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1.
PLoS One ; 15(8): e0228525, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822344

RESUMO

The toxic effect of strained hydrocarbon 2,2'-bis (bicyclo[2.2.1]heptane) (BBH) was studied using whole-cell bacterial lux-biosensors based on Escherichia coli cells in which luciferase genes are transcriptionally fused with stress-inducible promoters. It was shown that BBH has the genotoxic effect causing bacterial SOS response however no alkylating effect has been revealed. In addition to DNA damage, there is an oxidative effect causing the response of OxyR/S and SoxR/S regulons. The most sensitive to BBH lux-biosensor was E. coli pSoxS-lux which reacts to the appearance of superoxide anion radicals in the cell. It is assumed that the oxidation of BBH leads to the generation of reactive oxygen species, which provide the main contribution to the genotoxicity of this substance.


Assuntos
Compostos Bicíclicos com Pontes/toxicidade , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Mutagênicos/toxicidade , Alquilação/efeitos dos fármacos , Técnicas Biossensoriais , Dano ao DNA , Relação Dose-Resposta a Droga , Escherichia coli/citologia , Escherichia coli/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Regulon/efeitos dos fármacos , Regulon/genética
2.
Mutat Res ; 854-855: 503199, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32660827

RESUMO

The bacterial reverse mutation test (Ames test) is the most commonly used genotoxicity test; it is a primary component of the chemical safety assessment data required by regulatory agencies worldwide. Within the current accepted in vitro genotoxicity test battery, it is considered capable of revealing DNA reactivity, and identifying substances that can produce gene mutations via different mechanisms. The previously published consolidated EURL ECVAM Genotoxicity and Carcinogenicity Database, which includes substances that elicited a positive response in the Ames test, constitutes a collection of data that serves as a reference for a number of regulatory activities in the area of genotoxicity testing. Consequently, we considered it important to expand the database to include substances that fail to elicit a positive response in the Ames test, i.e., Ames negative substances. Here, we describe a curated collection of 211 Ames negative substances, with a summary of complementary data available for other genotoxicity endpoints in vitro and in vivo, plus available carcinogenicity data. A descriptive analysis of the data is presented. This includes a representation of the chemical space formed by the Ames-negative database with respect to other substances (e.g. REACH registered substances, approved drugs, pesticides, etc.) and a description of the organic functional groups found in the database. We also provide some suggestions on further analyses that could be made.


Assuntos
Testes de Carcinogenicidade/normas , Carcinógenos/toxicidade , Bases de Dados Factuais/normas , Testes de Mutagenicidade/normas , Mutagênicos/toxicidade , Resultados Negativos/normas , Animais , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , Gerenciamento de Dados/normas , Humanos
3.
Mutat Res ; 854-855: 503198, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32660822

RESUMO

TiO2 particles are broadly used in daily products, including cosmetics for their UV-absorbing property, food for their white colouring property, water and air purification systems, self-cleaning surfaces and photoconversion electrical devices for their photocatalytic properties. The toxicity of TiO2 nano- and microparticles has been studied for decades, and part of this investigation has been dedicated to the identification of their potential impact on DNA, i.e., their genotoxicity. This review summarizes data retrieved from their genotoxicity testing during the past 6 years, encompassing both in vitro and in vivo studies, mostly performed on lung and intestinal models. It shows that TiO2 particles, both nano- and micro-sized, produce genotoxic damage to a variety of cell types, even at low, realistic doses.


Assuntos
Mutagênicos/toxicidade , Titânio/toxicidade , Animais , DNA/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Humanos , Testes de Mutagenicidade/métodos
4.
Mutat Res ; 854-855: 503209, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32660823

RESUMO

We have measured the toxicity and genotoxicity of 2-methylfuran, which is formed in foods during thermal processing. The agent was administered by oral gavage to male Sprague-Dawley rats, daily for 28 days, before performing general toxicology analysis and the following genotoxicity tests: comet assay (peripheral blood, liver); Pig-a gene mutation assay (peripheral blood); micronucleus test (peripheral blood, bone marrow). Liver was the primary target organ; histological changes (oval cell hyperplasia) were observed but without significant changes in serum enzyme markers. For hepatotoxicity, the no-observed-adverse-effect level was 5 mg/kg bw/d. Histopathological changes were also seen in the bone marrow. Genotoxicity assays were uniformly negative.


Assuntos
Furanos/toxicidade , Animais , Ensaio Cometa , Dano ao DNA/efeitos dos fármacos , Fígado/efeitos dos fármacos , Masculino , Testes para Micronúcleos/métodos , Testes de Mutagenicidade/métodos , Mutagênicos/toxicidade , Ratos , Ratos Sprague-Dawley
5.
Toxicon ; 185: 104-113, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32653416

RESUMO

Fungi produce mycotoxins in the presence of appropriate temperature, humidity, sufficient nutrients and if the density of the mushroom mass is favorable. Although all mycotoxins are of fungal origin, all toxic compounds produced by fungi are not called mycotoxins. The interest in mycotoxins first started in the 1960s, and today the interest in mycotoxin-induced diseases has increased. To date, 400 mycotoxins have been identified and the most important species producing mycotoxins belongs to Aspergillus, Penicillium, Alternaria and Fusarium genera. Mycotoxins are classified as hepatotoxins, nephrotoxins, neurotoxins, immunotoxins etc. In this review genotoxic and also other health effects of some major mycotoxin groups like Aflatoxins, Ochratoxins, Patulin, Fumonisins, Zearalenone, Trichothecenes and Ergot alkaloids were deeply analyzed.


Assuntos
Mutagênicos/toxicidade , Micotoxinas/toxicidade , Aflatoxinas/toxicidade , Aspergillus , Dano ao DNA , Contaminação de Alimentos , Microbiologia de Alimentos , Fumonisinas/toxicidade , Fungos , Fusarium , Ocratoxinas/análise , Patulina , Tricotecenos/toxicidade , Zearalenona/toxicidade
6.
Toxicol Lett ; 332: 202-212, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32659469

RESUMO

A variety of methods have been developed for accurate and systematic evaluation of chemical genotoxicity. Ceric ammonium nitrate (CAN) and 1,3-propane sultone (1,3-PS) have been extensively applied in industrial fields. Although 1,3-PS, but not CAN, has been reported as a potent carcinogen, systematic assessment of the genotoxic properties of these chemicals has not been conducted. The purpose of this study was to establish a decision tree for evaluating genotoxicity based on the good laboratory practices (GLP) system using 1,3-PS and CAN as test chemicals. In vitro studies were performed including the bacterial reverse mutation assay, chromosomal aberration assay, and micronucleus assay. We conducted in vivo studies using a combined micronucleus and alkaline comet (MN-CMT) assay and the Pig-a gene mutation assay, which is a promising method for detecting gene mutations in vivo. CAN showed negative responses in all in vitro genotoxicity assays and the in vivo combined MN-CMT assay. Meanwhile, 1,3-PS had positive results in all in vitro and in vivo genotoxicity assays. In this study, we confirmed the genotoxicity of 1,3-PS and CAN using both in vitro and in vivo assays. We propose a decision tree for evaluating chemical-induced genotoxicity.


Assuntos
Cério/toxicidade , Árvores de Decisões , Mutagênicos/toxicidade , Tiofenos/toxicidade , Animais , Bactérias/efeitos dos fármacos , Linhagem Celular/efeitos dos fármacos , Aberrações Cromossômicas/efeitos dos fármacos , Ensaio Cometa , Cricetinae , Cricetulus , Dano ao DNA , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Testes para Micronúcleos , Testes de Mutagenicidade , Ratos Sprague-Dawley
7.
Toxicon ; 184: 192-201, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32569847

RESUMO

Carcinogenic effects of ochratoxin A (OTA) on liver, kidneys, intestine, muscles and subcutaneous tissue of BALB/c albino mice divided in three experimental and one control groups (30 mice in each group - 15 males and 15 females) and exposed to 10 ppm OTA and/or 50-60 ppm penicillic acid (PA) in the diet were seen. A total 22 neoplasias were found to be induced in the mice during 20 months' experimental period. Among them 14 were malignant and 8 benign. The number of neoplasias was significantly higher in the mice treated simultaneously with OTA and PA (14) compared to those in mice treated with OTA only (8). The number of malignant neoplasias was also higher (14) compared to benign neoplasias (8). Nine of a total fourteen malignant neoplasis and five of a total eight benign neoplasias were seen in the male mice. Pathological changes in mice after two weeks' experimental period were characterized by degenerative changes in kidneys, liver and gastrointestinal tract, which were better expressed in the mice exposed simultaneously to OTA and PA. A strong synergistic effect was found between OTA and PA towards tumorogenesis. It seems that mice are not a good experimental model for humans with regard to OTA-induced tumourigenesis, because the target organ of OTA-toxicity in humans or pigs is mainly the kidney, but not the liver, intestines, subcutaneous tissue or muscles as seen in this study.


Assuntos
Mutagênicos/toxicidade , Ocratoxinas/toxicidade , Ácido Penicílico/toxicidade , Animais , Feminino , Humanos , Rim , Fígado , Estudos Longitudinais , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Tamanho do Órgão , Suínos
8.
Toxicol Lett ; 331: 124-129, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32534006

RESUMO

DNA damage quantified as the comet tail length was assessed using in vitro and in vivo comet assay on one- and two-cell mouse embryos obtained by natural mating. The use of a protocol with three layers of agarose reduces the embryo loss and makes it possible to study a small number of embryos. A significantly lower level of basal, but not induced DNA damage was found in embryos with cleaved zona pellucida compared to embryos with intact zona pellucida. There were no significant differences in the length of the comet's tail between embryos lysed in different lysis solutions, both in cases of basal and induced DNA damage. A significant increase in the comet tail length was detected in one-cell embryos of mice treated with methyl methanesulfonate and etoposide compared to the control. The data show that DNA damage induced in maternal germ cells persists, which can be detected in embryos using the comet assay.


Assuntos
Dano ao DNA , Embrião de Mamíferos/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Mutagênicos/toxicidade , Zona Pelúcida/efeitos dos fármacos , Animais , Ensaio Cometa , Embrião de Mamíferos/patologia , Desenvolvimento Embrionário/genética , Feminino , Masculino , Exposição Materna , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Gravidez , Zona Pelúcida/patologia
9.
Mutat Res ; 853: 503173, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32522345

RESUMO

The aryl hydrocarbon receptor (AhR) transcription factor is activated by polycyclic aromatic hydrocarbons (PAH) and other ligands. Activated AhR binds to dioxin responsive elements (DRE) and initiates transcription of target genes, including the gene encoding prostaglandin endoperoxide synthase 2 (PTGS-2), which is also activated by the transcription factor NF-ĸB. PTGS-2 catalyzes the conversion of arachidonic acid (AA) into prostaglandins, thromboxanes or isoprostanes. 15-F2t-Isoprostane (IsoP), regarded as a universal marker of lipid peroxidation, is also induced by PAH exposure. We investigated the processes associated with lipid peroxidation in human alveolar basal epithelial cells (A549) exposed for 4 h or 24 h to model PAH (benzo[a]pyrene, BaP; 3-nitrobenzanthrone, 3-NBA) and organic extracts from ambient air particulate matter (EOM), collected in two seasons in a polluted locality. Both EOM induced the expression of CYP1A1 and CYP1B1; 24 h treatment significantly reduced PTGS-2 expression. IsoP levels decreased after both exposure periods, while the concentration of AA was not affected. The effects induced by BaP were similar to EOM except for increased IsoP levels after 4 h exposure and elevated AA concentration after 24 h treatment. In contrast, 3-NBA treatment did not induce CYP expression, had a weak effect on PTGS-2 expression, and, similar to BaP, induced IsoP levels after 4 h exposure and AA levels after 24 h treatment. All tested compounds induced the activity of NF-ĸB after the longer exposure period. In summary, our data suggest that EOM, and partly BaP, reduce lipid peroxidation by a mechanism that involves AhR-dependent inhibition of PTGS-2 expression. The effect of 3-NBA on IsoP levels is probably mediated by a different mechanism independent of AhR activation.


Assuntos
Células Epiteliais Alveolares/efeitos dos fármacos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Mutagênicos/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Células A549 , Benzo(a)Antracenos/toxicidade , Benzo(a)pireno/toxicidade , Linhagem Celular Tumoral , Ciclo-Oxigenase 1/metabolismo , Citocromo P-450 CYP1A1/metabolismo , Humanos , NF-kappa B/metabolismo , Material Particulado/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/toxicidade
10.
Mutat Res ; 853: 503171, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32522346

RESUMO

The tests used and the general principles behind test strategies are now often over 30 years old. It may be time by now, given that our knowledge of genetic toxicology has improved and that we also technically are better able to investigate DNA damage making use of modern molecular biological techniques, to start thinking on a new test strategy. In the present paper, it is discussed that the time is there to consider a new approach for genotoxicity assessment of substances. A fit for all test strategy was discussed making use of the most recent technological methods and techniques. It was also indicated that in silico tools should be more accepted by regulatory institutes/bodies as supporting information to better conclude which tests should be required for each separate substance to demonstrate its genotoxic potency. Next to that there should be a good rationale for performing in vivo studies. Finally, the need for germ cell genotoxicity testing, essential when classification and labeling of substances is mandatory, was discussed. It was suggested to change the GHS for genotoxicity classification and labelling from in vivo tests in germ cells into in vivo tests in somatic cells. Quantitative genotoxicology was also discussed. It appeared that we are currently at a transition, where the science developing to justify carrying out human health risk assessments based on genetic toxicology data sets supported by mechanistic data and exposure data. However, implementation will take time, and acceptance will be supported through the development of numerous case studies. Major remaining questions are: is genetic damage a relevant endpoint in itself, or should the risk assessment be carried out on the apical endpoint of cancer and which genotoxic endpoint should be used to derive the point of departure (PoD) for the human exposure limit?


Assuntos
Testes de Mutagenicidade/métodos , Testes de Mutagenicidade/normas , Animais , Dano ao DNA/efeitos dos fármacos , Células Germinativas/efeitos dos fármacos , Humanos , Indústrias/métodos , Indústrias/normas , Mutagênicos/toxicidade , Neoplasias/induzido quimicamente , Medição de Risco/métodos , Medição de Risco/normas
11.
Ecotoxicol Environ Saf ; 200: 110761, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32470682

RESUMO

Benzo()pyrene [B()P], widely originated from environmental pollution or food process such as roasting and frying, is a strong mutagen and potent carcinogen. Utilization of hawthorn has been reported against physical mutagens. Our study found that hawthorn extract (HE) contained abundant phenolic compounds, wherein chlorogenic acid was 2.78 mg/g, procyanidine B2 was 3.58 mg/g, epicatechin was 2.99 mg/g DW, which may contribute to anti-genotoxicity activity. So, the role of HE against B()P-induced genotoxicity in C57BL/6 mice was further assessed. Fifty mice were distributed into five groups: control group, B()P group (30 mg/kg, i.p.), B()P + HE-L group (100 mg/kg, i.g.), B()P + HE-M group (200 mg/kg, i.g.), B()P + HE-H group (400 mg/kg, i.g.). Mice were orally administered with solutions of HE for 10 days and injected intraperitoneally with B()P for 3 days from the 8th day. Results showed that B()P can induce significantly pathological damage in liver, lung and spleen, as well as decrease white blood cells (WBCs). Remarkably elevated levels of reactive oxygen species (ROS), DNA strand breaks (DSBs) and G1 cell cycle arrest were also found in B()P group, with upregulated expressions of p-H2AX, p-p53 and p21 in bone marrow cells. With administration of HE, liver, lung and spleen injury significantly mitigated, while WBCs were evidently increased in B()P-treated mice. Consistently, HE markedly reduced level of ROS, DSBs and G1 cell cycle arrest accompanied by reducing expressions of p-H2AX, p-p53 and p21 in bone marrow cells. Combined, these results indicated a protective role of HE on B()P-induced genotoxicity.


Assuntos
Benzo(a)pireno/toxicidade , Crataegus/química , Dano ao DNA/efeitos dos fármacos , Mutagênicos/toxicidade , Extratos Vegetais/farmacologia , Substâncias Protetoras/farmacologia , Animais , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/metabolismo , Expressão Gênica/efeitos dos fármacos , Histonas/genética , Leucócitos/efeitos dos fármacos , Leucócitos/metabolismo , Fígado/efeitos dos fármacos , Fígado/patologia , Pulmão/efeitos dos fármacos , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Extratos Vegetais/isolamento & purificação , Substâncias Protetoras/isolamento & purificação , Espécies Reativas de Oxigênio/metabolismo , Baço/efeitos dos fármacos , Baço/patologia , Proteína Supressora de Tumor p53/genética
12.
PLoS One ; 15(5): e0231355, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437389

RESUMO

The overexploitation of medicinal plants is depleting gene pool at an alarming rate. In this scenario inducing the genetic variability through targeted mutations could be beneficial in generating varieties with increased content of active compounds. The present study aimed to develop a reproducible protocol for in vitro multiplication and mutagenesis of Hyoscyamus niger targeting putrescine N-methyltransferase (PMT) and 6ß-hydroxy hyoscyamine (H6H) genes of alkaloid biosynthetic pathway. In vitro raised callus were treated with different concentrations (0.01% - 0.1%) of Ethyl Methane Sulfonate (EMS). Emerging multiple shoots and roots were obtained on the MS media supplemented with cytokinins and auxins. Significant effects on morphological characteristics were observed following exposure to different concentrations of EMS. EMS at a concentration of 0.03% was seen to be effective in enhancing the average shoot and root number from 14.5±0.30 to 22.2 ±0.77 and 7.2±0.12 to 8.8±0.72, respectively. The lethal dose (LD50) dose was calculated at 0.08% EMS. The results depicted that EMS has an intense effect on PMT and H6H gene expression and metabolite accumulation. The transcripts of PMT and H6H were significantly upregulated at 0.03-0.05% EMS compared to control. EMS treated explants showed increased accumulation of scopolamine (0.639 µg/g) and hyoscyamine (0.0344µg/g) compared to untreated.


Assuntos
Metanossulfonato de Etila/toxicidade , Hiosciamina/metabolismo , Hyoscyamus/crescimento & desenvolvimento , Metiltransferases/genética , Oxigenases de Função Mista/genética , Mutagênese , Mutação , Escopolamina/metabolismo , Vias Biossintéticas , Regulação da Expressão Gênica de Plantas , Hyoscyamus/efeitos dos fármacos , Hyoscyamus/genética , Hyoscyamus/metabolismo , Mutagênicos/toxicidade , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo
13.
PLoS One ; 15(5): e0223344, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32365104

RESUMO

Stilbenes are a group of chemicals characterized with the presence of 1,2-diphenylethylene. Previously, our group has demonstrated that synthesized (E)-N-(2-(3, 5-dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) possesses potential chemopreventive activity specifically inducing NAD(P)H:quinone oxidoreductase 1 (NQO1) protein expression and activity. In this study, the cytoprotective effects of BK3C231 on cellular DNA and mitochondria were investigated in normal human colon fibroblast, CCD-18Co cells. The cells were pretreated with BK3C231 prior to exposure to the carcinogen 4-nitroquinoline 1-oxide (4NQO). BK3C231 was able to inhibit 4NQO-induced cytotoxicity. Cells treated with 4NQO alone caused high level of DNA and mitochondrial damages. However, pretreatment with BK3C231 protected against these damages by reducing DNA strand breaks and micronucleus formation as well as decreasing losses of mitochondrial membrane potential (ΔΨm) and cardiolipin. Interestingly, our study has demonstrated that nitrosative stress instead of oxidative stress was involved in 4NQO-induced DNA and mitochondrial damages. Inhibition of 4NQO-induced nitrosative stress by BK3C231 was observed through a decrease in nitric oxide (NO) level and an increase in glutathione (GSH) level. These new findings elucidate the cytoprotective potential of BK3C231 in human colon fibroblast CCD-18Co cell model which warrants further investigation into its chemopreventive role.


Assuntos
4-Nitroquinolina-1-Óxido/toxicidade , Colo/efeitos dos fármacos , Citoproteção , Dano ao DNA/efeitos dos fármacos , Furanos/farmacologia , Mutagênicos/toxicidade , Estilbenos/farmacologia , Linhagem Celular , Colo/citologia , Reparo do DNA/efeitos dos fármacos , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Furanos/química , Humanos , Mitocôndrias/efeitos dos fármacos , NAD(P)H Desidrogenase (Quinona)/metabolismo , Estilbenos/química
14.
Toxicol Lett ; 329: 67-79, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32387197

RESUMO

This study unveiled the early cellular and molecular events induced by 1,2-dimethylhydrazine (DMH) in the colon and liver and their implications on pre- and neoplastic lesion burden in a late timepoint. Male Wistar rats received four DMH injections (40 mg/kg body weight) for 2 weeks and were sacrificed 24 h (short-term study) or 22 (medium-term study) weeks after the last DMH administration. In the short-term study, DMH led to increased leukocyte (comet assay) and colon (H2AX) genotoxicity, enhanced proliferation (Ki-67) and apoptosis (caspase-3) indexes in both liver and colon. Furthermore, the expression of mRNA (Cat, Gsta1, Gsta2, Gpx1, Gstm1, Sod1, Sod2 and Sod3) and the activity of antioxidant agents were diminished in the colon and liver of DMH-induced rats, eliciting an environment of oxidative stress featuring elevated lipid hydroperoxide levels. Apoptosis effectors were upregulated in the liver (Bax, Casp3 and Fas), and developmental genes were downregulated in both colon and liver (Foxa1, Foxa2, Smad2 and Smad4). In the medium-term study, DMH led to a high number of preneoplastic colonic aberrant crypt foci and tumors (adenomas and invasive adenocarcinomas) but few preneoplastic hepatic glutathione S-transferase (GST-P)-positive foci. Our novel gene expression data highlights overlooked mechanisms in the liver (main metabolizing organ) and colon (main target organ) on toxicity and carcinogenesis induced by repeated doses of DMH, as both organs should be considered in further interventions on the initiation stage of colon carcinogenesis.


Assuntos
1,2-Dimetilidrazina/toxicidade , Carcinógenos/toxicidade , Colo/efeitos dos fármacos , Neoplasias do Colo/induzido quimicamente , Neoplasias Hepáticas/induzido quimicamente , Fígado/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Mutagênicos/toxicidade , Ratos , Ratos Wistar
15.
Toxicol Lett ; 331: 75-81, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32434050

RESUMO

Fungi of the genus Alternaria infest many agricultural crops and produce numerous mycotoxins, of which altertoxin II (ATX II) is one of the most mutagenic metabolites. ATX II carries an epoxide group but the formation of DNA adducts has not been demonstrated to date. We report now that ATX II gives rise to two covalent adducts with guanine when incubated with DNA under cell-free conditions. These adducts were demonstrated by LC-high resolution MS after enzymatic degradation of the incubated DNA to deoxynucleosides. The major adduct results from the covalent binding of ATX II, presumably through the epoxide group, to guanine, whereas the minor guanine adduct is derived from the major one by the elimination of two equivalents of water. In addition, a third adduct was detected, formed through covalent binding of ATX II to cytosine followed by the loss of two equivalents of water. The direct DNA reactivity of ATX II may explain its high mutagenicity.


Assuntos
Benzo(a)Antracenos/toxicidade , Adutos de DNA/análise , DNA/química , Guanina/química , Mutagênicos/toxicidade , Alternaria/química , Animais , Benzo(a)Antracenos/isolamento & purificação , Cromatografia Líquida , DNA/isolamento & purificação , Masculino , Espectrometria de Massas , Salmão , Testículo
16.
Toxicol Lett ; 331: 57-64, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32442718

RESUMO

Electrophilic compounds present in humans, originating from endogenous processes or pollutant exposures, pose a risk to health though their reaction with nucleophilic sites in protein and DNA. Among this chemical class, aldehydes are mainly present in indoor air and they can also be produced by endogenous lipid peroxidation arising from oxidative stress. Known to be very reactive, aldehydes have the ability to form exocyclic adducts to DNA that, for the most if not repaired correctly, are mutagenic and by consequence potential agents involved in carcinogenesis. The aim of this work was to establish profiles of exocyclic DNA adducts induced by aldehyde mixtures, which could ultimately be considered as a genotoxic marker of endogenous and environmental aldehyde exposure. Adducts were quantified by an accurate, sensitive and validated ultra high performance liquid chromatography-electrospray ionization analytical method coupled to mass spectrometry in the tandem mode (UHPLC-ESI-MS/MS). We simultaneously measured nine exocyclic DNA adducts generated during the exposure in vitro of calf thymus DNA to different concentrations of each aldehyde along, as well as, to an equimolar mixture of these aldehydes. This approach has enabled us to establish dose-response relationships that allowed displaying the specific reactivity of aldehydes towards corresponding adducts formation. Profiles of these adducts determined in DNA of current smokers and non-smokers blood samples supported these findings. These first results are encouraging to explore genotoxicity induced by aldehyde mixtures and can furthermore be used as future reference for adductomic approaches.


Assuntos
Aldeídos/toxicidade , Adutos de DNA/sangue , DNA/efeitos dos fármacos , Mutagênicos/toxicidade , Fumar/sangue , Tabaco , DNA/genética , Relação Dose-Resposta a Droga , Humanos , Tabaco/química
17.
Chemosphere ; 254: 126716, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32334246

RESUMO

Cyanobacteria are prokaryotes involved in the contamination of aquatic environments since they release toxins that are highly potent and dangerous for living organisms. Prokaryotes produce endo and exotoxins, among others. Exotoxins are highly toxic, while endotoxins have milder toxic effects. The present study evaluated the cytotoxicogenetic potency of both toxins studying them in different concentrations of cyanobacterial biomasses (1 µg/L, 1.5 µg/L, 2 µg/L), to assess the amount of exotoxin present in the cultured medium in which the cyanobacteria were grown. For this evaluation, we used an extract taken from the medium in a concentration of 10%. Our results showed that genotoxic and mutagenic changes in Allium cepa could be observed in all of the varying concentrations of biomass (endotoxin action) and also in the medium induced with exotoxin. Even at low concentrations, these toxins were highly effective at triggering changes in the DNA molecules of organisms exposed to them. This information is highly significant when considering environmental contamination caused by cyanobacteria blooms, since the results of this study show that these toxins may not only kill organisms when found in high concentrations, but also induce mutations when found in low concentrations. Since these mutations are expressed later on in the organisms, it is impossible to associate the observed effect with the event that induced the damage.


Assuntos
Cianobactérias/patogenicidade , Dano ao DNA , Endotoxinas/toxicidade , Exotoxinas/toxicidade , Biomassa , Microcistinas/toxicidade , Mutagênicos/toxicidade , Cebolas/efeitos dos fármacos
18.
Nucleic Acids Res ; 48(9): 4928-4939, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32297953

RESUMO

Replication factor C (RFC), a heteropentamer of RFC1-5, loads PCNA onto DNA during replication and repair. Once DNA synthesis has ceased, PCNA must be unloaded. Recent findings assign the uloader role primarily to an RFC-like (RLC) complex, in which the largest RFC subunit, RFC1, has been replaced with ATAD5 (ELG1 in Saccharomyces cerevisiae). ATAD5-RLC appears to be indispensable, given that Atad5 knock-out leads to embryonic lethality. In order to learn how the retention of PCNA on DNA might interfere with normal DNA metabolism, we studied the response of ATAD5-depleted cells to several genotoxic agents. We show that ATAD5 deficiency leads to hypersensitivity to methyl methanesulphonate (MMS), camptothecin (CPT) and mitomycin C (MMC), agents that hinder the progression of replication forks. We further show that ATAD5-depleted cells are sensitive to poly(ADP)ribose polymerase (PARP) inhibitors and that the processing of spontaneous oxidative DNA damage contributes towards this sensitivity. We posit that PCNA molecules trapped on DNA interfere with the correct metabolism of arrested replication forks, phenotype reminiscent of defective homologous recombination (HR). As Atad5 heterozygous mice are cancer-prone and as ATAD5 mutations have been identified in breast and endometrial cancers, our finding may open a path towards the therapy of these tumours.


Assuntos
ATPases Associadas a Diversas Atividades Celulares/genética , Antineoplásicos/farmacologia , Dano ao DNA , Proteínas de Ligação a DNA/genética , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , ATPases Associadas a Diversas Atividades Celulares/metabolismo , Animais , Linhagem Celular , Linhagem Celular Tumoral , Galinhas , Cromatina/enzimologia , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Instabilidade Genômica , Mutagênicos/toxicidade , Ftalazinas/farmacologia , Piperazinas/farmacologia , Poli(ADP-Ribose) Polimerase-1/metabolismo
19.
Mutat Res ; 850-851: 503133, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32247551

RESUMO

The "Micronuclei and Disease" workshop was organized by the HUMN Project consortium and hosted by the European Environmental Mutagen and Genomics Society at their annual meeting in Rennes, France, on 23 May 2019. The program of the workshop focused on addressing the emerging evidence linking micronucleus (MN) frequency to human disease. The first objective was to review what has been published and evaluate the level and quality of evidence for the connection between MN frequency and various diseases through all life stages. The second objective was to identify the knowledge gaps and what else needs to be done to determine the clinical utility of MN assays as predictors of disease risk and of prognosis when disease is active. Speakers at the workshop discussed the association of MN frequency with inflammation, infertility, pregnancy complications, obesity, diabetes, cardiovascular disease, kidney disease, cervical and bladder cancer, oral head and neck cancer, lung cancer, accelerated ageing syndromes, neurodegenerative diseases, and a road-map on how to utilise this knowledge was proposed. The outcomes of the workshop indicated that there are significant opportunities for translating the application of MN assays into clinical practice to improve disease prevention and risk management and to inform public health policy.


Assuntos
Dano ao DNA/efeitos dos fármacos , Metagenômica , Micronúcleos com Defeito Cromossômico/efeitos dos fármacos , Mutagênicos/toxicidade , Humanos , Testes para Micronúcleos
20.
Mutat Res ; 850-851: 503135, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32247552

RESUMO

Use of three-dimensional (3D) tissue equivalents in toxicology has been increasing over the last decade as novel preclinical test systems and as alternatives to animal testing. In the area of genetic toxicology, progress has been made with establishing robust protocols for skin, airway (lung) and liver tissue equivalents. In light of these advancements, a "Use of 3D Tissues in Genotoxicity Testing" working group (WG) met at the 7th IWGT meeting in Tokyo in November 2017 to discuss progress with these models and how they may fit into a genotoxicity testing strategy. The workshop demonstrated that skin models have reached an advanced state of validation following over 10 years of development, while liver and airway model-based genotoxicity assays show promise but are at an early stage of development. Further effort in liver and airway model-based assays is needed to address the lack of coverage of the three main endpoints of genotoxicity (mutagenicity, clastogenicity and aneugenicity), and information on metabolic competence. The IWGT WG believes that the 3D skin comet and micronucleus assays are now sufficiently validated to undergo an independent peer review of the validation study, followed by development of individual OECD Test Guidelines.


Assuntos
Dano ao DNA/efeitos dos fármacos , Metagenômica/tendências , Testes de Mutagenicidade/métodos , Mutagênicos/toxicidade , Dano ao DNA/genética , Humanos , Fígado/efeitos dos fármacos , Fígado/patologia , Testes para Micronúcleos
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