RESUMO
The main goal of chemotherapeutic drugs is to induce massive cell death in tumors. Cisplatin is an antitumor drug widely used to treat several types of cancer. Despite its remarkable efficiency, most tumors show intrinsic or acquired drug resistance. The primary biological target of cisplatin is genomic DNA, and it causes a plethora of DNA lesions that block transcription and replication. These cisplatin-induced DNA lesions strongly induce cell death if they are not properly repaired or processed. To counteract cisplatin-induced DNA damage, cells use an intricate network of mechanisms, including DNA damage repair and translesion synthesis. In this review, we describe how cisplatin-induced DNA lesions are repaired or tolerated by cells and focus on the pivotal role of DNA repair and tolerance mechanisms in tumor resistance to cisplatin. In fact, several recent clinical findings have correlated the tumor cell status of DNA repair/translesion synthesis with patient response to cisplatin treatment. Furthermore, these mechanisms provide interesting targets for pharmacological modulation that can increase the efficiency of cisplatin chemotherapy.
Assuntos
Antineoplásicos/uso terapêutico , Cisplatino/uso terapêutico , Dano ao DNA/genética , Reparo do DNA/genética , Resistencia a Medicamentos Antineoplásicos/genética , Dano ao DNA/efeitos dos fármacos , HumanosRESUMO
The main goal of chemotherapeutic drugs is to induce massive cell death in tumors. Cisplatin is an antitumor drug widely used to treat several types of cancer. Despite its remarkable efficiency, most tumors show intrinsic or acquired drug resistance. The primary biological target of cisplatin is genomic DNA, and it causes a plethora of DNA lesions that block transcription and replication. These cisplatin-induced DNA lesions strongly induce cell death if they are not properly repaired or processed. To counteract cisplatin-induced DNA damage, cells use an intricate network of mechanisms, including DNA damage repair and translesion synthesis. In this review, we describe how cisplatin-induced DNA lesions are repaired or tolerated by cells and focus on the pivotal role of DNA repair and tolerance mechanisms in tumor resistance to cisplatin. In fact, several recent clinical findings have correlated the tumor cell status of DNA repair/translesion synthesis with patient response to cisplatin treatment. Furthermore, these mechanisms provide interesting targets for pharmacological modulation that can increase the efficiency of cisplatin chemotherapy.
Assuntos
Humanos , Dano ao DNA/genética , Cisplatino/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Reparo do DNA/genética , Antineoplásicos/uso terapêutico , Dano ao DNA/efeitos dos fármacosRESUMO
Aptamers are oligonucleotide reagents with high affinity and specificity, which among other therapeutic and diagnostic applications have the capability of acting as delivery agents. Thus, aptamers are capable of carrying small molecules, nanoparticles, radiopharmaceuticals or fluorescent agents as well as nucleic acid therapeutics specifically to their target cells. In most cases, the molecules may possess interesting therapeutic properties, but their lack of specificity for a particular cell type, or ability to internalise in such a cell, hinders their clinical development, or cause unwanted side effects. Thus, chemotherapy or radiotherapy agents, famous for their side effects, can be coupled to aptamers for specific delivery. Equally, siRNA have great therapeutic potential and specificity, but one of their shortcomings remain the delivery and internalisation into cells. Various methodologies have been proposed to date, including aptamers, to resolve this problem. Therapeutic or imaging reagents benefit from the adaptability and ease of chemical manipulation of aptamers, their high affinity for the specific marker of a cell type, and their internalisation ability via cell mediated endocytosis. In this review paper, we explore the potential of the aptamers as delivery agents and offer an update on current status and latest advancements.
Assuntos
Antineoplásicos/administração & dosagem , Aptâmeros de Nucleotídeos/química , Neoplasias/terapia , RNA Interferente Pequeno/administração & dosagem , Compostos Radiofarmacêuticos/administração & dosagem , Humanos , Nanopartículas/químicaRESUMO
The caspase-3-cleaved presence was evaluated in this study in the heart of irradiated rats, during the decline of ventricular function. Female Wistar rats were irradiated with a single dose of radiation (15 Gy) delivered directly to the heart and the molecular, histological and physiological evaluations were performed at thirteen months post-irradiation. The expressions of procollagen type I, TGF-ß1 and caspase-3-cleaved were analyzed using Western blotting. Cardiac structural and functional alterations were investigated by echocardiography and electron microscopy. In the irradiated group, the levels of procollagen type I, TGF-ß1 and caspase-3-cleaved are increased. Significant histological changes (degeneration of heart tissue and collagen deposition) and functional (reduced ejection fraction) were observed. Data suggest that the cardiac function decline after exposure to ionizing radiation is related, in part, to increased collagen and increased caspase-3-cleaved.
Assuntos
Caspase 3/metabolismo , Colágeno Tipo I/metabolismo , Coração/efeitos da radiação , Miocárdio/enzimologia , Fator de Crescimento Transformador beta1/metabolismo , Animais , Western Blotting , Relação Dose-Resposta à Radiação , Ecocardiografia , Ativação Enzimática/efeitos da radiação , Feminino , Microscopia Eletrônica de Transmissão , Miocárdio/ultraestrutura , Ratos , Ratos WistarRESUMO
Nucleotide excision repair (NER) is the most flexible of all known DNA-repair mechanisms, and XPG is a 3'-endonuclease that participates in NER. Mutations in this gene (ERCC5) may result in the human syndrome xeroderma pigmentosum (XP) and, in some cases, in the complex phenotype of Cockayne syndrome (CS). Two Brazilian XP siblings, who were mildly affected, were investigated and classified into the XP-G group. The cells from these patients were highly ultraviolet (UV) sensitive but not sensitive to photosensitized methylene blue, an agent that causes oxidative stress. This phenotype is in contrast to XP-G/CS cells, which are highly sensitive to this oxidative agent. Sequencing revealed a compound heterozygous genotype with two novel missense mutations: c.83C>A (p.Ala28Asp) and c.2904G>C (p.Trp968Cys). The first mutation maps to the catalytic site of the XPG protein, whereas the second may compromise binding to DNA. Functional assays indicated that the mutated alleles were unable to perform the complete repair of UV-irradiated plasmids; however, full correction was observed for oxidatively damaged plasmids. Therefore, the XP phenotype of these patients is caused by novel missense mutations that specifically affect DNA repair for UV- but not oxidative-stress-induced DNA damage, and implications for XP versus XP/CS phenotype are discussed.
Assuntos
Sobrevivência Celular/efeitos da radiação , Reparo do DNA/efeitos da radiação , Proteínas de Ligação a DNA/genética , Endonucleases/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Adolescente , Alelos , Sequência de Aminoácidos , Brasil , Linhagem Celular , Clonagem Molecular , Síndrome de Cockayne/genética , Dano ao DNA/efeitos da radiação , Feminino , Fibroblastos/citologia , Fibroblastos/efeitos da radiação , Heterozigoto , Humanos , Masculino , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Estresse Oxidativo/efeitos da radiação , Fenótipo , Conformação Proteica , Alinhamento de Sequência , Análise de Sequência de DNA , Raios Ultravioleta , Xeroderma Pigmentoso/genética , Adulto JovemRESUMO
PURPOSE: To investigate changes in cardiac functional parameters and the cardiac expression of angiotensin-converting enzyme (ACE), angiotensin II type 1 receptor (AT1), procollagen type I (proc-I) and transforming growth factor-ß1 (TGF-ß1) in rats irradiated at heart. MATERIAL AND METHODS: Male Wistar rats were irradiated with a single dose of radiation (0, 5, 10 and 15 Gray [Gy]) delivered directly to the heart and the molecular evaluations were performed at various times post-irradiation (two days, 15 days and four months). The expression of ACE, AT1, proc-I and TGF-ß1 were analysed using Real Time-Polymerase Chain Reaction (RT-PCR) and/or Western blotting. Cardiac structural and functional alterations were investigated at the four-month time point by echocardiography and by quantitative methods (stereology). RESULTS: Rats irradiated with 15 Gy showed a modest reduction in the ejection fraction. Cardiac proc-I, TGF-ß1, ACE and AT1 were also measurably increased. CONCLUSIONS: Irradiated rat hearts show simultaneous elevations in renin-angiotensin system components AT1 and ACE and cardiac remodeling markers proc-I and TGF-ß1.
Assuntos
Peptidil Dipeptidase A/genética , Peptidil Dipeptidase A/metabolismo , Receptor Tipo 1 de Angiotensina/genética , Receptor Tipo 1 de Angiotensina/metabolismo , Regulação para Cima/efeitos da radiação , Animais , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Relação Dose-Resposta à Radiação , Coração/fisiologia , Coração/efeitos da radiação , Masculino , Miócitos Cardíacos/citologia , Miócitos Cardíacos/efeitos da radiação , Ratos , Ratos Wistar , Sistema Renina-Angiotensina/efeitos da radiação , Fator de Crescimento Transformador beta1/genética , Fator de Crescimento Transformador beta1/metabolismoRESUMO
The concentration of free circulating plasma DNA and the genetic profile of patients suffering from various types of tumors were studied in an effort to increase the understanding of the biomarkers and genetic factors involved in predisposing an individual to lung cancer (LC). The polymorphic inheritance of glutathione S-transferases (GST), which modulate the effects of various genotoxic agents, especially those derived from benzo[a]pyrene, one of the main tobacco carcinogens, has been implicated in both cancer risk and prognostics. We investigated gene polymorphisms in the blood serum of patients previously diagnosed at the Pneumology Division of the Clementino Fraga Filho University Hospital of the Federal University of Rio de Janeiro and in buccal swab samples of exfoliated oral cells obtained from a population of healthy controls. The distribution of GSTM1 and GSTT1 polymorphisms was not significantly different between LC patients and the controls, suggesting that GSTM1 and GSTT1 alone or in combination are not independent risk factors for LC. However, a close relationship between smoking status and LC was clearly demonstrated. The most significant risk for LC concerning tobacco smoking was found in the association of null genotypes for GSTM1 and GSTT1 (P < 0.0001).
Assuntos
DNA/sangue , Glutationa Transferase , Neoplasias Pulmonares , Polimorfismo Genético , Adulto , Idoso , Brasil , Feminino , Frequência do Gene , Predisposição Genética para Doença , Genótipo , Glutationa Transferase/sangue , Glutationa Transferase/genética , Humanos , Neoplasias Pulmonares/sangue , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/genética , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Lanthanum (La) is a rare-earth metal with applications in agriculture, industry, and medicine. Since lanthanides show a broad spectrum of applications there is an increased risk of contamination for humans. We examined the effects of lanthanum in Jurkat cells and human peripheral lymphocytes (HPL), and we found that it was cytotoxic and genotoxic on both cell lines. Additionally, HPL were more sensitive to La treatment than Jurkat cells and necrosis was the pathway by which La induced cytotoxicity. Vitamin E was able to diminish the DNA strand breaks induced suggesting that oxidative stress may be involved in the genotoxic process.
Assuntos
Carcinógenos/toxicidade , Poluentes Ambientais/toxicidade , Lantânio/toxicidade , Linfócitos/efeitos dos fármacos , Mutagênicos/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Antagonismo de Drogas , Combinação de Medicamentos , Poluentes Ambientais/classificação , Humanos , Células Jurkat , Lantânio/classificação , Linfócitos/patologia , Necrose/induzido quimicamente , Vitamina E/farmacologiaRESUMO
Inherited deleterious mutations in one of the Fanconi anemia genes lead to a disease, characterized by bone marrow failure, myeloid leukemia, and hypersensitivity to DNA damage. We identified proteins likely associated to the molecular signaling pathways involved in DNA repair of interstrand cross-link lesions and in mechanisms of genomic stability mediated by FA/BRCA pathways. We compared protein maps resolved by bidimensional electrophoresis and analyzed differentially expressed proteins, by mass spectrometry, between FA complementation group C (FANCC)-deficient cells, and their ectopically corrected counterpart in physiological conditions or after treatment with MMC. We found six differentially expressed proteins; among them, the checkpoint mediator protein MDC1 whose expression was disrupted in FANCC-/- cells. The potential role of differentially expressed proteins in FA phenotype is discussed.
Assuntos
Proteína BRCA2/genética , Proteína do Grupo de Complementação C da Anemia de Fanconi/genética , Proteínas de Grupos de Complementação da Anemia de Fanconi/genética , Anemia de Fanconi/genética , Regulação da Expressão Gênica/genética , Proteínas Nucleares/genética , Transdução de Sinais/genética , Transativadores/genética , Proteínas Adaptadoras de Transdução de Sinal , Proteínas Reguladoras de Apoptose , Proteínas de Ciclo Celular , Linhagem Celular , Proteínas de Ligação a DNA/genética , Deleção de Genes , Humanos , Mutagênese Sítio-DirigidaRESUMO
Hydrogen peroxide is an important reactive oxygen species (ROS) that arises either during the aerobic respiration process or as a by-product of water radiolysis after exposure to ionizing radiation. The reaction of hydrogen peroxide with transition metals imposes on cells an oxidative stress condition that can result in damage to cell components such as proteins, lipids and principally to DNA, leading to mutagenesis and cell death. Escherichia coli cells are able to deal with these adverse events via DNA repair mechanisms, which enable them to recover their genome integrity. These include base excision repair (BER), nucleotide excision repair (NER) and recombinational repair. Other important defense mechanisms present in Escherichia coli are OxyR and SosRS anti-oxidant inducible pathways, which are elicited by cells to avoid the introduction of oxidative lesions by hydrogen peroxide. This review summarizes the phenomena of lethal synergism between UV irradiation (254 nm) and H2O2, the cross-adaptive response between different classes of genotoxic agents and hydrogen peroxide, and the role of copper ions in the lethal response to H2O2 under low-iron conditions.
Assuntos
Dano ao DNA , Escherichia coli , Peróxido de Hidrogênio , Cobre , Reações Cruzadas , Genoma , FerroRESUMO
Chemotherapeutic agents such as mitomycin C or nitrogen mustards induce DNA inter-strand cross-links (ICL) and are highly toxic, thus constituting an useful tool to treat some human degenerative diseases, such as cancer. Additionally, psoralens plus UV-A (PUVA), which also induce ICL, find use in treatment of patients afflicted with psoriasis and vitiligo. The repair of DNA ICL generated by different molecules involves a number of multi-step DNA repair pathways. In bacteria, as in eukaryotic cells, if DNA ICL are not tolerated or repaired via nucleotide excision repair (NER), homologous recombination or translesion synthesis pathways, these DNA lesions may lead to mutations and cell death. Herein, we bring new insights to the role of Escherichia coli nucleotide excision repair genes uvrA, uvrB and uvrC in the repair of DNA damage induced by some chemotherapeutic agents and psoralen derivatives plus UV-A. These new observations point to a novel role for the UvrB protein, independent of its previously described role in the Uvr(A)BC complex, which could be specific for repair of monoadducts, intra-strand biadducts and/or ICL.
Assuntos
Antineoplásicos/farmacologia , Adutos de DNA/efeitos dos fármacos , Reparo do DNA/genética , Escherichia coli/genética , Furocumarinas/farmacologia , Raios Ultravioleta , Reparo do DNA/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , HumanosRESUMO
Oxyygen free radicals are highly reactive species that damage several cellular macromolecules and organelles, including membrane lipid peroxidation and produce DNA lesions. We have discussed here; i) The mechanism of radiation-induced cellular damage in bacteria through the intermediation of active oxygen species; ii) the cellular inactivation and the role of bacterial SOS and OxyR systems in the repair of lesions induced by H2O2 under low iron condition; iii) the lethal interaction between H2O2 and o-phenanthroline in E. coli; iv) the biological response induced by near-UV radiation mediated by active oxygen species and finally v) the mutagenic potential of popular plant extracts like guaraná (Paullinia cupana), mate (Ilex paraguariensis) and saiao (Kalanchoe brasiliensis), whose effects are eventually mediated by active oxygen species.
Assuntos
Bactérias , Células/efeitos da radiação , Dano ao DNA , Espécies Reativas de Oxigênio , Oxidantes/farmacologia , Estresse Oxidativo , Peroxidação de Lipídeos , Peróxido de Hidrogênio/farmacologia , Escherichia coli , Radicais Livres , Ferro , Mutagênese , Extratos Vegetais , Plantas Medicinais , Radiação IonizanteRESUMO
Uma soluçäo aquosa de Euphorbia tirucalli (avelós) coletada em locais ensolarados mostrou atividade moluscicida para Biomphalaria glabrata obtendo-se a LD50 a uma concentraçäo de 28,0 ppm e a LD90 a 85,0 ppm. A toxicidade do produto para peixes foi similar a de Bayluscide e sulfato de cobre testados comparativamente. Pela larga distribuiçäo da planta e sua fácil propagaçäo e extraçäo da substância ativa, e pela ausência de efeito residual, a planta pode ser considerada como promissora para testes de campo em locais restritos