Anticlastogenic and antigenotoxic effects of selenomethionine on doxorubicin-induced damage in vitro in human lymphocytes

Impact of platelet-rich plasma versus selenium in ameliorating induced toxicity in rat testis: histological, immunohistochemical, and molecular study

This study was conducted on forty adult rats divided into four groups: Group I (control) that is divided into subgroups A, B, and C and Group II (methotrexate (MTX)-treated); the rats were injected intraperitoneally with MTX at a dose of 1 mg/kg/week, for 8 weeks. Group III (MTX-Se co-treated) was injected with MTX like Group II plus an oral administration of selenium at a dose of 10 μg/kg b.w/day, for 8 weeks. Group IV (MTX-PRP co-treated), rats were injected intraperitoneally with MTX like Group II plus platelet-rich plasma (PRP) injection under the scrotum, three times with 2-week intervals (volume-0.1 ml per injection) and euthanized after 8 weeks. Histological, immunohistochemical, and genetic expression using qPCR and western blotting technique were conducted. There was improvement in histological structure of testes in most specimens of Group IV. The latter group revealed a significant decrease in Bax and an increase in Bcl-2. The regeneration of testicular tissue was more observed in Group IV as measured by an increase in mean number of PCNA. Moreover, Group IV revealed an increased genetic level of FSCN3, GCNF, UBQLN3, and DAZL. Both MTX-Se and MTX-PRP have an anti-inflammatory effect as measured by a reduction in NF-κb. The anti-oxidative effect of selenium and PRP was noticed by a decrease in the level of the iNos and an increase in eNos protein and the autophagy marker LC3. PRP has ameliorative effects on induced rat testicular toxicity as evaluated by morphological changes and confirmed by immunohistochemical reactions, genetic expression, and western blotting analyses including oxidative and anti- oxidative markers.

Anticancer potential, molecular mechanisms and toxicity of Euterpe oleracea extract (açaí): A systematic review

Cancer is an increasingly frequent malignancy worldwide, and despite the advances in drug development, it is still necessary to develop new plant-derived medicines. Euterpe oleracea (açaí) is abundant in South and Central America and has health benefits due to its high levels of phytochemicals, including lignans and polyphenols. The aim of this review was to systematically describe the safety and antitumor effects of açaí in preclinical models using rodents to provide a more comprehensive assessment of açaí for both therapeutic uses and the development of future clinical studies in cancer. Eligible studies were identified using four international databases (PubMed, Medline, Lilacs and SciELO) from their inception date through December 2017. The included studies were analyzed with methodological rigor (QATRS) to enable better quality control for these experimental studies. Sixty publications were identified in the databases, but only 9 articles were eligible: 6 evaluated the pharmacological effects of açaí in animal models of cancer (1 model each of esophageal cancer, urothelial cancer, melanoma and Walker-256 tumor and 2 models of colon cancer), and 3 were toxicological assays using preclinical models with rodents. Overall, 747 animals were analyzed. On a QATRS score scale of 0-20, the quality of the studies ranged from 16 to 20 points. Pulp was the main fraction of açaí administered, and an oral administration route was most common. The açaí dosage administered by gavage ranged from 30 mg/kg to 40,000 mg/kg, and açaí fed in the diet accounted for 2.5% to 5% of the diet. The anticarcinogenic and chemopreventive activities of açaí were observed in all experimental models of cancer and reduced the incidence, tumor cell proliferation, multiplicity and size of the tumors due to the antiinflammatory, antiproliferative and proapoptotic properties of açaí. No genotoxic effects were observed after açaí administration. The results of this review suggest that açaí is safe and can be used as a chemoprotective agent against cancer development. Açaí therapy may be a novel strategy for treating cancer.

Cytotoxicity and genotoxicity of stilbene derivatives in CHO-K1 and HepG2 cell lines

The cytotoxicity and genotoxicity of the stilbenes (E)-methyl-4-(3-5-dimethoxystyryl)benzoate (ester), (E)-4-(3-5-dimethoxystyryl)aniline (amino), (Z)-1,3-dimethoxy-5-(4-methoxystyryl)benzene (cis-TMS) and (E)-1,3-dimethoxy-5-(4-methoxystyryl)benzene (trans-TMS) were investigated in this work. Structural modifications of resveratrol, a naturally occurring stilbene, have been previously performed, including the replacement of hydroxyl by different functional groups. Such modifications resulted in significant improvement of target-specific effects on cell death and antiproliferative responses. The parameters were evaluated using XTT assay, clonogenic survival assay and the cytokinesis-block micronucleus assay in CHO-K1 and HepG2 cell lines. The results showed that cis-TMS is approximately 250-fold more cytotoxic than the amino and ester, and 128-fold more cytotoxic than trans-TMS. When genotoxicity was evaluated, only the trans-TMS did not significantly increase the frequency of micronucleus (MN). While the cis-TMS induced a mean of 5.2 and 5.9 MN/100 cells at 0.5 μM in CHO-K1 and HepG2, respectively, the amino and ester induced 3.1 and 3.6 MN/100 cells at 10 μM in CHO-K1, respectively, and 3.5 and 3.8 in HepG2. Trans-TMS is genotoxic only in HepG2 cells. Based on these results, the cis-TMS was the most cytotoxic and genotoxic compound in both cell lines.

Comparative study of the cytotoxicity and genotoxicity of kaurenoic acid and its semi-synthetic derivatives methoxy kaurenoic acid and kaurenol in CHO-K1 cells

The diterpene kaurenoic acid (KA) has vasorelaxant, antimicrobial, anti-tumoural and anti-leishmanial effects. Semi-synthetic derivatives were obtained to achieve more satisfactory responses. The assessment of genotoxicity is part of the toxicological evaluation of therapeutic compound candidates. The present study investigated the cytotoxicity and genotoxicity of KA and its semi-synthetic derivatives methoxy kaurenoic acid (MKA) and kaurenol (KRN) using the CHO-K1 cell line. The cytotoxicity evaluation demonstrated that treatments with 200 and 400 μM KA reduced cellular proliferation to 36.5 and 4.43%, respectively, and that 100 and 200 μM KA reduced the survival fraction (SF) to 48.1 and 5.5%, respectively. MKA and KRN at concentrations of 400 μM reduced proliferation to 81 and 86.8%, respectively, while 100 and 200 μM KRN reduced the SF to 50%, and 200 μM MKA reduced the SF to 74%. No genotoxicity was observed for KA or MKA. However, 100 μM KRN increased the DNA damage index, as detected by comet assay, although a micronucleus assay did not confirm these data. The results demonstrated that KA and its semi-synthetic derivative MKA were not genotoxic when tested at noncytotoxic concentrations, but KRN was genotoxic at the highest concentration that was tested, as demonstrated by the comet assay.

Combined cytogenotoxic effects of bee venom and bleomycin on rat lymphocytes: an in vitro study

This study was carried out to determine the cytotoxic and genotoxic effects of bee venom (BV) and/or the chemotherapeutic agent bleomycin (BLM) on healthy isolated rat lymphocytes utilizing morphometric and molecular techniques. Using the Ficoll-Histopaque density gradient centrifugation technique, lymphocytes were isolated, divided into groups, and subjected to BV and/or BLM at incubation medium concentrations of 10 or 20 μg/mL respectively for 24 and 72 hrs. An MTT assay and fluorescent microscopy examinations were used to assess the cytotoxic effects. To determine the predominant type of BV and/or BLM-induced cell death, LDH release assay was employed beside quantitative expression analyses of the apoptosis-related genes (Caspase-3 and Bcl-2). The genotoxic effects of the tested compounds were evaluated via DNA fragmentation assay. The results of these assays demonstrated that BV potentiates BLM-induced cytotoxicity through increased LDH release and diminished cell viability. Nevertheless, BV significantly inhibited the BLM-induced DNA damage. The results verify that BV significantly attenuates the genotoxic effects of BLM on noncancerous isolated rat lymphocytes but does not diminish BLM cytotoxicity.

The effects of selenium and the GPx-1 selenoprotein on the phosphorylation of H2AX

BACKGROUND

Significant data supports the health benefits of selenium although supplementation trials have yielded mixed results. GPx-1, whose levels are responsive to selenium availability, is implicated in cancer etiology by human genetic data. Selenium's ability to alter the phosphorylation of the H2AX, a histone protein that functions in the reduction of DNA damage by recruiting repair proteins to the damage site, following exposure to ionizing radiation and bleomycin was investigated.

METHODS

Human cell lines that were either exposed to selenium or were transfected with a GPx-1 expression construct were exposed to ionizing radiation or bleomycin. Phosphorylation of histone H2AX was quantified by flow cytometry and survival by the MTT assay. Phosphorylation of the Chk1 and Chk2 checkpoint proteins was quantified by western blotting.

RESULTS

In colon-derived cells, selenium increases GPx-1 and attenuated H2AX phosphorylation following genotoxic exposures while the viability of these cells was unaffected. MCF-7 cells and transfectants that express high GPx-1 levels were exposed to ionizing radiation and bleomycin, and H2AX phosphorylation and cell viability were assessed. GPx-1 increased H2AX phosphorylation and viability following the induction of DNA damage while enhancing the levels of activated Chk1 and Chk2.

CONCLUSIONS

Exposure of mammalian cells to selenium can alter the DNA damage response and do so by mechanisms that are dependent and independent of its effect on GPx-1.

GENERAL SIGNIFICANCE

Selenium and GPx-1 may stimulate the repair of genotoxic DNA damage and this may account for some of the benefits attributed to selenium intake and elevated GPx-1 activity.

Does a role for selenium in DNA damage repair explain apparent controversies in its use in chemoprevention?

The trace element selenium is an essential micronutrient that has received considerable attention for its potential use in the prevention of cancer. In spite of this interest, the mechanism(s) by which selenium might function as a chemopreventive remain to be determined. Considerable experimental evidence indicates that one possible mechanism by which selenium supplementation may exert its benefits is by enhancing the DNA damage repair response, and this includes data obtained using cultured cells, animal models as well as in human clinical studies. In these studies, selenium supplementation has been shown to be beneficial in reducing the frequency of DNA adducts and chromosome breaks, consequentially reducing the likelihood of detrimental mutations that ultimately contribute to carcinogenesis. The benefits of selenium can be envisioned as being due, at least in part, to it being a critical constituent of selenoproteins such as glutathione peroxidases and thioredoxin reductases, proteins that play important roles in antioxidant defence and maintaining the cellular reducing environment. Selenium, therefore, may be protective by preventing DNA damage from occurring as well as by increasing the activity of repair enzymes such as DNA glycosylases and DNA damage repair pathways that involve p53, BRCA1 and Gadd45. An improved understanding of the mechanism of selenium's impact on DNA repair processes may help to resolve the apparently contradicting data obtained from decades of animal work, human epidemiology and more recently, clinical supplementation studies.

Antimutagenic effect of aqueous extract from Agaricus brasiliensis on culture of human lymphocytes

The mushroom Agaricus brasiliensis (sun mushroom), native from the southeast of Brazil, is well known by its medicinal properties that include effects on diabetes, cholesterol levels, and osteoporosis. The antimutagenic effects of A. brasiliensis has been investigated recently and revealed some controversial results depending on the temperature by which the A. brasiliensis tea is obtained. In the present study, we evaluated the effect of the A. brasiliensis extract prepared in two different temperatures, 4°C and 25°C, on the doxorubicin-induced DNA strand breaks and chromosomal aberrations (CAs) in human lymphocytes. The results demonstrated that A. brasiliensis was able to reduce the DXR-induced DNA damage in both temperatures; however, the CA test was more sensitive to demonstrate a better reduction when the cells were treated with an extract obtained at 25°C. A. brasiliensis extract obtained in different temperatures exhibited antigenotoxic and anticlastogenic effects in human lymphocytes.

A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins

In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.

Effect of selenium on carbimazole-induced testicular damage and oxidative stress in albino rats

Carbimazole is an antithyroid drug used in treatment of hyperthyroidism. The present investigation studied the effect of carbimazole on testicular activity in albino rats and the ameliorative role of selenium. Treating rats with carbimazole (1.35 mg/kg b.w) daily for 8 weeks caused reduction in the body and testes weight. Moreover, the diameters of the seminiferous tubules and heights of their germinal epithelium were significantly reduced. Testes of treated rats showed many histological alterations included congestion of blood vessels, hemorrhage, degeneration of interstitial tissue and degeneration of spermatogenic cells with apoptosis and necrosis. Histochemical results revealed reduction in polysaccharides, total proteins and nucleic acids contents in testicular tissue. In addition, the level of testosterone, luteinizing hormone (LH), T(3), T(4) and thyroid stimulating hormone (TSH) was significantly decreased in sera of treated animals. Moreover, a high lipid peroxidation with a decrease in the enzymatic antioxidant status, superoxide dismutase (SOD) and catalase (CAT) was recorded in testes homogenate. Treating animals with carbimazole and selenium showed an improvement in the histological structure as well as histochemical components of the testis with an increase in the number of spermatogenic cells. There was an increase in testosterone, LH, T(3), T(4) and TSH levels. Moreover, administration of selenium led to decrease in malondialdehyde and increase in catalase and superoxide dismutase activities. It is suggested that the curative effect of selenium against testicular damage induced by carbimazole may be due to its antioxidant properties.

Distribution and translocation of selenium from soil to grain and its speciation in paddy rice (Oryza sativa L.)

Selenium, an essential micronutrient for humans, is insufficient in dietary intake for millions of people worldwide. Rice as the most popular staple food in the world is one of the dominant selenium (Se) sources for people. The distribution and translocation of Se from soil to grain were investigated in a Se-rich environment in this study. The Se levels in soils ranged widely from 0.5 to 47.7 mg kg(-1). Selenium concentration in rice bran was 1.94 times higher than that in corresponding polished rice. The total Se concentrations in the rice fractions were in the following order: straw>bran>whole grain>polished rice>husk. Significant linear relationships between different rice fractions were observed with each other, and Se in the soil has a linear relationship with different rice fractions as well. Se concentration in rice can easily be predicted by soil Se concentrations or any rice fractions and vice versa according to their linear relationships. In all rice samples for Se speciation, SeMet was the major Se species, followed by MeSeCys and SeCys. The average percentage for SeMet (82.9%) and MeSeCys (6.2%) was similar in the range of total Se from 2.2 to 8.4 mg kg(-1) tested. The percentage of SeCys decreased from 6.3 to 2.8%, although its concentration elevated with the increase in total Se in rice. This could be due to the fact that SeCys is the precursor for the formation of other organic Se compounds. The information obtained may have considerable significance for assessing translocation and accumulation of Se in plant.

The organic selenium compound selenomethionine modulates bleomycin-induced DNA damage and repair in human leukocytes

The objective of this work was to evaluate the effects of selenomethionine (SeMet) on the induction, repair, and persistence of DNA damage in human leukocytes challenged with bleomycin (BLM). Comet assay was used to determine DNA strand breaks and hOGG1 for the specific recognition of oxidative damage. Leukocytes were (A) stimulated with phytohemagglutinin, (B) damaged with BLM, and (C) incubated to allow DNA repair. Comet assay was performed after each phase. SeMet (50 microM) was supplemented either during phase A, B, or C, or AB, or ABC. Treatment with SeMet decreased BLM-induced stand breaks when added during phase AB. Results obtained after the repair period indicate that SeMet favors repair of DNA damage especially when applied during phase AB. The comparison between DNA damage before and after repair showed that BLM-induced damage was repaired better in the presence of SeMet. Our results showed antigenotoxic effect of SeMet on BLM-induced DNA and also on repair and persistence of this damage when applied before and simultaneously with BLM.

Recent advances in protection against doxorubicin-induced toxicity

Anthracycline antibiotics are among the most effective and commonly used anticancer drugs. Unfortunately, their clinical use is restricted by dose-dependent toxicity. Doxorubicin is an anthracycline antibiotic and cytotoxic (antineoplastic) agent. It is commonly used against ovarian, breast, lung, uterine and cervical cancers, Hodgkin's disease, soft tissue and primary bone sarcomas, as well against in several other cancer types. It has been shown that free radicals are involved in doxorubicin-induced toxicity. Doxorubicin causes the generation of free radicals and the induction of oxidative stress, associated with cellular injury. This review illustrates recent applications of different natural products, drugs, drug delivery systems, and approaches for protection against doxorubicin-induced toxicity (2006-present).