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Zhang A, Wei P, Ding L, Zhang H, Jiang Z, Mi L, Yu F, Tang M. Associations of serum lead, cadmium, and mercury concentrations with all-cause and cause-specific mortality among individuals with cardiometabolic multimorbidity. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 280:116556. [PMID: 38852466 DOI: 10.1016/j.ecoenv.2024.116556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 06/02/2024] [Accepted: 06/04/2024] [Indexed: 06/11/2024]
Abstract
Epidemiological evidence indicates an association between exposure to toxic metals and the occurrence of cardiometabolic diseases (CMDs). However, the impact of exposure to harmful metallic elements, such as lead (Pb), cadmium (Cd), and mercury (Hg), on mortality in individuals with cardiometabolic multimorbidity (CMM) remains uncertain. Therefore, in this study, we analyzed data from 4139 adults diagnosed with CMM from the National Health and Nutrition Examination Survey 1999-2016. CMM was defined as the presence of at least two CMDs (hypertension, diabetes, stroke, and coronary artery disease). Over an average follow-up period of 9.0 years, 1379 deaths from all causes, 515 deaths related to cardiovascular disease (CVD), and 215 deaths attributable to cancer were recorded. After adjusting for potential covariates, serum Pb concentrations were not associated with all-cause, CVD, or cancer mortality. Participants exposed to Cd had an elevated risk of all-cause mortality (hazard ratio [HR], 1.23; 95 % CI, 1.16-1.30), CVD-related mortality (HR, 1.23; 95 % CI, 1.12-1.35), and cancer-related mortality (HR, 1.29; 95 % CI, 1.13-1.47). Participants with serum Hg levels in the highest quantile had lower risks of all-cause (HR, 0.64; 95 % CI, 0.52-0.80) and CVD-related (HR, 0.62; 95 % CI, 0.44-0.88) mortality than did those in the lowest quantile. Stratified analyses revealed significant interactions between serum Cd concentrations and age for CVD-related mortality (P for interaction =0.011), indicating that CMM participants aged < 60 years who were exposed to Cd were at a greater risk of CVD-related mortality. A nonlinear relationship was observed between serum Cd concentrations and all-cause (P for nonlinear relationship = 0.012) and CVD-related (P for nonlinear relationship < 0.001) mortality. Minimizing Cd exposure in patients with CMM may help prevent premature death.
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Affiliation(s)
- Aikai Zhang
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Cardiovascular Institute, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China
| | - Peijian Wei
- Department of Structural Heart Disease, National Center for Cardiovascular Disease, China & Fuwai Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Lei Ding
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Cardiovascular Institute, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China
| | - Hongda Zhang
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Cardiovascular Institute, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China
| | - Zihan Jiang
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Cardiovascular Institute, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China
| | - Lijie Mi
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Cardiovascular Institute, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China
| | - Fengyuan Yu
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Cardiovascular Institute, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China
| | - Min Tang
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Cardiovascular Institute, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China.
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Ali Hussein M, Kamalakkannan A, Valinezhad K, Kannan J, Paleati N, Saad R, Kajdacsy-Balla A, Munirathinam G. The dynamic face of cadmium-induced Carcinogenesis: Mechanisms, emerging trends, and future directions. Curr Res Toxicol 2024; 6:100166. [PMID: 38706786 PMCID: PMC11068539 DOI: 10.1016/j.crtox.2024.100166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/18/2024] [Accepted: 04/03/2024] [Indexed: 05/07/2024] Open
Abstract
Cadmium (Cd) is a malleable element with odorless, tasteless characteristics that occurs naturally in the earth's crust, underground water, and soil. The most common reasons for the anthropological release of Cd to the environment include industrial metal mining, smelting, battery manufacturing, fertilizer production, and cigarette smoking. Cadmium-containing products may enter the environment as soluble salts, vapor, or particle forms that accumulate in food, soil, water, and air. Several epidemiological studies have highlighted the association between Cd exposure and adverse health outcomes, especially renal toxicity, and the impact of Cd exposure on the development and progression of carcinogenesis. Also highlighted is the evidence for early-life and even maternal exposure to Cd leading to devastating health outcomes, especially the risk of cancer development in adulthood. Several mechanisms have been proposed to explain how Cd mediates carcinogenic transformation, including epigenetic alteration, DNA methylation, histone posttranslational modification, dysregulated non-coding RNA, DNA damage in the form of DNA mutation, strand breaks, and chromosomal abnormalities with double-strand break representing the most common DNA form of damage. Cd induces an indirect genotoxic effect by reducing p53's DNA binding activity, eventually impairing DNA repair, inducing downregulation in the expression of DNA repair genes, which might result in carcinogenic transformation, enhancing lipid peroxidation or evasion of antioxidant interference such as catalase, superoxide dismutase, and glutathione. Moreover, Cd mediates apoptosis evasion, autophagy activation, and survival mechanisms. In this review, we decipher the role of Cd mediating carcinogenic transformation in different models and highlight the interaction between various mechanisms. We also discuss diagnostic markers, therapeutic interventions, and future perspectives.
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Affiliation(s)
- Mohamed Ali Hussein
- Department of Pharmaceutical Services, Children’s Cancer Hospital Egypt, 57357 Cairo, Egypt
- Institute of Global Health and Human Ecology (IGHHE), School of Sciences and Engineering, The American University in Cairo, New Cairo 11835, Egypt
| | - Abishek Kamalakkannan
- Department of Biomedical Sciences, College of Medicine, University of Illinois, Rockford, IL 61107, USA
| | - Kamyab Valinezhad
- Department of Biomedical Sciences, College of Medicine, University of Illinois, Rockford, IL 61107, USA
| | - Jhishnuraj Kannan
- Department of Biomedical Sciences, College of Medicine, University of Illinois, Rockford, IL 61107, USA
| | - Nikhila Paleati
- Department of Psychology and Neuroscience, College of Undergraduate Studies, Nova Southeastern University, Fort Lauderdale, FL 33328, USA
| | - Rama Saad
- Department of Hematology/Oncology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - André Kajdacsy-Balla
- Department of Pathology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Gnanasekar Munirathinam
- Department of Biomedical Sciences, College of Medicine, University of Illinois, Rockford, IL 61107, USA
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Shahzadi A, Tariq N, Sonmez H, Waquar S, Zahid A, Javed MA, Ashraf MY, Malik A, Ozturk M. Potential effect of luteolin, epiafzelechin, and albigenin on rats under cadmium-induced inflammatory insult: In silico and in vivo approach. Front Chem 2023; 11:1036478. [PMID: 36936530 PMCID: PMC10016615 DOI: 10.3389/fchem.2023.1036478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 01/19/2023] [Indexed: 03/06/2023] Open
Abstract
Introduction: Cadmium(Cd) an industrial poison present abundantly in the environment, causes human toxicity by an inflammatory process. Chronic exposure of cadmium can cause a number of molecular lesions that could be relevant to oncogenesis, through indirect or epigenetic mechanisms, potentially including abnormal activation of oncogenes and suppression of apoptosis by depletion of antioxidants. As induction of cyclooxygenase (COX)-2 is linked to inflammatory processes, use of luteolin, epiafzelechin, and albigenin alone or in different combinations may be used as anti-inflammatory therapeutic agents. Methods: We, herein, performed in silico experiments to check the binding affinity of phytochemicals and their therapeutic effect against COX-2 in cadmium administered rats. Wistar albino rats were given phytochemicals in different combinations to check their anti-inflammatory activities against cadmium intoxication. The level of alanine aminotransferases (ALT), 4-hydroxynonenal (4HNE), 8-hydroxy-2-deoxyguanosine (8-OHdG), tumor necrosis factor-alpha (TNF-α), isoprostanes (IsoP-2α), COX-2, and malondialdehyde (MDA) were estimated with their respective ELISA and spectrophotometric methods. Results: The generated results show that phytocompounds possessed good binding energy potential against COX-2, and common interactive behavior was observed in all docking studies. Moreover, the level of ALT, 4HNE, 8-OHdG, TNF-α, IsoP-2α, malondialdehyde, and COX-2 were significantly increased in rats with induced toxicity compared to the control group, whereas in combinational therapy of phytocompounds, the levels were significantly decreased in the group. Discussion: Taken together, luteolin, epiafzelechin, and albigenin can be used as anti-inflammatory therapeutic agents for future novel drug design, and thus it may have therapeutic importance against cadmium toxicity.
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Affiliation(s)
- Andleeb Shahzadi
- Department of Medical Pharmacology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkiye
| | - Nusrat Tariq
- Department of Physiology, M. Islam Medical and Dental College, Gujranwala, Pakistan
| | - Haktan Sonmez
- Department of Medical Pharmacology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkiye
| | - Sulayman Waquar
- School of Biochemistry, Minhaj University Lahore, Lahore, Pakistan
| | - Ayesha Zahid
- Institute of Molecular Biology and Biotechnology (IMBB), The University of Lahore, Lahore, Pakistan
| | | | - Muhammad Yasin Ashraf
- Institute of Molecular Biology and Biotechnology (IMBB), The University of Lahore, Lahore, Pakistan
| | - Arif Malik
- Institute of Molecular Biology and Biotechnology (IMBB), The University of Lahore, Lahore, Pakistan
| | - Munir Ozturk
- Centre for Environmental Studies, Ege University, Izmir, Turkiye
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Li Z, Fan Y, Tao C, Yan W, Huang Y, Qian H, Xu Q, Wan T, Chen Y, Qin Y, Lu C. Association between exposure to cadmium and risk of all-cause and cause-specific mortality in the general US adults: A prospective cohort study. CHEMOSPHERE 2022; 307:136060. [PMID: 35981619 DOI: 10.1016/j.chemosphere.2022.136060] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/15/2022] [Accepted: 08/09/2022] [Indexed: 05/25/2023]
Abstract
BACKGROUND Cadmium has been suggested to accumulate in the body over a lifetime, posing a great threat to human health. So far, few studies have studied the association between cadmium exposure and long-term health outcomes in adults. OBJECTIVES To investigate the risk of mortality with blood cadmium level in adults (participants of NHANES, 1999-2014). METHODS We evaluated the associations between cadmium and risk of mortality. Data on mortality and cadmium exposure were collected in NHANES database including 39,865 participants. Multivariate Cox regression models were established for calculating hazard ratios (HRs) and 95%CI between cadmium exposure and all-cause and specific-cause mortality outcomes. RESULTS Totally, 39,865 individuals with 19,260 males (48.3%) and 20,605 females (51.7%) were included in the study. During a total of 341,017 person-years of follow-up 5,094 deaths were documented, including 1,067 cardiovascular disease (CVD) and 890 cancers. Compared with the lowest quantile of cadmium exposure level group, the adjusted HRs in the highest quantile cadmium exposure level group were 1.73 (95%CI: 1.52-1.97) for all-cause mortality, 1.72 (95%CI: 1.28-2.30) for CVD mortality and 1.87 (95%CI: 1.49-2.36) for cancer mortality, respectively (P for trend: <0.001). Additionally, significant interactions with smoking status in the stratified analyses of all-cause mortality and cancer mortality, age in the stratified analyses of cancer mortality were found (P for interaction: 0.002, <0.001 and 0.012). CONCLUSIONS In this nationwide representative sample of the population, we found that higher blood cadmium concentration was associated with increased risks of all-cause and specific-cause mortality. These data further evidence the link between mortality and cadmium concentration. It is of great importance for both policy makers and the public to minimize cadmium exposure, and to reduce long-term adverse health effects.
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Affiliation(s)
- Zhi Li
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Yun Fan
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Department of Microbes and Infection, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Chengzhe Tao
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Wenkai Yan
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Yuna Huang
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Hong Qian
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Qiaoqiao Xu
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Tingya Wan
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Yiyuan Chen
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Yufeng Qin
- Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Department of Microbes and Infection, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.
| | - Chuncheng Lu
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.
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5
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Manić L, Wallace D, Onganer PU, Taalab YM, Farooqi AA, Antonijević B, Buha Djordjevic A. Epigenetic mechanisms in metal carcinogenesis. Toxicol Rep 2022; 9:778-787. [PMID: 36561948 PMCID: PMC9764177 DOI: 10.1016/j.toxrep.2022.03.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/16/2022] [Accepted: 03/26/2022] [Indexed: 12/25/2022] Open
Abstract
Many metals exhibit genotoxic and/or carcinogenic effects. These toxic metals can be found ubiquitously - in drinking water, food, air, general use products, in everyday and occupational settings. Exposure to such carcinogenic metals can result in serious health disorders, including cancer. Arsenic, cadmium, chromium, nickel, and their compounds have already been recognized as carcinogens by the International Agency for Research on Cancer. This review summarizes a wide range of epigenetic mechanisms contributing to carcinogenesis induced by these metals, primarily including, but not limited to, DNA methylation, miRNA regulation, and histone posttranslational modifications. The mechanisms are described and discussed both from a metal-centric and a mechanism-centric standpoint. The review takes a broad perspective, putting the mechanisms in the context of real-life exposure, and aims to assist in guiding future research, particularly with respect to the assessment and control of exposure to carcinogenic metals and novel therapy development.
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Affiliation(s)
- Luka Manić
- Department of Toxicology “Akademik Danilo Soldatović”, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - David Wallace
- School of Biomedical Science, Oklahoma State University Center for Health Sciences, Tulsa, United States
| | - Pinar Uysal Onganer
- Cancer Research Group, School of Life Sciences, University of Westminster, London, UK
| | - Yasmeen M. Taalab
- Institute of Forensic and Traffic Medicine, University of Heidelberg, Voßstraße 2, 69115 Heidelberg, Germany,Forensic Medicine and Clinical Toxicology Department, Faculty of Medicine, Mansoura University, Dakahlia Governate 35516, Egypt
| | - Ammad Ahmad Farooqi
- Laboratory for Translational Oncology and Personalized Medicine, RLMC, Lahore, Pakistan
| | - Biljana Antonijević
- Department of Toxicology “Akademik Danilo Soldatović”, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Aleksandra Buha Djordjevic
- Department of Toxicology “Akademik Danilo Soldatović”, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia,Correspondence to: Department of Toxicology “Akademik Danilo Soldatović”, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
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Abstract
Metal exposure is pervasive and not limited to sporadic poisoning events or toxic waste sites. Hundreds of millions of people around the globe are affected by chronic metal exposure, which is associated with serious health concerns, including cancer, as demonstrated in a variety of studies at the molecular, systemic, and epidemiologic levels. Metal-induced toxicity and carcinogenicity are sophisticated and complex in nature. This review provides a broad context and holistic view of currently available studies on the mechanisms of metal-induced carcinogenesis. Specifically, we focus on the five most prevalent carcinogenic metals, arsenic, nickel, cadmium, chromium, and beryllium, and their potential to drive carcinogenesis in humans. A comprehensive understanding of the mechanisms behind the development of metal-induced cancer can provide valuable insights for therapeutic intervention involving molecular targets in metal-induced carcinogenesis.
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Affiliation(s)
- Qiao Yi Chen
- Departments of Environmental Medicine, and Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10010, USA;
| | - Thomas DesMarais
- Departments of Environmental Medicine, and Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10010, USA;
| | - Max Costa
- Departments of Environmental Medicine, and Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10010, USA;
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Matthews NH, Fitch K, Li WQ, Morris JS, Christiani DC, Qureshi AA, Cho E. Exposure to Trace Elements and Risk of Skin Cancer: A Systematic Review of Epidemiologic Studies. Cancer Epidemiol Biomarkers Prev 2019; 28:3-21. [PMID: 30297516 PMCID: PMC6324965 DOI: 10.1158/1055-9965.epi-18-0286] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 07/30/2018] [Accepted: 09/28/2018] [Indexed: 12/11/2022] Open
Abstract
Exposure to environmental trace elements has been studied in relation to many cancers. However, an association between exposure to trace elements and skin cancer remains less understood. Therefore, we conducted a systematic review of published epidemiologic literature examining the association between exposure to trace elements, and risk of melanoma and keratinocyte carcinoma in humans. We identified epidemiologic studies investigating exposure to arsenic, cadmium, chromium, copper, iron, selenium, and zinc and risk of skin cancer in humans. Among the minerals, arsenic, selenium, and zinc had more than five studies available. Exposure to arsenic was associated with increased risk of keratinocyte carcinoma, while too few studies existed on melanoma to draw conclusions. Exposure to selenium was associated with possible increased risk of keratinocyte carcinoma. Studies of zinc and skin cancer were case-control in design and were found to have inconsistent associations. The data on the association between cadmium, chromium, copper, and iron and risk of skin cancer remain too sparse to draw any conclusions. In summary, epidemiologic studies on exposure to trace elements and cutaneous malignancies are limited. Studies with larger sample sizes and prospective designs are warranted to improve our knowledge of trace elements and skin cancer.
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Affiliation(s)
- Natalie H Matthews
- Department of Dermatology, The Warren Alpert Medical School, Brown University, Providence, Rhode Island
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Katherine Fitch
- Department of Dermatology, The Warren Alpert Medical School, Brown University, Providence, Rhode Island
| | - Wen-Qing Li
- Department of Dermatology, The Warren Alpert Medical School, Brown University, Providence, Rhode Island
- Department of Epidemiology, Brown University School of Public Health, Providence, Rhode Island
| | - J Steven Morris
- Research Reactor Center, University of Missouri-Columbia and Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri
| | - David C Christiani
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
- Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
- Pulmonary and Critical Care Unit, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts
| | - Abrar A Qureshi
- Department of Dermatology, The Warren Alpert Medical School, Brown University, Providence, Rhode Island
- Department of Epidemiology, Brown University School of Public Health, Providence, Rhode Island
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
- Department of Dermatology, Rhode Island Hospital, Providence, Rhode Island
| | - Eunyoung Cho
- Department of Dermatology, The Warren Alpert Medical School, Brown University, Providence, Rhode Island.
- Department of Epidemiology, Brown University School of Public Health, Providence, Rhode Island
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
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Venza M, Visalli M, Biondo C, Oteri R, Agliano F, Morabito S, Caruso G, Caffo M, Teti D, Venza I. Epigenetic effects of cadmium in cancer: focus on melanoma. Curr Genomics 2015; 15:420-35. [PMID: 25646071 PMCID: PMC4311387 DOI: 10.2174/138920291506150106145932] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 11/07/2014] [Accepted: 11/17/2014] [Indexed: 01/01/2023] Open
Abstract
Cadmium is a highly toxic heavy metal, which has a destroying impact on organs. Exposure to cadmium causes severe health problems to human beings due to its ubiquitous environmental presence and features of the pathologies associated with pro-longed exposure. Cadmium is a well-established carcinogen, although the underlying mechanisms have not been fully under-stood yet. Recently, there has been considerable interest in the impact of this environmental pollutant on the epigenome. Be-cause of the role of epigenetic alterations in regulating gene expression, there is a potential for the integration of cadmium-induced epigenetic alterations as critical elements in the cancer risk assessment process. Here, after a brief review of the ma-jor diseases related to cadmium exposure, we focus our interest on the carcinogenic potential of this heavy metal. Among the several proposed pathogenetic mechanisms, particular attention is given to epigenetic alterations, including changes in DNA methylation, histone modifications and non-coding RNA expression. We review evidence for a link between cadmium-induced epigenetic changes and cell transformation, with special emphasis on melanoma. DNA methylation, with reduced expression of key genes that regulate cell proliferation and apoptosis, has emerged as a possible cadmium-induced epigenetic mechanism in melanoma. A wider comprehension of mechanisms related to this common environmental contaminant would allow a better cancer risk evaluation.
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Affiliation(s)
- Mario Venza
- Department of Experimental Specialistic Medical, Surgical and Odontostomatology Sciences, University of Messina, Messina, Italy
| | - Maria Visalli
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Carmelo Biondo
- Department of Pediatric, Gynecological, Microbiological and Biomedical Sciences, University of Messina, Messina, Italy
| | - Rosaria Oteri
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Federica Agliano
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Silvia Morabito
- Department of Experimental Specialistic Medical, Surgical and Odontostomatology Sciences, University of Messina, Messina, Italy
| | - Gerardo Caruso
- Department of Neurosciences, University of Messina, Messina, Italy
| | - Maria Caffo
- Department of Neurosciences, University of Messina, Messina, Italy
| | - Diana Teti
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Isabella Venza
- Department of Experimental Specialistic Medical, Surgical and Odontostomatology Sciences, University of Messina, Messina, Italy
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Martín SA, Emilio R, Mahara V. Role of oxidative stress in transformation induced by metal mixture. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2011; 2011:935160. [PMID: 22191014 PMCID: PMC3236433 DOI: 10.1155/2011/935160] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 09/07/2011] [Indexed: 01/24/2023]
Abstract
Metals are ubiquitous pollutants present as mixtures. In particular, mixture of arsenic-cadmium-lead is among the leading toxic agents detected in the environment. These metals have carcinogenic and cell-transforming potential. In this study, we used a two step cell transformation model, to determine the role of oxidative stress in transformation induced by a mixture of arsenic-cadmium-lead. Oxidative damage and antioxidant response were determined. Metal mixture treatment induces the increase of damage markers and the antioxidant response. Loss of cell viability and increased transforming potential were observed during the promotion phase. This finding correlated significantly with generation of reactive oxygen species. Cotreatment with N-acetyl-cysteine induces effect on the transforming capacity; while a diminution was found in initiation, in promotion phase a total block of the transforming capacity was observed. Our results suggest that oxidative stress generated by metal mixture plays an important role only in promotion phase promoting transforming capacity.
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Affiliation(s)
- Silva-Aguilar Martín
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria 04510, DF Mexico
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Odewumi CO, Buggs R, Badisa VLD, Latinwo LM, Badisa RB, Ikediobi CO, Darling-Reed SF, Owens MA. Mitigative action of monoisoamyl-2,3-dimercaptosuccinate (MiADMS) against cadmium-induced damage in cultured rat normal liver cells. Toxicol In Vitro 2011; 25:1733-9. [PMID: 21911053 PMCID: PMC3322667 DOI: 10.1016/j.tiv.2011.08.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 08/22/2011] [Accepted: 08/29/2011] [Indexed: 10/17/2022]
Abstract
Cadmium is non-essential, carcinogenic and multitarget pollutant in the environment. Monoisoamyl-2,3-dimercaptosuccinate (MiADMS) is an ester of dimercaptosuccinic acid that acts as an antioxidant and chelator. Therefore, the mitigative action of MiADMS on viability, morphology, antioxidative enzymes and cell cycle were studied on rat liver cells treated with cadmium chloride (CdCl2). The cells were treated with 150 μM CdCl2 alone or cotreated with 300 μM MiADMS (concurrently, 2 h or 4 h post-CdCl2 treatment) for 24 h. The viability of cells treated with CdCl2 alone was decreased in comparison to the control cells. Cotreatment with MiADMS resulted in an increase in cell viability in comparison to the CdCl2 alone treated cells. The CdCl2 treatment altered the morphological shape of the cells, while cotreatment with MiADMS restored the shape. Antioxidative enzymes activities were decreased in the cells treated with CdCl2 alone, while MiADMS cotreatment resulted in an increase in enzyme activities. The CdCl2 arrested the cells in S phase of the cell cycle. Cotreatment with MiADMS alleviated cell cycle arrest by shifting to G1 phase. These results clearly show the mitigative action of MiADMS on CdCl2 toxicity and may suggest that MiADMS can be used as an antidote against cadmium.
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Affiliation(s)
- Caroline O Odewumi
- Department of Biology, Florida A&M University, Tallahassee, FL 32307, USA.
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Tandogan B, Ulusu NN. Effects of cadmium and zinc ions on purified lamb kidney cortex glucose-6-phosphate dehydrogenase activity. J Enzyme Inhib Med Chem 2008; 21:225-30. [PMID: 16789437 DOI: 10.1080/14756360500480533] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Glucose-6-phosphate dehydrogenase (G-6-PD) is the first enzyme in the pentose phosphate pathway. Cadmium is a toxic heavy metal that inhibits several enzymes. Zinc is an essential metal but overdoses of zinc have toxic effects on enzyme activities. In this study G-6-PD from lamb kidney cortex was competitively inhibited by zinc both with respect to glucose-6-phosphate (G-6-P) and NADP+ with Ki values of 1.066 +/- 0.106 and 0.111 +/- 0.007 mM respectively whereas cadmium was a non-competitive inhibitor with respect to both G-6-P and NADP+ Ki values of 2.028 +/- 0.175 and 2.044 +/- 0.289 mM respectively.
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Affiliation(s)
- Berivan Tandogan
- Hacettepe University, Faculty of Medicine, Department of Biochemistry, 06100 Ankara, Turkey
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Jiang G, Xu L, Song S, Zhu C, Wu Q, Zhang L, Wu L. Effects of long-term low-dose cadmium exposure on genomic DNA methylation in human embryo lung fibroblast cells. Toxicology 2008; 244:49-55. [PMID: 18077075 DOI: 10.1016/j.tox.2007.10.028] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 10/26/2007] [Accepted: 10/28/2007] [Indexed: 11/25/2022]
Abstract
Cadmium is a toxic transition metal of continuing occupational and environmental concern. As a well-recognized human carcinogen, its carcinogenic mechanisms are still poorly understood. Cadmium has long been considered a non-genotoxic carcinogen and thought to act through epigenetic mechanisms. In the present study, we tested the effects of long-term low-dose cadmium exposure on DNA methylation in human embryo lung fibroblast (HLF) cells. After 2 months of exposure to 0-1.5 micromol/L cadmium, both the level of genomic DNA methylation and the enzyme activity of DNA methyltransferases (DNMTs) were increased in a concentration-related manner. Moreover, our results showed that cadmium exposure up-regulated the mRNA levels of DNMT1, DNMT3a and DNMT3b at higher concentrations. We further tested the growth dynamics of HLF cells, and observed significantly elevated growth rates, decreased cell population of G0/G1-phase and increased cell population of S-phase at 0.9, 1.2, and 1.5 micromol/L concentrations. Our study indicated that long-term low-dose cadmium exposure could disrupt DNA methylation, which may be one of the possible underlying carcinogenic mechanisms of cadmium.
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Affiliation(s)
- Gaofeng Jiang
- Faculty of Preventive Medicine, Medical College, Wuhan University of Science and Technology, Huangjiahu Campus, Wuhan 430065, Hubei Province, People's Republic of China.
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Qu W, Ke H, Pi J, Broderick D, French JE, Webber MM, Waalkes MP. Acquisition of apoptotic resistance in cadmium-transformed human prostate epithelial cells: Bcl-2 overexpression blocks the activation of JNK signal transduction pathway. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:1094-100. [PMID: 17637928 PMCID: PMC1913575 DOI: 10.1289/ehp.10075] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 04/05/2007] [Indexed: 05/13/2023]
Abstract
BACKGROUND We have recently shown that cadmium can induce malignant transformation of the human prostate epithelial cell line (RWPE-1) and that these cadmium-transformed prostate epithelial (CTPE) cells acquire apoptotic resistance concurrently with malignant phenotype. OBJECTIVE The present study was designed to define the mechanism of acquired apoptotic resistance in CTPE cells. METHODS Various molecular events associated with apoptosis were assessed in control and CTPE cells that were obtained after 8 weeks of continuous cadmium exposure. RESULTS Compared with control, CTPE cells showed a generalized resistance to apoptosis induced by cadmium, cisplatin, or etoposide. Signal-regulated mitogen-activated protein kinases, extracellular signal-regulated kinases 1 and 2, c-Jun N-terminal kinases (JNK1 and JNK2), and p38 were phosphorylated in a cadmium concentration-dependent fashion in CTPE and control cells. However, phosphorylated JNK1/2 levels and JNK kinase activity were much lower in CTPE cells. The pro-apoptotic gene Bax showed lower transcript and protein levels, whereas the anti-apoptotic gene Bcl-2 showed higher levels in CTPE cells. The ratio of Bcl-2/Bax, a key determinant in apoptotic commitment, increased more than 4-fold in CTPE cells. In Bcl-2-transfected PT-67 cells, phosphorylated JNK1/2 levels were much lower after apoptogenic stimulus, and apoptosis induced by cadmium or etoposide was reduced compared with control. Mutation of tyrosine to serine at the 21st amino acid of the Bcl-2 protein BH4 domain resulted in a loss both of suppression of JNK1/2 phosphorylation and its anti-apoptotic function. CONCLUSIONS CTPE cells become resistant to apoptosis during malignant transformation, and disruption of the JNK pathway and Bcl-2 overexpression play important roles in this resistance. Bcl-2 BH4 domain is required for modulating JNK phosphorylation and anti-apoptotic function.
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Affiliation(s)
- Wei Qu
- Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences and
| | - Hengning Ke
- Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
| | - Jingbo Pi
- Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences and
| | - Daniel Broderick
- Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences and
| | - John E. French
- Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
| | - Mukta M. Webber
- Departments of Zoology and Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Michael P. Waalkes
- Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences and
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Cao XJ, Chen R, Li AP, Zhou JW. JWA gene is involved in cadmium-induced growth inhibition and apoptosis in HEK-293T cells. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2007; 70:931-7. [PMID: 17479408 DOI: 10.1080/15287390701290212] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Cadmium (Cd) is widely dispersed in the environment due to occupational and personal (cigarette) emissions. Exposure of human embryonic kidney 293T (HEK-293T) cells to CdCl2 resulted in growth inhibition and apoptosis. Our previous studies demonstrated that JWA, a novel retinoic acid-inducible and cytoskeleton-associated gene, is a potential environmental-responsive gene with increased expression attributed to oxidative and heat-shock stresses. In the present study, JWA was also found to be responsive to Cd exposure. After treatment with 20 microM CdCl2 for 12 h, the expression level of JWA was increased with accompanied growth inhibition and apoptosis. In addition, knock-down JWA protein expression by using transient transfecting of HEK-293T cells with antisense JWA express vector showed a protective effect against Cd-induced apoptosis. To determine whether the upregulation of JWA by Cd involved regulation by transcriptional mechanisms, further reporter gene assays were employed, which demonstrated a marked increase in JWA promoter activity. In addition, elevated intracellular levels of ROS components (O2-* and H2O2) and activation of JNK, ERK, and MAPK were found with corresponding upregulation of JWA protein expression. These results suggest that Cd-induced growth inhibition and apoptosis may involve ROS generation and subsequent affect on MAPK signal pathway. JWA responsiveness to CdCl2 might be through both transcriptional and posttranslational mechanisms.
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Affiliation(s)
- Xing-Jiang Cao
- Department of Molecular Cell Biology and Toxicology, School of Public Health, Nanjing Medical University, Nanjing, People's Republic of China
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Cox LAT. Quantifying potential health impacts of cadmium in cigarettes on smoker risk of lung cancer: a portfolio-of-mechanisms approach. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2006; 26:1581-99. [PMID: 17184399 DOI: 10.1111/j.1539-6924.2006.00848.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
This article introduces an approach to estimating the uncertain potential effects on lung cancer risk of removing a particular constituent, cadmium (Cd), from cigarette smoke, given the useful but incomplete scientific information available about its modes of action. The approach considers normal cell proliferation; DNA repair inhibition in normal cells affected by initiating events; proliferation, promotion, and progression of initiated cells; and death or sparing of initiated and malignant cells as they are further transformed to become fully tumorigenic. Rather than estimating unmeasured model parameters by curve fitting to epidemiological or animal experimental tumor data, we attempt rough estimates of parameters based on their biological interpretations and comparison to corresponding genetic polymorphism data. The resulting parameter estimates are admittedly uncertain and approximate, but they suggest a portfolio approach to estimating impacts of removing Cd that gives usefully robust conclusions. This approach views Cd as creating a portfolio of uncertain health impacts that can be expressed as biologically independent relative risk factors having clear mechanistic interpretations. Because Cd can act through many distinct biological mechanisms, it appears likely (subjective probability greater than 40%) that removing Cd from cigarette smoke would reduce smoker risks of lung cancer by at least 10%, although it is possible (consistent with what is known) that the true effect could be much larger or smaller. Conservative estimates and assumptions made in this calculation suggest that the true impact could be greater for some smokers. This conclusion appears to be robust to many scientific uncertainties about Cd and smoking effects.
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Kim J, Sharma RP. Cadmium-induced apoptosis in murine macrophages is antagonized by antioxidants and caspase inhibitors. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2006; 69:1181-201. [PMID: 16728380 DOI: 10.1080/15287390600631144] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Cadmium is a toxic heavy metal that accumulates in the environment and is commonly found in cigarette smoke and industrial effluents. This study was designed to determine the role of reactive oxygen species (ROS) generation, and its antagonism by antioxidants, in cadmium-mediated cell signaling and apoptosis in murine macrophage cultures. Cadmium-generated ROS production was observed in J774A.1 cells at 6 h, reverting to control levels at 16 and 24 h. The ROS production was concentration related between 20 and 500 microM cadmium. Activation of caspase-3 was observed at 8 h and DNA fragmentation at 16 h in the presence of 20 microM cadmium, suggesting that caspase-3 activation is a prior step to DNA fragmentation in cadmium-induced apoptosis. Inhibitors of caspase-3, -8, -9, and a general caspase inhibitor suppressed cadmium-induced caspase-3 activation and apoptosis indicating the importance of caspase-3 in cadmium-induced toxicity in these cells. Protection against the oxidative stress with N-acetylcysteine (NAC) and silymarin (an antioxidant flavonoid) blocked cadmium-induced apoptosis. Pretreatment of cells with NAC and silymarin prevented cadmium-induced cell injury, including growth arrest, mitochondrial impairment, and necrosis, and reduced the cadmium-elevated intracellular calcium ([Ca2+]i), suggesting that the oxidative stress is a source of increased [Ca2+]i. NAC inhibited cadmium-induced activation of mitogen-activated protein kinases, the c-Jun NH2-terminal protein kinase (JNK) and extracellular signal-regulated kinase (ERK). However, silymarin provided only a partial protection for JNK activation, and only at the low concentration did it inhibit cadmium-induced ERK activation. Inhibition of caspase-3 protected oxidative stress produced by cadmium, suggesting that the activation of caspase-3 also contributes to generation of reactive oxygen species (ROS). Results emphasized the role of ROS, Ca2+ and mitogen-activated protein kinases in cadmium-induced cytotoxicity in murine macrophages.
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Affiliation(s)
- Jiyoung Kim
- Program in Toxicology, Department of Physiology and Pharmacology, College of Veterinary Medicine, The University of Georgia, Athens, Georgia 30602-7389, USA
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Croute F, Beau B, Murat JC, Vincent C, Komatsu H, Obata F, Soleilhavoup JP. Expression of stress-related genes in a cadmium-resistant A549 human cell line. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2005; 68:703-18. [PMID: 16020198 DOI: 10.1080/15287390590925447] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
This study was designed to explain the basis for Cd-acquired tolerance of A549 cells cultured in the presence of Cd. Thirty-day exposure of cultured human pneumocytes (A549 cell line) to 10 microM Cd was previously found to induce an acquired resistance persisting over several weeks of culture. Moreover, these Cd-resistant cells (R-cells) were found to proliferate faster than controls. No difference was found between R-cells and control cells (S-cells) concerning the basal and Cd-induced level of metallothioneins expression. However, after exposure to Cd, cell glutathione levels were unchanged in R-cells while they were either increased (at 10 microM Cd) or decreased (at 25 microM Cd) in S-cells. cDNA array analysis showed that genes encoding for (GPx1) glutathione peroxidase, glutathione reductase, catalase, and superoxide dismutase were similarly expressed in R- and S-cells, whereas the gene of (GPx2) glutathione peroxidase was overexpressed in R-cells. Most genes encoding stress proteins were similarly expressed, except for HSP27 and GRP94 genes, which were respectively under- (ratio 0.5 +/- 0.1) and over- (1.8 +/- 0.5) expressed in R-cells. Acute exposure to Cd was found to trigger the upregulation of genes encoding the chaperone proteins HSP90A, HSP27, HSP40, GRP78, HSP72, and HO-1 in S-cells. In R-cells, only HO-1 and HSP72 were overexpressed but at a lower level. This suggests that the Cd-related adverse conditions, leading to protein misfolding, are lowered in R-cells. It is likely that the upregulation of GPx2 in R-cells leads to a higher antioxidant defense in these cells.
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Affiliation(s)
- Françoise Croute
- Laboratoire de Biologie Cellulaire et Pollution, Faculté de Médecine Toulouse-Purpan, Toulouse, France.
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Qu W, Diwan BA, Reece JM, Bortner CD, Pi J, Liu J, Waalkes MP. Cadmium-induced malignant transformation in rat liver cells: Role of aberrant oncogene expression and minimal role of oxidative stress. Int J Cancer 2005; 114:346-55. [PMID: 15551354 DOI: 10.1002/ijc.20736] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Our study examined the role of oxidative stress and aberrant gene expression in malignant transformation induced by chronic, low-level cadmium exposure in non-tumorigenic rat liver epithelial cell line, TRL 1215. Cells were cultured in 1.0 microM cadmium (as CdCl(2)) for up to 28 weeks and compared to passage-matched control cells. The level of cadmium used for transformation produced no evidence of increased superoxide (O(2) (-*.)) or hydrogen peroxide (H(2)O(2)) levels in the early stages of exposure (</=24 hr). The chronic cadmium exposed liver epithelial cells (CCE-LE) were hyperproliferative with a growth rate about 3-fold higher than control cells. CCE-LE cells produced highly aggressive tumors upon inoculation into mice confirming malignant transformation. Analysis of cellular reactive oxygen species (ROS) showed that CCE-LE cells possessed markedly lower basal levels of intracellular O(2) (-*.)and H(2)O(2) and were very tolerant to high-dose (50 microM) cadmium-induced ROS. Time course studies showed the production of ROS by high-dose cadmium was abolished well in advance of malignant transformation. In contrast, marked overexpression of the oncogenes c-myc and c-jun occurred in transformed CCE-LE cells as evidenced by up to 10-fold increases in both transcript and protein. A significant increase in DNA-binding activity of the transcription factors AP-1 and NF-kappaB occurred in CCE-LE cells. Increases in oncogene expression and transcription factor activity occurred concurrently with malignant transformation. Thus, cadmium-induced ROS occurs as an early, high-dose event but is abolished well in advance of malignant transformation. Low-level chronic cadmium triggers oncogene overexpression possibly by altering critical transcription factor activity. Such changes in cellular gene expression likely culminate in the loss of growth control and cadmium-induced neoplastic transformation in CCE-LE cells, whereas generation of ROS by cadmium seemed to play a minimal role in this transformation.
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Affiliation(s)
- Wei Qu
- Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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