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Nickel Compound-Induced DNA Single-Strand Breaks in Chromosomal and Nuclear Chromatin in Human Blood Lymphocytes in Vitro: Role of Oxidative Stress and Intracellular Calcium
Abstract
The effects of nickel sulfate, and soluble forms of nickel carbonate hydroxide (NiCH), nickel subsulfide, and nickel oxide on delayed induction of DNA single-strand breaks (DNA SSBs) in chromosomal and nuclear chromatin of human blood lymphocytes in culture were studied. After 46 h of initial culture in supplemented RPMI-1640 media at 37 degrees C, human whole blood lymphocytes in culture were exposed to low concentrations (0-15 microM) of different nickel (Ni) compounds for 2 h, whereas only RPMI-1640 medium served as control. Immediately after 2 h of such exposure, both control and Ni-treated cells were washed with the same medium and incubated further in fresh complete RPMI-1640 culture medium for another 24h. After a total 70 h of incubation, cells were then arrested at metaphase. Two hours later, the induction of DNA SSBs involving both metaphase chromosomal and interphase nuclear chromatin was measured using the method of electron microscopy in situ end-labeling. The metaphase chromosomal chromatin showed significantly higher DNA SSBs (as measured by an increase in immunogold particles per microm2 chromatin) due to 15 microM NiCH and NiO when compared to the corresponding control value. Both NiCH and nickel oxide produced significantly higher induction of DNA SSBs than those of nickel subsulfide and nickel sulfate in chromosomal chromatin. The DNA SSBs in chromosomal chromatin were found to be significantly higher than those in nuclear chromatin due to different Ni compounds. Overall, the genotoxic potency seems to be decreased as follows: NiCH>nickel oxide>or=nickel subsulfide>nickel sulfate. Pretreatment of human blood lymphocytes with either catalase (a H2O2 scavenger), or superoxide dismutase (a scavenger of O2- radical) or dimethylthiourea (a hydroxyl radical scavenger), or N-acetylcysteine (GSH precursor) significantly reduced DNA SSBs in both chromosomal and nuclear chromatin induced by NiCH, suggesting the involvement of different types of oxidative stress in such genotoxicity. Deferoxamine (a highly specific iron chelator) pretreatment prevented NiCH-induced DNA SSBs in both chromosomal and nuclear chromatin suggesting a role of iron-mediated oxidative stress generating hydroxyl radical in such genotoxicity. Simultaneous treatment with either verapamil (an inhibitor of Ca 2+ through plasma membranes), or dantrolene (an inhibitor of mobilization of [Ca2+]i from endoplasmic reticulum), or BAPTA (a Ca2+ chelator) significantly reduced Ni compound-induced DNA SSBs in both chromosomal and nuclear chromatin, suggesting that Ni compound-induced destabilization of calcium homeostasis may also involved in the induction of such DNA SSBs.
... A number of experimental and epidemiological studies on the genotoxic effects of heavy metals and their compounds have been published. These demonstrate that arsenic 9, 10 , cadmium 11,12 , mercury 13,14 , lead 15 , chromium 16,17 , nickel 18,19 , manganese 20,21 and iron 22,23 are clastogens inducing chromosomal aberrations, micronuclei induction, sister chromatid exchange (SCE) and chromosomal loss in human and animal cells. ...
... Metal-induced oxidative stress has been shown to cause DNA damage through the production of reactive oxygen species (ROS) such as superoxide anion radical ( • O 2 -), hydrogen peroxide (H 2 O 2 ) and hydroxyl radical (OH • ) 24 . There is considerable evidence that ROS-mediated oxidative damage induced by several metals is an underlying basis of their genotoxicity 10,13,18,19,24 . Another important mechanism of metal-induced genotoxicity has been attributed to their ability to react with the sulfhydryl (-SH) groups 24,25 . ...
... This is also evident by the significant reduction in PCE/erythrocytes ratio in bone marrow cells. The mixture components such as arsenic 9, 10 , cadmium 11,12 , mercury 13,14 , lead 15 , chromium 16,17 , nickel 18,19 , manganese 20, 21 and iron 22,23 have been reported to produce cytogenetic damage, including chromosomal aberrations, micronuclei induction and SCE in bone marrow and other cells. The SCE assay is recognized as a good index of DNA damage and can be detected at lower doses of the compounds than those required to induce chromosomal aberrations 42 . ...
The current study examines the genotoxic effects of subchronic exposure via drinking water to a mixture of eight metals (arsenic, cadmium, lead, mercury, chromium, nickel, manganese and iron) found as contaminants of water sources in different parts of India and its possible association with oxidative stress. Male rats were exposed to the mixture at 0, 1, 10 and 100 times the mode concentration of each metal daily for 90 days. Another dose group at concentration equivalent to maximum permissible limit (MPL) for each metal and a reference group given ip cyclophosphamide were incorporated. The mixture at 100x level significantly increased chromosomal aberrations and micronuclei induction (2.4 folds) in bone marrow cells and reduced the ratio of polychromatic to normochromatic erythrocytes by 25%. The mixture significantly increased sister chromatid exchange in bone marrow (1.67 and 2.3 folds) and spleen (1.57 and 1.98 folds) cells with both 10x and 100x doses. Cyclophosphamide was more potent than the mixture in causing cytogenetic damage in these parameters. In rat spleen, the mixture at 10x and 100x doses caused dose-dependent increase in lipid peroxidation (25.95 and 52.71%) and decrease in the activities of superoxide dismutase (20.36 and 40.62%), catalase (18.24 and 35.50%), glutathione peroxidase (22.33 and 36.12%) and glutathione reductase (19.22 and 31.35%) and in the level of GSH (19.76 and 35.15%). The results suggest that the mixture induced genotoxicity in rat bone marrow and spleen cells at concentrations relatively higher than that found in groundwater sources and the genotoxic effect could relate to induction of oxidative stress. However, observations with lower doses indicate that additive or synergistic interactions following exposure to metal components at MPL levels or at mode concentrations of contemporary groundwater levels in India may not result in clastogenicity in male rats.
... Nickel has more than one binding site in cells and can bind with DNA replication proteins, which may significantly alter DNA synthesis events (Christie and Tummolo 1989). Nevertheless, nickel displayed toxic effects at high concentrations and could induce DNA damage and/or inhibition of DNA replication and repair (Gullì et al. 2018, Kumar et al. 2017, M'Bemba-Meka et al. 2005, Woniak and Basiak 2002. Nickel can damage DNA directly or indirectly. ...
... Nickel can damage DNA directly or indirectly. It might damage DNA via ROS stimulation, directly bind to DNA, and cause DNA single-strand breaks (Guo et al. 2019, Woniak and Basiak 2002, Kumar et al. 2017, M'Bemba-Meka et al. 2005. These data indicated that the DNA and its metabolism process might be a target of nickel, and the excess might disturb the metabolism of DNA in the P. tricornutum. ...
Nickel acts as an essential trace nutrient or toxicant for organisms, depending on its concentration. The increased concentrations of nickel, due to anthropogenic activity, in the aquatic environment are potential threats to aquatic organisms. However, the knowledge on toxic mechanisms of nickel to microalgae remains incompletely understood. In the present study, we investigated the toxic effects of nickel in the cosmopolitan diatom Phaeodactylum tricornutum via evaluation of physiological and transcriptome responses. The results showed that the median effective concentration-72 h (EC50-72 h) and EC50-96 h of nickel was 2.48 ± 0.33 and 1.85 ± 0.17 mg/L, respectively. The P. tricornutum cell abundance and photosynthesis significantly decreased by 1 mg/L of nickel. Results from photosynthetic parameters including efficiency of the oxygen evolving complex (OEC) of photosystem II (PSII) (Fv/F0), maximum photosynthetic efficiency of PS II (Fv/Fm), electron transport rate (ETR), actual photosynthetic efficiency of PS II (Y(II)), non-photochemical quenching (NPQ), and photochemical quenching (qP) indicated that OEC of PS II might be impaired by nickel. The transcriptome data also reveal that OEC apparatus coding gene PS II oxygen-evolving enhancer protein 2 (PsbP) was regulated by nickel. Moreover, induced reactive oxygen species (ROS) production and chlorophyll a content were also detected under nickel stress. Transcriptome analysis revealed that nickel affected a variety of differentially expressed genes (DEGs) that involved in redox homeostasis, nitrogen metabolisms, fatty acids, and DNA metabolism. However, thiol-disulfide redox system might play important roles in nickel-induced oxidative stress resistance. This study improved the understanding of the toxic effect of nickel on the diatom P. tricornutum.
... Besides, Cr is also involved in the lipids metabolism and in the protein anabolism [1][2][3]. Ni takes part in the tissular regulation of phospholipids, triglycerides, urea, glucose, glycogen and ATP levels [4,5]. Cu, Mn and Se are critical elements of the three main cellular antioxidant enzymes, the copper-zinc-superoxide dismutase (Cu-Zn-SOD), the manganese-superoxide dismutase (Mn-SOD) and the glutathione-peroxidase (GSH-Px), respectively. ...
... The fact that the AEG had the higher concentrations, followed with the AE-ANEG and the ANEG in our study, verifies and reinforces the previous reports. Ni controls tissular levels of phospholipids, triglycerides, urea, glucose, glycogen and ATP [4,5]. Due to these roles is critical among sportsmen to maintain high organic concentrations of this mineral. ...
Background
The aim of the present study was to determine changes in serum concentrations of trace elements Cooper (Cu), Chromiun (Cr), Manganesum (Mn), Nickel (Ni) and Selenium (Se) in high-level sportsmen. Methods
Eighty professional athletes of different metabolic modalities, were recruited before the start of their training period. Thirty one sedentary participants of the same geographic area constituted the control group. Cu, Cr, Mn, Ni and Se analysis was performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). ResultsHigher concentrations of Cr (p < 0.001), Mn (p < 0.085), and Ni (p < 0.001) were found in sportsmen in comparison to controls, inversely, Se values were lower (p < 0.001) among sportsmen. When sportsmen were classified by metabolic modalities, it was found that aerobic-anaerobic group had higher (p < 0.01) Cu concentrations than controls and the other sportsmen. The highest Cr values were found in aerobic participants. For Mn, the major levels were found in aerobic and aerobic-anaerobic groups as well (p < 0.001). The lowest Se levels were found among anaerobic sportsmen (p < 0.001). Conclusion
This research showed that daily, continuum physical training induced alterations in serum essential minerals concentrations, as well as that these changes can be dependent of the exercise modality practiced.
... Nickel compounds are able to cause the cell transformation and chromatin damage ) Cai and Zhuang, 1999;M'Bemba-Meka et al., 2005) but they are not mutagenic in a wide range of bacterial mutagenesis assays and are only weakly mutagenic in cultured mammalian cells (Biggart and Costa, 1986;klein et al., 1991;Kerckaert et al., 1996). One possible explanation for this is nickel cause the DNA damage and cell transformation via generation of reactive oxygen species (ROS) (Salnikow and Costa, 2000). ...
... Nickel is a redox-active metal that can catalyse Fenton-type reactions (Huang et al., 1993;Chen et al., 2003). In cells treated with nickel compounds, increase in DNA stand breaks, DNA-protein crosslinks and sister chromatid exchange was observed and these are shown to result from the increase in reactive oxygen species (Chakrabarti et al., 2001;M'Bemba-Meka et al., 2005. Nickel (II) ions can catalyze the generation of OH radicals from H2O2. ...
Heavy metals constitute an important class of environmental contaminants that classified as human carcinogens according to the US Environmental Protection Agency and the International Agency for Research on Cancer. They affect human health through occupational and environmental exposure. Multiple experimental epidemiological studies indicate that heavy metals such as Nickel and Cadmium can induce several types of cancer significantly pulmonary cancers, but the mechanisms underlying the carcinogenesis are not well understood yet. This metals are genotoxic elements for human, while they are typically weak mutagens, indicating that indirect mechanisms may be primary responsible for their genotoxicity. Several studies suggest that epigenetic mechanisms may play an important role in metal-induced carcinogenesis. Here, we review studies that investigate the common mechanisms of nickel and cadmium-induced carcinogenesis, include DNA methylation, histone modification, induction of oxidative stress, interference with DNA repair system, and interruption of cell growth and proliferation through signaling pathway and dysregulation of tumor suppressor genes.
... Normal-scale Nickel (Ni) is used in many industrial and consumer products, including stainless steel, magnets, coinage, rechargeable batteries, electric guitar strings and special alloys since long times (Chen et al., 2003;Kasprzak et al., 2003;Meka et al., 2005). However, some significant studies have shown that these normal-scale Ni and Ni-compounds produce hazardous effects to the environment and human health (Kasprzak et al., 2003;Hao et al., 2006;Duman and Ozturk, 2010). ...
... Oxidative stress elicits a wide variety of physiological and cellular events including stress, inflammation, DNA damage and apoptosis (Asharani et al., 2009;Ahamed et al., 2010b). Experimental evidence has shown that bulk form of Ni has potential to induce oxidative stress and DNA damage in different cell lines (Chen et al., 2003;Cavallo et al., 2003;Meka et al., 2005Meka et al., , 2006. Oxidative stress occurs when generation of ROS exceed the capacity of antioxidant defense mechanism. ...
Nickel nanoparticle (Ni NP) is increasingly used in modern industries such as catalysts, sensors and electronic applications. Due to wide-spread industrial applications the inhalation is the primary source of exposure to Ni NPs. However, data demonstrating the effect of Ni NPs on the pulmonary system remain scarce. The present study was designed to examine the toxic effect of human lung epithelial A549 cells treated with well characterized Ni NPs at the concentrations of 0, 1, 2, 5, 10 and 25 μg/ml for 24 and 48 h. Mitochondrial function (MTT assay), membrane leakage of lactate dehydrogenase (LDH assay), reduced glutathione (GSH), reactive oxygen species (ROS), membrane lipid peroxidation (LPO) and caspase-3 activity were assessed as toxicity end points. Results showed that Ni NPs reduced mitochondrial function and induced the leakage of LDH in dose and time-dependent manner. Ni NPs were also found to induce oxidative stress in dose and time-dependent manner indicated by depletion of GSH and induction of ROS and LPO. Further, activity of caspase-3 enzyme, marker of apoptosis was significantly higher in treated cells with time and Ni NPs dosage. The results exhibited significant toxicity of Ni NPs in human lung epithelial A549 cells which is likely to be mediated through oxidative stress. This study warrants more careful assessment of Ni NPs before their industrial applications.
... 22,23 Many in vivo and in vitro studies have been conducted on the genotoxic effects of nickel. [24][25][26][27] To determine the genotoxicity, comet assay, Salmonella/microsome mutagenicity (AMES) test, sister chromatid exchange assay, chromosome abnormality test, and micronucleus test were performed. 28 According to the literature review, it is noted that bone marrow [29][30][31][32] and embryos 5 were used to determine genotoxicity. ...
... The decrease in dry weight and cell division may result of the inhibition of protein synthesis [31]. Cytoskeleton and cell protein could be a cell target for nickel sulfate [30,32,33]. Change of the protein structure cause a decrease in enzyme activity which lead to inhibition of cell growth or induction of mutation. ...
... Nickel chloride treatment results in a significant elevation in the frequency of SCEs/cell which is in agreement with the other reports in human lymphocytes 9,14,15 . It was reported that the oxidative stress induced by nickel compounds leads to a variety of genetic defects on chromatin 4 . ...
Andrographolide, the main constituent of Andrographis paniculata is widely used as herbal remedy due to its anti-inflammatory, antioxidant and anti-cancer activities. In this study, antigenotoxic potential of andrographolide (AG) has been assessed by analyzing the DNA damage in the form of sister chromatid exchange (SCE) in cultured peripheral blood lymphocytes (PBLs). Cells treated with nickel chloride (1 mM) in combination with different concentration andrographolide (4-20 µg/ml) showed significant (p<0.05) reduction in the formation of sister chromatid exchanges. The data suggests that andrographolide has strong antigenotoxic potential to inhibit sister chromatid exchanges induced by nickel.
... We assessed recently primary genotoxicity of nickel (Ni) and nickel oxide (NiO) NPs by using a range of assays including comet assay, micronucleus assay, analysis of chromosome aberration and a set of reporter cells (Akerlund et al. 2017;Di Bucchianico et al. 2018). In these studies, we showed an ability of these NPs to cause DNA damage in lung cells, results in line with other studies (Latvala et al. 2016;M'Bemba-Meka, Lemieux, and Chakrabarti 2005). Furthermore, inflammatory effects of NiO NPs have been shown both in vitro (Capasso, Camatini, and Gualtieri 2014) and in vivo (Nishi et al. 2009;Gillespie et al. 2010;Morimoto et al. 2010;Cao et al. 2016;Bai et al. 2017). ...
Nanoparticle-induced genotoxicity can arise through different mechanisms, and generally, primary and secondary genotoxicity can be distinguished where the secondary is driven by an inflammatory response. It is, however, yet unclear how a secondary genotoxicity can be detected using in vitro methods. The aim of this study was to investigate inflammation and genotoxicity caused by agglomerated nickel (Ni) and nickel oxide (NiO) nanoparticles and, furthermore, to explore the possibility to test secondary (inflammation-driven) genotoxicity in vitro. As a benchmark particle to compare with, we used crystalline silica (quartz). A proteome profiler antibody array was used to screen for changes in release of 105 different cytokines and the results showed an increased secretion of various cytokines including vascular endothelial growth factor (VEGF) following exposure of macrophages (differentiated THP-1 cells). Both Ni and NiO caused DNA damage (comet assay) following exposure of human bronchial epithelial cells (HBEC) and interestingly conditioned media (CM) from exposed macrophages also resulted in DNA damage (2- and 3-fold increase for Ni and NiO, respectively). Similar results were also found when using a co-culture system of macrophages and epithelial cells. In conclusion, this study shows that it is possible to detect a secondary genotoxicity in lung epithelial cells by using in vitro methods based on conditioned media or co-cultures. Further investigation is needed in order to find out what factors that are causing this secondary genotoxicity and whether such effects are caused by numerous nanoparticles.
... Like Cr(VI), Ni compounds are classified as carcinogenic to humans according to the IARC, with support from many worker and experimental animal studies [38,[42][43][44][45]. In 2012, the IARC concluded that high cytotoxic concentrations as well as the presence of inflammation may be needed to induce carcinogenicity [38,[46][47][48][49]. Solubility properties and speciation may play a role in carcinogenic potency of different Ni compounds with the release and accumulation of ionic Ni of seemingly high importance [38,42,50]. ...
In 2017, the International Agency for Research on Cancer classified welding fumes as “carcinogenic to humans” (Group 1). Both mild steel (MS) welding, where fumes lack carcinogenic chromium and nickel, and stainless steel (SS) increase lung cancer risk in welders; therefore, further research to better understand the toxicity of the individual metals is needed. The objectives were to (1) compare the pulmonary toxicity of chromium (as Cr(III) oxide [Cr2O3] and Cr (VI) calcium chromate [CaCrO4]), nickel [II] oxide (NiO), iron [III] oxide (Fe2O3), and gas metal arc welding-SS (GMAW-SS) fume; and (2) determine if these metal oxides can promote lung tumors. Lung tumor susceptible A/J mice (male, 4–5 weeks old) were exposed by oropharyngeal aspiration to vehicle, GMAW-SS fume (1.7 mg), or a low or high dose of surrogate metal oxides based on the respective weight percent of each metal in the fume: Cr2O3 + CaCrO4 (366 + 5 μg and 731 + 11 μg), NiO (141 and 281 μg), or Fe2O3 (1 and 2 mg). Bronchoalveolar lavage, histopathology, and lung/liver qPCR were done at 1, 7, 28, and 84 days post-aspiration. In a two-stage lung carcinogenesis model, mice were initiated with 3-methylcholanthrene (10 μg/g; intraperitoneal; 1x) or corn oil then exposed to metal oxides or vehicle (1 x/week for 5 weeks) by oropharyngeal aspiration. Lung tumors were counted at 30 weeks post-initiation. Results indicate the inflammatory potential of the metal oxides was Fe2O3 > Cr2O3 + CaCrO4 > NiO. Overall, the pneumotoxic effects were negligible for NiO, acute but not persistent for Cr2O3 + CaCrO4, and persistent for the Fe2O3 exposures. Fe2O3, but not Cr2O3 + CaCrO4 or NiO significantly promoted lung tumors. These results provide experimental evidence that Fe2O3 is an important mediator of welding fume toxicity and support epidemiological findings and the IARC classification.
... Deferoxamine has previously been suggested to prevent DNA-protein crosslink formation induced by poorly soluble Ni 3 S 2 [45]. Furthermore, in studies on lymphocytes exposed to Ni 5 (CO 3 ) 2 (OH) 6 ·4H 2 O, M'Bemba-Meka and co-workers showed a protective effect of both deferoxamine and calcium modulators for the formation of DNA strand breaks and sister-chromatid exchange [46,47]. In our study, we also found protection from NiO-induced apoptosis and necrosis from all inhibitors/chelators in line with the fact that cellular Ca 2+ overload, or perturbation of intracellular Ca 2+ compartmentalization, can cause cytotoxicity and trigger either apoptotic or necrotic cell death [48]. ...
Background:
Genotoxicity is an important toxicological endpoint due to the link to diseases such as cancer. Therefore, an increased understanding regarding genotoxicity and underlying mechanisms is needed for assessing the risk with exposure to nanoparticles (NPs). The aim of this study was to perform an in-depth investigation regarding the genotoxicity of well-characterized Ni and NiO NPs in human bronchial epithelial BEAS-2B cells and to discern possible mechanisms. Comparisons were made with NiCl2 in order to elucidate effects of ionic Ni.
Methods:
BEAS-2B cells were exposed to Ni and NiO NPs, as well as NiCl2, and uptake and cellular dose were investigated by transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS). The NPs were characterized in terms of surface composition (X-ray photoelectron spectroscopy), agglomeration (photon cross correlation spectroscopy) and nickel release in cell medium (ICP-MS). Cell death (necrosis/apoptosis) was investigated by Annexin V-FITC/PI staining and genotoxicity by cytokinesis-block micronucleus (cytome) assay (OECD 487), chromosomal aberration (OECD 473) and comet assay. The involvement of intracellular reactive oxygen species (ROS) and calcium was explored using the fluorescent probes, DCFH-DA and Fluo-4.
Results:
NPs were efficiently taken up by the BEAS-2B cells. In contrast, no or minor uptake was observed for ionic Ni from NiCl2. Despite differences in uptake, all exposures (NiO, Ni NPs and NiCl2) caused chromosomal damage. Furthermore, NiO NPs were most potent in causing DNA strand breaks and generating intracellular ROS. An increase in intracellular calcium was observed and modulation of intracellular calcium by using inhibitors and chelators clearly prevented the chromosomal damage. Chelation of iron also protected against induced damage, particularly for NiO and NiCl2.
Conclusions:
This study has revealed chromosomal damage by Ni and NiO NPs as well as Ni ionic species and provides novel evidence for a calcium-dependent mechanism of cyto- and genotoxicity.
... Despite the classification of nickel compounds as carcinogenic, the underlying mechanisms that may result in lung cancer are still poorly understood. Previous studies have suggested both direct DNA damage in the form of DNA strand breaks [M'Bemba-Meka et al., 2005;Latvala et al., 2016] and indirect genotoxic effects due to inhibition of DNA repair [Schwerdtle et al., 2002;IARC, 2012]. Oxidative stress has been suggested to be an important underlying mechanism and increased levels of 8-oxo-2-deoxyguanosine have, for example, been observed in the lung of mice exposed to different nickel compounds [Kawanishi et al., 2001]. ...
Nickel (Ni) compounds are classified as carcinogenic to humans but the underlying mechanisms are still poorly understood. Furthermore, effects related to nanoparticles (NPs) of Ni have not been fully elucidated. The aim of this study was to investigate genotoxicity and muta-genicity of Ni and NiO NPs and compare the effect to soluble Ni from NiCl 2. We employed different models; i.e., exposure of (1) human bronchial epithelial cells (HBEC) followed by DNA strand break analysis (comet assay and g-H2AX staining); (2) six different mouse embry-onic stem (mES) reporter cell lines (ToxTracker) that are constructed to exhibit fluorescence upon the induction of various pathways of relevance for (geno)toxicity and cancer; and (3) mES cells followed by mutagenicity testing (Hprt assay). The results showed increased DNA strand breaks (comet assay) for the NiO NPs and at higher doses also for the Ni NPs whereas no effects were observed for Ni ions/ complexes from NiCl 2. By employing the reporter cell lines, oxidative stress was observed as the main toxic mechanism and protein unfolding occurred at cytotoxic doses for all three Ni-containing materials. Oxidative stress was also detected in the HBEC cells following NP-exposure. None of these materials induced the reporter related to direct DNA damage and stalled replication forks. A small but statistically significant increase in Hprt mutations was observed for NiO but only at one dose. We conclude that Ni and NiO NPs show more pronounced (geno)toxic effects compared to Ni ions/complexes, indicating more serious health concerns. Environ. Mol. Mutagen. 00:000-000, 2017.
... The catalytic ability of U in the reaction between H 2 O 2 and DNA provides a mechanism for its genotoxicity and justifies further studies on this reaction. Uranium (Miller et al., 2002;Garmash et al., 2014) as well as plutonium (Claycamp and Luo, 1994) are active as redox catalysts in this reaction, as are also several other metals (Pratviel, 2012), including iron (Rajasinghe et al., 1990;Messina and Dawson, 2000;Rai et al., 2001;Kawanishi et al., 2002;Battin and Brumaghim, 2008;Liu and Hu, 2009;Berndt et al., 2010;Karbownik-Lewińska et al., 2012;Hart et al., 2013), copper (Aronovitch et al., 2007;Battin and Brumaghim, 2008;Barbosa et al., 2009;Hart et al., 2013), chromium Shi et al., 1999Shi et al., , 2000Qi et al., 2000;López-Burillo et al., 2003;Hart et al., 2013), cobalt (Mao et al., 1996;Ivancsits et al., 2002;Kawanishi et al., 2002), nickel (Hong et al., 1997;Lynn et al., 1997;Kawanishi et al., 2002;Cavallo et al., 2003;M'Bemba-Meka et al., 2005), vanadium (Sakurai, 1994;Shi et al., 1996aShi et al., , 1996bYe et al., 1999;Zhang et al., 2010) and lead (Yang et al., 1999). ...
Uranium (U) is a chemo-toxic, radiotoxic and even a carcinogenic element. Due to its radioactivity, the effects of U on humans health have been extensively investigated. Prolonged U exposure may cause kidney disease and cancer. The geological distribution of U radionuclides is still a great concern for human health. Uranium in groundwater, frequently used as drinking water, and general environmental pollution with U raise concerns about the potential public health problem in several areas of Asia. The particular paleo-geological hallmark of India and other Southern Asiatic regions enhances the risk of U pollution in rural and urban communities. This paper highlights different health and environmental aspects of U as well as uptake and intake. It discusses levels of U in soil and water and the related health issues. Also described are different issues of U pollution, such as U and fertilizers, occupational exposure in miners, use and hazards of U in weapons (depleted U), U and plutonium as catalysts in the reaction between DNA and H2O2, and recycling of U from groundwater to surface soils in irrigation. For use in medical geology and U research, large databases and data warehouses are currently available in Europe and the United States.
... Exposure to airborne particulate matter (PM) and halo-alkanebased pesticides was linked to damaged mitochondrial DNA (Budnik et al. 2013;Hou et al. 2010). Environmental contaminants, such as As, nickel (Ni), and ultrafine PM, were reported to produce increased DNA SSB in exposed individuals (Avogbe et al. 2005;Basu et al. 2005;Glei et al. 2005;M'Bemba-Meka, Lemieux, and Chakrabarti 2005;Popp et al. 1997). Levels of DNA SSB may be used to distinguish affected versus unaffected populations (Basu et al. 2005). ...
Environmental health science aims to link environmental pollution sources to adverse health outcomes to develop effective exposure intervention strategies that reduce long-term disease risks. Over the past few decades, the public health community recognized that health risk is driven by interaction between the human genome and external environment. Now that the human genetic code has been sequenced, establishing this “G × E” (gene–environment) interaction requires a similar effort to decode the human exposome, which is the accumulation of an individual’s environmental exposures and metabolic responses throughout the person’s lifetime. The exposome is composed of endogenous and exogenous chemicals, many of which are measurable as biomarkers in blood, breath, and urine. Exposure to pollutants is assessed by analyzing biofluids for the pollutant itself or its metabolic products. New methods are being developed to use a subset of biomarkers, termed bioindicators, to demonstrate biological changes indicative of future adverse health effects. Typically, environmental biomarkers are assessed using noninvasive (excreted) media, such as breath and urine. Blood is often avoided for biomonitoring due to practical reasons such as medical personnel, infectious waste, or clinical setting, despite the fact that blood represents the central compartment that interacts with every living cell and is the most relevant biofluid for certain applications and analyses. The aims of this study were to (1) review the current use of blood samples in environmental health research, (2) briefly contrast blood with other biological media, and (3) propose additional applications for blood analysis in human exposure research.
... The instability of this superoxide anion radical then results in its rapid disproportionation in water to hydrogen peroxide [29], which in turn can react via an iron-catalyzed Haber-Weiss reaction to form the hydroxyl radical [30]. Because of the nonspecific reactivity of the hydroxyl radical, it can damage a variety of biological systems via induction of lipid and protein peroxidation [31], degradation of deoxyribose [32] and promotion of DNA strand breaks [33] [34], leading to cell death. ...
Almost all cells are easily killed by exposure to potent oxidants. Indeed, major pathogen defense mechanisms in both animal and plant kingdoms involve production of an oxidative burst, where host defense cells show an invading pathogen with reactive oxygen species (ROS). Although cancer cells can be similarly killed by ROS, development of oxidant-producing chemotherapies has been limited by their inherent nonspecificity and potential toxicity to healthy cells. In this paper, we describe the targeting of an ROS-generating molecule selectively to tumor cells using folate as the tumor-targeting ligand. For this purpose, we exploit the ability of 9,10-phenanthraquinone (PHQ) to enhance the continuous generation of H2O2 in the presence of ascorbic acid to establish a constitutive source of ROS within the tumor mass. We report here that incubation of folate receptor-expressing KB cells in culture with folate-PHQ plus ascorbate results in the death of the cancer cells with an IC50 of ~10 nM (folate-PHQ). We also demonstrate that a cleavable spacer linking folate to PHQ is significantly inferior to a noncleavable spacer, in contrast to most other folate-targeted therapeutic agents. Unfortunately, no evidence for folate-PHQ mediated tumor regression in murine tumor models is obtained, suggesting that unanticipated impediments to generation of cytotoxic quantities of ROS in vivo are encountered. Possible mechanisms and potential solutions to these unanticipated results are offered.
... The cytotoxicity and genotoxicity of elemental Ni and Co, and their compounds, are well-established (Cangul et al. 2002;Denkhaus and Salnikow 2002;Costa et al. 2005;Muñoz and Costa 2012;Schaumlöffel 2012;Simonsen et al. 2012). Nickel, Fe and Co metals and their compounds act synergistically and directly to enhance mutagenicity and tumour formation by inhibiting the repair of DNA strand breakage via the production of reactive oxygen radicals (Beyersman 2002;De Boeck et al. 2003;M'Bemba-Meka et al. 2005;Patel et al. 2012). The ability of implanted ballistic tungsten alloys containing Ni, Co and Fe to generate tumours in animals has been researched widely because of the severe wounding of soldiers by tungsten alloy fragments (Centeno et al. 2014). ...
Failure to distinguish between elemental tungsten and tungsten alloys has caused confusion, especially about their relative toxicity in shotgun ammunition. Controlled experiments indicate that the carcinogenicity of embedded tungsten–nickel–cobalt alloys derives from their nickel and cobalt content, and not the tungsten. The carcinogenicity of metallic nickel and cobalt implants in animal tissues is well-established. Studies in which pure tungsten metal is embedded in animal and human tissues indicate that there is no toxicity or carcinogenicity developed locally or systemically. The exposed tungsten corrodes slowly in the tissue fluids and is excreted from the body. Chronic studies in which pure tungsten-based shot are placed, continuously, in the foregut of ducks over 150 days indicate that there are no adverse physiological effects, nor disruption of ducks’ reproduction and development of their progeny. This type of shot is environmentally safe and non-toxic to animals. Shot containing nickel could pose health problems to animals if embedded in their tissues. The use of known toxic metals in lead-free shot should be subjected to further examination and, if warranted, regulation.
... En el caso concreto de los metales (hierro, zinc y cromo), la investigación corroboró el efecto citotóxico in vitro referido en la literatura (Vargas, et al. 2001). Este fenómeno esta asociado a la elevada capacidad que poseen estos compuestos iónicos para inactivar proteínas involucradas en la replicación, transcripción y reparación del ADN, además de tener reconocida la habilidad para inducir la formación de especies reactivas de oxigeno, provocando finalmente daños oxidativos no reparables al ADN y apoptosis (Alexandrov, et al. 2005;M'Bemba, et al. 2005). ...
The objective of this study was to describe cytogenotoxic changes in human buccal epithelial cells and their association with selected occupational exposures to chemical products (antineoplastic agents, grain dust, carbon dioxide, ammonia, naphtha, and complex mix- tures of toluene, methanol, xylene, chlorethylene and welding fumes), taking into account age, job seniority and personal habits. A cross-sectional descriptive study, consisting of 31 controls and 88 exposed workers, was conducted. Information on age, seniority, type and du- ration of exposure, use of personal protective equipment and personal habits was obtained. Buccal mucosal cells were examined for frequency of genotoxic (micronu- clei) and cytotoxic (binucleation, pycnosis, condense chromatin and caryolysis) abnormalities. Associations between these abnormalities and age, seniority and personal habits were analyzed with Pearson correlation coefficients. Results indicated that 70.45% (n=62) of workers did not use respiratory protection and 82.95% (n=73) were occupationally exposed to chemicals. Antineoplastic agents were significantly associated with cytogenotoxic changes; no relationship was found with grain dust or naphtha. No associations were found between cytotoxicity and age (r=0.10), seniority (r=0.14), smoking (r=0.02) or alcohol use (r=0.11). We conclude that frequency of cytogenotoxic abnormalities was associated with exposure to antineoplastic drugs. Cytotoxicity is not correlated with age, job seniority or personal lifestyle habits.
... Patlolla et.al reported similar results using HepG2 cells after exposure to potassium dichromate for 48 h (Patlolla et al., 2009). Although the mutagenic potential of nickel compounds assessed in many mutational systems (from salmonella to mammalian cells) in vitro is low, single-strand DNA breakage induced by Ni compounds , including nickel chloride, has been reported in isolated human lymphocytes in vitro and in Chinese hamster ovary cells (Chen et al., 2003; M'Bemba-Meka et al., 2005). Using the Comet assay, our results indicate that NiCl 2 could only induce DNA damage in human B lymphoblastoid cells at the highest concentration, and longer exposure (48 h) to NiCl 2 did not significantly increase the levels of DNA damage in human B lymphoblastoid cells. ...
In the present study, human B lymphoblastoid cells were exposed to potassium dichromate and/or nickel chloride for 24h or 48h. The cell viability and DNA damage induced by these compounds was measured with the CCK-8 assay and Comet assay, respectively. In addition, the generation of reactive oxygen species (ROS) and the levels of malondialdehyde (MDA) were measured using commercially available kits. Our results indicated that potassium dichromate could decrease cell viability and induce DNA damage in human B lymphoblastoid cells in a time - and concentration - dependent manner, but the toxicity of nickel chloride was not so obvious at concentrations used in our study. The results of ROS showed that both two compounds could only induce weak elevation of ROS level, but MDA levels were significantly enhanced. Antagonistic effects of cytotoxicity were mainly found between Cr (VI) and Ni (II), and synergistic effects of DNA damage and oxidative stress were partially found between these two compounds. Moreover, there were good correlations between the results of comet assay and the results of oxidative stress assays. It is suggested that synergistic DNA damage induced by simultaneously exposure of hexavalent chromium and nickel compounds is possibly related to oxidative stress.
... Water collected at Mali Kukar Lake contained markedly elevated levels of nickel (Ni) and titanium (Ti), which have previously been confirmed as genotoxic. Using the alkaline Comet assay on human lymphocytes, Meka et al. (2005) showed that Ni compounds possess a significant capacity to induce single strand breaks in DNA and that Ni genotoxicity was potentiated by oxidative stress. Oxidative DNA damage caused by Ni has also been reported by other authors (Huang et al., 1995; Wozniak and Blasiak, 2002; Kawanishi et al., 2002; Cavallo et al., 2003). ...
As an important metal in industry, national defense, and production, nickel widely exists in nature and is also a necessary trace element for human beings and animals. Nickel deficiency will affect the growth and development of animals, the contents of related active substances, enzymes and other essential elements in vivo. However, excessive nickel or longer nickel exposure can induce excessive free radicals (reactive oxygen species and reactive nitrogen) in the body, which can lead to a variety of cell damage, apoptosis and canceration, and ultimately pose negative effects on the health of the body. Among them, the intestinal tract, as the largest interface between the body and the external environment, greatly increases the contact probability between nickel or nickel compounds and the intestinal mucosal barrier, thus, the intestinal structure and function are also more vulnerable to nickel damage, leading to a series of related diseases such as enteritis. Therefore, this paper briefly analyzed the damage mechanism of nickel or its compounds to the intestinal tract from the perspective of four intestinal mucosal barriers: mechanical barrier, immune barrier, microbial barrier and chemical barrier, we hope to make a certain theoretical contribution to the further research and the prevention and treatment of nickel related diseases.
DNA damage induced by Nickel chloride in lymphocytes has been studied in-vitro. The sister chromatids exchange and single-cell gel electrophoresis (SCGE), or comet assay were used to measure the level of DNA damage in terms of SCE frequency and comet parameters. Silymarin is a natural protective compound, isolated from Silybum marianum seeds and reported for its anti-genotoxic properties. In this study, the peripheral blood lymphocytes were administrated along with silymarin and Nickel chloride (NiCl 2) to evaluate the antigenotoxic effect of silymarin against NiCl 2 mediated genotoxicity. A significant (P<0.05) increase in the tail moment and SCE frequency indicating DNA damage was observed in NiCl 2 (129.59 µg/mL) treated samples. Simultaneously, a gradual decrease was observed in the tail moment, and SCE frequency in silymarin-treated samples against NiCl 2 induced DNA damage. Results showed that silymarin at a concentration of 40 µg/mL against NiCl 2 induced DNA damage showed a significant (P< 0.05) decrease in genotoxicity.
Background
The increased use of heavy metal nickel in modern industries results in increased environmental impact. Occupational and environmental exposure to nickel is closely linked to an increased risk of human lung cancer and nasal cancer. Unlike other heavy metal carcinogens, nickel has a weak mutagenic activity.
Objective
Unlike other heavy metal carcinogens, nickel has a weak mutagenic activity. The carcinogenesis caused by nickel is intensively studied, but the precise mechanism of action is not yet known.
Results
Epigenetic changes, activation of hypoxia signaling pathways, and generation of reactive oxygen species (ROS) are considered to be the major molecular mechanisms involved in nickel-induced carcinogenesis.
Conclusion
This review provides insights into current research on nickel-induced carcinogenesis and suggests possible effective therapeutic strategies for nickel-induced carcinogenesis.
EFSA received a request from the Hellenic Food Authority (EFET) for a scientific opinion on the risk to human health from the presence of nickel (Ni) in food, particularly in vegetables. The EFSA Panel on Contaminants in the Food Chain (CONTAM Panel) decided to extend the risk assessment also to drinking water. The reproductive and developmental toxicity in experimental animals was selected as the critical effect for the assessment of chronic effects of Ni. A tolerable daily intake of 2.8 µg Ni/kg body weight (b.w.) per day was derived from a lower 95 % confidence limit for a benchmark dose at 10 % extra risk (BMDL 10) of 0.28 mg/kg b.w. for post-implantation fetal loss in rats. The current dietary exposure to Ni raises concern when considering the mean and 95th percentile chronic exposure levels for all different age groups. The systemic contact dermatitis (SCD) elicited in Ni-sensitive humans after oral exposure to Ni was selected as the critical effect suitable for the assessment of acute effects of Ni. A lowest BMDL 10 of 1.1 µg Ni/kg b.w. was derived for the incidence of SCD following oral exposure to Ni of human volunteers. The CONTAM Panel applied a margin of exposure (MOE) approach and considered an MOE of 10 to be indicative of a low health concern. The MOEs calculated considering the estimated mean and the 95th percentile acute exposure levels were considerably below 10 for all age groups. Overall, the CONTAM Panel concluded that, at the current levels of acute dietary exposure to Ni, there is a concern that Ni-sensitized individuals may develop eczematous flare-up skin reactions. The CONTAM Panel noted the need for mechanistic studies to assess the human relevance of the effects on reproduction and development observed in experimental animals and for additional studies on human absorption of nickel from food, for example in combination with duplicate diet studies.
During the past half-century, incidences of breast cancer have increased globally. Various factors-genetic and environmental-have been implicated in the initiation and progression of this disease. One potential environmental risk factor that has not received a lot of attention is the exposure to heavy metals. While several mechanisms have been put forth describing how high concentrations of heavy metals play a role in carcinogenesis, it is unclear whether chronic, low-level exposure to certain heavy metals (i.e., cadmium and nickel) can directly result in the development and progression of cancer. Cadmium and nickel have been hypothesized to play a role in breast cancer development by acting as metalloestrogens-metals that bind to estrogen receptors and mimic the actions of estrogen. Since the lifetime exposure to estrogen is a well-established risk factor for breast cancer, anything that mimics its activity will likely contribute to the etiology of the disease. However, heavy metals, depending on their concentration, are capable of binding to a variety of proteins and may exert their toxicities by disrupting multiple cellular functions, complicating the analysis of whether heavy metal-induced carcinogenesis is mediated by the estrogen receptor. The purpose of this review is to discuss the various epidemiological, in vivo, and in vitro studies that show a link between the heavy metals, cadmium and nickel, and breast cancer development. We will particularly focus on the studies that test whether these two metals act as metalloestrogens in order to assess the strength of the data supporting this hypothesis.
Nickel compounds are known to be toxic and carcinogenic in kidney and lung. In this present study, we investigated the roles of reactive oxygen species (ROS) and mitochondria in nickel (II) acetate-induced cytotoxicity and apoptosis in the HK-2 human renal cell line. The results showed that the cytotoxic effects of nickel (II) involved significant cell death and DNA damage. Nickel (II) increased the generation of ROS and induced a noticeable reduction of mitochondrial membrane potential (MMP). Analysis of the sub-G1 phase showed a significant increase in apoptosis in HK-2 cells after nickel (II) treatment. Pretreatment with N-acetylcysteine (NAC) not only inhibited nickel (II)-induced cell death and DNA damage, but also significantly prevented nickel (II)-induced loss of MMP and apoptosis. Cell apoptosis triggered by nickel (II) was characterized by the reduced protein expression of Bcl-2 and Bcl-xL and the induced the protein expression of Bad, Bcl-Xs, Bax, cytochrome c and caspases 9, 3 and 6. The regulation of the expression of Bcl-2-family proteins, the release of cytochrome c and the activation of caspases 9, 3 and 6 were inhibited in the presence of NAC. These results suggest that nickel (II) induces cytotoxicity and apoptosis in HK-2 cells via ROS generation and that the mitochondria-mediated apoptotic signaling pathway may be involved in the positive regulation of nickel (II)-induced renal cytotoxicity.
In the present study we used the plasmid relaxation assay, a very sensitive method for detection of DNA strand breaks in vitro, in order to evaluate the role of peptide fragments of histone H2B in DNA strand breakage induced by copper and nickel. We have found that in the presence of peptides modeling the histone fold domain (H2B(32-62) and H2B(63-93)) as well as the N-terminal tail (H2B(1-31)) of histone H2B there is an increased DNA damage by Cu(2+)/H(2)O(2) and Ni(2+)/H(2)O(2) reaction mixtures. On the contrary, the C-terminal tail (H2B(94-125)) seems to have a protective role on the attack of ROS species to DNA. We have rendered our findings to the interactions of the peptides with DNA, as well as with the metal.
We investigated the possible formation of combined toxicity from Ca/Cd exposure on nematode lifespan. Ca exposure at concentrations more than 1.56 mM significantly reduced lifespan, accelerated aging-related declines, and induced severe stress response in wild-type nematodes. Combined Ca (25 mM)/Cd (200 microM) exposure decreased the lifespans compared to Cd (200 microM) exposure; whereas no lifespan differences were found between Ca (1.56 mM)/Cd (200 microM) exposure and Cd (200 microM) exposure. Combined Ca (25 mM)/Cd (200 microM) exposure caused a more significant induction of hsp-16.2::gfp expression, and a more severe increase in oxidative damage than Cd (200 microM) exposure. Moreover, mutation of mev-1, encoding a subunit of succinate dehydrogenase cytochrome b, enhanced the combined Ca/Cd toxicity on lifespan. Furthermore, mutation of daf-16, encoding a fork-head-family transcription factor, enhanced the combined Ca/Cd toxicity on lifespan, and mutation of daf-2, encoding an insulin receptor-like protein, alleviated the combined Ca/Cd toxicity on lifespan.
We investigated a novel inorganic (nickel oxide) nanoparticles as a potential antioxidant in the biosystems. The particles were synthesized using self-propagating high-temperature synthesis (SHS) method at 650 degrees C. The antioxidant property of the nickel oxide particles was investigated in an in vitro system, using modified DPPH method for insoluble solid materials.
Nickel and nickel compounds are widely used in industry. The high consumption of nickel products inevitably leads to occupational and environmental pollution. In occupational settings, exposure to nickel and nickel compounds occurs primarily during nickel refining, electroplating, and welding. The most common airborne exposures to nickel in the workplace are to insoluble nickel species, such as metallic nickel, nickel sulfide, and nickel oxides from dusts and fumes. The chemical and physical properties of nickel and nickel compounds strongly influence their bioavailability and toxicity. The lung and the skin are the principal target organs upon occupational exposure. inhalation exposure is a primary route for nickel-induced toxicity in the workplace. The most important adverse health effects due to occupational exposure to nickel and its compounds are skin allergies, lung fibrosis, and lung cancer. The exact mechanisms of nickel-induced carcinogenesis are not clear. This review summarizes the current knowledge on occupational toxicology of nickel and its compounds. The subtopics include: chemical and physical properties, uses, occupational exposures, occupational exposure limits, toxicokinetics, biological monitoring, acute toxicity, chronic toxicity, genotoxicity, reproductive toxicity, carcinogenicity, molecular mechanisms of carcinogenesis, and gaps in knowledge.
IARC is reassessing the human carcinogenicity of nickel compounds in 2009. To address the inconsistencies among results from studies of water-soluble nickel compounds, we conducted a weight-of-evidence analysis of the relevant epidemiological, toxicological, and carcinogenic mode-of-action data. We found the epidemiological evidence to be limited, in that some, but not all, data suggest that exposure to soluble nickel compounds leads to increased cancer risk in the presence of certain forms of insoluble nickel. Although there is no evidence that soluble nickel acts as a complete carcinogen in animals, there is limited evidence that suggests it may act as a tumor promoter. The mode-of-action data suggest that soluble nickel compounds will not be able to cause genotoxic effects in vivo because they cannot deliver sufficient nickel ions to nuclear sites of target cells. Although the mode-of-action data suggest several possible non-genotoxic effects of the nickel ion, it is unclear whether soluble nickel compounds can elicit these effects in vivo or whether these effects, if elicited, would result in tumor promotion. The mode-of-action data equally support soluble nickel as a promoter or as not being a causal factor in carcinogenesis at all. The weight of evidence does not indicate that soluble nickel compounds are complete carcinogens, and there is only limited evidence that they could act as tumor promoters.
Human peripheral lymphocytes from whole blood cultures were exposed to either soluble form of nickel carbonate hydroxide (NiCH) (0-60 microM), or of nickel subsulfide (Ni(3)S(2)) (0-120 microM), or of nickel oxide (NiO) (0-120 microM), or nickel sulfate (NiSO(4)) (0-120 microM) for a short duration of 2 h. The treatments occurred 46 h after the beginning of the cultures. The cultures were harvested after a total incubation of 72 h, and sister-chromatid exchange (SCE), replication index (RI), and mitotic index (MI) were measured for each nickel compound. The soluble form of NiCH at 30 microM but those of Ni(3)S(2) and NiO at 120 microM produced significant increase in the SCE per cell compared to the control value, whereas NiSO(4) failed to produce any such significant increase. Except NiSO(4), the soluble forms of NiCH, Ni(3)S(2), and NiO produced significant cell-cycle delay (as measured by the inhibition of RI) as well as significant inhibition of the MI at respective similar concentrations as mentioned above. Pretreatment of human blood lymphocytes with catalase (H(2)O(2) scavenger), or superoxide dismutase (superoxide anion scavenger), or dimethylthiourea (hydroxyl radical scavenger), or deferoxamine (iron chelator), or N-acetylcysteine (general antioxidant) inhibited NiCH-induced SCE, and changes in RI and MI. This suggests the participation of oxidative stress involving H(2)O(2), the superoxide anion radical, the hydroxyl radical, and iron in the NiCH-induced genotoxic responses. Cotreatment of NiCH with either verapamil (inhibitor of intracellular calcium ion ([Ca(2+)](i)) movement through plasma membranes), or dantrolene (inhibitor of [Ca(2+)](i) release from sarcoplasmic reticulum), or BAPTA (Ca(2+) chelator) also inhibited the NiCH-induced responses. These results suggest that [Ca(2+)](i) is also implicated in the genotoxicity of NiCH. Overall these data indicate that various types of oxidative stress including iron-mediated oxidative stress involving the Fenton-Haber/Weiss reaction, and alterations in calcium homeostasis are involved in the genetic damage produced by the soluble form of NiCH.
The vast industrial use of nickel has led to environmental pollution by the metal and its by-products during production, recycling, and disposal. Nickel is a known hematotoxic, immunotoxic, hepatotoxic, pulmotoxic, and nephrotoxic agent. Allergic skin reactions are common in individuals who are sensitive to nickel. This article presents a selective review on nickel and its effect on certain metabolically active peripheral tissues of human and animals. The subtopics include nickel sources and uses, exposure pathways, transport, excretion, general health effects, and specific acute and chronic nickel toxicities in peripheral tissues like liver, lungs, and kidneys. The review particularly addresses the nickel-induced generation of reactive oxygen species and increased lipid peroxidation in various metabolically active tissues in humans and animals, and the possible role of vitamin c as a protective antioxidant.
Rat liver nuclei generate superoxide radicals in the presence of NADPH. Active oxygen species induced nicks in nuclear DNA. This was prevented by superoxide dismutase and catalase as well as by anaerobiosis. EDTA-Fe3+ dramatically increased the active oxygen-dependent DNA nicking.
Toxicity testing in AS52 cells (24-hr exposures) gave LC50 values of 2 to 130 micrograms Ni/ml for particulate nickel compounds and 45 to 60 micrograms Ni/ml for water-soluble salts (NiCl2, NiSO4, Ni(CH3COO)2). The Ni(OH)2, NiCO3, and sulfides (Ni3S2, Ni7S6, "amorphous NiS") exhibited similar toxicities (LC50's of 2 to 8 micrograms Ni/ml), while three nickel oxides were more variable and less toxic (LC50's of 18 to 130 micrograms Ni/ml). Most compounds displayed nuclear to cytoplasmic nickel ratios of approximately 1:1.5 to 1:5 (except approximately 1:20 for nickel salts). At the LC50's, a 75-fold range in exposure levels occurred compared to a 10-fold range in cytoplasmic and nuclear nickel concentrations, [Ni]. Cellular nickel distribution indicated three groupings: inert compounds (green NiO, lithium nickel oxide, relatively low nuclear and cytosolic [Ni]); water-soluble salts (very low nuclear [Ni]; high cytosolic [Ni]), and slightly soluble compounds (relatively high cytosolic and nuclear [Ni]). Nickel compounds are considered to be only weak or equivocal mutagens. In this study, a low but significant increase in mutation rate at the gpt locus was shown. Although the results would not be sufficient to deem nickel compounds mutagenic by traditional criteria, characterization by PCR analysis indicated that the spontaneous and nickel-induced mutants exhibited different and compound-specific mutational spectra (thus confirming nickel compound involvement). The results reported illustrate some of the methodologic problems involved in testing "weak" mutagens and indicate that alternative approaches may be necessary in classifying the mutagenicity of nickel and other compounds.
Nickel ions have been reported to exhibit differential effects on distinct subtypes of voltage-activated calcium channels. To more precisely determine the effects of nickel, we have investigated the action of nickel on four classes of cloned neuronal calcium channels (α1A, α1B, α1C, and α1E) transiently expressed in Xenopus oocytes. Nickel caused two major effects: (i) block detected as a reduction of the maximum slope conductance and (ii) a shift in the current-voltage relation towards more depolarized potentials which was paralleled by a decrease in the slope of the activation-curve. Block followed 1:1 kinetics and was most pronounced for α1C, followed by α1E > α1A > α1B channels. In contrast, the change in activation-gating was most dramatic with α1E, with the remaining channel subtypes significantly less affected. The current-voltage shift was well described by a simple model in which nickel binding to a saturable site resulted in altered gating behavior. The affinity for both the blocking site and the putative gating site were reduced with increasing concentration of external permeant ion. Replacement of barium with calcium reduced both the degree of nickel block and the maximal effect on gating for α1A channels, but increased the nickel blocking affinity for α1E channels. The coexpression of Ca channel β subunits was found to differentially influence nickel effects on α1A, as coexpression with β2a or with β4 resulted in larger current-voltage shifts than those observed in the presence of β1b, while elimination of the β subunit almost completely abolished the gating shifts. In contrast, block was similar for the three β subunits tested, while complete removal of the β subunit resulted in an increase in blocking affinity. Our data suggest that the effect of nickel on calcium channels is complex, cannot be described by a single site of action, and differs qualitatively and quantitatively among individual subtypes and subunit combinations.
The U.S. National Toxicology Program has shown clear evidence of carcinogenicity of nickel subsulfide (Ni(3)S(2)) and some evidence of carcinogenicity of NiO (green) in rats. In the present study, DNA damage in cultured cells and in lungs of rats induced by nickel compounds was investigated to clarify the mechanism of nickel carcinogenesis. In cultured HeLa cells, Ni(3)S(2) induced a significant increase in 8-hydroxydeoxyguanosine (8-OH-dG) formation, whereas NiO (black), NiO (green), and NiSO(4) did not. On the other hand, in rats, intratracheal instillation of all these nickel compounds significantly increased 8-OH-dG content in the lungs. The disparities in DNA damage between cultured cells and animals could be accounted for by two different mechanisms for nickel-induced oxidative DNA damage in lungs of rats. One is direct oxidative DNA damage: Ni(II) enters the cells and then reacts with endogenous and/or nickel sulfide-produced hydrogen peroxide (H(2)O(2)) to give reactive oxygen species that cause DNA damage. This mechanism is supported by oxidative damage to isolated DNA treated with Ni(II) and H(2)O(2). The other mechanism is indirect oxidative DNA damage due to inflammation. This double mechanism for DNA damage may explain the relatively high carcinogenic risk associated with Ni(3)S(2).
DNA damage (alkaline filter elution) and sister chromatid exchange (SCE) frequencies were measured in lymphocytes of 39 welders and 39 controls. The welders showed a significantly higher rate of DNA single-strand breakages and significantly elevated SCE values. These results are not in accordance with those of a former study in which only DNA-protein cross-links were measured. The different results may be explained on the basis of different exposure levels for chromium(VI) and nickel. Both methods are not specific but sensitive enough to measure genotoxic damage after occupational exposure to chromium(VI) and nickel in the range of threshold values for the workplace on a collective basis. Additionally, the results indicate that DNA single-strand breakage and DNA-protein cross-links show different increases depending on the exposure levels for chromium and nickel.
Single-strand breaks were observed in rat lung and kidney after acute treatment of animals with CdCl2 (4 mg/kg body weight) injected intraperitoneally and NiCl2 (44.4 mg/kg body weight) injected subcutaneously. In the rat liver, no single-strand breakage was evident with those doses in single and combined metal treatments. The most susceptible tissue in rats to cadmium or nickel chloride treatment was the lung tissue. The single-strand breaks were higher in cadmium treatment than in nickel treatment in the rat lung. Also the response to cadmium treatment was obtained earlier than nickel. Rat kidney was also responsive to cadmium treatment. However, the response, although statistically significant, was much lower than the one obtained in rat lung. The combined treatment, which was done by administrating cadmium prior to nickel administration, reduced the number of single-strand breaks significantly and reversed them to control values in rat lung and kidney. This study confirms that cadmium and nickel create single-strand breaks when administered alone in the rat lung. This effect, which was seen in the single metal treatments, was reduced in the combined treatments.
The authors carried out a Cytogenetic examination of chromosomal aberrations of peripheral lymphocytes (100 cells evaluated in each sample) with simultaneous monitoring of the level of exposure by means of determination of nickel in the urine, serum and hair. The series included 21 workers occupationally exposed to nickel at two workshops producing NiO (6 persons) and NiSO4 (15 persons) in a chemical plant. At the same time a comparable control group i.e., 19 workers of the same chemical plant but without any direct occupational nickel exposure (clerks, service men, etc.), were examined in the same way.In the exposed group chromosomal aberrations of peripheral lymphocytes were detected with an average value of 6.41 ± 1.9% (range 2–14%); in the group producing NiO it was, on the average, 9.5+3.2% (range 7–14%) whereas in the NiSO4 production workers it was only 5.2± 1.9% (range 2–10%). There was a dependence of chromosomal aberrations of peripheral lymphocytes on the exposure time and on the nickel content of the biological material. Significantly increased values (in contrast to the normal value of chromosomal aberrations of peripheral lymphocytes, up to 2%) were detected in the control group as well (average value of 4.05 ± 2.27%, range 1–10%). The authors explain this fact by the nickel-polluted environment of the whole observed chemical plant.
The ligand tris-(hydroxymethyl)-aminomethane, or ∗2-amino-2-(hydroxymethyl)1,3-propanediol, forms brightly colored, air-stable, crystalline complexes with the first row bi- and trivalent transition and representative metal salts from manganese to zinc.These compounds exhibit unusual bio-, organo-, and inorganochemical activities. Until this time they have been neither isolated nor characterized. They have the general formula: M(NTRHm)(NTRHn)∗Xp, where X is Cl−, m and n are 0, 2 or 3, and p is 1 or 2, depending on the charge on the central metal cation[1].Analytical and spectral data indicate that within the first coordination sphere of each complex the symmetry is either Td, C3, or Oh, and the corresponding coordination numbers are four, five and six, respectively.The X-ray powder diffraction patterns for these compounds are in all cases sharp, regular, and intense, indicating the existence of highly crystalline materials, some of which contain geometrical isomers.The compounds are both low and high spin.Conductance measurements indicate a 1:2 electrolyte in the case of (Mn(NTRH3)2)Cl2; a 1:1 electrolyte in the cases of (Fe(NTRH3)(NTRH2)Cl)Cl, (Ni(NTRH3)2Cl)Cl, (Cu(NTRH3)(NTRH2))Cl, and (Zn(NTRH3)2Cl)Cl; and non-electrolytes in the cases of (Co(NTRH2)Cl)2 and (Cu(NTRH2)Cl)2.
We report a procedure allowing the detection and counting of free 3′-OH DNA strand extremities in single cells in situ. Terminal transferase (TdT) catalysed the incorporation of 3H-dGMP into fixed nuclei of human colonic adenocarcinoma cells (HT29), using free 3′-OH ends as initiator. Radioactivity was detected by autoradiography and determined quantitatively with a rapid image-processing system for grain counting. The initiator activity for TdT increases with the dose of γ-rays in the dose range 2·5–20 Gy.
Significant concentrations (1-10 mM) of nickel(II) were found in solution after incubation of the potent carcinogen nickel subsulfide in 0.05 M Tris-HCl, pH 7.4, solutions containing DNA, rat liver microsomes, and NADPH. The presence of NADPH decreased the rate of solubilization of nickel subsulfide. The solubilized nickel exhibited electronic absorption spectra and magnetic moments characteristic of octahedral nickel(II). The solubilized nickel(II) bound to DNA with an apparent equilibrium constant of 730 M/sup -1/ and with a saturation binding value of one nickel per 2.4 nucleotides. Microsomes lowered the saturation binding of nickel to DNA but dramatically increased the amount of nickel-DNA complex stable to precipitation with salt and poly-(ethylene glycol). The amount of protein associated with DNA precipitated from protein-extracted solutions correlated with the amount of nickel bound to DNA. These results suggest that microsomes mediate the binding of nickel to DNA by forming a stable ternary protein-nickel(II)-DNA complex.
Nickel compounds are known human carcinogens, but the exact molecular mechanisms of nickel carcinogenesis are not known. Due to their abundance, histones are likely targets for Ni(II) ions among nuclear macromolecules. This paper reviews our recent studies of peptide and protein models of Ni(II) binding to histones. The results allowed us to propose several mechanisms of Ni(II)-inflicted damage, including nucleobase oxidation and sequence-specific histone hydrolysis. Quantitative estimations of Ni(II) speciation, based on these studies, support the likelihood of Ni(II) binding to histones in vivo, and the protective role of high levels of glutathione. These calculations indicate the importance of histidine in the intracellular Ni(II) speciation.
Cells from the thigh muscles of normal fetal rats proliferated rapidly and indefinitely in a medium containing adult rat "plasma" and a normal free-calcium concentration, but they could not proliferate in calcium-deficient plasma medium. As the animals grew older, the cells became increasingly less able to proliferate even in normal (high-calcium) plasma medium, though they retained the potential to proliferate in a more conventional medium containing fetal bovine serum. By contrast, neoplastic adult cells from malignant rhabdomyosarcomas (induced by Ni3S2) proliferated rapidly and indefinitely in both normal and low-calcium plasma medium
1. Glutathione redox cycle alterations induced by acute treatment of nickel, cadmium and copper, have been investigated in liver and kidney of adult male rats. 2. In liver, nickel treatment decreased GSH and GSSG levels, followed by a significant rebound in GSH content. Copper produced drastic reduction in the GSH/GSSG ratio, while cadmium treatment altered GSSG concentrations. 3. In kidney, the glutathione redox cycle remained unaltered after cadmium or nickel exposure, whereas copper caused similar changes to those observed in liver. 4. Hepatic glucose-6-P dehydrogenase and GSSG-reductase activities decreased after copper or nickel injection. GSH-S-transferase activity was altered in various ways, depending on the organ and the metal.
A total of 39 electric welders exposed to chromium and nickel were compared with 18 controls standardized for age, smoking habits and sex with respect to the frequency of sister chromatid exchange (SCE) and of DNA strand breakage and cross-linking (measured by the method of alkaline filter elution) in their blood lymphocytes. A significant correlation was found between the frequency of SCE and of individual DNA strand breakage and the concentration of chromium in the urine. Less DNA from the welders than from the control group was eluted through the two filter types used (polycarbonate and polyvinylidene fluoride filters). This must be interpreted as resulting from the presence of DNA-protein cross-links, which has the secondary effect of leading to a relative reduction in the measurable frequency of strand breakage amongst the welders. The present results are in good agreement with in vitro and in vivo investigations that confirm the importance of DNA-protein cross-links for the carcinogenic effect of chromium.
The mortality experience of 716 male hydrometallurgical nickel refinery employees who worked at Sherritt Gordon Limited in
Fort Saskatchewan, Alberta for at least 12 continuous months during the years 1954 to 1978 was examined. Mortality ascertainment
was obtained utilizing the Canadian Mortality Data Base maintained by Statistics Canada and covered the years 1954 through
1984. Cause-specific mortality analyses were accomplished using male, age and calendar-year adjusted death rates for Canada
and the province of Alberta. Total mortality was significantly below expectation (27 observed vs. 47 expected). Statistically
significant fewer observed deaths were found for circulatory disease while multiple myeloma demonstrated a statistically significant
increase of observed deaths. No deaths due to nasal cavity or paranasal sinus cancer were detected. Only one lung cancer death
was found with three deaths expected (SMR 33). No association was found in this study between exposure to nickel concentrate
or metallic nickel and the subsequent development of respiratory cancer.
A method is described whereby any given chromosome spread selected by light microscopy can be transferred to a grid and studied by electron microscopy.
We report a procedure allowing the detection and counting of free 3'-OH DNA strand extremities in single cells in situ. Terminal transferase (TdT) catalysed the incorporation of 3H-dGMP into fixed nuclei of human colonic adenocarcinoma cells (HT29), using free 3'-OH ends as initiator. Radioactivity was detected by autoradiography and determined quantitatively with a rapid image-processing system for grain counting. The initiator activity for TdT increases with the dose of gamma-rays in the dose range 2.5-20 Gy.
The ability of the physiologically essential divalent metals calcium and magnesium to inhibit the tumorigenic activities of lead and nickel towards the lungs of strain A mice was investigated. The tumorigenic salts lead(II) subacetate and nickel(II) acetate were injected i.p. at their maximal tolerated doses (0.04 mmol/kg/injection of each metal) for a total of 24 injections, whenever possible. Calcium(II) acetate and magnesium(II) acetate were administered in the same preparation along with the lead and nickel salts at molar doses of approximately 1, 3, 10, and 30 times the maximal tolerated dose of the tumorigen. The animals were sacrificed 30 weeks after the first injection, and the lung tumors were counted. The lead and nickel salts, administered alone, each produced a significant increase in the observed number of lung adenomas per mouse. When administered with any of the doses of calcium acetate or magnesium acetate tested, neither lead subacetate nor nickel acetate showed any significant tumorigenic activity. Calcium acetate alone (total dose, 11 mmol/kg of body weight) appeared to yield a significant rise in lung adenomas observed. The results indicate an antagonism between magnesium and calcium and the tumorigenic metals nickel and lead.
Significant concentrations (1-10 mM) of nickel(II) were found in solution after incubation of the potent carcinogen nickel subsulfide in 0.05 M Tris-HCl, pH 7.4, solutions containing DNA, rat liver microsomes, and NADPH. The presence of NADPH decreased the rate of solubilization of nickel subsulfide. The solubilized nickel exhibited electronic absorption spectra and magnetic moments characteristic of octahedral nickel(II). The solubilized nickel(II) bound to DNA with an apparent equilibrium constant of 730 M-1 and with a saturation binding value of one nickel per 2.4 nucleotides. Microsomes lowered the saturation binding of nickel to DNA but dramatically increased the amount of nickel-DNA complex stable to precipitation with salt and poly-(ethylene glycol). The amount of protein associated with DNA precipitated from protein-extracted solutions correlated with the amount of nickel bound to DNA. These results suggest that microsomes mediate the binding of nickel to DNA by forming a stable ternary protein-nickel(II)-DNA complex.
The effect of various metal compounds on the DNA of Chinese hamster ovary (CHO) cells was studied. Both NiCl2 and crystalline NiS caused DNA strand breaks in cultured CHO cells, whereas amorphous NiS did not. Strand breaks were quantitated
by determining the number average molecular weight of DNA following treatment with the metal compounds. Exposure of cells
to crystalline NiS, CoS, CdS, AgS, CuS and Ni3S2 at 10 μg/ml for 24 h also induced DNA strand breaks. Similar exposure to activated charcoal, which was also actively phagocytosed,
failed to cause any effect on the DNA of CHO cells. In the case of NiCl2 and NiS the effect was shown to be both time and dose dependent. Other soluble metal compounds such as HgCl2, CaCrO4, and CdCl2 also decreased the molecular weight of DNA while MnCl2, ZnCl2 and FeCl2 caused no significantly detectable change in DNA molecular weight. These effects, which occur at low metal concentrations
suggest that nickel and other metals which cause cellular transformation have a very selective and specific effect upon DNA.
Seven particulate nickel compounds were studied for their cell transformation activity using cultured Syrian hamster embryo cells and for their phagocytotic activity in cultured Chinese hamster ovary cells. The crystalline nickel compounds (αNi3S2, αNiS, and Ni3Se2) had significantly more cell transforming activity and were more actively phagocytized than the other nickel compounds examined (amorphous NiS, metallic Ni, Ni3O2, and NiO). Therefore, the crystalline structure of nickel compounds is one factor influencing their toxic activity upon biological systems. A second influencing factor was the particle size of the water-insoluble nickel compounds. Particles of crystalline αNiS ranging from 2 to 4 μm were phagocytized six times more than αNiS particles having mean diameters of 5–6 μm. Differences in amorphous NiS particle size had little effect on its already low susceptibility to be phagocytized by cells and ability to cause a reduction of cell plating efficiency. The presence of Mn dust inhibited the neoplastic transformation of crystalline nickel sulfide and also reduced the phagocytosis of crystalline αNiS and αNi3S2 particles by cultured cells. The phagocytosis of crystalline NiS particles was inhibited by the presence of amorphous NiS, Mn or MnCl2. Therefore, the presence of noncarcinogenic metals which are not themselves actively phagocytized diminishes the transforming effects of crystalline metal compounds probably by reducing their internalization. Various metabolic inhibitors such as dansylcadaverine, cycloheximide, and actinomycin D reduced the phagocytosis of crystalline αNiS.
7,8-Dihydro-8-oxo-2′p-deoxyguanosine (8-oxo-dG) was measured as an indicator of nickel-induced oxidative base damage in the
presence of H2O2. Heterochromatic proteins isolated from Chinese hamster liver cells enhanced the formation of 8-oxo-dG induced by NiCl2 and H2O2 in vitro, whereas dichromatic proteins inhibited this reaction. The inhibitory effect of euchromatic proteins on dG oxidation may
be due to the oxygen radical scavenging effects of low molecular weight protein-rich fractions. Gel electrophoresis confirmed
that histone Hx was present at a higher concentration in heterochromatin than in euchromatin. It is believed that the presence
of nickel-protein complexes in cells is crucial for the formation of reactive oxygen species (ROS). We found that Ni2+ binds to histone Ht and core histones as determined by 63Ni autoradiography of proteins on nitrocellulose membranes. In vitro studies showed that commercially purified histone H1, and to a considerably lesser extent core histones, enhanced the N1C12 and H2O2 catalyzed formation of 8-oxo-dG in a reaction containing free dG base. Since histone Ht is a lysine- and alanine-rich protein,
the levels of 8-oxo-dG induced by NiCl2 and H2O2 were studied in the presence of these amino acids and found to be enhanced by them. These results suggest that nickel may
specifically produce oxidative DNA damage in heterochromatin because of the nature of its binding to histone H1 and core histones. This selective oxidation of genetically inactive heterochromatin may explain why nickel compounds which
generate oxygen radicals and oxidize DNA bases are inactive in most gene mutation assays.
The carcinogenic potency of nickel compounds depends on the ability of nickel ions to enter target cells. The presumptive preventive potential of several metals against nickel-induced cancer may depend on their capacity to inhibit nickel uptake. Surface binding and uptake of 63Ni2+ in immortalized human kidney epithelial (IHKE) cells suspended in a salts/glucose minimal medium was studied at 0.085 mM nickel. Nickel uptake, after a rapid phase of about 2 h, continued at a slower rate for several hours. Nicardipine (50 microM) decreased uptake to about 25% of control values. Ionomycin (3 microM) increased uptake 4- to 5-fold. Nickel uptake into IHKE cells was decreased by metal cations. In the absence of ionomycin, this effect followed the order Zn > Cd > Co > Mn > Mg > Ca. In the presence of ionomycin the order was Zn > Cd > Co > Mn > Ca > Mg. These metals inhibited uptake more strongly than binding to the cell surface. However, Co2+ reduced surface binding strongly in ionomycin-potentiated uptake. With no ionomycin present, 0.15 mM Zn2+, 1 mM Mn2+, 4 mM Mg2+ or 70 mM Ca2+ caused 80-85% inhibition of nickel uptake. In the absence of ionomycin, calcium was a weaker inhibitor of nickel uptake than magnesium. In the presence of ionomycin, calcium was a stronger inhibitor than magnesium. The results indicate that nickel can be taken up through calcium channels in IHKE cells. It is suggested that ionomycin-potentiated transport mechanisms, under the conditions applied, are different from normal mechanisms of transport functioning in the absence of ionomycin. Different metals, essential and non-essential, seem to be inhibitors or competitors for the transport mechanisms.
L-929 mouse chromosomes prepared for electron microscopy have been treated with MspI, EcoRI, and HaeIII restriction endonucleases (REs). RE-induced nicks were amplified with exonuclease III to obtain single-stranded DNA (ss-DNA) motifs. The ss-DNA produced was enough to permit hybridization of a series of random oligonucleotides. These can be used as primers, which are extended by the Klenow fragment using non-isotopic labelled dUTP. The incorporation of biotinylated dUTP is detected with a gold-tagged streptoavidin as the reporter molecule. This allows, in mouse chromosomes, the detection of different rates of sensitivity to the digestion with specific REs in distinct intraheterochromatic DNA subsets. In addition, these results show that enzymatic production of ss-DNA seems to be adequate for electron microscopy work since the chromatin fiber is preserved better than in denatured DNA produced with heat, NaOH, or formamide.
Formation of DNA-protein cross-links and oxidatively damaged DNA bases was investigated with the use of alkaline elution and gas chromatography/mass spectrometry techniques in the nuclei from kidneys of rats 3 and 18 h after a single iv injection of the NiII(His)2 complex (NiHis), nickel(II) acetate (NiAcet), or L-histidine (His). Administration of 20 mumol of NiHis/kg body wt caused the formation of DNA-protein cross-links and significantly increased levels of oxidatively damaged DNA bases, including 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua; 3.5-fold vs the control value) 3 h postinjection and 8-oxoguanine (2.6-fold), cytosine glycol (2.5-fold), 8-oxoadenine (2-fold), and FapyGua (1.9-fold) 18 h postinjection. Injection of 20 mumol of NiAcet/kg body wt enhanced the cross-linking to a lesser extent than NiHis and did not significantly increase the amounts of modified DNA bases over the control levels. Forty micromoles of His per kilogram body wt alone caused a marked DNA-protein cross-linking effect and increased the amount of 4,6-diamino-5-formamidopyrimidine (2-fold vs the control) 3 h, but not 18 h, after treatment. The DNA base derivatives found were typical products of hydroxyl radical (.OH) attack on DNA. Formation of the cross-links may also be attributed to .OH, although other mechanisms, e.g., formation of ternary complexes of Ni(II), cannot be excluded. The present in vivo study confirms the conclusion of our former in vitro experiments that His enhances Ni(II)-mediated oxidative damage to DNA and chromatin.(ABSTRACT TRUNCATED AT 250 WORDS)
Chinese hamster Don cells were treated with 10 mM hydrogen peroxide. DNA strand breaks induced by hydroxyl radicals were amplified in 3' termini by an exonuclease III digestion, resulting in single stranded DNA motifs. In situ detection of these motifs was performed on chromatin fibres of isolated whole-mounted nuclei and chromosomes by a random priming procedure, using biotinylated-dUTP which bound a gold-tagged streptavidin. This approach facilitated the location of hydroxyl radical induced DNA breaks, specifically on 20-30 nm diameter chromatin fibres, by transmission electron microscopy.
The effect of nickel (Ni) on the enzymatic activities in the pancreas of mice was studied. Administration of Ni at the dose of 5 mg Ni/kg increased the trypsin activity and decreased carboxypeptidase A activity, but did not affect the activities of chymotrypsin, carboxypeptidase B, amylase, and lipase. Increases in Ca concentrations in the pancreas after Ni administration were observed. In the pancreatic slice experiments, Ni treatment showed a slight decrease in trypsin activity and remarkable decreases in chymotrypsin and carboxypeptidase A activities, and Ca treatment induced increases in the activities of trypsin and carboxypeptidase A. These results suggest that the increase in trypsin activity in the pancreas after Ni administration results from the activation of trypsinogen by the Ca ion and that the decrease in carboxypeptidase A activity is based on the inhibitory effect of Ni on carboxypeptidase A activity.
The early epidemiological data indicated different carcinogenic risks from inhalation of different nickel compounds, but it was not clear what characteristics governed the intrinsic carcinogenic hazard of the various nickel compounds. Based on the earlier results, all soluble and insoluble nickel compounds were assumed to have the same carcinogenic mechanism albeit different potencies. Recent in vivo and in vitro studies challenged this assumption. In this paper an attempt is made to integrate the most relevant human, animal, and in vitro data into a general model that can help understand the different carcinogenic potentials of the various nickel compounds. In this perspective, it is recognized that there are two main components that could contribute to the development of lung cancer via exposure to certain nickel compounds. The first component corresponds to the heritable changes (genetic or epigenetic) derived from the direct or indirect actions of nickel compounds. The second component may be the promotion of cell proliferation elicited by certain nickel compounds. The different contributions of three nickel compounds to these two components are presented. This paper emphasizes the importance of recognizing the individuality of the different nickel species in reaching regulatory decisions and the fact that different risk assessment considerations may apply for compounds that appear to produce immortality and cancer by genetic/epigenetic mechanisms (like nickel subsulfide), compounds that may present a threshold for the induction of tumors in rats (like high-temperature nickel oxide), or compounds that may only have an enhancing effect on carcinogenicity (like nickel sulfate).
A potentiometric and spectroscopic (UV/vis and CD) study of Cu(II) and Ni(II) binding to the N-terminal pentadecapeptide of human protamine HP2 (HP2(1-15)) was performed. The results indicate that the N-terminal tripeptide motif Arg-Thr-His is the exclusive binding site for both metal ions at a metal to HP2(1-15) molar ratio not higher than 1. The very high value of protonation-corrected stability constant (log *K) for Ni(II)-HP2(1-15) complex, -19.29, indicates that HP2 has the potential to sequester Ni(II) from other peptide and protein carriers, including albumin. The same is likely for Cu(II) (log *K = -13.13). The CD spectra of Cu(II) and Ni(II) complexes of HP2(1-15) indicate that the N-terminal metal binding affects the overall conformation of the peptide that, in turn, may alter interaction of HP2 with DNA. These results imply HP2 as a likely target for the toxic metals Ni(II) and Cu(II).
The present study was designed to clarify the mechanism of nickel (Ni) uptake in primary cultures of rat hepatocytes. Exposure of the hepatocytes to Ni (2-50 microM; as NiCl2) for up to 6 h was not cytotoxic, as assessed by the tetrazolium-based dye (MTT) assay. Hepatocytes were treated with 10 microM NiCl2 in the absence or presence of calcium (Ca) and magnesium (Mg) (1 mM). Ni uptake was increased by 19% in medium lacking Mg or Ca and was increased by 37% in Ca- and Mg-free medium. The role of Ca channels on Ni uptake by the hepatocytes was investigated. Pretreatment with nicardipine or verapamil (200 microM), potent inhibitors of Ca channels, decreased Ni uptake by 20%. This effect was only observed when the cells were incubated in the absence of Ca. Pretreatment with vasopressin (100 nM), a well-known Ca channel agonist, significantly increased Ni uptake by the hepatocytes (24%). To determine the involvement of carrier-mediated processes on Ni uptake, the effect of temperature was also investigated. At 4 degrees C the Ni uptake was decreased by 20% compared to uptake at 37 degrees C. These results indicate that Ni uptake by the hepatocytes occurs, at least in part, through the Ca channel transport processes. Further study will be required to assess what other mechanisms are involved.
Styrene-7,8-oxide, an intermediate of styrene, is a known alkylating mutagen. The present study was carried out to investigate the influence of duration of exposure to styrene-7,8-oxide (styrene oxide) on induction of sister chromatid exchanges (SCEs) and inhibition of cell-cycle kinetics using cultured human blood lymphocytes in vitro. Phytohemagglutinin-stimulated whole-blood lymphocyte cultures obtained from heparinized whole blood from healthy donors were exposed to 100 microM styrene oxide for 22, 36, 48 and 72 h. A reduction of SCEs induction with increase in duration of exposure to styrene oxide was observed, i.e. a clear significant inverse relationship between exposure time and frequencies of SCEs induction due to styrene oxide was obtained. Styrene oxide induces significant elevations in unscheduled DNA synthesis DNA repair as well as S-phase synthesis in human blood lymphocytes in vitro, depending on the duration of exposure. The decrease in the induction of SCEs due to styrene oxide with increasing duration of its exposure may be principally due to an increased DNA repair and partly due to an increasing metabolic transformation to styrene glycol with increasing duration of its exposure as well as to some extent due to cell death at the maximum period of exposure. i.e. 72 h. Although the proliferations of lymphocytes exposed to 100 microM styrene oxide were significantly inhibited at different durations of exposure, no linear relationship between the replication index and the duration of exposure was noticed (r = 0.47, p > 0.05). Similarly, there was no relationship between replication index and SCE frequency (r = -0.36, p > 0.05), suggesting that these two parameters may reflect two different endpoints for the cytogenotoxic effects of styrene oxide.
In order to detect the genotoxic effects of nickel (Ni) and chromium (Cr) contained in welding fumes on humans, sister chromatid exchanges (SCEs) frequency in lymphocytes was determined in the blood samples derived from 39 stainless steel welders and compared with the data obtained from 22 sex and age matched unexposed controls. The frequency of SCEs was higher in the welders than in the controls. Smoking proved to be a significant, positive predictor for SCE frequency in the controls but not in the welders. Significant correlation between SCE and chromium concentrations in urine of smoking welders was found. A possible synergism between chromium exposure and smoking is discussed. Neither age and urine nickel concentrations nor duration of exposure was a significant predictor for SCE frequency.
DNA damage (alkaline filter elution) and sister chromatid exchange (SCE) frequencies were measured in lymphocytes of 39 welders and 39 controls. The welders showed a significantly higher rate of DNA single-strand breakages and significantly elevated SCE values. These results are not in accordance with those of a former study in which only DNA-protein cross-links were measured. The different results may be explained on the basis of different exposure levels for chromium(VI) and nickel. Both methods are not specific but sensitive enough to measure genotoxic damage after occupational exposure to chromium(VI) and nickel in the range of threshold values for the workplace on a collective basis. Additionally, the results indicate that DNA single-strand breakage and DNA-protein cross-links show different increases depending on the exposure levels for chromium and nickel.
One general signalling mechanism used to transfer the information delivered by agonists into appropriate intracellular compartments involves the rapid redistribution of ionised calcium throughout the cell, which results in transient elevations of the cytosolic free Ca2+ concentration. Various physiological stimuli increase [Ca2+]i transiently and, thereby, induce cellular responses. However, under pathological conditions, changes of [Ca2+]i are generally more pronounced and sustained. Marked elevations of [Ca2+]i activate hydrolytic enzymes, lead to exaggerated energy expenditure, impair energy production, initiate cytoskeletal degradation, and ultimately result in cell death. Such Ca(2+)-induced cytotoxicity may play a major role in several diseases, including neuropathological conditions such as chronic neurodegenerative diseases and acute neuronal losses (e.g. in stroke).
We have evaluated a genotoxicity assay that combines in situ end-labeling, colloidal gold tagging and electron microscopy in order to adapt it to the measurement of in vitro biomaterial-induced genotoxicity. Human lymphocytes were cultured in semi-physiological medium which had been previously exposed to biomaterial extracts of commercially pure titanium following ISO standards. In order to visualize the location of induced DNA strand breaks, cells were then exposed to exonuclease III which partially digests and amplifies lesions by releasing nucleotides at free 3' hydroxyl ends from nicked double-stranded DNA. The resulting single-stranded DNA was allowed to hybridize with short oligonucleotides of random sequences including biotinylated dUTP. After random priming using Escherichia coli DNA polymerase I, incorporation of biotin-dUTP was detected by immunogold binding to the chromatin. Cells exposed to a mutagenic concentration of methyl methanesulfonate, as a positive control, showed a significantly higher and stronger gold staining than both titanium-exposed and unexposed specimens. This assay allows a precise localization and quantification of both in vitro DNA breakage and DNA repair. It could provide a powerful tool for rapid assessment of the genotoxic potential of new biomaterials.
Nickel chloride (NiCl2) induced lactate dehydrogenase (LDH) release and lipid peroxidation (LPO) in rat renal cortical slices in vitro in a concentration- (0-2 mM) and time- (0-4 hr) dependent manner, with initial significant LDH release occurring as early as 1 hr, whereas significant increase in LPO started 3 hr after exposure, suggesting that LPO results from renal cell injury. Both NiCl2-induced LDH release and LPO were prevented significantly by glutathione and dithiothreitol, suggesting that NiCl2-induced renal cell injury is dependent on thiols. However, such injury is not dependent solely on thiols, because (a) these thiols failed to inhibit completely the uptake of Ni2+ by the renal cortex, and (b) diethylmaleate pretreatment failed to increase NiCl2-induced cell injury further. Superoxide dismutase partially reduced the NiCl2-induced LDH release without affecting LPO and glutathione, whereas catalase did not affect such LDH release and LPO. Dimethylthiourea and DMSO completely prevented NiCl2-induced LPO, but only partially reduced LDH release. Deferoxamine prevented NiCl2-induced renal cell injury without affecting LPO and without significantly reducing Ni2+ uptake by the renal cortex, suggesting that nickel chelation is not important in such prevention of injury. NiCl2-induced inhibition of para-aminohippurate uptake was prevented significantly by thiols, deferoxamine, and dimethylthiourea. NiCl2-induced loss of cellular glutathione content was prevented significantly by thiols and deferoxamine, but not by superoxide dismutase and dimethylthiourea. These results suggest that LPO was not related to NiCl2-induced lethal renal cell injury, whereas such injury may be caused by the induction of the Fenton reaction, generating hydroxyl radicals.
We have recently cloned a gene, Cap43, that was significantly induced by exposure to nontoxic levels of both water-soluble and -insoluble Ni(2+) compounds. In this paper, we utilized the expression levels of this gene as a tool to identify second messengers involved in nickel-inducible transcription. We report here that the Ca(2+) ionophore A23187 substantially stimulated Cap43 gene expression. In addition, we found that BAPTA-AM, a specific chelator of free intracellular Ca(2+), consistently attenuated the induction of Cap43, indicating that elevation of intracellular Ca(2+) was essential for this response. TPEN, a chelator of heavy metals, such as Ni(2+) with a very low affinity for Ca(2+), did not attenuate Cap43 induced by Ni or calcium ionophore, suggesting that elevations of Ca(2+) but probably not elevations of other metal ions were involved in the induction of Cap43. A direct measurement of Ca(2+) levels using the fluorescent probe Fluo-3 AM showed elevations of free intracellular Ca(2+) in Ni-treated cells. A strong induction of Cap43 by okadaic acid suggested the involvement of a serine/threonine phosphorylation in a signaling pathway that was presumably activated by Ni and that led to enhanced Cap43 gene expression. However, calcium-dependent protein kinase(s) involved in the nickel-activated signaling pathway remains to be identified.
Isolated rat lymphocytes in salts-glucose medium (pH 7.2) were incubated with nickel chloride, nickel acetate, nickel sulfate, and a soluble form of nickel subsulfide (0-2 mM) at 37 degrees C for 2 h. The soluble form of nickel subsulfide induced a significant increase in DNA-protein crosslinks (DPXLs) (111%) beginning at 0.5 mM and a maximum increase of 700% from that of the control value was reached at a 2 mM concentration, whereas nickel sulfate produced only a 65% increase of such crosslinks at the 2 mM concentration only. No significant reduction in viability of rat lymphocytes (as measured by trypan blue exclusion) due to these nickel compounds was observed at any concentration used. Time-course studies of DPXLs and cellular viability due to 2 mM nickel subsulfide indicate that DPXL formation may not be due in part to cellular necrosis. Coincubation of nickel subsulfide (2 mM) with l-histidine (16 mM), l-cysteine (4 or 8 mM), or l-aspartic acid (24 mM) significantly reduced the DPXLs induced by 2 mM nickel subsulfide. But Mg(2+) even at 24 mM failed to antagonize nickel subsulfide-induced increase in DPXLs. High concentrations of these amino acids significantly decreased the accumulation of Ni(2+) from nickel subsulfide in lymphocytes, suggesting that such reduction of cellular uptake of Ni(2+) by these amino acids is partly responsible for the potent protective effects of these amino acids against such genotoxicity of nickel subsulfide. In vitro exposure of lymphocytes to nickel subsulfide (0-2 mM) increased the formation of reactive oxygen species (ROS) in a concentration-dependent manner. Furthermore, coincubation of 2 mM nickel subsulfide with catalase, dimethylthiourea, mannitol, or vitamin C at 37 degrees C for 2 h resulted in a significant decrease of nickel subsulfide-induced formation of DPXLs, suggesting that nickel subsulfide-induced DPXLs formation in isolated rat lymphocytes is caused by the formation of ROS. The amino acid treatment also abrogated Ni(3)S(2)-induced generation of ROS. Deferoxamine (a highly specific iron chelator) treatment prevented nickel subsulfide-induced DNA-protein crosslink formation, suggesting that Ni(2+)-induced DPXL formation in rat lymphocytes is caused by the induction of Fenton/Haber-Weiss reaction, generating hydroxyl radicals. The potent protective effects of these specific amino acids against nickel subsulfide-induced DPXL formation in isolated rat lymphocytes may be due in part to impaired cellular uptake of Ni(2+), inhibition of the binding of Ni(2+) to deproteinized DNA, and a reduction in reactive oxygen species.
Cytotoxicity of nickel compounds was studied by stimulating the repair synthesis of DNA and counting lymphocyte micronuclei in workers of smelting shop of copper-nickel sulfide processing plant. Nickel content in the organism was evaluated by its concentrations in hair. Therapy with ascorbic acid (1 g/day for 1 month) led to a significant decrease in the number of micronuclei. The number of micronuclei before and after ascorbic acid treatment varied within a wide range in different individuals.
Using the comet assay, we showed that nickel chloride at 250-1000 microM induced DNA damage in human lymphocytes, measured as the change in comet tail moment, which increased with nickel concentration up to 500 microM and then decreased. Observed increase might follow from the induction of strand breaks or/and alkali-labile sites (ALS) by nickel, whereas decrease from its induction of DNA-DNA and/or DNA-protein cross-links. Proteinase K caused an increase in the tail moment, suggesting that nickel chloride at 1000 microM might cross-link DNA with nuclear proteins. Lymphocytes exposed to NiCl(2) and treated with enzymes recognizing oxidized and alkylated bases: endonuclease III (Endo III), formamidopyrimidine-DNA glycosylase (Fpg) and 3-methyladenine-DNA glycosylase II (AlkA), displayed greater extent of DNA damage than those not treated with these enzymes, indicating the induction of oxidized and alkylated bases by nickel. The incubation of lymphocytes with spin traps, 5,5-dimethyl-pyrroline N-oxide (DMPO) and PBN decreased the extent of DNA damage, which might follow from the production of free radicals by nickel. The pre-treatment with Vitamin C at 10 microM and Vitamin E at 25 microM decreased the tail moment of the cells exposed to NiCl(2) at the concentrations of the metal causing strand breaks or/and ALS. The results obtained suggest that free radicals may be involved in the formation of strand breaks or/and ALS in DNA as well as DNA-protein cross-links induced by NiCl(2). Nickel chloride can also alkylate DNA bases. Our results support thesis on multiple, free radicals-based genotoxicity pathways of nickel.
To understand the different implication of various forms of DNA damage in genotoxicity of nickel and cadmium.
Human peripheral lymphocyte was exposed to nickel chloride and cadmium chloride in vitro. Levels of DNA single-and double-strand breaks and DNA-protein crosslinks in human peripheral lymphocyte were determined with single cell gel electrophoresis (SCGE). Activity of poly (ADP-ribose) polymerase (PARP) was determined by [(3)H]-NAD incorporating method.
Levels of DNA single-and double-strand breaks and DNA-protein crosslinks in human peripheral lymphocyte treated with nickel and cadmium were significantly higher than those untreated, but dose-response relationship only showed in those treated with 0.10 - 10.00 micromol/L of nickel chloride and 0.16 - 20.00 micromol/L of cadmium. Low levels of the two kinds of metal (0.10 - 0.40 micromol/L of nickel and 0.16 micromol/L of cadmium) could induce the cleavage of DNA and activate PARP, and high levels of the two kinds of metal (2.00 - 10.00 micromol/L of nickel and 0.80 - 20.00 micromol/L of cadmium) could not induce the enzyme cleavage of DNA.
Formation and cleavage of DNA double strand and blockage of activation of PARP can play an important role in carcinogenesis and mutagenesis.
Humans are exposed to carcinogenic nickel (Ni) compounds both occupationally and environmentally. In this paper, molecular mechanisms of nickel carcinogenesis are considered from the point-of-view of the uptake of nickel sulfide particles in cells, their dissolution and their effects on heterochromatin. Molecular mechanisms by which nickel induces gene silencing, DNA hypermethylation and inhibition of histone acetylation, will be discussed.
The effect of Cd(2+) on intracellular Ca(2+) homeostasis was examined in renal epithelial A6 cells loaded with Fura-2. Cd(2+) (10 microM to 1 mM) produced a transient spike in cytosolic Ca(2+) in a dose-dependent manner. The phospholipase C inhibitor U73122 and the cation receptor agonist, neomycin, both diminish Cd(2+)-evoked increase in intracellular Ca(2+) ([deltaCa(2+)](Cd)). Further, thapsigargin, an inhibitor of intracellular Ca(2+)-ATPases, significantly reduced [deltaCa(2+)](Cd). Extending these observations, inositol-3-phosphate (IP(3)) binding studies showed that the resting level of intracellular IP(3) underwent a 1.45-fold increase when exposed to Cd(2+). Furthermore, we found that the Cd(2+)-related heavy metals, Zn(2+) and Ni(2+), were even more potent inducers of Ca(2+) mobilization and IP(3) generation than Cd(2+). It can be concluded that Cd(2+), and possibly Zn(2+) and Ni(2+), may act as agonists of a cation-sensing receptor (CSR) belonging to G-protein receptors capable of mediating IP(3) release of Ca(2+) from intracellular stores. The CSR receptor in A6 epithelia could not be stimulated with neomycin or Gd(3+), suggesting that the receptor is different from the calcium-sensing receptor.
In order to elucidate the oxidative effects and genotoxicity of nickel on human lymphocytes in vitro, we report the level of intracellular reactive oxygen species (ROS), lipid peroxidation, hydroxyl radical ((*)OH), and DNA damage in human lymphocytes after acute exposure to inorganic nickel. NiCl(2) appeared to increase the formation of the fluorescent oxidized compound dichlorofluorescein (DCF). Lipid peroxidation in lymphocytes significantly increased compared to control. 2,3- and 2,5-DHB increased markedly in a concentration-dependent manner. Single-strand DNA breakage induced by Ni in lymphocytes was evaluated by Comet assay. Significant increase in DNA damage score (arbitrary units) showed a dose-related elevation after treatment with NiCl(2). NiCl(2) induced lipid peroxidation at 0.5 mM but had no effect on DNA strand breakage. These results support the emerging concept that NiCl(2)-induced oxidative stress and genotoxicity may be caused by oxygen radical intermediates. NiCl(2)-induced DNA strand breakage is related to the generation of the (*)OH radical.
It has been suggested that Nickel is involved in oxidative damage and inhibition of DNA repair. We studied the effects of NiSO4 on oxidative stress and DNA repair in Jurkat cells to elucidate its mechanism of action. Cells were treated with H2O2 and ROS generation (by flow cytometry), and oxidative DNA damage (as tail moment by Fpg-enzyme comet test), were evaluated immediately and after 4 and 24 h of DNA damage recovery occurred in presence or absence of NiSO4 (0.017 and 0.17 microM) to clarify possible interactions of Ni with DNA repair processes. Moreover, cells were exposed to the same doses of NiSO4 for 4 and 24 hours to evaluate its direct oxidative effect. The results of the comet test showed high tail moment immediately after oxidative burst with a decreasing after 4 h of DNA recovery, and a slight increase after 24 h of recovery. The decreases were more limited for cells treated with NiSO4 0.17 microM indicating an inhibition of oxidative DNA damage repair by this substance. An induction of ROS was observed after 4 h of incubation with higher dose of NiSO4. Cells treated with H2O2 showed the highest level of ROS after 4 h of recovery in presence of NiSO4 0.17 microM that remained at elevated levels also after 24 h of recovery suggesting a synergistic action of Ni with H2O2 in the reduction of cellular anti-oxidative defence activities.
Human exposure to highly nickel-polluted environments, such as those associated with nickel refining, electroplating, and welding, has the potential to produce a variety of pathologic effects. Among them are skin allergies, lung fibrosis, and cancer of the respiratory tract. The exact mechanisms of nickel-induced carcinogenesis are not known and have been the subject of numerous epidemiologic and experimental investigations. These mechanisms are likely to involve genetic and epigenetic routes. The present review provides evidence for the genotoxic and mutagenic activity of Ni(II) particularly at high doses. Such doses are best delivered into the cells by phagocytosis of sparingly soluble nickel-containing dust particles. Ni(II) genotoxicity may be aggravated through the generation of DNA-damaging reactive oxygen species (ROS) and the inhibition of DNA repair by this metal. Broad spectrum of epigenetic effects of nickel includes alteration in gene expression resulting from DNA hypermethylation and histone hypoacetylation, as well as activation or silencing of certain genes and transcription factors, especially those involved in cellular response to hypoxia. The investigations of the pathogenic effects of nickel greatly benefit from the understanding of the chemical basis of Ni(II) interactions with intracellular targets/ligands and oxidants. Many pathogenic effects of nickel are due to the interference with the metabolism of essential metals such as Fe(II), Mn(II), Ca(II), Zn(II), or Mg(II). Research in this field allows for identification of putative Ni(II) targets relevant to carcinogenesis and prediction of pathogenic effects caused by exposure to nickel. Ultimately, the investigations of nickel carcinogenesis should be aimed at the development of treatments that would inhibit or prevent Ni(II) interactions with critical target molecules and ions, Fe(II) in particular, and thus avert the respiratory tract cancer and other adverse health effects in nickel workers.