umbilical vascular endothelial cells (CRL 1730) were purchased from American Type Culture Collection (Manassas, VA). Cells were maintained in F-12K medium (Life Technologies, Inc., Gaithersburg, MD) supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin (equivalent to 100 units/ml and 100 µg/ml, respectively) at 37°C as monolayers in a humidified atmosphere containing 5% CO2.

Exposure of Cells to Metals and Other Agents.
NiCl2 and CoCl2 were purchased from Alfa Aesar (Ward Hill, MA). H2O2, 2-mercaptoethanol, and vitamin E were obtained from Sigma Chemical Co. (St. Louis, MO). All metals were dissolved in distilled water at high concentrations and then filtered through a sterile, pathogen-free nylon filter (pore size: 0.22 mm; MSI Inc., MA). A freshly prepared stock metal solution was mixed with F12K at various concentrations. Vitamin E was dissolved in DMSO. 2-Mercaptoethanol was dissolved directly into F12K medium.

Northern Blot Analysis.
Total RNA was extracted from cells immediately following chemical/metal exposure using the TRIzol RNA isolation system (Life Technologies, Inc.), and 15 µg total RNA were separated by electrophoresis in 1.2% agarose/formaldehyde gels. Cap43 and actin probes were labeled with [32P]-{alpha}-dCTP using a Random Primed DNA Labeling Kit (Boehringer Mannheim). The membrane was prehybridized for 2 h, hybridized with the probe of interest for 2 h, and then washed and exposed to film (Eastman-Kodak, Rochester, NY) or phosphorscreen.

Measurement of Intracellular ROS Generation and Data Analysis.
The level of intracellular ROS was measured by the change in fluorescence resulting from oxidation of DCFH-DA (Molecular Probes, Eugene, OR). After the dye had entered cells, the acetate group on DCF-DA was cleaved by intracellular esterases, thereby trapping the nonfluorescent (DCFH). When DCFH was oxidized by ROS inside the cell it was converted into fluorescent DCF (19) . DCFH-DA was dissolved in DMSO to a final concentration of 20 mM before use. For the measurement of ROS, cells were incubated with 10 µM DCF-DA at 37°C for 30 min. The excess DCFH-DA was washed with F12K media prior to metal exposure. The cells were subsequently plated at a density of 1 x 104 cells per well into Costar 96-well plates with a clear bottom (Costar Corp., Cambridge, MA). The following day, metals or other chemicals were added to each well for a time period indicated in the figure or table legends. The intensity of fluorescence was recorded using a 37°C prewarmed fluorescent microplate reader, HTS 7000 (Perkin-Elmer Corp., Norwalk, CT), with an excitation filter of 485 nm and an emission filter 535 nm. The ROS level was calculated as a ratio: ROS = mean intensity of exposed cells:mean intensity of unexposed cells. The signals obtained from six separate wells were used to assess ROS for each treatment. The mean value for an individual group was obtained using the StatView or MiniTab software. Before performing the statistical analysis, the coefficient of variance for each treatment or time point was assessed to screen the distribution of data points within each treatment group. The data set was plotted with mean (ROS ratio) ± SE over time to compare the effects of different metals and chemicals. ANOVA was used to assess treatment effects, and a P < 0.05 was considered statistically significant for all tests.

Transient Transfection Assay.
Cells (5 x 104 per well) were plated in 24-well plates (Costar, Acton, MA). The next day, cells were transfected with HRE-Luc plasmid in the presence of Lipofectamine (Life Technologies, Inc.), according to the manufacturer’s recommendations. Six h later, the medium was changed and cells were grown for an additional 24 h. The cells were lysed and analyzed for luciferase activity using a TopCount Luminometer (Packard Instrument, Meriden, CT).


   Results
Top
 ABSTRACT
 Introduction
 Materials and Methods
 Results
Discussion
 REFERENCES
 
ROS in A549 Cells Exposed to Ni2+ and Co2+.
It has been previously shown that Co2+ and Ni2+ produced ROS in biological systems (13 , 16 , 20) . However, comparative measurement of ROS levels resulting from exposure to each metal in the same cell type was not determined. To evaluate the induction of ROS in Ni- or Co-treated cells, A549 cells preloaded with DCFH-DA were exposed to either NiCl2 or CoCl2. DCFH-DA is commonly used to detect the generation of reactive oxygen intermediates in cells (19) . DCFH-DA has been recently highlighted as an extremely useful reagent for assessing the overall oxidative stress phenomena during hypoxia (11) . Fig. 1, A and BCitation , shows the time- and concentration-dependent increase in ROS generation when A549 cells were incubated with various concentrations of Ni2+ and Co2+. A 5-fold increase of ROS above basal levels was found in cells exposed for 4 h to 300 µM Co (Fig. 2A)Citation . There was also a significant difference in ROS production between exposure to 100 µM or 300 µM Co, suggesting dose dependency. However, in Ni2+-exposed cells, much lower amounts of ROS were detected (Figs. 1BCitation and 2B)Citation . There were only small differences in ROS levels in cells treated with 250 µM, 500 µM, or 1000 µM Ni2+ (Fig. 1B)Citation . It should be noted that the range of Ni2+ and Co2+ exposure conditions reflect equivalent levels of cytotoxicity for the A549 cells (data not shown).



View larger version (36K):
[in this window]
[in a new window]
[Download PPT slide]
  		Fig. 1. The effect of Co2+ and Ni2+ on ROS generation and Cap43 gene expression. A, intensity of DCF fluorescence in A549 cells exposed to different concentrations of CoCl2. Cells were exposed to 100, 200, and 300 µM CoCl2 for 45 min. The intensity of DFC fluorescence was measured every 2 min, and data represent mean values of eight independent measurements for the same time point ± single SD. B, intensity of DCF fluorescence in A549 cells exposed to various concentrations of NiCl2. Cells were exposed to 250, 500, and 1000 µM NiCl2 for 45 min. The intensity of DFC fluorescence was measured and evaluated as described in A. C, Cap43 expression in A549 cells exposed to various concentrations of CoCl2. Cells were treated with 100, 200, and 300 µM CoCl2 for 20 h. Fifteen micrograms of total RNA were isolated and subjected to a Northern blot analysis. The level of Cap43-specific mRNA expression was measured by hybridization, and the mean ± SD for several experiments was quantitated using PhosphorImager Storm 860 and ImageQuant software. D, Cap43 expression in A549 cells exposed to various concentrations of NiCl2. Cells were treated with 250, 500, and 1000 µM NiCl2 for 20 h. Fifteen micrograms of total RNA were isolated and subjected to a Northern blot analysis. The level of Cap43-specific mRNA expression was measured by hybridization, and the mean ± SD for several experiments was quantitated using PhosphorImager Storm 860 and ImageQuant software.

 


View larger version (23K):
[in this window]
[in a new window]
[Download PPT slide]
  		Fig. 2. The effect of 2-mercaptoethanol or H2O2 on metal-induced ROS generation. A, intensity of DCF fluorescence in A549 cells exposed to 300 µM CoCl2 alone or in combination with 2-mercaptoethanol, vitamin E, or H2O2. ROS species was quantified by DCF fluorescence. The measurements were done at 0.5, 1, 3, and 4 h, and data represent mean values of six independent measurements for the same time point ± single SD, as described in "Materials and Methods." B, DCF fluorescence in A549 cells exposed to 1000 µM NiCl2 alone or in combination with 2-mercaptoethanol, vitamin E, or H2O2. ROS species was quantified by DCF fluorescence. The measurements were done at 0.5, 1, 3, and 4 h, and data represent mean values of six independent measurements for the same time point ± single SD, as described in "Materials and Methods."

 
We also assessed Cap43 gene expression following exposure of A549 cells to 100 µM, 200 µM, and 300 µM Co2+ or 250 µM, 500 µM, and 1000 µM Ni2+ (Fig. 1, C and D)Citation . No association was found between the level of ROS in cells, as determined by DCF fluorescence shown in Fig. 1, A and BCitation , and Cap43 gene expression. For example, ROS levels were not different in cells treated with 500 µM or 1000 µM of Ni2+, however, the expression of Cap43 mRNA differed by 2.8-fold for these two Ni concentrations. In cells treated with 100 µM Co2+ very few ROS were detected, however, the expression of Cap43 increased 4-fold above basal levels. Additionally, exposure of A549 cells for 20 h to 300 µM Co2+ produced much higher levels of ROS compared with 1000 µM Ni2+ exposure (data not shown), yet the level of Cap43 mRNA were comparable in both situations (Fig. 1, C and D)Citation .

The Effect of Free Radical Scavengers on ROS Production and Cap43 Gene Expression.
To evaluate whether ROS participate in signaling pathways involved in the activation of hypoxia-inducible genes, we used two scavengers of free radicals, the monothiol-reducing agent 2-mercaptoethanol and vitamin E. 2-Mercaptoethanol seemed to be a more efficient scavenger of ROS produced by Ni2+ or Co2+ compared with vitamin E (Fig. 2, a and b)Citation . In fact, vitamin E was not very efficient in scavenging ROS in Ni2+-exposed cells and was only partially effective in Co2+-exposed cells. The addition of 2 mM 2-mercaptoethanol to Ni2+- or Co2+-exposed cells completely eliminated the DCF-detectable free radicals produced by the metals (Fig. 2, A and B)Citation . 2-Mercaptoethanol alone, or in combination with Ni2+, Co2+, or hypoxia did not affect Cap43 gene expression but diminished detectable ROS levels (see above; Fig. 3Citation ). The addition of H2O2 alone or in combination with Ni2+, Co2+, or hypoxia similarly had no effect on Cap43 gene expression (Fig. 3)Citation despite somewhat augmenting the levels of ROS in Ni-exposed cells (Fig. 2, A and B)Citation . These data suggested that the up-regulation of Cap43 gene expression by metals that induce hypoxia-related genes was not linked with enhanced ROS formation in A549 cells.



View larger version (51K):
[in this window]
[in a new window]
[Download PPT slide]
  		Fig. 3. The effect of 2-mercaptoethanol or H2O2 on metal- or hypoxia-driven Cap43 gene expression. A549 cells were exposed to Ni, Co, or hypoxia alone or in combination with 2 mM 2-mercaptoethanol or 500 µM H2O2 for 20 h. Fifteen micrograms of total RNA were isolated and subjected to a Northern blot analysis. The bottom lane shows the expression of ß-actin in the same sample.

 
The Effect of Free Radical Scavengers on HIF-1 Reporter Plasmids.
The augmentation of Cap43 gene expression by hypoxia or metals was dependent on HIF-1 because this augmentation was absent in HIF-1{alpha}-deficient cells (18) . However, hypoxic conditions stabilized Cap43 mRNA. To study whether there was a direct effect of ROS on HIF-1 activity, we used transient transfection assay and a HIF-1-dependent reporter plasmid, HRE-Luc. This plasmid contained three HIF-1-responsive elements of the iNOS promoter (6) . Hypoxia or Ni2+ enhanced the expression of the reporter plasmid, as did DFX, which also simulated hypoxic-related genes. The addition of 500 µM H2O2 or 2 mM 2-mercaptoethanol did not affect the enhancement in reporter plasmid activity attributed to either Ni2+ or hypoxia (Fig. 4)Citation . Neither H2O2 nor 2-mercaptoethanol alone was effective in stimulating HRE-Luc expression (Fig. 4)Citation .



View larger version (20K):
[in this window]
[in a new window]
[Download PPT slide]
  		Fig. 4. HIF-1-dependent transcription in A549 cells exposed to Ni, DFX, or hypoxia. A549 cells were transfected with 1 µg of HRE-Luc plasmid. In some instances, transfected cells were also treated with 1 mM nickel chloride, 260 µM DFX, hypoxia (1% O2), 2 mM 2-mercaptoethanol, or 500 µM H2O2 for 16 h. Results are presented as a ratio of HRE-Luc expression:CMV-Luc expression in the same cells.

 

   Discussion
Top
 ABSTRACT
 Introduction
 Materials and Methods
 Results
 Discussion
REFERENCES
 
Current models of hypoxic response are based on changes in oxygen sensor or on the production of ROS during hypoxia. Although disputed, ROS are produced during hypoxia, but non-ROS-dependent oxygen sensing may also exist. Ni2+ or Co2+ produce ROS in cells, but they may also substitute for iron in oxygen sensing. In this situation, it is extremely difficult to differentiate between the two models. Therefore, we investigated the role of ROS in hypoxia-dependent gene induction triggered by Ni2+ and Co2+, as well as by hypoxic conditions. Recently, we have shown that the Ni2+, Co2+, or hypoxia induced expression of Cap43 that was dependent on HIF-1 (18) . The high inducibility of Cap43 by hypoxia via a HIF-1-dependent pathway in many cell lines suggested that it might be a good marker of the activation of signals that lead to HIF-1 activation and enhanced expression of hypoxia-related genes.

Exposure of A549 cells to Ni2+ or Co2+ resulted in increased ROS production in cells, as detected by the DCF method. We have previously shown that exposure of mouse 3T3 cells to NiCl2 caused increases of DCF fluorescence and that Ni2+ was a better inducer of ROS than H2O2 (15) . We also compared ROS production induced by Ni2+ or Co2+ in the same cell type. It was known that both Co2+ and Ni2+ produced oxidative stress in cells, perhaps by depletion of reduced glutathione (15 , 21) ; however, a comparison of the intensity of oxidative stress by both metals in the same cell type had not been previously examined. We have found that Co2+ was more active in generating ROS than Ni2+, but there was no correlation between the level of ROS in A549 cells and the degree of Cap43 gene induction.

The free radical scavenger 2-mercaptoethanol efficiently attenuated ROS production by Ni2+ or Co2+ but failed to suppress the enhanced Cap43 gene expression attributed to metals or hypoxia. We did not, however, show the level of ROS in A549 cells exposed to hypoxia, but it was conceivable that hypoxia might elevate ROS in these cells similarly to what has been found in the Hep3B cells (11) . In our experiments, we found that hypoxia increased the level of ROS (data not shown), however, this may be due to reoxygenation when the microplate was rapidly transferred from a hypoxic chamber to the microplate reader for measurement of DCF fluorescence. Failure to suppress the Cap43 gene expression by 2-mercaptoethanol was in agreement with the lack of activity of 2-mercaptoethanol on the expression of HIF-1-dependent plasmid alone or in combination with Ni2+, Co2+, DFX, or hypoxia.

Vitamin E seemed to be inefficient in suppressing ROS formation by both metals. ROS are considered to be important in Ni toxicity and mutagenicity, therefore, the observation that vitamin E did not suppress ROS produced by NiCl2 was in line with our previous findings that vitamin E did not inhibit chromosomal aberrations or mutagenesis in cells exposed to soluble nickel chloride (22 , 23) . However, vitamin E was somewhat effective at inhibiting the effects of carcinogenic water insoluble nickel sulfide particles (23) .

The role of ROS in the activation of HIF-1 is not clear (for review see Refs. 1 and 7 ). It was suggested that changes in cellular redox state signaled an activation of HIF-1 (24 , 25) . The fact that transition metals induced hypoxia-related genes and produced ROS in cells is not teleologically consistent with the observed induction of hypoxic genes by the free radical scavenger DFX (26) . Our results suggested that the role of ROS related to HIF-1 activation may have been overstated. From the experiments shown here, we conclude that ROS were, indeed, generated in cells exposed to metals that induce hypoxic genes, but it was unlikely that they participated in the hypoxic signal transduction pathways. A similar observation was made by Hohler et al. (27) , who found that ROS production was increased in PC12 cells during hypoxia but was not the cause of the hypoxia-driven tyrosine hydroxylase mRNA formation.

In summary, we concluded that ROS production was increased during exposure of A549 cells to Ni or Co, however, ROS were not involved in HIF-1 activation and did not cause up-regulation of Cap43. It is possible that these metals substituted for Fe in the oxygen sensor and thereby activated HIF and subsequently Cap43.


   FOOTNOTES
 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1 Supported by NIH Grants ES05512, ES00260, and CA16037. Back

2 To whom requests for reprints should be addressed, at New York University School of Medicine, Nelson Institute of Environmental Medicine, 57 Old Forge Road, Tuxedo, NY 10987. Phone: (914) 731-3516; Fax: (914) 351-2118; E-mail: salnikow{at}env.med.nyu.edu Back

3 The abbreviations used are: HIF, hypoxia-inducible factor; Co2+, cobalt; Ni2+, nickel; DFX, desferrioxamine; ROS, reactive oxygen species; H2O2, hydrogen peroxide; DCFH-DA, 2',7'-dichlorofluorescein diacetate; DCF, dichlorofluorescein. Back

Received 1/26/00. Accepted 5/11/00.


   REFERENCES
Top
 ABSTRACT
 Introduction
 Materials and Methods
 Results
 Discussion
 REFERENCES
 

  1. Semenza G. L. Hypoxia-inducible factor 1: master regulator of O2 homeostasis. Curr. Opin. Genet. Dev., 8: 588-594, 1998.[Medline]
  2. Shih S. C., Claffey K. P. Hypoxia-mediated regulation of gene expression in mammalian cells. Int. J. Exp. Pathol., 79: 347-357, 1998.[Medline]
  3. Huang L. E., Gu J., Schau M., Bunn H. F. Regulation of hypoxia-inducible factor 1 {alpha} is mediated by an O2-dependent degradation in domain via the ubiquitin-proteasome pathway. Proc. Natl. Acad. Sci. USA, 95: 7987-7992, 1998.[Abstract/Free Full Text]
  4. Namiki A., Brogi E., Kearney M., Kim E. A., Wu T., Coffinhal T., Varticovski L., Isner J. M. Hypoxia induces vascular endothelial growth factor in cultured human endothelial cells. J. Biol. Chem., 270: 31189-31195, 1995.[Abstract/Free Full Text]
  5. Graven K. K., McDonald R. J., Farber H. W. Hypoxia regulation of endothelial glyceraldehyde-3-phosphate dehydrogenase. Am. J. Physiol., 43: 347-355, 1998.
  6. Salnikow K., An W. G., Melillo G., Blagosklonny M. V., Costa M. Nickel-induced transformation shifts the balance between HIF-1 and p53 transcription factors. Carcinogenesis (Lond.), 20: 1819-1823, 1999.[Abstract/Free Full Text]
  7. Semenza G. L. Perspectives on oxygen sensing. Cell, 98: 281-284, 1999.[Medline]
  8. Goldberg M. A., Dunning S. P., Bunn H. F. Regulation of the erythropoietin gene: evidence that the oxygen sensor is a heme protein. Science (Washington DC), 242: 1412-1415, 1988.[Abstract/Free Full Text]
  9. Zhu H., Bunn H. F. Oxygen sensing and signaling: impact on the regulation of physiologically important genes. Respir. Physiol., 115: 239-247, 1999.[Medline]
  10. Fandrey J., Frede S., Jelkmann W. Role of hydrogen peroxide in hypoxia-induced erythropoietin production. Biochem. J., 303: 507-510, 1994.
  11. Chandel N. S., Maltepe E., Goldwasser E., Mathieu C. E., Simon M. C., Schumacker P. T. Mitochondrial reactive oxygen species trigger hypoxia-induced transcription. Proc. Natl. Acad. Sci. USA, 95: 11715-11720, 1998.[Abstract/Free Full Text]
  12. Vanden Hoek T. L., Becker L. B., Shao Z., Li C., Schumacker P. T. Reactive oxygen species released from mitochondria during brief hypoxia induced preconditioning in cardiomyocytes. J. Biol. Chem., 273: 18092-18098, 1998.[Abstract/Free Full Text]
  13. Kasprzak K. The role of oxidative damage in metal carcinogen city. Chem. Res. Toxicol., 4: 604-615, 1991.[Medline]
  14. Wang X., Yokoi I., Liu J., Mori A. Cobalt(II) and nickel(II) ions as promoters of free radicals in vivo: detected directly using electron spin resonance spectrometry in circulating blood in rats. Arch. Biochem. Biophys., 306: 402-406, 1993.[Medline]
  15. Salnikow K., Gao M., Voitkun V., Huang X., Costa M. Altered oxidative stress responses in nickel-resistant mammalian cells. Cancer Res., 54: 6407-6412, 1994.[Abstract/Free Full Text]
  16. Leonard S., Gannett P. M., Rojanasakul Y., Schwegler-Berry D., Castranova V., Vallyathan V., Shi X. Cobalt-mediated generation of reactive oxygen species and its possible mechanism. J. Inorg. Biochem., 70: 239-244, 1998.[Medline]
  17. Zhou D., Salnikow K., Costa M. Cap43, a novel gene specifically induced by Ni2+ compounds. Cancer Res., 58: 2182-2189, 1998.[Abstract/Free Full Text]
  18. Salnikow K., Blagosklonny M., Ryan H., Johnson R., Costa M. Carcinogenic nickel induces genes involved with hypoxic stress. Cancer Res., 60: 38-41, 2000.[Abstract/Free Full Text]
  19. LeBel C. P., Ischiropoulos H., Bondy S. C. Evaluation of the probe 2',7'-dichlorofluorescein as an indicator of reactive oxygen species formation and oxidative stress. Chem. Res. Toxicol., 5: 227-231, 1992.[Medline]
  20. Shi X., Dalal N. S., Kasprzak K. S. Generation of free radicals in reactions of Ni(II)-thiol complexes with molecular oxygen and model lipid hydroperoxides. J. Inorg. Biochem., 50: 211-225, 1993.[Medline]
  21. Lewis C. P., Demedts M., Nemery B. Indices of oxidative stress in hamster lung following exposure to cobalt(II) ions: in vivo and in vitro studies. Am. J. Respir. Cell Mol. Biol., 5: 163-169, 1991.
  22. Lin X. H., Sugiyama M., Costa M. Differences in the effect of vitamin E on nickel sulfide or nickel chloride induced chromosomal aberrations in mammalian cells. Mutat. Res., 260: 159-164, 1991.[Medline]
  23. Kargacin B., Klein C. B., Costa M. Mutagenic responses of nickel oxides and nickel sulfides in Chinese hamster V79 cell lines as the xanthine-guanine phosphoribosyl transferase locus. Mutat. Res., 300: 63-72, 1993.[Medline]
  24. Huang L. E., Arany Z., Livingston D. M., Bunn H. F. Activation of hypoxia-inducible transcription factor depends primarily upon redox-sensitive stabilization of its {alpha} subunit. J. Biol. Chem., 271: 32253-32259, 1996.[Abstract/Free Full Text]
  25. Wang G. L., Jiang B. H., Rue E. A., Semenza G. L. Hypoxia-inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular O2 tension. Proc. Natl. Acad. Sci. USA, 92: 5510-5514, 1995.[Abstract/Free Full Text]
  26. Halliwell B. Protection against tissue damage in vivo by desferrioxamine: what is its mechanism of action?. Free Radic. Biol. Med., 7: 645-651, 1989.[Medline]
  27. Hohler B., Lange B., Holzapfel B., Goldenberg A., Hanze J., Sell A., Testan H., Moller W., Kummer W. Hypoxic up-regulation of tyrosine hydroxylase gene expression is paralleled, but not induced, by increased generation of reactive oxygen species in PC12 cells. FEBS Lett., 115: 239-247, 1999.



This article has been cited by other articles:


Home page
 CarcinogenesisHome page
T. P. Ellen, Q. Ke, P. Zhang, and M. Costa
NDRG1, a growth and cancer related gene: regulation of gene expression and function in normal and disease states
Carcinogenesis, January 1, 2008; 29(1): 2 - 8.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Cell. ProteomicsHome page
L. C. Tu, X. Yan, L. Hood, and B. Lin
Proteomics Analysis of the Interactome of N-myc Downstream Regulated Gene 1 and Its Interactions with the Androgen Response Program in Prostate Cancer Cells
Mol. Cell. Proteomics, April 1, 2007; 6(4): 575 - 588.
[Abstract] [Full Text] [PDF]

Home page
 JCOHome page
J. Subramanian and R. Govindan
Lung Cancer in Never Smokers: A Review
J. Clin. Oncol., February 10, 2007; 25(5): 561 - 570.
[Abstract] [Full Text] [PDF]

Home page
 Cancer Res.Home page
C. E. Griguer, C. R. Oliva, E. E. Kelley, G. I. Giles, J. R. Lancaster Jr., and G. Y. Gillespie
Xanthine Oxidase-Dependent Regulation of Hypoxia-Inducible Factor in Cancer Cells
Cancer Res., February 15, 2006; 66(4): 2257 - 2263.
[Abstract] [Full Text] [PDF]

Home page
 Sci SignalHome page
R. H. Wenger, D. P. Stiehl, and G. Camenisch
Integration of Oxygen Signaling at the Consensus HRE
Sci. Signal., October 18, 2005; 2005(306): re12 - re12.
[Abstract] [Full Text] [PDF]

Home page
 Nucleic Acids ResHome page
U. Wimmer, Y. Wang, O. Georgiev, and W. Schaffner
Two major branches of anti-cadmium defense in the mouse: MTF-1/metallothioneins and glutathione
Nucleic Acids Res., October 12, 2005; 33(18): 5715 - 5727.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
N. A. Whitlock, N. Agarwal, J.-X. Ma, and C. E. Crosson
Hsp27 Upregulation by HIF-1 Signaling Offers Protection against Retinal Ischemia in Rats
Invest. Ophthalmol. Vis. Sci., March 1, 2005; 46(3): 1092 - 1098.
[Abstract] [Full Text] [PDF]

Home page
 Toxicol SciHome page
A. Vengellur and J. J. LaPres
The Role of Hypoxia Inducible Factor 1{alpha} in Cobalt Chloride Induced Cell Death in Mouse Embryonic Fibroblasts
Toxicol. Sci., December 1, 2004; 82(2): 638 - 646.
[Abstract] [Full Text] [PDF]

Home page
 BloodHome page
N. T.V. Le and D. R. Richardson
Iron chelators with high antiproliferative activity up-regulate the expression of a growth inhibitory and metastasis suppressor gene: a link between iron metabolism and proliferation
Blood, November 1, 2004; 104(9): 2967 - 2975.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Respir. Cell Mol. Bio.Home page
J. A. Whitsett, C. J. Bachurski, K. C. Barnes, P. A. Bunn Jr., L. M. Case, D. N. Cook, D. Crooks, M. W. Duncan, L. Dwyer-Nield, R. C. Elston, et al.
Functional Genomics of Lung Disease
Am. J. Respir. Cell Mol. Biol., August 1, 2004; 31(2/S1): S1 - S81.
[Full Text] [PDF]

Home page
 Mol. Pharmacol.Home page
T. Davidson, K. Salnikow, and M. Costa
Hypoxia Inducible Factor-1{alpha}-Independent Suppression of Aryl Hydrocarbon Receptor-Regulated Genes by Nickel
Mol. Pharmacol., December 1, 2003; 64(6): 1485 - 1493.
[Abstract] [Full Text] [PDF]

Home page
 Toxicol SciHome page
J. Kang, Y. Zhang, J. Chen, H. Chen, C. Lin, Q. Wang, and Y. Ou
Nickel-Induced Histone Hypoacetylation: The Role of Reactive Oxygen Species
Toxicol. Sci., August 1, 2003; 74(2): 279 - 286.
[Abstract] [Full Text] [PDF]

Home page
 Cancer Res.Home page
K. Salnikow, T. Davidson, Q. Zhang, L. C. Chen, W. Su, and M. Costa
The Involvement of Hypoxia-inducible Transcription Factor-1-dependent Pathway in Nickel Carcinogenesis
Cancer Res., July 1, 2003; 63(13): 3524 - 3530.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
N. Gao, B.-H. Jiang, S. S. Leonard, L. Corum, Z. Zhang, J. R. Roberts, J. Antonini, J. Z. Zheng, D. C. Flynn, V. Castranova, et al.
p38 Signaling-mediated Hypoxia-inducible Factor 1alpha and Vascular Endothelial Growth Factor Induction by Cr(VI) in DU145 Human Prostate Carcinoma Cells
J. Biol. Chem., November 15, 2002; 277(47): 45041 - 45048.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Lung Cell. Mol. Physiol.Home page
J. Araya, M. Maruyama, A. Inoue, T. Fujita, J. Kawahara, K. Sassa, R. Hayashi, Y. Kawagishi, N. Yamashita, E. Sugiyama, et al.
Inhibition of proteasome activity is involved in cobalt-induced apoptosis of human alveolar macrophages
Am J Physiol Lung Cell Mol Physiol, October 1, 2002; 283(4): L849 - L858.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
M. C. A. Duyndam, T. M. Hulscher, D. Fontijn, H. M. Pinedo, and E. Boven
Induction of Vascular Endothelial Growth Factor Expression and Hypoxia-inducible Factor 1alpha Protein by the Oxidative Stressor Arsenite
J. Biol. Chem., December 14, 2001; 276(51): 48066 - 48076.
[Abstract] [Full Text] [PDF]

Home page
 Cancer Res.Home page
C. Huang, J. Li, M. Costa, Z. Zhang, S. S. Leonard, V. Castranova, V. Vallyathan, G. Ju, and X. Shi
Hydrogen Peroxide Mediates Activation of Nuclear Factor of Activated T Cells (NFAT) by Nickel Subsulfide
Cancer Res., November 1, 2001; 61(22): 8051 - 8057.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Lung Cell. Mol. Physiol.Home page
A. S. Andrew, L. R. Klei, and A. Barchowsky
Nickel requires hypoxia-inducible factor-1{alpha}, not redox signaling, to induce plasminogen activator inhibitor-1
Am J Physiol Lung Cell Mol Physiol, September 1, 2001; 281(3): L607 - L615.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Salnikow, K.
Right arrow Articles by Costa, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Salnikow, K.
Right arrow Articles by Costa, M.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Cancer Research Clinical Cancer Research
Cancer Epidemiology Biomarkers & Prevention Molecular Cancer Therapeutics
Molecular Cancer Research Cancer Prevention Research
Cancer Prevention Journals Portal Cancer Reviews Online
Annual Meeting Education Book Meeting Abstracts Online