DOUBLE BREAKING OF DNA THREADS AND GASTRIC CANCER

Relevance: Gastric cancer all over the world is ranked 4th in morbidity and 2nd in mortality [1], which is one of the most important social problems of society. GC is a complex disease that causes factors of environmental and host factors, causing factors that contribute to high mortality of gastric cancer, including its silent course, late clinical manifestations and underlying biological and genetic heterogeneity. Given the tacit and aggressive nature of gastric cancer, patients seek medical help in advanced stages. Modern science, having the opportunity to study methods for the study of oncological pathology, requires the search for diagnostic methods and the introduction of new personalized methods and monitoring in the treatment of oncological diseases. Phosphorylation of histone H2AX on Serine IY residues with the endpoint Carboxyl (which produces yH2AX) is a sensitive marker for DNA double-strand break (DSB) repair. Double-strand DNA breaks cause severe damage that can cause genomic instability, resulting in cancer [2,3] [4] Diseases of a person with defects in these processes often exhibit a predisposition to cancer [5]. A key component in DNA repair is the histone H2AX protein, which rapidly becomes phosphorylated at Serine IY residues from the carboxyl endpoint (Carboxyl endpoint) (Serina c-IY) in order to form yH2AX at the appropriate sites of the DB. Within 30 minutes after DB formation, a large number of yH2AX molecules form in chromatin around the site of decomposition, forming a focus where proteins involved in DNA repair and accumulation of chromatin remodeling are accumulated [6] This Amplification enables to detect individual DB with an anti-yH2AX antibody.

Download Full-text

Histone H2A Phosphorylation Controls Crb2 Recruitment at DNA Breaks, Maintains Checkpoint Arrest, and Influences DNA Repair in Fission Yeast

Molecular and Cellular Biology ◽

10.1128/mcb.24.14.6215-6230.2004 ◽

2004 ◽

Vol 24 (14) ◽

pp. 6215-6230 ◽

Cited By ~ 144

Author(s):

Toru M. Nakamura ◽

Li-Lin Du ◽

Christophe Redon ◽

Paul Russell

Keyword(s):

Dna Repair ◽

Fission Yeast ◽

Large Scale ◽

Dna Helicase ◽

Histone H2a ◽

Dna Breaks ◽

Histone H2ax ◽

Wide Range ◽

Carboxy Terminal ◽

Damaged Dna

ABSTRACT Mammalian ATR and ATM checkpoint kinases modulate chromatin structures near DNA breaks by phosphorylating a serine residue in the carboxy-terminal tail SQE motif of histone H2AX. Histone H2A is similarly regulated in Saccharomyces cerevisiae. The phosphorylated forms of H2AX and H2A, known as γ-H2AX and γ-H2A, are thought to be important for DNA repair, although their evolutionarily conserved roles are unknown. Here, we investigate γ-H2A in the fission yeast Schizosaccharomyces pombe. We show that formation of γ-H2A redundantly requires the ATR/ATM-related kinases Rad3 and Tel1. Mutation of the SQE motif to AQE (H2A-AQE) in the two histone H2A genes caused sensitivity to a wide range of genotoxic agents, increased spontaneous DNA damage, and impaired checkpoint maintenance. The H2A-AQE mutations displayed a striking synergistic interaction with rad22Δ (Rad52 homolog) in ionizing radiation (IR) survival. These phenotypes correlated with defective phosphorylation of the checkpoint proteins Crb2 and Chk1 and a failure to recruit large amounts of Crb2 to damaged DNA. Surprisingly, the H2A-AQE mutations substantially suppressed the IR hypersensitivity of crb2Δ cells by a mechanism that required the RecQ-like DNA helicase Rqh1. We propose that γ-H2A modulates checkpoint and DNA repair through large-scale recruitment of Crb2 to damaged DNA. This function correlates with evidence that γ-H2AX regulates recruitment of several BRCA1 carboxyl terminus domain-containing proteins (NBS1, 53BP1, MDC1/NFBD1, and BRCA1) in mammals.

Download Full-text

The Clinicopathological Features and Genetic Mutations in Gastric Cancer Patients According to EMAST and MSI Status

Cancers ◽

10.3390/cancers12030551 ◽

2020 ◽

Vol 12 (3) ◽

pp. 551

Author(s):

Wen-Liang Fang ◽

Ming-Huang Chen ◽

Kuo-Hung Huang ◽

Shih-Ching Chang ◽

Chien-Hsing Lin ◽

...

Keyword(s):

Gastric Cancer ◽

Dna Repair ◽

Survival Rate ◽

Cancer Patients ◽

Clinicopathological Features ◽

Akt Pathway ◽

Genetic Mutations ◽

Tetranucleotide Repeats ◽

Gastric Cancer Patients ◽

T Category

Background: There has been no report regarding the clinicopathological features and genetic mutations regarding elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) in gastric cancer (GC). Methods: The correlation among EMAST status, microsatellite instability (MSI) status, mutations of common GC-related genes and 16 DNA repair-associated genes, and the clinicopathological features were analyzed. Results: Among the 360 GC patients enrolled, there were 76 (21.1%) with EMAST+ tumors and 284 with EMAST− tumors, and 59 (16.4%) were MSI-high (MSI-H) tumors, and 301 were microsatellite stable (MSS) tumors. Patients with EMAST+ tumors exhibited an earlier pathological T category and had more genetic mutations in the PI3K/AKT pathway, ARID1A and DNA repair-associated genes than those with EMAST− tumors. Patients with MSI-H tumors have more genetic mutations in the PI3K/AKT pathway and DNA repair-associated genes than those with MSS tumors. In the subgroup analysis for MSI-H GC, EMAST+ tumors were associated with earlier pathological T and N categories, earlier TNM stages, higher frequency of DNA-repair-associated genetic mutations, and a better survival rate than EMAST− tumors. Conclusions: PI3K/AKT pathway mutations may play an important role in EMAST+ and/or MSI-H GC. EMAST+/MSI-H tumors seem to represent a different subtype of gastric cancer from EMAST−/MSI-H tumors.

Download Full-text

Mechanistic insight into the role of Poly(ADP-ribosyl)ation in DNA topology modulation and response to DNA damage

Mutagenesis ◽

10.1093/mutage/gez045 ◽

2019 ◽

Vol 35 (1) ◽

pp. 107-118

Author(s):

Bakhyt T Matkarimov ◽

Dmitry O Zharkov ◽

Murat K Saparbaev

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Genotoxic Stress ◽

Strand Break ◽

Dna Supercoiling ◽

Dna Strand Breaks ◽

Chromosomal Dna ◽

Dna Breaks ◽

Strand Breaks ◽

Dna Strand

Abstract Genotoxic stress generates single- and double-strand DNA breaks either through direct damage by reactive oxygen species or as intermediates of DNA repair. Failure to detect and repair DNA strand breaks leads to deleterious consequences such as chromosomal aberrations, genomic instability and cell death. DNA strand breaks disrupt the superhelical state of cellular DNA, which further disturbs the chromatin architecture and gene activity regulation. Proteins from the poly(ADP-ribose) polymerase (PARP) family, such as PARP1 and PARP2, use NAD+ as a substrate to catalyse the synthesis of polymeric chains consisting of ADP-ribose units covalently attached to an acceptor molecule. PARP1 and PARP2 are regarded as DNA damage sensors that, upon activation by strand breaks, poly(ADP-ribosyl)ate themselves and nuclear acceptor proteins. Noteworthy, the regularly branched structure of poly(ADP-ribose) polymer suggests that the mechanism of its synthesis may involve circular movement of PARP1 around the DNA helix, with a branching point in PAR corresponding to one complete 360° turn. We propose that PARP1 stays bound to a DNA strand break end, but rotates around the helix displaced by the growing poly(ADP-ribose) chain, and that this rotation could introduce positive supercoils into damaged chromosomal DNA. This topology modulation would enable nucleosome displacement and chromatin decondensation around the lesion site, facilitating the access of DNA repair proteins or transcription factors. PARP1-mediated DNA supercoiling can be transmitted over long distances, resulting in changes in the high-order chromatin structures. The available structures of PARP1 are consistent with the strand break-induced PAR synthesis as a driving force for PARP1 rotation around the DNA axis.

Download Full-text

Ataxia Telangiectasia

Blood ◽

10.1182/blood.v118.21.sci-7.sci-7 ◽

2011 ◽

Vol 118 (21) ◽

pp. SCI-7-SCI-7

Author(s):

Richard A. Gatti

Keyword(s):

Dna Repair ◽

Ataxia Telangiectasia ◽

Conflicts Of Interest ◽

Severe Combined Immunodeficiency ◽

Strand Break ◽

Diagnostic Methods ◽

Neurological Dysfunction ◽

Single Strand Break ◽

Atm Kinase ◽

Clinical Radiosensitivity

Abstract Abstract SCI-7 Ataxia-telangiectasia (A-T) is the prototype for an expanded group of inherited radiation sensitive disorders that together define the XCIND syndrome: x-ray hypersensitivity, cancer, immunodeficiency, neurological dysfunction, and DNA repair deficiency. Although the clinical radiosensitivity of these disorders can be tested in the clinical laboratory, diagnostic methods remain limited and in need of further validation. Without exception, to date, sensitivity to ionizing radiation appears to be integrally associated with double strand break (DSB) repair defects and lymphoid cancer susceptibility, setting these disorders apart from single strand break repair disorders such as xeroderma pigmentosum. Responding within seconds to DSB damage are ATM kinase, the protein lacking in A-T, and the NMR complex (nibrin, Mre11, and Rad50). The latter three proteins are associated with three additional XCIND disorders (nibrin deficiency [aka nijmegen breakage syndrome], Mre11 deficiency [ATLD], and Rad50 deficiency). ATM kinase activates a myriad of other proteins that 1) halt DNA synthesis, replication, and the progression of the cell cycle; 2) form a complex protein “mesh” to physically stabilize the broken DNA strands; and 3) restore the integrity of the breaks before they unravel to create even larger chromosomal lesions and resulting malignancies. Another ATM-dependent cancer link involves the downregulation of ATM by microRNA-421. MicroRNA-421 is upregulated by the transcription factor N-myc. Despite this, neuroblastomas are not commonly observed in A-T or XCIND patients. Another subset of XCIND-associated disorders lacks proteins the drive the nonhomologous end joining pathway of DNA repair. Several of these diseases present in infancy as B−/T− severe combined immunodeficiency, or SCID, and are frequent candidates for stem cell transplantation. Attempts to ablate existing bone marrow prior to transplantation may further compromise such patients if they are inherently radiosensitive. Thus, attempts to preselect such patients and reduce radiation dosages may improve general post-transplantation survival. While most protein deficiencies can be diagnosed by immunoblots of appropriate cellular fractions, nonfunctional proteins are not detected by this platform. Colony survival assays (CSA) measure the ability of replicating cells (e.g., lymphoblasts or fibroblasts) to survive after exposure to radiation. Although causal proof that CSA can predict clinical radiosensitivity is lacking, the reduced percent survival fraction (i.e., radiosensitivity) of A-T, N-Bromosuccinimide, or Fanconi cell lines can be abrogated by introducing the mutated cognate gene. Other surrogate assays for radiosensitivity include kinetic studies, pre-irradiation and post-irradiation of γ-H2AX or SMC1 phosphorylation. Ultimately, DNA sequencing of a candidate gene can pinpoint the underlying pathogenesis of radiosensitivity in an XCIND disorder. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

ERCC1 mRNA expression and XRCC1 polymorphism as predictive factors for overall survival in gastric cancer patients receiving platinum based chemotherapy

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.2512 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 2512-2512 ◽

Cited By ~ 2

Author(s):

J. Wei ◽

B. Liu ◽

Z. Zou ◽

X. Qian ◽

W. Zhang ◽

...

Keyword(s):

Gastric Cancer ◽

Overall Survival ◽

Dna Repair ◽

Survival Time ◽

Cancer Patients ◽

Predictive Factors ◽

Median Survival Time ◽

Platinum Based Chemotherapy ◽

Ercc1 Expression ◽

Gastric Cancer Patients

2512 Background: DNA repair was considered to play the key role in the platinum chemotherapy. ERCC1, XPD and XRCC1, three major components of the DNA repair pathway, are critical to outcome for patients treated with platinum based chemotherapy. Methods: Overall survival times in 48 stage III (47.9%) and IV (52.1%) gastric cancer patients were investigated. mRNA was isolated from formalin- fixed paraffin-embeded pretreatment primary tumor specimens and the relative expression of ERCC1 to the internal reference geneβ-actin was measured using real-time quantitative reverse transcriptase polymerase chain reaction. Two single nucleotide polymorphisms (SNPs) (XPD Lys751Gln and XRCC1 Arg399Gln) were also investigated using 5’ nuclease allelic discrimination assay (TaqMan). Results: Median age was 55 years (range: 23 to 75 years); 35 males and 13 females; median survival time was 397 days. The median ERCC1 gene expression level from all 48 gastric tumors was 1.16, and the cutoff values for chemotherapy was 0.30. The median survival time for patients with lower ERCC1 expression (31 of 48 patients) was 496 days, compared with 218 days for patients with higher ERCC1 expression (P < 0.0001). SNP of XRCC1 Arg399Gln was measured in 47 gastric cancer patients (97.92%). Median overall survival time was longer in patients with favorite allele G in codon 399 of XRCC1 (40 of 47 patients) than in others (respectively 420 days vs 218 days, P = 0.017). No significant relationship was found between SNP of XPD Lys751Gln and outcome of gastric cancer patients. Conclusions: These findings suggested that intratumoral ERCC1 mRNA expression and polymorphism of XRCC1 might be prominent predictive factors for overall survival of gastric cancer patients treated with platinum based chemotherapy. Multi-center clinical trial has been suggested. No significant financial relationships to disclose.

Download Full-text

Association of DNA Repair and Drug Transporter in Relation to Chemosensitivity in Primary Culture of Thai Gastric Cancer Patients

Biological and Pharmaceutical Bulletin ◽

10.1248/bpb.b17-00688 ◽

2018 ◽

Vol 41 (3) ◽

pp. 360-367 ◽

Cited By ~ 2

Author(s):

Pattama Wongsirisin ◽

Sirikan Limpakan Yamada ◽

Supachai Yodkeeree ◽

Wanisa Punfa ◽

Pornngarm Limtrakul

Keyword(s):

Gastric Cancer ◽

Dna Repair ◽

Primary Culture ◽

Cancer Patients ◽

Drug Transporter ◽

Gastric Cancer Patients

Download Full-text

Examination of RAD51 gene G135C polymorphism in gastric cancer patients in northeastern Anatolia

Archives of Biological Sciences ◽

10.2298/abs181121002g ◽

2019 ◽

Vol 71 (2) ◽

pp. 209-213

Author(s):

Ilhami Gok ◽

Ozkan Ozden

Keyword(s):

Gastric Cancer ◽

Dna Repair ◽

Cancer Patients ◽

Repair Gene ◽

Repair Capacity ◽

Dna Repair Capacity ◽

Rad51 Gene ◽

Genotype Frequencies ◽

Increased Risk ◽

Gastric Cancer Patients

Polymorphisms of DNA repair and genome integrity genes are associated with DNA repair capacity and elevated cancer risk. To establish an association between the pattern of polymorphism and the incidence of any type of cancer, studies across different populations are required. Polymorphic regions have been identified in the RAD51 repair gene in various cancer types; however, the influence of specific genetic variants on gastric cancer prevalence has not been empirically demonstrated. We conducted a case-control study with 76 gastric cancer patients and 78 healthy individuals from northeastern Anatolia to examine the association between polymorphism and gastric cancer. We genotyped the previously identified G135C polymorphism of RAD51 in all individuals and estimated the allele and genotype frequencies in the two groups. Our results indicated that the two groups differed both in allele and genotype frequencies. Additionally, a significant and elevated odd ratio (3.53) of gastric cancer for the C allele of RAD51 was observed. The genotypes GC and CC had also significant and high odd ratios (>3.75). Our results indicate that G135C polymorphism of the RAD51 gene was associated with an increased risk of gastric cancer in the examined population.

Download Full-text

ADAR-mediated RNA editing of DNA:RNA hybrids is required for DNA double strand break repair

Nature Communications ◽

10.1038/s41467-021-25790-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Sonia Jimeno ◽

Rosario Prados-Carvajal ◽

María Jesús Fernández-Ávila ◽

Sonia Silva ◽

Domenico Alessandro Silvestris ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Rna Editing ◽

Genomic Stability ◽

Strand Break ◽

Dna Lesions ◽

Dna Breaks ◽

Dna Double Strand Break ◽

Editing Enzyme

AbstractThe maintenance of genomic stability requires the coordination of multiple cellular tasks upon the appearance of DNA lesions. RNA editing, the post-transcriptional sequence alteration of RNA, has a profound effect on cell homeostasis, but its implication in the response to DNA damage was not previously explored. Here we show that, in response to DNA breaks, an overall change of the Adenosine-to-Inosine RNA editing is observed, a phenomenon we call the RNA Editing DAmage Response (REDAR). REDAR relies on the checkpoint kinase ATR and the recombination factor CtIP. Moreover, depletion of the RNA editing enzyme ADAR2 renders cells hypersensitive to genotoxic agents, increases genomic instability and hampers homologous recombination by impairing DNA resection. Such a role of ADAR2 in DNA repair goes beyond the recoding of specific transcripts, but depends on ADAR2 editing DNA:RNA hybrids to ease their dissolution.

Download Full-text