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1.
Gut Microbes ; 10(4): 458-480, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30580660

RESUMO

Probiotics are considered to have multiple beneficial effects on the human gastrointestinal tract, including immunomodulation, pathogen inhibition, and improved host nutrient metabolism. However, extensive characterization of these properties is needed to define suitable clinical applications for probiotic candidates. Lactobacillus johnsonii 456 (LBJ 456) was previously demonstrated to have anti-inflammatory and anti-genotoxic effects in a mouse model. Here, we characterize its resistance to gastric and bile acids as well as its ability to inhibit gut pathogens and adhere to host mucosa. While bile resistance and in vitro host attachment properties of LBJ 456 were comparable to other tested probiotics, LBJ 456 maintained higher viability at lower pH conditions compared to other tested strains. LBJ 456 also altered pathogen adhesion to LS 174T monolayers and demonstrated contact-dependent and independent inhibition of pathogen growth. Genome analyses further revealed possible genetic elements involved in host attachment and pathogen inhibition. Importantly, we show that ingestion of Lactobacillus johnsonii 456 over a one week yogurt course leads to persistent viable bacteria detectable even beyond the period of initial ingestion, unlike many other previously described probiotic species of lactic acid bacteria.

2.
Arch Toxicol ; 92(11): 3441, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30267108

RESUMO

The original article can be found online.

3.
Carcinogenesis ; 39(10): 1207-1215, 2018 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-30060078

RESUMO

Since its initial sales in the 1970s, the herbicide glyphosate attained widespread use in modern agriculture, becoming the most commercially successful and widely used herbicide of all time as of 2016. Despite a primary mechanism that targets a pathway absent from animal cells and regulatory studies showing safety margins orders of magnitude better than many other, more directly toxic herbicides, the safety status of glyphosate has recently been brought into question by a slow accumulation of studies suggesting more subtle health risks, especially when considered in combination with the surfactants it is usually applied with. Current, official views of respected international regulatory and health bodies remain divided on glyphosate's status as a human carcinogen, but the 2015 International Agency for Research on Cancer decision to reclassify the compound as Category 2A (probably carcinogenic to humans) marked a sea change in the scientific community's consensus view. The goal of this review is to consider the state of science regarding glyphosate's potential as a human carcinogen and genotoxin, with particular focus on studies suggesting mechanisms that would go largely undetected in traditional toxicology studies, such as microbiome disruption and endocrine mimicry at very low concentrations.

4.
Nutrients ; 9(12)2017 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-29231856

RESUMO

Resveratrol is a naturally occurring polyphenolic compound with various pharmacological activities. It is unknown whether the expression of metabolizing enzymes correlates with resveratrol levels in organs and tissues. Therefore, we investigated the metabolism and tissue distribution of resveratrol in mice and assessed its association with the expression of UDP-glucuronosyltransferase (Ugt) and sulfotransferase (Sult) genes. Plasma, urine, feces, and various organs were analyzed using high-performance liquid chromatography at up to 8 h after intragastric resveratrol administration. The metabolism of resveratrol was pronounced, leading to the formation of resveratrol glucuronides and sulfates. Concentrations of resveratrol and its metabolites were high in the gastrointestinal organs, urine, and feces, but low in the liver and kidneys. In lung, heart, thymus, and brain tissues, parent resveratrol levels exceeded the sulfate and glucuronide concentrations. The formation of resveratrol conjugates correlated with the expression of certain Ugt and Sult genes. Reverse transcription quantitative PCR (RT-qPCR) analysis revealed high mRNA expression of Ugt1a1 and Ugt1a6a in the liver, duodenum, jejunum, ileum, and colon, leading to high concentrations of resveratrol-3-O-glucuronide in these organs. Strong correlations of resveratrol-3-O-sulfate and resveratrol-3-O-4'-O-disulfate formation with Sult1a1 mRNA expression were also observed, particularly in the liver and colon. In summary, our data revealed organ-specific expression of Sults and Ugts in mice that strongly affects resveratrol concentrations; this may also be predictive in humans following oral uptake of dietary resveratrol.


Assuntos
Glucuronídeos/síntese química , Glucuronosiltransferase/metabolismo , Estilbenos/síntese química , Estilbenos/farmacocinética , Sulfotransferases/metabolismo , Animais , Camundongos , Resveratrol , Distribuição Tecidual
5.
Nat Commun ; 7: 12376, 2016 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-27507714

RESUMO

DNA double strand break (DSB) repair is critical for generation of B-cell receptors, which are pre-requisite for B-cell progenitor survival. However, the transcription factors that promote DSB repair in B cells are not known. Here we show that MEF2C enhances the expression of DNA repair and recombination factors in B-cell progenitors, promoting DSB repair, V(D)J recombination and cell survival. Although Mef2c-deficient mice maintain relatively intact peripheral B-lymphoid cellularity during homeostasis, they exhibit poor B-lymphoid recovery after sub-lethal irradiation and 5-fluorouracil injection. MEF2C binds active regulatory regions with high-chromatin accessibility in DNA repair and V(D)J genes in both mouse B-cell progenitors and human B lymphoblasts. Loss of Mef2c in pre-B cells reduces chromatin accessibility in multiple regulatory regions of the MEF2C-activated genes. MEF2C therefore protects B lymphopoiesis during stress by ensuring proper expression of genes that encode DNA repair and B-cell factors.


Assuntos
Quebras de DNA de Cadeia Dupla , Hematopoese/fisiologia , Células Precursoras de Linfócitos B/fisiologia , Recombinação V(D)J/fisiologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Sobrevivência Celular/efeitos da radiação , Cromatina/metabolismo , Feminino , Fluoruracila/farmacologia , Hematopoese/efeitos dos fármacos , Hematopoese/efeitos da radiação , Fatores de Transcrição MEF2/fisiologia , Masculino , Camundongos , Células Precursoras de Linfócitos B/efeitos dos fármacos , Células Precursoras de Linfócitos B/efeitos da radiação , Irradiação Corporal Total/efeitos adversos
6.
Arch Toxicol ; 90(9): 2109-2130, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27311821

RESUMO

Chronic inflammation is strongly associated with approximately one-fifth of all human cancers. Arising from combinations of factors such as environmental exposures, diet, inherited gene polymorphisms, infections, or from dysfunctions of the immune response, chronic inflammation begins as an attempt of the body to remove injurious stimuli; however, over time, this results in continuous tissue destruction and promotion and maintenance of carcinogenesis. Here, we focus on intestinal inflammation and its associated cancers, a group of diseases on the rise and affecting millions of people worldwide. Intestinal inflammation can be widely grouped into inflammatory bowel diseases (ulcerative colitis and Crohn's disease) and celiac disease. Long-standing intestinal inflammation is associated with colorectal cancer and small-bowel adenocarcinoma, as well as extraintestinal manifestations, including lymphomas and autoimmune diseases. This article highlights potential mechanisms of pathogenesis in inflammatory bowel diseases and celiac disease, as well as those involved in the progression to associated cancers, most of which have been identified from studies utilizing mouse models of intestinal inflammation. Mouse models of intestinal inflammation can be widely grouped into chemically induced models; genetic models, which make up the bulk of the studied models; adoptive transfer models; and spontaneous models. Studies in these models have lead to the understanding that persistent antigen exposure in the intestinal lumen, in combination with loss of epithelial barrier function, and dysfunction and dysregulation of the innate and adaptive immune responses lead to chronic intestinal inflammation. Transcriptional changes in this environment leading to cell survival, hyperplasia, promotion of angiogenesis, persistent DNA damage, or insufficient repair of DNA damage due to an excess of proinflammatory mediators are then thought to lead to sustained malignant transformation. With regard to extraintestinal manifestations such as lymphoma, however, more suitable models are required to further investigate the complex and heterogeneous mechanisms that may be at play.


Assuntos
Doença Celíaca/complicações , Transformação Celular Neoplásica , Colite Ulcerativa/complicações , Doença de Crohn/complicações , Neoplasias Intestinais/etiologia , Animais , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Doença Celíaca/genética , Doença Celíaca/metabolismo , Doença Celíaca/patologia , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Colite Ulcerativa/genética , Colite Ulcerativa/metabolismo , Colite Ulcerativa/patologia , Doença de Crohn/genética , Doença de Crohn/metabolismo , Doença de Crohn/patologia , Dano ao DNA , Modelos Animais de Doenças , Regulação Neoplásica da Expressão Gênica , Humanos , Mediadores da Inflamação/metabolismo , Neoplasias Intestinais/genética , Neoplasias Intestinais/metabolismo , Neoplasias Intestinais/patologia , Camundongos , Fatores de Risco , Transdução de Sinais , Microambiente Tumoral
7.
Mutagenesis ; 31(5): 491-509, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27209205

RESUMO

Potential ionising radiation exposure scenarios are varied, but all bring risks beyond the simple issues of short-term survival. Whether accidentally exposed to a single, whole-body dose in an act of terrorism or purposefully exposed to fractionated doses as part of a therapeutic regimen, radiation exposure carries the consequence of elevated cancer risk. The long-term impact of both intentional and unintentional exposure could potentially be mitigated by treatments specifically developed to limit the mutations and precancerous replication that ensue in the wake of irradiation The development of such agents would undoubtedly require a substantial degree of in vitro testing, but in order to accurately recapitulate the complex process of radiation-induced carcinogenesis, well-understood animal models are necessary. Inbred strains of the laboratory mouse, Mus musculus, present the most logical choice due to the high number of molecular and physiological similarities they share with humans. Their small size, high rate of breeding and fully sequenced genome further increase its value for use in cancer research. This chapter will review relevant m. musculus inbred and F1 hybrid animals of radiation-induced myeloid leukemia, thymic lymphoma, breast and lung cancers. Method of cancer induction and associated molecular pathologies will also be described for each model.


Assuntos
Modelos Animais de Doenças , Camundongos , Neoplasias Induzidas por Radiação , Animais , Feminino , Masculino , Neoplasias Induzidas por Radiação/genética
8.
PLoS One ; 11(4): e0151190, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27073845

RESUMO

Intestinal microbiota play a significant role in nutrient metabolism, modulation of the immune system, obesity, and possibly in carcinogenesis, although the underlying mechanisms resulting in disease or impacts on longevity caused by different intestinal microbiota are mostly unknown. Herein we use isogenic Atm-deficient and wild type mice as models to interrogate changes in the metabolic profiles of urine and feces of these mice, which are differing in their intestinal microbiota. Using high resolution mass spectrometry approach we show that the composition of intestinal microbiota modulates specific metabolic perturbations resulting in a possible alleviation of a glycolytic phenotype. Metabolites including 3-methylbutyrolactone, kyneurenic acid and 3-methyladenine known to be onco-protective are elevated in Atm-deficient and wild type mice with restricted intestinal microbiota. Thus our approach has broad applicability to study the direct influence of gut microbiome on host metabolism and resultant phenotype. These results for the first time suggest a possible correlation of metabolic alterations and carcinogenesis, modulated by intestinal microbiota in A-T mice.


Assuntos
4-Butirolactona/análogos & derivados , Adenina/análogos & derivados , Transformação Celular Neoplásica , Microbioma Gastrointestinal , Neoplasias Intestinais , 4-Butirolactona/metabolismo , Adenina/metabolismo , Animais , Camundongos , Camundongos Knockout
9.
Mutagenesis ; 30(6): 841-9, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26122113

RESUMO

Non-homologous end joining (NHEJ) directly joins two broken DNA ends without sequence homology. A distinct pathway called microhomology-mediated end joining (MMEJ) relies on a few base pairs of homology between the recombined DNA. The majority of DNA double-strand breaks caused by endogenous oxygen species or ionizing radiation contain damaged bases that hinder direct religation. End processing is required to remove mismatched nucleotides and fill in gaps during end joining of incompatible ends. POL3 in Saccharomyces cerevisiae encodes polymerase δ that is required for DNA replication and other DNA repair processes. Our previous results have shown that POL3 is involved in gap filling at 3' overhangs in POL4-independent NHEJ. Here, we studied the epistatic interaction between POL3, RAD50, XRS2 and POL4 in NHEJ using a plasmid-based endjoining assay in yeast. We demonstrated that either rad50 or xrs2 mutation is epistatic for end joining of compatible ends in the rad50 pol3-t or xrs2 pol3-t double mutants. However, the pol3-t and rad50 or pol3-t and xrs2 mutants caused an additive decrease in the end-joining efficiency of incompatible ends, suggesting that POL3 and RAD50 or POL3 and XRS2 exhibit independent functions in NHEJ. In the rad50 pol4 mutant, end joining of incompatible ends was not detected. In the rad50 or xrs2 mutants, NHEJ events did not contain any microhomology at the rejoined junctions. The pol3-t mutation restored MMEJ in the rad50 or xrs2 mutant backgrounds. Moreover, we demonstrated that NHEJ of incompatible ends required RAD50 and POL4 more than POL3. In conclusion, POL3 and POL4 have differential functions in NHEJ, independent of the RAD50-mediated repair pathway.


Assuntos
Reparo do DNA por Junção de Extremidades , DNA Polimerase III/metabolismo , DNA Polimerase beta/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , DNA Polimerase III/genética , DNA Polimerase beta/genética , Reparo do DNA , Proteínas de Ligação a DNA/metabolismo , Mutação
10.
Radiat Res ; 183(6): 589-93, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26010710

RESUMO

Intestinal microbiota affect cell responses to ionizing radiation at the molecular level and can be linked to the development of the immune system, controlled cell death or apoptosis. We have developed a microbiota mouse model and report here that high-linear energy transfer (LET) radiation induced the repair of chromosomal DNA lesions more efficiently in conventional than in restricted intestinal microbiota mice. Based on different phylotype densities after whole-body irradiation, bacterial indicator phylotypes were found to be more abundant in restricted in microbiota than in conventional microbiota. Genotoxic phenotypes of irradiated restricted and conventional microbiota mice were compared with ataxia telangiectasia-deficient restricted and conventional microbiota mice, respectively. Those indicator phylotypes, including Bacteroides (Gram-negative bacterium cTPY-13), Barnesiella intestinihominis and others, which were identified in nonirradiated restricted microbiota mice, increase in radiation-exposed conventional microbiota along with a reduction of persistent DNA double-strand breaks in blood lymphocytes. The dynamic change of phylotype abundances elucidated a feedback mechanism and effect of intestinal microbiota composition on the adaptive response to high-LET radiation. Several other bacterial phylotypes ( Helicobacter hepaticus , Helicobacter spp and others) were found to be more abundant in conventional than restricted microbiota. In this commentary, mouse models used in cancer research and radiotherapy for the study on the effects of intestinal microbiota composition on normal tissue radiation response are characterized and discussed. Highlights of this commentary: 1. Restricted microbiota phylotypes were correlated with persistent DNA double-strand breaks (DSBs) and were found to orchestrate onco-protective controlled cell death after radiation; 2. Restricted microbiota composition reduced proinflammatory extracellular-stimulated immune responses, but specifically increased anti-neoplastic cytolytic memory CD8(+) T cells by low taxonomic diversity and 3. DNA damage repair efficiency induced by a model of conventional microbiota most likely initiates an adaptive response to radiation through microbiota-induced intestinal sub-symptomatic inflammation.


Assuntos
Intestinos/microbiologia , Intestinos/efeitos da radiação , Transferência Linear de Energia , Microbiota/efeitos da radiação , Lesões por Radiação/microbiologia , Animais , Biomarcadores , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/efeitos da radiação , Ciclo Celular/efeitos da radiação , Quebras de DNA de Cadeia Dupla/efeitos da radiação , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Células Endoteliais/microbiologia , Células Endoteliais/efeitos da radiação , Homeostase/efeitos da radiação , Intestinos/imunologia , Camundongos , Modelos Animais , Fenótipo , Lesões por Radiação/imunologia , Risco
11.
Mutat Res ; 769: 100-7, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25400503

RESUMO

Asthma is a common heterogeneous disease with both genetic and environmental factors that affects millions of individuals worldwide. Activated type 2 helper T cells secrete a panel of cytokines, including IL-13, a central immune regulator of many of the hallmark type 2 disease characteristics found in asthma. IL-13 has been directly implicated as a potent stimulator of asthma induced airway remodeling. Although IL-13 is known to play a major role in the development and persistence of asthma, the complex combination of environmental and genetic origin of the disease obfuscate the solitary role of IL-13 in the disease. We therefore, used a genetically modified mouse model which conditionally overexpresses IL-13 in the lungs to study the independent role of IL-13 in the progression of asthma. Our results demonstrate IL-13 is associated with a systemic induction of genotoxic parameters such as oxidative DNA damage, single and double DNA strand breaks, micronucleus formation, and protein nitration. Furthermore we show that inflammation induced genotoxicity found in asthma extends beyond the primary site of the lung to circulating leukocytes and erythroblasts in the bone marrow eliciting systemic effects driven by IL-13 over-expression.


Assuntos
Dano ao DNA/genética , Inflamação/genética , Interleucina-13/genética , Leucócitos/metabolismo , Pulmão/metabolismo , Animais , Asma/genética , Asma/imunologia , Asma/patologia , Modelos Animais de Doenças , Inflamação/imunologia , Inflamação/metabolismo , Interleucina-13/metabolismo , Leucócitos/imunologia , Camundongos , Camundongos Transgênicos , Células Th2/imunologia , Células Th2/metabolismo , Regulação para Cima/genética
12.
Int J Environ Res Public Health ; 11(9): 9038-49, 2014 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-25257357

RESUMO

The intestinal microbiota and gut immune system must constantly communicate to maintain a balance between tolerance and activation: on the one hand, our immune system should protect us from pathogenic microbes and on the other hand, most of the millions of microbes in and on our body are innocuous symbionts and some can even be beneficial. Since there is such a close interaction between the immune system and the intestinal microbiota, it is not surprising that some lymphomas such as mucosal-associated lymphoid tissue (MALT) lymphoma have been shown to be caused by the presence of certain bacteria. Animal models played an important role in establishing causation and mechanism of bacteria-induced MALT lymphoma. In this review we discuss different ways that animal models have been applied to establish a link between the gut microbiota and lymphoma and how animal models have helped to elucidate mechanisms of microbiota-induced lymphoma. While there are not a plethora of studies demonstrating a connection between microbiota and lymphoma development, we believe that animal models are a system which can be exploited in the future to enhance our understanding of causation and improve prognosis and treatment of lymphoma.


Assuntos
Intestinos/microbiologia , Linfoma/microbiologia , Microbiota , Animais , Fenômenos Fisiológicos Bacterianos , Modelos Animais de Doenças , Humanos
13.
Hum Genomics ; 8: 13, 2014 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-25062865

RESUMO

The use of radiation therapy is a cornerstone of modern cancer treatment. The number of patients that undergo radiation as a part of their therapy regimen is only increasing every year, but this does not come without cost. As this number increases, so too does the incidence of secondary, radiation-induced neoplasias, creating a need for therapeutic agents targeted specifically towards incidence reduction and treatment of these cancers. Development and efficacy testing of these agents requires not only extensive in vitro testing but also a set of reliable animal models to accurately recreate the complex situations of radiation-induced carcinogenesis. As radiation-induced leukemic progression often involves genomic changes such as rearrangements, deletions, and changes in methylation, the laboratory mouse Mus musculus, with its fully sequenced genome, is a powerful tool in cancer research. This fact, combined with the molecular and physiological similarities it shares with man and its small size and high rate of breeding in captivity, makes it the most relevant model to use in radiation-induced leukemia research. In this work, we review relevant M. musculus inbred and F1 hybrid animal models, as well as methods of induction of radiation-induced myeloid leukemia. Associated molecular pathologies are also included.


Assuntos
Leucemia Mieloide/genética , Lesões Experimentais por Radiação/genética , Animais , Carcinogênese/genética , Carcinogênese/efeitos da radiação , Humanos , Leucemia Mieloide/patologia , Camundongos , Camundongos Endogâmicos , Camundongos Transgênicos , Lesões Experimentais por Radiação/patologia , Tolerância a Radiação
14.
Cancer J ; 20(3): 190-4, 2014 May-Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24855006

RESUMO

The intestinal microbiota and gut immune system must communicate to maintain a balance between tolerance and activation. Our immune system protects us from pathogenic microbes at the same time that our bodies are host to trillions of microbes, symbionts, mutualists, and some that are essential to human health. Since there is such a close interaction between the immune system and the intestinal microbiota, it is not surprising that some lymphomas such as mucosal-associated lymphoid tissue lymphoma have been shown to be caused by the presence of certain bacteria. Animal models have played an important role in elucidating the causation and establishing the mechanism of bacteria-induced mucosal-associated lymphoid tissue lymphoma. In this review, we discuss different ways that animal models have been applied to investigate links between the gut microbiota and lymphoma and have helped to reveal the mechanisms of microbiota-induced lymphoma. Although there is a paucity of published studies demonstrating the interplay between the microbiota and lymphoma development, we believe that the connection is real and that it can be exploited in the future to enhance our understanding of causation and to improve the prognosis and treatment of lymphoma.


Assuntos
Intestinos/microbiologia , Linfoma/microbiologia , Microbiota , Animais , Modelos Animais de Doenças , Humanos
15.
Radiat Res ; 181(1): 45-53, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24397477

RESUMO

Ionizing space radiation causes oxidative DNA damage and triggers oxidative stress responses, and compromised DNA repair mechanisms can lead to increased risk of carcinogenesis. Young adult mice with developed innate and adaptive immune systems that harbored either a conventional intestinal microbiota (CM) or an intestinal microbiota with a restricted microbial composition (RM) were irradiated with a total dose of 1 Gy delivered by high-energy protons (2.5 GeV/n, LET = 0.2-2 keV/µm) or silicon or iron ions (850 MeV/n, LET ≈ 50 keV/µm and 1 GeV/n, LET = 150 keV/µm, respectively). Six hours after whole-body irradiation, acute chromosomal DNA lesions were observed for RM mice but not CM mice. High-throughput rRNA gene sequencing of intestinal mucosal bacteria showed that Barnesiella intestinihominis and unclassified Bacterodiales were significantly more abundant in male RM mice than CM mice, and phylotype densities changed in irradiated mice. In addition, Helicobacter hepaticus and Bacteroides stercoris were higher in CM than RM mice. Elevated levels of persistently phosphorylated γ-H2AX were observed in RM mice exposed to high-energy protons compared to nonirradiated RM mice, and they also were associated with a decrease of the antioxidant glutathione in peripheral blood measured at four weeks after irradiation. After radiation exposure, CM mice showed lower levels of γ-H2AX phosphorylation than RM mice and an increase in specific RM-associated phylotypes, indicating a down-regulating force on DNA repair by differentially abundant phylotypes in RM versus a radiation-sensitive complex CM.


Assuntos
Determinação de Ponto Final , Intestinos/microbiologia , Microbiota/efeitos da radiação , Prótons/efeitos adversos , Animais , Aberrações Cromossômicas/efeitos da radiação , Quebras de DNA de Cadeia Dupla/efeitos da radiação , Meio Ambiente Extraterreno , Fezes/microbiologia , Feminino , Transferência Linear de Energia/efeitos da radiação , Masculino , Camundongos , Testes de Mutagenicidade , Estresse Oxidativo/efeitos da radiação , Linfócitos T/metabolismo , Linfócitos T/efeitos da radiação
16.
Cancer Res ; 73(14): 4222-32, 2013 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-23860718

RESUMO

Ataxia-telangiectasia is a genetic disorder associated with high incidence of B-cell lymphoma. Using an ataxia-telangiectasia mouse model, we compared lymphoma incidence in several isogenic mouse colonies harboring different bacterial communities, finding that intestinal microbiota are a major contributor to disease penetrance and latency, lifespan, molecular oxidative stress, and systemic leukocyte genotoxicity. High-throughput sequence analysis of rRNA genes identified mucosa-associated bacterial phylotypes that were colony-specific. Lactobacillus johnsonii, which was deficient in the more cancer-prone mouse colony, was causally tested for its capacity to confer reduced genotoxicity when restored by short-term oral transfer. This intervention decreased systemic genotoxicity, a response associated with reduced basal leukocytes and the cytokine-mediated inflammatory state, and mechanistically linked to the host cell biology of systemic genotoxicity. Our results suggest that intestinal microbiota are a potentially modifiable trait for translational intervention in individuals at risk for B-cell lymphoma, or for other diseases that are driven by genotoxicity or the molecular response to oxidative stress.


Assuntos
Inflamação/microbiologia , Intestinos/microbiologia , Lactobacillus/fisiologia , Leucócitos/microbiologia , Linfoma de Células B/metabolismo , Linfoma de Células B/microbiologia , Animais , Ataxia Telangiectasia/complicações , Instabilidade Genômica , Incidência , Linfoma de Células B/genética , Masculino , Camundongos , Camundongos Transgênicos , Microbiota , Estresse Oxidativo/fisiologia
17.
Mutat Res ; 749(1-2): 58-65, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23748015

RESUMO

Cigarette smoke causes direct oxidative DNA damage as well as indirect damage through inflammation. Epidemiological studies show a strong relationship between secondhand smoke and cancer; however, the mechanisms of secondhand smoke-induced cancer are not well understood. Animal models with either (i) deficient oxidative DNA damage repair, or (ii) a decreased capacity to combat oxidative stress may help determine the pathways important in mitigating damage caused by smoke. In this study, we used mice lacking Ogg1 and Myh, both of which are involved in base excision repair by removing oxidatively damaged DNA bases. Gclm-deficient mice, which have decreased levels of glutathione (GSH), were used to look at the role of smoke-induced oxidative damage. Ex vivo experiments show significantly elevated levels of DNA single-strand breaks and chromosomal aberrations in peripheral blood lymphocytes from Ogg1(-/-)Myh(-/-) double knockout mice compared to wild type (WT) mice after 24h of exposure to cigarette smoke extract (CSE). The average γH2AX foci per cell was significantly elevated 3h after exposure to CSE in cells from Ogg1(-/-)Myh(-/-) double knockout mice compared to wildtype mice. In vivo we found that all mice had increased markers of DNA damage after exposure to side-stream tobacco smoke (SSTS). Ogg1(-/-)Myh(-/-) and Gclm(-/-) mice had altered levels of peripheral blood glutathione after SSTS exposure whereas wild type mice did not. This may be due to differential regulation of glutathione synthesis in the lung. We also found that Ogg1(-/-)Myh(-/-) mice had a decreased lifespan after oral gavage with benzo[a]pyrene compared to wildtype mice and sham-exposed Ogg1(-/-)Myh(-/-) mice. Our results are important in investigating the roles of oxidative stress and oxidative DNA damage repair in cigarette smoke-induced cancers and characterizing the role of genetic polymorphisms in smoke-related disease susceptibility.


Assuntos
Células Sanguíneas/efeitos dos fármacos , Distúrbios no Reparo do DNA/genética , Glutationa/deficiência , Estresse Oxidativo/genética , Poluição por Fumaça de Tabaco/efeitos adversos , Animais , Células Sanguíneas/metabolismo , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , DNA Glicosilases/genética , Distúrbios no Reparo do DNA/sangue , Distúrbios no Reparo do DNA/patologia , Feminino , Glutamato-Cisteína Ligase/genética , Glutationa/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Estresse Oxidativo/efeitos dos fármacos
18.
PLoS One ; 7(9): e44700, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22970289

RESUMO

The pesticide rotenone, a neurotoxin that inhibits the mitochondrial complex I, and destabilizes microtubules (MT) has been linked to Parkinson disease (PD) etiology and is often used to model this neurodegenerative disease (ND). Many of the mechanisms of action of rotenone are posited mechanisms of neurodegeneration; however, they are not fully understood. Therefore, the study of rotenone-affected functional pathways is pertinent to the understanding of NDs pathogenesis. This report describes the transcriptome analysis of a neuroblastoma (NB) cell line chronically exposed to marginally toxic and moderately toxic doses of rotenone. The results revealed a complex pleiotropic response to rotenone that impacts a variety of cellular events, including cell cycle, DNA damage response, proliferation, differentiation, senescence and cell death, which could lead to survival or neurodegeneration depending on the dose and time of exposure and cell phenotype. The response encompasses an array of physiological pathways, modulated by transcriptional and epigenetic regulatory networks, likely activated by homeostatic alterations. Pathways that incorporate the contribution of MT destabilization to rotenone toxicity are suggested to explain complex I-independent rotenone-induced alterations of metabolism and redox homeostasis. The postulated mechanisms involve the blockage of mitochondrial voltage-dependent anions channels (VDACs) by tubulin, which coupled with other rotenone-induced organelle dysfunctions may underlie many presumed neurodegeneration mechanisms associated with pathophysiological aspects of various NDs including PD, AD and their variant forms. Thus, further investigation of such pathways may help identify novel therapeutic paths for these NDs.


Assuntos
Modelos Biológicos , Doenças Neurodegenerativas/induzido quimicamente , Transtornos Parkinsonianos/induzido quimicamente , Rotenona/farmacologia , Transcriptoma , Potenciais de Ação , Linhagem Celular , Humanos , Doenças Neurodegenerativas/patologia , Análise de Sequência com Séries de Oligonucleotídeos , Transtornos Parkinsonianos/patologia , Rotenona/toxicidade
19.
Environ Mol Mutagen ; 53(2): 94-100, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22020802

RESUMO

Cr(VI) is a human and animal carcinogen. Cr(VI) does not interact directly with DNA and thus its genotoxicity is attributed to its intracellular reduction to Cr(III) via reactive intermediates. The resulting types of DNA damage can be grouped into two categories: (1) oxidative DNA damage and (2) Cr(III)-DNA interactions. This study examines the molecular mechanism of Cr(VI) and Cr(III) genotoxicity in an intact cell. A system screening for DNA deletions (DEL assay) was used to compare induction of chromosomal rearrangements in the yeast Saccharomyces cerevisiae following Cr(VI) and Cr(III) exposure. Both forms of chromium induced DNA deletions albeit with different dose-response curves. N-acetylcysteine had a protective effect against Cr(VI) genotoxicity at high exposure doses but had no protective effect at lower doses or against Cr(III). An oxidative DNA damage repair mutant was hypersensitive to Cr(VI) only at high exposure and the mutant was not hypersensitive to Cr(III) exposure. These data imply that oxidative stress is involved in Cr(VI) genotoxicity at high exposure concentrations and not so in Cr(III). The Cr(III)-DNA interaction appears to be an important genotoxic lesion following Cr(VI) exposure at low-exposure concentrations. The CAN forward mutation assay revealed that within the concentration ranges used for this study, Cr(III) does not cause point mutations and Cr(VI) causes a mild but statistically significant increase in point mutation only at the highest concentration tested. This study reveals that DNA deletions occurring as a result of intrachromosomal homologous recombination are a useful endpoint for studying chromium genotoxicity.


Assuntos
Carcinógenos Ambientais/toxicidade , Cromo/toxicidade , Dano ao DNA/efeitos dos fármacos , Acetilcisteína/farmacologia , Animais , Carcinógenos Ambientais/metabolismo , Linhagem Celular , Cromo/metabolismo , Reparo do DNA/efeitos dos fármacos , Depuradores de Radicais Livres/farmacologia , Recombinação Homóloga , Taxa de Mutação , Oxirredução , Ratos
20.
Exp Hematol ; 40(1): 3-13.e3, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22001673

RESUMO

Purine analogs such as 6-thioguanine (6TG) cause myelotoxicity upon conversion into nucleotides by hypoxanthine-guanine phosphoribosyltransferase (HPRT). Here we have developed a novel and highly efficient strategy employing 6TG as a single agent for both conditioning and in vivo chemoselection of HPRT-deficient hematopoietic stem cells. The dose-response and time course of 6TG myelotoxicity were first compared in HPRT wild-type mice and HPRT-deficient transgenic mice. Dosage and schedule parameters were optimized to employ 6TG for myelosuppressive conditioning, immediately followed by in vivo chemoselection of HPRT-deficient transgenic donor bone marrow (BM) transplanted into syngeneic HPRT wild-type recipients. At appropriate doses, 6TG induced selective myelotoxicity without any adverse effects on extrahematopoietic tissues in HPRT wild-type mice, while hematopoietic stem cells deficient in HPRT activity were highly resistant to its cytotoxic effects. Combined 6TG conditioning and post-transplantation chemoselection consistently achieved ∼95% engraftment of HPRT-deficient donor BM, with low overall toxicity. Long-term reconstitution of immunophenotypically normal BM was achieved in both primary and secondary recipients. Our results provide proof-of-concept that single-agent 6TG can be used for both myelosuppressive conditioning without requiring irradiation and for in vivo chemoselection of HPRT-deficient donor cells. Our results show that by applying the myelosuppressive effects of 6TG both before (as conditioning) and after transplantation (as chemoselection), highly efficient engraftment of HPRT-deficient hematopoietic stem cells can be achieved.


Assuntos
Transplante de Medula Óssea , Medula Óssea/efeitos dos fármacos , Hematopoese/efeitos dos fármacos , Hipoxantina Fosforribosiltransferase/deficiência , Tioguanina/farmacologia , Condicionamento Pré-Transplante , Animais , Medula Óssea/enzimologia , Relação Dose-Resposta a Droga , Células-Tronco Hematopoéticas/metabolismo , Hipoxantina Fosforribosiltransferase/metabolismo , Injeções Intraperitoneais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Tioguanina/administração & dosagem , Tioguanina/efeitos adversos , Fatores de Tempo
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