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Pan C, Liu HD, Gong Z, Yu X, Hou XB, Xie DD, Zhu XB, Li HW, Tang JY, Xu YF, Yu JQ, Zhang LY, Fang H, Xiao KH, Chen YG, Wang JY, Pang Q, Chen W, Sun JP. Cadmium is a potent inhibitor of PPM phosphatases and targets the M1 binding site. Sci Rep 2014; 3:2333. [PMID: 23903585 PMCID: PMC3730172 DOI: 10.1038/srep02333] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 06/24/2013] [Indexed: 11/16/2022] Open
Abstract
The heavy metal cadmium is a non-degradable pollutant. By screening the effects of a panel of metal ions on the phosphatase activity, we unexpectedly identified cadmium as a potent inhibitor of PPM1A and PPM1G. In contrast, low micromolar concentrations of cadmium did not inhibit PP1 or tyrosine phosphatases. Kinetic studies revealed that cadmium inhibits PPM phosphatases through the M1 metal ion binding site. In particular, the negative charged D441 in PPM1G specific recognized cadmium. Our results suggest that cadmium is likely a potent inhibitor of most PPM family members except for PHLPPs. Furthermore, we demonstrated that cadmium inhibits PPM1A-regulated MAPK signaling and PPM1G-regulated AKT signaling potently in vivo. Cadmium reversed PPM1A-induced cell cycle arrest and cadmium insensitive PPM1A mutant rescued cadmium induced cell death. Taken together, these findings provide a better understanding of the effects of the toxicity of cadmium in the contexts of human physiology and pathology.
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Affiliation(s)
- Chang Pan
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University, School of Medicine, Jinan, Shandong 250012, China
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Gao D, Xu Z, Zhang X, Zhu C, Wang Y, Min W. Cadmium triggers kidney cell apoptosis of purse red common carp (Cyprinus carpio) without caspase-8 activation. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2013; 41:728-737. [PMID: 23954723 DOI: 10.1016/j.dci.2013.08.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/31/2013] [Accepted: 08/02/2013] [Indexed: 06/02/2023]
Abstract
Caspase-8, the essential initiator caspase, is believed to play a pivotal role in death receptor-mediated apoptotic pathway. It also participates in mitochondria-mediated apoptosis via cleavage of proapoptotic Bid in mammals. However, its role in fish remains elusive in Cadmium-induced apoptotic pathway. In this study, we isolated the caspase-8 gene from common carp, one of the most important industrial aquatic animals in China using rapid amplification of cDNA ends (RACE). The deduced amino acid sequence of caspase-8 comprised 475 amino acids, which showed approximately 64.1% identity and 79.8% similarity to zebrafish (Danio rerio) caspase-8, possessed two conserved death effector domains, a large subunit and a small subunit. Phylogenetic analysis demonstrated that caspase-8 formed a clade with zebrafish caspase-8. In kidney, cadmium (Cd) exposure triggered apoptosis and increased caspase-3 and -9 activities, whereas it did not affect caspase-8 activity. Real-time quantitative PCR analysis revealed that caspase-8 transcriptional level was not significantly increased in kidney after exposure to Cd. Using Western blot analysis, no caspase-8 cleaved fragment was detected and no significant alteration of procaspase-8 level was found with the same Cd-treated condition. Moreover, the immunopositive staining was predominantly limited to the cytoplasm of renal tubular epithelial cells and no remarkable changes of immunoreactivities were observed using immunohistochemical detection after Cd treatment. The results reveal that Cd can trigger apoptosis, while it cannot activate caspase-8 in purse red common carp.
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Affiliation(s)
- Dian Gao
- Medical College of Nanchang University, Nanchang 330006, PR China; Institute of Immunotherapy, Nanchang University, Nanchang 330006, PR China
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Zhu WJ, Li M, Liu C, Qu JP, Min YH, Xu SW, Li S. Avermectin induced liver injury in pigeon: mechanisms of apoptosis and oxidative stress. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2013; 98:74-81. [PMID: 24138898 DOI: 10.1016/j.ecoenv.2013.09.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Revised: 09/08/2013] [Accepted: 09/12/2013] [Indexed: 06/02/2023]
Abstract
Extensive use of avermectin (AVM) can result in environment pollution, and it is important to evaluate the potential impact this antibiotic has on ecological systems. Few published literatures have discussed the liver injury mechanisms induced by AVM on birds. In this study, pigeons were exposed to feed containing AVM (0, 20, 40 and 60 mg/kg diet) for 30, 60, 90 days respectively. The results showed that AVM increased the number of apoptosis and the expression level of caspase-3, 8, fas mRNA in the liver of pigeons. Ultrastructural alterations, including mitochondrial damage and chromatin aggregation, become severe with increase exposure dose. Exposure to AVM induced significant changes in antioxidant enzyme {superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px)} activities and malondialdehyde (MDA) content, augmented protein carbonyl (PCO) content and DNA-protein crosslink (DPC) coefficient, in a concentration-dependent manner in the liver of pigeons. Our results show that AVM has toxic effect in pigeon liver, and the mechanism of injury caused by AVM is closely related to apoptosis and oxidative stress.
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Affiliation(s)
- Wen-Jun Zhu
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
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Son YO, Pratheeshkumar P, Lei W, Wang X, Kim DH, Lee JY, Zhang Z, Lee JC, Shi X. Reactive oxygen species mediate Cr(VI)-induced carcinogenesis through PI3K/AKT-dependent activation of GSK-3β/β-catenin signaling. Toxicol Appl Pharmacol 2013; 271:239-48. [PMID: 23707771 PMCID: PMC3742697 DOI: 10.1016/j.taap.2013.04.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 04/19/2013] [Accepted: 04/20/2013] [Indexed: 01/07/2023]
Abstract
Cr(VI) compounds are known human carcinogens that primarily target the lungs. Cr(VI) produces reactive oxygen species (ROS), but the exact effects of ROS on the signaling molecules involved in Cr(VI)-induced carcinogenesis have not been extensively studied. Chronic exposure of human bronchial epithelial cells to Cr(VI) at nanomolar concentrations (10-100nM) for 3months not only induced cell transformation, but also increased the potential of these cells to invade and migrate. Injection of Cr(VI)-stimulated cells into nude mice resulted in the formation of tumors. Chronic exposure to Cr(VI) increased levels of intracellular ROS and antiapoptotic proteins. Transfection with catalase or superoxide dismutase (SOD) prevented Cr(VI)-mediated increases in colony formation, cell invasion, migration, and xenograft tumors. While chronic Cr(VI) exposure led to activation of signaling cascades involving PI3K/AKT/GSK-3β/β-catenin and PI3K/AKT/mTOR, transfection with catalase or SOD markedly inhibited Cr(VI)-mediated activation of these signaling proteins. Inhibitors specific for AKT or β-catenin almost completely suppressed the Cr(VI)-mediated increase in total and active β-catenin proteins and colony formation. In particular, Cr(VI) suppressed autophagy of epithelial cells under nutrition deprivation. Furthermore, there was a marked induction of AKT, GSK-3β, β-catenin, mTOR, and carcinogenic markers in tumor tissues formed in mice after injection with Cr(VI)-stimulated cells. Collectively, our findings suggest that ROS is a key mediator of Cr(VI)-induced carcinogenesis through the activation of PI3K/AKT-dependent GSK-3β/β-catenin signaling and the promotion of cell survival mechanisms via the inhibition of apoptosis and autophagy.
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Affiliation(s)
- Young-Ok Son
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
| | - Poyil Pratheeshkumar
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
| | - Wang Lei
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
| | - Xin Wang
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
| | - Dong-Hern Kim
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
| | - Ju-Yeon Lee
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
| | - Zhuo Zhang
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
| | - Jeong-Chae Lee
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
- School of Dentistry and Institute of Oral Biosciences, Research Center of Bioactive Materials, Chonbuk National University, Jeonju 561-756, South Korea
| | - Xianglin Shi
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
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Cadmium and cellular signaling cascades: interactions between cell death and survival pathways. Arch Toxicol 2013; 87:1743-86. [PMID: 23982889 DOI: 10.1007/s00204-013-1110-9] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Accepted: 07/29/2013] [Indexed: 12/20/2022]
Abstract
Cellular stress elicited by the toxic metal Cd(2+) does not coerce the cell into committing to die from the onset. Rather, detoxification and adaptive processes are triggered concurrently, allowing survival until normal function is restored. With high Cd(2+), death pathways predominate. However, if sublethal stress levels affect cells for prolonged periods, as in chronic low Cd(2+) exposure, adaptive and survival mechanisms may deregulate, such that tumorigenesis ensues. Hence, death and malignancy are the two ends of a continuum of cellular responses to Cd(2+), determined by magnitude and duration of Cd(2+) stress. Signaling cascades are the key factors affecting cellular reactions to Cd(2+). This review critically surveys recent literature to outline major features of death and survival signaling pathways as well as their activation, interactions and cross talk in cells exposed to Cd(2+). Under physiological conditions, receptor activation generates 2nd messengers, which are short-lived and act specifically on effectors through their spatial and temporal dynamics to transiently alter effector activity. Cd(2+) recruits physiological 2nd messenger systems, in particular Ca(2+) and reactive oxygen species (ROS), which control key Ca(2+)- and redox-sensitive molecular switches dictating cell function and fate. Severe ROS/Ca(2+) signals activate cell death effectors (ceramides, ASK1-JNK/p38, calpains, caspases) and/or cause irreversible damage to vital organelles, such as mitochondria and endoplasmic reticulum (ER), whereas low localized ROS/Ca(2+) levels act as 2nd messengers promoting cellular adaptation and survival through signal transduction (ERK1/2, PI3K/Akt-PKB) and transcriptional regulators (Ref1-Nrf2, NF-κB, Wnt, AP-1, bestrophin-3). Other cellular proteins and processes targeted by ROS/Ca(2+) (metallothioneins, Bcl-2 proteins, ubiquitin-proteasome system, ER stress-associated unfolded protein response, autophagy, cell cycle) can evoke death or survival. Hence, temporary or permanent disruptions of ROS/Ca(2+) induced by Cd(2+) play a crucial role in eliciting, modulating and linking downstream cell death and adaptive and survival signaling cascades.
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In vitro nasal epithelial toxicity by cadmium accompanies up-regulation of RUNX3 protein with activation of PI3-kinase/Akt. Mol Cell Toxicol 2013. [DOI: 10.1007/s13273-013-0020-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Yuan Y, Jiang CY, Xu H, Sun Y, Hu FF, Bian JC, Liu XZ, Gu JH, Liu ZP. Cadmium-induced apoptosis in primary rat cerebral cortical neurons culture is mediated by a calcium signaling pathway. PLoS One 2013; 8:e64330. [PMID: 23741317 PMCID: PMC3669330 DOI: 10.1371/journal.pone.0064330] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 04/11/2013] [Indexed: 11/20/2022] Open
Abstract
Cadmium (Cd) is an extremely toxic metal, capable of severely damaging several organs, including the brain. Studies have shown that Cd disrupts intracellular free calcium ([Ca2+]i) homeostasis, leading to apoptosis in a variety of cells including primary murine neurons. Calcium is a ubiquitous intracellular ion which acts as a signaling mediator in numerous cellular processes including cell proliferation, differentiation, and survival/death. However, little is known about the role of calcium signaling in Cd-induced apoptosis in neuronal cells. Thus we investigated the role of calcium signaling in Cd-induced apoptosis in primary rat cerebral cortical neurons. Consistent with known toxic properties of Cd, exposure of cerebral cortical neurons to Cd caused morphological changes indicative of apoptosis and cell death. It also induced elevation of [Ca2+]i and inhibition of Na+/K+-ATPase and Ca2+/Mg2+-ATPase activities. This Cd-induced elevation of [Ca2+]i was suppressed by an IP3R inhibitor, 2-APB, suggesting that ER-regulated Ca2+ is involved. In addition, we observed elevation of reactive oxygen species (ROS) levels, dysfunction of cytochrome oxidase subunits (COX-I/II/III), depletion of mitochondrial membrane potential (ΔΨm), and cleavage of caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP) during Cd exposure. Z-VAD-fmk, a pan caspase inhibitor, partially prevented Cd-induced apoptosis and cell death. Interestingly, apoptosis, cell death and these cellular events induced by Cd were blocked by BAPTA-AM, a specific intracellular Ca2+ chelator. Furthermore, western blot analysis revealed an up-regulated expression of Bcl-2 and down-regulated expression of Bax. However, these were not blocked by BAPTA-AM. Thus Cd toxicity is in part due to its disruption of intracellular Ca2+ homeostasis, by compromising ATPases activities and ER-regulated Ca2+, and this elevation in Ca2+ triggers the activation of the Ca2+-mitochondria apoptotic signaling pathway. This study clarifies the signaling events underlying Cd neurotoxicity, and suggests that regulation of Cd-disrupted [Ca2+]i homeostasis may be a new strategy for prevention of Cd-induced neurodegenerative diseases.
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Affiliation(s)
- Yan Yuan
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Chen-yang Jiang
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Hui Xu
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Ya Sun
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Fei-fei Hu
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Jian-chun Bian
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Xue-zhong Liu
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Jian-hong Gu
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
| | - Zong-ping Liu
- College of Veterinary Medicine, Yang Zhou University, Yangzhou, China
- * E-mail:
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Chang KC, Hsu CC, Liu SH, Su CC, Yen CC, Lee MJ, Chen KL, Ho TJ, Hung DZ, Wu CC, Lu TH, Su YC, Chen YW, Huang CF. Cadmium induces apoptosis in pancreatic β-cells through a mitochondria-dependent pathway: the role of oxidative stress-mediated c-Jun N-terminal kinase activation. PLoS One 2013; 8:e54374. [PMID: 23405080 PMCID: PMC3566170 DOI: 10.1371/journal.pone.0054374] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 12/11/2012] [Indexed: 11/19/2022] Open
Abstract
Cadmium (Cd), one of well-known highly toxic environmental and industrial pollutants, causes a number of adverse health effects and diseases in humans. The growing epidemiological studies have suggested a possible link between Cd exposure and diabetes mellitus (DM). However, the toxicological effects and underlying mechanisms of Cd-induced pancreatic β-cell injury are still unknown. In this study, we found that Cd significantly decreased cell viability, and increased sub-G1 hypodiploid cells and annexin V-Cy3 binding in pancreatic β-cell-derived RIN-m5F cells. Cd also increased intracellular reactive oxygen species (ROS) generation and malondialdehyde (MDA) production and induced mitochondrial dysfunction (the loss of mitochondrial membrane potential (MMP) and the increase of cytosolic cytochrome c release), the decreased Bcl-2 expression, increased p53 expression, poly (ADP-ribose) polymerase (PARP) cleavage, and caspase cascades, which accompanied with intracellular Cd accumulation. Pretreatment with the antioxidant N-acetylcysteine (NAC) effectively reversed these Cd-induced events. Furthermore, exposure to Cd induced the phosphorylations of c-jun N-terminal kinases (JNK), extracellular signal-regulated kinases (ERK)1/2, and p38-mitogen-activated protein kinase (MAPK), which was prevented by NAC. Additionally, the specific JNK inhibitor SP600125 or JNK-specific small interference RNA (si-RNA) transfection suppressed Cd-induced β-cell apoptosis and related signals, but not ERK1/2 and p38-MAPK inhibitors (PD98059 and SB203580) did not. However, the JNK inhibitor or JNK-specific si-RNA did not suppress ROS generation in Cd-treated cells. These results indicate that Cd induces pancreatic β-cell death via an oxidative stress downstream-mediated JNK activation-triggered mitochondria-regulated apoptotic pathway.
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Affiliation(s)
- Kai-Chih Chang
- Department of Physiology and Graduate Institute of Basic Medical Science, School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
| | - Ching-Cheng Hsu
- Department of Physiology and Graduate Institute of Basic Medical Science, School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
| | - Shing-Hwa Liu
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chin-Chuan Su
- Department of Otorhinolaryngology, Head and Neck Surgery, Changhua Christian Hospital, Changhua County, Taiwan
| | - Cheng-Chieh Yen
- Department of Occupational Safety and Health, College of Health Care and Management, Chung Shan Medical University, Taichung, Taiwan
- Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Ming-Jye Lee
- Department of Surgery, Peng-Hu Hospital, Makung City, Taiwan
- Department of Health, Executive Yuan, Taipei, Taiwan
| | - Kuo-Liang Chen
- Department of Urology, China Medical University Hospital, Taichung, Taiwan
| | - Tsung-Jung Ho
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Dong-Zong Hung
- Division of Toxicology, Trauma & Emergency Center, China Medical University Hospital, Taichung, Taiwan
| | - Chin-Ching Wu
- Department of Public Health, China Medical University, Taichung, Taiwan
| | - Tien-Hui Lu
- Department of Physiology and Graduate Institute of Basic Medical Science, School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
| | - Yi-Chang Su
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Ya-Wen Chen
- Department of Physiology and Graduate Institute of Basic Medical Science, School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
- * E-mail: (YWC); (CFH)
| | - Chun-Fa Huang
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan
- * E-mail: (YWC); (CFH)
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Son YO, Wang L, Poyil P, Budhraja A, Hitron JA, Zhang Z, Lee JC, Shi X. Cadmium induces carcinogenesis in BEAS-2B cells through ROS-dependent activation of PI3K/AKT/GSK-3β/β-catenin signaling. Toxicol Appl Pharmacol 2012; 264:153-60. [PMID: 22884995 PMCID: PMC3462234 DOI: 10.1016/j.taap.2012.07.028] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/21/2012] [Accepted: 07/28/2012] [Indexed: 01/31/2023]
Abstract
Cadmium has been widely used in industry and is known to be carcinogenic to humans. Although it is widely accepted that chronic exposure to cadmium increases the incidence of cancer, the mechanisms underlying cadmium-induced carcinogenesis are unclear. The main aim of this study was to investigate the role of reactive oxygen species (ROS) in cadmium-induced carcinogenesis and the signal transduction pathways involved. Chronic exposure of human bronchial epithelial BEAS-2B cells to cadmium induced cell transformation, as evidenced by anchorage-independent growth in soft agar and clonogenic assays. Chronic cadmium treatment also increased the potential of these cells to invade and migrate. Injection of cadmium-stimulated cells into nude mice resulted in the formation of tumors. In contrast, the cadmium-mediated increases in colony formation, cell invasion and migration were prevented by transfection with catalase, superoxide dismutase-1 (SOD1), or SOD2. In particular, chronic cadmium exposure led to activation of signaling cascades involving PI3K, AKT, GSK-3β, and β-catenin and transfection with each of the above antioxidant enzymes markedly inhibited cadmium-mediated activation of these signaling proteins. Inhibitors specific for AKT or β-catenin almost completely suppressed the cadmium-mediated increase in total and active β-catenin proteins and colony formation. Moreover, there was a marked induction of AKT, GSK-3β, β-catenin, and carcinogenic markers in tumor tissues formed in mice after injection with cadmium-stimulated cells. Collectively, our findings suggest a direct involvement of ROS in cadmium-induced carcinogenesis and implicate a role of AKT/GSK-3β/β-catenin signaling in this process.
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Affiliation(s)
- Young-Ok Son
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Lei Wang
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Pratheeshkumar Poyil
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Amit Budhraja
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - J. Andrew Hitron
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Zhuo Zhang
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Jeong-Chae Lee
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
- School of Dentistry and Institute of Oral Biosciences (BK21 program), Research Center of Bioactive Materials, Chonbuk National University, Jeonju 561-756, South Korea
| | - Xianglin Shi
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky
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Gogna R, Madan E, Keppler B, Pati U. Gallium compound GaQ(3) -induced Ca(2+) signalling triggers p53-dependent and -independent apoptosis in cancer cells. Br J Pharmacol 2012; 166:617-36. [PMID: 22074401 DOI: 10.1111/j.1476-5381.2011.01780.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE A novel anti-neoplastic gallium complex GaQ(3) (KP46), earlier developed by us, is currently in phase I clinical trial. GaQ(3) induced S-phase arrest and apoptosis via caspase/PARP cleavage in a variety of cancers. However, the underlying mechanism of apoptosis is unknown. Here, we have explored the mechanism(s) of GaQ(3) -induced apoptosis in cancer cells, focusing on p53 and intracellular Ca(2+) signalling. EXPERIMENTAL APPROACH GaQ(3) -induced cytotoxicity and apoptosis were determined in cancer cell lines, with different p53 status (p53(+/+) , p53(-/-) and p53 mutant). Time course analysis of intracellular Ca(2+) calcium release, p53 promoter activation, p53-nuclear/cytoplasmic movements and reactive oxygen species (ROS) were conducted. Ca(2+) -dependent formation of the p53-p300 transcriptional complex was analysed by co-immunoprecipitation and chromatin immunoprecipitation. Ca(2+) signalling, p53, p300 and ROS were serially knocked down to study Ca(2+) -p53-ROS ineractions in GaQ(3) -induced apoptosis. KEY RESULTS GaQ(3) triggered intracellular Ca(2+) release stabilizing p53-p300 complex and recruited p53 to p53 promoter, leading to p53 mRNA and protein synthesis. p53 induced higher intracellular Ca(2+) release and ROS followed by activation of p53 downstream genes including those for the micro RNA mir34a. In p53(-/-) and p53 mutant cells, GaQ(3) -induced Ca(2+) -signalling generated ROS. ROS further increased membrane translocation of FAS and FAS-mediated extrinsic apoptosis. CONCLUSIONS AND IMPLICATIONS This study disclosed a novel mechanism of Ca(2+) -signalling-mediated p53 activation and ROS up-regulation. Understanding the mechanism of GaQ(3) -induced apoptosis will help establish this gallium-based organic compound as a potent anti-cancer drug.
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Affiliation(s)
- Rajan Gogna
- Transcription and Human Biology Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
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Lee JC, Son YO, Pratheeshkumar P, Shi X. Oxidative stress and metal carcinogenesis. Free Radic Biol Med 2012; 53:742-57. [PMID: 22705365 DOI: 10.1016/j.freeradbiomed.2012.06.002] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 05/31/2012] [Accepted: 06/02/2012] [Indexed: 01/18/2023]
Abstract
Occupational and environmental exposures to metals are closely associated with an increased risk of various cancers. Although carcinogenesis caused by metals has been intensively investigated, the exact mechanisms of action are still unclear. Accumulating evidence indicates that reactive oxygen species (ROS) generated by metals play important roles in the etiology of degenerative and chronic diseases. This review covers recent advances in (1) metal-induced generation of ROS and the related mechanisms; (2) the relationship between metal-mediated ROS generation and carcinogenesis; and (3) the signaling proteins involved in metal-induced carcinogenesis, especially intracellular reduction-oxidation-sensitive molecules.
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Affiliation(s)
- Jeong-Chae Lee
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
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Kim TH, Kim YK, Woo JS. The adenosine A3 receptor agonist Cl-IB-MECA induces cell death through Ca²⁺/ROS-dependent down regulation of ERK and Akt in A172 human glioma cells. Neurochem Res 2012; 37:2667-77. [PMID: 22878643 DOI: 10.1007/s11064-012-0855-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 07/19/2012] [Accepted: 07/25/2012] [Indexed: 02/06/2023]
Abstract
Adenosine A(3) receptor (A3AR) is coupled to G proteins that are involved in a variety of intracellular signaling pathways and physiological functions. 2-Chloro-N(6)-(3-iodobenzyl) adenosine-5'-N-methylcarboxamide (Cl-IB-MECA), an agonist of A3AR, has been reported to induce cell death in various cancer cells. However, the effect of CI-IB-MECA on glioma cell growth is not clear. This study was undertaken to examine the effect of CI-IB-MECA on glioma cell viability and to determine its molecular mechanism. CI-IB-MECA inhibited cell proliferation and induced cell death in a dose- and time-dependent manner. Treatment of CI-IB-MECA resulted in an increase in intracellular Ca(2+) followed by enhanced reactive oxygen species (ROS) generation. EGTA and N-acetylcysteine (NAC) blocked the cell death induced by CI-IB-MECA, suggesting that Ca(2+) and ROS are involved in the Cl-IB-MECA-induced cell death. Western blot analysis showed that CI-IB-MECA induced the down-regulation of extracellular signal-regulated kinases (ERK) and Akt, which was prevented by EGTA, NAC, and the A3AR antagonist MRS1191. Transfection of constitutively active forms of MEK, the upstream kinase of ERK, and Akt prevented the cell death. CI-IB-MECA induced caspase-3 activation and the CI-IB-MECA-induced cell death was blocked by the caspase inhibitors DEVD-CHO and z-VAD-FMK. In addition, expression of XIAP and Survivin were decreased in cells treated with Cl-IB-MECA. Collectively, these findings demonstrate that CI-IB-MECA induce a caspase-dependent cell death through suppression of ERK and Akt mediated by an increase in intracellular Ca(2+) and ROS generation in human glioma cells. These suggest that A3AR agonists may be a potential therapeutic agent for induction of apoptosis in human glioma cells.
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Affiliation(s)
- Thae Hyun Kim
- Department of Physiology, School of Medicine, Pusan National University, Beomeo-ri, Mulgeum-eup, Yangsan 626-870, Gyungsangnam-do, Republic of Korea
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Paraquat induces lung alveolar epithelial cell apoptosis via Nrf-2-regulated mitochondrial dysfunction and ER stress. Arch Toxicol 2012; 86:1547-58. [DOI: 10.1007/s00204-012-0873-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 05/16/2012] [Indexed: 12/30/2022]
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Cadmium induces p53-dependent apoptosis in human prostate epithelial cells. PLoS One 2012; 7:e33647. [PMID: 22448262 PMCID: PMC3308998 DOI: 10.1371/journal.pone.0033647] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 02/14/2012] [Indexed: 01/24/2023] Open
Abstract
Cadmium, a widespread toxic pollutant of occupational and environmental concern, is a known human carcinogen. The prostate is a potential target for cadmium carcinogenesis, although the underlying mechanisms are still unclear. Furthermore, cadmium may induce cell death by apoptosis in various cell types, and it has been hypothesized that a key factor in cadmium-induced malignant transformation is acquisition of apoptotic resistance. We investigated the in vitro effects produced by cadmium exposure in normal or tumor cells derived from human prostate epithelium, including RWPE-1 and its cadmium-transformed derivative CTPE, the primary adenocarcinoma 22Rv1 and CWR-R1 cells and LNCaP, PC-3 and DU145 metastatic cancer cell lines. Cells were treated for 24 hours with different concentrations of CdCl2 and apoptosis, cell cycle distribution and expression of tumor suppressor proteins were analyzed. Subsequently, cellular response to cadmium was evaluated after siRNA-mediated p53 silencing in wild type p53-expressing RWPE-1 and LNCaP cells, and after adenoviral p53 overexpression in p53-deficient DU145 and PC-3 cell lines. The cell lines exhibited different sensitivity to cadmium, and 24-hour exposure to different CdCl2 concentrations induced dose- and cell type-dependent apoptotic response and inhibition of cell proliferation that correlated with accumulation of functional p53 and overexpression of p21 in wild type p53-expressing cell lines. On the other hand, p53 silencing was able to suppress cadmium-induced apoptosis. Our results demonstrate that cadmium can induce p53-dependent apoptosis in human prostate epithelial cells and suggest p53 mutation as a possible contributing factor for the acquisition of apoptotic resistance in cadmium prostatic carcinogenesis.
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66
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Nguyen Ngoc TD, Son YO, Lim SS, Shi X, Kim JG, Heo JS, Choe Y, Jeon YM, Lee JC. Sodium fluoride induces apoptosis in mouse embryonic stem cells through ROS-dependent and caspase- and JNK-mediated pathways. Toxicol Appl Pharmacol 2012; 259:329-37. [PMID: 22285274 DOI: 10.1016/j.taap.2012.01.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 01/11/2012] [Accepted: 01/12/2012] [Indexed: 12/19/2022]
Abstract
Sodium fluoride (NaF) is used as a source of fluoride ions in diverse applications. Fluoride salt is an effective prophylactic for dental caries and is an essential element required for bone health. However, fluoride is known to cause cytotoxicity in a concentration-dependent manner. Further, no information is available on the effects of NaF on mouse embryonic stem cells (mESCs). We investigated the mode of cell death induced by NaF and the mechanisms involved. NaF treatment greater than 1mM reduced viability and DNA synthesis in mESCs and induced cell cycle arrest in the G(2)/M phase. The addition of NaF induced cell death mainly by apoptosis rather than necrosis. Catalase (CAT) treatment significantly inhibited the NaF-mediated cell death and also suppressed the NaF-mediated increase in phospho-c-Jun N-terminal kinase (p-JNK) levels. Pre-treatment with SP600125 or z-VAD-fmk significantly attenuated the NaF-mediated reduction in cell viability. In contrast, intracellular free calcium chelator, but not of sodium or calcium ion channel blockers, facilitated NaF-induced toxicity in the cells. A JNK specific inhibitor (SP600125) prevented the NaF-induced increase in growth arrest and the DNA damage-inducible protein 45α. Further, NaF-mediated loss of mitochondrial membrane potential was apparently inhibited by pifithrin-α or CAT inhibitor. These findings suggest that NaF affects viability of mESCs in a concentration-dependent manner, where more than 1mM NaF causes apoptosis through hydroxyl radical-dependent and caspase- and JNK-mediated pathways.
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Affiliation(s)
- Tam Dan Nguyen Ngoc
- Institute of Oral Biosciences and School of Dentistry (BK21 Program), Chonbuk National University, Jeonju 561-756, South Korea
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67
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Arbon KS, Christensen CM, Harvey WA, Heggland SJ. Cadmium exposure activates the ERK signaling pathway leading to altered osteoblast gene expression and apoptotic death in Saos-2 cells. Food Chem Toxicol 2011; 50:198-205. [PMID: 22019892 DOI: 10.1016/j.fct.2011.10.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 10/05/2011] [Accepted: 10/07/2011] [Indexed: 11/19/2022]
Abstract
Recent reports of cadmium in electronic waste and jewelry have increased public awareness regarding this toxic metal. Human exposure to cadmium is associated with the development of osteoporosis. We previously reported cadmium induces apoptosis in human tumor-derived Saos-2 osteoblasts. In this study, we examine the extracellular signal-regulated protein kinase (ERK) and protein kinase C (PKC) pathways in cadmium-induced apoptosis and altered osteoblast gene expression. Saos-2 osteoblasts were cultured in the presence or absence of 10μM CdCl(2) for 2-72h. We detected significant ERK activation in response to CdCl(2) and pretreatment with the ERK inhibitor PD98059 attenuated cadmium-induced apoptosis. However, PKCα activation was not observed after exposure to CdCl(2) and pretreatment with the PKC inhibitor, Calphostin C, was unable to rescue cells from cadmium-induced apoptosis. Gene expression studies were conducted using qPCR. Cells exposed to CdCl(2) exhibited a significant decrease in the bone-forming genes osteopontin (OPN) and alkaline phosphatase (ALP) mRNA. In contrast, SOST, whose protein product inhibits bone formation, significantly increased in response to CdCl(2). Pretreatment with PD98059 had a recovery effect on cadmium-induced changes in gene expression. This research demonstrates cadmium can directly inhibit osteoblasts via ERK signaling pathway and identifies SOST as a target for cadmium-induced osteotoxicity.
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Affiliation(s)
- Kate S Arbon
- Department of Biology, The College of Idaho, 2112 Cleveland Blvd., Caldwell, ID 83605, USA
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68
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Osipov AN, Ryabchenko NI, Ivannik BP, Ryabchenko VI. DNA damage in thymocytes of mice after exposure of the whole body to combined action of cadmium ions and γ radiation. Biophysics (Nagoya-shi) 2011. [DOI: 10.1134/s0006350911050150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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69
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Son YO, Wang X, Hitron JA, Zhang Z, Cheng S, Budhraja A, Ding S, Lee JC, Shi X. Cadmium induces autophagy through ROS-dependent activation of the LKB1-AMPK signaling in skin epidermal cells. Toxicol Appl Pharmacol 2011; 255:287-96. [PMID: 21767558 DOI: 10.1016/j.taap.2011.06.024] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 06/29/2011] [Accepted: 06/30/2011] [Indexed: 12/17/2022]
Abstract
Cadmium is a toxic heavy metal which is environmentally and occupationally relevant. The mechanisms underlying cadmium-induced autophagy are not yet completely understood. The present study shows that cadmium induces autophagy, as demonstrated by the increase of LC3-II formation and the GFP-LC3 puncta cells. The induction of autophagosomes was directly visualized by electron microscopy in cadmium-exposed skin epidermal cells. Blockage of LKB1 or AMPK by siRNA transfection suppressed cadmium-induced autophagy. Cadmium-induced autophagy was inhibited in dominant-negative AMPK-transfected cells, whereas it was accelerated in cells transfected with the constitutively active form of AMPK. mTOR signaling, a negative regulator of autophagy, was downregulated in cadmium-exposed cells. In addition, cadmium generated reactive oxygen species (ROS) at relatively low levels, and caused poly(ADP-ribose) polymerase-1 (PARP) activation and ATP depletion. Inhibition of PARP by pharmacological inhibitors or its siRNA transfection suppressed ATP reduction and autophagy in cadmium-exposed cells. Furthermore, cadmium-induced autophagy signaling was attenuated by either exogenous addition of catalase and superoxide dismutase, or by overexpression of these enzymes. Consequently, these results suggest that cadmium-mediated ROS generation causes PARP activation and energy depletion, and eventually induces autophagy through the activation of LKB1-AMPK signaling and the down-regulation of mTOR in skin epidermal cells.
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Affiliation(s)
- Young-Ok Son
- Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305, USA
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70
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Li X, Qian J, Wang C, Zheng K, Ye L, Fu Y, Han N, Bian H, Pan J, Wang J, Zhu M. Regulating cytoplasmic calcium homeostasis can reduce aluminum toxicity in yeast. PLoS One 2011; 6:e21148. [PMID: 21698264 PMCID: PMC3115986 DOI: 10.1371/journal.pone.0021148] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 05/20/2011] [Indexed: 12/11/2022] Open
Abstract
Our previous study suggested that increased cytoplasmic calcium (Ca) signals may mediate aluminum (Al) toxicity in yeast (Saccharomyces cerevisiae). In this report, we found that a yeast mutant, pmc1, lacking the vacuolar calcium ion (Ca2+) pump Ca2+-ATPase (Pmc1p), was more sensitive to Al treatment than the wild-type strain. Overexpression of either PMC1 or an anti-apoptotic factor, such as Bcl-2, Ced-9 or PpBI-1, decreased cytoplasmic Ca2+ levels and rescued yeast from Al sensitivity in both the wild-type and pmc1 mutant. Moreover, pretreatment with the Ca2+ chelator BAPTA-AM sustained cytoplasmic Ca2+ at low levels in the presence of Al, effectively making the cells more tolerant to Al exposure. Quantitative RT-PCR revealed that the expression of calmodulin (CaM) and phospholipase C (PLC), which are in the Ca2+ signaling pathway, was down-regulated under Al stress. This effect was largely counteracted when cells overexpressed anti-apoptotic Ced-9 or were pretreated with BAPTA-AM. Taken together, our results suggest that the negative regulation of Al-induced cytoplasmic Ca signaling is a novel mechanism underlying internal resistance to Al toxicity.
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Affiliation(s)
- Xuan Li
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Jia Qian
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Chaoqun Wang
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Ke Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Lan Ye
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yu Fu
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Ning Han
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Hongwu Bian
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
- * E-mail: (MZ); (HB)
| | - Jianwei Pan
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, China
| | - Junhui Wang
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Muyuan Zhu
- State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China
- * E-mail: (MZ); (HB)
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Hamann I, König C, Richter C, Jahnke G, Hartwig A. Impact of cadmium on hOGG1 and APE1 as a function of the cellular p53 status. Mutat Res 2011; 736:56-63. [PMID: 21605570 DOI: 10.1016/j.mrfmmm.2011.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 04/18/2011] [Accepted: 05/07/2011] [Indexed: 11/16/2022]
Abstract
The tumor suppressor protein p53, often called the guardian of the genome, is involved in important cellular processes, such as cell cycle control, apoptosis and DNA repair. With respect to BER, p53 might physically interact with and affect the transcription of different BER proteins such as hOGG1, APE1 or Polβ. In studies in HCT116 p53(-/-) cells previously published, activity and mRNA expression of hOGG1 were found to be significantly decreased, while down-regulation of APE1 mRNA and protein levels in response to genotoxic stress were only described in HCT116 p53(+/+) cells, but not in the isogenic p53 knockout cell line. The predominantly indirect genotoxic carcinogen cadmium inhibits the BER pathway and potentially interferes with zinc binding proteins such as p53. Therefore, this study was accomplished to investigate whether p53 is involved in the cadmium-induced inhibition of BER activity. To address this issue we applied a non-radioactive cleavage test system based on a Cy5-labeled oligonucleotide. We present evidence that p53 is not essential for hOGG1 and APE1 gene expression as well as OGG and APE activity in unstressed HCT116 cells; however, it plays an important role in the cellular response to cadmium treatment. Here, a direct involvement of p53 was only observed with respect to APE1 gene expression contributing to an altered APE activity, while OGG activity was presumably affected indirectly due to a stronger accumulation of cadmium in HCT116 p53(+/+) cells. In summary, p53 indeed affects the BER pathway directly and indirectly in response to cadmium treatment.
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Affiliation(s)
- Ingrit Hamann
- Institut für Angewandte Biowissenschaften, Abteilung Lebensmittelchemie und Toxikologie, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany
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72
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Calcium signaling is involved in cadmium-induced neuronal apoptosis via induction of reactive oxygen species and activation of MAPK/mTOR network. PLoS One 2011; 6:e19052. [PMID: 21544200 PMCID: PMC3081326 DOI: 10.1371/journal.pone.0019052] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 03/23/2011] [Indexed: 11/19/2022] Open
Abstract
Cadmium (Cd), a toxic environmental contaminant, induces oxidative stress, leading to neurodegenerative disorders. Recently we have demonstrated that Cd induces neuronal apoptosis in part by activation of the mitogen-activated protein kineses (MAPK) and mammalian target of rapamycin (mTOR) pathways. However, the underlying mechanism remains elusive. Here we show that Cd elevated intracellular calcium ion ([Ca²+](i)) level in PC12, SH-SY5Y cells and primary murine neurons. BAPTA/AM, an intracellular Ca²+ chelator, abolished Cd-induced [Ca²+](i) elevation, and blocked Cd activation of MAKPs including extracellular signal-regulated kinase 1/2 (Erk1/2), c-Jun N-terminal kinase (JNK) and p38, and mTOR-mediated signaling pathways, as well as cell death. Pretreatment with the extracellular Ca²+ chelator EGTA also prevented Cd-induced [Ca²+](i) elevation, MAPK/mTOR activation, as well as cell death, suggesting that Cd-induced extracellular Ca²+ influx plays a critical role in contributing to neuronal apoptosis. In addition, calmodulin (CaM) antagonist trifluoperazine (TFP) or silencing CaM attenuated the effects of Cd on MAPK/mTOR activation and cell death. Furthermore, Cd-induced [Ca²+](i) elevation or CaM activation resulted in induction of reactive oxygen species (ROS). Pretreatment with BAPTA/AM, EGTA or TFP attenuated Cd-induced ROS and cleavage of caspase-3 in the neuronal cells. Our findings indicate that Cd elevates [Ca²+](i), which induces ROS and activates MAPK and mTOR pathways, leading to neuronal apoptosis. The results suggest that regulation of Cd-disrupted [Ca²+](i) homeostasis may be a new strategy for prevention of Cd-induced neurodegenerative diseases.
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73
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Liu S, Han Y, Zhang T, Yang Z. Protective effect of trifluoperazine on hydrogen peroxide-induced apoptosis in PC12 cells. Brain Res Bull 2010; 84:183-8. [PMID: 21172409 DOI: 10.1016/j.brainresbull.2010.12.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 12/02/2010] [Accepted: 12/12/2010] [Indexed: 01/25/2023]
Abstract
This study investigated effects of trifluoperazine (TFP) against the cytotoxicity induced by H₂O₂ in PC12 cells and the mechanisms thereof. Different concentrations of H₂O₂ (100-500 μM) induced a significant decrease in cell viability accompanied by increased oxidative stress and cell apoptosis. Pretreatment with TFP inhibited H₂O₂-induced cell viability loss. The flow cytometric assay showed that TFP can inhibit intracellular reactive oxygen species (ROS) generation and reduce the cell apoptosis. The electrophysiological recordings indicated that when treated with H₂O₂, the calcium current was significantly increased. Pretreatment with TFP increased mitochondrial membrane potential (MMP) in cells of oxidative injury. These results suggested that TFP can reduce apoptosis by inhibiting ROS generation and preventing loss of MMP in cells. Meanwhile, the protective effect of TFP on the cell apoptosis may be related to the calcium overload. TFP may inhibit the calcium overload process to achieve the protection against apoptosis.
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Affiliation(s)
- Shichang Liu
- School of Medicine, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, China
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74
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Son YO, Hitron JA, Cheng S, Budhraja A, Zhang Z, Lan Guo N, Lee JC, Shi X. The dual roles of c-Jun NH2-terminal kinase signaling in Cr(VI)-induced apoptosis in JB6 cells. Toxicol Sci 2010; 119:335-45. [PMID: 21047991 DOI: 10.1093/toxsci/kfq335] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Occupational exposure to chromium (Cr) compounds has been shown to cause serious toxic and carcinogenic effects. The skin is an important target for the compounds in industrially exposed Cr workers. c-Jun NH(2)-terminal kinase (JNK) regulates cell proliferation, apoptosis, and differentiation. This protein's effects on cellular response depend upon the cell type and stimuli. The mechanisms by which hexavalent chromium (Cr(VI)) leads to apoptosis in the skin are unclear at present. The aim of this study is to examine whether JNK regulates apoptosis in Cr(VI)-exposed mouse JB6 epidermal cells. The present study showed that Cr(VI) induced apoptotic cell death through JNK activation. The blockage of JNK by small interference RNA (si-RNA) transfection suppressed Cr(VI)-induced apoptotic cell death with the concomitant downregulation of antiapoptotic Bcl-2 family proteins, mitochondrial membrane depolarization (Δψm), caspase activation, and poly (ADP-ribose) polymerase cleavage. However, inhibition of c-Jun expression by si-RNA transfection enhanced cytotoxicity, which corresponded to increasing apoptosis and Δψm. This phenomenon is associated with p53 activation caused by increasing reactive oxygen species (ROS) levels because of the downregulation of superoxide dismutase expression in si-c-Jun-transfected cells. Taken together, Cr(VI) induces apoptosis via JNK-mediated signaling, whereas c-Jun activation acts as an inhibitor of apoptotic signaling. Additionally, ROS generated by Cr(VI) is a pivotal regulator of JNK.
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Affiliation(s)
- Young-Ok Son
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536-0305, USA
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75
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Rai A, Maurya SK, Khare P, Srivastava A, Bandyopadhyay S. Characterization of developmental neurotoxicity of As, Cd, and Pb mixture: synergistic action of metal mixture in glial and neuronal functions. Toxicol Sci 2010; 118:586-601. [PMID: 20829427 DOI: 10.1093/toxsci/kfq266] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neurotoxicity of individual metals is well investigated but that of metal mixture (MM), an environmental reality, in the developing brain is relatively obscure. We investigated the combinatorial effect of arsenic (As), cadmium (Cd), and lead (Pb) on rat brain development, spanning in utero to postnatal development. MM was administered by gavage to pregnant and lactating rats, and to postweaning pups till 2 months. The pups exhibited behavioral disturbances characterized by hyperlocomotion, increased grip strength, and learning-memory deficit. Disruption of the blood-brain barrier (BBB) was associated with dose-dependent increase in deposition of the metals in developing brain. Astrocytes were affected by MM treatment as evident from their reduced density, area, perimeter, compactness, and number of processes, and increased apoptosis in cerebral cortex and cerebellum. The metals induced synergistic reduction in glial fibrillary acidic protein (GFAP) expression during brain development; however, postweaning withdrawal of MM partially restored the levels of GFAP in adults. To characterize the toxic mechanism, we treated rat primary astrocytes with MM at concentrations ranging from lethal concentration (LC)(10) to LC(75) of the metals. We observed synergistic downregulation in viability and increase in apoptosis of the astrocytes, which were induced by proximal activation of extra cellular signal-regulated kinase (ERK) signaling and downstream activation of Jun N-terminal kinase (JNK) pathway. Furthermore, rise in intracellular calcium ion ([Ca(2+)](i)) and reactive oxygen species generation promoted apoptosis in the astrocytes. Taken together, these observations are the first to show that mixture of As, Cd, and Pb has the capacity to induce synergistic toxicity in astrocytes that may compromise the BBB and may cause behavioral dysfunction in developing rats.
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Affiliation(s)
- Asit Rai
- Developmental Toxicology Division, Indian Institute of Toxicology Research, Council of Scientific and Industrial Research, Lucknow 226001, India
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