The Effect of the Radioprotector WR-2721 and WR-1065 on Mitochondrial Lipid Peroxidation

Tretter, László; Rónai, É.; Szabados, Gy.; Hermann, Richard K.; Ando, Akio; Horváth, István

doi:10.1080/09553009014552611

Cited by 12 publications

(4 citation statements)

References 24 publications

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“…Immediate radioprotection of HMEC is the result of the localization of the free thiol WR1065 within two sensitive subcellular targets for radiation damage, the mitochondria and the nuclear DNA compartment [40,41]. If exposure to ionizing radiation occurs at this time, both of these sensitive targets can be protected.…”

Section: Discussionmentioning

confidence: 99%

Delayed radioprotection by nuclear transcription factor κB -mediated induction of manganese superoxide dismutase in human microvascular endothelial cells after exposure to the free radical scavenger WR1065

Murley

Kataoka

Weydert

et al. 2006

Free Radical Biology and Medicine

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The free radical scavenger WR1065 (SH) is the active thiol form of the clinically approved cytoprotector amifostine. At doses of 40 μM and 4 mM it can activate the redox-sensitive nuclear transcription factor κB (NFκB) and elevate the expression of the antioxidant gene manganese superoxide dismutase (MnSOD) in human microvascular endothelial cells (HMEC). MnSOD contains binding motifs for a number of transcription factors other than NFκB and codes for a potent antioxidant enzyme localized in the mitochondria that is known to confer enhanced radiation resistance to cells. The purpose of this study was to determine the effect of WR1065 exposure on the various transcription factors known to affect MnSOD expression along with the subsequent kinetics of intracellular elevation of MnSOD protein levels and associated change in sensitivity to ionizing radiation in HMEC. Cells were grown to confluence and exposed to WR1065 for 30 min. Affects on the transcription factors AP1, AP2, CREB, NFκB, and Sp1 were monitored as a function of time ranging from 30 min to 4 h after drug exposure using a gel-shift assay. Only NFκB exhibited a marked activation and that occurred 30 min following the cessation of drug exposure. MnSOD protein levels, as determined by Western blot analysis, increased up to 16-fold over background control levels by 16 h following drug treatment, and remained at 10-fold or higher levels for an additional 32 h. MnSOD activity was evaluated using a gel-based assay and was found to be active throughout this time period. HMEC were irradiated with X-rays either in the presence of 40 μM or 4 mM WR1065 or 24 h after its removal when MnSOD levels were most elevated. No protection was observed for cells irradiated in the presence of 40 μM WR1065. In contrast, a 4 mM dose of WR1065 afforded an increase in cell survival by a factor of 2. A "delayed radioprotective" effect was, however, observed when cells were irradiated 24 h later, regardless of the concentration of WR1065 used. This effect is characterized as an increase in survival at the 2 Gy dose point, i.e., a 40% increase in survival, and an increase in the initial slope of the survival curve by a factor of 2. The anti-inflammatory sesquiterpene lactone, Helenalin, is an effective inhibitor of NFκB activation. HMEC were exposed to Helenalin for 2 h at a nontoxic concentration of 5 μM prior to exposure to WR1065. This treatment not only inhibited activation of NFκB by WR1065, but also inhibited the subsequent elevation of MnSOD and the delayed radioprotective effect. A persistent marked elevation of MnSOD in cells following their exposure to a thiol-containing reducing agent such as WR1065 can result in an elevated resistance to the cytotoxic effects of ionizing radiation and represents a novel radioprotection paradigm.

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Section: Discussionmentioning

confidence: 99%

Delayed radioprotection by nuclear transcription factor κB -mediated induction of manganese superoxide dismutase in human microvascular endothelial cells after exposure to the free radical scavenger WR1065

Murley

Kataoka

Weydert

et al. 2006

Free Radical Biology and Medicine

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“…In fact, WR-1065 is not generally considered as a GSH inducer. Tretter et al [55] reported that WR-1065 and GSH were effective inhibitors of mitochondrial lipid peroxidation following a redox cycle implicating WR-1065, GSH, and GSH reductase. They suggested that these reactions might prevent the inactivation of mitochondrial enzymes necessary for cell survival.…”

Section: Discussionmentioning

confidence: 99%

Lens epithelial cell protection by aminothiol WR-1065 and anetholedithiolethione from ionizing radiation

Belkacémi¹,

Rat²,

Piel³

et al. 2001

Int. J. Cancer

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SUMMARY Lens epithelium disorganization, glutathione (GSH) depletion, and epithelial cell death have been incriminated in the cytopathogenic mechanisms that lead to cataract formation following UVB and x-ray exposures. The objective of this study was to determine the in vitro capacity of the aminothiol WR-1065, the active metabolite of amifostine, and anetholedithiolethione (ADT or Sulfarlem ) to protect bovine lens epithelial cells against x-ray irradiation. WR-1065 and ADT were used at a concentration of 20 M. A single dose of 10 Gy was delivered at a rate of 2 Gy/min. Fluorimetric assays were then performed using a neutral red probe to evaluate cell viability, a Hoechst 33342 probe (HO) to evaluate nuclear condensation and apoptosis, and a monobromobimane probe to estimate the intracellular GSH pool. Twenty-four hours after x-ray exposure, cells pretreated with WR-1065 showed increased GSH levels, improved cell viability, and decreased HO fluorescence in addition to a lesser proportion of cells with apoptotic nuclear modifications. Between 72 and 120 hr postirradiation, ADT-pretreated cells also showed increased intracellular GSH levels and cell viability and decreased HO fluorescence and apoptotic cell morphology. This in vitro study demonstrates that WR-1065 and ADT protects lens epithelial cells from x-ray injury; thus, ADT and amifostine are appropriate candidates for clinical trials in humans. They are currently used in preventing radiation-induced xerostomia and should be further tested in the prevention of late radiation-induced ocular complications such as sicca syndrome and cataract.

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“…The GSSG is then reduced to GSH by GRd. 39 Protection of the mitochondria can be further facilitated through the development of antioxidants that are designed either for increased uptake into mitochondria, or to increase the activity of antioxidant enzymes. Linking the positively-charged functional group, alkyltriphenyl-phosphonium ion, to vitamin E or ubiquinone (CoQ) increased the uptake of these antioxidants into the mitochondrial matrix.…”

Section: Mitochondriamentioning

confidence: 99%

Antioxidants Reduce Consequences of Radiation Exposure

Okunieff

Swarts

Keng

et al.

Advances in Experimental Medicine and Biology

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Antioxidants have been studied for their capacity to reduce the cytotoxic effects of radiation in normal tissues for at least 50 years. Early research identified sulfur-containing antioxidants as those with the most beneficial therapeutic ratio, even though these compounds have substantial toxicity when given in-vivo. Other antioxidant molecules (small molecules and enzymatic) have been studied for their capacity to prevent radiation toxicity both with regard to reduction of radiation-related cytotoxicity and for reduction of indirect radiation effects including long-term oxidative damage. Finally, categories of radiation protectors that are not primarily antioxidants, including those that act through acceleration of cell proliferation (e.g. growth factors), prevention of apoptosis, other cellular signaling effects (e.g. cytokine signal modifiers), or augmentation of DNA repair, all have direct or indirect effects on cellular redox state and levels of endogenous antioxidants. In this review we discuss what is known about the radioprotective properties of antioxidants, and what those properties tell us about the DNA and other cellular targets of radiation.

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The Effect of the Radioprotector WR-2721 and WR-1065 on Mitochondrial Lipid Peroxidation

Cited by 12 publications

References 24 publications

Delayed radioprotection by nuclear transcription factor κB -mediated induction of manganese superoxide dismutase in human microvascular endothelial cells after exposure to the free radical scavenger WR1065

Delayed radioprotection by nuclear transcription factor κB -mediated induction of manganese superoxide dismutase in human microvascular endothelial cells after exposure to the free radical scavenger WR1065

Lens epithelial cell protection by aminothiol WR-1065 and anetholedithiolethione from ionizing radiation

Antioxidants Reduce Consequences of Radiation Exposure

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