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Gong C, Qiao L, Feng R, Xu Q, Zhang Y, Fang Z, Shen J, Li S. IL-6-induced acetylation of E2F1 aggravates oxidative damage of retinal pigment epithelial cell line. Exp Eye Res 2020; 200:108219. [PMID: 32910941 DOI: 10.1016/j.exer.2020.108219] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 08/23/2020] [Accepted: 09/03/2020] [Indexed: 01/27/2023]
Abstract
Oxidative damage in retinal pigment epithelial cells (RPE) is considered to be a crucial pathogenesis of age-related macular degeneration (AMD). Although dysregulation of the DNA repair system has been found in RPE cells of AMD patients, the detailed molecular mechanisms of this dysregulation and their relationship with the intraocular microenvironment of AMD patients remain unclear. Here, we established an RPE model of H2O2-induced oxidative stress and found that Sirtuin 1 (Sirt1)-mediated deacetylation of E2F transcription factor 1 (E2F1) was required for oxidation resistance in RPE cells. Moreover, E2F1 induced the expression of the chromatin-binding protein, high mobility group AT-Hook 1 (HMGA1), which promoted the transcription of glucose 6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the pentose phosphate pathway, to increase NADPH level for antioxidant defense. Interrupting the E2F1/HMGA1/G6PD regulatory axis increased reactive oxygen species (ROS) levels, DNA damage, and apoptosis in RPE cells under oxidative stress. Notably, interleukin 6 (IL-6), an inflammatory cytokine that is known to be upregulated in the intraocular fluid of AMD patients, induced phosphorylation (S47) of Sirt1 by activating PI3K/AKT/mTOR signaling, thereby inhibiting Sirt1 activity and increasing the acetylation of E2F1. Specific inhibitors of PI3K/AKT/mTOR signaling decreased DNA damage and ROS while increasing NADPH in RPE cells. Collectively, our findings demonstrate that IL-6-induced acetylation of E2F1 impairs the antioxidant capacity of RPE cells by disturbing the pentose phosphate pathway, which elucidates a relationship between the intraocular microenvironment and RPE oxidative damage in AMD and provides a possible therapeutic target for AMD.
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Affiliation(s)
- Chaoju Gong
- Xuzhou Key Laboratory of Ophthalmology, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China
| | - Lei Qiao
- Xuzhou Key Laboratory of Ophthalmology, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China
| | - Ruifang Feng
- Xuzhou Key Laboratory of Ophthalmology, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China
| | - Qing Xu
- Xuzhou Key Laboratory of Ophthalmology, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China
| | - Yipeng Zhang
- Xuzhou Key Laboratory of Ophthalmology, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China
| | - Zejun Fang
- Central Laboratory, Sanmen People's Hospital of Zhejiang, Sanmenwan Branch of the First Affiliated Hospital, College of Medicine, Zhejiang University, Sanmen, 317100, China
| | - Jie Shen
- Department of Nursing, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China.
| | - Suyan Li
- Xuzhou Key Laboratory of Ophthalmology, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China; Department of Ophthalmology, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou First People's Hospital, Eye Institute of Xuzhou, Xuzhou, 221100, China.
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2
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DuHadaway J, Prendergast GC. Antimetabolite TTL-315 selectively kills glucose-deprived cancer cells and enhances responses to cytotoxic chemotherapy in preclinical models of cancer. Oncotarget 2016; 7:7372-80. [PMID: 26840263 PMCID: PMC4884924 DOI: 10.18632/oncotarget.7058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 01/23/2016] [Indexed: 11/26/2022] Open
Abstract
Maintaining thiol homeostasis is an imperative for cancer cell survival in the nutrient-deprived microenvironment of solid tumors. Despite this metabolic vulnerability, a selective approach has yet to be developed to disrupt thiol homeostasis in solid tumors for therapeutic purposes. In this study, we report the identification of 2-mercaptopropionyl glycine disulfide (TTL-315) as a novel antimetabolite that blocks cell survival in a manner conditional on glucose deprivation. In the presence of glucose, TTL-315 lacks cytotoxic effects in normal cells where it is detoxified by reduction to 2-mercaptopropionyl glycine, a compound with known clinical pharmacologic and safety profiles. In several rodent models of aggressive breast, lung and skin cancers, TTL-315 blocked tumor growth and cooperated with the DNA damaging drug cisplatin to trigger tumor regression. Our results offer preclinical proof of concept for TTL-315 as a novel antimetabolite to help selectively eradicate solid tumors by exploiting the glucose-deprived conditions of the tumor microenvironment.
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Affiliation(s)
| | - George C Prendergast
- Lankenau Institute for Medical Research, Wynnewood, PA, USA.,Sidney Kimmel Cancer Center and Department of Pathology, Anatomy and Cell Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelpia, PA, USA
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3
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Abstract
Solar UVB is carcinogenic. Nucleotide excision repair (NER) counteracts the carcinogenicity of UVB by excising potentially mutagenic UVB-induced DNA lesions. Despite this capacity for DNA repair, non-melanoma skin cancers and apparently normal sun-exposed skin contain huge numbers of mutations that are mostly attributable to unrepaired UVB-induced DNA lesions. UVA is about 20-times more abundant than UVB in incident sunlight. It does cause some DNA damage but this does not fully account for its biological impact. The effects of solar UVA are mediated by its interactions with cellular photosensitizers that generate reactive oxygen species (ROS) and induce oxidative stress. The proteome is a significant target for damage by UVA-induced ROS. In cultured human cells, UVA-induced oxidation of DNA repair proteins inhibits DNA repair. This article addresses the possible role of oxidative stress and protein oxidation in determining DNA repair efficiency - with particular reference to NER and skin cancer risk.
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Affiliation(s)
- Peter Karran
- Francis Crick Research Institute, Clare Hall Laboratory, South Mimms, Herts. EN6 3LD, UK.
| | - Reto Brem
- Francis Crick Research Institute, Clare Hall Laboratory, South Mimms, Herts. EN6 3LD, UK
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Li J, Zhang D, Jefferson PA, Ward KM, Ayene IS. A bioactive probe for glutathione-dependent antioxidant capacity in breast cancer patients: implications in measuring biological effects of arsenic compounds. J Pharmacol Toxicol Methods 2013; 69:39-48. [PMID: 24149024 DOI: 10.1016/j.vascn.2013.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 10/08/2013] [Accepted: 10/10/2013] [Indexed: 01/17/2023]
Abstract
INTRODUCTION Glutathione, a major cellular non-protein thiol (NPSH), serves a central role in repairing damage induced by cancer drugs, pollutants and radiation and in the detoxification of several cancer chemotherapeutic drugs and toxins. Current methods measure glutathione levels only, which require cellular extraction, rather than the glutathione recycling dependent antioxidant activity in intact cells. Here, we present a novel method using a bioactive probe of the oxidative pentose phosphate cycle, termed the OxPhos™ test, to quantify glutathione recycling dependent antioxidant activity in whole blood and intact human and rodent cells without the need for the isolation and cytoplasm extraction of cells. METHODS OxPhos™ test kit (Rockland Immunochemicals, USA), which uses hydroxyethyldisulfide (HEDS) as a probe for the oxidative pentose phosphate cycle, was used in these studies. The results with OxPhos™ test kit in human blood and intact cells were compared with total thiol and high pressure liquid chromatography/electrochemical detection of HEDS metabolism. RESULTS The OxPhos™ test measured glutathione-dependent antioxidant activity both in intact human and rodent cells and breast cancer patient's blood with a better correlation coefficient and biological variability than the thiol assay. Additionally, human blood and mammalian cells treated with various arsenicals showed a concentration-dependent decrease in activity. DISCUSSION The results demonstrate the application of this test for measuring the antioxidant capacity of blood and the effects of environmental pollutants/toxins. It opens up new avenues for an easy and reliable assessment of glutathione-dependent antioxidant capacity in various diseases such as stroke, blood borne diseases, infection, cardiovascular disease and other oxidative stress related diseases and as a prognostic indicator of chemotherapy response and toxicity. The use of this approach in pharmacology/toxicology including screening drugs that improve the glutathione-dependent antioxidant capacity and not just the glutathione level is clinically relevant since mammalian cells require glutathione dependent pathways for antioxidant activity.
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Affiliation(s)
- Jie Li
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA
| | - Donglan Zhang
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA
| | - Pearl A Jefferson
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA; Department of Biological Sciences, Drexel University, Philadelphia, PA 19104, USA
| | - Kathleen M Ward
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA
| | - Iraimoudi S Ayene
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA; Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA.
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5
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Li J, Ward KM, Zhang D, Dayanandam E, Denittis AS, Prendergast GC, Ayene IS. A bioactive probe of the oxidative pentose phosphate cycle: novel strategy to reverse radioresistance in glucose deprived human colon cancer cells. Toxicol In Vitro 2012; 27:367-77. [PMID: 22926048 DOI: 10.1016/j.tiv.2012.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 08/04/2012] [Accepted: 08/07/2012] [Indexed: 11/25/2022]
Abstract
The specific effects of glucose deprivation on oxidative pentose phosphate cycle (OPPC) function, thiol homeostasis, protein function and cell survival remain unclear due to lack of a glucose-sensitive chemical probe. Using p53 wild type and mutant human colon cells, we determined the effects of hydroxyethyl disulfide (HEDS) on NADPH, GSH, GSSG, total glutathione, total non-protein and protein thiol levels, the function of the DNA repair protein Ku, and the susceptibility to radiation-induced free radicals under normal glucose or glucose-deprived conditions. HEDS is rapidly detoxified in normal glucose but triggered a p53-independent metabolic stress in glucose depleted state that caused loss of NADPH, protein and non-protein thiol homeostasis and Ku function, and enhanced sensitivity of both p53 wild type and mutant cells to radiation induced oxidative stress. Additionally, high concentration of HEDS alone induced cell death in p53 wild type cells without significant effect on p53 mutant cells. HEDS offers a useful tool to gain insights into how glucose metabolism affects OPPC dependent stress-induced cellular functions and injury, including in tumor cells, where our findings imply a novel therapeutic approach to target glucose deprived tumor. Our work introduces a novel probe to address cancer metabolism and ischemic pathology.
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Affiliation(s)
- Jie Li
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, PA 19096, USA
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6
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Li J, Zhang D, Ward KM, Prendergast GC, Ayene IS. Hydroxyethyl disulfide as an efficient metabolic assay for cell viability in vitro. Toxicol In Vitro 2012; 26:603-12. [PMID: 22321380 DOI: 10.1016/j.tiv.2012.01.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 01/05/2012] [Accepted: 01/06/2012] [Indexed: 11/25/2022]
Abstract
Cell viability assays have a variety of well known practical and technical limitations. All the available approaches have disadvantages, such as non-linearity, high background and cumbersome protocols. Several commonly used tetrazolium chemicals rely upon generation of a colored formazan product formed by mitochondrial reduction of these compounds via phenazine methosulfate (PMS). However, sensitivity is inherently limited because their reduction relies on mitochondrial bioreduction and cellular transport of PMS, as well as accessibility to tetrazolium chemicals. In this study, we identify hydroxethyldisulfide (HEDS) as an inexpensive probe that can measure cellular metabolic activity without the need of PMS. In tissue culture medium, HEDS accurately quantitated metabolically active live cells in a linear manner superior to tetrazolium based and other assays. Cell toxicity produced by chemotherapeutics (cisplatin, etoposide), oxidants (hydrogen peroxide, acetaminophen), toxins (phenyl arsine oxide, arsenite) or ionizing radiation was rapidly determined by the HEDS assay. We found that HEDS was superior to other commonly used assays for cell viability determinations in its solubility, membrane permeability, and intracellular conversion to a metabolic reporter that is readily transported into the extracellular medium. Our findings establish the use of HEDS in a simple, rapid and low cost assay to accurately quantify viable cells.
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Affiliation(s)
- Jie Li
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, PA 19096, USA
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7
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ATM activates the pentose phosphate pathway promoting anti-oxidant defence and DNA repair. EMBO J 2010; 30:546-55. [PMID: 21157431 PMCID: PMC3034007 DOI: 10.1038/emboj.2010.330] [Citation(s) in RCA: 306] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 11/23/2010] [Indexed: 02/03/2023] Open
Abstract
The DNA damage-induced ATM kinase is linked to the metabolic pentose phosphate pathway, thus boosting biosynthesis of nucleotide precursors required for DNA repair and stimulating generation of the anti-oxidant NADPH, which may explain neurological defects of ataxia telangiectasia patients lacking ATM function. Ataxia telangiectasia (A-T) is a human disease caused by ATM deficiency characterized among other symptoms by radiosensitivity, cancer, sterility, immunodeficiency and neurological defects. ATM controls several aspects of cell cycle and promotes repair of double strand breaks (DSBs). This probably accounts for most of A-T clinical manifestations. However, an impaired response to reactive oxygen species (ROS) might also contribute to A-T pathogenesis. Here, we show that ATM promotes an anti-oxidant response by regulating the pentose phosphate pathway (PPP). ATM activation induces glucose-6-phosphate dehydrogenase (G6PD) activity, the limiting enzyme of the PPP responsible for the production of NADPH, an essential anti-oxidant cofactor. ATM promotes Hsp27 phosphorylation and binding to G6PD, stimulating its activity. We also show that ATM-dependent PPP stimulation increases nucleotide production and that G6PD-deficient cells are impaired for DSB repair. These data suggest that ATM protects cells from ROS accumulation by stimulating NADPH production and promoting the synthesis of nucleotides required for the repair of DSBs.
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8
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Ayene IS, Biaglow JE, Kachur AV, Stamato TD, Koch CJ. Mutation in G6PD gene leads to loss of cellular control of protein glutathionylation: mechanism and implication. J Cell Biochem 2008; 103:123-35. [PMID: 17516514 DOI: 10.1002/jcb.21394] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
More than 400 million people are susceptible to oxidative stress due to glucose-6-phosphate dehydrogenase (G6PD) deficiency. Protein glutathionylation is believed to be responsible for loss of protein function and/or cellular signaling during oxidative stress. To elucidate the implications of G6PD deficiency specifically in cellular control of protein glutathionylation, we used hydroxyethyldisulfide (HEDS), an oxidant which undergoes disulfide exchange with existing thiols. G6PD deficient (E89) cells treated with HEDS showed a significant increase in protein glutathionylation compared to wild-type (K1) cells. In order to determine whether increase in global protein glutathionylation by HEDS leads to loss of function of an important protein, we compared the effect of HEDS on global protein glutathionylation with that of Ku protein function, a multifunctional DNA repair protein, using a novel ELISA. E89 cells treated with HEDS showed a significant loss of Ku protein binding to DNA. Cellular protein thiol and GSH, whose disulfide is involved in protein glutathionylation, were decreased by HEDS in E89 cells with no significant effect in K1 cells. E89 cells showed lower detoxification of HEDS, that is, conversion of disulfide HEDS to free sulfhydryl mercaptoethanol (ME), compared to K1 cells. K1 cells maintained their NADH level in the presence of HEDS but that of E89 cells decreased by tenfold following a similar exposure. NADPH, a cofactor required to maintain reduced form of the thiols, was decreased more in E89 than K1 cells. The specific role of G6PD in the control of such global protein glutathionylation and Ku function was further demonstrated by reintroducing the G6PD gene into E89 (A1A) cells, which showed a normal phenotype.
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Affiliation(s)
- Iraimoudi S Ayene
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, PA 19096, USA.
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9
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Andrews BJ, Lehman JA, Turchi JJ. Kinetic analysis of the Ku-DNA binding activity reveals a redox-dependent alteration in protein structure that stimulates dissociation of the Ku-DNA complex. J Biol Chem 2006; 281:13596-13603. [PMID: 16537541 PMCID: PMC2432111 DOI: 10.1074/jbc.m512787200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ku is a heterodimeric protein comprising 70- and 80-kDa subunits that participate in the non-homologous end-joining (NHEJ) repair pathway for rejoining DNA double strand breaks. We have analyzed the pre-steady state binding of Ku with various DNA duplex substrates and identified a redox-sensitive Ku-DNA interaction. Pre-steady state analysis of Ku DNA binding was monitored via intrinsic Ku quenching upon binding DNA and revealed that, under fully reduced conditions, binding occurred in a single-step process. Reactions performed under limited reduction revealed a two-step binding process, whereas under fully oxidized conditions, we were unable to detect quenching of Ku fluorescence upon binding DNA. The differential quenching observed under the different redox conditions could not be attributed to two Ku molecules binding to a single substrate or Ku sliding inward on the substrate. Although only modest differences in Ku DNA binding activity were observed in the stoichiometric anisotropy and electrophoretic mobility shift assay studies, as a function of redox conditions, a dramatic difference in the rate of Ku dissociation from DNA was observed. This effect was also induced by diamide treatment of Ku and could be abrogated by dithiothreitol treatment, demonstrating a reversible redox effect on the stability of the Ku-DNA complex. The redox-dependent alteration in Ku-DNA interactions is manifested by a redox-dependent alteration in Ku structure, which was confirmed by limited proteolysis and mass spectrometry analyses. The results support a model for the interaction of Ku with DNA that is regulated by redox status and is achieved by altering the dissociation of the Ku-DNA complex.
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Affiliation(s)
- Brooke J Andrews
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Jason A Lehman
- Department of Biomedical Sciences, Wright State University, Dayton, Ohio 45435
| | - John J Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202.
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Biaglow JE, Ayene IS, Tuttle SW, Koch CJ, Donahue J, Mieyal JJ. Role of vicinal protein thiols in radiation and cytotoxic responses. Radiat Res 2006; 165:307-17. [PMID: 16494519 DOI: 10.1667/rr3505.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Glutathione (GSH) and more recently protein thiols (P-SH) have been found to play a major role in cellular radiation response. However, the effects of protein vicinal thiols, which are important for the functions of several major enzymes, on cellular responses to radiation have not been clearly delineated. Here we investigated the effects of depleting GSH and protein vicinal thiols (HS-P-SH) and P-SH on cell toxicity and radiation response. We used hydroxyethyldisulfide (HEDS, beta-mercaptoethanol-disulfide) alone and in combination with phenylarsine oxide (PAO) to alter P-SH, HS-P-SH and GSH. HEDS, a direct substrate for thioredoxin reductase and an indirect substrate for glutaredoxin (thioltransferase), did not alter protein vicinal thiols in cells. However, PAO, which specifically forms a covalent adduct with vicinal thiols, blocked bioreduction of HEDS; there was a concomitant and yet unexplained decrease in K1 cell GSH in the presence of HEDS and PAO. G6PD+ (K1) and G6PD- (E89) cells treated with L-buthionine sulfoximine (L-BSO) for 72 h to deplete GSH followed by PAO showed an increased cytotoxic response. However, the surviving E89 cells showed a 10,000-fold greater radiation lethality than the K1 cells. The effects of rapid depletion of GSH by a combination of L-BSO and dimethyfumarate (DMF), a glutathione-S-transferase substrate, were also investigated. Under these conditions, PAO radiosensitized the E89 cells more than 1000-fold over the K1 cells. The potential mechanisms for the altered response may be related to the inhibition of thioredoxin reductase and glutaredoxin. Both are key enzymes involved in DNA synthesis, protein homeostasis and cell survival. With GSH removed, vicinal thiols appear to play a critical role in determining cell survival and radiosensitivity. Decreasing P-SH and removing GSH and vicinal thiols is extremely toxic to K1 and E89 cells. We conclude that radiation sensitivity and cell survival are dependent on vicinal thiol and GSH. In the former and latter cases, the protein thiols are also important.
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Affiliation(s)
- John E Biaglow
- Department of Biochemistry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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11
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Koukourakis MI, Maltezos E. Amifostine administration during radiotherapy for cancer patients with genetic, autoimmune, metabolic and other diseases. Anticancer Drugs 2006; 17:133-8. [PMID: 16428930 DOI: 10.1097/00001813-200602000-00003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Amifostine is a broad-spectrum cytoprotective agent approved for protection against cisplatin toxicities and radiation-induced xerostomia; strong clinical evidence exists that amifostine protects normal mucosa and lung from radiation damage. Hypotension, nausea/vomiting, fatigue and fever/rash are the main side-effects associated with amifostine administration. The present study summarizes our experience on daily amifostine administration to cancer patients with various coexisting medical conditions and diseases. The tolerance and the eventual interference of amifostine with the course of the coexisting diseases is reported, providing a core list of medical conditions met in radiotherapy practice, their compatibility with amifostine administration and recommendations on how to deal with these patients. This list comprises genetic diseases (xeroderma pigmentosum, glucose-6-phosphate dehydrogenase deficiency), autoimmune disorders (vitiligo, scleroderma, thyroiditis, perforating collagenosis), metabolic diseases (diabetes mellitus), cardiovascular diseases, neuro/psychiatric diseases and other medical conditions (hypoglycemia, hepatic cirrhosis, alcoholism). A high incidence of fever/rash was noted in patients with autoimmune diseases, while all other conditions did not alter the patterns of side-effects expected following amifostine administration.
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Affiliation(s)
- Michael I Koukourakis
- Department of Radiotherapy/Oncology, Democritus University of Thrace, Alexandroupolis, Greece.
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12
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Ayene IS, Ford LP, Koch CJ. Ku protein targeting by Ku70 small interfering RNA enhances human cancer cell response to topoisomerase II inhibitor and gamma radiation. Mol Cancer Ther 2005; 4:529-36. [PMID: 15827325 DOI: 10.1158/1535-7163.mct-04-0130] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ku protein is a heterodimer (Ku70 and Ku86) known to play an important role in V(D)J recombination, apoptosis, telomere fusion, and double-strand break repair. Its role in double-strand breaks is relevant to cancer therapy because lack of Ku86 causes one of the most radiation-responsive phenotypes (hamster cells, XRS5). Although it is known that the heterodimer is necessary for the various functions of this protein, the impact of targeting Ku in human cancer cells has not been shown due to lack of appropriate approaches. It is also not known whether complete knock-out of Ku protein is required to enhance the sensitivity of human cells to gamma radiation as Ku protein is much more abundant in human cells than in hamster cells. In the current article, we have investigated the direct effect of Ku70 depletion in human cervical epithelioid (HeLa) and colon carcinoma (HCT116) cells. We specifically targeted Ku70 mRNA by use of small interfering RNA (siRNA). Of the five Ku70 siRNA synthesized, three inhibited the expression of Ku70 by up to 70% in HeLa cells. We have tested the effect of chemically synthesized siRNAs for target sequence 5 (CS #5) on the response of HeLa cells 72 hours after transfection to gamma radiation and etoposide, as this showed the maximum inhibition of Ku70 expression. Ku70 siRNA induced a decrease in the surviving fraction of irradiated HeLa cells by severalfold. Similar sensitizing effects were observed for etoposide, a topoisomerase II inhibitor. Studies with HCT116 cells using the same Ku70 siRNA (CS #5) showed a direct correlation between expression of Ku70 and sensitization to radiation and etoposide treatments.
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MESH Headings
- Animals
- Antigens, Nuclear/genetics
- Antigens, Nuclear/metabolism
- Antineoplastic Agents, Phytogenic/pharmacology
- Apoptosis
- Blotting, Western
- Cell Line, Tumor
- Cricetinae
- DNA Damage
- DNA Repair
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Dimerization
- Dose-Response Relationship, Radiation
- Etoposide/pharmacology
- Gamma Rays
- HeLa Cells
- Humans
- Ku Autoantigen
- Microscopy, Fluorescence
- Neoplasms/therapy
- Phenotype
- RNA, Messenger/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Telomere/ultrastructure
- Time Factors
- Topoisomerase II Inhibitors
- Transfection
- VDJ Recombinases/metabolism
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Affiliation(s)
- Iraimoudi S Ayene
- Department of Radiation Oncology, School of Medicine, University of Pennsylvania, 195 John Morgan Building, Philadelphia, PA 19104-6072, USA.
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Pavel S, Smit NP, van der Meulen H, Kolb RM, de Groot AJ, van der Velden PA, Gruis NA, Bergman W. Homozygous germline mutation of CDKN2A/p16 and glucose-6-phosphate dehydrogenase deficiency in a multiple melanoma case. Melanoma Res 2003; 13:171-8. [PMID: 12690301 DOI: 10.1097/00008390-200304000-00010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
CDKN2A is regarded as a major melanoma susceptibility gene. A 19 bp deletion has been detected within Dutch families with familial atypical multiple mole-melanoma syndrome. Genetic analysis revealed two individuals with germline deletions in both copies of CDKN2A. One of them did not develop atypical naevi or melanoma, but died of adenocarcinoma at the age of 54 years. This report describes the results of the investigation of the second p16-null individual, who was also found to have glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and who has developed many atypical naevi and seven melanomas. Using electron microscopic techniques, striking alterations in melanosomal structures and deviations in their sulphur, iron and calcium composition indicating a strong preference for phaeomelanogenesis and increased oxidative stress were found in the naevus cells of the patient. Using an in vitro model, we demonstrated that leaking melanin precursors may strongly enhance oxidative DNA damage through iron release from ferritin. We conclude that the homozygous p16 deletion is not sufficient for the development of a dysplastic naevus phenotype and melanoma. However, when an additional modifying factor, such as G-6-PD deficiency, increases the level of oxidative DNA damage in melanin-producing cells, the risk of developing atypical naevi and their malignant transformation may increase significantly.
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Affiliation(s)
- Stan Pavel
- Department of Dermatology, Leiden University Medical Centre, Leiden, The Netherlands. S.
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14
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Biaglow JE, Ayene IS, Koch CJ, Donahue J, Stamato TD, Mieyal JJ, Tuttle SW. Radiation response of cells during altered protein thiol redox. Radiat Res 2003; 159:484-94. [PMID: 12643793 DOI: 10.1667/0033-7587(2003)159[0484:rrocda]2.0.co;2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The major focus of this work was to investigate how altered protein thiol redox homeostasis affects radiation-induced cell death. We used the cells of wild-type CHO cell line K1, the CHO cell line E89, which is null for G6PD activity, and a radiation-sensitive CHO cell line, XRS5. The protein-thiol redox status of cells was altered with cell-permeable disulfides, hydroxyethyldisulfide (HEDS) or lipoate. HEDS is primarily reduced by thioltransferase (glutaredoxin), with GSH as the electron donor. In contrast, lipoate is reduced by thioredoxin reductase. HEDS was reduced at a greater rate than lipoate by G6PD-containing K1 (wild-type) cells. Reduction of disulfides by G6PD-deficient cells was significantly slower with HEDS as substrate and was nearly absent with lipoate. The rate of reduction of HEDS by E89 cells decelerated to near zero by 30 min, whereas the reduction continued at nearly the same rate during the entire measurement period for K1 cells. HEDS treatment decreased the GSH and protein thiol (PSH) content more in G6PD-deficient cells than in G6PD-containing cells. On the other hand, lipoate did not significantly alter the protein thiol, but it increased the GSH in K1 cells. Acute depletion of GSH by l-buthionine-sulfoximine (l-BSO) in combination with dimethylfumarate significantly decreased the rate of reduction of HEDS by K1 cells close to that of G6PD-deficient cells. Prior GSH depletion by l-BSO alone significantly decreased the PSH in glucose-depleted E89 cells exposed to HEDS, but this did not occur with K1 cells. The radiation response of G6PD-deficient cells was significantly sensitized by HEDS, but HEDS did not have this effect on K1 cells. The DNA repair-deficient XRS5 CHO cells displayed the same capacity as K1 cells for HEDS reduction, and like K1 cells the XRS5 cells were not sensitized to radiation by HEDS treatment. Deprivation of glucose, which provides the substrate for G6PD in the oxidative pentose phosphate cycle, decreased the rate of bioreduction of HEDS and lipoate in G6PD-containing cells to the level in G6PD-deficient cells. In the absence of glucose, HEDS treatment diminished non-protein thiol and protein thiol to the same level as those in G6PD-deficient cells and sensitized the K1 cells to HEDS treatment. However, depletion of glucose did not alter the sensitivity of XRS5 cells in either the presence or absence of HEDS. Overall the results suggest a major role for pentose cycle control of protein redox state coupled to the activities of the thioltransferase and thioredoxin systems. The results also show that protein thiol status is a critical factor in cell survival after irradiation.
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Affiliation(s)
- John E Biaglow
- Department of Radiation Oncology and Biochemistry, University of Pennsylvania Medical School, Philadelphia, Pennsylvania 19104, USA.
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Felix K, Rockwood LD, Pretsch W, Bornkamm GW, Janz S. Redox imbalance and mutagenesis in spleens of mice harboring a hypomorphic allele of Gpdx(a) encoding glucose 6-phosphate dehydrogenase. Free Radic Biol Med 2003; 34:226-32. [PMID: 12521604 DOI: 10.1016/s0891-5849(02)01243-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Mice harboring the activity-attenuated Gpdx(a-m2Neu) allele and also harboring a chromosomally integrated lacZ reporter gene to study mutagenesis (pUR288) were used to demonstrate that moderate glucose 6-phosphate dehydrogenase (G6PD) deficiency causes elevated mutagenesis and endogenous oxidative stress in the spleen. G6PD-deficient spleens with a residual enzyme activity of 22% exhibited a dramatic shift in the mutational pattern of lacZ (4.6-fold increase in the prevalence of recombination mutations of lacZ) together with a 1.8-fold increase in mutant frequencies in lacZ. A concomitant 3-fold reduction in catalase activity (dependent upon NADPH) indicated that the in vivo supply of G6PD-generated NADPH was insufficient. An additional 3-fold increase in oxidized glutathione suggested that redox control was disturbed in G6PD-deficient spleens. These findings indicate that G6PD is required for limiting oxidative mutagenesis in the mouse spleen. Gpdx(a-m2Neu) is the first hypomorphic allele of a mouse housekeeping gene associated with elevated somatic mutagenesis in vivo.
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Affiliation(s)
- Klaus Felix
- Laboratory of Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Felix K, Rockwood LD, Pretsch W, Nair J, Bartsch H, Bornkamm GW, Janz S. Moderate G6PD deficiency increases mutation rates in the brain of mice. Free Radic Biol Med 2002; 32:663-73. [PMID: 11909700 DOI: 10.1016/s0891-5849(02)00756-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mice that harbored the x-ray-induced low efficiency allele of the major X-linked isozyme of glucose-6-phospate dehydrogenase (G6PD), Gpdx(a-m2Neu), and, in addition, harbored the transgenic shuttle vector for the determination of mutagenesis in vivo, pUR288, were employed to further our understanding of the interdependence of general metabolism, oxidative stress control, and somatic mutagenesis. The Gpdx(a-m2Neu) mutation conferred moderate G6PD deficiency in hemizygous males (Gpdx(a-m2Neu/y)) displaying residual enzyme activities of 27% in red blood cells and 13% in brain (compared to wild-type controls, Gpdx(a/y) males). In spite of this mild phenotype, the brains of G6PD-deficient males exhibited a significant distortion of redox control ( approximately 3-fold decrease in the ratio of reduced glutathione to oxidized glutathione), a considerable accumulation of promutagenic etheno DNA adducts ( approximately 13-fold increase in ethenodeoxyadenosine and approximately 5-fold increase in ethenodeoxycytidine), and a substantial elevation of somatic mutation rates ( approximately 3-fold increase in mutant frequencies in lacZ, the target and reporter gene of mutagenesis in the shuttle vector, pUR288). The mutation pattern in the brain was dominated by illegitimate genetic recombinations, a presumed hallmark of oxidative mutagenesis. These findings suggested a critical function for G6PD in limiting oxidative mutagenesis in the mouse brain.
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Affiliation(s)
- Klaus Felix
- Laboratory of Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
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Ayene IS, Stamato TD, Mauldin SK, Biaglow JE, Tuttle SW, Jenkins SF, Koch CJ. Mutation in the glucose-6-phosphate dehydrogenase gene leads to inactivation of Ku DNA end binding during oxidative stress. J Biol Chem 2002; 277:9929-35. [PMID: 11788599 DOI: 10.1074/jbc.m111366200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the oxidative pentose phosphate cycle, regulates the NADPH/NADP(+) ratio in eukaryotic cells. G6PD deficiency is one of the most common mutations in humans and is known to cause health problems for hundreds of millions worldwide. Although it is known that decreased G6PD functionality can result in increased susceptibility to oxidative stress, the molecular targets of this stress are not known. Using a Chinese hamster ovary G6PD-null mutant, we previously demonstrated that exposure to a thiol-specific oxidant, hydroxyethyldisulfide, caused enhanced radiation sensitivity and an inability to repair DNA double strand breaks. We now demonstrate a molecular mechanism for these observations: the direct inhibition of DNA end binding activity of the Ku heterodimer, a DNA repair protein, by oxidation of its cysteine residues. Inhibition of Ku DNA end binding was found to be reversible by treatment of the nuclear extract with dithiothreitol, suggesting that the homeostatic regulation of reduced cysteine residues in Ku is a critical function of G6PD and the oxidative pentose cycle. In summary, we have discovered a new layer of DNA damage repair, that of the functional maintenance of repair proteins themselves. In view of the rapidly escalating number of roles ascribed to Ku, these results may have widespread ramifications.
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Affiliation(s)
- Iraimoudi S Ayene
- Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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Magda D, Lepp C, Gerasimchuk N, Lee I, Sessler JL, Lin A, Biaglow JE, Miller RA. Redox cycling by motexafin gadolinium enhances cellular response to ionizing radiation by forming reactive oxygen species. Int J Radiat Oncol Biol Phys 2001; 51:1025-36. [PMID: 11704327 DOI: 10.1016/s0360-3016(01)01810-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PURPOSE To examine the mechanism of radiation enhancement by motexafin gadolinium (Gd-Tex) in vitro. METHODS AND MATERIALS Oxidation of ascorbate and NADPH by Gd-Tex was evaluated in a neutral buffer. Growth inhibition of human uterine cancer cell line MES-SA was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. Clonogenic assays were used to measure radiation response in MES-SA, A549 human lung carcinoma, E89, a CHO cell line variant deficient in glucose-6-phosphate dehydrogenase activity, and murine lymphoma cell lines LYAR and LYAS. RESULTS Gd-Tex catalyzed the oxidation of NADPH and ascorbate under aerobic conditions, forming hydrogen peroxide. Decreased viability was observed in MES-SA cells incubated with Gd-Tex in media containing NADPH or ascorbate. Gd-Tex and ascorbate increased fluorescence in dichlorofluorescin acetate-treated cultures. Synergistic effects on the aerobic radiation response in MES-SA and A549 were seen using Gd-Tex in combination with L-buthionine-(S,R)-sulfoximine (BSO). Incubation with Gd-Tex in the presence of ascorbate increased the aerobic radiation response of E89 and the apoptosis-sensitive B-cell line (LYAS). CONCLUSIONS Gd-Tex sensitizes cells to ionizing radiation by increasing oxidative stress as a consequence of futile redox cycling. Optimization of the concentration of ascorbate (or other reducing species) may be required when evaluating Gd-Tex activity in vitro.
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Affiliation(s)
- D Magda
- Pharmacyclics, Inc., Sunnyvale, CA 94085, USA
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