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Meaza I, Williams AR, Lu H, Kouokam JC, Toyoda JH, Croom-Perez TJ, Wise SS, Aboueissa AEM, Wise JP. Prolonged particulate hexavalent chromium exposure induces RAD51 foci inhibition and cytoplasmic accumulation in immortalized and primary human lung bronchial epithelial cells. Toxicol Appl Pharmacol 2023; 479:116711. [PMID: 37805091 PMCID: PMC10841504 DOI: 10.1016/j.taap.2023.116711] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/04/2023] [Accepted: 10/04/2023] [Indexed: 10/09/2023]
Abstract
Hexavalent chromium [Cr(VI)] is a human lung carcinogen with widespread exposure risks. Cr(VI) causes DNA double strand breaks that if unrepaired, progress into chromosomal instability (CIN), a key driving outcome in Cr(VI)-induced tumors. The ability of Cr(VI) to cause DNA breaks and inhibit repair is poorly understood in human lung epithelial cells, which are extremely relevant since pathology data show Cr(VI)-induced tumors originate from bronchial epithelial cells. In the present study, we considered immortalized and primary human bronchial epithelial cells. Cells were treated with zinc chromate at concentrations ranging 0.05 to 0.4μg/cm2 for acute (24 h) and prolonged (120 h) exposures. DNA double strand breaks (DSBs) were measured by neutral comet assay and the status of homologous recombination repair, the main pathway to fix Cr(VI)-induced DSBs, was measured by RAD51 foci formation with immunofluorescence, RAD51 localization with confocal microscopy and sister chromatid exchanges. We found acute and prolonged Cr(VI) exposure induced DSBs. Acute exposure induced homologous recombination repair, but prolonged exposure inhibited it resulting in chromosome instability in immortalized and primary human bronchial epithelial cells.
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Affiliation(s)
- Idoia Meaza
- Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville, 500 S Preston Street, Building 55A, Room 1422, Louisville, KY 40292, United States of America
| | - Aggie R Williams
- Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville, 500 S Preston Street, Building 55A, Room 1422, Louisville, KY 40292, United States of America
| | - Haiyan Lu
- Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville, 500 S Preston Street, Building 55A, Room 1422, Louisville, KY 40292, United States of America
| | - J Calvin Kouokam
- Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville, 500 S Preston Street, Building 55A, Room 1422, Louisville, KY 40292, United States of America
| | - Jennifer H Toyoda
- Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville, 500 S Preston Street, Building 55A, Room 1422, Louisville, KY 40292, United States of America
| | - Tayler J Croom-Perez
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, 6900 Lake Nona Blvd., Orlando, FL 32827, United States of America
| | - Sandra S Wise
- Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville, 500 S Preston Street, Building 55A, Room 1422, Louisville, KY 40292, United States of America
| | | | - John Pierce Wise
- Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville, 500 S Preston Street, Building 55A, Room 1422, Louisville, KY 40292, United States of America.
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Valiente S, Krawic C, Zhitkovich A. ATR activation by Cr-DNA damage is a major survival response establishing late S and G2 checkpoints after Cr(VI) exposure. Toxicol Appl Pharmacol 2023; 477:116696. [PMID: 37734571 PMCID: PMC10591798 DOI: 10.1016/j.taap.2023.116696] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/17/2023] [Accepted: 09/18/2023] [Indexed: 09/23/2023]
Abstract
Inhalation exposure to hexavalent chromium is known to cause lung cancer and other pulmonary toxicity. Cellular metabolism of chromium(VI) entering cells as chromate anion produces different amounts of reactive Cr(V) intermediates and finally yields Cr(III). Direct reduction of Cr(VI) by ascorbate (Asc), the dominant metabolic reaction in vivo but not in standard cell cultures, skips production of Cr(V) but still permits extensive formation of Cr-DNA damage. To understand the importance of different forms of biological injury in Cr(VI) toxicity, we examined activation of several protein- and DNA damage-sensitive stress responses in human lung cells under Asc-restored conditions. We found that Asc-restored cells suppressed upregulation of oxidant-sensitive stress systems by Cr(VI) but showed a strong activation of the apical DNA damage-responsive kinase ATR. ATR signaling was triggered in late S phase and persisted upon entry of cells into G2 phase. Inhibition of ATR prevented the establishment of late-S and G2 cell cycle checkpoints and did not lead to a compensatory activation of a related kinase ATM. Inactivation of ATR also strongly impaired viability of Cr(VI)-treated lung cells including stem-like cells and revealed a significant formation of toxic Cr-DNA damage at low Cr(VI) doses. Our findings identified a major Cr(VI) resistance mechanism involving sensing of Cr-DNA damage by ATR in late S phase and a subsequent establishment of protective cell cycle checkpoints.
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Affiliation(s)
- Sophia Valiente
- Brown University, Legorreta Cancer Center, Department of Pathology and Laboratory Medicine, Providence, RI 02912, USA
| | - Casey Krawic
- Brown University, Legorreta Cancer Center, Department of Pathology and Laboratory Medicine, Providence, RI 02912, USA
| | - Anatoly Zhitkovich
- Brown University, Legorreta Cancer Center, Department of Pathology and Laboratory Medicine, Providence, RI 02912, USA.
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Phosphate Buffer Solubility and Oxidative Potential of Single Metals or Multielement Particles of Welding Fumes. ATMOSPHERE 2020. [DOI: 10.3390/atmos12010030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
To evaluate the chemical behavior and the health impact of welding fumes (WF), a complex and heterogeneous mixture of particulate metal oxides, two certified reference materials (CRMs) were tested: mild steel WF (MSWF-1) and stainless steel WF (SSWF-1). We determined their total chemical composition, their solubility, and their oxidative potential in a phosphate buffer (PB) solution under physiological conditions (pH 7.4 and 37 °C). The oxidative potential (OPDTT) of WF CRMs was evaluated using an acellular method by following the dithiothreitol (DTT) consumption rate (µmol DTT L−1 min−1). Pure metal salts present in the PB soluble fraction of the WF CRMs were tested individually at equivalent molarity to estimate their specific contribution to the total OPDTT. The metal composition of MSWF-1 consisted mainly of Fe, Zn, Mn, and Cu and the SSWF-1 composition consisted mainly of Fe, Mn, Cr, Ni, Cu, and Zn, in diminishing order. The metal PB solubility decreased from Cu (11%) to Fe (approximately 0.2%) for MSWF-1 and from Mn (9%) to Fe (<1%) for SSWF-1. The total OPDTT of SSWF-1 is 2.2 times the OPDTT of MSWF-1 due to the difference in oxidative capacity of soluble transition metals. Cu (II) and Mn (II) are the most sensitive towards DTT while Cr (VI), Fe (III), and Zn (II) are barely reactive, even at higher concentrations. The OPDTT measured for both WF CRMs extracts compare well with simulated extracts containing the main metals at their respective PB-soluble concentrations. The most soluble transition metals in the simulated extract, Mn (II) and Cu (II), were the main contributors to OPDTT in WF CRMs extracts. Mn (II), Cu (II), and Ni (II) might enhance the DTT oxidation by a redox catalytic reaction. However, summing the main individual soluble metal DTT response induces a large overestimation probably linked to modifications in the speciation of various metals when mixed. The complexation of metals with different ligands present in solution and the interaction between metals in the PB-soluble fraction are important phenomena that can influence OPDTT depletion and therefore the potential health effect of inhaled WF.
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Abstract
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Vitamin
C (ascorbic acid) is a water-soluble antioxidant and a
cofactor for a large number of enzymes. It is present in all tissues
and especially abundant in corneal epithelium, stem cells, and neurons.
Although similar to thiols in its ability to react with many reactive
oxygen species (ROS), ascorbate is much better (>100× faster)
than glutathione at scavenging of primary ROS (superoxide radical
and singlet oxygen). Ascorbate appears to be especially important
for elimination of O2•– in the
nucleus which contains little or no SOD activity. Cofactor functions
of ascorbate involve the maintenance of activity of Fe(II)/2-oxoglutarate-dependent
dioxygenases via reduction of Fe(III). The most prominent activity
of ascorbate-dependent dioxygenases in the cytoplasm is hydroxylation
of prolines in proteins involved in the formation of extracellular
matrix and regulation of metabolism and hypoxia responses. In the
nucleus, ascorbate is important for oxidative demethylation of 5-methylcytosine
in DNA (by TET proteins) and removal of methyl groups from histone
lysines (by JmjC demethylases). Differentiation and other cellular
reprograming processes involving DNA demethylation are especially
sensitive to ascorbate insufficiency. High doses of vitamin C alone
or in combinations with drugs produced cancer-suppressive effects
which involved redox, immune, and epigenetic mechanisms. Solutions
to vitamin C deficiency in cultured cells are discussed to improve
the physiological relevance of in vitro models. An
abundance of vitamin C in rodents limits their ability to fully recapitulate
human sensitivity to adverse health effects of malnutrition and xenobiotics,
including neurotoxicity, lung injury, and intergenerational and other
epigenetic effects.
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Affiliation(s)
- Anatoly Zhitkovich
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Providence, Rhode Island 02912, United States
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Zhang S, Zhang J, Cheng W, Chen H, Wang A, Liu Y, Hou H, Hu Q. Combined cell death of co-exposure to aldehyde mixtures on human bronchial epithelial BEAS-2B cells: Molecular insights into the joint action. CHEMOSPHERE 2020; 244:125482. [PMID: 31812766 DOI: 10.1016/j.chemosphere.2019.125482] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 11/08/2019] [Accepted: 11/26/2019] [Indexed: 06/10/2023]
Abstract
Aldehydes are common air pollutants and metabolites of the organism, which widely exist in many in vivo (e.g. Alzheimer's disease) and in vitro (e.g. cigarette smoke) situations. Individual aldehydes have been studied well alone, while their combined toxicity is still obscure. Here, we examined the combined apoptosis of aldehyde mixtures in BEAS-2B cells at smoking-related environmental/physiologically relevant concentrations, and the potential mechanism was investigated further based on the related signaling pathway. Co-exposure to aldehyde mixtures demonstrated significant synergistic interaction on apoptosis in a concentration-dependent manner, which differed from the expectation based on single aldehydes. Moreover, formaldehyde significantly potentiated the induction of death receptor-5, caspase 8/10, cleaved caspase 3/7/9, pro-apoptotic proteins (Bim, Bad and Bax), depolarization of MMP (mitochondrial membrane potential) and AIF (apoptosis-inducing factor) induced by acrolein, and synergistically decreased expressions of pro-survival proteins (Bcl-2 and Bcl-XL) and poly ADP-ribose polymerase. Therefore, aldehyde mixture-induced synergistic apoptosis was mediated both by TRAIL death receptor and mitochondrial pathway. Additionally, reactive oxygen species, Ca2+ levels, DNA damage, and phosphorylated MDM2 were all synergistically induced by aldehyde mixtures, while total p53, phosphorylated p53 and phosphorylated AKT (serine/threonine kinase) were inhibited. Antioxidants N-acetylcysteine suppressed the aldehyde mixture-induced ROS, DNA damage and apoptosis, and blocked the TRAIL death receptor and mitochondrial pathway, while it did not rescue the p53 and AKT pathway. Briefly, aldehyde mixtures induced synergistic apoptosis even at smoking-related environmental/physiologically relevant concentrations, which could be enhanced through ROS-mediated death receptor/mitochondrial pathway, and the down-regulation of phosphorylated AKT.
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Affiliation(s)
- Sen Zhang
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China; Institute of Applied Technology, Hefei Institute of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China; University of Science and Technology of China, Hefei, 230026, PR China
| | - Jingni Zhang
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China; Institute of Applied Technology, Hefei Institute of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China; University of Science and Technology of China, Hefei, 230026, PR China
| | - Wanyan Cheng
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China; Institute of Applied Technology, Hefei Institute of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China
| | - Huan Chen
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China
| | - An Wang
- Institute of Applied Technology, Hefei Institute of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China
| | - Yong Liu
- Institute of Applied Technology, Hefei Institute of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China
| | - Hongwei Hou
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China.
| | - Qingyuan Hu
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China.
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Zhang S, Zhang J, Chen H, Wang A, Liu Y, Hou H, Hu Q. Combined cytotoxicity of co-exposure to aldehyde mixtures on human bronchial epithelial BEAS-2B cells. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 250:650-661. [PMID: 31035147 DOI: 10.1016/j.envpol.2019.03.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/25/2019] [Accepted: 03/28/2019] [Indexed: 06/09/2023]
Abstract
Aldehydes are well-known air pollutants and often studied alone, while co-exposure to aldehyde mixtures is more common than single aldehydes. Unfortunately, it has been very little known about the (mechanism of) combined toxicity of aldehyde mixtures. Here, formaldehyde and acrolein were selected as the typical representatives of common aldehydes, and were used to explore to get in-depth insight into the mechanism of combined toxicity of aldehyde mixtures. The NOECs (non-observed effect concentrations) are 60 μmoL/L for formaldehyde, and 0.5 μmoL/L for acrolein, so acrolein is more toxic than formaldehyde. Formaldehyde and acrolein mixtures showed significant cytotoxicity and synergistic effects in a concentration/time-dependent way on BEAS-2B cells based on acute and chronic cytotoxicity assay. Acrolein was dominant in aldehyde mixtures in inducing cytotoxicity at environmentally relevant doses because of higher toxicity. Moreover, aldehyde mixtures significantly synergistically increased the intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and lactate dehydrogenase (LDH) leakage, while caused an antagonistic effects on glutathione (GSH). Besides, formaldehyde could significantly potentiated the activation of environmental stress sensitive Nrf2 pathway induced by acrolein, even at doses at which formaldehyde treatment alone had no any response. Furthermore, as the downstream components of Nrf2 pathway, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX) and heme oxygenase-1 (HO-1) were significantly synergistically induced by formaldehyde and acrolein mixtures. Antioxidants N-acetylcysteine and reduced glutathione could significantly suppress the acute and chronic combined cytotoxicity of acrolein and formaldehyde mixtures, and changed their interactions (synergism) on cytotoxicity. Taken together, aldehyde mixtures have higher toxicity than that expected for additivity based on single aldehydes even at environmentally relevant concentrations, and the combined cytotoxicity may be enhanced through oxidative stress and the related Nrf2 pathway. Prolonged exposure to pollutants containing aldehyde mixtures through inhalation may have more serious threat to respiratory system in animal and human.
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Affiliation(s)
- Sen Zhang
- Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China; University of Science and Technology of China, Hefei, 230026, PR China; China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China
| | - Jingni Zhang
- Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China; University of Science and Technology of China, Hefei, 230026, PR China; China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China
| | - Huan Chen
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China
| | - An Wang
- Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China
| | - Yong Liu
- Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China
| | - Hongwei Hou
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China.
| | - Qingyuan Hu
- China National Tobacco Quality Supervision & Test Center, Zhengzhou, 450001, PR China
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Rubis B, Luczak MW, Krawic C, Zhitkovich A. Vitamin C increases DNA breaks and suppresses DNA damage-independent activation of ATM by bleomycin. Free Radic Biol Med 2019; 136:12-21. [PMID: 30926564 PMCID: PMC6488359 DOI: 10.1016/j.freeradbiomed.2019.03.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/25/2019] [Accepted: 03/25/2019] [Indexed: 01/07/2023]
Abstract
Bleomycin is a redox-active drug with anticancer and other clinical applications. It is also frequently used as a tool in fundamental research on cellular responses to DNA double-strand breaks (DSBs). A conversion of bleomycin into its DNA-breaking form requires Fe, one-electron donors and O2. Here, we examined how a major biological antioxidant ascorbate (reduced vitamin C), which is practically absent in standard cell culture, impacts cellular responses to bleomycin. We found that restoration of physiological levels of vitamin C in human cancer cells increased their killing by bleomycin in 2D cultures and 3D tumor spheroids. Higher cytotoxicity of bleomycin occurred in cells with normal and shRNA-depleted p53. Cellular vitamin C enhanced the ability of bleomycin by produce DSBs, which was established by direct measurements of these lesions in three cell lines. Vitamin C-restored cancer cells also showed a higher sensitivity to killing by low-dose bleomycin in combination with inhibitors of DSB repair-activating ATM or DNA-PK kinases. The presence of ascorbate in bleomycin-treated cells suppressed a DSB-independent activation of the ATM-CHK2 axis by blocking superoxide radical. In vitro studies detected a greatly superior ability of ascorbate over other cellular reducers to catalyze DSB formation by bleomycin. Ascorbate was faster than other antioxidants in promoting two steps in activation of bleomycin. Our results demonstrate strong activation effects of vitamin C on bleomycin, shifting its toxicity further toward DNA damage and making it more sensitive to manipulations of DNA repair.
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Affiliation(s)
- Blazej Rubis
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Providence, RI, 02912, USA
| | - Michal W Luczak
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Providence, RI, 02912, USA
| | - Casey Krawic
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Providence, RI, 02912, USA
| | - Anatoly Zhitkovich
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Providence, RI, 02912, USA.
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