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Douglas R Spitz - One of the best experts on this subject based on the ideXlab platform.
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2 deoxy d glucose causes cytotoxicity oxidative stress and radiosensitization in pancreatic cancer
Free Radical Biology and Medicine, 2008Co-Authors: Mitchell C Coleman, Douglas R Spitz, Carla Asbury, David H Daniels, Nukhet Aykinburns, Brian J Smith, Joseph J CullenAbstract:Glucose metabolism as assessed by (18)FDG PET imaging provides prognostic information in patients with pancreatic cancer but the implications of manipulating glucose metabolism for therapeutic purposes are unknown. Based on previous results with other cancer cell types, we hypothesized that inhibition of glucose metabolism in pancreatic cancer cells would cause cell killing via oxidative stress resulting from disruptions in thiol metabolism. 2-Deoxy-D-glucose (2DG), a chemical inhibitor of glucose metabolism, and glucose deprivation induced cytotoxicity in human pancreatic cancer cells in a time-and dose-dependent manner as well as causing significant increases in metabolic oxidative stress as measured by increased Glutathione Disulfide accumulation and NADP(+)/NADPH ratios. Simultaneous administration of the thiol antioxidant N-acetylcysteine protected pancreatic cancer cells against the c-ytotoxic effects of 2DG as well as reversing 2DG-induced Glutathione Disulfide accumulation and augmenting intracellular cysteine pools. In nude mice with heterotopic pancreatic tumors, the combination of 2DG and ionizing radiation resulted in greater inhibition of tumor growth and increased survival, relative to either agent alone. These results support the hypothesis that inhibiting glucose metabolism causes cytotoxicity in human pancreatic cancer cells via metabolic oxidative stress and disruptions in thiol metabolism. These results also support the speculation that inhibitors of glucose metabolism can be used in combination with classical oxidative stress-inducing agents (such as ionizing radiation) to enhance therapeutic responses in pancreatic cancer.
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2 deoxy d glucose combined with cisplatin enhances cytotoxicity via metabolic oxidative stress in human head and neck cancer cells
Cancer Research, 2007Co-Authors: Andrean L Simons, Iman M Ahmad, David Mattson, Kenneth J Dornfeld, Douglas R SpitzAbstract:Glucose deprivation has been hypothesized to cause cytotoxicity by inducing metabolic oxidative stress in human cancer cells. The current work tests the hypothesis that 2-deoxy-d-glucose (2DG) combined with cisplatin [cis-diamminedichloroplatinum(II)] can enhance cytotoxicity in human head and neck cancer cells (FaDu) by mechanisms involving oxidative stress. Exposure of FaDu cells to the combination of 2DG and cisplatin resulted in a significant decrease in cell survival when compared with 2DG or cisplatin alone. Treatment with 2DG and cisplatin also caused perturbations in parameters indicative of oxidative stress, including decreased intracellular total Glutathione and increased percentage of Glutathione Disulfide. Simultaneous treatment with the thiol antioxidant N-acetylcysteine (NAC) inhibited parameters indicative of oxidative stress, as well as protected FaDu cells from the cytotoxic effects of cisplatin alone and the combination of 2DG and cisplatin. In addition, polyethylene glycol-conjugated antioxidant enzymes (PEG-superoxide dismutase and PEG-catalase) also protected FaDu cells from 2DG toxicity. An inhibitor of Glutathione synthesis, l-buthionine-[S,R]-sulfoximine (BSO), sensitized FaDu cells to the cytotoxic effects of 2DG and cisplatin, and these effects were inhibited by NAC. Furthermore, the combination of 2DG, cisplatin, and BSO significantly increased the percentage of Glutathione Disulfide, which was also inhibited by NAC. These results support the hypothesis that exposure of human head and neck cancer cells to 2DG combined with cisplatin enhances cytotoxicity via metabolic oxidative stress. These findings provide a strong biochemical rationale for evaluating inhibitors of glucose and hydroperoxide metabolism in combination with cisplatin for the treatment of head and neck cancer.
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measurement of Glutathione Glutathione Disulfide and other thiols in mammalian cell and tissue homogenates using high performance liquid chromatography separation of n 1 pyrenyl maleimide derivatives
Methods in Enzymology, 1999Co-Authors: Lisa A Ridnour, Nuran Ercal, Roger Winters, Douglas R SpitzAbstract:Publisher Summary This chapter discusses the measurement of Glutathione, Glutathione Disulfide, and other thiols in mammalian cell and tissue homogenates using high-performance liquid chromatography (HPLC) separation of N-(1-Pyrenyl)maleimide (NPM) derivatives. As Glutathione and cellular thiol-related research progresses, the role of these thiols has been extended from acting only in the maintenance of steady-state redox equilibrium to a proposed involvement in many stress induced metabolic and bioregulator functions, including signal transduction and gene expression. The NPM assay provides a rapid and simple method for analyzing both oxidized and reduced Glutathione, as well as other thiols, including cysteine, 7-glutamylcysteine, homocysteine, cysteinylglycine, and N-acetylcysteine. The NPM assay provides an excellent method for determining modulations in intracellular thiols caused by oxidative stress. Because changes in redox potential have been associated with alterations in metabolism, signal transduction, and gene expression, the NPM assay provides a sensitive and accurate means of correlating thiol status with these biological processes.
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analysis of Glutathione Glutathione Disulfide cysteine homocysteine and other biological thiols by high performance liquid chromatography following derivatization by n 1 pyrenyl maleimide
Analytical Biochemistry, 1995Co-Authors: R A Winters, J Zukowski, Nuran Ercal, R H Matthews, Douglas R SpitzAbstract:Abstract The compound N-(1-pyrenyl)maleimide (NPM) reacts with free sulfhydryl groups to form fluorescent derivatives. A new method for measurement of Glutathione and other biological thiols utilizing reverse-phase high-performance liquid chromatography to separate and quantify these derivatives is described. Separation and quantification of Glutathione, cysteine, homocysteine, cysteinylglycine, and γ-glutamylcysteine derivatives are achieved. The method allows for the measurement of Glutathione Disulfide by masking free Glutathione with 2-vinylpyridine, reducing Glutathione Disulfide with Glutathione reductase, and measuring the resulting Glutathione. Coefficient of variations for the various thiols measured by the NPM method range from 1.5 to 8.8%. The lower detection limit is around 50 fmol of Glutathione. NPM derivatives are shown to be stable for 2 months at 4°C. Between 94.2 and 97.2% of Glutathione and/or Glutathione Disulfide added to a sample is recovered using the NPM method. The NPM method is compared to the monobromobimane high-performance liquid chromatography method and the Tietze assay by measuring Glutathione in homogenates from five different cell lines. The newly developed method offers some advantages over the currently accepted techniques, including specificity, speed, sensitivity, and ease of use.
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analysis of Glutathione Glutathione Disulfide cysteine homocysteine and other biological thiols by high performance liquid chromatography following derivatization by n 1 pyrenyl maleimide
Analytical Biochemistry, 1995Co-Authors: Roger Winters, J Zukowski, Nuran Ercal, R H Matthews, Douglas R SpitzAbstract:The compound N-(1-pyrenyl)maleimide (NPM) reacts with free sulfhydryl groups to form fluorescent derivatives. A new method for measurement of Glutathione and other biological thiols utilizing reverse-phase high-performance liquid chromatography to separate and quantify these derivatives is described. Separation and quantification of Glutathione, cysteine, homocysteine, cysteinylglycine, and gamma-glutamylcysteine derivatives are achieved. The method allows for the measurement of Glutathione Disulfide by masking free Glutathione with 2-vinylpyridine, reducing Glutathione Disulfide with Glutathione reductase, and measuring the resulting Glutathione. Coefficient of variations for the various thiols measured by the NPM method range from 1.5 to 8.8%. The lower detection limit is around 50 fmol of Glutathione. NPM derivatives are shown to be stable for 2 months at 4 degrees C. Between 94.2 and 97.2% of Glutathione and/or Glutathione Disulfide added to a sample is recovered using the NPM method. The NPM method is compared to the monobromobimane high-performance liquid chromatography method and the Tietze assay by measuring Glutathione in homogenates from five different cell lines. The newly developed method offers some advantages over the currently accepted techniques, including specificity, speed, sensitivity, and ease of use.
Ralf Dringen - One of the best experts on this subject based on the ideXlab platform.
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exposure of cultured astrocytes to menadione triggers rapid radical formation Glutathione oxidation and mrp1 mediated export of Glutathione Disulfide
Neurochemical Research, 2019Co-Authors: Johann Steinmeier, Ralf DringenAbstract:Menadione (2-methyl-1,4-naphthoquinone) is a synthetic derivative of vitamin K that allows rapid redox cycling in cells and thereby generates reactive oxygen species (ROS). To test for the consequences of a treatment of brain astrocytes with menadione, we incubated primary astrocyte cultures with this compound. Incubation with menadione in concentrations of up to 30 µM did not affect cell viability. In contrast, exposure of astrocytes to 100 µM menadione caused a time-dependent impairment of cellular metabolism and cell functions as demonstrated by impaired glycolytic lactate production and strong increases in the activity of extracellular lactate dehydrogenase and in the number of propidium iodide-positive cells within 4 h of incubation. In addition, already 5 min after exposure of astrocytes to menadione a concentration-dependent increase in the number of ROS-positive cells as well as a concentration-dependent and transient accumulation of cellular Glutathione Disulfide (GSSG) were observed. The rapid intracellular GSSG accumulation was followed by an export of GSSG that was prevented in the presence of MK571, an inhibitor of the multidrug resistance protein 1 (Mrp1). Menadione-induced Glutathione (GSH) oxidation and ROS formation were found accelerated after glucose-deprivation, while the presence of dicoumarol, an inhibitor of the menadione-reducing enzyme NQO1, did not affect the menadione-dependent GSSG accumulation. Our study demonstrates that menadione rapidly depletes cultured astrocytes of GSH via ROS-induced oxidation to GSSG that is subsequently exported via Mrp1.
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adsorption and orientation of the physiological extracellular peptide Glutathione Disulfide on surface functionalized colloidal alumina particles
Journal of the American Chemical Society, 2013Co-Authors: Fabian Meder, Ralf Dringen, Henrik Hintz, Yvonne Koehler, Maike M Schmidt, Laura Treccani, Kurosch RezwanAbstract:Understanding the interrelation between surface chemistry of colloidal particles and surface adsorption of biomolecules is a crucial prerequisite for the design of materials for biotechnological and nanomedical applications. Here, we elucidate how tailoring the surface chemistry of colloidal alumina particles (d50 = 180 nm) with amino (−NH2), carboxylate (−COOH), phosphate (−PO3H2) or sulfonate (−SO3H) groups affects adsorption and orientation of the model peptide Glutathione Disulfide (GSSG). GSSG adsorbed on native, −NH2-functionalized, and −SO3H-functionalized alumina but not on −COOH- and −PO3H2-functionalized particles. When adsorption occurred, the process was rapid (≤5 min), reversible by application of salts, and followed a Langmuir adsorption isotherm dependent on the particle surface functionalization and ζ potential. The orientation of particle bound GSSG was assessed by the release of Glutathione after reducing the GSSG Disulfide bond and by ζ potential measurements. GSSG is likely to bind via...
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the multidrug resistance protein 1 mrp1 but not mrp5 mediates export of Glutathione and Glutathione Disulfide from brain astrocytes
Journal of Neurochemistry, 2006Co-Authors: Tobias Minich, Ralf Dringen, Jorg B Schulz, Jan Riemer, Peter R Wielinga, Jan WijnholdsAbstract:Astrocytes play an important role in the Glutathione (GSH) metabolism of the brain. To test for an involvement of multidrug resistance protein (Mrp) 1 and 5 in the release of GSH and Glutathione Disulfide (GSSG) from astrocytes, we used astrocyte cultures from wild-type, Mrp1-deficient [Mrp1(–/–)] and Mrp5-deficient [Mrp5(–/–)] mice. During incubation of wild-type or Mrp5(–/–) astrocytes, GSH accumulated in the medium at a rate of about 3 nmol/(h.mg), whereas the export of GSH from Mrp1(–/–) astrocytes was only one-third of that. In addition, Mrp1(–/–) astrocytes had a 50% higher specific GSH content than wild-type or Mrp5(–/–) cells. The presence of 50 μm of the Mrp inhibitor MK571 inhibited the rate of GSH release from wild-type and Mrp5(–/–) astrocytes by 60%, but stimulated at the low concentration of 1 μm GSH release by 40%. In contrast, both concentrations of MK571 did not affect GSH export from Mrp1(–/–) astrocytes. Moreover, in contrast to wild-type and Mrp5(–/–) cells, GSSG export during H2O2 stress was not observed for Mrp1(–/–) astrocytes. These data demonstrate that in astrocytes Mrp1 mediates 60% of the GSH export, that Mrp1 is exclusively responsible for GSSG export and that Mrp5 does not contribute to these transport processes.
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multidrug resistance protein 1 mediated export of Glutathione and Glutathione Disulfide from brain astrocytes
Methods in Enzymology, 2005Co-Authors: Johannes Hirrlinger, Ralf DringenAbstract:Abstract Many cell types are known to release Glutathione (GSH) and Glutathione Disulfide (GSSG). Multidrug resistance proteins (Mrps) have been identified to be involved in these export processes. In the brain, astrocytes have key functions in GSH metabolism and in antioxidative defense. These cells release large amounts of GSH under unstressed conditions as well as GSSG during oxidative stress. This chapter describes experimental paradigms to analyze the release of the physiological Mrp substrates GSH and GSSG from cultured astrocytes. These assay systems can be used to screen for compounds that affect Mrp1‐mediated export from astrocytes and therefore could interfere with the antioxidative defense system of the brain. In addition, our methods could be useful in investigating mechanisms of export of GSH and GSSG from other cell types.
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the multidrug resistance protein mrp1 mediates the release of Glutathione Disulfide from rat astrocytes during oxidative stress
Journal of Neurochemistry, 2001Co-Authors: Johannes Hirrlinger, Jorg Konig, Dietrich Keppler, Jorg Lindenau, Jorg B Schulz, Ralf DringenAbstract:The release of Glutathione Disulfide has been considered an important process for the maintenance of a reduced thiol redox potential in cells during oxidative stress. In cultured rat astrocytes, permanent hydrogen peroxide-induced oxidative stress caused a rapid increase in intracellular Glutathione Disulfide, which was followed by the appearance of Glutathione Disulfide in the medium. Under these conditions, the viability of the cells was not compromised. In the presence of cyclosporin A and the quinoline-derivative MK571, inhibitors of multidrug resistance proteins (MRP1 and MRP2), Glutathione Disulfide accumulated in cells and the release of Glutathione Disulfide from astrocytes during H2O2 stress was potently inhibited, suggesting a contribution of MRP1 or MRP2 in the release of Glutathione Disulfide from astrocytes. Using RT-PCR we amplified a cDNA from astroglial RNA with a high degree of homology to MRP1 from humans and mouse. In contrast, no fragment was amplified by using primers specific for rat MRP2. In addition, the presence of MRP1 protein in astrocytes was demonstrated by its immunolocalization in cells expressing the astroglial marker protein glial fibrillary acidic protein. Our data identify rat astrocytes as a MRP1-expressin, brain cell type and demonstrate that this transporter participates in the release of Glutathione Disulfide from astrocytes during oxidative stress.
Motoji Fujioka - One of the best experts on this subject based on the ideXlab platform.
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reversible inactivation of recombinant rat liver guanidinoacetate methyltransferase by Glutathione Disulfide
Archives of Biochemistry and Biophysics, 1991Co-Authors: Kiyoshi Konishi, Motoji FujiokaAbstract:Abstract Recombinant rat liver guanidinoacetate methyltransferase is inactivated by Glutathione Disulfide (GSSG) following pseudo-first-order kinetics. A second-order rate constant of 20.8 m −1 min−1 is obtained at pH 7.5 and 30 °C. The inactivation is fully reversed by Glutathione (GSH) in a pseudo-first-order fashion with a second-order rate constant of 11.1 m −1 min−1. The rate of inactivation is not affected by S-adenosylmethionine or guanidinoacetate, but complete protection against inactivation is observed in the presence of sinefungin plus guanidinoacetate. At equilibrium in the buffers containing various concentrations of GSH and GSSG, the enzyme shows activities that are dependent on the ratio but not on the total concentration of GSH and GSSG. A hyperbolic relationship is obtained between enzyme activity and [GSH] [GSSG] ratio. The inactivation by GSSG is associated with the disappearance of ~ 1 mol of sulfhydryl group per mole of enzyme. These results indicate that inactivation of guanidinoacetate methyltransferase by GSSG is the consequence of the formation of a mixed Disulfide between a protein thiol and Glutathione. The equilibrium constant for the redox reaction, E-SH + GSSG ⇌ E-SSG + GSH, obtained from the equilibrium data (1.69) is in good agreement with the value determined as the ratio of second-order rate constants for reactivation and inactivation (1.87). The cysteine residue engaged in the mixed Disulfide with Glutathione is identified as Cys-15 by peptide analysis after consecutive treatment of the GSSG-inactivated enzyme with N-ethylmaleimide, 2-mercaptoethanol, and [14C]iodoacetate. The GSSG-inactivated enzyme binds S-adenosylmethionine but not guanidinoacetate in the presence and absence of sinefungin. Native guanidinoacetate methyltransferase binds guanidinoacetate in the presence of sinefungin. The low overall redox equilibrium constant of 1.7–1.9 found for the reaction between guanidinoacetate methyltransferase and GSSG suggests that the activity of the enzyme is not amenable to modulation by the change in intracellular [GSH] [GSSG] ratio.
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reversible inactivation of recombinant rat liver guanidinoacetate methyltransferase by Glutathione Disulfide
Archives of Biochemistry and Biophysics, 1991Co-Authors: Kiyoshi Konishi, Motoji FujiokaAbstract:Recombinant rat liver guanidinoacetate methyltransferase is inactivated by Glutathione Disulfide (GSSG) following pseudo-first-order kinetics. A second-order rate constant of 20.8 M-1 min-1 is obtained at pH 7.5 and 30 degrees C. The inactivation is fully reversed by Glutathione (GSH) in a pseudo-first-order fashion with a second-order rate constant of 11.1 M-1 min-1. The rate of inactivation is not affected by S-adenosylmethionine or guanidinoacetate, but complete protection against inactivation is observed in the presence of sinefungin plus guanidinoacetate. At equilibrium in the buffers containing various concentrations of GSH and GSSG, the enzyme shows activities that are dependent on the ratio but not on the total concentration of GSH and GSSG. A hyperbolic relationship is obtained between enzyme activity and [GSH]/[GSSG] ratio. The inactivation by GSSG is associated with the disappearance of approximately 1 mol of sulfhydryl group per mole of enzyme. These results indicate that inactivation of guanidinoacetate methyltransferase by GSSG is the consequence of the formation of a mixed Disulfide between a protein thiol and Glutathione. The equilibrium constant for the redox reaction, E-SH + GSSG in equilibrium with E-SSG + GSH, obtained from the equilibrium data (1.69) is in good agreement with the value determined as the ratio of second-order rate constants for reactivation and inactivation (1.87). The cysteine residue engaged in the mixed Disulfide with Glutathione is identified as Cys-15 by peptide analysis after consecutive treatment of the GSSG-inactivated enzyme with N-ethylmaleimide, 2-mercaptoethanol, and [14C]iodoacetate. The GSSG-inactivated enzyme binds S-adenosyl-methionine but not guanidinoacetate in the presence and absence of sinefungin. Native guanidinoacetate methyltransferase binds guanidinoacetate in the presence of sinefungin. The low overall redox equilibrium constant of 1.7-1.9 found for the reaction between guanidinoacetate methyltransferase and GSSG suggests that the activity of the enzyme is not amenable to modulation by the change in intracellular [GSH]/[GSSG] ratio.
Danyelle M Townsend - One of the best experts on this subject based on the ideXlab platform.
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preclinical pharmacokinetic analysis of nov 002 a Glutathione Disulfide mimetic
Biomedicine & Pharmacotherapy, 2010Co-Authors: Joachim D Uys, Christopher J Pazoles, Kenneth D Tew, Yefim Manevich, Lindsay Devane, Tracy E Garret, Danyelle M TownsendAbstract:NOV-002 is a Glutathione Disulfide (GSSG) mimetic that is the subject of clinical investigation in oncology indications. GSSG is reduced by Glutathione reductase (GR) to form Glutathione (GSH), thereby maintaining redox homeostasis. The purpose of the study was to report the pharmacokinetic properties of NOV-002 and evaluate the effect that NOV-002 elicits in redox homeostasis. The pharmacokinetic analysis and tissue distribution of NOV-002 and GSH was evaluated in mice following a dose of 250 mg/kg, i.p. The redox potential and total protein thiol status was calculated. Here we show that NOV-002 is a substrate for GR and that GSH is a primary metabolite. Non-linear pharmacokinetic modeling predicted that the estimated absorption and elimination rate constants correspond to a half-life of approximately 13 min with an AUC of 1.18 μgh/mL, a C(max) of 2.16 μg/ml and a volume of distribution of 42.61 L/kg. In addition, measurement of the redox potential and total protein thiol status indicated the generation of a transient oxidative signal in the plasma compartment after administration of NOV-002. These results indicate that NOV-002 exerts kinetic and dynamic effects in mice consistent with the GSSG component as the active pharmacological constituent of the drug. A longer-lasting decrease in total plasma free thiol content was also seen, suggesting that the oxidative effect of the GSSG from NOV-002 was impacting redox homeostasis.
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protective effects of a Glutathione Disulfide mimetic nov 002 against cisplatin induced kidney toxicity
Biomedicine & Pharmacotherapy, 2010Co-Authors: Sara Jenderny, Kenneth D Tew, He Lin, Tracy E Garrett, Danyelle M TownsendAbstract:NOV-002 is a Glutathione Disulfide (GSSG) mimetic with chemoprotective activity. Previous and ongoing clinical studies demonstrate a significantly improved 1-year survival and decreased tumor progression rates in non-small cell lung (NSCLC) and ovarian cancer patients when NOV-002 was included in cisplatin containing regimens. In order to understand this chemoprotective property, we employed as an animal model of kidney toxicity, 8-week-old Bl6 mice that were treated with a single nephrotoxic dose of cisplatin (15 mg/kg, ip) and sacrificed on Day 5. One group of animals was treated with NOV-002 (15 mg/kg, im) daily. NOV-002-treated mice had significantly lower levels of plasma creatinine compared to mice treated with cisplatin alone (4.7 vs 2.9 mg/dL, respectively). Moreover, NOV-002 protected the kidneys from cisplatin mediated proximal tubule damage, including dilation of tubules and the presence of protein casts. Since cisplatin-induced nephrotoxicity can be mediated by a Glutathione-platinum conjugate catalyzed by γ-glutamyl-transpeptidase (GGT) and Glutathione is an endogenous substrate of GGT, the protective effect of NOV-002 in the kidney may be attributed to its ability to act as a competitive substrate for the enzyme.
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nov 002 a mimetic of Glutathione Disulfide
Expert Opinion on Investigational Drugs, 2008Co-Authors: Danyelle M Townsend, Christopher J Pazoles, Kenneth D TewAbstract:Background: Oxidative signaling to modulate redox-sensitive cell functions is a heretofore unexploited approach to developing new drugs for poorly treated oncology indications, where current therapies are often only palliative and accompanied by severe toxicities. Objective: Clinical and non-clinical findings with NOV-002 (a mimetic of Glutathione Disulfide that represents such an approach) are reviewed and evaluated. Methods: Published data on NOV-002 along with unpublished information from the drug's sponsor were reviewed. Literature analysis also focused on protein S-glutathionylation as a regulatory mechanism, particularly in relation to cell signaling, proliferation and cytoskeletal architecture. Results/conclusion: NOV-002 is a mechanistically novel agent with potential for ameliorating hematologic toxicity and enhancing efficacy when used in combination with standard chemotherapy to treat cancer patients.
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nov 002 a Glutathione Disulfide mimetic as a modulator of cellular redox balance
Cancer Research, 2008Co-Authors: Danyelle M Townsend, Christopher J Pazoles, Tracy E Garrett, Steven Hutchens, Kenneth D TewAbstract:NOV-002 is a novel Glutathione Disulfide mimetic that when administered in combination with standard chemotherapeutic regimens has resulted in increased efficacy (survival, tumor response) and improved tolerance to chemotherapy (e.g., hematologic recovery) in advanced non–small cell lung cancer patients. We show that NOV-002, which is not cytotoxic as a single agent, generated time- and concentration-dependent oxidative signals at the cell surface (reduction in protein thiols) and intracellularly [altered oxidized Glutathione (GSSG) and reduced Glutathione levels and ratio; increased reactive oxygen species] in the premyeloid HL-60 cell line and that this was associated with an increase in S-glutathionylation of cell proteins, particularly actin. Commensurate with these effects, NOV-002 activated p38, c-Jun-NH2-kinase, and extracellular signal-regulated kinase and caused a dosedependent increase in phosphorylation of three proteins that have previously been linked with hematopoiesis, AKT, JAK2, and STAT5. The effect of NOV-002 on enzymes involved in Glutathione metabolism was evaluated. Relative to oxidized Glutathione, NOV-002 was an equivalent substrate for Glutathione reductase and was an inhibitor of protein Disulfide isomerase, one of the components of the redox-sensitive unfolded protein response pathway. These redox-stimulated cell signaling actions occurred in the context of increased HL-60 cell proliferation after treatment with NOV-002. Overall, the pleiotropic pharmacologic effects of NOV-002 can be attributed to the GSSG component of the drug, and modulation of cellular redox balance is a feature central to the mechanism of action of NOV-002. Such modulation may underlie its clinical actions, including hematologic recovery and immunostimulation in the face of chemosuppression. [Cancer Res 2008;68(8):2870–7]
Garry R Buettner - One of the best experts on this subject based on the ideXlab platform.
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redox environment of the cell as viewed through the redox state of the Glutathione Disulfide Glutathione couple
Free Radical Biology and Medicine, 2001Co-Authors: Freya Q Schafer, Garry R BuettnerAbstract:Redox state is a term used widely in the research field of free radicals and oxidative stress. Unfortunately, it is used as a general term referring to relative changes that are not well defined or quantitated. In this review we provide a definition for the redox environment of biological fluids, cell organelles, cells, or tissue. We illustrate how the reduction potential of various redox couples can be estimated with the Nernst equation and show how pH and the concentrations of the species comprising different redox couples influence the reduction potential. We discuss how the redox state of the Glutathione Disulfide-Glutathione couple (GSSG/2GSH) can serve as an important indicator of redox environment. There are many redox couples in a cell that work together to maintain the redox environment; the GSSG/2GSH couple is the most abundant redox couple in a cell. Changes of the half-cell reduction potential (E hc )o f the GSSG/2GSH couple appear to correlate with the biological status of the cell: proliferation E hc '2 240 mV; differentiation E hc '2 200 mV; or apoptosis Ehc '2 170 mV. These estimates can be used to more fully understand the redox biochemistry that results from oxidative stress. These are the first steps toward a new quantitative biology, which hopefully will provide a rationale and understanding of the cellular mechanisms associated with cell growth and development, signaling, and reductive or oxidative stress. © 2001 Elsevier Science Inc. Keywords—Glutathione, NADPH, Nernst equation, Reduction potentials, Free radicals
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redox environment of the cell as viewed through the redox state of the Glutathione Disulfide Glutathione couple
Free Radical Biology and Medicine, 2001Co-Authors: Freya Q Schafer, Garry R BuettnerAbstract:Abstract Redox state is a term used widely in the research field of free radicals and oxidative stress. Unfortunately, it is used as a general term referring to relative changes that are not well defined or quantitated. In this review we provide a definition for the redox environment of biological fluids, cell organelles, cells, or tissue. We illustrate how the reduction potential of various redox couples can be estimated with the Nernst equation and show how pH and the concentrations of the species comprising different redox couples influence the reduction potential. We discuss how the redox state of the Glutathione Disulfide-Glutathione couple (GSSG/2GSH) can serve as an important indicator of redox environment. There are many redox couples in a cell that work together to maintain the redox environment; the GSSG/2GSH couple is the most abundant redox couple in a cell. Changes of the half-cell reduction potential (E hc ) of the GSSG/2GSH couple appear to correlate with the biological status of the cell: proliferation E hc ≈ −240 mV; differentiation E hc ≈ −200 mV; or apoptosis E hc ≈ −170 mV. These estimates can be used to more fully understand the redox biochemistry that results from oxidative stress. These are the first steps toward a new quantitative biology, which hopefully will provide a rationale and understanding of the cellular mechanisms associated with cell growth and development, signaling, and reductive or oxidative stress.
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redox environment of the cell as viewed through the redox state of the Glutathione Disulfide Glutathione couple
Free Radical Biology and Medicine, 2001Co-Authors: Freya Q Schafer, Garry R BuettnerAbstract:Redox state is a term used widely in the research field of free radicals and oxidative stress. Unfortunately, it is used as a general term referring to relative changes that are not well defined or quantitated. In this review we provide a definition for the redox environment of biological fluids, cell organelles, cells, or tissue. We illustrate how the reduction potential of various redox couples can be estimated with the Nernst equation and show how pH and the concentrations of the species comprising different redox couples influence the reduction potential. We discuss how the redox state of the Glutathione Disulfide-Glutathione couple (GSSG/2GSH) can serve as an important indicator of redox environment. There are many redox couples in a cell that work together to maintain the redox environment; the GSSG/2GSH couple is the most abundant redox couple in a cell. Changes of the half-cell reduction potential (E(hc)) of the GSSG/2GSH couple appear to correlate with the biological status of the cell: proliferation E(hc) approximately -240 mV; differentiation E(hc) approximately -200 mV; or apoptosis E(hc) approximately -170 mV. These estimates can be used to more fully understand the redox biochemistry that results from oxidative stress. These are the first steps toward a new quantitative biology, which hopefully will provide a rationale and understanding of the cellular mechanisms associated with cell growth and development, signaling, and reductive or oxidative stress.