Induction of Cancer Cell Death by Apigenin: A Review on Different Cell Death Pathways.

Induction of cell death and inhibition of cell proliferation in cancer have been set as some of the main goals in anti-tumor therapy. Cancer cell resistance leads to less efficient cancer therapy, and consequently, to higher doses of anticancer drugs, which may eventually increase the risk of serious side effects in normal tissues. Apigenin, a nature-derived and herbal agent, which has shown anticancer properties in several types of cancer, can induce cell death directly and/or amplify the induction of cell death through other anti-tumor modalities. Although the main mechanism of apigenin in order to induce cell death is apoptosis, other cell death pathways, such as autophagic cell death, senescence, anoikis, necroptosis, and ferroptosis, have been reported to be induced by apigenin. It seems that apigenin enhances apoptosis by inducing anticancer immunity and tumor suppressor genes, like p53 and PTEN, and also by inhibiting STAT3 and NF-κB signaling pathways. Furthermore, it may induce autophagic cell death and ferroptosis by inducing endogenous ROS generation. Stimulation of ROS production and tumor suppressor genes, as well as downregulation of drug-resistance mediators, may induce other mechanisms of cell death, such as senescence, anoikis, and necroptosis. It seems that the induction of each type of cell death is highly dependent on the type of cancer. These modulatory actions of apigenin have been shown to enhance anticancer effects by other agents, such as ionizing radiation and chemotherapy drugs. This review explains how cancer cell death may be induced by apigenin at the cellular and molecular levels.

Resveratrol in Cancer Therapy: From Stimulation of Genomic Stability to Adjuvant Cancer Therapy: A Comprehensive Review.

Cancer therapy through anticancer drugs and radiotherapy is associated with several side effects as well as tumor resistance to therapy. The genotoxic effects of chemotherapy and radiotherapy may lead to genomic instability and increased risk of second cancers. Furthermore, some responses in the tumor may induce the exhaustion of antitumor immunity and increase the resistance of cancer cells to therapy. Administration of low-toxicity adjuvants to protect normal tissues and improve therapy efficacy is an intriguing strategy. Several studies have focused on natural-derived agents for improving the antitumor efficiency of radiotherapy, chemotherapy, and novel anticancer drugs such as immunotherapy and targeted cancer therapy. Resveratrol is a naturally occurring substance with intriguing antioxidant, cardioprotective, anti-diabetes, and antitumor properties. Resveratrol has been demonstrated to modulate tumor resistance and mitigate normal tissue toxicity following exposure to various drugs and ionizing radiation. Compelling data suggest that resveratrol may be an appealing adjuvant in combination with various anticancer modalities. Although the natural form of resveratrol has some limitations, such as low absorption in the intestine and low bioavailability, several experiments have demonstrated that using certain carriers, such as nanoparticles, can increase the therapeutic efficacy of resveratrol in preclinical studies. This review highlights various effects of resveratrol that may be useful for cancer therapy. Consequently, we describe how resveratrol can protect normal tissue from genomic instability. In addition, the various mechanisms by which resveratrol exerts its antitumor effects are addressed. Moreover, the outcomes of combination therapy with resveratrol and other anticancer agents are reviewed.

Imperatorin Attenuates the Proliferation of MCF-7 Cells in Combination with Radiotherapy or Hyperthermia.

BACKGROUND: Breast cancer is one of the most common types of malignancies in the world. Cancer resistance is an unavoidable consequence of therapy with radiation or other modalities. Ongoing research aims to improve cancer response to therapy. AIM: The aim of this study was to evaluate the possible sensitization effect of imperatorin (IMP) in combination with external radiotherapy (ERT) or HT. METHODS: After treatment of MCF-7 breast cancer cells with IMP, cells were exposed to 4 Gy X-rays or HT (42 °C for 1 hour). The viability of MCF-7 cells was measured using an MTT assay. Furthermore, the expression of pro-apoptotic genes, including Bax, Bcl-2, caspase-3, caspase-8, and caspase- 9, was investigated using real-time PCR. The sensitizing effect of IMP in combination with ERT or HT was calculated and compared to ERT or HT alone. RESULTS: Results showed an increase in the expression of pro-apoptotic genes and downregulation of anti-apoptotic Bcl-2 following ERT and HT. Furthermore, cell viability was reduced following these treatments. IMP was able to augment these effects of ERT and HT. CONCLUSION: IMP could increase the efficiency of HT and ERT. This effect of IMP may suggest it as an adjuvant for increasing the therapeutic efficiency of ERT.

Modulation of Radiation-Induced NADPH Oxidases in Rat's Heart Tissues by Melatonin.

BACKGROUND: Experimental studies have shown that infiltration of inflammatory cells as well as upregulation of some cytokines play a central role in the development of late effects of ionizing radiation in heart tissues. Evidences have shown that an increased level of TGF-ß has a direct correlation with late effects of exposure to ionizing radiation such as chronic oxidative stress and fibrosis. Recent studies have shown that TGF-ß, through upregulation of pro-oxidant enzymes such as NOX2 and NOX4, promotes continuous ROS production and accumulation of fibrosis. OBJECTIVE: In present study, we aimed to evaluate the expression of NOX2 and NOX4 signaling pathways as well as possible modulatory effects of melatonin on the expression of these genes. MATERIAL AND METHODS: In this experimental study, four groups of 20 rats (5 in each) were used as follows; G1: control; G2: melatonin; G3: radiation; G4: radiation + melatonin. 100 mg/kg of melatonin was administrated before irradiation of heart tissues with 15 Gy gamma rays. 10 weeks after irradiation, heart tissues were collected for real-time Polymerase chain reaction (PCR). RESULTS: Results showed a significant increase in the expression of TGF-ß, Smad2, NF-kB, NOX2 and NOX4. The upregulation of NOX2 was more obvious by 20-fold compared to other genes. Except for TGF-ß, melatonin could attenuate the expression of other genes. CONCLUSION: This study indicated that exposure of rat's heart tissues to radiation leads to upregulation of TGF-ß-NOX4 and TGF-ß-NOX2 pathways. Melatonin, through modulation of these genes, may be able to alleviate radiation-induced chronic oxidative stress and subsequent consequences.

Suberosin Attenuates the Proliferation of MCF-7 Breast Cancer Cells in Combination with Radiotherapy or Hyperthermia.

AIM: The aim of this study was to determine the proliferation of MCF-7 following irradiation or hyperthermia as alone or pre-treatment with suberosin. BACKGROUND: Radiotherapy is a major therapeutic modality for the control of breast cancer. However, hyperthermia can be prescribed for relief of pain or enhancing cancer cell death. Some studies have attempted its use as an adjuvant to improve therapeutic efficiency. Suberosin is a cumarin- derived natural agent that has shown anti-inflammatory properties. OBJECTIVE: In this in vitro study, possible sensitization effect of suberosin in combination with radiation or hyperthermia was evaluated. METHODS: MCF-7 breast cancer cells were irradiated or received hyperthermia with or without treatment with suberosin. The incidence of apoptosis as well as viability of MCF-7 cells were observed. Furthermore, the expressions of pro-apoptotic genes such as Bax, Bcl-2, and some caspases were evaluated using real-time PCR. RESULTS: Both radiotherapy or hyperthermia reduced the proliferation of MCF-7 cells. Suberosin amplified the effects of radiotherapy or hyperthermia for induction of pro-apoptotic genes and reducing cell viability. CONCLUSION: Suberosin has a potent anti-cancer effect when combined with radiotherapy or hyperthermia. It could be a potential candidate for killing breast cancer cells as well as increasing the therapeutic efficiency of radiotherapy or hyperthermia.

Resveratrol Induces Apoptosis and Attenuates Proliferation of MCF-7 Cells in Combination with Radiation and Hyperthermia.

AIM: In the current in vitro study, we tried to examine the possible role of resveratrol as a sensitizer in combination with radiotherapy or hyperthermia. BACKGROUND: Breast cancer is the most common malignancy for women and one of the most common worldwide. It has been suggested that using non-invasive radiotherapy alone cannot eliminate cancer cells. Hyperthermia, which is an adjuvant modality, induces cancer cell death mainly through apoptosis and necrosis. However, cancer cells can also develop resistance to this modality. OBJECTIVE: The objective of this study was to determine possible potentiation of apoptosis when MCF-7 cells treated with resveratrol before hyperthermia or radiotherapy. METHODS: MCF-7 cancer cells were treated with different doses of resveratrol to achieve IC50%. Afterwards, cells treated with the achieved concentration of resveratrol were exposed to radiation or hyperthermia. Proliferation, apoptosis and the expression of pro-apoptotic genes were evaluated using flow cytometry, MTT assay and real-time PCR. Results for each combination therapy were compared to radiotherapy or hyperthermia without resveratrol. RESULTS: Both irradiation or hyperthermia could reduce the viability of MCF-7 cells. Furthermore, the regulation of Bax and caspase genes increased, while Bcl-2 gene expression reduced. Resveratrol potentiated the effects of radiation and hyperthermia on MCF-7 cells. CONCLUSION: Results of this study suggest that resveratrol is able to induce the regulation of pro-apoptotic genes and attenuate the viability of MCF-7 cells. This may indicate the sensitizing effect of resveratrol in combination with both radiotherapy and hyperthermia.

Mitigation of radiation-induced hematopoietic system injury by melatonin.

BACKGROUND: Increased risks of exposure to accidental radiation events are a concern in today's world. Radiation terror, nuclear explosion, as well as accidental exposure to radioactive sources in some industries pose a threat to the life of exposed persons. Studies have been conducted using some low-toxic agents to mitigate radiation toxicity and increase survival probability for exposed people. In the current study, we aimed to show the mitigation of radiation-induced mortality and bone marrow toxicity using postirradiation treatment with melatonin. METHOD: Mice whole bodies were exposed to 4 or 7 Gy radiation followed by treatment with melatonin after 24 hours. Survival of mice with or without melatonin, the levels of peripheral cells, transforming growth factor (TGF)-ß and 8-hydroxy-2' -deoxyguanosine (8-OHdG) in the bone marrow, as well as the expression of NADPH oxidase (NOX)2 and NOX4 in bone marrow cells were evaluated. RESULTS: Whole body irradiation led to mortality 30 days after irradiation. However, melatonin treatment reduced mortality. Irradiation also showed severe reduction of lymphocytes, platelets, and red blood cells. The expressions of NOX2 and NOX4, in addition to TGF-ß level, were increased after exposure to radiation. Melatonin ameliorated the increased levels of these factors and improved the number of blood cells. CONCLUSIONS: Melatonin showed ability to mitigate radiation-induced hematopoietic system toxicity and also increased survival rate. These results suggest that melatonin could be a potential mitigator for accidental radiation events.

Targets for protection and mitigation of radiation injury.

Protection of normal tissues against toxic effects of ionizing radiation is a critical issue in clinical and environmental radiobiology. Investigations in recent decades have suggested potential targets that are involved in the protection against radiation-induced damages to normal tissues and can be proposed for mitigation of radiation injury. Emerging evidences have been shown to be in contrast to an old dogma in radiation biology; a major amount of reactive oxygen species (ROS) production and cell toxicity occur during some hours to years after exposure to ionizing radiation. This can be attributed to upregulation of inflammatory and fibrosis mediators, epigenetic changes and disruption of the normal metabolism of oxygen. In the current review, we explain the cellular and molecular changes following exposure of normal tissues to ionizing radiation. Furthermore, we review potential targets that can be proposed for protection and mitigation of radiation toxicity.

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.

Protection from Radiation-induced Damage in Rat's Ileum and Colon by Combined Regimens of Melatonin and Metformin: A Histopathological Study.

BACKGROUND: Radiation-induced enteritis and proctitis are common side effects of abdominopelvic cancers among patients that undergo radiotherapy for prostate, colorectal or urinary cancers. Exposure of these tissues to high doses of radiation leads to damage to villous, inflammation, pain, ulcer and bleeding, which may cause malabsorption and gastrointestinal disorders. To date, several procedures such as pharmaceutical treatment have been proposed for protection and mitigation of gastrointestinal toxicity following radiotherapy. AIMS: In the current study, we aimed to investigate the possible radioprotection of ileum and colon in rats using a combination of melatonin and metformin. METHODS: In this experimental study, 30 male Wistar rats were randomly assigned to six groups: control, melatonin (100 mg/kg) treatment, melatonin (100 mg/kg) plus metformin (100 mg/kg) treatment, radiation (10 Gy to whole body) group, radiation + melatonin (100 mg/kg) treatment, and radiation + melatonin (100 mg/kg) plus metformin (100 mg/kg) treatment. After 3.5 days, rats were sacrificed and their ileum and colon tissues carefully removed. Histopathological evaluations were conducted on these tissue samples. RESULTS: Histological evaluations reported moderate to severe damages to ileum and colon following whole body irradiation. Melatonin administration was able to protect the ileum remarkably, while the combination of melatonin and metformin was less effective. Interestingly, for the colon, melatonin was less effective while its combination with metformin was able to protect against radiation toxicity completely. CONCLUSION: For the ileum, melatonin was a more effective radioprotector compared to its combination with metformin. However, the combination of melatonin and metformin can be proposed as an ideal radioprotector for the colon.

Mitigation of Radiation-induced Gastrointestinal System Injury using Resveratrol or Alpha-lipoic Acid: A Pilot Histopathological Study.

AIM: In this study, we aimed to determine possible mitigation of radiationinduced toxicities in the duodenum, jejunum and colon using post-exposure treatment with resveratrol and alpha-lipoic acid. BACKGROUND: After the bone marrow, gastrointestinal system toxicity is the second critical cause of death following whole-body exposure to radiation. Its side effects reduce the quality of life of patients who have undergone radiotherapy. Resveratrol has an antioxidant effect and stimulates DNA damage responses (DDRs). Alpha-lipoic acid neutralizes free radicals via the recycling of ascorbic acid and alpha-tocopherol. OBJECTIVE: This study is a pilot investigation of the mitigation of enteritis using resveratrol and alpha-lipoic acid following histopathological study. METHODS: 60 male mice were randomly assigned to six groups; control, resveratrol treatment, alpha-lipoic acid treatment, whole-body irradiation, irradiation plus resveratrol, and irradiation plus alpha-lipoic acid. The mice were irradiated with a single dose of 7 Gy from a cobalt-60 gamma-ray source. Treatment with resveratrol or alpha-lipoic acid started 24 h after irradiation and continued for 4 weeks. All mice were sacrificed after 30 days for histopathological evaluation of radiation-induced toxicities in the duodenum, jejunum and colon. RESULTS AND DISCUSSION: Exposure to radiation caused mild to severe damages to vessels, goblet cells and villous. It also led to significant infiltration of macrophages and leukocytes, especially in the colon. Both resveratrol and alpha-lipoic acid were able to mitigate morphological changes. However, they could not mitigate vascular injury. CONCLUSION: Resveratrol and alpha-lipoic acid could mitigate radiation-induced injuries in the small and large intestine. A comparison between these agents showed that resveratrol may be a more effective mitigator compared to alpha-lipoic acid.

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.

The Radioprotective Effect of Combination of Melatonin and Metformin on Rat Duodenum Damage Induced by Ionizing Radiation: A Histological Study.

BACKGROUND: Radiation toxicity is one of the major concerns for patients with gastrointestinal cancers that undergo radiotherapy. Duodenum is one of the most radiosensitive parts of gastrointestinal system that may be exposed to a high dose of radiation during radiotherapy for some cancers. The development or identification of appropriate radioprotectors with less toxicity is an interesting aim in radiobiology for clinical radiotherapy applications. In the present study, we aimed to evaluate the radioprotective effect of melatonin and metformin combination in rat's duodenum. In addition, we compared our results with the radioprotective effect of melatonin, when administered alone. MATERIALS AND METHODS: Thirty male rats were divided into six groups: control, melatonin treatment, melatonin plus metformin treatment, whole-body irradiation, irradiation with melatonin treatment, and irradiation with melatonin plus metformin treatment. Irradiation was performed with 10 Gy cobalt-60 gamma rays, while 100 mg/kg of melatonin and metformin were administered 24 h before to 72 h after irradiation. After 3.5 days, their duodenum tissues were removed for histopathological evaluation. RESULTS: Irradiation of rats led to mild-to-moderate mucositis signs, infiltration of inflammatory cells, necrosis, and damage to Brunner's glands and reduction of goblet cells. Melatonin was able to alleviate these damages, while melatonin plus metformin could reduce some radiation toxicity signs. CONCLUSION: Administration of melatonin plus metformin could reduce mucositis in duodenum. However, the administration of melatonin is more effective for mitigation of duodenal injury compared with melatonin plus metformin.

Mitigation of Radiation-Induced Lung Pneumonitis and Fibrosis Using Metformin and Melatonin: A Histopathological Study.

Background and objectives: Pneumonitis and fibrosis are the most common consequences of lung exposure to a high dose of ionizing radiation during an accidental radiological or nuclear event, and may lead to death, after some months to years. So far, some anti-inflammatory and antioxidant agents have been used for mitigation of lung injury. In the present study, we aimed to detect possible mitigatory effects of melatonin and metformin on radiation-induced pneumonitis and lung fibrosis. Materials and methods: 40 male mice were divided into 4 groups (10 mice in each). For control group, mice did not receive radiation or drugs. In group 2, mice were irradiated to chest area with 18 Gy gamma rays. In groups 3 and 4, mice were first irradiated similar to group 2. After 24 h, treatment with melatonin as well as metformin began. Mice were sacrificed after 100 days for determination of mitigation of lung pneumonitis and fibrosis by melatonin or metformin. Results: Results showed that both melatonin and metformin are able to mitigate pneumonitis and fibrosis markers such as infiltration of inflammatory cells, edema, vascular and alveolar thickening, as well as collagen deposition. Conclusion: Melatonin and metformin may have some interesting properties for mitigation of radiation pneumonitis and fibrosis after an accidental radiation event.

Selenium-L-methionine modulates radiation injury and Duox1 and Duox2 upregulation in rat's heart tissues.

Introduction: Redox interactions play a key role in radiation injury including heart diseases. In present study, we aimed to detect the possible protective role of selenium-L-methionine on infiltration of immune cells and Duox1&2 upregulation in rat's heart tissues. Methods: In this study, 20 rats were divided into 4 groups (5 rats in each) namely: irradiation; irradiation plus Selenium-L-methionine; control; and Selenium-L-methionine treatment. Irradiation (15 Gy to chest) was performed using a cobalt-60 gamma ray source while 4 mg/kg of selenium-L-methionine was administered intraperitoneally. Ten weeks after irradiation, rats were sacrificed for detection of IL-4 and IL-13 cytokines, infiltration of macrophages and lymphocytes as well as the expressions of IL4Ra1, Duox1, IL13Ra2 and Duox2. Results: Results showed an increase in the level of IL-4 as well as the expressions of IL4Ra1, Duox1 and Duox2. Similarly, there was an increase in the infiltration of lymphocytes and macrophages. There was significant attenuation of all these changes following treatment with selenium-L-methionine. Conclusion: Selenium-L-methionine has the potential to protect heart tissues against radiation injury. Downregulation of pro-oxidant genes and modulation of some cytokines such as IL-4 are involved in the radioprotective effect of selenium-L-methionine on heart tissues.

Radiation-Induced Dual Oxidase Upregulation in Rat Heart Tissues: Protective Effect of Melatonin.

Background: Radiation-induced heart injury can lead to increased risk of heart failure, attack, and ischemia. Some studies proposed IL-4 and IL-13 as two important cytokines that are involved in late effects of ionizing radiation. On the other hand, these cytokines may, through upregulation of Duox1 and Duox2, induce chronic oxidative stress, inflammation, and fibrosis. In this study, we evaluated the upregulation of Duox1 and Duox2 pathways in hearts following chest irradiation in rats and then detected possible attenuation of them by melatonin. Materials and Methods: Twenty male Wistar rats were divided into four groups: (1) control; (2) melatonin treated (100 mg/kg); (3) radiation (15 Gy gamma rays); (4) melatonin treated before irradiation. All rats were sacrificed after 10 weeks and their heart tissues collected for real-time PCR (RT-PCR), ELISA detection of IL-4 and IL-13, as well as histopathological evaluation of macrophages and lymphocytes infiltration. Results: Results showed an upregulation of IL-4, IL4ra1, Duox1, and Duox2. The biggest changes were for IL4ra1 and Duox1. Treatment with melatonin before irradiation could attenuate the upregulation of all genes. Melatonin also caused a reduction in IL-4 as well as reverse infiltration of inflammatory cells. Conclusion: Duox1 and Duox2 may be involved in the late effects of radiation-induced heart injury. Also, via attenuation of these genes, melatonin can offer protection against the toxic effects of radiation on the heart.

Melatonin Attenuates Upregulation of Duox1 and Duox2 and Protects against Lung Injury following Chest Irradiation in Rats.

OBJECTIVE: The Lung is one of the most radiosensitive organs of the body. The infiltration of macrophages and lymphocytes into the lung is mediated via the stimulation of T-helper 2 cytokines such as IL-4 and IL-13, which play a key role in the development of fibrosis. It is likely that these cytokines induce chronic oxidative damage and inflammation through the upregulation of Duox1 and Duox2, which can increase the risk of late effects of ionizing radiation (IR) such as fibrosis and carcinogenesis. In the present study, we aimed to evaluate the possible increase of IL-4 and IL-13 levels, as well as their downstream genes such as IL4ra1, IL13ra2, Duox1, and Duox2. MATERIALS AND METHODS: In this experimental animal study, male rats were divided into 4 groups: i. Control, ii. Melatonintreated, iii. Radiation, and iv. Melatonin (100 mg/kg) plus radiation. Rats were irradiated with 15 Gy 60Co gamma rays and then sacrificed after 67 days. The expressions of IL4ra1, IL13ra2, Duox1, and Duox2, as well as the levels of IL-4 and IL-13, were evaluated. The histopathological changes such as the infiltration of inflammatory cells, edema, and fibrosis were also examined. Moreover, the protective effect of melatonin on these parameters was also determined. RESULTS: Results showed a 1.5-fold increase in the level of IL-4, a 5-fold increase in the expression of IL4ra1, and a 3-fold increase in the expressions of Duox1 and Duox2. However, results showed no change for IL-13 and no detectable expression of IL13ra2. This was associated with increased infiltration of macrophages, lymphocytes, and mast cells. Melatonin treatment before irradiation completely reversed these changes. CONCLUSION: This study has shown the upregulation of IL-4-IL4ra1-Duox2 signaling pathway following lung irradiation. It is possible that melatonin protects against IR-induced lung injury via the downregulation of this pathway and attenuation of inflammatory cells infiltration.

Melatonin Modulates Regulation of NOX2 and NOX4 Following Irradiation in the Lung.

BACKGROUND: Exposure to ionizing radiation may lead to chronic upregulation of inflammatory mediators and pro-oxidant enzymes, which give rise to continuous production of reactive oxygen species (ROS). NADPH oxidases are among the most important ROS producing enzymes. Their upregulation is associated with DNA damage and genomic instability. In the present study, we sought to determine the expressions of NADPH oxidases; NOX2 and NOX4, in rat's lung following whole body or pelvis irradiation. In addition, we evaluated the protective effect of melatonin on the expressions of NOX2 and NOX4, as well as oxidative DNA injury. METHODS: 35 male rats were divided into 7 groups, G1: control; G2: melatonin (100 mg/kg) treatment; G3: whole body irradiation (2 Gy); G4: melatonin plus whole body irradiation; G5: local irradiation to pelvis area; G6: melatonin treatment plus 2 Gy gamma rays to pelvis area; G7: scatter group. All the rats were sacrificed after 24 h. afterwards, the expressions of TGFßR1, Smad2, NF- κB, NOX2 and NOX4 were detected using real-time PCR. Also, the level of 8-OHdG was detected by ELISA, and NOX2 and NOX4 protein levels were detected by western blot. RESULTS: Whole body irradiation led to the upregulation of all genes, while local pelvis irradiation caused upregulation of TGFßR1, NF-κB, NOX2 and NOX4, as well as protein levels of NOX2 and NOX4. Treatment with melatonin reduced the expressions of these genes and also alleviated oxidative injury in both targeted and non-targeted lung tissues. Results also showed no significant reduction for NOX2 and NOX4 in bystander tissues following melatonin treatment. CONCLUSION: It is possible that upregulation of NOX2 and NOX4 is involved in radiation-induced targeted and non-targeted lung injury. Melatonin may reduce oxidative stress following upregulation of these enzymes in directly irradiated lung tissues but not for bystander.

Evaluating the protective effect of resveratrol, Q10, and alpha-lipoic acid on radiation-induced mice spermatogenesis injury: A histopathological study.

BACKGROUND: Testis is one of the most sensitive organs against the toxic effect of ionizing radiation. Exposure to even a low dose of radiation during radiotherapy, diagnostic radiology, or a radiological event could pose a threat to spermatogenesis. This may lead to temporary or permanent infertility or even transfer of genomic instability to the next generations. OBJECTIVE: In this study, we evaluated the protective effect of treatment with three natural antioxidants; resveratrol, alpha lipoic acid, and coenzyme Q10 on radiation-induced spermatogenesis injury. MATERIALS AND METHODS: 30 NMRI mice (6-8 wk, 30 ± 5 gr) were randomly divided into six groups (n = 5/each) as 1) control; 2) radiation; 3) radiation + resveratrol; 4) radiation + alpha lipoic acid; 5) radiation + resveratrol + alpha lipoic acid; and 6) radiation+ Q10. Mice were treated with 100 mg/kg resveratrol or 200 mg/kg alpha lipoic acid or a combination of these drugs. Also, Q10 was administered at 200 mg/kg. All treatments were performed daily from two days before to 30 min before irradiation. Afterward, mice were exposed to 2 Gy 60 Co gamma rays; 37 days after irradiation, the testicular samples were collected and evaluated for histopathological parameters. RESULTS: Results showed that these agents are able to alleviate some toxicological parameters such as basal lamina and epididymis decreased sperm density. Also, all agents were able to increase Johnsen score. However, they could not protect against radiation-induced edema, atrophy of seminiferous tubules, and hyperplasia in Leydig cells. CONCLUSION: This study indicates that resveratrol, alpha-lipoic acid, and Q10 have the potential to reduce some of the side effects of radiation on mice spermatogenesis. However, they cannot protect Leydig cells as a source of testosterone and seminiferous tubules as the location of sperm maturation.

NADPH Oxidase as a Target for Modulation of Radiation Response; Implications to Carcinogenesis and Radiotherapy.

BACKGROUND: Radiotherapy is a treatment modality for cancer. For better therapeutic efficiency, it could be used in combination with surgery, chemotherapy or immunotherapy. In addition to its beneficial therapeutic effects, exposure to radiation leads to several toxic effects on normal tissues. Also, it may induce some changes in genomic expression of tumor cells, thereby increasing the resistance of tumor cells. These changes lead to the appearance of some acute reactions in irradiated organs, increased risk of carcinogenesis, and reduction in the therapeutic effect of radiotherapy. DISCUSSION: So far, several studies have proposed different targets such as cyclooxygenase-2 (COX-2), some toll-like receptors (TLRs), mitogen-activated protein kinases (MAPKs) etc., for the amelioration of radiation toxicity and enhancing tumor response. NADPH oxidase includes five NOX and two dual oxidases (DUOX1 and DUOX2) subfamilies that through the production of superoxide and hydrogen peroxide, play key roles in oxidative stress and several signaling pathways involved in early and late effects of ionizing radiation. Chronic ROS production by NOX enzymes can induce genomic instability, thereby increasing the risk of carcinogenesis. Also, these enzymes are able to induce cell death, especially through apoptosis and senescence that may affect tissue function. ROS-derived NADPH oxidase causes apoptosis in some organs such as intestine and tongue, which mediate inflammation. Furthermore, continuous ROS production stimulates fibrosis via stimulation of fibroblast differentiation and collagen deposition. Evidence has shown that in contrast to normal tissues, the NOX system induces tumor resistance to radiotherapy through some mechanisms such as induction of hypoxia, stimulation of proliferation, and activation of macrophages. However, there are some contradictory results. Inhibition of NADPH oxidase in experimental studies has shown promising results for both normal tissue protection and tumor sensitization to ionizing radiation. CONCLUSION: In this article, we aimed to review the role of different subfamilies of NADPH oxidase in radiation-induced early and late normal tissue toxicities in different organs.