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1.
Int J Biol Macromol ; 142: 125-141, 2020 Jan 01.
Article in English | MEDLINE | ID: mdl-31521661

ABSTRACT

Understanding and elucidating the mechanism of host-pathogen interactions are the major area of interest among the Parasitologists all around the globe. Starting from the origin on mother earth parasites have searched for successful strategies to invade their respective host for the sake of survivability and eventually succeeded to manage in the unfriendly environment inside the host's body. Parasite-generated antioxidants are potent enough to combat the oxidative challenges inside the host body and within its own as well. Antioxidant enzymes are tremendously important as they are directly related to the survival of the parasites. The thiol-based antioxidant enzymes (glutathione reductase and thioredoxin reductase) have dragged much attention of the researchers to date. In this regard, among the thiol-based antioxidants, particularly the Thioredoxin reductase (TrxR), is known to be present in a number of parasitic organisms have pulled the researchers. Therefore, selective targeting of TrxR can emerge as a novel capital for developing suitable adulticidal candidate for treating filariasis and other helminth infections. This review tries to assemble the existing knowledge of the parasitic TrxR and how these can be utilized as a druggable target in cases of filariasis and other helminth infections has been discussed.


Subject(s)
Antioxidants/pharmacology , Filariasis/drug therapy , Parasitic Diseases/drug therapy , Thioredoxin-Disulfide Reductase/drug effects , Animals , Antioxidants/chemistry , Glutathione Reductase/drug effects , Helminths/drug effects , Helminths/enzymology , Humans , Oxidation-Reduction , Oxidative Stress , Parasites/drug effects , Parasites/enzymology , Substrate Specificity , Sulfhydryl Compounds , Thioredoxin-Disulfide Reductase/chemistry , Thioredoxins/pharmacology
2.
Eur J Med Chem ; 175: 269-286, 2019 Aug 01.
Article in English | MEDLINE | ID: mdl-31096151

ABSTRACT

Organometallic complexes have widely been used for the treatment of various diseases viz., malaria, arthritis, syphilis, pernicious anemia, tuberculosis and particular in cancers. Recent decades have witnessed an upsurging interest in the application of organometallic compounds to treat various phenotypes of cancers with multiple etiologies. The unique and exceptional properties of organometallic compounds, intermediate between classical inorganic and organic materials provide new insight in the progress of inorganic medicinal chemistry. Herein, we have selectively focused on various organometallic sandwich and half-sandwich complexes of ruthenium (Ru), titanium (Ti), gold (Au) and iron (Fe) exhibiting promising activity towards a panel of cancer cell lines and resistant cancer cell lines. These complexes exhibit novel mechanisms of drug action through incorporation of outer-sphere recognition of molecular targets and controlled activation features based on ligand substitution along with monometallic and heterometallic redox processes. Furthermore, they are usually found to be uncharged or neutral possessing metals in a low oxidation state, exhibit kinetic stability, relative lipophilicity and are amenable to a host of various chemical transformations. This review mainly sheds light on the successful advancement of organometallic complexes as anticancer drug aspirants in relation to their versatile structural chemistry and innovative mechanisms of action targeting nucleic acids, several enzymes viz; thioredoxin reductases (Thrx), EGFR, transferrin, cathepsin B, topoisomerases etc.


Subject(s)
Antineoplastic Agents/pharmacology , Neoplasms/drug therapy , Organometallic Compounds/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/therapeutic use , Cathepsin B/drug effects , Cell Line , Cell Line, Tumor , DNA Topoisomerases/drug effects , ErbB Receptors/drug effects , Gold/chemistry , Humans , Neoplasms/pathology , Nucleic Acids/drug effects , Organometallic Compounds/chemistry , Organometallic Compounds/therapeutic use , Ruthenium/chemistry , Thioredoxin-Disulfide Reductase/drug effects , Titanium/chemistry , Transferrin/drug effects
3.
Free Radic Biol Med ; 127: 238-247, 2018 11 01.
Article in English | MEDLINE | ID: mdl-29807162

ABSTRACT

Thioredoxin system is a ubiquitous disulfide reductase system evolutionarily conserved through all living organisms. It contains thioredoxin (Trx), thioredoxin reductase (TrxR) and NADPH. TrxR can use NADPH to reduce Trx which passes the reducing equivalent to its downstream substrates involved in various biomedical events, such as ribonucleotide reductase for deoxyribonucleotide and DNA synthesis, or peroxiredoxins for counteracting oxidative stress. Obviously, TrxR stays in the center of the system to maintain the electron flow. Mammalian TrxR contains a selenocysteine (Sec) in its active site, which is not present in the low molecular weight prokaryotic TrxRs. Due to the special property of Sec, mammalian TrxR employs a different catalytic mechanism from prokaryotic TrxRs and has a broader substrate-spectrum. On the other hand, Sec is easily targeted by electrophilic compounds which inhibits the TrxR activity and may turn TrxR into an NADPH oxidase. Ebselen, a synthetic seleno-compound containing selenazol, has been tested in several clinical studies. In mammalian cells, ebselen works as a GSH peroxidase mimic and mainly as a peroxiredoxin mimic via Trx and TrxR to scavenge hydrogen peroxide and peroxynitrite. In prokaryotic cells, ebselen is an inhibitor of TrxR and leads to elevation of reactive oxygen species (ROS). Recent studies have made use of the difference and developed ebselen as a potential antibiotic, especially in combination with silver which enables ebselen to kill multi-drug resistant Gram-negative bacteria. Collectively, Sec is important for the biological functions of mammalian TrxR and distinguishes it from prokaryotic TrxRs, therefore it is a promising drug target.


Subject(s)
Azoles/pharmacology , Cyclooxygenase Inhibitors/pharmacology , Organoselenium Compounds/pharmacology , Selenocysteine/metabolism , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Animals , Antioxidants/pharmacology , Humans , Isoindoles , Oxidative Stress/drug effects
4.
Article in English | MEDLINE | ID: mdl-27007390

ABSTRACT

The present study investigated the influence of the cigarette smoke extract (CSE) on mammalian thioredoxin reductase (TrxR) activity. TrxR is a selenoenzyme with a selenocysteine (Sec) residue exposed on the enzyme's surface. This unique Sec residue is particularly susceptible to modification by numerous types of electrophiles, leading to inactivation of TrxR and consequent cytotoxicity. Cigarette smoke contains various electrophiles, and the present study showed that CSE could inhibit intracellular TrxR through causing crosslinking and alkylation of TrxR1. TrxR inhibitory capacities of various CSEs were evaluated by using mouse-liver homogenate. Among the CSEs prepared from 18 commercial cigarette brands, TrxR inhibitory capacities of the maximum and the minimum had a 2.5-fold difference. Importantly, CSE's inhibitory capacity greatly paralleled its cytotoxic potency in all cell lines used. Compared to cytotoxic assays, which have been widely used for evaluating cigarette toxicity but are not suitable for simultaneously examining a large number of cigarette samples, the present method was simple and rapid with a high-throughput feature and thus could be used as an auxiliary means to predict the cytotoxicity of a large number of cigarette samples, making it possible to extensively screen numerous agricultural and industrial measures that potentially affect cigarette safety.


Subject(s)
Cytotoxins/metabolism , Smoke/adverse effects , Smoking/physiopathology , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Tobacco Products/adverse effects , Animals , Carcinoma, Squamous Cell , Cell Line, Tumor/drug effects , Humans , Mice , Oxidation-Reduction
5.
Biomed Res Int ; 2013: 983821, 2013.
Article in English | MEDLINE | ID: mdl-24459674

ABSTRACT

This study investigates the efficacy of diphenyl diselenide [(PhSe)2] in attenuating methylmercury- (MeHg-)induced toxicity in rats. Adult rats were treated with MeHg [5 mg/kg/day, intragastrically (i.g.)] and/ or (PhSe)2 [1 mg/kg/day, intraperitoneally (i.p.)] for 21 days. Body weight gain and motor deficits were evaluated prior to treatment, on treatment days 11 and 21. In addition, hepatic and cerebral mitochondrial function (reactive oxygen species (ROS) formation, total and nonprotein thiol levels, membrane potential (ΔΨm), metabolic function, and swelling), hepatic, cerebral, and muscular mercury levels, and hepatic, cerebral, and renal thioredoxin reductase (TrxR) activity were evaluated. MeHg caused hepatic and cerebral mitochondrial dysfunction and inhibited TrxR activity in liver (38,9%), brain (64,3%), and kidney (73,8%). Cotreatment with (PhSe)2 protected hepatic and cerebral mitochondrial thiols from depletion by MeHg but failed to completely reverse MeHg's effect on hepatic and cerebral mitochondrial dysfunction or hepatic, cerebral, and renal inhibition of TrxR activity. Additionally, the cotreatment with (PhSe)2 increased Hg accumulation in the liver (50,5%) and brain (49,4%) and increased the MeHg-induced motor deficits and body-weight loss. In conclusion, these results indicate that (PhSe)2 can increase Hg body burden as well as the neurotoxic effects induced by MeHg exposure in rats.


Subject(s)
Benzene Derivatives/toxicity , Methylmercury Compounds/toxicity , Mitochondria/drug effects , Organoselenium Compounds/toxicity , Animals , Brain/drug effects , Drug Combinations , Kidney/drug effects , Liver/drug effects , Mitochondria/enzymology , Mitochondria/pathology , Rats , Reactive Oxygen Species/metabolism , Thioredoxin-Disulfide Reductase/biosynthesis , Thioredoxin-Disulfide Reductase/drug effects
6.
Toxicol Appl Pharmacol ; 262(3): 341-8, 2012 Aug 01.
Article in English | MEDLINE | ID: mdl-22634334

ABSTRACT

The thioredoxin system, composed of thioredoxin reductase (TrxR), thioredoxin (Trx), and NADPH, is ubiquitous in all cells and involved in many redox-dependent signaling pathways. Curcumin, a naturally occurring pigment that gives a specific yellow color in curry food, is consumed in normal diet up to 100mg per day. This molecule has also been used in traditional medicine for the treatment of a variety of diseases. Curcumin has numerous biological functions, and many of these functions are related to induction of oxidative stress. However, how curcumin elicits oxidative stress in cells is unclear. Our previous work has demonstrated the way by which curcumin interacts with recombinant TrxR1 and alters the antioxidant enzyme into a reactive oxygen species (ROS) generator in vitro. Herein we reported that curcumin can target the cytosolic/nuclear thioredoxin system to eventually elevate oxidative stress in HeLa cells. Curcumin-modified TrxR1 dose-dependently and quantitatively transfers electrons from NADPH to oxygen with the production of ROS. Also, curcumin can drastically down-regulate Trx1 protein level as well as its enzyme activity in HeLa cells, which in turn remarkably decreases intracellular free thiols, shifting the intracellular redox balance to a more oxidative state, and subsequently induces DNA oxidative damage. Furthermore, curcumin-pretreated HeLa cells are more sensitive to oxidative stress. Knockdown of TrxR1 sensitizes HeLa cells to curcumin cytotoxicity, highlighting the physiological significance of targeting TrxR1 by curcumin. Taken together, our data disclose a previously unrecognized prooxidant mechanism of curcumin in cells, and provide a deep insight in understanding how curcumin works in vivo.


Subject(s)
Curcumin/pharmacology , HeLa Cells/drug effects , Oxidative Stress/drug effects , Thioredoxins/drug effects , Comet Assay , Dose-Response Relationship, Drug , HeLa Cells/metabolism , HeLa Cells/physiology , Humans , NADP/drug effects , NADP/metabolism , NADP/physiology , NADPH Oxidases/drug effects , NADPH Oxidases/metabolism , NADPH Oxidases/physiology , Reactive Oxygen Species/metabolism , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Thioredoxin-Disulfide Reductase/physiology , Thioredoxins/metabolism , Thioredoxins/physiology
7.
Int J Mol Med ; 29(4): 649-55, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22294162

ABSTRACT

We recently demonstrated that oridonin could induce apoptosis and senescence of colon cancer cells in vitro and in vivo. However, the underlying mechanism remains unknown. In this study, the involvement of reactive oxygen species in oridonin-induced cell death and senescence was investigated in colon adenocarcinoma-derived SW1116 cells. Oridonin increased intracellular hydrogen peroxide levels and reduced the glutathione content in a dose-dependent manner. N-acetylcysteine, a reactive oxygen species scavenger, not only blocked the oridonin-induced increase in hydrogen peroxide and glutathione depletion, but also blocked apoptosis and senescence induced by oridonin, as evidenced by the decrease in Annexin V and senescence-associated ß-galactosidase- positive cells and the inhibition of oridonin-induced upregulation of p53 and p16 and downregulation of c-Myc. Moreover, exogenous catalase could inhibit the increase in hydrogen peroxide and apoptosis induced by oridonin, but not the glutathione depletion and senescence. Furthermore, thioredoxin reductase (TrxR) activity was reduced by oridonin in vitro and in cells, which may cause the increase in hydrogen peroxide. In conclusion, the increase in hydrogen peroxide and glutathione depletion account for oridonin-induced apoptosis and senescence in colorectal cancer cells, and TrxR inhibition is involved in this process. Given the importance of TrxR as a novel cancer target in colon cancer, oridonin would be a promising clinical candidate. The mechanism of oridonin-induced inhibition of TrxR warrants further investigation.


Subject(s)
Apoptosis/drug effects , Diterpenes, Kaurane/pharmacology , Glutathione/metabolism , Hydrogen Peroxide/metabolism , Acetylcysteine/pharmacology , Annexin A5/metabolism , Cell Line, Tumor , Cellular Senescence , Colorectal Neoplasms/pathology , Cyclin-Dependent Kinase Inhibitor p16 , Down-Regulation , Humans , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Proto-Oncogene Proteins c-myc/genetics , Proto-Oncogene Proteins c-myc/metabolism , Reactive Oxygen Species/metabolism , Thioredoxin-Disulfide Reductase/antagonists & inhibitors , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism , Up-Regulation , beta-Galactosidase/metabolism
9.
Inorg Chem ; 48(4): 1577-87, 2009 Feb 16.
Article in English | MEDLINE | ID: mdl-19146434

ABSTRACT

New stable cationic organogold(III) complexes containing the "pincer" iminophosphorane ligand (2-C(6)H(4)-PPh(2)=NPh) have been prepared by reaction of the previously described [Au{kappa(2)-C,N-C(6)H(4)(PPh(2)=N(C(6)H(5))-2}Cl(2)] 1 and a combination of sodium or silver salts and appropriate ligands. The presence of the P atom in the PR(3) fragment has been used as a "spectroscopic marker" to study the in vitro stability (and oxidation state) of the new organogold complexes in solvents like dimethyl sulfoxide and water. Compounds with dithiocarbamato ligands and water-soluble phosphines of the general type [Au{kappa(2)-C,N-C(6)H(4)(PPh(2)=N(C(6)H(5))-2}(S(2)CN-R(2))]PF(6) (R = Me 2; Bz 3) and [Au{kappa(2)-C,N-C(6)H(4)(PPh(2)=N(C(6)H(5))-2}(PR(3))(n)Cl]PF(6) (PR(3) = P{Cp(m-C(6)H(4)-SO(3)Na)(2)} n = 1 4, n = 2 TPA {1,3,5-triaza-7-phosphaadamantane} 5) have been synthesized and characterized in solution and in the solid state (the crystal structure of 2 has been determined by X-ray diffraction studies). Complexes 1-5 have been tested as potential anticancer agents, and their cytotoxicity properties were evaluated in vitro against HeLa human cervical carcinoma and Jurkat-T acute lymphoblastic leukemia cells. Compounds 2 and 3 are quite cytotoxic for these two cell lines. There is a preferential induction of apoptosis in HeLa cells after treatment with 1-5. However in the case of the more cytotoxic complex (2), cell death is activated because of both apoptosis and necrosis. The interactions of 1-5 with Calf Thymus DNA have been evaluated by Thermal Denaturation methods. All these complexes show no or little (electrostatic) interaction with DNA. The interaction of 2 with two model proteins (cytochrome c and thioredoxin reductase) has been analyzed by spectroscopic methods (vis-UV and fluorescence). Compound 2 manifests a high reactivity toward both proteins. The mechanistic implications of these results are discussed here.


Subject(s)
Antineoplastic Agents/chemical synthesis , Apoptosis/drug effects , Organogold Compounds/chemical synthesis , Organogold Compounds/pharmacology , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cytochromes c/drug effects , Drug Stability , Humans , Ligands , Molecular Structure , Phosphoranes/chemistry , Solubility , Thioredoxin-Disulfide Reductase/drug effects
10.
Basic Clin Pharmacol Toxicol ; 101(2): 96-100, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17651309

ABSTRACT

Oxidative stress has been suggested to be an important molecular mechanism of toxic effects of lead in the kidney. Thioredoxin reductase-1 is a selenoprotein involved in many cellular redox processes. This study evaluated the effect of acute and chronic exposure intraperitoneally to lead acetate on thioredoxin reductase-1 activity and on other oxidative stress parameters in the rat kidney, as well as on indicators of renal function commonly used to assess lead poisoning. Acute exposure to 25 mg/kg lead acetate increased superoxide dismutase and thioredoxin reductase-1 activity (after 6, 24 and 48 hr), while exposure to 50 mg/kg lead acetate increased catalase activity (after 48 hr) and inhibited delta-aminolevulinate dehydratase activity (after 6, 24 and 48 hr) in the kidney (P < 0.05). Chronic exposure (30 days) to 5 mg/kg lead acetate inhibited delta-aminolevulinate dehydratase and increased glutathione S-transferase, non-protein thiol groups, catalase, thioredoxin reductase-1 and uric acid plasma levels, while exposure to 25 mg/kg lead acetate reduced body weight and delta-aminolevulinate dehydratase, but increased glutathione S-transferase, non-protein thiol groups and uric acid plasma levels (P < 0.05). No changes were observed in thiobarbituric acid reactive substances, glutathione peroxidase, creatinine or inorganic phosphate levels after either acute or chronic exposure. Our results suggest that thioredoxin reductase-1 may be an early indicator of acute exposure to low lead doses.


Subject(s)
Kidney/drug effects , Organometallic Compounds/pharmacology , Oxidative Stress/drug effects , Thioredoxin-Disulfide Reductase/drug effects , Animals , Creatinine/blood , Dose-Response Relationship, Drug , Kidney/enzymology , Kidney Function Tests , Male , Porphobilinogen Synthase/drug effects , Porphobilinogen Synthase/metabolism , Rats , Rats, Wistar , Thioredoxin Reductase 1 , Thioredoxin-Disulfide Reductase/metabolism , Uric Acid/blood
11.
Curr Opin Pharmacol ; 7(4): 392-7, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17611157

ABSTRACT

Thioredoxin (Trx) family members play critical roles in the regulation of cellular redox homeostasis. Cancer cells exist in a stressed environment and rely on the Trxs for protection against stress-disregulated redox signaling. The most extensively studied member of the family is Trx-1 whose levels are increased in many human cancers most likely in direct response to stress. Trx-1 contributes to many of the hallmarks of cancer including increased proliferation, resistance to cell death and increased angiogenesis. Trx-1 is a validated cancer drug target associated with aggressive tumor growth, resistance to standard therapy and decreased patient survival. A surrogate target for Trx-1 may be thioredoxin reductase (TR). Drugs that inhibit Trx-1 and TR are in clinical development with early promising results.


Subject(s)
Antineoplastic Agents/administration & dosage , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxins/drug effects , Animals , Drug Delivery Systems , Humans , Neoplasms/drug therapy , Neoplasms/physiopathology , Oxidation-Reduction , Signal Transduction/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Thioredoxins/metabolism
12.
Nutrition ; 23(2): 138-44, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17150329

ABSTRACT

OBJECTIVE: We examined the ability of sulforaphane and selenium to modify the expression of thioredoxin reductase (TR-1) and the glutathione peroxidases (GPX-1 and GPX-4) in EAhy926 cells. The effectiveness of these agents to protect cells against peroxidative damage was also assessed. METHODS: EAhy926 cells were supplemented with 40 nM of selenite and/or sulforaphane (10 microM) for 72 h and the expression of TR-1, GPX-1, and GPX-4 was assessed. Parallel cultures of selenium- and sulforaphane-treated cells were exposed to tertiary butyl hydroperoxide (t-BuOOH; 0-500 microM) for 20 h, and cell integrity was determined by the percentage of lactate dehydrogenase retained by the cellular layer. RESULTS: Selenite treatment increased the concentration of TR-1 (1.6 +/- 0.17 fold, P < 0.05), GPX-1 activity (8.2 +/- 1.08 fold, P < 0.001), and GPX-4 activity (3.1 +/- 0.25 fold, P < 0.001). Sulforaphane induced TR-1 expression in selenium-deficient cells (1.83 +/- 0.11 fold, P < 0.001) and selenium-supplemented cells (2.90 +/- 0.17 fold, P < 0.001) but had no inductive effect on GPX-1 or GPX-4. The combination of selenite and sulforaphane produced an increase in TR-1 expression that was significantly greater (P < 0.001) than that achieved when each agent was added alone. Selenium and sulforaphane acted in a synergistic manner to protect cells from damage caused by t-BuOOH. The susceptibility of cells to damage by t-BuOOH increased in this order: control > sulforaphane > selenite > selenite + sulforaphane (P < 0.0001). CONCLUSION: In endothelial cells, sulforaphane increases TR-1 but not GPX-1 and GPX-4 and in doing so confers protection against oxidative damage induced by lipid hydroperoxides. The results highlight the potential important role of TR-1 over the GPXs in protecting endothelial cells from oxidative cell damage. We also suggest that our results indicate a potential beneficial role for sulforaphane in protecting the vascular endothelium from oxidative damage.


Subject(s)
Antioxidants/pharmacology , Endothelium, Vascular , Glutathione Peroxidase/drug effects , Selenium/pharmacology , Thiocyanates/pharmacology , Thioredoxin-Disulfide Reductase/drug effects , Anticarcinogenic Agents/pharmacology , Cells, Cultured , Endothelium, Vascular/cytology , Endothelium, Vascular/drug effects , Endothelium, Vascular/enzymology , Gene Expression Regulation, Enzymologic , Glutathione Peroxidase/metabolism , Humans , Isothiocyanates , L-Lactate Dehydrogenase/drug effects , L-Lactate Dehydrogenase/metabolism , Lipid Peroxidation , Oxidative Stress/drug effects , Oxidative Stress/physiology , Sulfoxides , Thioredoxin-Disulfide Reductase/metabolism , Glutathione Peroxidase GPX1
13.
Free Radic Res ; 40(9): 936-43, 2006 Sep.
Article in English | MEDLINE | ID: mdl-17015273

ABSTRACT

A major fraction of the essential trace element selenium circulating in human blood plasma is present as selenoprotein P (SeP). As SeP associates with endothelial membranes, the participation of SeP in selenium-mediated protection against oxidative damage was investigated, using the human endothelial cell line Ea.hy926 as a model system. Hepatocyte-derived SeP prevented tert-butylhydroperoxide (t-BHP)-induced oxidative cell death of Ea.hy926 cells in a similar manner as did sodium selenite, counteracting a t-BHP-induced loss of cellular membrane integrity. Protection was detected after at least 10 h of SeP supplementation and it peaked at 24 h. SeP time-dependently stimulated the expression of cytosolic glutathione peroxidase (cGPx) and increased the enzymatic activities of glutathione peroxidase (GPx) and thioredoxin reductase (TR). The cGPx inhibitor mercaptosuccinate as well as the gamma-glutamylcysteine synthetase inhibitor buthionine sulfoximine counteracted the SeP-mediated protection, while the TR inhibitors cisplatin and auranofin had no effect. The presented data suggest that selenium supplementation by SeP prevents oxidative damage of human endothelial cells by restoring expression and enzymatic activity of GPx.


Subject(s)
Endothelial Cells/drug effects , Glutathione Peroxidase/drug effects , Oxidative Stress/drug effects , Selenoprotein P/pharmacology , Buthionine Sulfoximine/pharmacology , Cell Death/drug effects , Cell Line , Cells, Cultured , Endothelial Cells/metabolism , Enzyme Activation/drug effects , Glutathione Peroxidase/antagonists & inhibitors , Glutathione Peroxidase/metabolism , Humans , Selenoprotein P/antagonists & inhibitors , Succinates/pharmacology , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Time Factors
14.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao ; 27(5): 606-10, 2005 Oct.
Article in Chinese | MEDLINE | ID: mdl-16274042

ABSTRACT

OBJECTIVE: To establish gemcitabine-resistant pancreatic cancer cell strain and study the role of thioredoxin reductase (TrxR) in drug-resistant process. METHODS: Gemcitabine-resistant pancreatic cancer cell strain SW1990/GZ was induced by increasing drug dosage intermittently, then the changes of its biological features and the activity of TrxR were examined. RESULTS: Stable drug-resistant SW1990/GZ cell strain was established by culturing with gemcitabine for 9 months. The morphology and growth characteristics of the cell strain changed remarkably. The cells shrunk and became rounder; its endoplasm expanded; granular substances increased; and the doubling-time was prolonged. Resistance of the cell line to gemcitabine, fluorouracil, adriamycin, and mitomycin significantly increased. The TrxR activity of the drug-resistant cells was increased markedly. CONCLUSION: SW1990/GZ has certain multidrug resistance to some chemotherapy drugs, and TrxR plays a role in the drug-resistant process.


Subject(s)
Deoxycytidine/analogs & derivatives , Drug Resistance, Neoplasm/drug effects , Pancreatic Neoplasms/pathology , Thioredoxin-Disulfide Reductase/metabolism , Antimetabolites, Antineoplastic/pharmacology , Cell Line, Tumor , Deoxycytidine/pharmacology , Humans , Pancreatic Neoplasms/enzymology , Thioredoxin-Disulfide Reductase/drug effects , Gemcitabine
15.
J Cell Physiol ; 203(3): 529-37, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15521073

ABSTRACT

Thioredoxin reductase (TrxR) is a selenoprotein that catalyzes the reduction of the active site disulfide of thioredoxin (Trx), which regulates the redox status of the cells. In the present study, we found that TrxR1, one of the three TrxR isozymes, was induced by cadmium as well as tumor necrosis factor alpha (TNFalpha) in bovine arterial endothelial cells (BAEC), and investigated the mechanism of cadmium-induced TrxR1 expression. We here showed that cadmium, differently from TNFalpha, enhanced the promoter activity of the 5'-flanking region of human TrxR1 gene (nucleotides -1692 to +49). Deletion and site-directed mutation of antioxidant responsive element (ARE) (nucleotides -62 to -48) in this region abolished the response to cadmium. Overexpression of NF-E2-related factor-2 (Nrf2) augmented the TrxR1 promoter activity. In contrast, overexpression of the dominant negative mutant of Nrf2 suppressed cadmium-induced activation of TrxR1 promoter through the ARE. Chromatin immunoprecipitation (ChIP) assays showed that anti-Nrf2 antibody precipitated ARE from the chromatin of the cadmium-treated cells. These results indicated that cadmium-induced TrxR1 gene expression is mediated by the activation of Nrf2 transcription factor and its binding to ARE in the TrxR1 gene promoter. We further found that in addition to cadmium, the activators of Nrf2, such as diethyl maleate (DEM) and arsenite, induced both TrxR1 and Trx gene expression in BAEC. Nrf2 might play an important role in the regulation of the cellular Trx system consisting of Trx and TrxR.


Subject(s)
Cadmium/pharmacology , DNA-Binding Proteins/metabolism , Endothelial Cells/metabolism , Genes, Regulator/genetics , Thioredoxin-Disulfide Reductase/metabolism , Trans-Activators/metabolism , 5' Flanking Region/drug effects , 5' Flanking Region/genetics , Animals , Arsenites/pharmacology , Cattle , Cell Line , DNA-Binding Proteins/genetics , Endothelial Cells/drug effects , Gene Expression Regulation/drug effects , Gene Expression Regulation/genetics , Genes, Regulator/drug effects , Humans , Malates/pharmacology , Mutagenesis, Site-Directed/genetics , Mutation/genetics , NF-E2-Related Factor 2 , Promoter Regions, Genetic/drug effects , Promoter Regions, Genetic/genetics , Thioredoxin Reductase 1 , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/genetics , Trans-Activators/genetics , Transcriptional Activation/drug effects , Transcriptional Activation/genetics , Tumor Necrosis Factor-alpha/pharmacology , Up-Regulation/drug effects , Up-Regulation/genetics
16.
Carcinogenesis ; 26(1): 125-31, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15459019

ABSTRACT

Previous studies in animals and humans have shown that selenium compounds can prevent cancer development. In this work we studied the tumor preventive effect of selenium supplementation, administrated as selenite, in the initiation, promotion and progression phases in a synchronized rat model for chemically induced hepatocarcinogenesis, the resistant hepatocyte model. Selenite in supra-nutritional but subtoxic doses (1 and 5 p.p.m.) was administrated to the animals through the drinking water. Such supplementation during the initiation phase did not have a tumor preventive effect. However, selenite treatment during the promotion phase decreased the volume fraction of pre-neoplastic liver nodules from 38% in control animals to 25 (1 p.p.m.) and 14% (5 p.p.m.) in the selenite-supplemented groups. In addition the cell proliferation within the nodules decreased from 42% in the control to 22 (1 p.p.m.) and 17% (5 p.p.m.). Immunohistochemical staining for the selenoenzyme thioredoxin reductase 1 revealed an increased expression of the enzyme in liver nodules compared with the surrounding tissue. The activity was reduced to 50% in liver homogenates from selenium-treated animals but the activity of the selenoenzyme glutathione peroxidase was essentially unaltered. Selenite treatment (5 p.p.m.) during the progression phase resulted in a significantly lower volume fraction of liver tumors (14 compared with 26%) along with a decrease in cell proliferation within the tumors (34 compared with 63%). Taken together our data indicate that the carcinogenetic process may be prevented by selenium supplementation both during the promotion and the progression phase.


Subject(s)
Liver Neoplasms, Experimental/pathology , Liver Neoplasms, Experimental/prevention & control , Selenium/administration & dosage , Animals , Immunohistochemistry , Liver Neoplasms, Experimental/metabolism , Models, Animal , Rats , Thioredoxin Reductase 1 , Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Time Factors
17.
J Cell Biol ; 160(7): 1139-50, 2003 Mar 31.
Article in English | MEDLINE | ID: mdl-12668662

ABSTRACT

In vitro delivery of the diphtheria toxin catalytic (C) domain from the lumen of purified early endosomes to the external milieu requires the addition of both ATP and a cytosolic translocation factor (CTF) complex. Using the translocation of C-domain ADP-ribosyltransferase activity across the endosomal membrane as an assay, the CTF complex activity was 650-800-fold purified from human T cell and yeast extracts, respectively. The chaperonin heat shock protein (Hsp) 90 and thioredoxin reductase were identified by mass spectrometry sequencing in CTF complexes purified from both human T cell and yeast. Further analysis of the role played by these two proteins with specific inhibitors, both in the in vitro translocation assay and in intact cell toxicity assays, has demonstrated their essential role in the productive delivery of the C-domain from the lumen of early endosomes to the external milieu. These results confirm and extend earlier observations of diphtheria toxin C-domain unfolding and refolding that must occur before and after vesicle membrane translocation. In addition, results presented here demonstrate that thioredoxin reductase activity plays an essential role in the cytosolic release of the C-domain. Because analogous CTF complexes have been partially purified from mammalian and yeast cell extracts, results presented here suggest a common and fundamental mechanism for C-domain translocation across early endosomal membranes.


Subject(s)
Catalytic Domain , Cytosol/metabolism , Diphtheria Toxin/metabolism , T-Lymphocytes/metabolism , Thioredoxin-Disulfide Reductase/metabolism , Benzoquinones , Cell Line , Endocytosis , Endosomes/metabolism , HSP90 Heat-Shock Proteins/analysis , HSP90 Heat-Shock Proteins/metabolism , Humans , Lactams, Macrocyclic , Lactones/pharmacology , Macrolides , Mass Spectrometry , Peptide Elongation Factor 2/metabolism , Quinones/pharmacology , Thioredoxin-Disulfide Reductase/analysis , Thioredoxin-Disulfide Reductase/drug effects , Yeasts
18.
Postepy Hig Med Dosw ; 56(2): 155-67, 2002.
Article in Polish | MEDLINE | ID: mdl-12107960

ABSTRACT

Thioredoxin reductase (TrxR) is the first selenoenzyme containing selenocysteine in the active center and FAD as a second prosthetic group. TrxR catalyses the NADPH-dependent reduction of thioredoxin and of many other physiologically important substrates. TrxR exhibits a many-fold increase in the activity in tumor cells and stimulates their proliferation as well the phenotype changes. Some gold compounds and a number of other clinically and experimentally tested drugs have been shown to inhibit TrxR. The involvement of TrxR/Trx/NADPH system in a broad spectrum of cellular processes renders it a potential target for therapeutic approaches.


Subject(s)
Thioredoxin-Disulfide Reductase/drug effects , Thioredoxin-Disulfide Reductase/metabolism , Animals , Humans , Neoplasms/enzymology , Selenium/deficiency , Selenium/metabolism , Thioredoxin-Disulfide Reductase/chemistry
19.
Biochem Pharmacol ; 63(10): 1875-84, 2002 May 15.
Article in English | MEDLINE | ID: mdl-12034372

ABSTRACT

The human U-1285 and GLC(4) cell lines, both derived from small cell carcinoma of the lung, are present in doxorubicin-sensitive (U-1285 and GLC(4)) and doxorubicin-resistant MRP-expressing (U-1285dox and GLC(4)/ADR) variants. These sublines were examined here with respect to their susceptibilities to the toxic effects of selenite and compared to the toxic effects of selenite on the promyelocytic leukemia cell line HL-60 and its doxorubicin-resistant P-glycoprotein expressing variant. The drug-resistant U-1285dox and GLC(4)/ADR sublines proved to be 3- and 4-fold, respectively, more sensitive to the cytotoxicity of selenite than the drug-sensitive U-1285 and GLC(4) sublines, whereas no difference was observed between the HL-60 sublines. The presence of doxorubicin at a concentration equal to the IC(10) did not significantly potentiate the toxic effects of selenite. The presence of selenite did not significantly affect the expression of the multi-drug resistant proteins (MRP1, LRP and topoisomerase IIalpha) in the drug-resistant cells. The activities of thioredoxin reductase (TrxR) were higher (50 and 25%, respectively) in the drug resistant cell sublines U-1285dox and GLC(4)/ADR compared to the drug-sensitive parental lines. The activity of glutathione reductase (GR) was essentially the same in the drug-sensitive and -resistant cell lines. Exposure to selenite resulted in a 4-fold increase in both TrxR and GR activities in U-1285 cells, an effect, which was less pronounced in the presence of doxorubicin. Under similar conditions the increase in the TrxR activity in the resistant U-1285dox cell line, was only 30% and the activity of GR was unaltered. Different responses in the activity of the key enzymes in selenium metabolism are one possible mechanism explaining the differential cytotoxicity of selenium in these cells.


Subject(s)
Drug Resistance, Neoplasm/physiology , Glutathione Reductase/metabolism , Sodium Selenite/pharmacology , Thioredoxin-Disulfide Reductase/metabolism , Blotting, Western , Cell Division/drug effects , Glutathione Reductase/drug effects , Humans , Lung Neoplasms/pathology , Thioredoxin-Disulfide Reductase/drug effects , Tumor Cells, Cultured
20.
Chem Res Toxicol ; 14(3): 305-11, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11258980

ABSTRACT

Thioredoxin reductase (TR), an NADPH-dependent flavoenzyme that catalyzes the reduction of many disulfide-containing substrates, plays an important role in the cellular response to oxidative stress. Trivalent arsenicals, especially methyl As that contains trivalent arsenic (MAs(III)), are potent noncompetitive inhibitors of TR purified from mouse liver. Because MAs(III) is produced in the biomethylation of As, it was postulated that the extent of inhibition of TR in cultured rat hepatocytes would correlate with the intracellular concentration of methyl As. Exposure of cultured hepatocytes to inorganic As(III) (iAs(III)), MAs(III), or aurothioglucose (ATG, a competitive inhibitor of TR activity) for 30 min caused a concentration-dependent reduction in TR activity. The estimated IC(50) was >>100 microM for iAs(III), approximately 10 microM for ATG, and approximately 3 microM for MAs(III). In hepatocytes exposed to 1 microM MAs(III) for up to 24 h, the inhibition of TR activity was maximal ( approximately 40%) after exposure for 15 min. After exposure for 3 h [when most MAs(III) has been converted to dimethyl As (DMAs)], TR activity in these cells had returned to control levels. Notably, exposure of the cell to 50 microM DMAs(III) did not affect TR activity. In hepatocytes exposed to 10 microM iAs(III) for up to 24 h, the inhibition of TR activity was progressive; at 24 h, activity was reduced approximately 35%. Following exposure to iAs(III) or MAs(III), the extent of inhibition of TR activity correlated strongly with the intracellular concentration of MAs. Taken together, these results suggest that arsenicals formed in the course of cellular metabolism of As are potent inhibitors of TR activity. In particular, MAs(III), an intermediate in the metabolic pathway, is an especially potent inhibitor of TR. Hence, the capacity of cells to produce or consume the intermediates in the pathway for As methylation may be an important determinant of susceptibility to the toxic effects of As.


Subject(s)
Arsenicals/pharmacology , Thioredoxin-Disulfide Reductase/metabolism , Animals , Arsenic/pharmacology , Cell Culture Techniques , Dose-Response Relationship, Drug , Hepatocytes/drug effects , Hepatocytes/enzymology , Male , Oxidative Stress , Rats , Rats, Inbred F344 , Thioredoxin-Disulfide Reductase/drug effects
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