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1.
Nat Commun ; 11(1): 3883, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32753598

RESUMO

Temozolomide (TMZ) is an oral alkylating agent used for the treatment of glioblastoma and is now becoming a chemotherapeutic option in patients diagnosed with high-risk low-grade gliomas. The O-6-methylguanine-DNA methyltransferase (MGMT) is responsible for the direct repair of the main TMZ-induced toxic DNA adduct, the O6-Methylguanine lesion. MGMT promoter hypermethylation is currently the only known biomarker for TMZ response in glioblastoma patients. Here we show that a subset of recurrent gliomas carries MGMT genomic rearrangements that lead to MGMT overexpression, independently from changes in its promoter methylation. By leveraging the CRISPR/Cas9 technology we generated some of these MGMT rearrangements in glioma cells and demonstrated that the MGMT genomic rearrangements contribute to TMZ resistance both in vitro and in vivo. Lastly, we showed that such fusions can be detected in tumor-derived exosomes and could potentially represent an early detection marker of tumor recurrence in a subset of patients treated with TMZ.


Assuntos
Neoplasias Encefálicas/tratamento farmacológico , Metilases de Modificação do DNA/genética , Enzimas Reparadoras do DNA/genética , Resistencia a Medicamentos Antineoplásicos/genética , Rearranjo Gênico , Glioma/tratamento farmacológico , Recidiva Local de Neoplasia/genética , Temozolomida/farmacologia , Proteínas Supressoras de Tumor/genética , Adolescente , Adulto , Idoso , Animais , Neoplasias Encefálicas/genética , Linhagem Celular Tumoral , Adutos de DNA/efeitos dos fármacos , Adutos de DNA/metabolismo , Metilação de DNA , Metilases de Modificação do DNA/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Glioma/genética , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/prevenção & controle , Regiões Promotoras Genéticas/genética , RNA-Seq , Temozolomida/uso terapêutico , Proteínas Supressoras de Tumor/metabolismo , Regulação para Cima , Sequenciamento Completo do Genoma , Ensaios Antitumorais Modelo de Xenoenxerto , Adulto Jovem
2.
Medicine (Baltimore) ; 99(24): e20554, 2020 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-32541478

RESUMO

Colorectal cancer (CRC) represents a major malignancy globally, with microsatellite instability as its second top molecular mechanism of carcinogenesis. Immunohistochemical (IHC), whose sensitivity and specificity exceed 90%, is used routinely to detect 4 MMR proteins (MLH1, PMS2, MSH2, and MSH6) for screening mismatch repair system defects. We aimed to assess associations of clinicopathologic characteristics with MMR status in resectable CRC patients.Stage I-III CRC cases administered surgical resection in Zhejiang Cancer Hospital in 2013 to 2015 were retrospectively analyzed. MLH1, MSH2, MSH6, and PMS2 protein amounts were evaluated immunohistochemically. Clinicopathological information, including age, sex, tumor location, histological subclass, disease stage, regional lymph node (LN) metastasis, American Joint Committee on Cancer (AJCC) 8th edition stage, and survival data were retrospectively reviewed.A total of 133 CRC cases were assessed, including 74 (55.6%), 45 (33.8%), 55 (41.4%), and 77 (57.9%) not expressing MLH1, MSH2, MSH6, and PMS2, respectively. There were significant associations of MLH1, MSH2, MSH6, and PMS2 proteins with age and sex (P < .05). MLH1, MSH2, and MSH6 (but not PMS2) showed positive associations with primary tumor location (P < .05). Of the 133 patients, 70 and 63 cases were affected on the right and left sides, respectively; significant associations of primary site with age and sex were observed (P < .05). Regarding the MMR status, MLH1, MSH2, and MSH6 protein expression levels were positively associated with primary site (P < .05). Five-year overall survival (OS) rates were 84.2% and 79.2% in left-side and right-side cases, respectively; 5-year disease-free survival (DFS) rates were 74.0% and 69.8%, respectively. Survival had no differences between left- and right-side patients in terms of OS (P = .318) and DFS (P = .481).These data demonstrate that 4 major dMMR proteins are expressed differently in left- and right-side CRCs, and survival is comparable in right- and left-side resectable CRC cases with dMMR.


Assuntos
Adenocarcinoma/genética , Neoplasias Colorretais/genética , Reparo de Erro de Pareamento de DNA , Enzimas Reparadoras do DNA/metabolismo , Adenocarcinoma/metabolismo , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , China/epidemiologia , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Proteínas de Ligação a DNA/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Endonuclease PMS2 de Reparo de Erro de Pareamento/metabolismo , Proteína 1 Homóloga a MutL/metabolismo , Proteína 2 Homóloga a MutS/metabolismo , Estudos Retrospectivos , Adulto Jovem
3.
Nat Commun ; 11(1): 2104, 2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32355176

RESUMO

The response to DNA damage-stalled RNA polymerase II (RNAPIIo) involves the assembly of the transcription-coupled repair (TCR) complex on actively transcribed strands. The function of the TCR proteins CSB, CSA and UVSSA and the manner in which the core DNA repair complex, including transcription factor IIH (TFIIH), is recruited are largely unknown. Here, we define the assembly mechanism of the TCR complex in human isogenic knockout cells. We show that TCR is initiated by RNAPIIo-bound CSB, which recruits CSA through a newly identified CSA-interaction motif (CIM). Once recruited, CSA facilitates the association of UVSSA with stalled RNAPIIo. Importantly, we find that UVSSA is the key factor that recruits the TFIIH complex in a manner that is stimulated by CSB and CSA. Together these findings identify a sequential and highly cooperative assembly mechanism of TCR proteins and reveal the mechanism for TFIIH recruitment to DNA damage-stalled RNAPIIo to initiate repair.


Assuntos
Proteínas de Transporte/metabolismo , Dano ao DNA , DNA Helicases/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , RNA Polimerase II/metabolismo , Fator de Transcrição TFIIH/metabolismo , Fatores de Transcrição/metabolismo , Animais , Linhagem Celular Tumoral , Reparo do DNA , Humanos , Transcrição Genética , Raios Ultravioleta , Xenopus laevis
4.
Brain Tumor Pathol ; 37(2): 50-59, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32361941

RESUMO

Aging is a known negative prognostic factor in glioblastomas (GBM). Whether particular genetic backgrounds are a factor in poor outcomes of elderly patients with GBM warrants investigation. We aim to elucidate any differences between older and younger adult patients with IDH-wildtype GBM regarding both molecular characteristics and clinical outcomes. We collected adult cases diagnosed with IDH-wildtype GBM from the Kansai Network. Clinical and pathological characteristics were analyzed retrospectively and compared between older (≥ 70 years) and younger (≤ 50 years) cases. Included were 92 older vs. 33 younger cases. The older group included more patients with preoperative Karnofsky performance status score < 70 and had a shorter survival time than the younger group. MGMT promoter was methylated more frequently in the older group. TERT promoter mutation was more common in the older group. There were significant differences in DNA copy-number alteration profiles between age groups in PTEN deletion and CDK4 amplification/gain. In the older group, no molecular markers were identified, but surgical resection was an independent prognostic factor. Age-specific survival difference was significant in the MGMT methylated and TERT wildtype subgroup. Elderly patients have several potential factors in poor prognosis of glioblastomas. Varying molecular profiles may explain differing rates of survival between generations.


Assuntos
Neoplasias Encefálicas/genética , Glioblastoma/genética , Isocitrato Desidrogenase/genética , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Neoplasias Encefálicas/mortalidade , Estudos de Coortes , Metilases de Modificação do DNA/genética , Metilases de Modificação do DNA/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Feminino , Glioblastoma/mortalidade , Humanos , Japão , Masculino , Metilação , Pessoa de Meia-Idade , Prognóstico , Taxa de Sobrevida , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo
5.
Nucleic Acids Res ; 48(9): 4960-4975, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32232411

RESUMO

G-quadruplexes represent unique roadblocks to DNA replication, which tends to stall at these secondary structures. Although G-quadruplexes can be found throughout the genome, telomeres, due to their G-richness, are particularly predisposed to forming these structures and thus represent difficult-to-replicate regions. Here, we demonstrate that exonuclease 1 (EXO1) plays a key role in the resolution of, and replication through, telomeric G-quadruplexes. When replication forks encounter G-quadruplexes, EXO1 resects the nascent DNA proximal to these structures to facilitate fork progression and faithful replication. In the absence of EXO1, forks accumulate at stabilized G-quadruplexes and ultimately collapse. These collapsed forks are preferentially repaired via error-prone end joining as depletion of EXO1 diverts repair away from error-free homology-dependent repair. Such aberrant repair leads to increased genomic instability, which is exacerbated at chromosome termini in the form of dysfunction and telomere loss.


Assuntos
Enzimas Reparadoras do DNA/fisiologia , Replicação do DNA , Exodesoxirribonucleases/fisiologia , Quadruplex G , Telômero/química , Aminoquinolinas/farmacologia , Linhagem Celular , Reparo do DNA por Junção de Extremidades , Reparo do DNA , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Exodesoxirribonucleases/genética , Exodesoxirribonucleases/metabolismo , Quadruplex G/efeitos dos fármacos , Técnicas de Inativação de Genes , Células HeLa , Humanos , Neoplasias/metabolismo , Neoplasias/mortalidade , Ácidos Picolínicos/farmacologia , Prognóstico
6.
PLoS One ; 15(3): e0230492, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32218600

RESUMO

BACKGROUND: Temozolomide (TMZ) has been the standard-of-care chemotherapy for glioblastoma (GBM) patients for more than a decade. Despite this long time in use, significant questions remain regarding how best to optimize TMZ therapy for individual patients. Understanding the relationship between TMZ response and factors such as number of adjuvant TMZ cycles, patient age, patient sex, and image-based tumor features, might help predict which GBM patients would benefit most from TMZ, particularly for those whose tumors lack O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation. METHODS AND FINDINGS: Using a cohort of 90 newly-diagnosed GBM patients treated according to the standard of care, we examined the relationships between several patient and tumor characteristics and volumetric and survival outcomes during adjuvant chemotherapy. Volumetric changes in MR imaging abnormalities during adjuvant therapy were used to assess TMZ response. T1Gd volumetric response is associated with younger patient age, increased number of TMZ cycles, longer time to nadir volume, and decreased tumor invasiveness. Moreover, increased adjuvant TMZ cycles corresponded with improved volumetric response only among more nodular tumors, and this volumetric response was associated with improved survival outcomes. Finally, in a subcohort of patients with known MGMT methylation status, methylated tumors were more diffusely invasive than unmethylated tumors, suggesting the improved response in nodular tumors is not driven by a preponderance of MGMT methylated tumors. CONCLUSIONS: Our finding that less diffusely invasive tumors are associated with greater volumetric response to TMZ suggests patients with these tumors may benefit from additional adjuvant TMZ cycles, even for those without MGMT methylation.


Assuntos
Neoplasias Encefálicas , Metilação de DNA/efeitos dos fármacos , Metilases de Modificação do DNA/metabolismo , Enzimas Reparadoras do DNA/metabolismo , DNA de Neoplasias/metabolismo , Glioblastoma , Imagem por Ressonância Magnética , Regiões Promotoras Genéticas , Temozolomida/administração & dosagem , Proteínas Supressoras de Tumor/metabolismo , Adolescente , Adulto , Fatores Etários , Idoso , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/metabolismo , Feminino , Glioblastoma/diagnóstico por imagem , Glioblastoma/tratamento farmacológico , Glioblastoma/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica
7.
Nat Commun ; 11(1): 1478, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198374

RESUMO

The Escherichia coli transcription-repair coupling factor Mfd displaces stalled RNA polymerase and delivers the stall site to the nucleotide excision repair factors UvrAB for damage detection. Whether this handoff from RNA polymerase to UvrA occurs via the Mfd-UvrA2-UvrB complex or alternate reaction intermediates in cells remains unclear. Here, we visualise Mfd in actively growing cells and determine the catalytic requirements for faithful recruitment of nucleotide excision repair proteins. We find that ATP hydrolysis by UvrA governs formation and disassembly of the Mfd-UvrA2 complex. Further, Mfd-UvrA2-UvrB complexes formed by UvrB mutants deficient in DNA loading and damage recognition are impaired in successful handoff. Our single-molecule dissection of interactions of Mfd with its partner proteins inside live cells shows that the dissociation of Mfd is tightly coupled to successful loading of UvrB, providing a mechanism via which loading of UvrB occurs in a strand-specific manner.


Assuntos
Enzimas Reparadoras do DNA/metabolismo , Reparo do DNA/fisiologia , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Imagem Individual de Molécula/métodos , Fatores de Transcrição/metabolismo , Adenosina Trifosfatases , Proteínas de Bactérias , ATPases Bacterianas Próton-Translocadoras , DNA Helicases/genética , DNA Helicases/metabolismo , Proteínas de Ligação a DNA , RNA Polimerases Dirigidas por DNA/metabolismo , Escherichia coli/enzimologia , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Modelos Moleculares , Complexos Multienzimáticos/metabolismo , Conformação Proteica , Dedos de Zinco/genética , Dedos de Zinco/fisiologia
8.
Cell ; 180(6): 1228-1244.e24, 2020 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-32142649

RESUMO

Transcription-coupled nucleotide excision repair (TC-NER) is initiated by the stalling of elongating RNA polymerase II (RNAPIIo) at DNA lesions. The ubiquitination of RNAPIIo in response to DNA damage is an evolutionarily conserved event, but its function in mammals is unknown. Here, we identified a single DNA damage-induced ubiquitination site in RNAPII at RPB1-K1268, which regulates transcription recovery and DNA damage resistance. Mechanistically, RPB1-K1268 ubiquitination stimulates the association of the core-TFIIH complex with stalled RNAPIIo through a transfer mechanism that also involves UVSSA-K414 ubiquitination. We developed a strand-specific ChIP-seq method, which revealed RPB1-K1268 ubiquitination is important for repair and the resolution of transcriptional bottlenecks at DNA lesions. Finally, RPB1-K1268R knockin mice displayed a short life-span, premature aging, and neurodegeneration. Our results reveal RNAPII ubiquitination provides a two-tier protection mechanism by activating TC-NER and, in parallel, the processing of DNA damage-stalled RNAPIIo, which together prevent prolonged transcription arrest and protect against neurodegeneration.


Assuntos
Reparo do DNA/fisiologia , RNA Polimerase II/metabolismo , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , DNA/metabolismo , Dano ao DNA/fisiologia , DNA Helicases/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Feminino , Células HCT116 , Células HEK293 , Células HeLa , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , RNA Polimerase II/genética , Ubiquitinação
9.
Proc Natl Acad Sci U S A ; 117(14): 8154-8165, 2020 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-32205441

RESUMO

Spinocerebellar ataxia type 3 (SCA3) is a dominantly inherited neurodegenerative disease caused by CAG (encoding glutamine) repeat expansion in the Ataxin-3 (ATXN3) gene. We have shown previously that ATXN3-depleted or pathogenic ATXN3-expressing cells abrogate polynucleotide kinase 3'-phosphatase (PNKP) activity. Here, we report that ATXN3 associates with RNA polymerase II (RNAP II) and the classical nonhomologous end-joining (C-NHEJ) proteins, including PNKP, along with nascent RNAs under physiological conditions. Notably, ATXN3 depletion significantly decreased global transcription, repair of transcribed genes, and error-free double-strand break repair of a 3'-phosphate-containing terminally gapped, linearized reporter plasmid. The missing sequence at the terminal break site was restored in the recircularized plasmid in control cells by using the endogenous homologous transcript as a template, indicating ATXN3's role in PNKP-mediated error-free C-NHEJ. Furthermore, brain extracts from SCA3 patients and mice show significantly lower PNKP activity, elevated p53BP1 level, more abundant strand-breaks in the transcribed genes, and degradation of RNAP II relative to controls. A similar RNAP II degradation is also evident in mutant ATXN3-expressing Drosophila larval brains and eyes. Importantly, SCA3 phenotype in Drosophila was completely amenable to PNKP complementation. Hence, salvaging PNKP's activity can be a promising therapeutic strategy for SCA3.


Assuntos
Ataxina-3/genética , Reparo do DNA por Junção de Extremidades , Enzimas Reparadoras do DNA/metabolismo , Doença de Machado-Joseph/genética , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , RNA Polimerase II/metabolismo , Proteínas Repressoras/genética , Idoso de 80 Anos ou mais , Animais , Animais Geneticamente Modificados , Ataxina-3/metabolismo , Encéfalo/patologia , Linhagem Celular , Quebras de DNA de Cadeia Dupla , Modelos Animais de Doenças , Drosophila , Feminino , Técnicas de Silenciamento de Genes , Humanos , Células-Tronco Pluripotentes Induzidas , Doença de Machado-Joseph/metabolismo , Doença de Machado-Joseph/patologia , Masculino , Camundongos , Pessoa de Meia-Idade , Mutação , Peptídeos/genética , RNA Interferente Pequeno/metabolismo
10.
Nature ; 578(7794): 296-300, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32025036

RESUMO

The proteasome is a major proteolytic machine that regulates cellular proteostasis through selective degradation of ubiquitylated proteins1,2. A number of ubiquitin-related molecules have recently been found to be involved in the regulation of biomolecular condensates or membraneless organelles, which arise by liquid-liquid phase separation of specific biomolecules, including stress granules, nuclear speckles and autophagosomes3-8, but it remains unclear whether the proteasome also participates in such regulation. Here we reveal that proteasome-containing nuclear foci form under acute hyperosmotic stress. These foci are transient structures that contain ubiquitylated proteins, p97 (also known as valosin-containing protein (VCP)) and multiple proteasome-interacting proteins, which collectively constitute a proteolytic centre. The major substrates for degradation by these foci were ribosomal proteins that failed to properly assemble. Notably, the proteasome foci exhibited properties of liquid droplets. RAD23B, a substrate-shuttling factor for the proteasome, and ubiquitylated proteins were necessary for formation of proteasome foci. In mechanistic terms, a liquid-liquid phase separation was triggered by multivalent interactions of two ubiquitin-associated domains of RAD23B and ubiquitin chains consisting of four or more ubiquitin molecules. Collectively, our results suggest that ubiquitin-chain-dependent phase separation induces the formation of a nuclear proteolytic compartment that promotes proteasomal degradation.


Assuntos
Complexo de Endopeptidases do Proteassoma/química , Complexo de Endopeptidases do Proteassoma/metabolismo , Estresse Fisiológico , Ubiquitinação , Linhagem Celular , Núcleo Celular/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Humanos , Pressão Osmótica , Poliubiquitina/metabolismo , Proteólise , Proteostase , Proteínas Ribossômicas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Proteína com Valosina/metabolismo
11.
Nat Commun ; 11(1): 857, 2020 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-32051414

RESUMO

Meiotic recombination is initiated by SPO11-induced double-strand breaks (DSBs). In most mammals, the methyltransferase PRDM9 guides SPO11 targeting, and the ATM kinase controls meiotic DSB numbers. Following MRE11 nuclease removal of SPO11, the DSB is resected and loaded with DMC1 filaments for homolog invasion. Here, we demonstrate the direct detection of meiotic DSBs and resection using END-seq on mouse spermatocytes with low sample input. We find that DMC1 limits both minimum and maximum resection lengths, whereas 53BP1, BRCA1 and EXO1 play surprisingly minimal roles. Through enzymatic modifications to END-seq, we identify a SPO11-bound meiotic recombination intermediate (SPO11-RI) present at all hotspots. We propose that SPO11-RI forms because chromatin-bound PRDM9 asymmetrically blocks MRE11 from releasing SPO11. In Atm-/- spermatocytes, trapped SPO11 cleavage complexes accumulate due to defective MRE11 initiation of resection. Thus, in addition to governing SPO11 breakage, ATM and PRDM9 are critical local regulators of mammalian SPO11 processing.


Assuntos
Endodesoxirribonucleases/metabolismo , Histona-Lisina N-Metiltransferase/metabolismo , Recombinação Homóloga/fisiologia , Meiose/fisiologia , Espermatócitos/metabolismo , Animais , Proteínas Mutadas de Ataxia Telangiectasia/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Cromatina , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Endodesoxirribonucleases/genética , Exodesoxirribonucleases/genética , Exodesoxirribonucleases/metabolismo , Feminino , Histona-Lisina N-Metiltransferase/genética , Proteína Homóloga a MRE11/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas de Ligação a Fosfato/genética , Proteínas de Ligação a Fosfato/metabolismo , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/genética
12.
Toxicology ; 435: 152413, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-32109525

RESUMO

DNA interstrand cross-links (ICLs) are essential for the antitumor activity of chloroethylnitrosoureas (CENUs). Commonly, CENUs resistance is mainly considered to be associated with O6-methylguanine-DNA methyltransferase (MGMT) within tumors. Bypassing the MGMT-mediated resistance, to our knowledge, herein, we first utilized a novel glycolytic inhibitor, 3-bromopyruvate (3-BrPA), to increase the cytotoxic effects of l,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) to human glioma cells based on the hypothesis that blocking energy metabolism renders tumor cells more sensitive to chemotherapy. We found 3-BrPA significantly increased the cell killing by BCNU in human glioma SF763 and SF126 cell lines. Significantly decreased levels of extracellular lactate, cellular ATP and glutathione (GSH) were observed after 3-BrPA treatment, and the effects were more remarkable with 3-BrPA in combination with BCNU. Considering that the role of ATP and GSH in drug efflux, DNA damage repair and drug inactivation, we determined the effect of 3-BrPA on the formation of dG-dC ICLs induced by BCNU using stable isotope dilution high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). As expected, the levels of lethal dG-dC ICLs induced by BCNU were obviously enhanced after 3-BrPA pretreatment. Based on these results, 3-BrPA and related glycolytic inhibitors may be promising to enhance the cell killing effect and reverse the clinical chemoresistance of CENUs and related antitumor agents.


Assuntos
Antineoplásicos Alquilantes/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Carmustina/farmacologia , Dano ao DNA , Glioma/tratamento farmacológico , Glicólise/efeitos dos fármacos , Piruvatos/farmacologia , Trifosfato de Adenosina/metabolismo , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Metilases de Modificação do DNA/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Resistência a Medicamentos , Glioma/metabolismo , Glioma/patologia , Glutationa/metabolismo , Humanos , O(6)-Metilguanina-DNA Metiltransferase/metabolismo , Proteínas Supressoras de Tumor/metabolismo
13.
Nucleic Acids Res ; 48(5): 2473-2485, 2020 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-31970402

RESUMO

Cockayne Syndrome (CS) is a rare neurodegenerative disease characterized by short stature, accelerated aging and short lifespan. Mutations in two human genes, ERCC8/CSA and ERCC6/CSB, are causative for CS and their protein products, CSA and CSB, while structurally unrelated, play roles in DNA repair and other aspects of DNA metabolism in human cells. Many clinical and molecular features of CS remain poorly understood, and it was observed that CSA and CSB regulate transcription of ribosomal DNA (rDNA) genes and ribosome biogenesis. Here, we investigate the dysregulation of rRNA synthesis in CS. We report that Nucleolin (Ncl), a nucleolar protein that regulates rRNA synthesis and ribosome biogenesis, interacts with CSA and CSB. In addition, CSA induces ubiquitination of Ncl, enhances binding of CSB to Ncl, and CSA and CSB both stimulate the binding of Ncl to rDNA and subsequent rRNA synthesis. CSB and CSA also increase RNA Polymerase I loading to the coding region of the rDNA and this is Ncl dependent. These findings suggest that CSA and CSB are positive regulators of rRNA synthesis via Ncl regulation. Most CS patients carry mutations in CSA and CSB and present with similar clinical features, thus our findings provide novel insights into disease mechanism.


Assuntos
Síndrome de Cockayne/genética , DNA Helicases/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Regulação da Expressão Gênica , Fosfoproteínas/genética , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , RNA Ribossômico/genética , Proteínas de Ligação a RNA/genética , Fatores de Transcrição/metabolismo , Transcrição Genética , Linhagem Celular , DNA Ribossômico/genética , Humanos , Modelos Biológicos , Fosfoproteínas/metabolismo , Ligação Proteica , Proteínas de Ligação a RNA/metabolismo
14.
J Cancer Res Clin Oncol ; 146(2): 343-356, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31932908

RESUMO

PURPOSE: We set out to determine whether clinically tested epigenetic drugs against class I histone deacetylases (HDACs) affect hallmarks of the metastatic process. METHODS: We treated permanent and primary renal, lung, and breast cancer cells with the class I histone deacetylase inhibitors (HDACi) entinostat (MS-275) and valproic acid (VPA), the replicative stress inducer hydroxyurea (HU), the DNA-damaging agent cis-platinum (L-OHP), and the cytokine transforming growth factor-ß (TGFß). We used proteomics, quantitative PCR, immunoblot, single cell DNA damage assays, and flow cytometry to analyze cell fate after drug exposure. RESULTS: We show that HDACi interfere with DNA repair protein expression and trigger DNA damage and apoptosis alone and in combination with established chemotherapeutics. Furthermore, HDACi disrupt the balance of cell adhesion protein expression and abrogate TGFß-induced cellular plasticity of transformed cells. CONCLUSION: HDACi suppress the epithelial-mesenchymal transition (EMT) and compromise the DNA integrity of cancer cells. These data encourage further testing of HDACi against tumor cells.


Assuntos
Reparo do DNA/fisiologia , Proteínas de Ligação a DNA/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Neoplasias/tratamento farmacológico , Animais , Benzamidas/farmacologia , Plasticidade Celular/efeitos dos fármacos , Cisplatino/farmacologia , Enzimas Reparadoras do DNA/metabolismo , Resistencia a Medicamentos Antineoplásicos , Humanos , Hidroxiureia/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Metástase Neoplásica , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Piridinas/farmacologia , Fator de Crescimento Transformador beta/farmacologia , Ácido Valproico/farmacologia
15.
Nat Commun ; 11(1): 236, 2020 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-31932649

RESUMO

Alternative DNA structure-forming sequences can stimulate mutagenesis and are enriched at mutation hotspots in human cancer genomes, implicating them in disease etiology. However, the mechanisms involved are not well characterized. Here, we discover that Z-DNA is mutagenic in yeast as well as human cells, and that the nucleotide excision repair complex, Rad10-Rad1(ERCC1-XPF), and the mismatch repair complex, Msh2-Msh3, are required for Z-DNA-induced genetic instability in yeast and human cells. Both ERCC1-XPF and MSH2-MSH3 bind to Z-DNA-forming sequences, though ERCC1-XPF recruitment to Z-DNA is dependent on MSH2-MSH3. Moreover, ERCC1-XPF-dependent DNA strand-breaks occur near the Z-DNA-forming region in human cell extracts, and we model these interactions at the sub-molecular level. We propose a relationship in which these complexes recognize and process Z-DNA in eukaryotes, representing a mechanism of Z-DNA-induced genomic instability.


Assuntos
Enzimas Reparadoras do DNA/metabolismo , Reparo do DNA , Proteínas de Ligação a DNA/metabolismo , DNA/química , Instabilidade Genômica , Linhagem Celular , Simulação por Computador , DNA/metabolismo , Dano ao DNA , Reparo do DNA/genética , Enzimas Reparadoras do DNA/genética , Proteínas de Ligação a DNA/genética , Humanos , Modelos Genéticos , Modelos Moleculares , Mutação , Conformação de Ácido Nucleico , Saccharomyces cerevisiae/genética
16.
Gynecol Oncol ; 157(1): 245-251, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31980219

RESUMO

OBJECTIVES: To apply the Proactive Molecular Risk Classifier for Endometrial Cancer (ProMisE) to a consecutive series of endometrial cancer (EC) patients diagnosed at a tertiary referral center and assign EC specimens to one of four molecular subgroups using immunohistochemistry (IHC) for p53/mismatch repair protein expression and sequencing for Polymerase Epsilon Exonuclease Domain Mutations (POLE-EDM). Mismatch Repair Deficient (MMR-D) cases were more thoroughly investigated to identify underlying somatic or germline genetic defects. METHODS: Hundred-and eight consecutive endometrial cancer patients, diagnosed between March 2017 and April 2019, were subjected to immunohistochemical and molecular analysis, according to ProMisE. IHC for p53 and the mismatch repair proteins (MLH1, PMS2, MSH6 and PMS2) was performed. All patients were also tested for POLE-EDM by Sanger sequencing. In addition, tumor and corresponding normal tissue of cases with abnormal MMR IHC were tested by PCR for microsatellite instability (MSI) (MSI analysis system, Promega). Hypermethylation of MLH1 promotor was tested with (methylation specific) multiplex ligation dependent probe amplification. MMR-D cases were subjected to germline mutation analysis of the mismatch repair genes, using next generation sequencing on MiSeq (Illumina) with the BRCA Hereditary Cancer MASTR Plus, (Multiplicom/Agilent), RNA mutation analysis and MLPA. RESULTS: FIGO classification was stage IA (n = 54), IB (n = 22) II(n = 8), III(n = 18) and IV(n = 6). Of the 33 patients with MMR-D on IHC (31%), 26 showed MLH1 promotor hypermethylation as the probable cause of MMR-D. The remaining 7 patients without MLH1 promotor hypermethylation were referred for germline analysis of Lynch syndrome. Six patients carried a pathogenic germline mutation in one of the mismatch repair genes: MSH6(n = 3), PMS2(n = 1), MLH1(n = 1) and MSH2 (n = 1). Pathogenic POLE-EDM were identified in 7 (6%) patients. Multiple molecular features (POLE-EDM + MMR-D or POLE-EDM + p53 abnormal) were observed in 4 patients (4%). A high concordance between MMR-D and microsatellite instability was observed in our cohort. In cases of a genetic defect in the MMR genes, we do note a large proportion of cases exhibiting microsatellite instability. On the contrary a hypermutation state, as seen in POLE EDM, does not result in accompanied phenotypic changes in MSI status. CONCLUSION: The ProMisE classification proved to be an efficient and easily implementable system. Future research should elucidate the precise biological and prognostic meaning of the cases with multiple molecular markers.


Assuntos
Reparo de Erro de Pareamento de DNA , Enzimas Reparadoras do DNA/genética , Neoplasias do Endométrio/classificação , Idoso , Idoso de 80 Anos ou mais , DNA Polimerase II/genética , DNA Polimerase II/metabolismo , Enzimas Reparadoras do DNA/deficiência , Enzimas Reparadoras do DNA/metabolismo , Neoplasias do Endométrio/genética , Neoplasias do Endométrio/metabolismo , Neoplasias do Endométrio/patologia , Feminino , Humanos , Imuno-Histoquímica , Instabilidade de Microssatélites , Pessoa de Meia-Idade , Proteína 1 Homóloga a MutL/deficiência , Proteína 1 Homóloga a MutL/genética , Proteína 1 Homóloga a MutL/metabolismo , Estadiamento de Neoplasias , Proteínas de Ligação a Poli-ADP-Ribose/genética , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , Proteína Supressora de Tumor p53/genética
18.
Nucleic Acids Res ; 48(1): 231-248, 2020 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-31722399

RESUMO

Cockayne Syndrome (CS) is a severe neurodegenerative and premature aging autosomal-recessive disease, caused by inherited defects in the CSA and CSB genes, leading to defects in transcription-coupled nucleotide excision repair (TC-NER) and consequently hypersensitivity to ultraviolet (UV) irradiation. TC-NER is initiated by lesion-stalled RNA polymerase II, which stabilizes the interaction with the SNF2/SWI2 ATPase CSB to facilitate recruitment of the CSA E3 Cullin ubiquitin ligase complex. However, the precise biochemical connections between CSA and CSB are unknown. The small ubiquitin-like modifier SUMO is important in the DNA damage response. We found that CSB, among an extensive set of other target proteins, is the most dynamically SUMOylated substrate in response to UV irradiation. Inhibiting SUMOylation reduced the accumulation of CSB at local sites of UV irradiation and reduced recovery of RNA synthesis. Interestingly, CSA is required for the efficient clearance of SUMOylated CSB. However, subsequent proteomic analysis of CSA-dependent ubiquitinated substrates revealed that CSA does not ubiquitinate CSB in a UV-dependent manner. Surprisingly, we found that CSA is required for the ubiquitination of the largest subunit of RNA polymerase II, RPB1. Combined, our results indicate that the CSA, CSB, RNA polymerase II triad is coordinated by ubiquitin and SUMO in response to UV irradiation. Furthermore, our work provides a resource of SUMO targets regulated in response to UV or ionizing radiation.


Assuntos
DNA Helicases/genética , Enzimas Reparadoras do DNA/genética , Reparo do DNA , Proteínas de Ligação a Poli-ADP-Ribose/genética , Processamento de Proteína Pós-Traducional , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/genética , Fatores de Transcrição/genética , Transcrição Genética , Ubiquitina/genética , Linhagem Celular Transformada , Linhagem Celular Tumoral , DNA Helicases/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Células Epiteliais/efeitos da radiação , Fibroblastos/citologia , Fibroblastos/metabolismo , Fibroblastos/efeitos da radiação , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Humanos , Osteoblastos/citologia , Osteoblastos/metabolismo , Osteoblastos/efeitos da radiação , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Sumoilação , Fatores de Transcrição/metabolismo , Ubiquitina/metabolismo , Ubiquitinação , Raios Ultravioleta
19.
Mol Cell ; 77(5): 1080-1091.e8, 2020 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-31862156

RESUMO

Enzymatic processing of DNA underlies all DNA repair, yet inappropriate DNA processing must be avoided. In vertebrates, double-strand breaks are repaired predominantly by non-homologous end joining (NHEJ), which directly ligates DNA ends. NHEJ has the potential to be highly mutagenic because it uses DNA polymerases, nucleases, and other enzymes that modify incompatible DNA ends to allow their ligation. Using frog egg extracts that recapitulate NHEJ, we show that end processing requires the formation of a "short-range synaptic complex" in which DNA ends are closely aligned in a ligation-competent state. Furthermore, single-molecule imaging directly demonstrates that processing occurs within the short-range complex. This confinement of end processing to a ligation-competent complex ensures that DNA ends undergo ligation as soon as they become compatible, thereby minimizing mutagenesis. Our results illustrate how the coordination of enzymatic catalysis with higher-order structural organization of substrate maximizes the fidelity of DNA repair.


Assuntos
Quebras de DNA de Cadeia Dupla , Reparo do DNA por Junção de Extremidades , Instabilidade Genômica , Animais , DNA Ligases/genética , DNA Ligases/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Proteína Quinase Ativada por DNA/genética , Proteína Quinase Ativada por DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Autoantígeno Ku/genética , Autoantígeno Ku/metabolismo , Modelos Genéticos , Complexos Multiproteicos , Diester Fosfórico Hidrolases/genética , Diester Fosfórico Hidrolases/metabolismo , Imagem Individual de Molécula , Fatores de Tempo , Proteínas de Xenopus/genética , Proteínas de Xenopus/metabolismo , Xenopus laevis
20.
Anticancer Res ; 39(12): 6731-6741, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31810938

RESUMO

BACKGROUND/AIM: Histone deacetylase 6 (HDAC6) is considered as one of the most promising targets in drug development for cancer therapy. Drug resistance is a major cause of treatment failure in many cancers including glioblastoma (GBM), the most lethal malignant tumor. The role of HDAC6 in GBM resistance and its underlying mechanisms have not been well elucidated. Herein, we investigated the function of HDAC6 in modulating GBM resistance. MATERIALS AND METHODS: The anticancer effects of four structurally distinct selective HDAC6 inhibitors were addressed using western blot, flow cytometry, CCK-8 assay, and CI in temozolomide (TMZ)-resistant GBM cells. RESULTS: We showed that HDAC6-selecitve inhibitors block activation of the EGFR and p53 pathways in TMZ-resistant GBM cells. Importantly, the inhibition of HDAC6 correlates with increased levels of MSH2 and MSH6, key DNA mismatch repair proteins, in TMZ-resistant GBM cells. In addition to the MSH, HDAC6 inhibitors decrease MGMT expression in TMZ-resistant GBM cells. Furthermore, HDAC6 inhibitors increase TMZ sensitivity and efficiently induce apoptosis in TMZ-resistant GBM cells. CONCLUSION: Selective inhibition of HDAC6 may be a promising strategy for the treatment of TMZ-resistant GBM.


Assuntos
Neoplasias Encefálicas/enzimologia , Proteínas de Ligação a DNA/metabolismo , Resistencia a Medicamentos Antineoplásicos , Glioblastoma/enzimologia , Desacetilase 6 de Histona/antagonistas & inibidores , Proteína 2 Homóloga a MutS/metabolismo , Antineoplásicos Alquilantes/uso terapêutico , Derivados de Benzeno/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Linhagem Celular Tumoral , Sobrevivência Celular , Reparo de Erro de Pareamento de DNA/fisiologia , Metilases de Modificação do DNA/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Receptores ErbB/metabolismo , Glioblastoma/tratamento farmacológico , Desacetilase 6 de Histona/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Humanos , Ácidos Hidroxâmicos/farmacologia , Indóis/farmacologia , Pirimidinas/farmacologia , Temozolomida/uso terapêutico , Proteína Supressora de Tumor p53/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Regulação para Cima
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