Folate and vitamin B12 related to homocysteine and DNA damage in female university students / Folato e vitamina B12 relacionados com homocisteína e danos no DNA em estudantes universitárias / Folato y vitamina B12 relacionados con homocisteína y daño en el ADN en estudiantes universitarias

Background and Objectives: It is not clear whether the increase in nutrition students' knowledge is associated with healthier eating behavior and fewer micronutrient deficiencies that can cause DNA damage. Deficiency in some vitamins can be a risk factor for increased homocysteine (Hcy) levels, a marker of cardiovascular risk. Therefore, this study aimed to verify whether dietary and serum folate and vitamin B12 are associated with Hcy levels and DNA damage in female university students. Methods: A cross-sectional study was conducted with female university students from southern Brazil. Folate, vitamin B12, and Hcy levels were determined in their diet or serum. DNA damage levels were assessed by the alkaline comet assay (index and frequency) and the buccal micronucleus assay (micronuclei frequency and binucleated cells frequency). Results: Correlation analyses did not show an association between Hcy levels and dietary or serum folate and vitamin B12 consumption. Dietary folate and vitamin B12 were associated with the index and frequency of damages; however, only serum folate was negatively associated with the index and frequency of damages. Additionally, the frequency of binucleated cells was negatively associated with dietary vitamin B12 and positively associated with serum levels. Serum folate was negatively associated with the frequency of micronuclei. Hcy levels were associated with the index and frequency of damages. Conclusion: These findings strengthen the role of healthier dietary patterns with adequate micronutrients as a preventive strategy to reduce the risk of cardiovascular diseases. This approach should play a pivotal role in shaping health policies and advocating for appropriate food choices.(AU)

Justificativa e Objetivos: Não está claro se o aumento do conhecimento dos estudantes de nutrição está associado a um comportamento alimentar mais saudável, com menores deficiências de micronutrientes que podem induzir danos no DNA. A deficiência de algumas vitaminas pode ser um fator de risco para o aumento dos níveis de homocisteína (Hcy), um marcador de risco cardiovascular. Portanto, este estudo verificou se folato e vitamina B12 dietético e sérico estão associados aos níveis de Hcy e danos no DNA em estudantes universitárias. Métodos: Estudo transversal com universitárias do sul do Brasil. Determinou-se folato, vitamina B12 e Hcy dietético e séricos. Os níveis de danos no DNA foram avaliados pelo ensaio do cometa alcalino (índice e frequência) e pelo ensaio de micronúcleos bucais (frequência de micronúcleos e células binucleadas). Resultados: Análises de correlação não mostraram associação entre os níveis de Hcy com o consumo de folato e vitamina B12 dietético ou sérico. Folato e vitamina B12 dietéticos associou-se ao índice e frequência de danos, entretanto, somente folato sérico associou-se negativamente ao índice e frequência de danos. Ainda, a frequência de células binucleadas estava negativamente associada à vitamina B12 da dieta e positivamente associada aos níveis séricos. Folato sérico associou-se negativamente à frequência de micronúcleos. Os níveis de Hcy associou-se ao índice e frequência de danos. Conclusão: Esses achados fortalecem o papel de padrões alimentares mais saudáveis com micronutrientes adequados como estratégia preventiva visando a redução do risco de doenças cardiovasculares. Esta abordagem deve desempenhar um papel fundamental na formulação de políticas de saúde e na defesa de escolhas alimentares apropriadas.(AU)

Justificación y Objetivos: No está claro si el aumento del conocimiento de estudiantes de nutrición está asociado con un comportamiento alimentario más saludable, con menores deficiencias de micronutrientes que puedan inducir daños en ADN. La deficiencia de algunas vitaminas puede ser un factor de riesgo para el aumento de los niveles de homocisteína (Hcy), marcador de riesgo cardiovascular. Consiguiente, este estudio verificó si folato y vitamina B12 dietéticos y séricos están asociados con niveles de Hcy y daños en el ADN en estudiantes universitarias. Métodos: Estudio transversal con universitarias del sur de Brasil. Se determinaron folato, vitamina B12 y Hcy dietéticos y séricos. Los niveles de daño en el ADN se evaluaron por ensayo del cometa alcalino (índice y frecuencia) y el ensayo de micronúcleos bucales (frecuencia de micronúcleos y células binucleadas). Resultados: Los análisis de correlación no mostraron asociación entre los niveles de Hcy con folato y vitamina B12 dietéticos y séricos. Folato y vitamina B12 dietéticos se asociaron con índice y frecuencia de daños, pero, solo folato sérico se asoció negativamente con índice y frecuencia de daños. Además, la frecuencia de células binucleadas estaba negativamente asociada con la vitamina B12 de la dieta y positivamente asociada con los niveles séricos. Folato sérico se asoció negativamente con la frecuencia de micronúcleos. Los niveles de Hcy se asociaron con índice y frecuencia de daños. Conclusión: Estos hallazgos refuerzan el papel de patrones alimentarios más saludables con micronutrientes adecuados como estrategia preventiva para reducir el riesgo de enfermedades cardiovasculares. Este enfoque debería desempeñar un papel fundamental en la elaboración de políticas de salud y en la promoción de elecciones alimenticias apropiadas.(AU)

Research Advances of RAD51AP1 in Tumor Progression and Drug Resistance / 中国肺癌杂志

The genomic instability may lead to an initiation of cancer in many organisms. Homologous recombination repair (HRR) is vital in maintaining cellular genomic stability. RAD51 associated protein 1 (RAD51AP1), which plays a crucial role in HRR and primarily participates in forming D-loop, was reported as an essential protein for maintaining cellular genomic stability. However, recent studies showed that RAD51AP1 was significantly overexpressed in various cancer types and correlated with poor prognosis. These results suggested that RAD51AP1 may play a significant pro-cancer effect in multiple cancers. The underlying mechanism is still unclear. Cancer stemness-maintaining effects of RAD51AP1 might be considered as the most reliable mechanism. Meanwhile, RAD51AP1 also promoted resistance to radiation therapy and chemotherapy in many cancers. Thus, researches focused on RAD51AP1, and its regulatory molecules may provide new targets for overcoming cancer progression and treatment resistance. Here, we reviewed the latest research on RAD51AP1 in cancers and summarized its differential expression and prognostic implications. In this review, we also outlined the potential mechanisms of its pro-cancer and drug resistance-promoting effects to provide several potential directions for further research.
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Dual role of lipids for genome stability and pluripotency facilitates full potency of mouse embryonic stem cells

While Mek1/2 and Gsk3β inhibition ("2i") supports the maintenance of murine embryonic stem cells (ESCs) in a homogenous naïve state, prolonged culture in 2i results in aneuploidy and DNA hypomethylation that impairs developmental potential. Additionally, 2i fails to support derivation and culture of fully potent female ESCs. Here we find that mouse ESCs cultured in 2i/LIF supplemented with lipid-rich albumin (AlbuMAX) undergo pluripotency transition yet maintain genomic stability and full potency over long-term culture. Mechanistically, lipids in AlbuMAX impact intracellular metabolism including nucleotide biosynthesis, lipid biogenesis, and TCA cycle intermediates, with enhanced expression of DNMT3s that prevent DNA hypomethylation. Lipids induce a formative-like pluripotent state through direct stimulation of Erk2 phosphorylation, which also alleviates X chromosome loss in female ESCs. Importantly, both male and female "all-ESC" mice can be generated from de novo derived ESCs using AlbuMAX-based media. Our findings underscore the importance of lipids to pluripotency and link nutrient cues to genome integrity in early development.

Diagnóstico citogenético de la anemia de Fanconi en pacientes cubanos con sospecha clínica de la enfermedad / Cytogenetic diagnosis of Fanconi anemia in Cuban patients with clinical suspicion of the disease

Introducción: La anemia de Fanconi es una enfermedad genética rara, de herencia autosómica o ligada al X, caracterizada por inestabilidad genómica e hipersensibilidad a los agentes de entrecruzamiento del ADN, como el diepoxibutano y la mitomicina C (MMC). La respuesta anormal a estas sustancias, que constituye un marcador celular único y se manifiesta como un incremento de la frecuencia de roturas cromosómicas, es la base de su diagnóstico. Objetivo: Realizar el análisis de roturas cromosómicas inducidas por la mitomicina C en linfocitos de sangre periférica de pacientes cubanos con sospecha de anemia de Fanconi. Métodos: Se realizó estudio de roturas cromosómicas inducidas por la mitomicina C a diferentes concentraciones en cultivos de linfocitos T provenientes de sangre venosa periférica en 32 pacientes con sospecha clínica de anemia de Fanconi e igual cantidad de sujetos controles. Resultados: Al finalizar el análisis seis pacientes (20 por ciento) fueron diagnosticados con anemia de Fanconi. De ellos, cuatro presentaron alto porcentaje de rupturas y dos un mosaicismo somático. Desde el punto de vista clínico, cuatro mostraban anemia aplásica y dos exhibían únicamente rasgos dismórficos típicos de la enfermedad. Conclusiones: El ensayo de roturas cromosómicas inducidas por la mitomicina C permitió el diagnóstico definitivo de anemia de Fanconi en pacientes con antecedentes de anemia aplásica, aún sin anomalías congénitas. Este constituye el primer estudio de este tipo en un grupo de pacientes cubanos(AU)

Introduction: Fanconi anemia is a rare genetic disease of autosomal inheritance or X-linked, characterized by genomic instability and hypersensitivity to DNA cross-linking agents like diepoxybutane and mitomycin C (MMC). The basis for its diagnosis is an abnormal response to these substances, which constitutes a unique cell marker and manifests as an increased chromosomal breakage rate. Objective: To perform the analysis of the chromosomal breakages induced by mitomycin C in peripheral blood lymphocytes of Cuban patients with suspicion of Fanconi anemia. Methods: A study was conducted of chromosomal breakages induced by mitomycin C at various concentrations in cultures of T lymphocytes from venous peripheral blood of 32 patients with clinical suspicion of Fanconi anemia and an equal number of control subjects. Results: At the end of the analysis, six patients (20 percent) were diagnosed with Fanconi anemia. Of these, four showed a high percentage of breakages and two had somatic mosaicism. From a clinical point of view, four had aplastic anemia and two only presented dysmorphic features typical of the disease. Conclusions: Evaluation of the chromosomal breakages induced by mitomycin C led to the definitive diagnosis of Fanconi anemia in patients with a history of aplastic anemia, even in the absence of congenital anomalies. This is the first study of its type in a group of Cuban patients(AU)

Genome instability and lymphoma / 中南大学学报(医学版)

Lymphoma is one of the most common malignant tumor of the hematologic system. The genome instability is not only an important molecular basis for the development of lymphoma, but also has important value in the diagnosis and prognosis of lymphoma. There are 2 types of genome instability: Microsatellite instability (MSI/MIN) at gene level and chromosomal instability at chromosome level. Through the study on genes associated with lymphoma, the unstable genes associated with lymphoma could be found, meanwhile the mechanism of its occurrence and development of lymphoma could be explored, and the important basis of molecular biology could also be provided in the field of current hot lymphoma precision medical research.

Radioprotective natural products as alternative complements in oncological radiotherapy / Productos naturales radioprotectores como complementos alternativos en la radioterapia oncológica

Humans when exposed to harmful ionising radiations suffer from various pathophysiological disorders including cancer. Radiotherapy is a treatment where these cancerous cells within a tumor aretargeted and killed by means of high energy waves. This therapy is very expensive and involves highly sophisticated instruments. In addition to this, most synthetic radioprotectors including Amifostine have been found to possess toxicity. This led researchers to develop a novel, economically viable, and efficient therapeutic alternative to radiation therapy. The last two decades have observed a major shift towards investigating natural products as radioprotectors, as these are immensely effective in terms of their potential bioequivalence relative to many of the established synthetic compounds available. Taking into account the limitations of radiation therapy, an approach 'Integrative Oncology' that involves a combination of both traditional and conventional medical treatment are used nowadays to treat patients suffering from cancer and associated mental and psychological disorders.

Los seres humanos, cuando se exponen a radiaciones ionizantes nocivas, sufren diversos trastornos fisiopatológicos, incluido el cáncer. La radioterapia es un tratamiento en el que estas células cancerosas dentro de un tumor son atacadas y destruidas por medio de ondas de alta energía. Esta terapia es muy cara e implica instrumentos muy sofisticados. Además de esto, se ha descubierto que la mayoría de los radioprotectores sintéticos, incluida la amifostina, poseen toxicidad. Esto llevó a los investigadores a desarrollar una novedosa, económicamente viable y eficiente alternativa terapéutica a la radioterapia. En las dos últimas décadas se ha observado un cambio importante hacia la investigación de productos naturales como radioprotectores, ya que son inmensamente eficaces en términos de su potencial bioequivalencia en relación con muchos de los compuestos sintéticos establecidos disponibles. Teniendo en cuenta las limitaciones de la radioterapia, hoy en día se utiliza un enfoque de "Oncología Integrativa" que implica una combinación de tratamiento médico tradicional y convencional para tratar a pacientes que padecen cáncer y trastornos mentales y psicológicos asociados.

Teste de micronúcleo para detecção de instabilidade genômica em lesão cervical por papilomavírus humano / Prueba de micronúcleo para detectar inestabilidad genómica en lesión cervical por virus del papiloma humano / Micronucleus test to detect genomic instability in cervical lesion by human papillomavirus

Objetivo: analisar a produção científica acerca do teste de micronúcleo como instrumento para detecção de instabilidade genômica e dos fatores de risco para lesão intraepitelial cervical em pacientes com papilomavírus humano. Método: revisão integrativa de publicações dos últimos 10 anos, realizada no período de agosto de 2017 a junho de 2018, através da Medical Literature Analysis and Retrieval System, Literatura Latino-americana e do Caribe em Ciências da Saúde e PubMed Central. Resultados: quatro artigos foram analisados em que o teste de micronúcleo foi utilizado para detectar instabilidade genômica e risco de lesão intraepitelial cervical e seis artigos como biomarcador em diferentes estágios pré-neoplásicos, neoplásicos em lesões intraepiteliais e fatores de risco para o câncer cervical. Conclusões: o teste de micronúcleo é um método simples, rápido, barato e importante para detectar instabilidade genômica em células intraepiteliais cervicais que apresentam lesão sugestiva para o câncer de colo uterino.(AU)

Objective: to analyze the scientific production about the micronucleus test as an instrument for detecting genomic instability and risk factors for cervical intraepithelial injury in patients with human papillomavirus. Method: integrative review of publications from the last 10 years, carried out from August 2017 to June 2018, through Medical Literature Analysis and Retrieval System, Latin American and Caribbean Literature in Health Sciences and PubMed Central. Results: four articles were analyzed in which the micronucleus test was used to detect genomic instability and risk of cervical intraepithelial injury and in six articles as a biomarker in different pre-neoplastic stages, neoplastic in intraepithelial injuries and risk factors for cervical cancer. Conclusions: the micronucleus test is a simple, fast, inexpensive and important method to detect genomic instability in cervical intraepithelial cells that present lesions suggestive of cervical cancer.(AU)

Objetivo: analizar la producción científica sobre la prueba de micronúcleos como instrumento para detectar la inestabilidad genómica y los factores de riesgo de lesión intraepitelial cervical en pacientes con virus del papiloma humano. Método: revisión integradora de publicaciones de los últimos 10 años, realizada desde agosto de 2017 hasta junio de 2018, a través de la Medical Literature Analysis and Retrieval System, Literatura Latinoamericana y del Caribe en Ciencias de la Salud y PubMed Central. Resultados: se analizaron cuatro artículos en los que se utilizó la prueba de micronúcleos para detectar la inestabilidad genómica y el riesgo de lesión intraepitelial cervical y en seis artículos como biomarcador en diferentes etapas preneoplásicas, neoplásico en lesiones intraepiteliales y factores de riesgo de cáncer cervical. Conclusiones: la prueba de micronúcleos es un método simple, rápido, económico e importante para detectar la inestabilidad genómica en células intraepiteliales cervicales que presentan lesiones sugestivas de cáncer cervical.(AU)

Advances in research on the mechanism of DNA methylation in plants / 生物工程学报

DNA methylation is an epigenetic modification that forms an important regulation mechanism of gene expression in organisms across kingdoms. Aberrant patterns of DNA methylation can lead to plant developmental abnormalities. In this article, we briefly discuss DNA methylation in plants and summarize its functions and biological roles in regulating gene expression and maintaining genomic stability, plant development, as well as plant responses to biotic and abiotic stresses. We intended to provide a concise reference for further understanding of the mechanism of DNA methylation and potential applications of epigenetic manipulation for crop improvement.

Age-specific variations in hematological and biochemical parameters in middle- and large-sized of dogs

Anemia no diabetes mellitus gestacional: implicações na instabilidade genômica / Anemia in gestational diabetes mellitus: implications for genomic instability

Introdução: Evidências têm mostrado uma associação entre anemia e Diabetes Mellitus. Contudo, a relação entre anemia e Diabetes Mellitus Gestacional (DMG) ainda não está bem estabelecida, bem como sua repercussão na instabilidade genômica. Portanto, objetivou-se verificar a associação entre anemia e instabilidade genômica em mulheres com DMG atendidas em um hospital universitário. Métodos: Estudo transversal com mulheres apresentando diagnóstico de DMG que realizaram pré-natal no Hospital Universitário de Santa Maria (RS). Informações referentes ao DMG, anemia e suplementação de ferro foram obtidas nos prontuários. A instabilidade genômica foi avaliada pelo ensaio de citoma em micronúcleos em células bucais (BMCyt). Resultados: Das 44 gestantes avaliadas, 28,6% apresentaram anemia e 79,5% foram suplementadas com ferro. Das gestantes que realizaram suplementação, 75,0% não apresentaram anemia gestacional. Níveis de hemoglobina não se associaram com a instabilidade genomica (p > 0,05), mas foi observada uma associação entre brotos nucleares e os níveis de glicemia (r = 0,977; p = 0,003). Conclusão: Não foi verificado associação entre anemia e instabilidade genômica em mulheres com DMG.(AU)

Introduction: There is evidence of an association between anemia and diabetes mellitus. However, the relationship between anemia and gestational diabetes mellitus (GDM) remains to be established, as well as its impact on genomic instability. Therefore, we aimed to examine the association between anemia and genomic instability in women with GDM treated at a university hospital. Methods: A cross-sectional study of women with a diagnosis of GDM who received prenatal care at the University Hospital of Santa Maria, southern Brazil. Data on GDM, anemia, and iron supplementation were obtained from medical records. Genomic instability was assessed by the buccal micronucleus cytome (BMCyt) assay. Results: Of 44 pregnant women evaluated, 28.6% had anemia and 79.5% received iron supplementation; of the latter, 75.0% did not have gestational anemia. Hemoglobin levels were not associated with genomic instability (p > 0.05), but an association was found between nuclear buds and blood glucose levels (r = 0.977; p = 0.003). Conclusion: There was no association between anemia and genomic instability in women with GDM.(AU)

Telomere Biology in Mood Disorders: An Updated, Comprehensive Review of the Literature

Major psychiatric disorders are linked to early mortality and patients afflicted with these ailments demonstrate an increased risk of developing physical diseases that are characteristically seen in the elderly. Psychiatric conditions like major depressive disorder, bipolar disorder and schizophrenia may be associated with accelerated cellular aging, indicated by shortened leukocyte telomere length (LTL), which could underlie this connection. Telomere shortening occurs with repeated cell division and is reflective of a cell’s mitotic history. It is also influenced by cumulative exposure to inflammation and oxidative stress as well as the availability of telomerase, the telomere-lengthening enzyme. Precariously short telomeres can cause cells to undergo senescence, apoptosis or genomic instability; shorter LTL correlates with compromised general health and foretells mortality. Important data specify that LTL may be reduced in principal psychiatric illnesses, possibly in proportion to exposure to the ailment. Telomerase, as measured in peripheral blood monocytes, has been less well characterized in psychiatric illnesses, but a role in mood disorder has been suggested by preclinical and clinical studies. In this manuscript, the most recent studies on LTL and telomerase activity in mood disorders are comprehensively reviewed, potential mediators are discussed, and future directions are suggested. An enhanced comprehension of cellular aging in psychiatric illnesses could lead to their re-conceptualizing as systemic ailments with manifestations both inside and outside the brain. At the same time this paradigm shift could identify new treatment targets, helpful in bringing about lasting cures to innumerable sufferers across the globe.

Cryopreservation at -75 °C of Agaricus subrufescens on wheat grains with sucrose

Abstract Agaricus subrufescens is a basidiomycete which is studied because of its medicinal and gastronomic importance; however, less attention has been paid to its preservation. This study aimed to evaluate the effect of sucrose addition to substrate and cryotube on the viability of Agaricus subrufescens cryopreserved at -20 °C and at -75 °C for one and two years. Zero, 10% or 20% sucrose was added to potato dextrose agar or wheat grain. The mycelia were cryopreserved in the absence of cryoprotectant or with sucrose solutions at 15%, 30% or 45%. After one or two years at -75 °C or at -20 °C, mycelia were thawed and evaluated about viability, initial time of growth, colony diameter and genomic stability. Cryopreservation at -20 °C is not effective to keep mycelial viability of this fungus. Cryopreservation at -75 °C is effective when sucrose is used in substrates and/or cryotubes. Without sucrose, cryopreservation at -75 °C is effective only when wheat grains are used. Physiological characteristic as mycelial colony diameter is negatively affected when potato dextrose agar is used and unaffected when wheat grain is used after two-year cryopreservation at -75 °C. The fungus genome does not show alteration after two-year cryopreservation at -75 °C.

Mycobacterium tuberculosis promotes genomic instability in macrophages

BACKGROUND Mycobacterium tuberculosis is an intracellular pathogen, which may either block cellular defensive mechanisms and survive inside the host cell or induce cell death. Several studies are still exploring the mechanisms involved in these processes. OBJECTIVES To evaluate the genomic instability of M. tuberculosis-infected macrophages and compare it with that of uninfected macrophages. METHODS We analysed the possible variations in the genomic instability of Mycobacterium-infected macrophages using the DNA breakage detection fluorescence in situ hybridisation (DBD-FISH) technique with a whole human genome DNA probe. FINDINGS Quantitative image analyses showed a significant increase in DNA damage in infected macrophages as compared with uninfected cells. DNA breaks were localised in nuclear membrane blebs, as confirmed with DNA fragmentation assay. Furthermore, a significant increase in micronuclei and nuclear abnormalities were observed in infected macrophages versus uninfected cells. MAIN CONCLUSIONS Genomic instability occurs during mycobacterial infection and these data may be seminal for future research on host cell DNA damage in M. tuberculosis infection.

Genetic and epigenetic alterations of colorectal cancer

Colorectal cancer (CRC) arise from multi-step carcinogenesis due to genetic mutations and epigenetic modifications of human genome. Genetic mutations and epigenetic modifications were originally established as 2 independent mechanisms contributing to colorectal carcinogenesis. However, recent evidences demonstrate that there are interactions between these 2 mechanisms. Genetic mutations enable disruption of epigenetic controls while epigenetic modifications can initiate genomic instability and carcinogenesis. This review summarized genetic mutations and epigenetic modifications in colorectal carcinogenesis and molecular classification of CRC subtype based on genetic or epigenetic biomarkers for treatment response and prognosis. Molecular subtypes of CRC will permit the implementation of precision medicine with better outcome of management for CRC.

RNF126 Quenches RNF168 Function in the DNA Damage Response / 基因组蛋白质组与生物信息学报·英文版

DNA damage response (DDR) is essential for maintaining genome stability and protecting cells from tumorigenesis. Ubiquitin and ubiquitin-like modifications play an important role in DDR, from signaling DNA damage to mediating DNA repair. In this report, we found that the E3 ligase ring finger protein 126 (RNF126) was recruited to UV laser micro-irradiation-induced stripes in a RNF8-dependent manner. RNF126 directly interacted with and ubiquitinated another E3 ligase, RNF168. Overexpression of wild type RNF126, but not catalytically-inactive mutant RNF126 (CC229/232AA), diminished ubiquitination of H2A histone family member X (H2AX), and subsequent bleomycin-induced focus formation of total ubiquitin FK2, TP53-binding protein 1 (53BP1), and receptor-associated protein 80 (RAP80). Interestingly, both RNF126 overexpression and RNF126 downregulation compromised homologous recombination (HR)-mediated repair of DNA double-strand breaks (DSBs). Taken together, our findings demonstrate that RNF126 negatively regulates RNF168 function in DDR and its appropriate cellular expression levels are essential for HR-mediated DSB repair.

Human papillomavirus and genome instability: from productive infection to cancer

Infection with high oncogenic risk human papillomavirus types is the etiological factor of cervical cancer and a major cause of other epithelial malignancies, including vulvar, vaginal, anal, penile and head and neck carcinomas. These agents affect epithelial homeostasis through the expression of specific proteins that deregulate important cellular signaling pathways to achieve efficient viral replication. Among the major targets of viral proteins are components of the DNA damage detection and repair machinery. The activation of many of these cellular factors is critical to process viral genome replication intermediates and, consequently, to sustain faithful viral progeny production. In addition to the important role of cellular DNA repair machinery in the infective human papillomavirus cycle, alterations in the expression and activity of many of its components are observed in human papillomavirus-related tumors. Several studies from different laboratories have reported the impact of the expression of human papillomavirus oncogenes, mainly E6 and E7, on proteins in almost all the main cellular DNA repair mechanisms. This has direct consequences on cellular transformation since it causes the accumulation of point mutations, insertions and deletions of short nucleotide stretches, as well as numerical and structural chromosomal alterations characteristic of tumor cells. On the other hand, it is clear that human papillomavirus-transformed cells depend on the preservation of a basal cellular DNA repair activity level to maintain tumor cell viability. In this review, we summarize the data concerning the effect of human papillomavirus infection on DNA repair mechanisms. In addition, we discuss the potential of exploiting human papillomavirus-transformed cell dependency on DNA repair pathways as effective antitumoral therapies.

Non-homologous End Joining Inhibitor SCR-7 to Exacerbate Low-dose Doxorubicin Cytotoxicity in HeLa Cells

Among the genotoxic drug regimens, doxorubicin (DOX) is known for its high-dose side effects in several carcinomas, including cervical cancer. This study reports on testing the combined use of a DOX genotoxic drug and SCR-7 non-homologous end joining (NHEJ) inhibitor for HeLa cells. An in vitro DNA damaging assay of DOX was performed on plasmid and genomic DNA substrate. In vitro cytotoxicity was investigated using trypan blue dye exclusion, DNA metabolizing, and propidium iodide-based flow cytometric assays. DOX (between 20–100 μM) displayed clear DNA binding and interaction, such as the shearing and smearing of plasmid and genomic DNA. DNA metabolizing assay data indicate that HeLa lysate with DOX and SCR-7 treatment exhibited better in vitro plasmid DNA stability compared with DOX treatment alone. SCR-7 augmented the effects of low-dose DOX by demonstrating enhanced cell death from 15% to 50%. The flow cytometric data also supported that the combination of SCR-7 with DOX lead to a 23% increase in propidium iodide-based HeLa staining, thus indicating enhanced death. In summary, the inhibition of NHEJ DNA repair pathway can potentiate low-dose DOX to produce appreciable cytotoxicity in HeLa cells.

O papel da ciclina E1 no estresse replicativo e na instabilidade genômica em células epiteliais da mama / [The role of cyclin E1 in replicative stress and genomic instability in breast epithelial cells]

A ciclina E, juntamente com Cdk2, é um regulador importante da transição das fases G1/S do ciclo celular, promovendo o início e a progressão da síntese de DNA. Em alguns tipos de câncer, como o câncer de mama, os níveis de ciclina E se encontram desregulados, correlacionando com um estágio avançado do tumor e mau prognóstico. Níveis elevados de ciclina E interferem com a montagem de complexos pré-replicativos e retardam a progressão das forquilhas de replicação, levando ao fenômeno de estresse replicativo e eventualmente a instabilidade genômica. No entanto, as alterações genômicas causadas pela desregulação da ciclina E ainda não foram totalmente investigadas. Dados anteriores do nosso grupo demonstraram que altos níveis de ciclina E1 retardam a progressão pela fase S, permitindo que células entrem em mitose antes do término da replicação do DNA. A replicação incompleta do DNA induz aberrações cromossômicas em regiões genômicas específicas, como sítios frágeis. O objetivo deste projeto é avaliar o efeito da desregulação de ciclina E1 na instabilidade genômica de células epiteliais da mama ao longo da proliferação celular. Para estabelecer o modelo de estresse replicativo, células do epitélio da mama humana imortalizadas (HME1) foram transduzidas com adenovírus controle (Adv-Controle) ou com adenovírus que codifica o cDNA de ciclina E1 humana (Adv-Ciclina E1). Como controle positivo, foram utilizadas as linhagens celulares de câncer da mama SUM149PT e MDA-MB-157, que têm níveis aumentados de ciclina E1. Nossos resultados indicam que altos níveis de ciclina E1 não interferem com a proliferação de células HME1. Contudo, análises de citometria de fluxo indicam que altos níveis de ciclina E1 reduzem o número de células na fase G1, reduzem a progressão pela fase S e atrasam a entrada nas fases G2/M ao longo de 7 dias. A desregulação de ciclina E1 não induz a morte celular, mas induz eventos de poliploidia. Células HME1 tratadas com a afidicolina, um inibidor de DNA polimerase, progridem mais lentamente pela fase S, mas não apresentam alterações na morte celular ou poliploidia. Além disso, células HME1 com desregulação de ciclina E1 apresentam aberrações cromossômicas, como endorreduplicação, hiperfragmentação cromossômica e separação prematura de cromátides irmãs quando comparadas com células controle. No momento, estamos avaliando a instabilidade de sítios frágeis específicos em células HME1 com altos níveis de ciclina E1 usando Hibridização Fluorescente In Situ (FISH). Além disso, células HME1 com níveis elevados de ciclina E1 serão analisadas através de cariótipo por bandeamento G. O objetivo deste projeto é contribuir para a caracterização das alterações genéticas mediadas por ciclina E1 durante a carcinogênese da mama.

DNA damage to human genetic disorders with neurodevelopmental defects

Although some mutations are beneficial and are the driving force behind evolution, it is important to maintain DNA integrity and stability because it contains genetic information. However, in the oxygen-rich environment we live in, the DNA molecule is under constant threat from endogenous or exogenous insults. DNA damage could trigger the DNA damage response (DDR), which involves DNA repair, the regulation of cell cycle checkpoints, and the induction of programmed cell death or senescence. Dysregulation of these physiological responses to DNA damage causes developmental defects, neurological defects, premature aging, infertility, immune system defects, and tumors in humans. Some human syndromes are characterized by unique neurological phenotypes including microcephaly, mental retardation, ataxia, neurodegeneration, and neuropathy, suggesting a direct link between genomic instability resulting from defective DDR and neuropathology. In this review, rare human genetic disorders related to abnormal DDR and damage repair with neural defects will be discussed.

Structural Variation of Alu Element and Human Disease

Transposable elements are one of major sources to cause genomic instability through various mechanisms including de novo insertion, insertion-mediated genomic deletion, and recombination-associated genomic deletion. Among them is Alu element which is the most abundant element, composing ~10% of the human genome. The element emerged in the primate genome 65 million years ago and has since propagated successfully in the human and non-human primate genomes. Alu element is a non-autonomous retrotransposon and therefore retrotransposed using L1-enzyme machinery. The 'master gene' model has been generally accepted to explain Alu element amplification in primate genomes. According to the model, different subfamilies of Alu elements are created by mutations on the master gene and most Alu elements are amplified from the hyperactive master genes. Alu element is frequently involved in genomic rearrangements in the human genome due to its abundance and sequence identity between them. The genomic rearrangements caused by Alu elements could lead to genetic disorders such as hereditary disease, blood disorder, and neurological disorder. In fact, Alu elements are associated with approximately 0.1% of human genetic disorders. The first part of this review discusses mechanisms of Alu amplification and diversity among different Alu subfamilies. The second part discusses the particular role of Alu elements in generating genomic rearrangements as well as human genetic disorders.