Sulforaphane mitigates genotoxicity induced by radiation and anticancer drugs in human lymphocytes

Protective effects of sulforaphane against toxic substances and contaminants: A systematic review

BACKGROUND

Sulforaphane (SFN) is a dietary isothiocyanate, derived from glucoraphanin, present in cruciferous vegetables belonging to the Brassica genus. It is a biologically active phytochemical that acts as a nuclear factor erythroid 2-related factor 2 (Nrf2) inducer. Thus, it has been reported to have multiple protective functions including anticancer responses and protection against a toxic agent's action.

PURPOSE

The present work systematically reviewed and synthesised the protective properties of sulforaphane against a toxic agent. This review reveals the mechanism of the action of SFN in each organ or system.

METHODS

The PRISMA guideline was followed in this sequence: researched literature, organised retrieved documents, abstracted relevant information, assessed study quality and bias, synthesised data, and prepared a comprehensive report. Searches were conducted on Science Direct and PubMed using the keywords "Sulforaphane" AND ("protective effects" OR "protection against").

RESULTS

Reports showed that liver and the nervous system are the target organs on which attention was focused, and this might be due to the key role of oxidative stress in liver and neurodegenerative diseases. However, protective activities have also been demonstrated in the lungs, heart, immune system, kidneys, and endocrine system. SFN exerts its protective effects by activating the Nrf2 pathway, which enhances antioxidant defenses and reduces oxidative stress. It also suppresses inflammation by decreasing interleukin production. Moreover, SFN inhibits apoptosis by preventing caspase 3 cleavage and increasing Bcl2 levels. Overall, SFN demonstrates multifaceted mechanisms to counteract the adverse effects of toxic agents.

CONCLUSION

SFN has potential clinical applications as a chemoprotective agent. Nevertheless, more studies are necessary to set the safe doses of SFN in humans.

Mitigation of radiation injury to reproductive system of male mice by Trichostatin A

Trichostatin A (TSA), derived from the bacteria Streptomyces hygroscopicus, is a hydroxamic acid having various biological properties such as histone deacetylase inhibition, anticancer and radiomitigative action. However the mitigative activity of TSA against radiation-induced damages in the mouse reproductive system has not yet been elucidated. The present study unraveled the effects of 2 Gy whole body irradiation (⁶⁰Co γ- radiation) on C57BL/6 mice male reproductive system including structural damages to testes, increase in apoptosis and reduction in germ cell viability, reduced fertility as well as increased genomic instability in the next generation. Moreover, hematological study and micronuclei assay were used to record chances of radiation-induced hematologic cancer and disruption of genomic integrity in F₁ generation. Interestingly, TSA administration 1 and 24 h post-irradiation attenuated radiation-induced morphological damage and cellular apoptosis in testes. In male mice, TSA restored hematological parameters and micronuclei frequency to normal levels, restored sperm viability, and helped them overcome radiation-induced temporary sterility 5 weeks after the irradiation. Thus our results showed that TSA reduced the probability of radiation-induced hematologic cancers as well as genotoxicity and restored genomic integrity in the progenies of paternally exposed mice by reducing radiation-induced apoptosis in spermatogenic cells and restoring cell proliferation. This study suggested that TSA could be used as potential radiomitigator for male reproductive system.

The Hematopoietic Function of Medicinal Wine Maoji Jiu Revealed in Blood Deficiency Model Rats

Maoji Jiu (MJ), a medicinal wine, has been used commonly by the Chinese to enrich and nourish the blood. In this study, the aim is to examine the hematopoietic function of MJ and investigate its hematopoietic regulation mechanism. Thirty-six female Sprague-Dawley rats (200 ± 20 g) were randomly divided into six groups with six rats in each group. The blood deficiency model was induced by injecting hypodermically with N-acetylphenylhydrazine (APH) and injecting intraperitoneally with cyclophosphamide (CTX), and treatment drugs were given by oral gavage twice a day for continuous 10 days from the start of the experiments. The administration of MJ improved the levels of white blood cells (WBCs), red blood cells (RBCs), hemoglobin (HGB), and hematocrit (HCT) in the blood deficiency model rats. Hematopoietic effect involves regulating the antioxidant activity in the liver and the levels of Bcl-2, Bax, erythropoietin (EPO), transforming growth factor-beta-1 (TGF-β1), and macrophage colony-stimulating factor (M-CSF) mRNA in spleen tissues to enhance extramedullary hematopoiesis. This study suggests that MJ has a beneficial effect on blood deficiency model rats.

Quercetin Alleviates the Immunotoxic Impact Mediated by Oxidative Stress and Inflammation Induced by Doxorubicin Exposure in Rats

Doxorubicin (DOX) is a chemotherapeutic agent against hematogenous and solid tumors with undesirable side effects including immunosuppression. Quercetin (QUR), a natural flavonoid abundant in fruits and vegetables, has a potent antioxidant activity. The aim of the current study was to assess the impact of QUR on DOX-induced hematological and immunological dysfunctions in a rodent model. Randomly grouped rats were treated as follows: control, QUR alone (50 mg/kg for 15 days per os), DOX alone (2.5 mg/kg I/P, three times a week, for two weeks), and co-treated rats with QUR for 15 days prior to and concomitantly with DOX (for two weeks), at the doses intended for groups two and three. DOX alone significantly disrupted the erythrogram and leukogram variables. Serum immunoglobulin (IgG, IgM, and IgE) levels and the activities of catalase (CAT) and superoxide dismutase (SOD) in spleen were declined. The DNA damage traits in spleen were elevated with an upregulation of the expression of the apoptotic markers (p53 and Caspase-3 genes) and the proinflammatory cytokines (IL-6 and TNF-α genes), while the expression of CAT gene was downregulated. These biochemical changes were accompanied by morphological changes in the spleen of DOX-treated rats. Co-treatment with QUR abated most of the DOX-mediated alterations in hematological variables, serum immunoglobulins, and spleen antioxidant status, pro-inflammatory and apoptotic responses, and histopathological alterations. In essence, these data suggest that QUR alleviated DOX-induced toxicities on the bone marrow, spleen, and antibody-producing cells. Supplementation of chemotherapy patients with QUR could circumvent the DOX-induced inflammation and immunotoxicity, and thus prevent chemotherapy failure.

Sulforaphane-Mediated Nrf2 Activation Prevents Radiation-Induced Skin Injury through Inhibiting the Oxidative-Stress-Activated DNA Damage and NLRP3 Inflammasome

This article mainly observed the protective effect of sulforaphane (SFN) on radiation-induced skin injury (RISI). In addition, we will discuss the mechanism of SFN's protection on RISI. The RISI model was established by the irradiation of the left thigh under intravenous anesthesia. Thirty-two C57/BL6 mice were randomly divided into control group (CON), SFN group, irradiation (IR) group, and IR plus SFN (IR/SFN) group. At eight weeks after irradiation, the morphological changes of mouse skin tissues were detected by H&E staining. Then, the oxidative stress and inflammatory response indexes in mouse skin tissues, as well as the expression of Nrf2 and its downstream antioxidant genes, were evaluated by ELISA, real-time PCR, and Western blotting. The H&E staining showed the hyperplasia of fibrous tissue in the mouse dermis and hypodermis of the IR group. Western blotting and ELISA results showed that the inflammasome of NLRP3, caspase-1, and IL-1β, as well as oxidative stress damage indicators ROS, 4-HNE, and 3-NT, in the skin tissues of mice in the IR group were significantly higher than those in the control group (p < 0.05). However, the above pathological changes declined sharply after SFN treatment (p < 0.05). In addition, the expressions of Nrf2 and its regulated antioxidant enzymes, including CAT and HO-1, were higher in the skin tissues of SFN and IR/SFN groups, but lower in the control and IR groups (p < 0.05). SFN may be able to suppress the oxidative stress by upregulating the expression and function of Nrf2, and subsequently inhibiting the activation of NLRP3 inflammasome and DNA damage, so as to prevent and alleviate the RISI.

Trichostatin A mitigates radiation induced teratogenesis in C57 Bl/6 mice

Radiation exposure in utero is known to lead to serious concerns to both the mother and children, including developmental anomalies in the children. In the recent past trichostatn A, an HDAC inhibitor and epigenetic modifier, has been shown to mitigate radiation induced anomalies in the male reproductive system of C57BL/6 mice. Therefore, the current study was undertaken to evaluate the mitigating effects of trichostatin A against radiation induced developmental anomalies in mice. Fetuses of in utero whole body gamma irradiated mice during active organogenesis period were examined for developmental anomalies on 8.5 and 18.5 day of gestation. In utero radiation exposure caused developmental anomalies like microcephaly, microphthalamia, gastroschisis and kinky tail besides prenatal mortality. Trichostatin A administration post irradiation was observed to reduce 50% of prenatal mortality at E18.5 by reducing congenital and developmental anomalies. Observation of such results could be corroborated with the HDAC inhibitory potential of trichostatin A knowing that developmental anomalies may have epigenetic origin. Trichostatin A therefore can be considered as a potential radiomitigator.

Mechanism of Action of Diallyl Sulphide in Ameliorating the Hematopoietic Radiation Injury

Diallyl sulphide (DAS), the pungent component of garlic, is known to have several medicinal properties and has recently been shown to have radiomitigative properties. The present study was performed to better understand its mode of action in rendering radiomitigation. Evaluation of the colonogenic ability of hematopoietic progenitor cells (HPCs) on methocult media, proliferation and differentiation of hematopoietic stem cells (HSCs), and transplantation of stem cells were performed. The supporting tissue of HSCs was also evaluated by examining the histology of bone marrow and in vitro colony-forming unit–fibroblast (CFU-F) count. Alterations in the levels of IL-5, IL-6 and COX-2 were studied as a function of radiation or DAS treatment. It was observed that an increase in proliferation and differentiation of hematopoietic stem and progenitor cells occurred by postirradiation DAS administration. It also resulted in increased circulating and bone marrow homing of transplanted stem cells. Enhancement in bone marrow cellularity, CFU-F count, and cytokine IL-5 level were also evident. All those actions of DAS that could possibly add to its radiomitigative potential and can be attributed to its HDAC inhibitory properties, as was observed by the reversal radiation induced increase in histone acetylation.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

Developing polyphenolic acetates as radiation countermeasure agents: current status and future perspectives

Total-body exposure to ionizing radiation (TBI) results in life-threatening acute radiation syndrome (ARS), which encompasses hematopoietic and gastrointestinal (GI) injuries and results in dose-dependent morbidity and mortality. Management of ARS warrants the deployment of effective medical countermeasure agents (MCM) that protect against and/or mitigate lethal radiation injury. The polyphenolic acetate (PA) 7,8-diacetoxy-4-methylthiocoumarin (DAMTC) has been identified as a potential MCM against ARS by virtue of it mitigating the lethal effects of TBI in C57BL/6 mice. Herein, we describe current evidence, including mechanistic aspects, for the use of PAs as MCMs against ARS and provide perspectives for their further development as approved drugs for the mitigation of ARS.

Combinations of the antioxidants sulforaphane or curcumin and the conventional antineoplastics cisplatin or doxorubicin as prospects for anticancer chemotherapy

Drugs used in clinical oncology have narrow therapeutic indices with adverse toxicity often involving oxidative damage. Chemoresistance to these conventional antineoplastics is usually mediated by oxidative stress-upregulated pathways such as those of nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor-1 alpha (HIF-1α). Accordingly, the use of antioxidants in combinational approaches has begun to be considered for fighting cancer because of both the protective role against adverse effects and the ability to sensitize chemoresistant cancer cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been identified as a mediator of the cytoprotection but it is not regularly associated with tumor chemosensitization. However, some Nrf2 inducers could be exerting cytoprotective and chemosensitizing roles through a simple integrated mechanism in which the cellular level of reactive oxygen species is controlled, thus inhibiting the oxidative damage in non-target tissues and the tumor chemoresistance mediated by NF-κB or HIF-1α. As examples to show the general idea of this antioxidant combination chemotherapy, this review explores the preclinical information available for four combinations, each composed by a paradigmatic oncological drug (cisplatin or doxorubicin) and a recognized antioxidant (sulforaphane or curcumin). The issues for translating these outcomes to clinical trials are briefly discussed.

In the triple-negative breast cancer MDA-MB-231 cell line, sulforaphane enhances the intracellular accumulation and anticancer action of doxorubicin encapsulated in liposomes

A new combination of sulforaphane (a natural compound obtained from Brassicaceae vegetables) and the cytostatic drug doxorubicin was entrapped in nanometer-sized liposomes. In vitro experiments were performed to investigate the cytotoxicity of these structures on the human breast cancer cell line MDA-MB-231. Confocal microscopy studies revealed enhanced cellular endocytotic internalization, followed by the release of the examined combination from the lysosomes. The in vitro interaction analysis using the Chou-Talalay approach showed high synergistic activity of the examined combination. This synergistic activity enables a considerable reduction in cytostatic dosage and an increase in cancer treatment efficiency.

Trichostatin A, an epigenetic modifier, mitigates radiation-induced androphysiological anomalies and metabolite changes in mice as evident from NMR-based metabolomics

PURPOSE

Ionizing radiation is known to damage male reproductive system. Current study aims to study the mitigative effects of trichostatin A on male reproductive system and accompanying metabolite changes in testicular tissue of mice.

MATERIALS AND METHODS

Eight-week-old male C57 Bl/6J mice were exposed to 2 Gy γ-radiation with or without trichostatin A administration. The animals were sacrificed at various time intervals for organ body weight index, sperm head abnormality assay, sperm mobility assay, and study of various metabolites in testicular tissue using NMR spectroscopy.

RESULTS

Ionizing radiation induced no significant change in organ body weight index at any time points studied, however a significant increase in sperm head abnormality and significant decrease in sperm mobility was evident on fifth postirradiation week. trichostatin A administration, 1 and 24 h postirradiation, could efficiently mitigate radiation-induced changes studied. NMR metabolome profile also showed prominent changes associated with energy metabolism, osmolytes and membrane metabolism at 24 h postirradiation and some of these changes (choline, glycerolphosphoethanol amine, and glycine) were persistent till fifth postirradiation week. Trichostatin A administration resulted in reverting metabolic profile of the irradiated animals to normal level suggesting its mitigative role.

CONCLUSION

Results obtained suggest that trichostatin A could restore normal metabolic profile of testicular tissue of irradiated male mice and also restored certain morphological and functional properties of sperms. Trichostatin A thus could further be exploited for its radio-mitigative properties.

Assessment of sulforaphane-induced protective mechanisms against cadmium toxicity in human mesenchymal stem cells

Cd is a hazardous substance and carcinogen that is present in the environment; it is known to cause toxic effects in living organisms. Sulforaphane is a naturally available phytochemical with antioxidant, anti-inflammatory, and anticarcinogenic properties. However, the effects of sulforaphane on Cd toxicity in human mesenchymal stem cells (hMSCs) are unknown. In the present study, we investigated the molecular mechanisms of the effects of sulforaphane on Cd toxicity in hMSCs by using MTT assays, acridine orange/ethidium bromide staining, Hoechst staining, LysoRed staining, assessment of mitochondrial membrane potential, and gene expression analysis. Cd decreased hMSC viability in a dose-dependent manner with an IC₅₀ value of 56.5 μM. However, sulforaphane did not induce any significant reduction in cell viability. Nuclear morphological analysis revealed that Cd induced necrotic cell death. Additionally, Cd caused mitochondrial membrane potential loss in hMSCs. The treatment of Cd-exposed cells with sulforaphane (Cd-sulforaphane co-treatment) resulted in a significant recovery of the cell viability and nuclear morphological changes compared with that of cells treated with Cd only. The gene expression pattern of cells co-treated with Cd-sulforaphane was markedly different from that of Cd-treated cells, owing to the reduction in Cd toxicity. Our results clearly indicated that sulforaphane reduced Cd-induced toxic effects in hMSCs. Overall, the results of our study suggested that sulforaphane-rich vegetables and fruits can help to improve human health through amelioration of the molecular effects of Cd poisoning.

Immunological Aspect of Radiation-Induced Pneumonitis, Current Treatment Strategies, and Future Prospects

Delivery of high doses of radiation to thoracic region, particularly with non-small cell lung cancer patients, becomes difficult due to subsequent complications arising in the lungs of the patient. Radiation-induced pneumonitis is an early event evident in most radiation exposed patients observed within 2-4 months of treatment and leading to fibrosis later. Several cytokines and inflammatory molecules interplay in the vicinity of the tissue developing radiation injury leading to pneumonitis and fibrosis. While certain cytokines may be exploited as biomarkers, they also appear to be a potent target of intervention at transcriptional level. Initiation and progression of pneumonitis and fibrosis thus are dynamic processes arising after few months to year after irradiation of the lung tissue. Currently, available treatment strategies are challenged by the major dose limiting complications that curtails success of the treatment as well as well being of the patient's future life. Several approaches have been in practice while many other are still being explored to overcome such complications. The current review gives a brief account of the immunological aspects, existing management practices, and suggests possible futuristic approaches.

Role of some epigenetic factors in DNA damage response pathway

The current review gives a brief account of the DNA damage response pathway and involvement of various epigenetic mechanisms in DNA damage response pathway. The main focus is on histone modifications leading to structural alterations in chromatin since the compact chromatin structure poses a major limitation in the DNA repair process. Based on this hypothesis, our laboratory has also evaluated certain histone deacetylase inhibitors as potential radiomitigators and the same has been discussed in brief at the end of the review.

Dose response and adaptive response of non-homologous end joining repair genes and proteins in resting human peripheral blood mononuclear cells exposed to γ radiation

Ionising radiation induces single-strand breaks, double-strand breaks (DSB) and base damages in human cell. DSBs are the most deleterious and if not repaired may lead to genomic instability and cell death. DSB can be repaired through non-homologous end joining (NHEJ) pathway in resting lymphocytes. In this study, NHEJ genes and proteins were studied in irradiated human peripheral blood mononuclear cells (PBMC) at resting stage. Dose-response, time point kinetics and adaptive-response studies were conducted in irradiated PBMC at various end points such as DNA damage quantitation, transcription and protein expression profile. Venous blood samples were collected from 20 random, normal and healthy donors with written informed consent. PBMC was separated and irradiated with various doses between 0.1 and 2.0 Gy ((60)CO-γ source) for dose-response study. Repair kinetics of DNA damage and time point changes in expression of genes and proteins were studied in post-irradiated PBMC at 2.0 Gy at various time points up to 240 min. Adaptive-response study was conducted with a priming dose of 0.1 Gy followed by a challenging dose of 2.0 Gy after 4-h incubation. Our results revealed that Ku70, Ku80, XLF and Ligase IV were significantly upregulated (P < 0.05) at 4-h post-irradiation at transcript and protein level. Adaptive-response study showed significantly increased expression of the proteins involved in NHEJ, suggesting their role in adaptive response in human PBMC at G0/G1, which has important implications to human health.

Sulforaphane reverses glucocorticoid-induced apoptosis in osteoblastic cells through regulation of the Nrf2 pathway

Apoptosis of osteoblasts triggered by high-dose glucocorticoids (GCs) has been identified as a major cause of osteoporosis. However, the underlying molecular mechanisms accounting for this action remain elusive, which has impeded the prevention and cure of this side effect. Sulforaphane (SFP) is a naturally occurring isothiocyanate that has huge health benefits for humans. In this study, by using osteoblastic MC3T3-E1 cells as a model, we demonstrate the protective effects of SFP against dexamethasone (Dex)-induced apoptosis and elucidate the underlying molecular mechanisms. The results show that SFP could effectively inhibit the Dex-induced growth inhibition and release of lactate dehydrogenase in MC3T3-E1 cells. Treatment with Dex induced caspase-dependent apoptosis in MC3T3-E1 cells, as evidenced by an increase in the Sub-G1 phase, chromatin condensation, and deoxyribonucleic acid fragmentation, which were significantly suppressed by coincubation with SFP. Mitochondria-mediated apoptosis pathway contributed importantly to Dex-induced apoptosis, as revealed by the activation of caspase-3/-9 and subsequent cleavage of poly adenosine diphosphate ribose polymerase, which was also effectively blocked by SFP. Moreover, treatments of Dex strongly induced overproduction of reactive oxygen species and inhibited the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and the downstream effectors HO1 and NQO1. However, cotreatment with SFP effectively reversed this action of Dex. Furthermore, silencing of Nrf2 by small interfering ribonucleic acid significantly blocked the cytoprotective effects of SFP against Dex-induced apoptosis, which suggest the important role of Nrf2 signaling pathway and cell apoptosis induced by Dex. Taken together, this study provides a novel strategy for molecular intervention against Dex-induced osteoporosis using phytochemicals.