RESUMO
Protein kinase CK2 is a highly pleiotropic protein kinase capable of phosphorylating hundreds of protein substrates. It is involved in numerous cellular functions, including cell viability, apoptosis, cell proliferation and survival, angiogenesis, or ER-stress response. As CK2 activity is found perturbed in many pathological states, including cancers, it becomes an attractive target for the pharma. A large number of low-mass ATP-competitive inhibitors have already been developed, the majority of them halogenated. We tested the binding of six series of halogenated heterocyclic ligands derived from the commercially available 4,5-dihalo-benzene-1,2-diamines. These ligand series were selected to enable the separation of the scaffold effect from the hydrophobic interactions attributed directly to the presence of halogen atoms. In silico molecular docking was initially applied to test the capability of each ligand for binding at the ATP-binding site of CK2. HPLC-derived ligand hydrophobicity data are compared with the binding affinity assessed by low-volume differential scanning fluorimetry (nanoDSF). We identified three promising ligand scaffolds, two of which have not yet been described as CK2 inhibitors but may lead to potent CK2 kinase inhibitors. The inhibitory activity against CK2α and toxicity against four reference cell lines have been determined for eight compounds identified as the most promising in nanoDSF assay.
Assuntos
Caseína Quinase II/química , Halogenação , Compostos Heterocíclicos/síntese química , Fenilenodiaminas/química , Trifosfato de Adenosina/química , Domínio Catalítico , Cromatografia Líquida de Alta Pressão/métodos , Fluorometria/métodos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Simulação de Acoplamento MolecularRESUMO
Phosphodiesterase 5 (PDE5) is one of the most extensively studied phosphodiesterases that is highly specific for cyclic-GMP hydrolysis. PDE5 became a target for drug development based on its efficacy for treatment of erectile dysfunction. In the present study, we synthesized four novel analogues of the phosphodiesterase type 5 (PDE5) inhibitor-tadalafil, which differs in (i) ligand flexibility (rigid structure of tadalafil vs. conformational flexibility of newly synthesized compounds), (ii) stereochemistry associated with applied amino acid building blocks, and (iii) substitution with bromine atom in the piperonyl moiety. For both the intermediate and final compounds as well as for the parent molecule, we have established the crystal structures and performed a detailed analysis of their structural features. The initial screening of the cytotoxic effect on 16 different human cancer and non-cancer derived cell lines revealed that in most cases, the parent compound exhibited a stronger cytotoxic effect than new derivatives, except for two cell lines: HEK 293T (derived from a normal embryonic kidney, that expresses a mutant version of SV40 large T antigen) and MCF7 (breast adenocarcinoma). Two independent studies on the inhibition of PDE5 activity, based on both pure enzyme assay and modulation of the release of nitric oxide from platelets under the influence of tadalafil and its analogues revealed that, unlike a reference compound that showed strong PDE5 inhibitory activity, the newly obtained compounds did not have a noticeable effect on PDE5 activity in the range of concentrations tested. Finally, we performed an investigation of the toxicological effect of synthesized compounds on Caenorhabditis elegans in the highest applied concentration of 6a,b and 7a,b (160 µM) and did not find any effect that would suggest disturbance to the life cycle of Caenorhabditis elegans. The lack of toxicity observed in Caenorhabditis elegans and enhanced, strengthened selectivity and activity toward the MCF7 cell line made 7a,b good leading structures for further structure activity optimization and makes 7a,b a reasonable starting point for the search of new, selective cytotoxic agents.
Assuntos
Caenorhabditis elegans/enzimologia , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/metabolismo , Inibidores da Fosfodiesterase 5 , Piperazinas , Tadalafila , Animais , Avaliação Pré-Clínica de Medicamentos , Células HEK293 , Humanos , Células MCF-7 , Inibidores da Fosfodiesterase 5/síntese química , Inibidores da Fosfodiesterase 5/química , Inibidores da Fosfodiesterase 5/farmacologia , Piperazinas/síntese química , Piperazinas/química , Piperazinas/farmacologia , Tadalafila/análogos & derivados , Tadalafila/síntese química , Tadalafila/química , Tadalafila/farmacologiaRESUMO
4-Hydroxy-2-nonenal (HNE) is a reactive α,ß-unsaturated aldehyde generated during oxidative stress and subsequent peroxidation of polyunsaturated fatty acids. Here, Werner protein (WRN) was identified as a novel target for modification by HNE. Werner syndrome arises through mutations in the WRN gene that encodes the RecQ DNA helicase which is critical for maintaining genomic stability. This hereditary disease is associated with chromosomal instability, premature aging and cancer predisposition. WRN appears to participate in the cellular response to oxidative stress and cells devoid of WRN display elevated levels of oxidative DNA damage. We demonstrated that helicase/ATPase and exonuclease activities of HNE-modified WRN protein were inhibited both in vitro and in immunocomplexes purified from the cell extracts. Sites of HNE adduction in human WRN were identified at Lys577, Cys727, His1290, Cys1367, Lys1371 and Lys1389. We applied in silico modeling of the helicase and RQC domains of WRN protein with HNE adducted to Lys577 and Cys727 and provided a potential mechanism of the observed deregulation of the protein catalytic activities. In light of the obtained results, we postulate that HNE adduction to WRN is a post-translational modification, which may affect WRN conformational stability and function, contributing to features and diseases associated with premature senescence.
Assuntos
Aldeídos/química , Exodesoxirribonucleases/química , Exodesoxirribonucleases/metabolismo , RecQ Helicases/química , RecQ Helicases/metabolismo , Adenosina Trifosfatases/antagonistas & inibidores , Aldeídos/análise , Animais , Biocatálise , Células Cultivadas , DNA/metabolismo , Exodesoxirribonucleases/antagonistas & inibidores , Humanos , Modelos Moleculares , RecQ Helicases/antagonistas & inibidores , Helicase da Síndrome de WernerRESUMO
The aim of this work was to answer the question whether the broad range of parameters which describe oxidative stress and oxidatively damaged DNA and repair are appropriate prognosis factors of colon cancer (CRC) patients survival? The following parameters were analyzed for 89 CRC patients: concentration of uric acid and vitamins A, E, C in plasma; levels of 8-oxodGuo (8-oxo-7,8-dihydro-2'-deoxyguanosine) in DNA of leukocyte and colon tissues; urinary excretion rates of 8-oxodGuo and 8-oxoGua (8-oxo-7,8-dihydroguanine); the activity and mRNA or protein level of repair enzymes OGG1, APE1, ANPG, TDG and PARP1. All DNA modifications and plasma antioxidants were analyzed using high performance liquid chromatography (HPLC) or HPLC/gas chromatography-mass spectrometry techniques. Expression of repair proteins was analyzed by QPCR, Western or immunohistochemistry methods. Longer survival coincided with low levels of 8-oxodGuo/8oxoGua in urine and 8-oxodGuo in DNA as well as with high concentration of uric acid plasma level. In contrast to expectations, longer survival coincided with lower mRNA level in normal colon tissue of the main 8-oxoGua DNA glycosylase, OGG1, but no association was found for PARP-1 expression. When analyzing simultaneously two parameters the discriminating power increased significantly. Combination of low level of urinary 8-oxoGua together with low level of 8-oxodGuo in leukocyte (both below median value) or high concentration of plasma uric acid (above median value) have the best prediction power. Since prediction value of these parameters seems to be comparable to conventional staging procedure, they could possibly be used as markers to predict clinical success in CRC treatment.
Assuntos
Adenocarcinoma/mortalidade , Biomarcadores Tumorais/análise , Neoplasias do Colo/mortalidade , Desoxiguanosina/análogos & derivados , Guanina/análogos & derivados , Ácido Úrico/sangue , 8-Hidroxi-2'-Desoxiguanosina , Adenocarcinoma/diagnóstico , Adenocarcinoma/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Cromatografia Líquida de Alta Pressão , Neoplasias do Colo/diagnóstico , Neoplasias do Colo/metabolismo , Dano ao DNA/genética , Enzimas Reparadoras do DNA/genética , Desoxiguanosina/análise , Desoxiguanosina/genética , Feminino , Seguimentos , Cromatografia Gasosa-Espectrometria de Massas , Guanina/análise , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Estresse Oxidativo , Prognóstico , Taxa de SobrevidaRESUMO
Benzodiazepines that consist of one α- and one ß-amino acid residues linked together in a seven-membered heterocyclic ring could be treated as small, rigid, cyclic dipeptides capable of exhibiting a wide range of biological activities. During our research on novel analogues of anthramycin, a tricyclic antibiotic benzodiazepine, we developed the synthesis of two benzodiazepine dimers, obtained through the cyclization of appropriate linear tripeptides. The synthesized compounds were tested on a panel of seven cancer and normal cell lines. The developed molecules exhibited promising cytotoxic activity against the lung cancer cell lines A549 and NCI-H1299 and the epidermoid carcinoma cell line A-431. Moreover, they showed significant selectivity compared to the reference cell lines (BJ-human normal skin fibroblasts and MRC-5-human normal lung cell line). When tested on two isogenic cell lines, HCT116 and HCT116p53-/- (colon cancer), contrary to cisplatin being used as a positive control, the obtained compounds showed a cytotoxic effect independent of the p53 protein status. For the above reasons, the obtained compounds can be considered a new group of promising anticancer agents, useful in the fight against p53-dependent drug resistance in cancers. They can also be treated as convenient, leading structures suitable for further optimization and searching for more active and selective molecules.
Assuntos
Antineoplásicos , Neoplasias Pulmonares , Humanos , Proteína Supressora de Tumor p53 , Benzodiazepinas , Antineoplásicos/farmacologia , Resistência a Medicamentos , Peptídeos/farmacologia , Linhagem Celular Tumoral , Proliferação de CélulasRESUMO
Inflammation, high fat, high red meat and low fiber consumption have for long been known as the most important etiological factors of sporadic colorectal cancers (CRC). Colon cancer originates from neoplastic transformation in a single layer of epithelial cells occupying colonic crypts, in which migration and apoptosis program becomes disrupted. This results in the formation of polyps and metastatic cancers. Mutational program in sporadic cancers involves APC gene, in which mutations occur most abundantly in the early phase of the process. This is followed by mutations in RAS, TP53, and other genes. Progression of carcinogenic process in the colon is accompanied by augmentation of the oxidative stress, which manifests in the increased level of oxidatively damaged DNA both in the colon epithelium, and in blood leukocytes and urine, already at the earliest stages of disease development. Defence mechanisms are deregulated in CRC patients: (i) antioxidative vitamins level in blood plasma declines with the development of disease; (ii) mRNA level of base excision repair enzymes in blood leukocytes of CRC patients is significantly increased; however, excision rate is regulated separately, being increased for 8-oxoGua, while decreased for lipid peroxidation derived ethenoadducts, ÉAde and ÉCyt; (iii) excision rate of ÉAde and ÉCyt in colon tumors is significantly increased in comparison to asymptomatic colon margin, and ethenoadducts level is decreased. This review highlights mechanisms underlying such deregulation, which is the driving force to colon carcinogenesis.
Assuntos
Neoplasias do Colo/genética , Dano ao DNA , Reparo do DNA , Estresse Oxidativo , 8-Hidroxi-2'-Desoxiguanosina/análogos & derivados , Transformação Celular Neoplásica/metabolismo , Neoplasias do Colo/metabolismo , Adutos de DNA/metabolismo , Guanina/análogos & derivados , Guanina/metabolismo , HumanosRESUMO
Human RECQL5 is a member of the RecQ helicase family which is implicated in genome maintenance. Five human members of the family have been identified; three of them, BLM, WRN and RECQL4 are associated with elevated cancer risk. RECQL1 and RECQL5 have not been linked to any human disorder yet; cells devoid of RECQL1 and RECQL5 display increased chromosomal instability. Here, we report the physical and functional interaction of the large isomer of RECQL5, RECQL5beta, with the human flap endonuclease 1, FEN1, which plays a critical role in DNA replication, recombination and repair. RECQL5beta dramatically stimulates the rate of FEN1 cleavage of flap DNA substrates. Moreover, we show that RECQL5beta and FEN1 interact physically and co-localize in the nucleus in response to DNA damage. Our findings, together with the previous literature on WRN, BLM and RECQL4's stimulation of FEN1, suggests that the ability of RecQ helicases to stimulate FEN1 may be a general feature of this class of enzymes. This could indicate a common role for the RecQ helicases in the processing of oxidative DNA damage.
Assuntos
Endonucleases Flap/metabolismo , RecQ Helicases/metabolismo , Linhagem Celular , Núcleo Celular/enzimologia , DNA/química , DNA/metabolismo , Clivagem do DNA , DNA de Cadeia Simples/metabolismo , Endonucleases Flap/análise , Humanos , RecQ Helicases/análiseRESUMO
RECQL4 is a human RecQ helicase which is mutated in approximately two-thirds of individuals with Rothmund-Thomson syndrome (RTS), a disease characterized at the cellular level by chromosomal instability. BLM and WRN are also human RecQ helicases, which are mutated in Bloom and Werner's syndrome, respectively, and associated with chromosomal instability as well as premature aging. Here we show that primary RTS and RECQL4 siRNA knockdown human fibroblasts accumulate more H(2)O(2)-induced DNA strand breaks than control cells, suggesting that RECQL4 may stimulate repair of H(2)O(2)-induced DNA damage. RTS primary fibroblasts also accumulate more XRCC1 foci than control cells in response to endogenous or induced oxidative stress and have a high basal level of endogenous formamidopyrimidines. In cells treated with H(2)O(2), RECQL4 co-localizes with APE1, and FEN1, key participants in base excision repair. Biochemical experiments indicate that RECQL4 specifically stimulates the apurinic endonuclease activity of APE1, the DNA strand displacement activity of DNA polymerase beta, and incision of a 1- or 10-nucleotide flap DNA substrate by Flap Endonuclease I. Additionally, RTS cells display an upregulation of BER pathway genes and fail to respond like normal cells to oxidative stress. The data herein support a model in which RECQL4 regulates both directly and indirectly base excision repair capacity.
Assuntos
Reparo do DNA , RecQ Helicases/genética , Biocatálise , Células Cultivadas , Dano ao DNA , DNA Polimerase beta/metabolismo , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Proteínas de Ligação a DNA/genética , Guanina/análogos & derivados , Guanina/metabolismo , Humanos , Peróxido de Hidrogênio/farmacologia , Análise de Sequência com Séries de Oligonucleotídeos , Pirimidinas/metabolismo , RNA Interferente Pequeno/genética , RecQ Helicases/metabolismo , Síndrome de Rothmund-Thomson/genética , Síndrome de Rothmund-Thomson/metabolismo , Proteína 1 Complementadora Cruzada de Reparo de Raio-XRESUMO
Decreased repair of oxidative DNA damage is a risk factor for developing certain human malignancies. We have previously found that the capacity of 8-oxo-7,8-dihydroguanine repair was lower in leukocytes of NSCLC patients than in controls. To explain these observations, we searched for mutations and polymorphisms in the OGG1 gene among 88 NSCLC patients and 79 controls. One patient exhibited a heterozygous mutation in exon 1, which resulted in Arg46Gln substitution. Normal lung and tumor tissue carrying this mutation showed markedly lower 8-oxoG incision activity than the mean for all patients. The predominant polymorphism of OGG1 was Ser326Cys. A significant difference was observed in the frequencies of the OGG1 variants between populations of NSCLC patients and controls. The frequency of the Cys326 allele and the number of Cys326Cys homozygotes was higher among patients than controls. In individuals with either Ser326Cys or Cys326Cys genotype 8-oxoG incision rate was lower than in those with both Ser326 alleles, either in lung or leukocytes. Moreover, 8-oxodG level was higher in lung tissue and leukocytes of patients carrying two Cys326 alleles and in leukocytes of patients with the Ser326Cys genotype. We also screened for polymorphisms of the XRCC1 gene. Only heterozygotes of the XRCC1 variants Arg194Trp, Arg280His and Arg399Gln were found among patients and controls, with the frequency of Arg280His being significantly higher among patients. NSCLC patients with Arg280His or Arg399Gln polymorphism revealed lower 8-oxoG incision activity in their lung tissues, but not in leukocytes. We can conclude that the OGG1 Ser326Cys polymorphisms may have an impact on the efficiency of 8-oxoG incision in humans and the XRCC1 His280 and Gln399 may influence the OGG1 activity in tissues exposed to chronic oxidative/inflammatory stress. Higher frequency of the OGG1 Cys326 allele among NSCLC patients may partially explain the impairment of the 8-oxoG repair observed in their leukocytes.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/genética , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Desoxiguanosina/análogos & derivados , Guanina/análogos & derivados , Neoplasias Pulmonares/genética , Polimorfismo Genético , 8-Hidroxi-2'-Desoxiguanosina , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Desoxiguanosina/genética , Feminino , Guanina/metabolismo , Humanos , Leucócitos/metabolismo , Pulmão , Masculino , Pessoa de Meia-Idade , Proteína 1 Complementadora Cruzada de Reparo de Raio-XRESUMO
4,5,6,7-Tetrabromo-1H-benzotriazole is widely used as the reference ATP-competitive inhibitor of protein kinase CK2. Herein, we study its new analogs: 5,6-diiodo- and 5,6-diiodo-4,7-dibromo-1H-benzotriazole. We used biophysical (MST, ITC) and biochemical (enzymatic assay) methods to describe the interactions of halogenated benzotriazoles with the catalytic subunit of human protein kinase CK2 (hCK2α). To trace the biological activity, we measured their cytotoxicity against four reference cancer cell lines and the effect on the mitochondrial inner membrane potential. The results obtained lead to the conclusion that iodinated compounds are an attractive alternative to brominated ones. One of them retains the cytotoxicity against selected cancer cell lines of the reference TBBt with a smaller side effect on mitochondrial activity. Both iodinated compounds are candidate leaders in the further development of CK2 inhibitors.
Assuntos
Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Triazóis/farmacologia , Biomarcadores , Relação Dose-Resposta a Droga , Humanos , Concentração Inibidora 50 , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Estrutura Molecular , Análise Espectral , Triazóis/química , Leveduras/efeitos dos fármacos , Leveduras/metabolismoRESUMO
Photodynamic therapy (PDT) is a clinically approved cancer therapy of low invasiveness. The therapeutic procedure involves administering a photosensitizing drug (PS), which is then activated with monochromatic light of a specific wavelength. The photochemical reaction produces highly toxic oxygen species. The development of resistance to PDT in some cancer cells is its main limitation. Several mechanisms are known to be involved in the development of cellular defense against cytotoxic effects of PDT, including activation of antioxidant enzymes, drug efflux pumps, degradation of PS, and overexpression of protein chaperons. Another putative factor that plays an important role in the development of resistance of cancer cells to PDT seems to be DNA repair; however, it has not been well studied so far. To explore the role of DNA repair and other potential novel mechanisms associated with the resistance to PDT in the glioblastoma cells, cells stably resistant to PDT were isolated from PDT sensitive cells following repetitive PDT cycles. Duly characterization of isolated PDT-resistant glioblastoma revealed that the resistance to PDT might be a consequence of several mechanisms, including higher repair efficiency of oxidative DNA damage and repair of DNA breaks. Higher activity of APE1 endonuclease and increased expression and activation of DNA damage kinase ATM was demonstrated in the U-87â¯MGR cell line, suggesting and proving that they are good targets for sensitization of resistant cells to PDT.
Assuntos
Dano ao DNA , Reparo do DNA , Resistencia a Medicamentos Antineoplásicos , Glioblastoma/tratamento farmacológico , Fotoquimioterapia , Linhagem Celular Tumoral , Ensaio Cometa , Quebras de DNA , DNA de Neoplasias/metabolismo , Glioblastoma/genética , Glioblastoma/fisiopatologia , Humanos , Estresse OxidativoRESUMO
Oxidative stress is involved in the pathogenesis of colon cancer. We wanted to elucidate at which stage of the disease this phenomenon occurs. In the examined groups of patients with colorectal cancer (CRC, n = 89), benign adenoma (AD, n = 77) and healthy volunteers (controls, n = 99), we measured: vitamins A, C and E in blood plasma, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanine (8-oxoGua) in leukocytes and urine, leukocyte 8-oxoGua excision activity, mRNA levels of APE1, OGG1, 8-oxo-7,8-dihydrodeoxyguanosine 5'-triphosphate pyrophosphohydrolase (MTH1) and OGG1 polymorphism. The vitamin levels decreased gradually in AD and CRC patients. 8-OxodG increased in leukocytes and urine of CRC and AD patients. 8-OxoGua was higher only in the urine of CRC patients. 8-OxoGua excision was higher in CRC patients than in controls, in spite of higher frequency of the OGG1 Cys326Cys genotype, encoding a glycosylase with decreased activity. mRNA levels of OGG1 and APE1 increased in CRC and AD patients, which could explain increased 8-oxoGua excision rate in CRC patients. MTH1 mRNA was also higher in CRC patients. The results suggest that oxidative stress occurs in CRC and AD individuals. This is accompanied by increased transcription of DNA repair genes, and increased 8-oxoGua excision rate in CRC patients, which is, however, insufficient to counteract the increased DNA damage.
Assuntos
Adenoma/metabolismo , Carcinoma/metabolismo , Neoplasias do Colo/metabolismo , Reparo do DNA/genética , Desoxiguanosina/análogos & derivados , Estresse Oxidativo/genética , 8-Hidroxi-2'-Desoxiguanosina , Adenoma/sangue , Adenoma/genética , Adenoma/urina , Pólipos Adenomatosos/sangue , Pólipos Adenomatosos/metabolismo , Adulto , Idoso , Envelhecimento/genética , Antioxidantes/metabolismo , Carcinoma/sangue , Carcinoma/genética , Carcinoma/urina , Estudos de Casos e Controles , Neoplasias do Colo/sangue , Neoplasias do Colo/genética , Neoplasias do Colo/urina , DNA Glicosilases/genética , DNA Glicosilases/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , DNA de Neoplasias/metabolismo , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Desoxiguanosina/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Monoéster Fosfórico Hidrolases/genética , Monoéster Fosfórico Hidrolases/metabolismo , Polimorfismo de Nucleotídeo Único/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Caracteres Sexuais , Fumar/efeitos adversos , Fumar/genéticaRESUMO
Professor Barbara Tudek received the Frits Sobels Award in 2019 from the European Environmental Mutagenesis and Genomics Society (EEMGS). This article presents her outstanding character and most important lines of research. The focus of her studies covered alkylative and oxidative damage to DNA bases, in particular mutagenic and carcinogenic properties of purines with an open imidazole ring and 8-oxo-7,8-dihydroguanine (8-oxoGua). They also included analysis of mutagenic properties and pathways for the repair of DNA adducts of lipid peroxidation (LPO) products arising in large quantities during inflammation. Professor Tudek did all of this in the hope of deciphering the mechanisms of DNA damage removal, in particular by the base excision repair (BER) pathway. Some lines of research aimed at discovering factors that can modulate the activity of DNA damage repair in hope to enhance existing anti-cancer therapies. The group's ongoing research aims at deciphering the resistance mechanisms of cancer cell lines acquired following prolonged exposure to photodynamic therapy (PDT) and the possibility of re-sensitizing cells to PDT in order to increase the application of this minimally invasive therapeutic method.
Assuntos
Carcinogênese/metabolismo , Reparo do DNA , Guanina/análogos & derivados , Neoplasias/história , Fotoquimioterapia/história , Radiossensibilizantes/uso terapêutico , Animais , Antineoplásicos/uso terapêutico , Biomarcadores Tumorais/metabolismo , Carcinogênese/genética , Carcinogênese/patologia , Linhagem Celular Tumoral , Adutos de DNA/química , Adutos de DNA/metabolismo , Dano ao DNA , Guanina/metabolismo , História do Século XX , História do Século XXI , Humanos , Peroxidação de Lipídeos , Neoplasias/tratamento farmacológico , Neoplasias/genética , Neoplasias/metabolismo , Fotoquimioterapia/métodosRESUMO
Cockayne syndrome complementation group B (CSB) protein is engaged in transcription-coupled repair (TCR) of UV induced DNA damage and its deficiency leads to progressive multisystem degeneration and premature aging. Here, we show that human CSB-deficient cells are hypersensitive to physiological concentrations (1-10 microM) of a lipid peroxidation product, trans-4-hydroxy-2-nonenal (HNE), and in response to HNE they develop a higher level of sister chromatid exchanges (SCEs) in comparison to the wild-type cells. HNE-DNA adducts block in vitro transcription by T7 RNA polymerase, as well as by HeLa cell-free extracts. Treatment of wild-type cells with 1-20 microM HNE causes dephosphorylation of the CSB protein, which stimulates its ATPase activity necessary for TCR. However, high HNE concentrations (100-200 microM) inhibit in vitro CSB ATPase activity as well as the transcription machinery in HeLa cell-free extracts. Cell lines expressing CSB protein mutated in different ATPase domains exhibit different sensitivities to HNE. The motif II mutant, which binds ATP, but is defective in ATP hydrolysis was as sensitive to HNE as CSB-null cells. In contrast, motif V mutant cells were as sensitive to HNE as were the cells bearing wild-type protein, while motif VI mutant cells showed intermediate sensitivity to HNE. These mutants exhibit decreased ATP binding, but retain residual ATPase activity. Homology modeling suggested that amino acids mutated in motifs II and VI are localized closer to the ATP binding site than amino acids mutated in ATPase motif V. These results suggest that HNE-DNA adducts are extremely toxic endogenous DNA lesion, and that their processing involves CSB. When these lesions are not removed from the transcribed DNA strand due to CSB gene mutation or CSB protein inactivation by high, pathological HNE concentrations, they may contribute to accelerated aging.
Assuntos
Aldeídos/metabolismo , Adutos de DNA/metabolismo , DNA Helicases/fisiologia , Enzimas Reparadoras do DNA/fisiologia , Aldeídos/farmacologia , Células HeLa , Humanos , Peroxidação de Lipídeos , Modelos Moleculares , Mutação , Fosforilação , Proteínas de Ligação a Poli-ADP-Ribose , Troca de Cromátide Irmã/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacosRESUMO
Lipid peroxidation (LPO) products are relatively stable and abundant metabolites, which accumulate in tissues of mammals with aging, being able to modify all cellular nucleophiles, creating protein and DNA adducts including crosslinks. Here, we used cells and mice deficient in the ERCC1-XPF endonuclease required for nucleotide excision repair and the repair of DNA interstrand crosslinks to ask if specifically LPO-induced DNA damage contributes to loss of cell and tissue homeostasis. Ercc1-/- mouse embryonic fibroblasts were more sensitive than wild-type (WT) cells to the LPO products: 4-hydroxy-2-nonenal (HNE), crotonaldehyde and malondialdehyde. ERCC1-XPF hypomorphic mice were hypersensitive to CCl4 and a diet rich in polyunsaturated fatty acids, two potent inducers of endogenous LPO. To gain insight into the mechanism of how LPO influences DNA repair-deficient cells, we measured the impact of the major endogenous LPO product, HNE, on WT and Ercc1-/- cells. HNE inhibited proliferation, stimulated ROS and LPO formation, induced DNA base damage, strand breaks, error-prone translesion DNA synthesis and cellular senescence much more potently in Ercc1-/- cells than in DNA repair-competent control cells. HNE also deregulated base excision repair and energy production pathways. Our observations that ERCC1-deficient cells and mice are hypersensitive to LPO implicates LPO-induced DNA damage in contributing to cellular demise and tissue degeneration, notably even when the source of LPO is dietary polyunsaturated fats.
Assuntos
Senescência Celular , Dano ao DNA , Reparo do DNA , Proteínas de Ligação a DNA/fisiologia , Endonucleases/fisiologia , Peroxidação de Lipídeos , Estresse Oxidativo , Animais , Proliferação de Células , Camundongos , Camundongos Knockout , Espécies Reativas de Oxigênio/metabolismoRESUMO
Base excision repair (BER) pathway executed by a complex network of proteins is the major system responsible for the removal of damaged DNA bases and repair of DNA single strand breaks (SSBs) generated by environmental agents, such as certain cancer therapies, or arising spontaneously during cellular metabolism. Both modified DNA bases and SSBs with ends other than 3'-OH and 5'-P are repaired either by replacement of a single or of more nucleotides in the processes called short-patch BER (SP-BER) or long-patch BER (LP-BER), respectively. In contrast to Escherichia coli cells, in human ones, the two BER sub-pathways are operated by different sets of proteins. In this review the selection between SP- and LP-BER and mutations in BER and end-processors genes and their contribution to bacterial mutagenesis and human diseases are considered.
Assuntos
Proteínas de Bactérias/genética , Reparo do DNA/genética , Mutação , Animais , Proteínas de Bactérias/metabolismo , Dano ao DNA , Humanos , Modelos BiológicosRESUMO
Exocyclic adducts to DNA bases are formed as a consequence of exposure to certain environmental carcinogens as well as inflammation and lipid peroxidation (LPO). Complex family of LPO products gives rise to a variety of DNA adducts, which can be grouped in two classes: (i) small etheno-type adducts of strong mutagenic potential, and (ii) bulky, propano-type adducts, which block replication and transcription, and are lethal lesions. Etheno-DNA adducts are removed from the DNA by base excision repair (BER), AlkB and nucleotide incision repair enzymes (NIR), while substituted propano-type lesions by nucleotide excision repair (NER) and homologous recombination (HR). Changes of the level and activity of several enzymes removing exocyclic adducts from the DNA was reported during carcinogenesis. Also several beyond repair functions of these enzymes, which participate in regulation of cell proliferation and growth, as well as RNA processing was recently described. In addition, adducts of LPO products to proteins was reported during aging and age-related diseases. The paper summarizes pathways for exocyclic adducts removal and describes how proteins involved in repair of these adducts can modify pathological states of the organism.
Assuntos
Adutos de DNA/metabolismo , Dano ao DNA , DNA Glicosilases/metabolismo , Reparo do DNA , Peroxidação de Lipídeos , Envelhecimento , Animais , Carcinogênese , Adutos de DNA/química , Recombinação Homóloga , Humanos , Mutagênese , OxirreduçãoRESUMO
To assess the role of oxidative stress and lipid peroxidation (LPO) in the pathogenesis of lung cancer, we measured the levels of 1,N(6)-ethenoadenine (epsilonA) and 3,N(4)-ethenocytosine (epsilonC) in the DNA by immunoaffinity/(32)P postlabeling (33 cases). We also measured the capacity for epsilonA and epsilonC repair (by the nicking assay) in normal and tumor lung tissues, as well as in blood leukocytes of lung cancer patients (56 cases). Repair activities for epsilonA and epsilonC were also assayed in leukocytes of healthy volunteers, matched with cancer patients for age, sex, and smoking habit (25 individuals). Up to 10-fold variations among individuals were observed both in adducts level and repair activities. No differences in epsilonA and epsilonC levels between tumor and nonaffected lung tissues were recorded. However, leukocytes accumulated a significantly higher number of DNA adducts than the lung tissues. Repair activities for both epsilonA and epsilonC were significantly higher in tumor than in normal lung tissue. No significant differences in epsilonA and epsilonC repair activities were associated with age, sex, or smoking habit. However, a significant difference in repair capacity was observed between two histological types of lung cancer, squamous cell carcinoma (SQ) and adenocarcinoma (AD). In individuals suffering from lung AD, epsilonA- and epsilonC-repair activities in normal lung and blood leukocytes were significantly lower than in SQ patients. Moreover, in nonaffected lung tissue of AD patients, the ratio epsilonA/epsilonC adducts was lower than in SQ patients. Differences have also been found between epsilonA and epsilonC repair activities of cancer patients and healthy volunteers. Repair capacity for epsilonA was significantly lower in blood leukocytes of lung cancer patients than in leukocytes of healthy volunteers (P = 0.012). This difference was even larger between healthy volunteers and patients developing inflammation-related AD (P = 0.00033). Repair activities for epsilonC were the same in leukocytes of healthy controls, all lung cancer patients, and SQ patients. However, individuals with ADs revealed significantly lower epsilonC-repair activity (P = 0.013). These results suggest that oxidative stress-mediated lipid peroxidation might contribute to induction and/or progression of lung cancer. Decreased activity of base excision repair pathway for epsilonA and epsilonC is associated particularly with inflammation-related lung AD.
Assuntos
Adenina/análogos & derivados , Adenina/metabolismo , Adenocarcinoma/genética , Citosina/análogos & derivados , Citosina/metabolismo , Reparo do DNA , Neoplasias Pulmonares/genética , Adenocarcinoma/metabolismo , Adulto , Fatores Etários , Idoso , Adutos de DNA/metabolismo , DNA de Neoplasias/genética , DNA de Neoplasias/metabolismo , Feminino , Humanos , Leucócitos/metabolismo , Pulmão/metabolismo , Neoplasias Pulmonares/metabolismo , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Fumar/genética , Fumar/metabolismoRESUMO
The broad spectrum of oxidative DNA damage biomarkers [urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) and 8-hydroxyguanine (8-OH-Gua)] and the level of oxidative DNA damage and repair in leukocytes DNA were analyzed in three groups of subjects: (a) lung cancer patients [all smokers (n = 51)]; (b) healthy smokers with comparable smoking status (n = 26); and (c) healthy nonsmokers (n = 38). The mean level of 8-OH-Gua in urine samples of 38 healthy nonsmokers reached a value of 1.783 +/- 0.785 nmol/day/kg. This level was significantly lower than that in the urine of the two smoker groups (cancer patients and healthy smokers), in whom the levels reached values of 2.319 +/- 1.271 and 2.824 +/- 0.892 nmol/day/kg, respectively. Urinary excretion of 8-OH-dGuo was similar in all groups of subjects. The level of 8-OH-dGuo in DNA isolated from leukocytes of cancer patients was significantly higher than that in DNA isolated from the group of healthy smokers and nonsmokers (9.44 +/- 4.77 versus 7.20 +/- 2.83 and 5.88 +/- 2.47 molecules/10(6) deoxyguanosine, respectively). Repair activity of 8-OH-Gua, as estimated by the nicking assay, was significantly higher in blood leukocytes of healthy volunteers (44.6 +/- 20.21 and 37.54 +/- 13.43 pmol/h/mg protein for smokers and nonsmokers, respectively) than in the leukocytes of lung cancer patients (24.56 +/- 11.28 pmol/h/mg protein). Because oxidative DNA insult represented by urinary excretion of oxidative DNA lesions was similar in both groups of subjects with similar smoking status, it appears likely that a higher rate of generation of oxidative damage in cellular DNA of lung cancer patients is a result of deficiency of the repair mechanism(s) in this group.
Assuntos
Dano ao DNA , Reparo do DNA , Desoxiguanosina/análogos & derivados , Predisposição Genética para Doença , Neoplasias Pulmonares/genética , 8-Hidroxi-2'-Desoxiguanosina , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores , Desoxiguanosina/análise , Feminino , Humanos , Neoplasias Pulmonares/etiologia , Masculino , Pessoa de Meia-Idade , Oxirredução , Estresse OxidativoRESUMO
DNA base analogs, 2,4,5,6-substituted pyrimidines and 2,6-substituted purines were tested as potential inhibitors of E. coli Fpg protein (formamidopyrimidine -DNA glycosylase). Three of the seventeen compounds tested revealed inhibitory properties. 2-Thioxanthine was the most efficient, inhibiting 50% of 2,6-diamino-4-hydroxy-5N-methyl-formamidopyrimidine (Fapy-7MeG) excision activity at 17.1 microM concentration. The measured K(i) was 4.44 +/- 0.15 microM. Inhibition was observed only when the Fpg protein was first challenged to its substrate followed by the addition of the base analog, suggesting uncompetitive (catalytic) inhibition. For two other compounds, 2-thio- or 2-oxo-4,5,6-substituted pyrimidines, IC(50) was only 343.3 +/- 58.6 and 350 +/- 24.4 microM, respectively. No change of the Fpg glycosylase activity was detected in the presence of Fapy-7MeG, up to 5 microM. We also investigated the effect of DNA structure modified by tryptophan pyrolysate (Trp-P-1) on the activity of base excision repair enzymes: Escherichia coli and human DNA glycosylases of oxidized (Fpg, Nth) and alkylated bases (TagA, AlkA, and ANPG), and for bacterial AP endonuclease (Xth protein). Trp-P-1, which changes the secondary DNA structure into non-B, non-Z most efficiently inhibited excision of alkylated bases by the AlkA glycosylase (IC(50) = 1 microM). The ANPG, TagA, and Fpg proteins were also inhibited although to a lesser extent (IC(50) = 76.5 microM, 96 microM, and 187.5 microM, respectively). Trp-P-1 also inhibited incision of DNA at abasic sites by the beta-lyase activity of the Fpg and Nth proteins, and to a lesser extent by the Xth AP endonuclease. Thus, DNA conformation is critical for excision of damaged bases and incision of abasic sites by DNA repair enzymes.