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Zhu D, Zheng W, Chang H, Xie H. A theoretical study on the p Ka values of selenium compounds in aqueous solution. NEW J CHEM 2020. [DOI: 10.1039/d0nj01124j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The pKa values of different kinds of selenium compounds (R-SeH) were investigated by using the ωB97XD method with a SMD model.
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Affiliation(s)
- Danfeng Zhu
- College of Chemistry and Chemical Engineering
- Shanghai University of Engineering Science
- Shanghai 201620
- China
| | - Wenrui Zheng
- College of Chemistry and Chemical Engineering
- Shanghai University of Engineering Science
- Shanghai 201620
- China
| | - Huifang Chang
- College of Chemistry and Chemical Engineering
- Shanghai University of Engineering Science
- Shanghai 201620
- China
| | - Hongyun Xie
- College of Chemistry and Chemical Engineering
- Shanghai University of Engineering Science
- Shanghai 201620
- China
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2
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Nasim MJ, Witek K, Kincses A, Abdin AY, Żesławska E, Marć MA, Gajdács M, Spengler G, Nitek W, Latacz G, Karczewska E, Kieć-Kononowicz K, Handzlik J, Jacob C. Pronounced activity of aromatic selenocyanates against multidrug resistant ESKAPE bacteria. NEW J CHEM 2019. [DOI: 10.1039/c9nj00563c] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Selenocyanates demonstrate pronounced activity against bacteria of the ESKAPE family, yeast and nematodes with limited cytotoxicity against human cells.
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Banerjee K, Padmavathi G, Bhattacherjee D, Saha S, Kunnumakkara AB, Bhabak KP. Potent anti-proliferative activities of organochalcogenocyanates towards breast cancer. Org Biomol Chem 2018; 16:8769-8782. [DOI: 10.1039/c8ob01891j] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The synthesis of benzylic and mesitylenic organochalcogenocyanates has been described and the compounds have been studied for their anti-proliferative activities in breast cancer cells (MDA-MB-231, MCF-7 and T-47D).
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Affiliation(s)
- Kaustav Banerjee
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Ganesan Padmavathi
- Cancer Biology Laboratory & DBT-AIST International Laboratory for Advanced Biomedicine (DAILAB)
- Department of Biosciences and Bioengineering
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Debojit Bhattacherjee
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
- Centre for the Environment
| | - Suchismita Saha
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Ajaikumar B. Kunnumakkara
- Cancer Biology Laboratory & DBT-AIST International Laboratory for Advanced Biomedicine (DAILAB)
- Department of Biosciences and Bioengineering
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Krishna P. Bhabak
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
- Centre for the Environment
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5
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Zheng W, Benkessou F, Twelkmeyer B, Wang S, Ginman T, Ottosson H, Abedi-Valugerdi M, Subirana MA, Zhao Y, Hassan M. Rapid and Robust Quantification of p-Xyleneselenocyanate in Plasma via Derivatization. Anal Chem 2017. [DOI: 10.1021/acs.analchem.7b01426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Wenyi Zheng
- Experimental
Cancer Medicine, Clinical Research Center, Department of Laboratory
Medicine, Karolinska Institutet, Huddinge, 141 86 Stockholm, Sweden
| | - Fadwa Benkessou
- Experimental
Cancer Medicine, Clinical Research Center, Department of Laboratory
Medicine, Karolinska Institutet, Huddinge, 141 86 Stockholm, Sweden
| | - Brigitte Twelkmeyer
- Department
of Anesthesiology and Intensive Care, CLINTEC, Karolinska Institutet and Karolinska University Hospital, Huddinge, 141 86 Stockholm, Sweden
| | - Siyao Wang
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Tobias Ginman
- Sprint Bioscience, Huddinge, 141 86 Stockholm, Sweden
| | - Håkan Ottosson
- Department
of Biosciences and Nutrition, Karolinska Institutet, Huddinge, 141 86 Stockholm, Sweden
| | - Manuchehr Abedi-Valugerdi
- Experimental
Cancer Medicine, Clinical Research Center, Department of Laboratory
Medicine, Karolinska Institutet, Huddinge, 141 86 Stockholm, Sweden
| | - Maria Angels Subirana
- Universitat Autònoma de Barcelona, Department
of Chemistry, Centre GTS, 08193 Bellaterra Barcelona, Spain
| | - Ying Zhao
- Experimental
Cancer Medicine, Clinical Research Center, Department of Laboratory
Medicine, Karolinska Institutet, Huddinge, 141 86 Stockholm, Sweden
- ECM,
Clinical Research Center, Karolinska University Hospital, Huddinge, 141 86 Stockholm, Sweden
| | - Moustapha Hassan
- Experimental
Cancer Medicine, Clinical Research Center, Department of Laboratory
Medicine, Karolinska Institutet, Huddinge, 141 86 Stockholm, Sweden
- ECM,
Clinical Research Center, Karolinska University Hospital, Huddinge, 141 86 Stockholm, Sweden
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6
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Fang M, Guo WR, Park Y, Kang HG, Zarbl H. Enhancement of NAD⁺-dependent SIRT1 deacetylase activity by methylselenocysteine resets the circadian clock in carcinogen-treated mammary epithelial cells. Oncotarget 2016; 6:42879-91. [PMID: 26544624 PMCID: PMC4767478 DOI: 10.18632/oncotarget.6002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/13/2015] [Indexed: 12/29/2022] Open
Abstract
We previously reported that dietary methylselenocysteine (MSC) inhibits N-methyl-N-nitrosourea (NMU)-induced mammary tumorigenesis by resetting circadian gene expression disrupted by the carcinogen at the early stage of tumorigenesis. To investigate the underlying mechanism, we developed a circadian reporter system comprised of human mammary epithelial cells with a luciferase reporter driven by the promoter of human PERIOD 2 (PER2), a core circadian gene. In this in vitro model, NMU disrupted cellular circadian rhythm in a pattern similar to that observed with SIRT1-specific inhibitors; in contrast, MSC restored the circadian rhythms disrupted by NMU and protected against SIRT1 inhibitors. Moreover, NMU inhibited intracellular NAD+/NADH ratio and reduced NAD+-dependent SIRT1 activity in a dose-dependent manner, while MSC restored NAD+/NADH and SIRT1 activity in the NMU-treated cells, indicating that the NAD+-SIRT1 pathway was targeted by NMU and MSC. In rat mammary tissue, a carcinogenic dose of NMU also disrupted NAD+/NADH oscillations and decreased SIRT1 activity; dietary MSC restored NAD+/NADH oscillations and increased SIRT1 activity in the mammary glands of NMU-treated rats. MSC-induced SIRT1 activity was correlated with decreased acetylation of BMAL1 and increased acetylation of histone 3 lysine 9 at the Per2 promoter E-Box in mammary tissue. Changes in SIRT1 activity were temporally correlated with loss or restoration of rhythmic Per2 mRNA expression in NMU-treated or MSC-rescued rat mammary glands, respectively. Together with our previous findings, these results suggest that enhancement of NAD+-dependent SIRT1 activity contributes to the chemopreventive efficacy of MSC by restoring epigenetic regulation of circadian gene expression at early stages of mammary tumorigenesis.
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Affiliation(s)
- Mingzhu Fang
- Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,School of Public Health, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,Environmental and Occupational Health Sciences Institute, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,NIEHS Center for Environmental Exposures and Disease, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Wei-Ren Guo
- Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Youngil Park
- Veterinary Drugs & Biologics Division, Animal and Plant Quarantine Agency, Anyang 430-757, Republic of Korea
| | - Hwan-Goo Kang
- Veterinary Drugs & Biologics Division, Animal and Plant Quarantine Agency, Anyang 430-757, Republic of Korea
| | - Helmut Zarbl
- Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,School of Public Health, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,Environmental and Occupational Health Sciences Institute, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,NIEHS Center for Environmental Exposures and Disease, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.,Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
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7
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Gopalakrishna R, Gundimeda U, Zhou S, Zung K, Forell K, Holmgren A. Imbalance in Protein Thiol Redox Regulation and Cancer-Preventive Efficacy of Selenium. REACTIVE OXYGEN SPECIES (APEX, N.C.) 2016; 2:272-289. [PMID: 29795790 DOI: 10.20455/ros.2016.851] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although several experimental studies showed cancer-preventive efficacy of supplemental dietary selenium, human clinical trials questioned this efficacy. Identifying its molecular targets and mechanism is important in understanding this discrepancy. Methylselenol, the active metabolite of selenium, reacts with lipid hydroperoxides bound to protein kinase C (PKC) and is oxidized to methylseleninic acid (MSA). This locally generated MSA selectively inactivates PKC by oxidizing its critical cysteine sulfhydryls. The peroxidatic redox cycle occurring in this process may explain how extremely low concentrations of selenium catalytically modify specific membrane-bound proteins compartmentally separated from glutathione and selectively induce cytotoxicity in promoting cells. Mammalian thioredoxin reductase (TR) is itself a selenoenzyme with a catalytic selenocysteine residue. Together with thioredoxin (Trx), it catalyzes reduction of selenite and selenocystine by NADPH generating selenide which in the presence of oxygen redox cycles producing reactive oxygen species. Trx binds with high affinity to PKC and reverses PKC inactivation. Therefore, established tumor cells overexpressing TR and Trx may escape the cancer-preventive actions of selenium. This suggests that in some cases, certain selenoproteins may counteract selenometabolite actions. Lower concentrations of selenium readily inactivate antiapoptotic PKC isoenzymes e and a which have a cluster of vicinal thiols, thereby inducing apoptosis. Higher concentrations of selenium also inactivate proapoptotic enzymes such as proteolytically activated PKCd fragment, holo-PKCz, caspase-3, and c-Jun N-terminal kinase, which all have a limited number of critical cysteine residues and make tumor cells resistant to selenium-induced apoptosis. This may explain the intriguing U-shaped curve that is seen with dietary selenium intake and the extent of cancer prevention.
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Affiliation(s)
- Rayudu Gopalakrishna
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Usha Gundimeda
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Sarah Zhou
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Kristen Zung
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Kaitlyn Forell
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Arne Holmgren
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 77 Stockholm, Sweden
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8
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Shimada T, Murayama N, Tanaka K, Takenaka S, Guengerich FP, Yamazaki H, Komori M. Spectral modification and catalytic inhibition of human cytochromes P450 1A1, 1A2, 1B1, 2A6, and 2A13 by four chemopreventive organoselenium compounds. Chem Res Toxicol 2011; 24:1327-37. [PMID: 21732699 DOI: 10.1021/tx200218u] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Several organoselenium compounds including benzyl selenocyanate (BSC), 1,2-phenylenebis(methylene)selenocyanate (o-XSC), 1,3-phenylenebis(methylene)selenocyanate (m-XSC), and 1,4-phenylenebis(methylene)selenocyanate (p-XSC) have been shown to prevent cancers caused by polycyclic aromatic hydrocarbons (PAHs) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in experimental animals; these chemical carcinogens are activated by human P450 1 and 2A family enzymes, respectively, to carcinogenic metabolites. In this study, we examined whether these selenium compounds interact with and inhibit human P450 1 and 2A enzymes in vitro. Four organoselenium compounds induced reverse Type I binding spectra with P450 1A1, 1A2, and 1B1 and Type I binding spectra with P450 2A6 and 2A13. The spectral dissociation constants (K(s)) for the interaction of P450 1B1 with these chemicals were 3.6-5.7 μM; the values were lower than those with seen with P450 1A1 (19-30 μM) or 1A2 (6.3-13 μM). The K(s) values for Type I binding of P450 2A13 with m-XSC and BSC were both 0.20 μM; the values were very low compared to those for the interaction of P450 2A6 with m-XSC (5.7 μM) and BSC (2.0 μM). Four selenium compounds directly inhibited 7-ethoxyresorufin O-deethylation activities catalyzed by P450 1A1, 1A2, and 1B1 with IC(50) values <1.0 μM, except for the inhibition of P450 1A2 by BSC (1.3 μM). Coumarin 7-hydroxylation activities of P450 2A13 were more inhibited by four selenium compounds than those of P450 2A6, with IC(50) values of 0.22-1.4 μM for P450 2A13 and 2.4-6.2 μM for P450 2A6. Molecular docking studies of the interaction of four organoselenium compounds with human P450 enzymes suggest that these chemicals can be docked into the active sites of these human P450 enzymes and that the sites of the selenocyanate functional groups of these chemicals differ between the P450 1 and 2A family enzymes.
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Affiliation(s)
- Tsutomu Shimada
- Laboratory of Cellular and Molecular Biology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University , 1-58 Rinku-Orai-Kita, Izumisano, Osaka 598-8531, Japan
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9
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Pinto JT, Sinha R, Papp K, Facompre ND, Desai D, El-Bayoumy K. Differential effects of naturally occurring and synthetic organoselenium compounds on biomarkers in androgen responsive and androgen independent human prostate carcinoma cells. Int J Cancer 2007; 120:1410-7. [PMID: 17205524 DOI: 10.1002/ijc.22500] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Epidemiological studies and clinical trials show that selenium supplementation results in reduction of prostate cancer incidence; however, the form of selenium and mechanisms underlying protection remain largely unknown. Toward this end, we compared the effects of naturally occurring selenomethionine (SM) and Se-methylselenocysteine (MSC) and synthetic 1,4-phenylenebis(methylene)selenocyanate (p-XSC) and p-xylylbis(methylselenide) p-XMS) organoselenium compounds in androgen responsive (AR) LNCaP and its androgen independent clone (AI) LNCaP C4-2 human prostate carcinoma cells on cell growth, secretion of prostate specific antigen (PSA), intracellular redox status and genomic profiles with emphasis on identifying redox sensitive genes. Both p-XSC and p-XMS reduced cell number and total protein concentration compared to control-treated AR and AI cells, while SM and MSC exhibited no effect on growth of AR and AI cells. SM, p-XSC and p-XMS but not MSC inhibited levels of secreted PSA in AR cells. SM, MSC and p-XMS increased glutathione (GSH) levels in AI LNCaP cells. By contrast, in both cell types, only p-XSC significantly decreased GSH concentrations to <50% of control suggesting either an increase in intracellular oxidative stress or a change in GSH/GSSG ratio. On the basis of RT-PCR analysis, SM and p-XSC increased p53 gene expression by 2-fold in AR cells but not in AI cells and only SM enhanced epidermal growth factor receptor in AR cells. Depending on the structure, organoselenium compounds exhibit differential effects on growth, PSA secretion, oxidative stress and selective gene responses in human prostate cancer cells and suggest the potential of developing novel organoselenium compounds as chemopreventive agents in models of human prostate cancer.
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Affiliation(s)
- John T Pinto
- Laboratory of Molecular Neurobiology, Cornell-Burke Medical Research Institute, White Plains, NY 10605, USA.
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10
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El-Bayoumy K, Sinha R, Pinto JT, Rivlin RS. Cancer chemoprevention by garlic and garlic-containing sulfur and selenium compounds. J Nutr 2006; 136:864S-869S. [PMID: 16484582 DOI: 10.1093/jn/136.3.864s] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
As early as 1550 B.C., Egyptians realized the benefits of garlic as a remedy for a variety of diseases. Many epidemiological studies support the protective role of garlic and related allium foods against the development of certain human cancers. Natural garlic and garlic cultivated with selenium fertilization have been shown in laboratory animals to have protective roles in cancer prevention. Certain organoselenium compounds and their sulfur analogs have been identified in plants. Organoselenium compounds synthesized in our laboratory were compared with their sulfur analogs for chemopreventive efficacy. Diallyl selenide was at least 300-fold more effective than diallyl sulfide in protecting against 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary adenocarcinomas in rats. In addition, benzyl selenocyanate inhibited the development of DMBA-induced mammary adenocarcinomas and azoxymethane-induced colon cancer in rats and benzo[a]pyrene-induced forestomach tumors in mice. The sulfur analog, benzyl thiocyanate, had no effect under the same experimental conditions. Furthermore, we showed that 1,4-phenylenebis(methylene)selenocyanate, but not its sulfur analog, significantly inhibited DMBA-DNA adduct formation and suppressed DMBA-induced mammary carcinogenesis. Collectively, these results indicate that structurally distinctive organoselenium compounds are superior to their corresponding sulfur analogs in cancer chemoprevention. Additionally, synthetic aromatic selenocyanates are more effective cancer chemopreventive agents than the naturally occurring selenoamino acids. Because plants are capable of utilizing selenium in a manner similar to that in sulfur assimilation pathways, future studies should aim at determining whether, under appropriate conditions, these potent cancer chemopreventive synthetic selenium compounds can be synthesized by garlic and related allium foods.
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Affiliation(s)
- Karam El-Bayoumy
- Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA.
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11
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Sohn OS, Desai DH, Das A, Rodriguez JG, Amin SG, El-Bayoumy K. Comparative excretion and tissue distribution of selenium in mice and rats following treatment with the chemopreventive agent 1,4-phenylenebis(methylene)selenocyanate. Chem Biol Interact 2005; 151:193-202. [PMID: 15733540 DOI: 10.1016/j.cbi.2004.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2004] [Indexed: 11/17/2022]
Abstract
In a previous preliminary investigation, we reported on the excretion, tissue disposition and metabolism of the chemopreventive agent 1,4-phenylenebis(methylene)selenocyanate (p-XSC) in the rat, but similar studies in the mouse have not been explored. Following the oral administration of p-XSC (50 micromol/kg body weight), selenium excretion in feces was comparable to that in urine in mice, but in rats, feces was the major route of excretion. Tetraselenocyclophane (TSC) was the major metabolite detected in mouse and rat feces. In both species, levels of selenium in exhaled air were negligible. At termination, in the mouse, the stomach had the highest selenium content followed by liver and blood, but lung and kidney contained negligible levels of selenium; in the rat, the selenium level in liver was the highest followed by kidney, stomach, blood and lung. The identification of TSC as a fecal metabolite in both species let us to postulate the following metabolic pathway: p-XSC-->glutathione conjugate (p-XSeSG)-->a selenol (p-XSeH)-->TSC. Since the glutathione conjugate appears to be the proximal precursor for the selenol metabolite that may be an important intermediate in cancer chemoprevention, we report for the first time the synthesis of p-XSeSG and its other potential metabolites, namely the cysteine- and N-acetylcysteine-conjugates of p-XSC. HPLC analysis of the urine and bile showed a few metabolites of p-XSC; none of which eluted with the synthetic standards described above. When we examined the conversion of p-XSC and p-XSeSG in vitro using rat cecal microflora, TSC was formed from p-XSeSG but not from p-XSC. The formation of TSC from p-XSC in vivo but not in vitro suggests that p-XSC needs to be metabolized to p-XSeSG or an intermediate derived from its further metabolism. Thus, p-XSeSG was given orally to rats and the results showed that the pattern of selenium excretion after p-XSeSG treatment was similar to that of p-XSC; TSC was also identified as a fecal metabolite of p-XSeSG. It may be that the conversion of p-XSeSG to TSC is too facile, or the mere conjugation of p-XSC with glutathione does not occur in rats and mice.
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Affiliation(s)
- Ock Soon Sohn
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033-0850, USA
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12
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El-Bayoumy K, Sinha R. Mechanisms of mammary cancer chemoprevention by organoselenium compounds. Mutat Res 2004; 551:181-97. [PMID: 15225592 DOI: 10.1016/j.mrfmmm.2004.02.023] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2003] [Revised: 02/23/2004] [Accepted: 02/23/2004] [Indexed: 01/02/2023]
Abstract
Searching for optimal diets and for naturally occurring agents in routinely consumed foods that may inhibit cancer development, although challenging, constitutes a valuable and plausible approach to finding ways to control and prevent cancer. To date, the use of the micronutrient selenium in human clinical trials is limited but the outcome of these investigations indicates that selenium is one of the most promising agents. Data presented in this mini-review indicate that the dose and the form (structure) in which selenium is used are the most critical determinants of success in future clinical trials. The focus of this mini-review is on the mechanisms of mammary cancer chemoprevention by organoselenium compounds. Among the naturally occurring organoselenium compounds, Se-Methylselenocysteine is more efficacious than the most extensively studied forms, such as selenomethionine. However, we showed that synthetic organoselenium compounds can be tailored to achieve greater chemopreventive efficacy with minimal side effects by structural modifications; it is evident that synthetic agents are superior to the inorganic selenite, naturally occurring selenium compounds and their sulfur-containing analogs. We have demonstrated that 1,4-phenylenebis (methylene) selenocyanate (p-XSC) and its putative metabolite glutathione conjugate (p-XSeSG) are highly promising agents in the chemoprevention of mammary carcinogenesis in the 7,12-dimethylbenz[a]anthracene (DMBA)-rat mammary tumor model system. Both compounds inhibit the initiation phase of carcinogenesis by inhibiting DMBA-DNA adduct formation in the target organ in vivo. cDNA microarray analysis indicates that both selenium compounds alter genes in a manner that leads to inhibition of cell proliferation and induction of apoptosis; modulation of apoptosis and cell proliferation can account for chemoprevention during the post-initiation phase of mammary carcinogenesis. Using a rat mammary cancer cell line, we compared p-XSC and p-XSeSG as inhibitors of cell proliferation; depending on the selenium dose and time point selected, p-XSC was comparable to or better than p-XSeSG. Collectively, the results described here, suggest that the molecular targets modulated by organoselenium compounds are highly useful indicators of success in clinical cancer chemoprevention trials.
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Affiliation(s)
- Karam El-Bayoumy
- Institute for Cancer Prevention, American Health Foundation Cancer Center, 1 Dana Road, Valhalla, NY 10595, USA.
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13
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El-Bayoumy K, Das A, Boyiri T, Desai D, Sinha R, Pittman B, Amin S. Comparative action of 1,4-phenylenebis(methylene)selenocyanate and its metabolites against 7,12-dimethylbenz[a]anthracene-DNA adduct formation in the rat and cell proliferation in rat mammary tumor cells. Chem Biol Interact 2003; 146:179-90. [PMID: 14597131 DOI: 10.1016/j.cbi.2003.08.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
1,4-phenylenebis(methylene)selenocyanate (p-XSC) inhibits 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinogenesis and DMBA-DNA binding in the rat mammary gland. Tetraselenocyclophane (TSC) was identified in rat feces as a metabolite of p-XSC. This led us to postulate the metabolic pathway: p-XSC-->glutathione conjugate (p-XSeSG)-->aromatic selenol (p-XSeH)-->TSC. Whether p-XSC or one of its metabolites is responsible for cancer prevention is the focus of this study. We utilized the DMBA-DNA binding assay with p-XSC as a positive control to evaluate the chemopreventive potential of p-XSC metabolites at dietary selenium levels of 10 ppm. Rats were fed AIN-76A diet supplemented with various selenium compounds for 1 week prior to the oral administration of a single dose of [3H]DMBA (5 mg per rat, specific activity 51.3 mCi/mmol). The rats were sacrificed 24 h later and DNA was isolated from the mammary fat pads. Relative levels of total binding were: [pmol/mg DNA, mean +/- S.D., n=6]; DMBA [7.2 +/- 1.6]; DMBA+p-XSC [3.5 +/- 2.7]; DMBA+p-XSeSG [2.2 +/- 1.1]; DMBA+TSC [5.6 +/- 2.9]. All selenium compounds, except TSC, significantly inhibited DMBA-DNA adduct formation; however, the difference between p-XSC and p-XSeSG was not statistically significant. The inhibition of total binding was attributed to a reduction in the formation of the three major adducts derived from bay-region diol epoxides of DMBA. On the basis of their chromatographic characteristics, these were identified as anti-diol-epoxide:deoxyguanosine, syn-diol-epoxide:deoxyadenosine, and anti-diol-epoxide:deoxyadenosine. Our results suggest that p-XSeSG, but not TSC, is the likely inhibitor of mammary cancer. Selenium levels measured by atomic absorption spectroscopy in the target organ (mammary fat pads) and in plasma following the dietary administration of selenium compounds were in the order of p-XSeSG congruent with p-XSC>TSC. These results appear to be consistent with their order of inhibitory effects on total DMBA-DNA binding. Further in vitro studies of the effect of selenium compounds on cell proliferation suggest that, depending on the dose and time point selected, p-XSC is comparable to or better than p-XSeSG; but both are more effective than TSC. Collectively, our in vivo and in vitro results indicate that p-XSC and its conjugate are better candidates than TSC for future studies on mammary cancer chemoprevention.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/analogs & derivatives
- 9,10-Dimethyl-1,2-benzanthracene/metabolism
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Adenocarcinoma/drug therapy
- Adenocarcinoma/pathology
- Animals
- Anticarcinogenic Agents/pharmacology
- Carcinogens/metabolism
- Carcinogens/toxicity
- Cell Division/drug effects
- DNA Adducts/drug effects
- DNA Damage
- Female
- Mammary Neoplasms, Animal/drug therapy
- Mammary Neoplasms, Animal/pathology
- Organoselenium Compounds/metabolism
- Organoselenium Compounds/pharmacology
- Rats
- Rats, Sprague-Dawley
- Specific Pathogen-Free Organisms
- Tumor Cells, Cultured
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Affiliation(s)
- Karam El-Bayoumy
- American Health Foundation Cancer Center, Institute for Cancer Prevention, 1 Dana Road, Valhalla, NY 10595, USA.
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Gopalakrishna R, Gundimeda U. Antioxidant regulation of protein kinase C in cancer prevention. J Nutr 2002; 132:3819S-3823S. [PMID: 12468631 DOI: 10.1093/jn/132.12.3819s] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Besides scavenging free radicals, antioxidants inhibit signaling enzymes such as protein kinase C (PKC) that play a crucial role in tumor promotion. By having different oxidation susceptible regions, PKC can respond to both oxidant tumor promoters and cancer-preventive antioxidants to elicit opposite cellular responses. Oxidant tumor promoters activate PKC by reacting with zinc-thiolates present within the regulatory domain. In contrast, the oxidized forms of some cancer-preventive agents, such as polyphenolics (ellagic acid, 4-hydroxytamoxifen and curcumin) and selenocompounds, can inactivate PKC by oxidizing the vicinal thiols present within the catalytic domain. This brings an efficient counteractive mechanism to block the signal transduction induced by tumor promoters at the first step itself. Because prostate cancer prevention clinical trials in large human population are under way, we have focused more on understanding the cancer-preventive mechanism of selenium. Methylselenol, the postulated cancer-preventive metabolite, has no direct effect on PKC activity. However, methylseleninic acid, locally generated by the reaction of membrane methylselenol with PKC-bound tumor-promoting fatty acid hydroperoxides, selectively inactivates PKC. This mechanism clarifies how the volatile methylselenol that is present in a low concentration induces the inactivation of PKC selectively in the promoting precancer cells. Selenoprotein thioredoxin reductase reverses selenium-induced inactivation of PKC, suggesting that selenoproteins may serve as a safeguard against the toxicity induced by selenometabolites. Moreover, this also explains how a resistance to selenium develops in advanced malignant cells. The redox-mediated inactivation of PKC may, at least in part, be responsible for the antioxidant-induced inhibition of tumor promotion and cell growth, as well as for the induction of cell death.
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Affiliation(s)
- Rayudu Gopalakrishna
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles 90089, USA.
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el-Bayoumy K, Rao CV, Reddy BS. Multiorgan sensitivity to anticarcinogenesis by the organoselenium 1,4-phenylenebis(methylene)selenocyanate. Nutr Cancer 2002; 40:18-27. [PMID: 11799918 DOI: 10.1207/s15327914nc401_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The data in this report clearly indicate that the form (structure) in which selenium is used is the most critical determinant of success in future clinical trials. Synthetic organoselenium compounds can be tailored to achieve greater chemopreventive efficacy with minimal toxic side effects by structural modifications. We demonstrated that 1,4-phenylenebis(methylene)selenocyanate is a powerful chemopreventive agent against the development of experimental colon, mammary, lung, and oral carcinogenesis. On the basis of metabolism studies of organoselenium compounds and those reported in the literature, our working hypothesis is that aromatic selenol intermediates are important entities in cancer chemoprevention. In addition, we suggest that 1,4-phenylenebis(methylene)selenocyanate not only serves as a chemopreventive agent, but it may be valuable in preventing metastatic diseases in future studies in the clinic.
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Affiliation(s)
- K el-Bayoumy
- American Health Foundation, Valhalla, NY 10595, USA.
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16
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Jacob C, Maret W, Vallee BL. Selenium redox biochemistry of zinc-sulfur coordination sites in proteins and enzymes. Proc Natl Acad Sci U S A 1999; 96:1910-4. [PMID: 10051568 PMCID: PMC26710 DOI: 10.1073/pnas.96.5.1910] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/31/1998] [Indexed: 11/18/2022] Open
Abstract
Selenium has been increasingly recognized as an essential element in biology and medicine. Its biochemistry resembles that of sulfur, yet differs from it by virtue of both redox potentials and stabilities of its oxidation states. Selenium can substitute for the more ubiquitous sulfur of cysteine and as such plays an important role in more than a dozen selenoproteins. We have chosen to examine zinc-sulfur centers as possible targets of selenium redox biochemistry. Selenium compounds release zinc from zinc/thiolate-coordination environments, thereby affecting the cellular thiol redox state and the distribution of zinc and likely of other metal ions. Aromatic selenium compounds are excellent spectroscopic probes of the otherwise relatively unstable functional selenium groups. Zinc-coordinated thiolates, e.g., metallothionein (MT), and uncoordinated thiolates, e.g., glutathione, react with benzeneseleninic acid (oxidation state +2), benzeneselenenyl chloride (oxidation state 0) and selenocystamine (oxidation state -1). Benzeneseleninic acid and benzeneselenenyl chloride react very rapidly with MT and titrate substoichiometrically and with a 1:1 stoichiometry, respectively. Selenium compounds also catalyze the release of zinc from MT in peroxidation and thiol/disulfide-interchange reactions. The selenoenzyme glutathione peroxidase catalytically oxidizes MT and releases zinc in the presence of t-butyl hydroperoxide, suggesting that this type of redox chemistry may be employed in biology for the control of metal metabolism. Moreover, selenium compounds are likely targets for zinc/thiolate coordination centers in vivo, because the reactions are only partially suppressed by excess glutathione. This specificity and the potential to undergo catalytic reactions at low concentrations suggests that zinc release is a significant aspect of the therapeutic antioxidant actions of selenium compounds in antiinflammatory and anticarcinogenic agents.
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Affiliation(s)
- C Jacob
- Center for Biochemical and Biophysical Sciences and Medicine, Harvard Medical School, Seeley G. Mudd Building, 250 Longwood Avenue, Boston, MA 02115, USA
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