Rapid proteomic remodeling of cardiac tissue caused by total body ionizing radiation

Role of ferroptosis in radiation-induced soft tissue injury

Ionizing radiation has been pivotal in cancer therapy since its discovery. Despite its therapeutic benefits, IR causes significant acute and chronic complications due to DNA damage and the generation of reactive oxygen species, which harm nucleic acids, lipids, and proteins. While cancer cells are more vulnerable to ionizing radiation due to their inefficiency in repairing damage, healthy cells in the irradiated area also suffer. Various types of cell death occur, including apoptosis, necrosis, pyroptosis, autophagy-dependent cell death, immunogenic cell death, and ferroptosis. Ferroptosis, driven by iron-dependent lipid peroxide accumulation, has been recognized as crucial in radiation therapy's therapeutic effects and complications, with extensive research across various tissues. This review aims to summarize the pathways involved in radiation-related ferroptosis, findings in different organs, and drugs targeting ferroptosis to mitigate its harmful effects.

Dexmedetomidine ameliorates x-ray-induced myocardial injury via alleviating cardiomyocyte apoptosis and autophagy

BACKGROUND

Radiotherapy is a primary local treatment for tumors, yet it may lead to complications such as radiation-induced heart disease (RIHD). Currently, there is no standardized approach for preventing RIHD. Dexmedetomidine (Dex) is reported to have cardio-protection effects, while its role in radiation-induced myocardial injury is unknown. In the current study, we aimed to evaluate the radioprotective effect of dexmedetomidine in X-ray radiation-treated mice.

METHODS

18 male mice were randomized into 3 groups: control, 16 Gy, and 16 Gy + Dex. The 16 Gy group received a single dose of 16 Gy X-ray radiation. The 16 Gy + Dex group was pretreated with dexmedetomidine (30 µg/kg, intraperitoneal injection) 30 min before X-ray radiation. The control group was treated with saline and did not receive X-ray radiation. Myocardial tissues were collected 16 weeks after X-ray radiation. Hematoxylin-eosin staining was performed for histopathological examination. Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining was performed to assess the state of apoptotic cells. Immunohistochemistry staining was performed to examine the expression of CD34 molecule and von Willebrand factor. Besides, western blot assay was employed for the detection of apoptosis-related proteins (BCL2 apoptosis regulator and BCL2-associated X) as well as autophagy-related proteins (microtubule-associated protein 1 light chain 3, beclin 1, and sequestosome 1).

RESULTS

The findings demonstrated that 16 Gy X-ray radiation resulted in significant changes in myocardial tissues, increased myocardial apoptosis, and activated autophagy. Pretreatment with dexmedetomidine significantly protects mice against 16 Gy X-ray radiation-induced myocardial injury by inhibiting apoptosis and autophagy.

CONCLUSION

In summary, our study confirmed the radioprotective effect of dexmedetomidine in mitigating cardiomyocyte apoptosis and autophagy induced by 16 Gy X-ray radiation.

A new approach of nano-metformin as a protector against radiation-induced cardiac fibrosis and inflammation via CXCL1/TGF-Β pathway

The present work investigates the potential role of metformin nanoparticles (MTF-NPs) as a radio-protector against cardiac fibrosis and inflammation induced by gamma radiation via CXCL1/TGF-β pathway. Lethal dose fifty of nano-metformin was determined in mice, then 21 rats (male albino) were equally divided into three groups: normal control (G1), irradiated control (G2), and MTF-NPs + IRR (G3). The possible protective effect of MTF-NPs is illustrated via decreasing cardiac contents of troponin, C-X-C motif Ligand 1 (CXCL1), tumor growth factor β (TGF-β), protein kinase B (AKT), and nuclear factor-κB (NF-κB). Also, the positive effect of MTF-NPs on insulin-like growth factor (IGF) and platelet-derived growth factor (PDGF) in heart tissues using immunohistochemical technique is illustrated in the present study. Histopathological examination emphasizes the biochemical findings. The current investigation suggests that MTF-NPs might be considered as a potent novel treatment for the management of cardiac fibrosis and inflammation in patients who receive radiotherapy or workers who may be exposed to gamma radiation.

Radiation-induced changes in energy metabolism result in mitochondrial dysfunction in salivary glands

Salivary glands are indirectly damaged during radiotherapy for head and neck cancer, resulting in acute and chronic hyposalivation. Current treatments for radiation-induced hyposalivation do not permanently restore function to the gland; therefore, more mechanistic understanding of the damage response is needed to identify therapeutic targets for lasting restoration. Energy metabolism reprogramming has been observed in cancer and wound healing models to provide necessary fuel for cell proliferation; however, there is limited understanding of alterations in energy metabolism reprogramming in tissues that fail to heal. We measured extracellular acidification and oxygen consumption rates, assessed mitochondrial DNA copy number, and tested fuel dependency of irradiated primary salivary acinar cells. Radiation treatment leads to increases in glycolytic flux, oxidative phosphorylation, and ATP production rate at acute and intermediate time points. In contrast, at chronic radiation time points there is a significant decrease in glycolytic flux, oxidative phosphorylation, and ATP production rate. Irradiated salivary glands exhibit significant decreases in spare respiratory capacity and increases in mitochondrial DNA copy number at days 5 and 30 post-treatment, suggesting a mitochondrial dysfunction phenotype. These results elucidate kinetic changes in energy metabolism reprogramming of irradiated salivary glands that may underscore the chronic loss of function phenotype.

Radiation-Induced Changes in Energy Metabolism Result in Mitochondrial Dysfunction in Salivary Glands

Salivary glands are indirectly damaged during radiotherapy for head and neck cancer, resulting in acute and chronic hyposalivation. Current treatments for radiation-induced hyposalivation do not permanently restore function to the gland; therefore, more mechanistic understanding of the damage response is needed to identify therapeutic targets for lasting restoration. Energy metabolism reprogramming has been observed in cancer and wound healing models to provide necessary fuel for cell proliferation; however, there is limited understanding of alterations in energy metabolism reprogramming in tissues that fail to heal. We measured extracellular acidification and oxygen consumption rates, assessed mitochondrial DNA copy number, and tested fuel dependency of irradiated primary salivary acinar cells. Radiation treatment leads to increases in glycolytic flux, oxidative phosphorylation, and ATP production rate at acute and intermediate time points. In contrast, at chronic radiation time points there is a significant decrease in glycolytic flux, oxidative phosphorylation, and ATP production rate. Irradiated salivary glands exhibit significant decreases in spare respiratory capacity and increases in mitochondrial DNA copy number at days 5 and 30 post-treatment, suggesting a mitochondrial dysfunction phenotype. These results elucidate kinetic changes in energy metabolism reprogramming of irradiated salivary glands that may underscore the chronic loss of function phenotype.

Nuclear medicine imaging methods of early radiation-induced cardiotoxicity: a ten-year systematic review

Introduction

Radiotherapy has significantly improved cancer survival rates, but it also comes with certain unavoidable complications. Breast and thoracic irradiation, for instance, can unintentionally expose the heart to radiation, leading to damage at the cellular level within the myocardial structures. Detecting and monitoring radiation-induced heart disease early on is crucial, and several radionuclide imaging techniques have shown promise in this regard.

Method

In this 10-year review, we aimed to identify nuclear medicine imaging modalities that can effectively detect early cardiotoxicity following radiation therapy. Through a systematic search on PubMed, we selected nineteen relevant studies based on predefined criteria.

Results

The data suggest that incidental irradiation of the heart during breast or thoracic radiotherapy can cause early metabolic and perfusion changes. Nuclear imaging plays a prominent role in detecting these subclinical effects, which could potentially serve as predictors of late cardiac complications.

Discussion

However, further studies with larger populations, longer follow-up periods, and specific heart dosimetric data are needed to better understand the relationship between early detection of cardiac abnormalities and radiation-induced heart disease.

Mitochondrial dysfunction at the crossroad of cardiovascular diseases and cancer

A large body of evidence indicates the existence of a complex pathophysiological relationship between cardiovascular diseases and cancer. Mitochondria are crucial organelles whose optimal activity is determined by quality control systems, which regulate critical cellular events, ranging from intermediary metabolism and calcium signaling to mitochondrial dynamics, cell death and mitophagy. Emerging data indicate that impaired mitochondrial quality control drives myocardial dysfunction occurring in several heart diseases, including cardiac hypertrophy, myocardial infarction, ischaemia/reperfusion damage and metabolic cardiomyopathies. On the other hand, diverse human cancers also dysregulate mitochondrial quality control to promote their initiation and progression, suggesting that modulating mitochondrial homeostasis may represent a promising therapeutic strategy both in cardiology and oncology. In this review, first we briefly introduce the physiological mechanisms underlying the mitochondrial quality control system, and then summarize the current understanding about the impact of dysregulated mitochondrial functions in cardiovascular diseases and cancer. We also discuss key mitochondrial mechanisms underlying the increased risk of cardiovascular complications secondary to the main current anticancer strategies, highlighting the potential of strategies aimed at alleviating mitochondrial impairment-related cardiac dysfunction and tumorigenesis. It is hoped that this summary can provide novel insights into precision medicine approaches to reduce cardiovascular and cancer morbidities and mortalities.

New Insights into the Understanding of Mechanisms of Radiation-Induced Heart Disease

OPINION STATEMENT

Cancer patients who receive high-dose thoracic radiotherapy may develop radiation-induced heart disease (RIHD). The clinical presentation of RIHD comprises coronary artery atherosclerosis, valvular disease, pericarditis, cardiomyopathy, and conduction defects. These complications have significantly reduced due to the improved radiotherapy techniques. However, such methods still could not avoid heart radiation exposure. Furthermore, people who received relatively low-dose radiation exposures have exhibited significantly elevated RIHD risks in cohort studies of atomic bomb survivors and occupational exposures. The increased potential in exposure to natural and artificial ionizing radiation sources has emphasized the necessity to understand the development of RIHD. The pathological processes of RIHD include endothelial dysfunction, inflammation, fibrosis, and hypertrophy. The underlying mechanisms may involve the changes in oxidative stress, DNA damage response, telomere erosion, mitochondrial dysfunction, epigenetic regulation, circulation factors, protein post-translational modification, and metabolites. This review will discuss the recent advances in the mechanisms of RIHD at cellular and molecular levels.

BRIDE v2: A Validated Collection of Genes Involved in the Mammalian Brain Response to Low-Dose Ionizing Radiation

There is significant interest in the response of the mammalian brain to low-dose ionizing radiation (LDIR), mainly examined by gene or protein expression, with applications in radiation safety on Earth, the atmosphere and outer space. Potential associations of molecular-level responses with sensory or cognitive defects and neurodegenerative diseases are currently under investigation. Previously, we have described a light-weight approach for the storage, analysis and distribution of relevant datasets, with the platform BRIDE. We have re-implemented the platform as BRIDE v2 on the cloud, using the bioinformatics infrastructure ELIXIR. We connected the annotated list of 3174 unique gene records with modern omics resources for downstream computational analysis. BRIDE v2 is a cloud-based platform with capabilities that enable researchers to extract, analyze, visualize as well as export the gene collection. The resource is freely available online at <http://bride-db.eu>.

Application of radiation omics in the development of adverse outcome pathway networks: an example of radiation-induced cardiovascular disease

BACKGROUND

Epidemiological studies have indicated that exposure of the heart to doses of ionizing radiation as low as 0.5 Gy increases the risk of cardiac morbidity and mortality with a latency period of decades. The damaging effects of radiation to myocardial and endothelial structures and functions have been confirmed radiobiologically at high dose, but much less is known at low dose. Integration of radiation biology and epidemiology data is a recommended approach to improve the radiation risk assessment process. The adverse outcome pathway (AOP) framework offers a comprehensive tool to compile and translate mechanistic information into pathological endpoints which may be relevant for risk assessment at the different levels of a biological system. Omics technologies enable the generation of large volumes of biological data at various levels of complexity, from molecular pathways to functional organisms. Given the quality and quantity of available data across levels of biology, omics data can be attractive sources of information for use within the AOP framework. It is anticipated that radiation omics studies could improve our understanding of the molecular mechanisms behind the adverse effects of radiation on the cardiovascular system. In this review, we explored the available omics studies on radiation-induced cardiovascular disease (CVD) and their applicability to the proposed AOP for CVD.

RESULTS

The results of 80 omics studies published on radiation-induced CVD over the past 20 years have been discussed in the context of the AOP of CVD proposed by Chauhan et al. Most of the available omics data on radiation-induced CVD are from proteomics, transcriptomics, and metabolomics, whereas few datasets were available from epigenomics and multi-omics. The omics data presented here show great promise in providing information for several key events of the proposed AOP of CVD, particularly oxidative stress, alterations of energy metabolism, extracellular matrix and vascular remodeling.

CONCLUSIONS

The omics data presented here shows promise to inform the various levels of the proposed AOP of CVD. However, the data highlight the urgent need of designing omics studies to address the knowledge gap concerning different radiation scenarios, time after exposure and experimental models. This review presents the evidence to build a qualitative omics-informed AOP and provides views on the potential benefits and challenges in using omics data to assess risk-related outcomes.

Dexamethasone is Associated With a Lower Risk of the Progression of Thoracic Aortic Calcification in Breast Cancer Survivors

Background and Purpose: Breast cancer survivors have an increased cardiovascular risk, and vascular calcification is the pathological basis of cardiovascular disease. Some factors that affect the progression of thoracic aortic calcification (TAC) in survivors are unclear, and this study aims to explore the relationship between dexamethasone or radiotherapy and the progression of TAC in survivors.

Materials and Methods: This study included 189 female patients with breast cancer, and they were divided into the progression and non-progression TAC groups. Radiation or dexamethasone doses, and related laboratory parameters were collected.

Results: The cumulative dose of dexamethasone was higher [40 (10–180) mg versus 180 (80–270) mg, p < 0.001], and the cycle was longer [4 (1–6) cycles versus 6 (4–8) cycles, p < 0.001] in the non-progression TAC group. The cumulative dose (r = −0.303, p < 0.001) and cycle (r = −0.357, p < 0.001) of dexamethasone were negatively correlated with the level of increased TAC Agatston scores in survivors. Logistic regression analysis showed that dexamethasone was a protective factor for the progression of TAC (p = 0.029, odds ratio = 0.263, 95% confidence interval = 0.08–0.872). However, there wasn’t significant relationship between radiotherapy, radiation dose, follow-up time and the progression of TAC (all p > 0.05). In addition, aorta volume was positively correlated with the level of increased TAC Agatston scores in intensity modulated radiation therapy (r = 0.460, p < 0.001).

Conclusion: Dexamethasone is associated with a lower risk of the progression of TAC in breast cancer survivors, and there’s no correlation between radiotherapy and progression of TAC, but the aorta volume may be a predictor of the severity of progression of TAC.

Activation of PPARα by Fenofibrate Attenuates the Effect of Local Heart High Dose Irradiation on the Mouse Cardiac Proteome

Radiation-induced cardiovascular disease is associated with metabolic remodeling in the heart, mainly due to the inactivation of the transcription factor peroxisome proliferator-activated receptor alpha (PPARα), thereby inhibiting lipid metabolic enzymes. The objective of the present study was to investigate the potential protective effect of fenofibrate, a known agonist of PPARα on radiation-induced cardiac toxicity. To this end, we compared, for the first time, the cardiac proteome of fenofibrate- and placebo-treated mice 20 weeks after local heart irradiation (16 Gy) using label-free proteomics. The observations were further validated using immunoblotting, enzyme activity assays, and ELISA. The analysis showed that fenofibrate restored signalling pathways that were negatively affected by irradiation, including lipid metabolism, mitochondrial respiratory chain, redox response, tissue homeostasis, endothelial NO signalling and the inflammatory status. The results presented here indicate that PPARα activation by fenofibrate attenuates the cardiac proteome alterations induced by irradiation. These findings suggest a potential benefit of fenofibrate administration in the prevention of cardiovascular diseases, following radiation exposure.

A Human 3D Cardiomyocyte Risk Model to Study the Cardiotoxic Influence of X-rays and Other Noxae in Adults

The heart tissue is a potential target of various noxae contributing to the onset of cardiovascular diseases. However, underlying pathophysiological mechanisms are largely unknown. Human stem cell-derived models are promising, but a major concern is cell immaturity when estimating risks for adults. In this study, 3D aggregates of human embryonic stem cell-derived cardiomyocytes were cultivated for 300 days and characterized regarding degree of maturity, structure, and cell composition. Furthermore, effects of ionizing radiation (X-rays, 0.1–2 Gy) on matured aggregates were investigated, representing one of the noxae that are challenging to assess. Video-based functional analyses were correlated to changes in the proteome after irradiation. Cardiomyocytes reached maximum maturity after 100 days in cultivation, judged by α-actinin lengths, and displayed typical multinucleation and branching. At this time, aggregates contained all major cardiac cell types, proven by the patch-clamp technique. Matured and X-ray-irradiated aggregates revealed a subtle increase in beat rates and a more arrhythmic sequence of cellular depolarisation and repolarisation compared to non-irradiated sham controls. The proteome analysis provides first insights into signaling mechanisms contributing to cardiotoxicity. Here, we propose an in vitro model suitable to screen various noxae to target adult cardiotoxicity by preserving all the benefits of a 3D tissue culture.

Redox interactions-induced cardiac toxicity in cancer therapy

Cancer patients undergoing radiotherapy, chemotherapy, or targeted cancer therapy are exposed to the risk of several side effects because of the heavy production of ROS by ionizing radiation or some chemotherapy drugs. Damages to DNA, mitochondria, membrane and other organelles within normal tissue cells such as cardiomyocytes and endothelial cells lead to the release of some toxins which are associated with triggering inflammatory cells to release several types of cytokines, chemokines, ROS, and RNS. The release of some molecules following radiotherapy or chemotherapy stimulates reduction/oxidation (redox) reactions. Redox reactions cause remarkable changes in the level of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Excessive production of ROS and RNS or suppression of antioxidant defense enzymes leads to damage to critical macromolecules, which may continue for long times. Increased levels of some cytokines and oxidative injury are hallmarks of heart injury following cancer therapy. Redox reactions may be involved in several heart disorders such as fibrosis, cardiomyopathy, and endothelium injury. In the current review, we explain the cellular and molecular mechanisms of redox interactions following radiotherapy, chemotherapy, and targeted cancer therapy. Afterward, we explain the evidence of the involvement of redox reactions in heart diseases.

Effects of chronic exposure to low levels of IR on Medaka (Oryzias latipes): a proteomic and bioinformatic approach

PURPOSE

Chronic exposure to ionizing radiation (IR) at low doses (<100 mGy) has been insufficiently studied to understand fully the risk to health. Relatively little knowledge exists regarding how species and healthy tissues respond at the protein level to chronic exposure to low doses of IR, and mass spectrometric-based profiling of protein expression is a powerful tool for studying changes in protein abundance.

MATERIALS AND METHODS

SDS gel electrophoresis, LC-MS/MS mass spectrometry-based approaches and bioinformatic data analytics were used to detect proteomic changes following chronic exposure to moderate/low doses of radiation in adults and normally developed Medaka fish (Oryzias latipes).

RESULTS

Significant variations in the abundance of proteins involved in thyroid hormone signaling and lipid metabolism were detected, which could be related to the gonadal regression phenotype observed after 21.04 mGy and 204.3 mGy/day exposure. The global proteomic change was towards overexpression of proteins in muscle and skin, while the opposite effect was observed in internal organs.

CONCLUSION

The present study provides information on the impacts of biologically relevant low doses of IR, which will be useful in future research for the identification of potential biomarkers of IR exposure and allow for a better assessment of radiation biosafety regulations.

Quantitative protein profiling of phenobarbital-induced drug metabolizing enzymes in rat liver by liquid chromatography mass spectrometry using formalin-fixed paraffin-embedded samples

Administration of a compound can induce drug-metabolizing enzymes (DMEs) in the liver. DME induction can affect various parameters in toxicology studies. Therefore, evaluation of DME induction is important for interpreting test compound-induced biological responses. Several methods such as measurement of hepatic microsomal DME activity using substrates, electron microscopy, or immunohistochemistry have been used; however, these methods are limited in throughput and specificity or are not quantitative. Liquid chromatography mass spectrometry (LC/MS)-based protein analysis can detect and quantify multiple proteins simultaneously per assay. Studies have shown that formalin-fixed paraffin-embedded (FFPE) samples, which are routinely collected in toxicology studies, can be used for LC/MS-based protein analysis. To validate the utility of LC/MS using FFPE samples for quantitative evaluation of DME induction, we treated rats with a DME inducer, phenobarbital, and compared the protein expression levels of 13 phase-I and 11 phase-II DMEs between FFPE and fresh frozen hepatic samples using LC/MS. A good correlation between data from FFPE and frozen samples was obtained after analysis. In FFPE and frozen samples, the expression of 6 phase-I and 8 phase-II DMEs showed a similar significant increase and a prominent rise in Cyp2b2 and Cyp3a1 levels. In addition, LC/MS data were consistent with the measurement of microsomal DME activities. These results suggest that LC/MS-based protein expression analysis using FFPE samples is as effective as that using frozen samples for detecting DME induction.

Brain Damage and Patterns of Neurovascular Disorder after Ionizing Irradiation. Complications in Radiotherapy and Radiation Combined Injury

Exposure to ionizing radiation, mechanical trauma, toxic chemicals or infections, or combinations thereof (i.e., combined injury) can induce organic injury to brain tissues, the structural disarrangement of interactive networks of neurovascular and glial cells, as well as on arrays of the paracrine and systemic destruction. This leads to subsequent decline in cognitive capacity and decompensation of mental health. There is an ongoing need for improvement in mitigating and treating radiation- or combined injury-induced brain injury. Cranial irradiation per se can cause a multifactorial encephalopathy that occurs in a radiation dose- and time-dependent manner due to differences in radiosensitivity among the various constituents of brain parenchyma and vasculature. Of particular concern are the radiosensitivity and inflammation susceptibility of: 1. the neurogenic and oligodendrogenic niches in the subependymal and hippocampal domains; and 2. the microvascular endothelium. Thus, cranial or total-body irradiation can cause a plethora of biochemical and cellular disorders in brain tissues, including: 1. decline in neurogenesis and oligodendrogenesis; 2. impairment of the blood-brain barrier; and 3. ablation of vascular capillary. These changes, along with cerebrovascular inflammation, underlie different stages of encephalopathy, from the early protracted stage to the late delayed stage. It is evident that ionizing radiation combined with other traumatic insults such as penetrating wound, burn, blast, systemic infection and chemotherapy, among others, can exacerbate the radiation sequelae (and vice versa) with increasing severity of neurogenic and microvascular patterns of radiation brain damage.

Role of Commensal Microbes in the γ-Ray Irradiation-Induced Physiological Changes in Drosophila melanogaster

Ionizing radiation induces biological/physiological changes and affects commensal microbes, but few studies have examined the relationship between the physiological changes induced by irradiation and commensal microbes. This study investigated the role of commensal microbes in the γ-ray irradiation-induced physiological changes in Drosophila melanogaster. The bacterial load was increased in 5 Gy irradiated flies, but irradiation decreased the number of operational taxonomic units. The mean lifespan of conventional flies showed no significant change by irradiation, whereas that of axenic flies was negatively correlated with the radiation dose. γ-Ray irradiation did not change the average number of eggs in both conventional and axenic flies. Locomotion of conventional flies was decreased after 5 Gy radiation exposure, whereas no significant change in locomotion activity was detected in axenic flies after irradiation. γ-Ray irradiation increased the generation of reactive oxygen species in both conventional and axenic flies, but the increase was higher in axenic flies. Similarly, the amounts of mitochondria were increased in irradiated axenic flies but not in conventional flies. These results suggest that axenic flies are more sensitive in their mitochondrial responses to radiation than conventional flies, and increased sensitivity leads to a reduced lifespan and other physiological changes in axenic flies.

Chronic Occupational Exposure to Ionizing Radiation Induces Alterations in the Structure and Metabolism of the Heart: A Proteomic Analysis of Human Formalin-Fixed Paraffin-Embedded (FFPE) Cardiac Tissue

Epidemiological studies on workers employed at the Mayak plutonium enrichment plant have demonstrated an association between external gamma ray exposure and an elevated risk of ischemic heart disease (IHD). In a previous study using fresh-frozen post mortem samples of the cardiac left ventricle of Mayak workers and non-irradiated controls, we observed radiation-induced alterations in the heart proteome, mainly downregulation of mitochondrial and structural proteins. As the control group available at that time was younger than the irradiated group, we could not exclude age as a confounding factor. To address this issue, we have now expanded our study to investigate additional samples using archival formalin-fixed paraffin-embedded (FFPE) tissue. Importantly, the control group studied here is older than the occupationally exposed (>500 mGy) group. Label-free quantitative proteomics analysis showed that proteins involved in the lipid metabolism, sirtuin signaling, mitochondrial function, cytoskeletal organization, and antioxidant defense were the most affected. A histopathological analysis elucidated large foci of fibrotic tissue, myocardial lipomatosis and lymphocytic infiltrations in the irradiated samples. These data highlight the suitability of FFPE material for proteomics analysis. The study confirms the previous results emphasizing the role of adverse metabolic changes in the radiation-associated IHD. Most importantly, it excludes age at the time of death as a confounding factor.

Rac1: A potential radiosensitization target of human nasopharyngeal carcinoma CNE2 cells

Radiotherapy has a high cure rate for early nasopharyngeal carcinoma(NPC). However, the radiation resistance of poorly differentiated NPC cells impacts the effectiveness of treatment of early-stage NPC patients. Here, we explored the relationship between Ras-related C3 botulinum toxin substrate 1(Rac1) expression and NPC radiosensitivity. In vitro and in vivo studies revealed that upregulation of Rac1, when combined with X-ray treatment, increased growth inhibition and induced remarkable morphological changes and apoptosis in CNE2 cells. Furthermore, rupturing of the cell and nuclear membranes, degeneration of the cristae and significant swelling of the mitochondria were observed, which were consistent with the high apoptotic rate. The Rac1(+) cells exhibited approximately 50% more migration compared with that of the NC and Rac1(-) cells. The overexpression of Rac1 can increase the radiation sensitivity of NPC CNE2 cells, and the mechanism may be closely related to the oxidative damage of mitochondria. Rac1 might be a potential target for radiosensitization in poorly differentiated NPC.

Gamma-irradiation-induced testicular oxidative stress and apoptosis: Mitigation by l-carnitine

The current study evaluated the potential ameliorative and protective impacts of l-carnitine (L-CAR) against γ-irradiation (RAD)-induced oxidative stress and apoptosis in mice testes. Male Swiss mice were allocated into four groups (n = 7). Group 1 served as a control that received saline intraperitoneally (IP). Group 2 received L-CAR (10 mg/kg bw/day; IP in saline) for 17 days. Group 3 received saline for 17 days and on day 7 exposed to RAD at a dose of 0.1 Gy per day for consecutive 10 days. Group 4 (L-CAR + RAD), received L-CAR same as in group 2 and on day 7 exposed to RAD for consecutive 10 days. Testicular antioxidants (malondialdehyde, MDA; γ-glutamyl-cysteine synthetase, gGCS; and catalase) were altered by γ-irradiation. Preadministration of L-CAR protected γ-irradiated mice from altered changes induced by γ-irradiation. γ-Irradiation affected the mRNA expression of pro-apoptotic, apoptotic, and anti-apoptotic genes (c-jun, c-fos, Bcl-xl, caspase-3, and BAX). All altered genes were ameliorated by prior l-carnitine administration to γ-irradiated mice. Testicular cells showed deformities and edema with congestion in seminiferous tubules and strong immunoreactivity for caspase-9 and a decrease in immunoreactivity of Bcl-2 in histological and immunohistochemical examination. Prior administration of L-CAR to γ-irradiated mice protected this group from reported changes in caspase-9 and Bcl-2 immunostaining. In conclusion, the current study provides evidence for the protective and ameliorative impacts of L-CAR against γ-irradiation-induced testicular oxidative stress and apoptosis at biochemical, molecular, and cellular levels.

Acute total body ionizing gamma radiation induces long-term adverse effects and immediate changes in cardiac protein oxidative carbonylation in the rat

Radiation-induced heart disease presents a significant challenge in the event of an accidental radiation exposure as well as to cancer patients who receive acute doses of irradiation as part of radiation therapy. We utilized the spontaneously hypertensive Wistar-Kyoto rat model, previously shown to demonstrate drug-induced cardiomyopathy, to evaluate the acute and long-term effects of sub-lethal total body gamma irradiation at two, four, and fifty-two weeks. We further examined irreversible oxidative protein carbonylation in the heart immediately following irradiation in the normotensive Wistar-Kyoto rat. Both males and females sustained weight loss and anemic conditions compared to untreated controls over a one-year period as reflected by reduced body weight and low red blood cell count. Increased inflammation was detected by elevated IL-6 serum levels selectively in males at four weeks. Serum cardiac troponin T and I analyses revealed signs of cardiomyopathy at earlier timepoints, but high variability was observed, especially at one year. Echocardiography at two weeks following 5.0Gy treatment revealed a significant decrease in cardiac output in females and a significant decrease in both diastolic and systolic volumes in males. Following 10.0Gy irradiation in the normotensive Wistar-Kyoto rat, the heart tissue showed an increase in total protein oxidative carbonylation accompanied by DNA damage indicated by an increase in γ-H2AX. Using proteomic analyses, we identified several novel proteins which showed a marked difference in carbonylation including those of mitochondrial origin and most notably, cardiac troponin T, one of the key proteins involved in cardiomyocyte contractility. Overall, we present findings of acute oxidative protein damage, DNA damage, cardiac troponin T carbonylation, and long-term cardiomyopathy in the irradiated animals.

Adverse outcome pathways for ionizing radiation and breast cancer involve direct and indirect DNA damage, oxidative stress, inflammation, genomic instability, and interaction with hormonal regulation of the breast

Knowledge about established breast carcinogens can support improved and modernized toxicological testing methods by identifying key mechanistic events. Ionizing radiation (IR) increases the risk of breast cancer, especially for women and for exposure at younger ages, and evidence overall supports a linear dose-response relationship. We used the Adverse Outcome Pathway (AOP) framework to outline and evaluate the evidence linking ionizing radiation with breast cancer from molecular initiating events to the adverse outcome through intermediate key events, creating a qualitative AOP. We identified key events based on review articles, searched PubMed for recent literature on key events and IR, and identified additional papers using references. We manually curated publications and evaluated data quality. Ionizing radiation directly and indirectly causes DNA damage and increases production of reactive oxygen and nitrogen species (RONS). RONS lead to DNA damage and epigenetic changes leading to mutations and genomic instability (GI). Proliferation amplifies the effects of DNA damage and mutations leading to the AO of breast cancer. Separately, RONS and DNA damage also increase inflammation. Inflammation contributes to direct and indirect effects (effects in cells not directly reached by IR) via positive feedback to RONS and DNA damage, and separately increases proliferation and breast cancer through pro-carcinogenic effects on cells and tissue. For example, gene expression changes alter inflammatory mediators, resulting in improved survival and growth of cancer cells and a more hospitable tissue environment. All of these events overlap at multiple points with events characteristic of "background" induction of breast carcinogenesis, including hormone-responsive proliferation, oxidative activity, and DNA damage. These overlaps make the breast particularly susceptible to ionizing radiation and reinforce that these biological activities are important characteristics of carcinogens. Agents that increase these biological processes should be considered potential breast carcinogens, and predictive methods are needed to identify chemicals that increase these processes. Techniques are available to measure RONS, DNA damage and mutation, cell proliferation, and some inflammatory proteins or processes. Improved assays are needed to measure GI and chronic inflammation, as well as the interaction with hormonally driven development and proliferation. Several methods measure diverse epigenetic changes, but it is not clear which changes are relevant to breast cancer. In addition, most toxicological assays are not conducted in mammary tissue, and so it is a priority to evaluate if results from other tissues are generalizable to breast, or to conduct assays in breast tissue. Developing and applying these assays to identify exposures of concern will facilitate efforts to reduce subsequent breast cancer risk.

Adverse outcome pathways for ionizing radiation and breast cancer involve direct and indirect DNA damage, oxidative stress, inflammation, genomic instability, and interaction with hormonal regulation of the breast

Knowledge about established breast carcinogens can support improved and modernized toxicological testing methods by identifying key mechanistic events. Ionizing radiation (IR) increases the risk of breast cancer, especially for women and for exposure at younger ages, and evidence overall supports a linear dose-response relationship. We used the Adverse Outcome Pathway (AOP) framework to outline and evaluate the evidence linking ionizing radiation with breast cancer from molecular initiating events to the adverse outcome through intermediate key events, creating a qualitative AOP. We identified key events based on review articles, searched PubMed for recent literature on key events and IR, and identified additional papers using references. We manually curated publications and evaluated data quality. Ionizing radiation directly and indirectly causes DNA damage and increases production of reactive oxygen and nitrogen species (RONS). RONS lead to DNA damage and epigenetic changes leading to mutations and genomic instability (GI). Proliferation amplifies the effects of DNA damage and mutations leading to the AO of breast cancer. Separately, RONS and DNA damage also increase inflammation. Inflammation contributes to direct and indirect effects (effects in cells not directly reached by IR) via positive feedback to RONS and DNA damage, and separately increases proliferation and breast cancer through pro-carcinogenic effects on cells and tissue. For example, gene expression changes alter inflammatory mediators, resulting in improved survival and growth of cancer cells and a more hospitable tissue environment. All of these events overlap at multiple points with events characteristic of "background" induction of breast carcinogenesis, including hormone-responsive proliferation, oxidative activity, and DNA damage. These overlaps make the breast particularly susceptible to ionizing radiation and reinforce that these biological activities are important characteristics of carcinogens. Agents that increase these biological processes should be considered potential breast carcinogens, and predictive methods are needed to identify chemicals that increase these processes. Techniques are available to measure RONS, DNA damage and mutation, cell proliferation, and some inflammatory proteins or processes. Improved assays are needed to measure GI and chronic inflammation, as well as the interaction with hormonally driven development and proliferation. Several methods measure diverse epigenetic changes, but it is not clear which changes are relevant to breast cancer. In addition, most toxicological assays are not conducted in mammary tissue, and so it is a priority to evaluate if results from other tissues are generalizable to breast, or to conduct assays in breast tissue. Developing and applying these assays to identify exposures of concern will facilitate efforts to reduce subsequent breast cancer risk.

Relationship Between Changes in Myocardial F-18 Fluorodeoxyglucose Uptake and Radiation Dose After Adjuvant Three-Dimensional Conformal Radiotherapy in Patients with Breast Cancer

This study aimed to assess the relationship between radiation dose and changes in the irradiated myocardial F-18 fluorodeoxyglucose (FDG) uptake after radiotherapy (RT) in breast cancer patients. The data of 55 patients with left and 48 patients with right breast cancer who underwent curative surgical resection and adjuvant three-dimensional conformal RT and staging (PET1), post-adjuvant chemotherapy (PET2), post-RT (PET3), and surveillance (PET4) FDG positron emission tomography/computed tomography (PET/CT) were retrospectively reviewed. The median interval between PET1 and curative surgical resection, between the end of adjuvant chemotherapy and PET2, between the end of RT and PET3, and between the end of RT and PET4 were five days, 13 days, 132 days, and 353 days, respectively. The myocardial-to-blood pool uptake ratio was measured in all patients. For patients with left breast cancer, the 30 Gy- (30 Gy) and 47.5 Gy-irradiated myocardium-to-low-irradiated myocardium (47.5 Gy) FDG uptake ratios were additionally measured. There were no differences in the myocardial-to-blood pool uptake ratios between left and right breast cancer on all PET scans. For left breast cancer, higher 30 Gy and 47.5 Gy uptake ratios were observed on PET3 than on PET1 and PET2. Both uptake ratios decreased on PET4 compared to PET3, but, were still higher compared to PET1. On PET3 and PET4, the 47.5 Gy were higher than the 30 Gy uptake ratios, while there were no differences between them on PET1 and PET2. Although the whole myocardium FDG uptake showed no significant change, the irradiated myocardium FDG uptake significantly increased after RT and was related to radiation dose to the myocardium in breast cancer patients. These results might be an imaging evidence that supports the increased risk of heart disease after RT in patients with left breast cancer.

The Role of Mitochondrial Dysfunction in Radiation-Induced Heart Disease: From Bench to Bedside

Radiation is a key modality in the treatment of many cancers; however, it can also affect normal tissues adjacent to the tumor, leading to toxic effects. Radiation to the thoracic region, such as that received as part of treatment for breast and lung cancer, can result in incidental dose to the heart, leading to cardiac dysfunction, such as pericarditis, coronary artery disease, ischemic heart disease, conduction defects, and valvular dysfunction. The underlying mechanisms for these morbidities are currently being studied but are not entirely understood. There has been increasing focus on the role of radiation-induced mitochondrial dysfunction and the ensuing impact on various cardiac functions in both preclinical models and in humans. Cardiomyocyte mitochondria are critical to cardiac function, and mitochondria make up a substantial part of a cardiomyocyte's volume. Mitochondrial dysfunction can also alter other cell types in the heart. This review summarizes several factors related to radiation-induced mitochondrial dysfunction in cardiomyocytes and endothelial cells. These factors include mitochondrial DNA mutations, oxidative stress, alterations in various mitochondrial function-related transcription factors, and apoptosis. Through improved understanding of mitochondria-dependent mechanisms of radiation-induced heart dysfunction, potential therapeutic targets can be developed to assist in prevention and treatment of radiation-induced heart damage.

Protective effect of N-acetyl cysteine against radiotherapy-induced cardiac damage

Purpose: Although radiotherapy (RT) is an important component of cancer treatment, it induces adverse tissue reactions in the around of cancer tissue. Therefore, radioprotectives are needed to protect normal tissues. The aim of this study was to investigate the radioprotective effect of N-acetylcysteine (NAC) on RT-induced cardiac damage in rats for the acute term.Materials and methods: The animals were divided into four groups. The rats in control group were injected with saline for 7 d; the rats in NAC group were injected NAC at dose of 240 mg/kg d for 7 d; the rats in RT group were injected with saline for 7 d plus was irradiated 1 h after the last injection and the rats in NAC + RT group were injected with NAC for 7 d and irradiated 1 h after the last NAC dose. The electrocardiogram was recorded and evaluated PR interval, QRS duration, QT interval, T wave alterations and heart rate. Serum interleukin-4, interleukin-6, tumor necrosis factor-alpha, interleukin 1 beta, galectin-3 levels and creatine kinase and creatine kinase isoenzyme-MB activities were determined in all groups. Also, tissue malondialdehyde (MDA) and nitric oxide levels, superoxide dismutase, catalase and glutathione peroxidase activities were determined. In addition, histological changes of heart were evaluated. All measurements were performed 24 h after RT.Results: In the RT group, findings supporting cardiac injury were observed in the electrocardiogram. Also, cytokine levels and oxidative stress were significantly increased. Pretreatment of rats with NAC ameliorated cardiac injury induced by RT.Conclusions: Our findings suggested that NAC may be a potential radioprotector which is capable of preventing cardiac damage.

Irradiation impairs mitochondrial function and skeletal muscle oxidative capacity: significance for metabolic complications in cancer survivors

BACKGROUND

Metabolic complications are highly prevalent in cancer survivors treated with irradiation but the underlying mechanisms remain unknown.

METHODS

Chow or high fat-fed C57Bl/6J mice were irradiated (6Gy) before investigating the impact on whole-body or skeletal muscle metabolism and profiling their lipidomic signature. Using a transgenic mouse model (Tg:Pax7-nGFP), we isolated muscle progenitor cells (satellite cells) and characterised their metabolic functions. We recruited childhood cancer survivors, grouped them based on the use of total body irradiation during their treatment and established their lipidomic profile.

RESULTS

In mice, irradiation delayed body weight gain and impaired fat pads and muscle weights. These changes were associated with impaired whole-body fat oxidation in chow-fed mice and altered ex vivo skeletal muscle fatty acid oxidation, potentially due to a reduction in oxidative fibres and reduced mitochondrial enzyme activity. Irradiation led to fasting hyperglycaemia and impaired glucose uptake in isolated skeletal muscles. Cultured satellite cells from irradiated mice showed decreased fatty acid oxidation and reduced glucose uptake, recapitulating the host metabolic phenotype. Irradiation resulted in a remodelling of lipid species in skeletal muscles, with the extensor digitorum longus muscle being particularly affected. A large number of lipid species were reduced, with several of these species showing a positive correlation with mitochondrial enzymes activity. In cancer survivors exposed to irradiation, we found a similar decrease in systemic levels of most lipid species, and lipid species that increased were positively correlated with insulin resistance (HOMA-IR).

CONCLUSION

Irradiation leads to long-term alterations in body composition, and lipid and carbohydrate metabolism in skeletal muscle, and affects muscle progenitor cells. Such changes result in persistent impairment of metabolic functions, providing a new mechanism for the increased prevalence of metabolic diseases reported in irradiated individuals. In this context, changes in the lipidomic signature in response to irradiation could be of diagnostic value.

Radiation metabolomics in the quest of cardiotoxicity biomarkers: the review

Purpose: Ionizing radiation is a risk factor to the whole organism, including the heart. Cardiac damage is considered to be a late effect of radiation exposure. While the acute cardiotoxicity of high doses is well characterized, the knowledge about nature and magnitude of the cardiac risk following lower doses exposure is incomplete. It has been shown that the cardiotoxic effects of radiation are source-, dose- and time-dependent. This paper provides an overview on these dependencies with regard to the molecular responses at the cellular and tissue levels. Main focus is put on the Nuclear Magnetic Resonance (NMR)-based and Mass Spectrometry (MS)-based metabolomic approaches in search of toxicity markers of relatively small doses of radiation.Conclusions: Available literature indicates that radiation exposure affects metabolites associated with: energy production, degradation of proteins and cell membranes, expression of proteins and stress response. Such effects are common for both animal and human studies. However, the specific metabolic response depends on several factors, including the examined organ. Radiation metabolomics can be used to explain the mechanisms of development of radiation-induced heart disease and to find an organ-specific biomarker of radiation exposure. The main aim of this review was to collect the information on the human cardiotoxicity biomarkers. In addition it also summarizes results of the studies on the metabolic responses to ionizing radiation for other organs, as well as the comparative data concerning animal studies.

Differential modification of the C. elegans proteome in response to acute and chronic gamma radiation: Link with reproduction decline

Emission of ionizing radiation (IR) in the environment is a natural phenomenon which can be enhanced by human activities. Ecosystems are then chronically exposed to IR. But environmental risk assessment of chronic exposure suffers from a lack of knowledge. Extrapolation of data from acute to chronic exposure is not always relevant, and can lead to uncertainties as effects could be different between the two irradiation modes, especially regarding reproduction endpoint, which is an ecologically relevant parameter. In the present study, we decided to refine the understanding of the molecular mechanisms involved in response to acute and chronic γ-irradiation by a global proteome label free LC-MS/MS analysis. C. elegans were exposed to 3 common cumulated radiation doses for acute or chronic exposure condition and global modification of the proteome was studied. This analysis of protein expression has demonstrated the modulation of proteins involved in regulatory biological processes such as lipid transport, DNA replication, germ cell development, apoptosis, ion transport, cuticle development, and aging at lower doses than those for which individual effects on reproduction have been previously observed. Thus, these proteins could constitute early and sensitive markers of radio-induced reprotoxicity; more specifically HAT-1, RPS-19 in acute and VIT-3 for chronic conditions that are expressed in a dose-dependent manner. Finally, to focus on reproduction process, this analysis showed either repression or overexpression of 12 common proteins in organisms exposed to acute or chronic irradiation, respectively. These proteins include the vitellogenin cluster notably involved in lipid transport and oocyte maturation and proteins involved in cuticle development and molting i.e. COL-14, GLF-1, NOAH-1, NOAH-2, ACN-1. These results show that protein expression modulation is a sensitive and predictive marker of radio-induced reproductive effects, but also highlight limitation of data extrapolation from acute to chronic exposure for environmental risk assessment.

An Effective Protocol for Proteome Analysis of Medaka (Oryzias latipes) after Acute Exposure to Ionizing Radiation

All terrestrial organisms are subject to evolutionary pressures associated with natural sources of ionizing radiation (IR). The legacy of human-induced IR associated with energy, weapons production, medicine, and research has changed the distribution and magnitude of these evolutionary pressures. To date, no study has systematically examined the effects of environmentally relevant doses of radiation exposure across an organismal proteome. This void in knowledge has been due, in part, to technological deficiencies that have hampered quantifiable environmentally relevant IR doses and sensitive detection of proteomic responses. Here, we describe a protocol that addresses both needs, combining quantifiable IR delivery with a reliable method to yield proteomic comparisons of control and irradiated Medaka fish. Exposures were conducted at the Savannah River Ecology Laboratory (SREL, in Aiken, SC), where fish were subsequently dissected into three tissue sets (carcasses, organs and intestines) and frozen until analysis. Tissue proteins were extracted, resolved by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE), and each sample lane was divided into ten equal portions. Following in-gel tryptic digestion, peptides released from each gel portion were identified and quantified by Liquid Chromatography-Mass Spectrometry (LC-MS/MS) to obtain the most complete, comparative study to date of proteomic responses to environmentally relevant doses of IR. This method provides a simple approach for use in ongoing epidemiologic studies of chronic exposure to environmentally relevant levels of IR and should also serve well in physiological, developmental, and toxicological studies.

Investigation of serum proteome homeostasis during radiation therapy by a quantitative proteomics approach

The purpose of the present study is to analyze the serum proteome of patients receiving Radiation Therapy (RT) at different stages of their treatment to discovery candidate biomarkers of the radiation-induced skin lesions and the molecular pathways underlying the radiation signatures. Six stages of RT treatment were monitored from patients treated because of brain cancer: before starting the treatment, during the treatment (four time points), and at 4 weeks from the last RT dose. Serum samples were analyzed by a proteomics approach based on the Data Independent Acquisition (DIA) mass spectrometry (MS). RT induced clear changes in the expression levels of 36 serum proteins. Among these, 25 proteins were down- or up-regulated significantly before the emergence of skin lesions. Some of these were still deregulated after the completion of the treatment. Few days before the appearance of the skin lesions, the levels of some proteins involved in the wound healing processes were down-regulated. The pathway analysis indicated that after partial body irradiation, the expression levels of proteins functionally involved in the acute inflammatory and immune response, lipoprotein process and blood coagulation, were deregulated.

Proteomic Changes in Mouse Spleen after Radiation-Induced Injury and its Modulation by Gamma-Tocotrienol

Gamma-tocotrienol (GT3), a naturally occurring vitamin E isomer, a promising radioprotector, has been shown to protect mice against radiation-induced hematopoietic and gastrointestinal injuries. We analyzed changes in protein expression profiles of spleen tissue after GT3 treatment in mice exposed to gamma radiation to gain insights into the molecular mechanism of radioprotective efficacy. Male CD2F1 mice, 12-to-14 weeks old, were treated with either vehicle or GT3 at 24 h prior to 7 Gy total-body irradiation. Nonirradiated vehicle, nonirradiated GT3 and age-matched naïve animals were used as controls. Blood and tissues were harvested on days 0, 1, 2, 4, 7, 10 and 14 postirradiation. High-resolution mass-spectrometry-based radioproteomics was used to identify differentially expressed proteins in spleen tissue with or without drug treatment. Subsequent bioinformatic analyses helped delineate molecular markers of biological pathways and networks regulating the cellular radiation responses in spleen. Our results show a robust alteration in spleen proteomic profiles including upregulation of the Wnt signaling pathway and actin-cytoskeleton linked proteins in mediating the radiation injury response in spleen. Furthermore, we show that 24 h pretreatment with GT3 attenuates radiation-induced hematopoietic injury in the spleen by modulating various cell signaling proteins. Taken together, our results show that the radioprotective effects of GT3 are mediated, via alleviation of radiation-induced alterations in biochemical pathways, with wide implications on overall hematopoietic injury.

Cardioprotective effect of zingerone against oxidative stress, inflammation, and apoptosis induced by cisplatin or gamma radiation in rats

Despite their clinical benefits in cancer treatment, the deleterious effects on heart following chemo/radiotherapy are of increasing importance. Zingerone, a natural polyphenol, possesses multiple biological activities, such as antioxidant and anti-inflammatory. Thus, the current study was designed to assess the potential cardioprotective effects of zingerone against cisplatin or γ-radiation. Zingerone was given by intragastric intubation (25 mg/kg) daily for three successive weeks prior to the induction of cardiotoxicity using a single dose of cisplatin (20 mg/kg, i.p.) or a whole body γ-irradiation at a single dose of 6 Gy. Zingerone pre-treatment significantly reduced the abnormalities in heart histology and the increase in the cardiotoxicity indices, serum lactate dehydrogenase, and creatine kinase-MB activities, as well as plasma cardiac troponin T and B-natriuretic peptide, induced by cisplatin or γ-radiation. Further, zingerone, except for superoxide dismutase, notably ameliorated the state of oxidative stress as evidenced by a significant decrease in malondialdehyde level accompanied with a significant increase in the reduced glutathione content and catalase activity. Additionally, zingerone mitigated the increase in the inflammatory markers including serum level of tumor necrosis factor-alpha, cardiac myeloperoxidase activity, and cyclooxygenase-2 protein expression. Moreover, zingerone alleviated the elevation of caspase-3 gene expression and the prominent nuclear DNA fragmentation and attenuated the decrease in mitochondrial complexes' activities. This study sheds the light on a probable protective role of zingerone as an antioxidant, anti-inflammatory, and antiapoptotic agent against cisplatin- or γ-radiation-induced cardiotoxicity and holds a potential in regard to therapeutic intervention for chemo/radiotherapy mediated cardiac damage.

A dose-dependent perturbation in cardiac energy metabolism is linked to radiation-induced ischemic heart disease in Mayak nuclear workers

Epidemiological studies show a significant increase in ischemic heart disease (IHD) incidence associated with total external gamma-ray dose among Mayak plutonium enrichment plant workers. Our previous studies using mouse models suggest that persistent alteration of heart metabolism due to the inhibition of peroxisome proliferator-activated receptor (PPAR) alpha accompanies cardiac damage after high doses of ionising radiation. The aim of the present study was to elucidate the mechanism of radiation-induced IHD in humans. The cardiac proteome response to irradiation was analysed in Mayak workers who were exposed only to external doses of gamma rays. All participants were diagnosed during their lifetime with IHD that also was the cause of death. Label-free quantitative proteomics analysis was performed on tissue samples from the cardiac left ventricles of individuals stratified into four radiation dose groups (0 Gy, < 100 mGy, 100–500 mGy, and > 500 mGy). The groups could be separated using principal component analysis based on all proteomics features. Proteome profiling showed a dose-dependent increase in the number of downregulated mitochondrial and structural proteins. Both proteomics and immunoblotting showed decreased expression of several oxidative stress responsive proteins in the irradiated hearts. The phosphorylation of transcription factor PPAR alpha was increased in a dose-dependent manner, which is indicative of a reduction in transcriptional activity with increased radiation dose. These data suggest that chronic external radiation enhances the risk for IHD by inhibiting PPAR alpha and altering the expression of mitochondrial, structural, and antioxidant components of the heart.

Cardiovascular Disease and Breast Cancer: Where These Entities Intersect: A Scientific Statement From the American Heart Association

Cardiovascular disease (CVD) remains the leading cause of mortality in women, yet many people perceive breast cancer to be the number one threat to women's health. CVD and breast cancer have several overlapping risk factors, such as obesity and smoking. Additionally, current breast cancer treatments can have a negative impact on cardiovascular health (eg, left ventricular dysfunction, accelerated CVD), and for women with pre-existing CVD, this might influence cancer treatment decisions by both the patient and the provider. Improvements in early detection and treatment of breast cancer have led to an increasing number of breast cancer survivors who are at risk of long-term cardiac complications from cancer treatments. For older women, CVD poses a greater mortality threat than breast cancer itself. This is the first scientific statement from the American Heart Association on CVD and breast cancer. This document will provide a comprehensive overview of the prevalence of these diseases, shared risk factors, the cardiotoxic effects of therapy, and the prevention and treatment of CVD in breast cancer patients.

GRK2 moderates the acute mitochondrial damage to ionizing radiation exposure by promoting mitochondrial fission/fusion

The modern understanding of the G protein-coupled receptor kinase 2 has grown towards the definition of a stress protein, for its ability to rapidly compartmentalize within the cell in response to acute stimulation. Also, mitochondria can be regulated by GRK2 localization. We show that Ionizing Radiation (IR) exposure acutely damages mitochondria regarding mass, morphology, and respiration, with recovery in a framework of hours. This phenomenon is actively regulated by GRK2, whose overexpression results to be protective, and reciprocally, deletion accelerates degenerative processes. The regulatory effects of the kinase involve a new interactome that includes binding HSP90 and binding and phosphorylation of the key molecules involved in the process of mitochondrial fusion and recovery: MFN-1 and 2.

Transcriptomic and proteomic analysis of mouse radiation-induced acute myeloid leukaemia (AML)

A combined transcriptome and proteome analysis of mouse radiation-induced AMLs using two primary AMLs, cell lines from these primaries, another cell line and its in vivo passage is reported. Compared to haematopoietic progenitor and stem cells (HPSC), over 5000 transcriptome alterations were identified, 2600 present in all materials. 55 and 3 alterations were detected in the proteomes of the cell lines and primary/in vivo passage material respectively, with one common to all materials. In cell lines, approximately 50% of the transcriptome changes are related to adaptation to cell culture, and in the proteome this proportion was higher. An AML 'signature' of 17 genes/proteins commonly deregulated in primary AMLs and cell lines compared to HPSCs was identified and validated using human AML transcriptome data. This also distinguishes primary AMLs from cell lines and includes proteins such as Coronin 1, pontin/RUVBL1 and Myeloperoxidase commonly implicated in human AML. C-Myc was identified as having a key role in radiation leukaemogenesis. These data identify novel candidates relevant to mouse radiation AML pathogenesis, and confirm that pathways of leukaemogenesis in the mouse and human share substantial commonality.

Heart in space: effect of the extraterrestrial environment on the cardiovascular system

National space agencies and private corporations aim at an extended presence of humans in space in the medium to long term. Together with currently suboptimal technology, microgravity and cosmic rays raise health concerns about deep-space exploration missions. Both of these physical factors affect the cardiovascular system, whose gravity-dependence is pronounced. Heart and vascular function are, therefore, susceptible to substantial changes in weightlessness. The altered cardiovascular function in space causes physiological problems in the postflight period. A compromised cardiovascular system can be excessively vulnerable to space radiation, synergistically resulting in increased damage. The space radiation dose is significantly lower than in patients undergoing radiotherapy, in whom cardiac damage is well-documented following cancer therapy in the thoracic region. Nevertheless, epidemiological findings suggest an increased risk of late cardiovascular disease even with low doses of radiation. Moreover, the peculiar biological effectiveness of heavy ions in cosmic rays might increase this risk substantially. However, whether radiation-induced cardiovascular effects have a threshold at low doses is still unclear. The main countermeasures to mitigate the effect of the space environment on cardiac function are physical exercise, antioxidants, nutraceuticals, and radiation shielding.

Proteomics landscape of radiation-induced cardiovascular disease: somewhere over the paradigm

INTRODUCTION

Epidemiological studies clearly show that thoracic or whole body exposure to ionizing radiation increases the risk of cardiac morbidity and mortality. Radiation-induced cardiovascular disease (CVD) has been intensively studied during the last ten years but the underlying molecular mechanisms are still poorly understood. Areas covered: Heart proteomics is a powerful tool holding promise for the future research. The central focus of this review is to compare proteomics data on radiation-induced CVD with data arising from proteomics of healthy and diseased cardiac tissue in general. In this context we highlight common and unique features of radiation-related and other heart pathologies. Future prospects and challenges of the field are discussed. Expert commentary: Data from comprehensive cardiac proteomics have deepened the knowledge of molecular mechanisms involved in radiation-induced cardiac dysfunction. State-of-the-art proteomics has the potential to identify novel diagnostic and therapeutic markers of this disease.

Impact of Ionizing Radiation on the Cardiovascular System: A Review

Radiation therapy has become one of the main forms of treatment for various types of cancers. Cancer patients previously treated with high doses of radiation are at a greater risk to develop cardiovascular complications later in life. The heart can receive varying doses of radiation depending on the type of therapy and can even reach doses in the range of 17 Gy. Multiple studies have highlighted the role of oxidative stress and inflammation in radiation-induced cardiovascular damage. Doses of ionizing radiation below 200 mGy, however, have been shown to have beneficial effects in some experimental models of radiation-induced damage, but low-dose effects in the heart is still debated. Low-dose radiation may promote heart health and reduce damage from oxidative stress and inflammation, however there are few studies focusing on the impact of low-dose radiation on the heart. In this review, we summarize recent studies from animal models and human data focusing on the effects and mechanism(s) of action of radiation-induced damage to the heart, as well as the effects of high and low doses of radiation and dose rates.

Bone marrow mesenchymal stem cell transplantation improves radiation-induced heart injury through DNA damage repair in rat model

Radiotherapy is an effective form of therapy for most thoracic malignant tumors. However, myocardial injury resulting from the high doses of radiation is a severe complication. Here we aimed to study the possibility of reducing radiation-induced myocardial injury with mesenchymal stem cell (MSC) transplantation. We used MSCs extracted from bone marrow (BMSCs) to transplant via the tail vein into a radiation-induced heart injury (RIHI) rat model. The rats were divided into six groups: a Sham group, an IRR (irradiation) group, and four IRR + BMSCs transplantation groups obtained at different time points. After irradiation, BMSC transplantation significantly enhanced the cardiac function in rats. By analyzing the expression of PPAR-α, PPAR-γ, TGF-β, IL-6, and IL-8, we found that BMSC transplantation alleviated radiation-induced myocardial fibrosis and decreased the inflammatory reaction. Furthermore, we found that expression of γ-H2AX, XRCC4, DNA ligase4, and TP53BP1, which are associated with DNA repair, was up-regulated, along with increased secretion of growth factors SDF-1, CXCR4, VEGF, and IGF in rat myocardium in the IRR + BMSCs transplantation groups compared with the IRR group. Thus, BMSC transplantation has the potential to improve RIHI via DNA repair and be a new therapeutic approach for patients with myocardial injury.

Radiosurgery Alters the Endothelial Surface Proteome: Externalized Intracellular Molecules as Potential Vascular Targets in Irradiated Brain Arteriovenous Malformations

Stereotactic radiosurgery (SRS) is an established treatment for brain arteriovenous malformations (AVMs) that drives blood vessel closure through cellular proliferation, thrombosis and fibrosis, but is limited by a delay to occlusion of 2-3 years and a maximum treatable size of 3 cm. In this current study we used SRS as a priming tool to elicit novel protein expression on the endothelium of irradiated AVM vessels, and these proteins were then targeted with prothrombotic conjugates to induce rapid thrombosis and vessel closure. SRS-induced protein changes on the endothelium in an animal model of AVM were examined using in vivo biotin labeling of surface-accessible proteins and comparative proteomics. LC-MS/MS using SWATH acquisition label-free mass spectrometry identified 280 proteins in biotin-enriched fractions. The abundance of 56 proteins increased after irradiation of the rat arteriovenous fistula (20 Gy, ≥1.5-fold). A large proportion of intracellular proteins were present in this subset: 29 mitochondrial and 9 cytoskeletal. Three of these proteins were chosen for further validation based on previously published evidence for surface localization and a role in autoimmune stimulation: cardiac troponin I (TNNI3); manganese superoxide dismutase (SOD2); and the E2 subunit of the pyruvate dehydrogenase complex (PDCE2). Immunostaining of AVM vessels confirmed an increase in abundance of PDCE2 across the vessel wall, but not a measurable increase in TNNI3 or SOD2. All three proteins co-localized with the endothelium after irradiation, however, more detailed subcellular distribution could not be accurately established. In vitro, radiation-stimulated surface translocation of all three proteins was confirmed in nonpermeabilized brain endothelial cells using immunocytochemistry. Total protein abundance increased modestly after irradiation for PDCE2 and SOD2 but decreased for TNNI3, suggesting that radiation primarily affects subcellular distribution rather than protein levels. The novel identification of these proteins as surface exposed in response to radiation raises important questions about their potential role in radiation-induced inflammation, fibrosis and autoimmunity, but may also provide unique candidates for vascular targeting in brain AVMs and other vascular tissues.

Ionizing radiation biomarkers in epidemiological studies - An update

Recent epidemiology studies highlighted the detrimental health effects of exposure to low dose and low dose rate ionizing radiation (IR): nuclear industry workers studies have shown increased leukaemia and solid tumour risks following cumulative doses of <100mSv and dose rates of <10mGy per year; paediatric patients studies have reported increased leukaemia and brain tumours risks after doses of 30-60mGy from computed tomography scans. Questions arise, however, about the impact of even lower doses and dose rates where classical epidemiological studies have limited power but where subsets within the large cohorts are expected to have an increased risk. Further progress requires integration of biomarkers or bioassays of individual exposure, effects and susceptibility to IR. The European DoReMi (Low Dose Research towards Multidisciplinary Integration) consortium previously reviewed biomarkers for potential use in IR epidemiological studies. Given the increased mechanistic understanding of responses to low dose radiation the current review provides an update covering technical advances and recent studies. A key issue identified is deciding which biomarkers to progress. A roadmap is provided for biomarker development from discovery to implementation and used to summarise the current status of proposed biomarkers for epidemiological studies. Most potential biomarkers remain at the discovery stage and for some there is sufficient evidence that further development is not warranted. One biomarker identified in the final stages of development and as a priority for further research is radiation specific mRNA transcript profiles.

Radiation-induced translational control of gene expression

Radiation-induced gene expression has long been hypothesized to protect against cell death. Defining this process would provide not only insight into the mechanisms mediating cell survival after radiation exposure, but also a novel source of targets for radiosensitization. However, whereas the radiation-induced gene expression profiles using total cellular mRNA have been generated for cell lines as well as normal tissues, with few exception, the changes in mRNA do not correlate with changes in the corresponding protein. The traditional approach to profiling gene expression, i.e., using total cellular RNA, does not take into account posttranscriptional regulation. In this review, we describe the use of gene expression profiling of polysome-bound RNA to establish that radiation modifies gene expression via translational control. Because changes in polysome-bound mRNA correlate with changes in protein, analysis of the translational profiles provides a unique data set for investigating the mechanisms mediating cellular radioresponse.

Cardiovascular diseases related to ionizing radiation: The risk of low-dose exposure (Review)

Traditionally, non-cancer diseases are not considered as health risks following exposure to low doses of ionizing radiation. Indeed, non-cancer diseases are classified as deterministic tissue reactions, which are characterized by a threshold dose. It is judged that below an absorbed dose of 100 mGy, no clinically relevant tissue damage occurs, forming the basis for the current radiation protection system concerning non-cancer effects. Recent epidemiological findings point, however, to an excess risk of non-cancer diseases following exposure to lower doses of ionizing radiation than was previously thought. The evidence is the most sound for cardiovascular disease (CVD) and cataract. Due to limited statistical power, the dose-risk relationship is undetermined below 0.5 Gy; however, if this relationship proves to be without a threshold, it may have considerable impact on current low-dose health risk estimates. In this review, we describe the CVD risk related to low doses of ionizing radiation, the clinical manifestation and the pathology of radiation-induced CVD, as well as the importance of the endothelium models in CVD research as a way forward to complement the epidemiological data with the underlying biological and molecular mechanisms.