Role of antioxidant enzymes on ionizing radiation resistance

Biomarker dosimetry of acute low level of thermal neutrons and radiation adaptive response effect on rats

In this paper, we demonstrated the biological effects of acute low-dose neutrons on the whole body of rats and investigated the impact of that level of neutron dose to induce an in vivo radio-adaptive response. To understand the radio-adaptive response, the examined animals were exposed to acute neutron radiation doses of 5 and 10 mSv, followed by a 50 mSv challenge dose after 14 days. After irradiation, all groups receiving single and double doses were kept in cages for one day before sampling. The electron paramagnetic resonance (EPR) method was used to estimate the radiation-induced radicals in the blood, and some hematological parameters and lipid peroxidation (MDA) were determined. A comet assay was performed beside some of the antioxidant enzymes [catalase enzyme (CAT), superoxide dismutase (SOD), and glutathione (GSH)]. Seven groups of adult male rats were classified according to their dose of neutron exposure. Measurements of all studied markers are taken one week after harvesting, except for hematological markers, within 2 h. The results indicated lower production of antioxidant enzymes (CAT by 1.18-5.83%, SOD by 1.47-17.8%, and GSH by 11.3-82.1%). Additionally, there was an increase in red cell distribution width (RDW) (from 4.61 to 25.19%) and in comet assay parameters such as Tail Length, (from 6.16 to 10.81 µm), Tail Moment, (from 1.17 to 2.46 µm), and percentage of DNA in tail length (DNA%) (from 9.58 to 17.32%) in all groups exposed to acute doses of radiation ranging from 5 to 50 mSv, respectively. This emphasizes the ascending harmful effect with the increased acute thermal neutron doses. The values of the introduced factor of radio adaptive response for all markers under study reveal that the lower priming dose promotes a higher adaptation response and vice versa. Ultimately, the results indicate significant variations in DNA%, SOD enzyme levels, EPR intensity, total Hb concentration, and RDWs, suggesting their potential use as biomarkers for acute thermal neutron dosimetry. Further research is necessary to validate these measurements as biodosimetry for radiation exposure, including investigations involving the response impact of RAR with varied challenge doses and post-irradiation behavior.

Effects of Hardaliye, a Fermented Grape Drink, on Oxidative Stress, Lipid Profile, and Blood Pressure in Young Soccer Players: A Randomized Controlled Trial

OBJECTIVE

Hardaliye, a traditional fermented grape juice, can prevent imbalances in the antioxidant defense systems of soccer players. Hardaliye is mainly produced through the fermentation of grapes, sour cherry leaves, and mustard seeds and is consumed as a drink. This study was aimed at investigating the effects of hardaliye consumption on oxidative stress parameters, lipid profile, and blood pressure in young elite soccer players.

METHODS

In this single-blind, randomized, placebo-controlled, parallel-design study, while the participants in one of the groups consumed 250 mL/d of hardaliye drink (Hardaliye Group), the participants in the other group consumed placebo drink (Placebo Group) for 28 days. Three-day food record and blood samples were taken from the soccer players and their blood pressure was measured.

RESULTS

Nutrient intakes in both groups were similar at the beginning and end of the study (p > 0.05). Dietary carbohydrates and vitamin A, E, and C intakes were below the recommended levels in both groups. Hardaliye consumption significantly increased the serum total antioxidant capacity level but significantly decreased serum total oxidation status, oxidative stress index, malondialdehyde, and nitric oxide levels compared to the Placebo Group (p < 0.05). Lipid parameters and diastolic blood pressure levels were not significantly different between the groups (p > 0.05). Hardaliye consumption significantly decreased systolic blood pressure compared to that in the Placebo Group (p < 0.05).

CONCLUSION

Hardaliye consumption in young elite soccer players showed antioxidative effects and decreased systolic blood pressure but did not affect their lipid profiles.

Tracing the serendipitous genesis of radiation resistance

Free-living organisms frequently encounter unfavorable abiotic environmental factors. Those who adapt and cope with sudden changes in the external environment survive. Desiccation is one of the most common and frequently encountered stresses in nature. On the contrary, ionizing radiations are limited to high local concentrations of naturally occurring radioactive materials and related anthropogenic activities. Yet, resistance to high doses of ionizing radiation is evident across the tree of life. The evolution of desiccation resistance has been linked to the evolution of ionizing radiation resistance, although, evidence to support the idea that the evolution of desiccation tolerance is a necessary precursor to ionizing radiation resistance is lacking. Moreover, the presence of radioresistance in hyperthermophiles suggests multiple paths lead to radiation resistance. In this minireview, we focus on the molecular aspects of damage dynamics and damage response pathways comprising protective and restorative functions with a definitive survival advantage, to explore the serendipitous genesis of ionizing radiation resistance.

Protective Effects of Alpha-lipoic Acid, Resveratrol, and Apigenin Against Oxidative Damages, Histopathological Changes, and Mortality Induced by Lung Irradiation in Rats

AIM

This study investigated the protective effects of three antioxidants on radiationinduced lung injury.

BACKGROUND

Oxidative stress is one of the key outcomes of radiotherapy in normal tissues. It can induce severe injuries in lung tissue, which may lead to pneumonitis and fibrosis. Recently, interest in natural chemicals as possible radioprotectors has increased due to their reduced toxicity, cheaper price, and other advantages.

OBJECTIVE

The present study was undertaken to evaluate the radioprotective effect of Alpha-lipoic Acid (LA), Resveratrol (RVT), and Apigenin (APG) against histopathological changes and oxidative damage and survival induced by ionizing radiation (IR) in the lung tissues of rats.

METHODS

First, the lung tissue of 50 mature male Wistar rats underwent an 18 Gy gamma irradiation. Next, the rats were sacrificed and transverse sections were obtained from the lung tissues and stained with hematoxylin and eosin (H and E) and Mason trichrome (MTC) for histopathological evaluation. Then, the activity of Glutathione peroxidase (GPx), Superoxide Dismutase (SOD), and Malondialdehyde (MDA) was measured by an ELISA reader at 340, 405, and 550 nm.

RESULTS

Based on the results of this study, IR led to a remarkable increase in morphological changes in the lung. However, APG, RVT, and LA could ameliorate the deleterious effects of IR in lung tissue. IR causes an increase in GPX level, and APG+IR administration causes a decrease in the level of GPX compared to the control group. Also, the results of this study showed that RVT has significant effects in reducing MDA levels in the short term. In addition, compared to the control group, IR and RVT+IR decrease the activity of SOD in the long term in the lung tissues of rats. Also, the analysis of results showed that weight changes in IR, LA+IR, APG+IR, and control groups were statistically significant.

CONCLUSION

APG and RVT could prevent tissue damage induced by radiation effects in rat lung tissues. Hence, APG, LA, and RVT could provide a novel preventive action with their potential antioxidant anti-inflammatory properties, as well as their great safety characteristic.

Radiation-sensitive genetic prognostic model identifies individuals at risk for radiation resistance in head and neck squamous cell carcinoma

BACKGROUND

The advantages of radiotherapy for head and neck squamous cell carcinoma (HNSCC) depend on the radiation sensitivity of the patient. Here, we established and verified radiological factor-related gene signature and built a prognostic risk model to predict whether radiotherapy would be beneficial.

METHODS

Data from The Cancer Genome Atlas, Gene Expression Omnibus, and RadAtlas databases were subjected to LASSO regression, univariate COX regression, and multivariate COX regression analyses to integrate genomic and clinical information from patients with HNSCC. HNSCC radiation-related prognostic genes were identified, and patients classified into high- and low-risk groups, based on risk scores. Variations in radiation sensitivity according to immunological microenvironment, functional pathways, and immunotherapy response were investigated. Finally, the expression of HNSCC radiation-related genes was verified by qRT-PCR.

RESULTS

We built a clinical risk prediction model comprising a 15-gene signature and used it to divide patients into two groups based on their susceptibility to radiation: radiation-sensitive and radiation-resistant. Overall survival was significantly greater in the radiation-sensitive than the radiation-resistant group. Further, our model was an independent predictor of radiotherapy response, outperforming other clinical parameters, and could be combined with tumor mutational burden, to identify the target population with good predictive value for prognosis at 1, 2, and 3 years. Additionally, the radiation-resistant group was more vulnerable to low levels of immune infiltration, which are significantly associated with DNA damage repair, hypoxia, and cell cycle regulation. Tumor Immune Dysfunction and Exclusion scores also suggested that the resistant group would respond less favorably to immunotherapy.

CONCLUSIONS

Our prognostic model based on a radiation-related gene signature has potential for application as a tool for risk stratification of radiation therapy for patients with HNSCC, helping to identify candidates for radiation therapy and overcome radiation resistance.

Pinostrobin alleviates testicular and spermatological damage induced by polystyrene microplastics in adult albino rats

BACKGROUND

Polystyrene microplastics (PS-MPs) have become major environmental pollutants that adversely effects multiple organs specifically testicles. Pinostrobin (PN) is an important flavonoid which, shows several pharmacological potentials.

PURPOSE

The current study was designed to elucidate the mitigative effects of PN against PS-MPs induced testicular toxicities in rats.

METHODS

48 male albino rats were randomly distributed into 4 groups, control, PS-MPs group (0.01 mg/kg), PS-MPs + PN group (0.01 mg/kg of PS-MPs; 40 mg/kg of PN) and PN group (40 mg/kg).

RESULTS

PS-MPs intoxication substantially lessened the activities of glutathione peroxidase (GPx), glutathione reductase (GSR), superoxide dismutase (SOD) along with catalase (CAT) while, raised the level of malondialdehyde (MDA) as well as reactive oxygen species (ROS). Additionally, PS-MPs reduced luteinizing hormone (LH), plasma testosterone, follicle-stimulating hormone (FSH) concentration, sperm motility, sperm count, expression of steroidogenic enzymes and Bcl-2 (anti-apoptotic protein) along with the count of spermatogenic cells. While, dead sperm count, sperm abnormalities (tail, neck and head), Bax and caspase-3 (apoptotic proteins) expression along with histopathological anomalies were elevated. Moreover, PS-MPs exposure increased the level of inflammatory markers. However, PN treatment considerably decreased oxidative stress (OS) by reducing ROS as well as increased sperm motility and alleviated all the damages induced by the PS-MPs.

CONCLUSION

Therefore, it is concluded that PN may prove a potential therapeutic candidate to restore all the PS-MPs-induced testicular toxicities.

Radioresistance in rhabdomyosarcomas: Much more than a question of dose

Management of rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children, frequently accounting the genitourinary tract is complex and requires a multimodal therapy. In particular, as a consequence of the advancement in dose conformity technology, radiation therapy (RT) has now become the standard therapeutic option for patients with RMS. In the clinical practice, dose and timing of RT are adjusted on the basis of patients' risk stratification to reduce late toxicity and side effects on normal tissues. However, despite the substantial improvement in cure rates, local failure and recurrence frequently occur. In this review, we summarize the general principles of the treatment of RMS, focusing on RT, and the main molecular pathways and specific proteins involved into radioresistance in RMS tumors. Specifically, we focused on DNA damage/repair, reactive oxygen species, cancer stem cells, and epigenetic modifications that have been reported in the context of RMS neoplasia in both in vitro and in vivo studies. The precise elucidation of the radioresistance-related molecular mechanisms is of pivotal importance to set up new more effective and tolerable combined therapeutic approaches that can radiosensitize cancer cells to finally ameliorate the overall survival of patients with RMS, especially for the most aggressive subtypes.

The Influence of MicroRNA-31 on Oxidative Stress and Radiosensitivity in Pancreatic Ductal Adenocarcinoma

Radioresistance remains a significant challenge in treating pancreatic ductal adenocarcinoma (PDAC), contributing to the poor survival rates of this cancer. MicroRNAs (miRs) are small non-coding RNA molecules that may play an essential role in regulating radioresistance by altering the levels of oxidative stress. In this study, we investigated the role and potential mechanisms linking miR-31 to PDAC radioresistance. A pCMV-miR vector containing a miR-31 mimic was stably expressed into a miR-31-deficient PDAC cell line, BxPC-3. Additionally, a pmiRZip lentivector suppressing miR-31 was stably expressed in a miR-31 abundant PDAC cell line, Panc-1. Clonogenic assays were conducted to explore the role of miR-31 manipulation on radiosensitivity. Fluorometric ROS assays were performed to quantify ROS levels. The expression of potential miR-31 targets was measured by Western blot analysis. It was found that the manipulation of miR-31 altered the radiosensitivity in PDAC cells by regulating oxidative stress. Using online bioinformatics tools, we identified the 3'UTR of GPx8 as a predicted target of miR-31. Our study demonstrates, for the first time, that manipulating miR-31 alters GPx8 expression, regulating ROS detoxification and promoting either a radioresistant or radiosensitive phenotype. MiR-31 may represent a promising therapeutic target for altering radiosensitivity in PDAC cells.

Catalase Overexpression Drives an Aggressive Phenotype in Glioblastoma

Glioblastoma remains the deadliest form of brain cancer, largely because these tumors become resistant to standard of care treatment with radiation and chemotherapy. Intracellular production of reactive oxygen species (ROS) is necessary for chemo- and radiotherapy-induced cytotoxicity. Here, we assessed whether antioxidant catalase (CAT) affects glioma cell sensitivity to temozolomide and radiation. Using The Cancer Genome Atlas database, we found that CAT mRNA expression is upregulated in glioma tumor tissue compared with non-tumor tissue, and the level of expression negatively correlates with the overall survival of patients with high-grade glioma. In U251 glioma cells, CAT overexpression substantially decreased the basal level of hydrogen peroxide, enhanced anchorage-independent cell growth, and facilitated resistance to the chemotherapeutic drug temozolomide and ionizing radiation. Importantly, pharmacological inhibition of CAT activity reduced the proliferation of glioma cells isolated from patient biopsy samples. Moreover, U251 cells overexpressing CAT formed neurospheres in neurobasal medium, whereas control cells did not, suggesting that the radio- and chemoresistance conferred by CAT may be due in part to the enrichment of glioma stem cell populations. Finally, CAT overexpression significantly decreased survival in an orthotopic mouse model of glioma. These results demonstrate that CAT regulates chemo- and radioresistance in human glioma.

Catalase Overexpression Drives an Aggressive Phenotype in Glioblastoma

Glioblastoma remains the deadliest form of brain cancer, largely because these tumors become resistant to standard of care treatment with radiation and chemotherapy. Intracellular production of reactive oxygen species (ROS) is necessary for chemo- and radiotherapy-induced cytotoxicity. Here, we assessed whether antioxidant catalase (CAT) affects glioma cell sensitivity to temozolomide and radiation. Using The Cancer Genome Atlas database, we found that CAT mRNA expression is upregulated in glioma tumor tissue compared with non-tumor tissue, and the level of expression negatively correlates with the overall survival of patients with high-grade glioma. In U251 glioma cells, CAT overexpression substantially decreased the basal level of hydrogen peroxide, enhanced anchorage-independent cell growth, and facilitated resistance to the chemotherapeutic drug temozolomide and ionizing radiation. Importantly, pharmacological inhibition of CAT activity reduced the proliferation of glioma cells isolated from patient biopsy samples. Moreover, U251 cells overexpressing CAT formed neurospheres in neurobasal medium, whereas control cells did not, suggesting that the radio- and chemoresistance conferred by CAT may be due in part to the enrichment of glioma stem cell populations. Finally, CAT overexpression significantly decreased survival in an orthotopic mouse model of glioma. These results demonstrate that CAT regulates chemo- and radioresistance in human glioma.

Radioresistance in Prostate Cancer: Focus on the Interplay between NF-κB and SOD

Prostate cancer occurs frequently in men and can often lead to death. Many cancers, including prostate cancer, can be initiated by oxidative insult caused by free radicals and reactive oxygen species. The superoxide dismutase family removes the oxygen-derived reactive oxygen species, and increased superoxide dismutase activity can often be protective against prostate cancer. Prostate cancer can be treated in a variety of ways, including surgery, androgen deprivation therapy, radiation therapy, and chemotherapy. The clinical trajectory of prostate cancer varies from patient to patient, but more aggressive tumors often tend to be radioresistant. This is often due to the free-radical and reactive-oxygen-species-neutralizing effects of the superoxide dismutase family. Superoxide dismutase 2, which is especially important in this regard, can be induced by the NF-κB pathway, which is an important mechanism in radioresistance. This information has enabled the development of interventions that manipulate the NF-κB mechanism to treat prostate cancer.

Role of Glutathione Peroxidases and Peroxiredoxins in Free Radical-Induced Pathologies

In this review, we discuss the pathogenesis of some socially significant diseases associated with the development of oxidative stress, such as atherosclerosis, diabetes, and radiation sickness, as well as the possibilities of the therapeutic application of low-molecular-weight natural and synthetic antioxidants for the correction of free radical-induced pathologies. The main focus of this review is the role of two phylogenetically close families of hydroperoxide-reducing antioxidant enzymes peroxiredoxins and glutathione peroxidases - in counteracting oxidative stress. We also present examples of the application of exogenous recombinant antioxidant enzymes as therapeutic agents in the treatment of pathologies associated with free-radical processes and discuss the prospects of the therapeutic use of exogenous antioxidant enzymes, as well as the ways to improve their therapeutic properties.

The intricacies of NRF2 regulation in cancer

The complex role of NRF2 in the context of cancer continues to evolve. As a transcription factor, NRF2 regulates various genes involved in redox homeostasis, protein degradation, DNA repair, and xenobiotic metabolism. As such, NRF2 is critical in preserving cell function and viability, particularly during stress. Importantly, NRF2 itself is regulated via a variety of mechanisms, and the mode of NRF2 activation often dictates the duration of NRF2 signaling and its role in either preventing cancer initiation or promoting cancer progression. Herein, different modes of NRF2 regulation, including oxidative stress, autophagy dysfunction, protein-protein interactions, and epigenetics, as well as pharmacological modulators targeting this cascade in cancer, are explored. Specifically, how the timing and duration of these different mechanisms of NRF2 induction affect tumor initiation, progression, and metastasis are discussed. Additionally, progress in the discovery and development of NRF2 inhibitors for the treatment of NRF2-addicted cancers is highlighted, including modulators that inhibit specific NRF2 downstream targets. Overall, a better understanding of the intricate nature of NRF2 regulation in specific cancer contexts should facilitate the generation of novel therapeutics designed to not only prevent tumor initiation, but also halt progression and ultimately improve patient wellbeing and survival.

Gamma radiation negatively impacted seed germination, seedling growth and antioxidant enzymes activities in tall fescue infected with Epichloë endophyte

Plants and their accompanying microorganisms growing in contaminated sites with long-lived gamma-emitting radionuclides may be affected by radiation stress. The present study aimed to investigate the effects of gamma radiation on symbiotic relationship between Epichloë endophyte and Festuca arundinacea plant along with the radio-sensitivity of a pair of clones of tall fescue with (E+) and without (E-) symbiotic Epichloë endophyte exposed to different doses of gamma radiation including 25, 50, 75, 100, 150, 200, 300, and 400 Gray (Gy) from a Cobalt-60 source. Both irradiated and non-irradiated seeds of each status were grown under controlled conditions. Seed germination indices, seedling growth and certain physiological criteria associated with plant responses to oxidative stress were examined. The results revealed that low doses (up to 75 Gy) of gamma radiation stimulated seed germination indices and seedling growth. However, high doses (100-400 Gy) significantly reduced the final germination percentage, germination rate index, coefficient of velocity of germination, and the seed reserve depletion percentage, and enhanced the mean germination time. Further, high doses of radiation reduced root and shoot lengths, root and shoot fresh weights, and activities of antioxidant enzymes (especially catalase and superoxide dismutase), and increased the content of hydrogen peroxide (H2O2) and malondialdehyde (MDA) of the seedlings. The results showed that the endophyte was present in seeds after gamma ray irradiation. However, the presence of endophyte in seedlings started to be reduced significantly (18.45% reduction rather than the control) at 50 Gy of gamma radiation. High doses (100 Gy and above) dramatically declined the presence of endophyte down to zero in seedlings compared to the control. In this study, the E- clone had higher seed germination and seedling growth as well as lower H2O2 and MDA contents under radiation stress as compared with the E+ clone. Additionally, shoot tolerance index (STI) indicated more radiation tolerance in the E- clone. According to the results of the present study, it is concluded that biological impacts of gamma radiation stress and the harmful effects on endophyte viability may cause more radio-sensitivity and changes in the growth and physio-biochemical aspects of the host plant.

Acquired radioresistance in cancer associated fibroblasts is concomitant with enhanced antioxidant potential and DNA repair capacity

Background

Cancer-associated fibroblasts (CAFs) are a major component of the cancer stroma, and their response to therapeutic treatments likely impacts the outcome. We tested the hypothesis that CAFs develop unique characteristics that enhance their resistance to ionizing radiation.

Methods

CAFs were generated through intimate coculture of normal human fibroblasts of skin or lung origin with various human cancer cell types using permeable microporous membrane inserts. Fibroblasts and cancer cells are grown intimately, yet separately, on either side of the insert’s membrane for extended times to generate activated fibroblast populations highly enriched in CAFs.

Results

The generated CAFs exhibited a decrease in Caveolin-1 protein expression levels, a CAF biomarker, which was further enhanced when the coculture was maintained under in-vivo-like oxygen tension conditions. The level of p21^Waf1 was also attenuated, a characteristic also associated with accelerated tumor growth. Furthermore, the generated CAFs experienced perturbations in their redox environment as demonstrated by increases in protein carbonylation, mitochondrial superoxide anion levels, and modulation of the activity of the antioxidants, manganese superoxide dismutase and catalase. Propagation of the isolated CAFs for 25 population doublings was associated with enhanced genomic instability and a decrease in expression of the senescence markers β-galactosidase and p16^INK4a. With relevance to radiotherapeutic treatments, CAFs in coculture with cancer cells of diverse origins (breast, brain, lung, and prostate) were resistant to the clastogenic effects of ¹³⁷Cs γ rays compared to naïve fibroblasts. Addition of repair inhibitors of single- or double-stranded DNA breaks attenuated the resistance of CAFs to the clastogenic effects of γ rays, supporting a role for increased ability to repair DNA damage in CAF radioresistance.

Conclusions

This study reveals that CAFs are radioresistant and experience significant changes in indices of oxidative metabolism. The CAFs that survive radiation treatment likely modulate the fate of the associated cancer cells. Identifying them together with their mode of communication with cancer cells, and eradicating them, particularly when they may exist at the margin of the radiotherapy planning target volume, may improve the efficacy of cancer treatments.

Caveolin-1 promotes radioresistance in rhabdomyosarcoma through increased oxidative stress protection and DNA repair

The aim of this work was to investigate whether Caveolin-1 (Cav-1), a membrane scaffolding protein widely implicated in cancer, may play a role in radiation response in rhabdomyosarcoma (RMS), a pediatric soft tissue tumor. For this purpose, we employed human RD cells in which Cav-1 expression was stably increased via gene transfection. After radiation treatment, we observed that Cav-1 limited cell cycle arrest in the G2/M phase and enhanced resistance to cell senescence and apoptosis via reduction of p21^Cip1/Waf1, p16^INK4a and Caspase-3 cleavage. After radiotherapy, Cav-1-mediated cell radioresistance was characterized by low accumulation of H2AX foci, as confirmed by Comet assay, marked neutralization of reactive oxygen species (ROS) and enhanced DNA repair via activation of ATM, Ku70/80 complex and DNA-PK. We found that Cav-1-overexpressing RD cells, already under basal conditions, had higher glutathione (GSH) content and greater catalase expression, which conferred protection against acute treatment with hydrogen peroxide. Furthermore, pre-treatment of Cav-1-overexpressing cells with PP2 or LY294002 compounds restored the sensitivity to radiation treatment, indicating a role for Src-kinases and Akt pathways in Cav-1-mediated radioresistance. These findings were confirmed using radioresistant RD and RH30 lines generated by hypofractionated radiotherapy protocol, which showed marked increase of Cav-1, catalase and Akt, and sensitivity to PP2 and LY294002 treatment. In conclusion, these data suggest that concerted activity of Cav-1 and catalase, in cooperation with activation of Src-kinase and Akt pathways, may represent a network of vital mechanisms that allow irradiated RMS cells to evade cell death induced by oxidative stress and DNA damage.

Insight into the evolutionary profile of radio-resistance among insects having intrinsically evolved defence against radiation toxicity

Ionizing radiation (IR) has wide-ranging applications in various fields. In agriculture, pest control is one of the important applications, because insect pests have become a threat to the global agriculture industry. IR are used routinely to prevent crop loss and to protect stored food commodities. Radio-sterilization and disinfestation treatments are commonly used procedures for insect pest control. From various studies on insect radio-sterilization and disinfestation, it has been established that compared to vertebrates' insects have high levels of radiation resistance. Therefore, to achieve adequate radio-sterilization/disinfestation; exposure to high doses of IR is necessary. However, studies over decades made a presumption that radiation resistance is general among insects. Recent studies have shown that some insect orders are having high IR resistance and some insect orders are sensitive to IR. These studies have clarified that radiation resistance is not uniform throughout insect class. The present review is an attempt to insight at the evolutionary profile of insect species studied for radio-sterilization and disinfestation treatment and are having the trait of radio-resistance. From various studies on insect radiation resistance and after phylogenetic analysis of insect species it appears that the evolutionary near species have drastically different levels of radio-resistance and trait of radiation resistance appears to be independent of insect evolution.

Targeting cancer-cell mitochondria and metabolism to improve radiotherapy response

Radiotherapy is a regimen that uses ionising radiation (IR) to treat cancer. Despite the availability of several therapeutic options, cancer remains difficult to treat and only a minor percentage of patients receiving radiotherapy show a complete response to the treatment due to development of resistance to IR (radioresistance). Therefore, radioresistance is a major clinical problem and is defined as an adaptive response of the tumour to radiation-induced damage by altering several cellular processes which sustain tumour growth including DNA damage repair, cell cycle arrest, alterations of oncogenes and tumour suppressor genes, autophagy, tumour metabolism and altered reactive oxygen species. Cellular organelles, in particular mitochondria, are key players in mediating the radiation response in tumour, as they regulate many of the cellular processes involved in radioresistance. In this article has been reviewed the recent findings describing the cellular and molecular mechanism by which cancer rewires the function of the mitochondria and cellular metabolism to enhance radioresistance, and the role that drugs targeting cellular bioenergetics have in enhancing radiation response in cancer patients.

Cardenolides and pentacyclic triterpenes isolated from Acokanthera oblongifolia leaves: their biological activities with molecular docking study

Pentacyclic triterpenes and cardenolides were isolated from Acokanthera oblongifolia leaves. Their chemical structures were determined based on comprehensive 1D and 2D NMR spectroscopy. Their MIC was determined against 12 microorganisms. Their exerted cytotoxicity on the immortalized normal cells, hTERT-RPE1 was assessed by the sulforhodamine-B assay. The viral inhibitory effects of compounds against Newcastle disease virus (NDV) and H5N1 influenza virus IV were evaluated. Four in vitro antioxidant assays were performed in comparison with BHT and trolox and a weak activity was exhibited. Acovenoside A was with potent against H5N1-IV and NDV with IC₅₀ ≤ 3.2 and ≤ 2.1 μg/ml and SI values of 93.75 and 95.23%, respectively, in comparison to ribavirin. Its CC₅₀ record on Vero cells was > 400 and 200 μg/ml, respectively. Acobioside A was the most active compound against a broad range of microbes while Pseudomonas aeruginosa was the most sensitive. Its MIC (0.07 μg/ml) was 1/100-fold of the recorded CC₅₀ (7.1 μg/ml/72 h) against hTERT-RPE1. The molecular docking of compounds on human DNA topoisomerase I (Top1-DNA) and IV glycoprotein hemagglutinin were studied using MOE program. This study has introduced the cardenolides rather than triterpenoids with the best docking score and binding interaction with the active site of the studied proteins.

Determining the Cytotoxicity of Oxidized Lipids in Cultured Caco-2 Cells Using Bioimaging Techniques

Fish lipids are comprised of considerable quantities of polyunsaturated acids and are prone to oxidation, producing reactive oxygen species and hydroperoxides. This study aimed to evaluate the biochemical and structural alterations in Caco-2 cells following exposure to 100 μg/mL methyl linoleate or fish oil, and then radiated for 24, 48 or 72 h. Electron spin resonance spectroscopy detected free radicals in the lipid membrane, Raman microscopy observed biochemical alterations and atomic force microscopy identified changes in morphology, such as the breakdown of DNA bonds. The study showed that bioimaging and biochemical techniques can be effective at detecting and diagnosing cellular injuries incurred by lipid peroxidation.

Heterogeneity of chondrosarcomas response to irradiations with X-rays and carbon ions: A comparative study on five cell lines

Objectives

Chondrosarcomas are malignant bone tumors considered as resistant to radiotherapy. To unravel mechanisms of resistance, we compared biological responses of several chondrosarcomas to X-ray irradiations in normoxia and hypoxia. Since hadrontherapy with Carbon-ions gave interesting clinical outcomes, we also investigated this treatment in vitro.

Methods

Five human chondrosarcoma cell lines were used and cultured in normoxia or hypoxia. Their sensitivities to irradiations were determined by carrying out survival curves. DNA damage was monitored by γH2AX expression. Apoptosis was assessed by cell cycle analysis and Apo2.7 expression, and by evaluating PARP cleavage. Senescence was evaluated using SA β-galactosidase assay. Necrosis, and autophagy, were evaluated by RIP1 and beclin-1 expression, respectively. Mutations in relevant biological pathways were screened by whole-exome sequencing.

Results

X-ray radiations induced death in some chondrosarcomas by both apoptosis and senescence (CH2879), or by either of them (SW1353 and JJ012), whereas no death was observed in other cell lines (FS090 and 105KC). Molecularly, p21 was overexpressed when senescence was elicited. Genetic analysis allowed to identify putative genes (such as TBX3, CDK2A, HMGA2) permitting to predict cell response to irradiations. Unexpectedly, chronic hypoxia did not favor radioresistance in chondrosarcomas, and even increased the radiosensitivity of JJ012 line. Finally, we show that carbon ions triggered more DNA damages and death than X-rays.

Conclusions

Chondrosarcomas have different response to irradiation, possibly due to their strong genetic heterogeneity. p21 expression is suggested as predictive of X-ray-induced senescence. Surprisingly, hypoxia does not increase the radioresistance of chondrosarcomas, but as expected Carbon ion beams are more effective that X-rays in normoxia, whereas their efficiency was also variable depending on cell lines.

Tolerance of Novel Toxins through Generalized Mechanisms: Simulating Gradual Host Shifts of Butterflies

Organisms encounter a wide range of toxic compounds in their environments, from chemicals that serve anticonsumption or anticompetition functions to pollutants and pesticides. Although we understand many detoxification mechanisms that allow organisms to consume toxins typical of their diet, we know little about why organisms vary in their ability to tolerate entirely novel toxins. We tested whether variation in generalized stress responses, such as antioxidant pathways, may underlie variation in reactions to novel toxins and, if so, their associated costs. We used an artificial diet to present cabbage white butterfly caterpillars (Pieris rapae) with plant material containing toxins not experienced in their evolutionary history. Families that maintained high performance (e.g., high survival, fast development time, large body size) on diets containing one novel toxic plant also performed well when exposed to two other novel toxic plants, consistent with a generalized response. Variation in constitutive (but not induced) expression of genes involved in oxidative stress responses was positively related to performance on the novel diets. While we did not detect reproductive trade-offs of this generalized response, there was a tendency to have less melanin investment in the wings, consistent with the role of melanin in oxidative stress responses. Taken together, our results support the hypothesis that variation in generalized stress responses, such as genes involved in oxidative stress responses, may explain the variation in tolerance to entirely novel toxins and may facilitate colonization of novel hosts and environments.

Molecular cloning and functional characterization of a Cu/Zn superoxide dismutase from jellyfish Cyanea capillata

We identified and characterized a novel superoxide dismutase (SOD), designated as CcSOD1, from the cDNA library from the tentacle tissue of the jellyfish Cyanea capillata. The full-length cDNA sequence of CcSOD1 consists of 745 nucleotides with an open reading frame encoding a mature protein of 154 amino acids, sharing a predicted structure similar to the typical Cu/Zn-SODs. The CcSOD1 coding sequence was cloned into the expression vector pET-24a and successfully expressed in Escherichia coli Rosetta (DE3) pLysS. The recombinant protein rCcSOD1 was purified by HisTrap High Performance chelating column chromatography and analyzed for its biological function. Our results showed that the purified rCcSOD1 could inhibit superoxide anion and keep active in a pH interval of 4.5-9 and a temperature interval of 10-70°C. Even when heated at 70°C for 60 min, rCcSOD1 retained 100% activity, indicating a relatively high thermostability. These results suggest that CcSOD1 protein may play an important role in protecting jellyfish from oxidative damage and can serve as a new resource for antioxidant products.

Physiological consequences of gamma ray irradiation in tall fescue with elimination potential of Epichloë fungal endophyte

Perennial plants and their associated microorganisms grow in the areas that may be contaminated with long-lived gamma-emitting radionuclides. This will induce gamma stress response in plants and their accompanying microorganisms. The present work investigated the growth and physiological responses of Epichloe endophyte infected tall fescue to gamma radiation, as well as whether the endophyte could persist and infect the host plant once exposed to gamma radiation. Seeds of Iranian native genotype of 75B⁺ of tall fescue were exposed to different doses, including 5.0, 10.0, 15.0, 20.0, 30.0 and 40.0 krad of gamma ray from a ⁶⁰Co source. Irradiated and unirradiated seeds were sown in pots and grown under controlled conditions in the greenhouse. The growth and physiological parameters associated with plant tolerance to oxidative stress of host plants, as well as endophytic infection frequency (% of plants infected) and intensity (mean number of endophytic hyphae per the field of view), were examined in 3 months-old seedlings. The results indicated that all gamma radiation doses (except 5.0 kr) significantly reduced the height and survival percentage of the host plant. Days to the emergence of seedling increased gradually as gamma doses rose. A dose-rate dependent induction was seen for photosynthetic pigments and proline content. Malondialdehyde (MDA) content grew with elevation of irradiation doses. Depending on the dose and time, the activities of antioxidant enzymes in the host plant responded differently to gamma radiation. Gamma radiation altered the enzyme activities with sever decline in SOD and CAT activities. However, it had barely any effect on in APX and POD activities. The results also revealed that the persistence and intensity of endophyte were affected after gamma-ray irradiation. The initial percentage of tall fescue seeds infected with the endophyte was 91% in un-irradiated seeds. Presence of the viable endophyte started to decline significantly (23%) at 5.0 kr of gamma radiation. A dramatic reduction in the presence and intensity of endophyte occurred at 10.0 to 40.0 kr intensities. Gamma radiation × trait (GT)-biplot analysis indicated positive correlations between the endophyte symbiosis and antioxidant enzyme activities. Also, negative correlations were observed between the endophyte and MDA content in the host plant. Our results suggest that radiation stress (doses over 5.0 kr) caused reduction in the growth and antioxidant enzyme activities of the host plant that accompanied by a dramatic reduction in the persistence and intensity of endophyte fungi. Our findings have provided the basic information for future studies on the effect of gamma irradiation on the interaction between endophytic fungi and its host plant.

Hepatotoxicity and renal toxicity induced by gamma-radiation and the modulatory protective effect of Ficus carica in male albino rats

It is well-known that gamma radiation initiates generation of free radicals which prompting serious cellular damages in biological systems. In the present study, we investigated the role of Ficus carica, a natural antioxidant substance, in modulating changes in liver and kidney functions, antioxidant enzyme's gene expression, and apoptosis, in male albino rats exposed to gamma radiation. A total of 40 rats were used in this experiment and divided equally into 4 groups: Group 1, rats administered distilled H₂O (Control); Group 2, rats administered F. carica; Group 3, rats irradiated; and Group 4, rats treated with F. carica and irradiated. Groups 3 and 4 were exposed to whole-body gamma radiations at a dose level of 8 Gy and with a dose rate of 0.762 Gy/min. F. carica was administered to rats by gavage, for 3 consecutive weeks, before exposure to radiation. Five rats were sacrificed from each group at intervals of 24 and 72 h after cessation of treatment. The results revealed marked increases in alanine aminotransferase and aspartate aminotransferase levels in liver, a decrease in albumin level and increase in urea level in kidney. Irradiation resulted in cytotoxic effects as indicated by elevation in antioxidant enzyme's gene expression at 24 h, the opposite was observed at 72 h. Immunohistochemical analysis revealed that cytochrome c and p53 expressions significantly increased following exposure to radiation. Oral administration of F. carica pre-irradiation as a natural product plays a modulatory protective and anti-apoptotic role against cells damaged by free radicals induced by whole-body irradiation.

Peroxiredoxins in Colorectal Cancer: Predictive Biomarkers of Radiation Response and Therapeutic Targets to Increase Radiation Sensitivity?

Colorectal cancer (CRC) is the third most common cancer in the Western world, with one-third of cases located in the rectum. Preoperative radiotherapy is the standard of care for many patients with rectal cancer but has a highly variable response rate. The ability to predict response would be of great clinical utility. The response of cells to ionizing radiation is known to involve immediate damage to biomolecules and more sustained disruption of redox homeostasis leading to cell death. The peroxiredoxins are an important group of thiol-dependent antioxidants involved in protecting cells from oxidative stress and regulating signaling pathways involved in cellular responses to oxidative stress. All six human peroxiredoxins have shown increased expression in CRC and may be associated with clinicopathological features and tumor response to ionizing radiation. Peroxiredoxins can act as markers of oxidative stress in various biological systems but they have not been investigated in this capacity in CRC. As such, there is currently insufficient evidence to support the role of peroxiredoxins as clinical biomarkers, but it is an area worthy of investigation. Future research should focus on the in vivo response of rectal cancer to radiotherapy and the redox status of peroxiredoxins in rectal cancer cells, in order to predict response to radiotherapy. The peroxiredoxin system is also a potential therapeutic target for CRC.

HZ08 suppresses RelB-activated MnSOD expression and enhances Radiosensitivity of prostate Cancer cells

Background

The development of radioresistance is one of main causes for therapeutic failure of prostate cancer (PCa). The present study aims to investigate the function and the related mechanism by which HZ08 sensitizes radiotherapeutic efficiency to treat aggressive PCa cells.

Methods

PCa cells were pretreated with HZ08 (6,7-dimethoxy-1-(3,4-dimethoxy) benzyl-2-(N-n-octyl-N′-cyano) guanyl-1,2,3,4-tetrahydroisoquinoline) and followed by ionizing radiation (IR) treatment. Cytotoxicity in the treated cells was analyzed to assess the radiosensitization capacity of HZ08 by flow cytometry, MTT and colony survival assays. The cellular levels of reactive oxygen species (ROS) and oxygen consumption rates (OCR) were measured using specific ROS detection probes and a Seahorse XF96 Analyzer, respectively. RelB binding to the NF-κB intronic enhancer region of the human SOD2 gene was determined using a ChIP assay. The levels of phosphorylation of PI3K, Akt and IKKα were quantified and further confirmed using a PI3K inhibitor. Finally, the synergistic effect of HZ08 on radiosensitization of PCa cells was validated using a mouse xenograft tumor model.

Results

HZ08 enhanced radiosensitivity of PCa cells through increasing ROS and declining mitochondrial respiration due to suppression of mitochondrial antioxidant enzyme MnSOD. Mechanistically, HZ08 appeared to inhibit PI3K/Akt/IKKα signaling axis, resulting in transcriptional repression of MnSOD expression by preventing RelB nuclear translocation.

Conclusions

HZ08 can serve as a useful radiosensitizing agent to improve radiotherapy for treating aggressive PCa cells with high level of constitutive RelB. The present study suggests a promising approach for enhancing radiotherapeutic efficiency to treat advanced PCa by inhibiting antioxidant defense function.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0849-5) contains supplementary material, which is available to authorized users.

Role of the oxidative stress index, myeloperoxidase, catalase activity for cardiac allograft vasculopathy in heart transplant recipients

BACKGROUND

The aim of this study was to explore the role of oxidative stress index (OSI), myeloperoxidase (MPO), and catalase (CAT) activity in cardiac allograft vasculopathy (CAV) in heart transplant recipients (HTRs).

METHODS

The study enrolled a median age of 41 ± 9 years 47 recipients. The HTx patients were divided into two groups based on the presence CAV as follows: CAV⁽⁺⁾ and CAV^(-) group. Also, CAV⁽⁺⁾ group were divided into two groups as mild/moderate to severe CAV. The OSI, MPO, and CAT activity were analyzed in both groups.

RESULTS

The mean total antioxidant capacity (0.79 ± 0.46 vs 1.03 ± 0.33 μmol H₂ O₂ equiv/L) P = .043 was significantly lower and OSI, MPO, CAT activity were significantly higher in CAV⁽⁺⁾ group (63 ± 38 vs 20 ± 16 arbitrary unit, P = .001; 398 ± 242 vs 139  ± 112 μg/L, P = .001; 51 ± 42 vs 26 ± 23 pmol/mg protein, P = .013, respectively). Also, mean OSI (38 ± 41 vs 93 ± 75, P = .05) were significantly higher in severe CAV⁽⁺⁾ group. Recipient age, male gender, and low density lipoprotein-cholesterol were significantly higher in CAV⁽⁺⁾ group. There was a moderate correlation between the CAV grade and OSI, MPO, and CAT levels in univariate analysis (r = .560, P = .002; r = .643, P = .007; r = .681, P = .001, respectively).

CONCLUSION

An increase in the serum level of OSI, MPO, and CAT was associated with CAV in HTRs.

Preincubation with glutathione ethyl ester improves the developmental competence of vitrified mouse oocytes

PURPOSE

Oocyte vitrification is currently used for human fertility preservation. However, vitrification damage is a problem caused by decreasing ooplasmic levels of glutathione (GSH). The GSH donor glutathione ethyl ester (GSH-OEt) can significantly increase the GSH content in oocytes. However, it is difficult to obtain oocyte from woman. To overcome this, we used mouse oocytes to replace human oocytes as a model of study.

METHODS

Oocytes from B6D2F1 mice were preincubated for 30 min with 2.5 mmol/L GSH-OEt (GSH-OEt group), without GSH-OEt preincubation before vitrification (control vitrification group) or in nonvitrified oocytes (fresh group). After thawing, oocytes were fertilized for evaluating the developmental competence of embryos in vitro and in vivo. Immunofluorescence, Polscope equipment and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were used to analyze damage, including mitochondrial distribution, reactive oxygen species (ROS) levels, spindle morphology, and gene expression levels (Bcl-2, BAX, and MnSOD).

RESULTS

The rates of fertilization, 3-4 cell, blastocyst formation and expanded blastocysts were significantly higher (p < 0.05) in the GSH-OEt group (90.4%; 91.1%; 88.9% and 63.0%) than in the control (80.0%; 81.4%; 77.7% and 50.5%). Provided embryos overcame the 2-cell block and developed to the blastocyst stage, birth rates of all groups were similar. Vitrification altered mitochondrial distribution, increased ROS levels, and caused abnormal spindle morphology; GSH-OEt preincubation could improve such damage. RT-qPCR showed that the expression of Bcl-2 was lower in the control group compared with the GSH-OEt group; BAX and MnSoD expression levels were higher in the control group than in the GSH-OEt group (p < 0.05).

CONCLUSIONS

The beneficial effect of GSH-OEt preincubation occurred before the 2-cell stage.

Distributions of manganese in diverse human cancers provide insights into tumour radioresistance

We show that measuring manganese levels in tumours of cancer patients is predictive for their radiation treatment.

Mitigation of whole-body gamma radiation-induced damages by Clerodendron infortunatum in mammalian organisms

Several phytoceuticals and extracts of medicinal plants are reported to mitigate deleterious effects of ionizing radiation. The potential of hydro-alcoholic extract of Clerodendron infortunatum (CIE) for providing protection to mice exposed to gamma radiation was investigated. Oral administration of CIE bestowed a survival advantage to mice exposed to lethal doses of gamma radiation. Radiation-induced depletion of the total blood count and bone marrow cellularity were prevented by treatment with CIE. Damage to the cellular DNA (as was evident from the comet assay and the micronucleus index) was also found to be decreased upon CIE administration. Radiation-induced damages to intestinal crypt cells was also reduced by CIE. Studies on gene expression in intestinal cells revealed that there was a marked increase in the Bax/Bcl-2 ratio in mice exposed to whole-body 4 Gy gamma radiation, and that administration of CIE resulted in significant lowering of this ratio, suggestive of reduction of radiation-induced apoptosis. Also, in the intestinal tissue of irradiated animals, following CIE treatment, levels of expression of the DNA repair gene Atm were found to be elevated, and there was reduction in the expression of the inflammatory Cox-2 gene. Thus, our results suggest a beneficial use of Clerodendron infortunatum for mitigating radiation toxicity.

Oxidative Stress in Tunisian Patients With Acute Lymphoblastic Leukemia and Its Involvement in Leukemic Relapse

The aim of the present study was to evaluate in patients with acute lymphoblastic leukemia (ALL), the oxidative status and antioxidant defense and its involvement in the relapse of ALL. The plasmatic levels of malondialdehyde, advanced oxidation of protein products and reduced glutathione (GSH), and the plasmatic activities of catalase, superoxide dismutase (SOD), and glutathione peroxidase were determined in 34 patients who were newly diagnosed with ALL and compared with 92 healthy individuals. The plasmatic concentrations of malondialdehyde and advanced oxidation of protein products were higher in ALL patients than in controls and increased during chemotherapy. A decrease in glutathione peroxidase activity and an increase in catalase and SOD activities and GSH plasma levels were observed in ALL patients, as compared with sex-matched controls. Moreover, SOD activity and GSH levels were significantly correlated with the relapse of ALL patients. These data suggest the involvement of oxidative stress in acute lymphoid leukemias and leukemic relapse.

Whole body radioprotective effect of phenolic extracts from the fruits of Malus baccata (Linn.) Borkh

This study was designed to evaluate the radioprotective effect of phenolics extracted from the fruits of Malus baccata (Linn.) Borkh. (MBP-3b) against damage induced by (60)Co γ-irradiation in vivo. MBP-3b could significantly improve the activity of endogenous antioxidant enzymes and the T-AOC, as well as reduce the MDA level in the liver and kidneys of irradiated mice. In addition, pretreatment with MBP-3b at a dose of 150 mg per kg bw could significantly enhance immunomodulation activity by promoting the proliferation of spenocytes and monocyte phagocytosis. The administration of MBP-3b prevented the decline induced by radiation of haematological parameters (WBC, RBC, PLT and HGB). Furthermore, MBP-3b could protect spenocytes from radiation-induced damage by inhibiting cell apoptosis. The results indicated that MBP-3b possesses strong whole body radioprotective and immunomodulatory activities. The main constituents of MBP-3b were tentatively identified as delphinidin-3,5-diglucoside, cyanidin-3-glucoside, chlorogenic acid, proanthocyanidin C1, quercetin-3-galactoside, quercetin-3-glucoside, quercetin-3-xyloside/arabinoside, phloretin-2-xyloseglucoside, quercetin-3-rhamnoside and phlorizin. MBP-3b could be used as a probable radioprotector against gamma radiation induced oxidative damage.

Modulatory effects of new curcumin analogues on gamma-irradiation - Induced nephrotoxicity in rats

In the present study, a new series of 2-amino-pyran-3-carbonitrile derivatives of curcumin 2-7 have been synthesized via one-pot simple and efficient protocol, involving the reaction of curcumin 1 with substituted-benzylidene-malononitrile to modify the 1,3-diketone moiety. The structures of the synthesized compounds 2-7 were elucidated by microanalytical and spectral data, which were found consistent with the assigned structures. The nephroprotective mechanism of these new curcumin analogues was evaluated on the post-gamma-irradiation (7 Gy) - induced nephrotoxicity in rats. Activation of Nrf2 by these curcumin analogues is responsible for the amendment of the antioxidant status, impairment of NF-κB signal, thus attenuate the nephrotoxicity induced post-γ-irradiation exposure. 4-Chloro-phenyl curcumin analogue 7 showed the most potent activity. In conclusion, the results of the present study demonstrate a promising role of these new curcumin analogues to attenuate the early symptoms of nephrotoxicity induced by γ-irradiation in rats via activation of Nrf2 gene expression. These new curcumin analogues need further toxicological investigations to assess their therapeutic index.

Loss of C/EBPδ enhances IR-induced cell death by promoting oxidative stress and mitochondrial dysfunction

Exposure of cells to ionizing radiation (IR) generates reactive oxygen species (ROS). This results in increased oxidative stress and DNA double strand breaks (DSBs) which are the two underlying mechanisms by which IR causes cell/tissue injury. Cells that are deficient or impaired in the cellular antioxidant response are susceptible to IR-induced apoptosis. The transcription factor CCAAT enhancer binding protein delta (Cebpd, C/EBPδ) has been implicated in the regulation of oxidative stress, DNA damage response, genomic stability and inflammation. We previously reported that Cebpd-deficient mice are sensitive to IR and display intestinal and hematopoietic injury, however the underlying mechanism is not known. In this study, we investigated whether an impaired ability to detoxify IR-induced ROS was the underlying cause of the increased radiosensitivity of Cebpd-deficient cells. We found that Cebpd-knockout (KO) mouse embryonic fibroblasts (MEFs) expressed elevated levels of ROS, both at basal levels and after exposure to gamma radiation which correlated with increased apoptosis, and decreased clonogenic survival. Pre-treatment of wild type (WT) and KO MEFs with polyethylene glycol-conjugated Cu-Zn superoxide dismutase (PEG-SOD) and catalase (PEG-CAT) combination prior to irradiation showed a partial rescue of clonogenic survival, thus demonstrating a role for increased intracellular oxidants in promoting IR-induced cell death. Analysis of mitochondrial bioenergetics revealed that irradiated KO MEFs showed significant reductions in basal, adenosine triphosphate (ATP)-linked, maximal respiration and reserved respiratory capacity and decrease in intracellular ATP levels compared to WT MEFs indicating they display mitochondrial dysfunction. KO MEFs expressed significantly lower levels of the cellular antioxidant glutathione (GSH) and its precursor- cysteine as well as methionine. In addition to its antioxidant function, GSH plays an important role in detoxification of lipid peroxidation products such as 4-hydroxynonenal (4-HNE). The reduced GSH levels observed in KO MEFs correlated with elevated levels of 4-HNE protein adducts in irradiated KO MEFs compared to respective WT MEFs. We further showed that pre-treatment with the GSH precursor, N-acetyl L-cysteine (NAC) prior to irradiation showed a significant reduction of IR-induced cell death and increases in GSH levels, which contributed to the overall increase in clonogenic survival of KO MEFs. In contrast, pre-treatment with the GSH synthesis inhibitor- buthionine sulfoximine (BSO) further reduced the clonogenic survival of irradiated KO MEFs. This study demonstrates a novel role for C/EBPδ in protection from basal as well as IR-induced oxidative stress and mitochondrial dysfunction thus promoting post-radiation survival.

Pomegranate Intake Protects Against Genomic Instability Induced by Medical X-rays In Vivo in Mice

Ionizing radiation (IR) is a well-documented human carcinogen. The increased use of IR in medical procedures has doubled the annual radiation dose and may increase cancer risk. Genomic instability is an intermediate lesion in IR-induced cancer. We examined whether pomegranate extract (PE) suppresses genomic instability induced by x-rays. Mice were treated orally with PE and exposed to an x-ray dose of 2 Gy. PE intake suppressed x-ray-induced DNA double-strand breaks (DSBs) in peripheral blood and chromosomal damage in bone marrow. We hypothesized that PE-mediated protection against x-ray-induced damage may be due to the upregulation of DSB repair and antioxidant enzymes and/or increase in glutathione (GSH) levels. We found that expression of DSB repair genes was not altered (Nbs1 and Rad50) or was reduced (Mre11, DNA-PKcs, Ku80, Rad51, Rad52 and Brca2) in the liver of PE-treated mice. Likewise, mRNA levels of antioxidant enzymes were reduced (Gpx1, Cat, and Sod2) or were not altered (HO-1 and Sod1) as a function of PE treatment. In contrast, PE-treated mice with and without IR exposure displayed higher hepatic GSH concentrations than controls. Thus, ingestion of pomegranate polyphenols is associated with inhibition of x-ray-induced genomic instability and elevated GSH, which may reduce cancer risk.

Radioprotective effects of hesperidin on oxidative damages and histopathological changes induced by X-irradiation in rats heart tissue

This study was carried out to evaluate radioprotective effects of hesperidin (HES) administration before the irradiation on the cardiac oxidative stress and histopathological changes in an experimental rat model. The cardiovascular complications of radiation exposure cause morbidity and mortality in patients who received radiotherapy. HES, an antioxidant flavonoid found in citrus fruits, suggests the protection against the tissue damage. Fifty-eight rats were divided into four groups: Group 1 received phosphate buffered saline (PBS) and sham radiation; Group 2, HES and sham radiation; Group 3, PBS and radiation; and Group 4, HES and radiation. The rats were exposed to single dose of 18 Gy of 6 MV X-ray. One hundred milligrams per kilogram doses of HES was administered for 7 days before irradiation. The estimation of superoxide dismutase (SOD), malondialdehyde (MDA), and histopathological analyses was performed at 24 h and 8 weeks after radiation exposure. The irradiation of chest area resulted in an elevated MDA level and decreased SOD activity. Moreover, long-term pathological lesions of radiation were inflammation, fibrosis, the increased number of mast cells and macrophages, and development of plaque, vascular leakage, myocardial degeneration, and myocyte necrosis. Although the administration of HES decreases inflammation, fibrosis, mast cell and macrophage numbers, and myocyte necrosis, it did not result in reduced thrombus, myocardium degeneration, and vascular leakage. In conclusion, these results suggest that HES can perform a radioprotection action. The protective effect of HES may be attributable to its immunomodulatory effects and free radical-scavenging properties.

56Fe irradiation-induced cognitive deficits through oxidative stress in mice

The rapid growth of manned space flight results in more concerns about health risks and an urgent need for health assessment for space travel. The cosmic environment is complicated and full of radiation. Because of their strong biological effects, heavy ions such as ⁵⁶Fe ions are considered to be an important component of these lethal galactic rays. Due to the importance of brain function to astronauts, we explored the long-term effects and potential mechanisms of ⁵⁶Fe ion radiation on mice brains containing the hippocampus. In our study, radiation doses were carried out with 0.5 Gy, 1 Gy or 2 Gy. One month after whole-body ⁵⁶Fe ion exposure, the Morris water maze test was performed to assess the ability of spatial learning and memory. A histological study was used for pathology analysis of the hippocampus. Alteration of oxidative stress was reflected by MDA and GSH and oxidative DNA damage marked by 8-OHdG was detected by biochemical and immunofluorescence methods. In our results, irradiated groups exhibited significant changes in behavioral performance and also showed loose and edematous arrangement in the pathological characteristics. Furthermore, whole brain levels of MDA, GSH and 8-OHdG increased in the irradiated groups. In addition, increased expression of 8-OHdG can also be detected by immunofluorescence in the hippocampus. Our findings revealed a linkage between radiation-induced oxidative stress and behavioral deficits. This may suggest an underlying mechanism of brain tissue protection and risk assessment in manned space flight.

Factors Affecting the Radiosensitivity of Hexaploid Wheat to γ-Irradiation: Radiosensitivity of Hexaploid Wheat (Triticum aestivum L.) [Corrected]

Understanding the radiosensitivity of plants, an important factor in crop mutation breeding programs, requires a thorough investigation of the factors that contribute to this trait. In this study, we used the highly radiosensitive wheat (Triticum aestivum L.) variety HY1 and J411, a γ-irradiation-insensitive control, which were screened from a natural population, to examine the factors affecting radiosensitivity, including free radical content and total antioxidant capacity, as well as the expression of TaKu70 and TaKu80 (DNA repair-related genes) as measured by real-time PCR. We also investigated the alternative splicing of this gene in the wild-type wheat ecotype by sequence analysis. Free radical contents and total antioxidant capacity significantly increased upon exposure of HY1 wheat to γ-irradiation in a dose-dependent manner. By contrast, in J411, the free radical contents exhibited a similar trend, but the total antioxidant capacity exhibited a downward trend upon increasing γ-irradiation. Additionally, we detected dose-dependent increases in TaKu70 and TaKu80 expression levels in γ-irradiated HY1, while in J411, TaKu70 expression levels increased, followed by a decline. We also detected alternative splicing of TaKu70 mRNA, namely, intron retention, in HY1 but not in J411. Our findings indicate that γ-irradiation induces oxidative stress and DNA damage in hexaploid wheat, resulting in growth retardation of seedlings, and they suggest that TaKu70 may play a causal role in radiosensitivity in HY1. Further studies are required to exploit these factors to improve radiosensitivity in other wheat varieties.