Exposure to Low-Frequency Radiation Changes the Expression of Nestin, VEGF, BCRP and Apoptosis Markers During Glioma Treatment Strategy: An In Vitro Study.

BACKGROUND: Exposure to physical contamination during chemotherapy, including non-ionizing electromagnetic fields, raises concerns about the widespread sources of exposure to this type of radiation. Glioblastoma multiforme (GBM) is an aggressive central nervous system tumor that is hard to treat due to resistance to drugs such as temozolomide (TMZ). OBJECTIVE: Electromagnetic fields (EMF) and haloperidol (HLP) may have anticancer effects. In this study, we investigated the effects of TMZ, HLP, and EMF on GBM cell lines and analyzed the association between non-ionizing radiation and the risk of change in drug performance. METHODS: Cell viability and reactive oxygen species (ROS) generation were measured by MTT and NBT assay, respectively. Then, the expression levels of breast cancer-resistant protein (BCRP), Bax, Bcl2, Nestin, vascular endothelial growth factor (VEGF) genes, and P53, Bax, and Bcl2 Proteins were evaluated by real-time PCR and western blot. RESULTS: Co-treatment of GBM cells by HLP and TMZ enhanced apoptosis in T-98G and A172 cells by increasing the expression of P53 and Bax and decreasing Bcl-2. Interestingly, exposure of GBM cells to EMF decreased apoptosis in the TMZ+HLP group. CONCLUSION: In conclusion, EMF reduced the synergistic effect of TMZ and HLP. This hypothesis that patients who are treated for brain tumors and suffer from depression should not be exposed to EMF is proposed in the present study. There appears to be an urgent need to reconsider exposure limits for low-frequency magnetic fields, based on experimental and epidemiological research, the relationship between exposure to non-ionizing radiation and adverse human health effects.

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.

Cardiac Injury Following Chemo/Radiation Therapy: An Updated Review on Mechanisms and Therapeutic Approaches.

Cardiovascular disorders are among the critical side effects of cancer therapy. Damage to the function and normal structure of the heart can cause serious threats to patients that are being treated for cancer. Cardiovascular complications may be induced by various types of chemotherapy drugs and also radiation therapy. The severity of cardiovascular toxicity depends on several factors, such as types of drugs, tumor location for radiotherapy, the presence of cardiac disease history, the dose of drugs or ionizing radiation, etc. Radiotherapy and chemotherapy can cause heart diseases through various mechanisms, such as oxidative stress, inflammation, cell death, fibrosis, endothelial to mesenchymal transition (EndMT), etc. Chronic inflammation following damage to a huge number of cells can trigger more accumulation of inflammatory cells and chronic release of reactive oxygen species (ROS) and nitric oxide (NO). Oxidative stress can induce more cell death and cardiac remodeling through damage to vessels and valvular and disruption of the normal structure of the extracellular matrix. These changes may lead to cardiomyopathy, myocarditis, pericarditis, and vascular disorders that may lead to heart attack and death. This review provides basic information on cellular and molecular mechanisms of different types of cardiovascular disorders following cancer therapy by radiation or chemotherapy. We also recommend some adjuvants and targets to reduce the risk of heart toxicity by radiation/chemotherapy.

Comparative Study of Extremely Low-Frequency Electromagnetic Field, Radiation, and Temozolomide Administration in Spheroid and Monolayer Forms of the Glioblastoma Cell Line (T98).

BACKGROUND: Glioblastoma is the most common primary malignant tumor of the central nervous system. The patient's median survival rate is 13.5 months, so it is necessary to explore new therapeutic approaches. OBJECTIVE: Extremely low-frequency electromagnetic field (EMF) has been explored as a noninvasive cancer treatment. This study applied the EMF with previous conventional chemoradiotherapy for glioblastoma. METHODS: In this study, we evaluated the cytotoxic effects of EMF (50 Hz, 100 G), temozolomide (TMZ), and radiation (Rad) on gene expression of T98 glioma cell lines in monolayer and spheroid cell cultures. RESULTS: Treatment with Rad and EMF significantly increased apoptosis-related gene expression compared to the control group in monolayers and spheroids (p<0.001). The expression of apoptotic-related genes in monolayers was higher than the similar spheroid groups (p<0.001). We found that treatment with TMZ and EMF could increase the gene expression of the autophagy cascade markers compared to the control group (p<0.001). Autophagy-related gene expression in spheroids was higher than in the similar monolayer group (p<0.001). We demonstrated that coadministration of EMF, TMZ, and Rad significantly reduced cell cycle and drug resistance gene expression in monolayers and spheroids (p<0.001) compared to the control group. CONCLUSION: The combinational use of TMZ, Rad and, EMF showed the highest antitumor activity by inducing apoptosis and autophagy signaling pathways and inhibiting cell cycle and drug resistance gene expression. Furthermore, EMF increased TMZ or radiation efficiency.

Mitigation of Radiation-induced Pneumonitis and Lung Fibrosis using Alpha-lipoic Acid and Resveratrol.

BACKGROUND: Lung is a radiosensitive organ. Studies have shown that exposure of the lung to acute and high doses of radiation following inhalation of radioactive agents or an accidental radiological event may lead to pneumonitis and fibrosis, which are associated with a risk of death. So far, some agents have been studied for mitigation of pneumonitis and fibrosis following exposure of murine lung tissues to ionizing radiation. In this study, we aimed to detect the possible mitigatory effect of alpha-lipoic acid, resveratrol and their combination on mice pneumonitis and fibrosis markers following irradiation. METHODS: 25 mice were divided into 5 groups: control, radiation; radiation plus alpha-lipoic acid; radiation plus resveratrol; and radiation plus both resveratrol and alpha-lipoic acid. Mice chest regions were irradiated with 18 Gy using a cobalt-60 gamma rays source. Treatments started 24 h after irradiation and continued for two weeks. After 100 days, all mice were sacrificed and their lung tissues removed for histopathological evaluation. RESULTS: Pathological study showed that exposure to radiation led to severe pneumonitis and moderate fibrosis after 100 days. Both resveratrol and alpha-lipoic acid, as well as their combination could mitigate pneumonitis and fibrosis markers. Although, resveratrol could not mitigate infiltration of most inflammatory cells as well as inflammation and vascular damage, alpha-lipoic acid and its combination were able to mitigate most damaged markers. CONCLUSION: Alpha-lipoic acid and its combination with resveratrol were able to mitigate fibrosis and pneumonitis markers in mice lung tissues following lung irradiation. Although resveratrol has a protective effect on some markers, it has a weaker effect on lung injury. In conclusion, our results suggest that the combination of resveratrol and alpha-lipoic acid has a potent mitigatory effect compared to the single forms of these agents.

Protective Effect of Metformin, Resveratrol and Alpha-lipoic Acid on Radiation- Induced Pneumonitis and Fibrosis: A Histopathological Study.

BACKGROUND: Radiation-induced pneumonitis and fibrosis are the most common side effects of chest radiotherapy. They result from massive and chronic production of Reactive Oxygen Species (ROS), inhibition of antioxidant enzymes as well as the release of several inflammatory mediators. In this study, we aimed to detect the radioprotective effects of metformin (as inhibitor of mitochondrial ROS), resveratrol (as stimulator of antioxidant defense enzymes) and alpha-lipoic acid (as direct antioxidant) for alleviating radiation-induced pneumonitis and fibrosis. METHODS: 80 Male Mice were randomly allotted to eight groups which include G1: control; G2: resveratrol; G3: alpha-lipoic acid; G4: metformin; G5: radiation; G6: radiation plus resveratrol; G7: radiation plus alpha-lipoic acid; G8: radiation plus metformin. Drugs' doses were as follows: 100 mg/kg metformin, 200 mg/kg resveratrol and 200 mg/kg alpha-lipoic acid. Irradiation with a single radiation dose of 18 Gy was performed using a cobalt-60 (60Co) gamma-ray source. After 80 days, all mice were sacrificed and their lung tissues evaluated for morphological changes using histopathological markers. RESULTS: Irradiation led to acute pneumonitis including infiltration of inflammatory cells and damages to alveolar and vascular, as well as mild fibrosis. Metformin, alpha-lipoic acid and resveratrol were able to reduce pneumonitis and overcome radiation-induced fibrosis. CONCLUSION: All agents could protect against radiation-induced lung injury moderately. It is possible that administering higher doses of these drugs over a long period of time could give better radioprotection of the lung.

Mechanisms for Radioprotection by Melatonin; Can it be Used as a Radiation Countermeasure?

BACKGROUND: Melatonin is a natural body product that has shown potent antioxidant property against various toxic agents. For more than two decades, the abilities of melatonin as a potent radioprotector against toxic effects of ionizing radiation (IR) have been proved. However, in the recent years, several studies have been conducted to illustrate how melatonin protects normal cells against IR. Studies proposed that melatonin is able to directly neutralize free radicals produced by IR, leading to the production of some low toxic products. DISCUSSION: Moreover, melatonin affects several signaling pathways, such as inflammatory responses, antioxidant defense, DNA repair response enzymes, pro-oxidant enzymes etc. Animal studies have confirmed that melatonin is able to alleviate radiation-induced cell death via inhibiting pro-apoptosis and upregulation of anti-apoptosis genes. These properties are very interesting for clinical radiotherapy applications, as well as mitigation of radiation injury in a possible radiation disaster. An interesting property of melatonin is mitochondrial ROS targeting that has been proposed as a strategy for mitigating effects in radiosensitive organs, such as bone marrow, gastrointestinal system and lungs. However, there is a need to prove the mitigatory effects of melatonin in experimental studies. CONCLUSION: In this review, we aim to clarify the molecular mechanisms of radioprotective effects of melatonin, as well as possible applications as a radiation countermeasure in accidental exposure or nuclear/radiological disasters.

Radiation Protection and Mitigation by Natural Antioxidants and Flavonoids: Implications to Radiotherapy and Radiation Disasters.

BACKGROUND: Nowadays, ionizing radiations are used for various medical and terroristic aims. These purposes involve exposure to ionizing radiations. Hence, people are at risk for acute or late effects. Annually, millions of cancer patients undergo radiotherapy during their course of treatment. Also, some radiological or nuclear events in recent years pose a threat to people, hence the need for radiation mitigation strategies. Amifostine, the first FDA approved radioprotector, has shown some toxicities that limit its usage and efficiency. Due to these side effects, scientists have researched for other agents with less toxicity for better radioprotection and possible mitigation of the lethal effects of ionizing radiations after an accidental exposure. Flavonoids have shown promising results for radioprotection and can be administered in higher doses with less toxicity. Studies for mitigation of ionizing radiation-induced toxicities have concentrated on natural antioxidants. Detoxification of free radicals, management of inflammatory responses and attenuation of apoptosis signaling pathways in radiosensitive organs are the main mechanisms for radiation protection and mitigation with flavonoids and natural antioxidants. However, several studies have proposed that a combination in the form of some antioxidants may alleviate radiation toxicities more effectively in comparison to a single form of antioxidants. CONCLUSION: In this review, we focus on recent findings about natural radioprotectors and mitigators which are clinically applicable for radiotherapy patients, as well as injured people in possible radiation accidents.

Radiation-induced inflammation and autoimmune diseases.

Currently, ionizing radiation (IR) plays a key role in the agricultural and medical industry, while accidental exposure resulting from leakage of radioactive sources or radiological terrorism is a serious concern. Exposure to IR has various detrimental effects on normal tissues. Although an increased risk of carcinogenesis is the best-known long-term consequence of IR, evidence has shown that other diseases, particularly diseases related to inflammation, are common disorders among irradiated people. Autoimmune disorders are among the various types of immune diseases that have been investigated among exposed people. Thyroid diseases and diabetes are two autoimmune diseases potentially induced by IR. However, the precise mechanisms of IR-induced thyroid diseases and diabetes remain to be elucidated, and several studies have shown that chronic increased levels of inflammatory cytokines after exposure play a pivotal role. Thus, cytokines, including interleukin-1(IL-1), tumor necrosis factor (TNF-α) and interferon gamma (IFN-γ), play a key role in chronic oxidative damage following exposure to IR. Additionally, these cytokines change the secretion of insulin and thyroid-stimulating hormone(TSH). It is likely that the management of inflammation and oxidative damage is one of the best strategies for the amelioration of these diseases after a radiological or nuclear disaster. In the present study, we reviewed the evidence of radiation-induced diabetes and thyroid diseases, as well as the potential roles of inflammatory responses. In addition, we proposed that the mitigation of inflammatory and oxidative damage markers after exposure to IR may reduce the incidence of these diseases among individuals exposed to radiation.

COX-2 in Radiotherapy: A Potential Target for Radioprotection and Radiosensitization.

BACKGROUND: Each year, millions of people die from cancer. Radiotherapy is one of the main treatment strategies for cancer patients. Despite the beneficial roles of treatment with radiation, several side effects may threaten normal tissues of patients in the years after treatment. DISCUSSION: Moreover, high incidences of second primary cancers may reduce therapeutic ratio of radiotherapy. The search for appropriate targets of radiosensitization of tumor cells as well as radioprotection of normal tissues is one of the most interesting aims in radiobiology. Cyclooxygenase-2 (COX-2), as an inflammatory mediator has attracted interests for both aims. COX-2 activity is associated with ROS production and inflammatory signs in normal tissues. These effects further amplify radiation toxicity in irradiated cells as well as adjacent cells through a phenomenon known as Bystander effect. Increased COX-2 expression in distant non-irradiated tissues causes oxidative DNA damage and elevated cancer risk. Moreover, in tumors, the activation of this enzyme can increase resistance of malignant cells to radiotherapy. Hence, the inhibition of COX-2 has been proposed for better therapeutic response and amelioration of normal tissues. Celecoxib is one of the most studied COX-2 inhibitor for radiosensitization and radioprotection, while some other inhibitors have shown interesting results. CONCLUSION: In this review, we describe the role of COX-2 in radiation normal tissue injury as well as irradiated bystander and non-targeted cells. In addition, mechanisms of COX-2 induced tumor resistance to radiotherapy and the potential role of COX-2 inhibition are discussed.

Stem Cell Tracing Through MR Molecular Imaging.

Stem cell therapy opens a new window in medicine to overcome several diseases that remain incurable. It appears such diseases as cardiovascular disorders, brain injury, multiple sclerosis, urinary system diseases, cartilage lesions and diabetes are curable with stem cell transplantation. However, some questions related to stem cell therapy have remained unanswered. Stem cell imaging allows approval of appropriated strategies such as selection of the type and dose of stem cell, and also mode of cell delivery before being tested in clinical trials. MRI as a non-invasive imaging modality provides proper conditions for this aim. So far, different contrast agents such as superparamagnetic or paramagnetic nanoparticles, ultrasmall superparamagnetic nanoparticles, fluorine, gadolinium and some types of reporter genes have been used for imaging of stem cells. The core subject of these studies is to investigate the survival and differentiation of stem cells, contrast agent's toxicity and long term following of transplanted cells. The promising results of in vivo and some clinical trial studies may raise hope for clinical stem cells imaging with MRI.

Metformin Protects Against Radiation-Induced Pneumonitis and Fibrosis and Attenuates Upregulation of Dual Oxidase Genes Expression.

Purpose: Lung tissue is one of the most sensitive organs to ionizing radiation (IR). Early and late side effects of exposure to IR can limit the radiation doses delivered to tumors that are within or adjacent to this organ. Pneumonitis and fibrosis are the main side effects of radiotherapy for this organ. IL-4 and IL-13 have a key role in the development of pneumonitis and fibrosis. Metformin is a potent anti-fibrosis and redox modulatory agent that has shown radioprotective effects. In this study, we aimed to evaluate possible upregulation of these cytokines and subsequent cascades such as IL4-R1, IL-13R1, Dual oxidase 1 (DUOX1) and DUOX2. In addition, we examined the potential protective effect of metformin in these cytokines and genes, as well as histopathological changes in rat's lung tissues. Methods: 20 rats were divided into 4 groups: control; metformin treated; radiation + metformin; and radiation. Irradiation was performed with a 60Co source delivering 15 Gray (Gy) to the chest area. After 10 weeks, rats were sacrificed and their lung tissues were removed for histopathological, real-time PCR and ELISA assays. Results: Irradiation of lung was associated with an increase in IL-4 cytokine level, as well as the expression of IL-4 receptor-a1 (IL4ra1) and DUOX2 genes. However, there was no change in the level of IL-13 and its downstream gene including IL-13 receptor-a2 (IL13ra2). Moreover, histopathological evaluations showed significant infiltration of lymphocytes and macrophages, fibrosis, as well as vascular and alveolar damages. Treatment with metformin caused suppression of upregulated genes and IL-4 cytokine level, associated with amelioration of pathological changes. Conclusion: Results of this study showed remarkable pathological damages, an increase in the levels of IL-4, IL4Ra1 and Duox2, while that of IL-13 decreased. Treatment with metformin showed ability to attenuate upregulation of IL-4-DUOX2 pathway and other pathological damages to the lung after exposure to a high dose of IR.

Metformin Protects Against Radiation-Induced Heart Injury and Attenuates the Upregulation of Dual Oxidase Genes Following Rat's Chest Irradiation.

Radiation-induced heart toxicity is one of the serious side effects after a radiation disaster or radiotherapy for patients with chest cancers, leading to a reduction in the quality of life of the patients. Evidence has shown that infiltration of inflammatory cells plays a key role in the development of functional damages to the heart via chronic upregulation of some pro-fibrotic and pro-inflammatory cytokines. These changes are associated with continuous free radical production and increased stiffness of heart muscle. IL-4 and IL-13 are two important pro-fibrotic cytokines which contribute to the side effects of ionizing radiation exposure. Recent studies have proposed that IL-4 through upregulation of DUOX2, and IL-13 via stimulation of DUOX1 gene expression, are involved in the development of radiation late effects. In the present study, we aimed to detect changes in the expression of these pathways following irradiation of rat's heart. Furthermore, we evaluated the possible protective effect of metformin on the development of these abnormal changes. 20 male rats were divided into 4 groups (control, radiation, metformin treated, metformin + radiation). These rats were irradiated with 15 Gy 60Co gamma rays, and sacrificed after 10 weeks for evaluation of the changes in the expression of IL4R1, IL-13R2a, DUOX1 and DUOX2. In addition, the levels of IL-4 and IL-13 cytokines, as well as infiltration of macrophages and lymphocytes were detected. Results showed an upregulation of both DUOX1 and DUOX2 pathways in the presence of metformin, while the level of IL-13 did not show any significant change. This was associated with infiltration of macrophages and lymphocytes. Also, treatment with metformin could significantly attenuate accumulation of inflammatory cells, and upregulate these pathways. Therefore, suppression of dual oxidase genes by metformin may be a contributory factor to its protective effect.

Mechanisms of Radiation Bystander and Non-Targeted Effects: Implications to Radiation Carcinogenesis and Radiotherapy.

BACKGROUND: Knowledge of radiobiology is of paramount importance to be able to grasp and have an in-depth understanding of the consequences of ionizing radiation. One of the most important effects of this physical stressor's interaction to targeted and non-targeted cells, tissues and organs is on the late effects on the development of primary and secondary cancers. Thus, an in-depth understanding of the mechanisms of radiation carcinogenesis remains to be elucidated, and some studies have demonstrated or proposed a role of non-targeted effect in excess risk of cancer incidence. The non-targeted effect in radiobiology refers to a dynamic complex response in non-irradiated tissues caused by the release of presumably of clastogenic factors from irradiated cells. Although, most of these responses in non-targeted tissues have marked similarities to irradiated tissues, other studies have shown some differences. Also, the non-targeted effect has shown sex and tissue specificity that are seen in irradiated tissues too. So far, several studies have been conducted to depict mechanisms that may be involved in this phenomenon. Epigenetic dysfunctions, DNA damage and cell death are responsible for initiation of several signaling pathways that finally result in secretion of clastogenic factors. Moreover, studies have shown that damage to both nucleus and mitochondrial DNA, membrane and some organelles is involved. Oxidized DNA associated with other cell death factors stimulates secretion of inflammatory as well as some anti-inflammatory cytokines from irradiated area. Additionally, oxidative stress that results in damage to cellular structures to include cell membranes can affect secretion of exosomes and miRNAs. These bystander effect exogenous mediators migrate to distant tissues and stimulate various signaling pathways which can lead to changes in immune responses, epigenetic modulations and radiation carcinogenesis. CONCLUSION: In this review, we focus on descriptive and hierarchical events with emphasis on the molecular and functional interactions of ionizing radiation with cells to the mechanisms involved in cancer induction in non-targeted tissues.

Targeting of Inflammation for Radiation Protection and Mitigation.

BACKGROUND: Inflammation is the response of the immune system that guards the body against several harmful stimuli in normal conditions. However, in response to ionizing radiation that leads to a massive cell death and DNA aberrations, this phenomenon causes various side effects in normal tissues. Inflammation is involved in various side effects such as gastrointestinal toxicity, mucositis, skin reactions, nervous system damage, pneumonitis, fibrosis and so on. DISCUSSION: Observations have proposed that inflammatory mediators are involved in the toxic effect of ionizing radiation on non-irradiated cells via a phenomenon named bystander effect. Inflammation in both irradiated and non-irradiated cells can trigger genomic instability, leading to increased risk of carcinogenesis. Targeting the inflammatory mediators has been an interesting idea for improving the therapeutic ratio throughout the reduction of normal tissue injury as well as an increase in tumor response to radiotherapy. CONCLUSION: So far, various targets have been proposed for the amelioration of radiation toxicity in radiotherapy. Of different targets, NF-κB, COX-2, some of NADPH Oxidase subfamilies, TGF-ß, p38 and the renin-angiotensin system have shown promising results. Interestingly, inhibition of these targets can help sensitize the tumor cells to the radiation treatment with some mechanisms such as suppression of angiogenesis and tumor growth as well as induction of apoptosis. In this review, we focus on recent advances on promising studies for targeting the inflammatory mediators in radiotherapy.