Role Of DNA Repair Genes Research Articles

Polymorphisms of DNA Repair Genes in Thyroid Cancer.

The incidence of thyroid cancer, one of the most common forms of endocrine cancer, is increasing rapidly worldwide in developed and developing countries. Various risk factors can increase susceptibility to thyroid cancer, but particular emphasis is put on the role of DNA repair genes, which have a significant impact on genome stability. Polymorphisms of these genes can increase the risk of developing thyroid cancer by affecting their function. In this article, we present a concise review on the most common polymorphisms of selected DNA repair genes that may influence the risk of thyroid cancer. We point out significant differences in the frequency of these polymorphisms between various populations and their potential relationship with susceptibility to the disease. A more complete understanding of these differences may lead to the development of effective prevention strategies and targeted therapies for thyroid cancer. Simultaneously, there is a need for further research on the role of polymorphisms of previously uninvestigated DNA repair genes in the context of thyroid cancer, which may contribute to filling the knowledge gaps on this subject.

Precise CRISPR/Cpf1 genome editing system in the Deinococcus radiodurans with superior DNA repair mechanisms

Deinococcus radiodurans, with its high homologous recombination (HR) efficiency of double-stranded DNA breaks (DSBs), is a model organism for studying genome stability maintenance and an attractive microbe for industrial applications. Here, we developed an efficient CRISPR/Cpf1 genome editing system in D. radiodurans by evaluating and optimizing double-plasmid strategies and four Cas effector proteins from various organisms, which can precisely introduce different types of template-dependent mutagenesis without off-target toxicity. Furthermore, the role of DNA repair genes in determining editing efficiency in D. radiodurans was evaluated by introducing the CRISPR/Cpf1 system into 13 mutant strains lacking various DNA damage response and repair factors. In addition to the crucial role of RecA-dependent HR required for CRISPR/Cpf1 editing, D. radiodurans showed higher editing efficiency when lacking DdrB, the single-stranded DNA annealing (SSA) protein involved in the RecA-independent DSB repair pathway. This suggests a possible competition between HR and SSA pathways in the CRISPR editing of D. radiodurans. Moreover, off-target effects were observed during the genome editing of the pprI knockout strain, a master DNA damage response gene in Deinococcus species, which suggested that precise regulation of DNA damage response is critical for a high-fidelity genome editing system.

DNA repair genes play a variety of roles in the development of fish embryos.

Embryogenesis is one of the most important life stages because it determines an organism's healthy growth. However, embryos of externally fertilizing species, such as most fish, are directly exposed to the environment during development and may be threatened by DNA damaging factors (pollutants, UV, reactive oxygen species). To counteract the negative effects of DNA fragmentation, fish embryos evolved complex damage response pathways. DNA repair pathways have been extensively studied in some fish species, such as zebrafish (Danio rerio). Our literature review, on the other hand, revealed a paucity of knowledge about DNA damage response and repair in non-model aquaculture fish species. Further, several pieces of evidence underlie the additional role of DNA repair genes and proteins in organogenesis, spatiotemporal localization in different tissue, and its indispensability for normal embryo development. In this review, we will summarize features of different DNA repair pathways in course of fish embryo development. We describe how the expression of DNA repair genes and proteins is regulated during development, their organogenetic roles, and how the expression of DNA repair genes changes in response to genotoxic stress. This will aid in addressing the link between genotoxic stress and embryo phenotype. Furthermore, available data indicate that embryos can repair damaged DNA, but the effects of early-life stress may manifest later in life as behavioral changes, neoplasia, or neurodegeneration. Overall, we conclude that more research on DNA repair in fish embryos is needed.

Genetic heterogeneity and enrichment of variants in DNA-repair genes in ameloblastoma.

Ameloblastomas are a group of relativelycommon odontogenic tumors that frequentlyoriginate from the dental epithelium. These tumors are aggressive in nature and present as slow-growing painless cortical expansion of the jaw. Histologically, the follicular and plexiform subtypes constitute two-thirds of solid/multicystic ameloblastomas. The objective of this study was to understand the genetic architecture of follicular and plexiform ameloblastomas using deep whole-exome sequencing. Archived formalin-fixed paraffin-embedded tissue blocks of follicular (n= 4) and plexiform (n= 6) ameloblastomas were retrieved and genomic DNAs were isolated from the tumor tissue dissected from the formalin-fixed paraffin-embedded block. The exomes were enriched using the Integrated DNA TechnologiesExome Research Panel (IDT, Coralville, IA) and paired-end sequencing was completed on an Illumina NovaSeq 6000 with an average output of 20 GB of data resulting in a mean coverage of 400×. Variant analysis was completed using custom-developed software: Rapid Understanding of Nucleotide variant Effect Software and variant integration and knowledge interpretation in genomes. Our analyses focused on examining somatic variants (gnomAD minor allele frequency ≤1%) in genes found on an FoodandDrugAdministration-approved clinical cancer sequencing panel (FoundationOne®CDx). In follicular tumors, variants (>20% of the reads) were identified in BRAF, KMT2D, and ABL1 genes. In plexiform tumors, variants (>20% of the reads) were identified in ALK, BRAF, KRAS, KMT2D, SMO, KMT2A, and BRCA2 genes. Enrichment analysis showed a significant role of DNA repair genes in the development of these tumors. The variants identified in follicular and plexiform ameloblastomas were enriched in DNA-repair genes. The observed genetic heterogeneity in these ameloblastomas may contribute to the aggressive nature and recurrence risk of these tumors.

Polyglutamine diseases.

Polyglutamine diseases are a collection of nine CAG trinucleotide expansion disorders, presenting with a spectrum of neurological and clinical phenotypes. Recent human, mouse and cell studies of Huntington's diseasehave highlighted the role of DNA repair genes in somatic expansion of the CAG repeat region, modifying disease pathogenesis. Incomplete splicing of the HTT gene has also been shown to occur in humans, with the resulting exon 1 fragment most probably contributing to the Huntington's disease phenotype. In the spinocerebellar ataxias, studies have converged on transcriptional dysregulation of ion channels as a key disease modifier. In addition, advances have been made in understanding how increased levels of toxic, polyglutamine-expanded proteins can arise in the spinocerebellar ataxias through post-transcriptional and -translational modifications and autophagic mechanisms. Recent studies in spinal and bulbar muscular atrophyimplicate similar pathogenic pathways to the more common polyglutamine diseases, highlighting autophagy stimulation as a potential therapeutic target. Finally, the therapeutic use of antisense oligonucleotides in several polyglutamine diseases has shown preclinical benefits and serves as potential future therapies in humans.

The association of oxidative stress and DNA damage with XRCC1 and XRCC3 polymorphisms in radiology technicians.

Ionizing radiation has widespread use in medicine in the diagnosis and treatment of many medical conditions. Radiology technicians are one group that is occupationally exposed to low doses of radiation. There are questions regarding whether low dose exposure to radiation could have long-term health consequences. Assessing the effect of radiation on genetic material is essential for appraising long-term health results. Hereditary variations in DNA repair genes cause differentiation in individual responses to radiation related health effects. This study aimed to determine oxidative stress and DNA damage, and their relationship to XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) polymorphisms in radiology technicians occupationally exposed to low dose radiation. Peripheral blood samples were collected from 45 radiology technicians and age-matched with 40 healthy control individuals working in office environments. Our results showed that radiology technicians had significantly greater oxidative stress and DNA damage than the control group, and women appeared more susceptible to occupational radiation exposure than men. Individuals with wild-type genotypes for XRCC1 (Arg/Arg) and XRCC3 (Thr/Thr) had less DNA damage. Lower DNA damage levels could be explained by the enhanced capacity to repair low dose radiation induced DNA damage. Further studies are needed to evaluate the role of DNA repair genes in individuals that are occupationally exposed to low dose radiation.

Large-scale generation and phenotypic characterization of zebrafish CRISPR mutants of DNA repair genes

A systematic knowledge of the roles of DNA repair genes at the level of the organism has been limited due to the lack of appropriate experimental approaches using animal model systems. Zebrafish has become a powerful vertebrate genetic model system with availability due to the ease of genome editing and large-scale phenotype screening. Here, we generated zebrafish mutants for 32 DNA repair and replication genes through multiplexed CRISPR/Cas9-mediated mutagenesis. Large-scale phenotypic characterization of our mutant collection revealed that three genes (atad5a, ddb1, pcna) are essential for proper embryonic development and hematopoiesis; seven genes (apex1, atrip, ino80, mre11a, shfm1, telo2, wrn) are required for growth and development during juvenile stage and six genes (blm, brca2, fanci, rad51, rad54l, rtel1) play critical roles in sex development. Furthermore, mutation in six genes (atad5a, brca2, polk, rad51, shfm1, xrcc1) displayed hypersensitivity to DNA damage agents. Our zebrafish mutant collection provides a unique resource for understanding of the roles of DNA repair genes at the organismal level.

Abstract 2072: DNA repair pathway score is associated with cancer aggressiveness and worse survival in hepatocellular carcinoma (HCC)

Abstract Background: Hepatocellular carcinoma (HCC) is one of the most common malignancies and a leading cause of cancer-related deaths worldwide. A prognostic biomarker based on cancer biology can tailor treatments according to patient prognosis. DNA repair mechanisms activated following DNA damage are essential to suppress carcinogenesis. Hence, deficiencies in DNA damage repair pathways promote carcinogenesis. The role of DNA repair genes in HCC is actively being investigated, but contradictory reports on some DNA repair-related genes have complicated our overall understanding of DNA repair in HCC progression. Though it is important to study the function of each individual DNA repair-related gene, it is more important to understand the role of the entire DNA repair pathway in HCC progression. We hypothesize that the enhancement of the DNA repair pathway is associated with worse survival in HCC patients. Method: A total of 749 HCC patients from 5 cohorts (TCGA, GSE6764, GSE89377, GSE56545, GSE76427) were studied to examine the relationships between enhancement of DNA repair and cancer aggressiveness, tumor immune microenvironment, and patient survival in HCC utilizing a DNA repair pathway score, which was calculated by Gene Set Variation Analysis (GSVA) with Hallmark DNA repair gene set. Results: We found that DNA repair pathway was enhanced by stepwise carcinogenic process of HCC and significantly enhanced in higher grade HCC compared with low grade tumor in two cohorts (both p < 0.001). DNA repair high HCC was associated with worse survival (disease-free survival: p < 0.001, disease-specific survival: p = 0.002, and overall survival: p < 0.001), elevated intratumor heterogeneity (p = 0.036) and mutation load (p < 0.001), but not with fraction of immune cell infiltration nor immune response in the TCGA cohort. HCC tumors with DNA repair high score enriched proliferation-related (E2F targets, G2M checkpoint, mitotic spindle, MYC target v1 and v2) and other cancer aggressiveness-related (unfolded protein response, PI3K/AKT/MTOR signaling, MTORC1, notch signaling, and WNT-β catenin signaling) gene sets. Interestingly, these features were more pronounced in early HCC compared to advanced HCC. DNA repair high HCC was associated with elevated mutation load, enriched proliferation- and other cancer aggressiveness-related gene sets and was associated with worse survival in early (grade 1 and grade 2) but not in advanced (grade 3) HCC. To our knowledge, this is the first study to use DNA repair pathway-related gene set expression data to examine and validate the clinical relevance of DNA repair pathway activity in HCC. Conclusion: The DNA repair score may be used to better understand and predict prognosis in HCC. Citation Format: Masanori Oshi, Tae Hee Kim, Yoshihisa Tokumaru, Li Yan, Ryusei Matsuyama, Itaru Endo, Leonid Cherkassky, Kazuaki Takabe. DNA repair pathway score is associated with cancer aggressiveness and worse survival in hepatocellular carcinoma (HCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2072.

Methylation Status of Arabidopsis DNA Repair Gene Promoters During Agrobacterium Infection Reveals Epigenetic Changes in Three Generations

Agrobacterium tumefaciens is a unique pathogen with the ability to transfer a portion of its DNA, the T-DNA, to other organisms. The role of DNA repair genes in Agrobacterium transformation remains controversial. In order to understand if the host DNA repair response and dynamics was specific to bacterial factors such as Vir proteins, T-DNA, and oncogenes, we profiled the expression and promoter methylation of various DNA repair genes. These genes belonged to nucleotide excision repair (NER), base excision repair (BER), mismatch repair (MMR), homologous recombination (HR), and non-homologous end joining (NHEJ) pathways. We infected Arabidopsis plants with different Agrobacterium strains that lacked one or more of the above components so that the influence of the respective factors could be analysed. Our results revealed that the expression and promoter methylation of most DNA repair genes was affected by Agrobacterium, and it was specific to Vir proteins, T-DNA, oncogenes, or the mere presence of bacteria. In order to determine if Agrobacterium induced any transgenerational epigenetic effect on the DNA repair gene promoters, we studied the promoter methylation in two subsequent generations of the infected plants. Promoters of at least three genes, CEN2, RAD51, and LIG4 exhibited transgenerational memory in response to different bacterial factors. We believe that this is the first report of Agrobacterium-induced transgenerational epigenetic memory of DNA repair genes in plants. In addition, we show that Agrobacterium induces short-lived DNA strand breaks in Arabidopsis cells, irrespective of the presence or absence of virulence genes and T-DNA.

Variants in Homologous Recombination Genes EXO1 and RAD51 Related with Premature Ovarian Insufficiency.

Premature ovarian insufficiency (POI) is characterized by cessation of menstruation before 40 years of age and elevated serum level of FSH (>25 IU/L). Recent studies have found a few causative genes responsible for POI enriched in meiotic recombination and DNA damage repair pathways. To investigate the role of variations in homologous recombination genes played in POI pathogenesis. The whole exome sequencing was performed in 50 POI patients with primary amenorrhea. Functional characterizations of the novel variants were carried out in budding yeast and human cell line. We identified 8 missense variants in 7 homologous recombination genes, including EXO1, RAD51, RMI1, MSH5, MSH2, MSH6, and MLH1. The mutation p.Thr52Ser in EXO1 impaired the meiotic process of budding yeast and p.Glu68Gly in RAD51-altered protein localization in human cells, both of them impaired the efficiency of homologous recombination repair for DNA double-stranded breaks in human cells. Our study first linked the variants of EXO1 and RAD51 with POI and further highlighted the role of DNA repair genes in ovarian dysgenesis.

Mutational diversity in mutY deficient Helicobacter pylori and its effect on adaptation to the gastric environment

Helicobacter pylori, a pathogenic bacterium that colonizes in the human stomach, harbors DNA repair genes to counter the gastric environment during chronic infection. In addition, H. pylori adapts to the host environment by undergoing antigenic phase variation caused by genomic mutations. The emergence of mutations in nucleotide sequences is one of the major factors underlying drug resistance and genetic diversity in bacteria. However, it is not clear how DNA repair genes contribute to driving the genetic change of H. pylori during chronic infection. To elucidate the physiological roles of DNA repair genes, we generated DNA repair-deficient strains of H. pylori (ΔuvrA, ΔuvrB, ΔruvA, Δnth, ΔmutY, ΔmutS, and Δung). We performed susceptibility testing to rifampicin in vitro and found that ΔmutY exhibited the highest mutation frequency among the mutants. The number of bacteria colonizing the stomach was significantly lower with ΔmutY strain compared with wild-type strains in a Mongolian gerbil model of H. pylori infection. Furthermore, we performed a genomic sequence analysis of the strains isolated from the Mongolian gerbil stomachs eight weeks after infection. We found that the isolated ΔmutY strains exhibited a high frequency of spontaneous G:C to T:A mutations. However, the frequency of phase variations in the ΔmutY strain was almost similar to the wild-type strain. These results suggest that MutY may play a role in modes of gastric environmental adaptation distinct from phase variation.

The role of DNA repair genes in radiation-induced adaptive response in Drosophila melanogaster is differential and conditional.

Studies in human and mammalian cell cultures have shown that induction of DNA repair mechanisms is required for the formation of stimulation effects of low doses of ionizing radiation, named "hormesis". Nevertheless, the role of cellular defense mechanisms in the formation of radiation-induced hormesis at the level of whole organism remains poorly studied. The aim of this work was to investigate the role of genes involved in different mechanisms and stages of DNA repair in radioadaptive response and radiation hormesis by lifespan parameters in Drosophila melanogaster. We studied genes that control DNA damage sensing (D-Gadd45, Hus1, mnk), nucleotide excision repair (mei-9, mus210, Mus209), base excision repair (Rrp1), DNA double-stranded break repair by homologous recombination (Brca2, spn-B, okr) and non-homologous end joining (Ku80, WRNexo), and the Mus309 gene that participates in several mechanisms of DNA repair. The obtained results demonstrate that in flies with mutations in studied genes radioadaptive response and radiation hormesis are absent or appear to a lesser extent than in wild-type Canton-S flies. Chronic exposure of γ-radiation in a low dose during pre-imaginal stages of development leads to an increase in expression of the studied DNA repair genes, which is maintained throughout the lifespan of flies. However, the activation of conditional ubiquitous overexpression of DNA repair genes does not induce resistance to an acute exposure to γ-radiation and reinforces its negative impact.

Differential Expression of DNA Repair Genes in Prognostically-Favorable versus Unfavorable Uveal Melanoma.

Expression of DNA repair genes was studied in uveal melanoma (UM) in order to identify genes that may play a role in metastases formation. We searched for genes that are differentially expressed between tumors with a favorable and unfavorable prognosis. Gene-expression profiling was performed on 64 primary UM from the Leiden University Medical Center (LUMC), Leiden, The Netherlands. The expression of 121 genes encoding proteins involved in DNA repair pathways was analyzed: a total of 44 genes differed between disomy 3 and monosomy 3 tumors. Results were validated in a cohort from Genoa and Paris and the The Cancer Genome Atlas (TCGA) cohort. Expression of the PRKDC, WDR48, XPC, and BAP1 genes was significantly associated with clinical outcome after validation. PRKDC was highly expressed in metastasizing UM (p < 0.001), whereas WDR48, XPC, and BAP1 were lowly expressed (p < 0.001, p = 0.006, p = 0.003, respectively). Low expression of WDR48 and XPC was related to a large tumor diameter (p = 0.01 and p = 0.004, respectively), and a mixed/epithelioid cell type (p = 0.007 and p = 0.03, respectively). We conclude that the expression of WDR48, XPC, and BAP1 is significantly lower in UM with an unfavorable prognosis, while these tumors have a significantly higher expression of PRKDC. Pharmacological inhibition of DNA-PKcs resulted in decreased survival of UM cells. PRKDC may be involved in proliferation, invasion and metastasis of UM cells. Unraveling the role of DNA repair genes may enhance our understanding of UM biology and result in the identification of new therapeutic targets.

Multi-omics analysis reveals the BRCA1 mutation and mismatch repair gene signatures associated with survival, protein expression, and copy number alterations in prostate cancer.

BackgroundRecent genomic analysis reveals that DNA repair gene mutations can be detected in 15–30% of patients in metastatic castration resistant prostate cancer depending on the population and clinical setting when comparing to a very small fraction in those with indolent localized diseases. The discovery and characterization of function associated with DNA repair gene mutations in prostate cancer patients may increase therapeutic options and lead to improved clinical outcomes.MethodsTo understand the role of DNA repair genes associated with other genomic alteration and signaling pathway, we applied an integrative analysis of multi-omics to The Cancer Genome Atlas (TCGA) prostate cancer dataset which contains 498 patients. We concurrently analyzed gene expression profiles, reverse phase protein lysate microarray (RPPA) data, and copy number alterations to examine the potential genomic mechanisms.ResultsWe identified the signature of “chromosome condensation”, “BRCA1 mutation”, and “mismatch repair” were associated with disease-free survival in prostate cancer. Through the concurrent analysis of gene expression profiles, reverse RPPA data, and copy number alterations, we found the three signatures are associated with cell cycle and DNA repair pathway and also most events of copy number gains.ConclusionsThis study presents a unique extension from DNA mutations to expressional functions, proteomic activities, and copy numbers of DNA repair genes in prostate cancer. Our findings revealed crucial prognostic markers and candidates for further biological and clinical investigations.

Lack of association between functional polymorphism of DNA repair genes (XRCC1, XPD) and clinical response in Indian chronic myeloid leukemia patients.

The resistance for the tyrosine kinase inhibitors in chronic myeloid leukemia (CML) occurs mainly due to BCR/ABL1 dependent and independent mechanisms. The defective DNA repair due to functional polymorphisms in DNA repair genes, might act as an etiological factor for leukemia progression. The study was carried out to understand the role of DNA repair genes (XRCC1, XPD) polymorphisms in Imatinib mesylate (IM) resistant CML patients. The study was carried out in total 87 CML patients (43 nonresponders-cases and 44 responders) who were treated with Imatinib. The treatment and follow-up was done according to European LeukemiaNet guidelines. The genotyping of selected SNPs were studied using RFLP and confirmed with Sanger sequencing (20%). The statistical analysis was performed using online tools (Socscistatistics and GraphPad InStat software). In our study no significant association was inferred between genotypes of DNA repair genes (XRCC1; rs1799782, rs25487, and XPD; rs13181) and complete cytogenetic response as well as molecular response. However there might be a possibility of association between XRCC1 Arg399Gln genotype AA/GA and cytogenetic response though it is statistically insignificant (p > 0.05). Though none of the genotypes of the DNA repair genes showed association with IM response, near association between XRCC1Arg399Gln genotype and cytogenetic response observed in our study. Hence, large sample size should be studied to establish the association of SNPs of DNA repair genes and IM response. Our study is a novel and important to explain the role of DNA repair genes polymorphisms in IM resistance.

Targeting DNA Repair Systems in Antitubercular Drug Development.

Infections with Mycobacterium tuberculosis, the causative agent of tuberculosis, are difficult to treat using currently available chemotherapeutics. Clinicians agree on the urgent need for novel drugs to treat tuberculosis. In this mini review, we summarize data that prompts the consideration of DNA repair-associated proteins as targets for the development of new antitubercular compounds. We discuss data, including gene expression data, that highlight the importance of DNA repair genes during the pathogenic cycle as well as after exposure to antimicrobials currently in use. Specifically, we report experiments on determining the essentiality of DNA repair-related genes. We report the availability of protein crystal structures and summarize discovered protein inhibitors. Further, we describe phenotypes of available gene mutants of M. tuberculosis and model organisms Mycobacterium bovis and Mycobacterium smegmatis. We summarize experiments regarding the role of DNA repair-related proteins in pathogenesis and virulence performed both in vitro and in vivo during the infection of macrophages and animals. We detail the role of DNA repair genes in acquiring mutations, which influence the rate of drug resistance acquisition.

A Protective Role of DNA Repair Genes Against Acute Graft Versus Host Disease in Children

Introduction:Acute Graft versus Host Disease (aGvHD) occurs in 20-50% of pediatric patients who undergo allogeneic stem cell transplantation. Despite advances in HLA-typing methods and post-transplant immune suppression, it remains a significant cause of mortality and morbidity. Conditioning regimens include alkylating agents that exert their effects through their ability to directly or indirectly damage DNA. Unfortunately normal cells are also damaged due to their rapid proliferation cycles, increasing the probability of treatment-related toxicities. The most vulnerable targets among these damaged tissues are the skin, the intestinal epithelium, and the liver: In this study, our aim was to find biomarkers for aGvHD by focussing on how inter-individual differences in DNA repair mechanisms due to genetic variants in genes encoding DNA repair proteins might affect toxicity.Methods:The study included 115 children that had undergone allo-HSCT at four different centers. All patients received a Busulfan(Bu)/Cyclophosphamide(Cy) conditioning regimen. Pharmacokinetic-guided dose adjustment was performed for Bu to obtain a concentration at the steady state (Css) between 600 and 900 ng/ml. Patients received 16 doses of Bu followed by, i.v. Cy (200mg/kg total dose, 80% of patients) or CyVP16 (120mg/kg total dose). Cyclosporine was given as GvHD prophylaxis, and Methotrexate (MTX) or steroids were added to bone marrow and cord blood transplantation, respectively. ATG was given to 75% of patients. HLA matching was as follows: MRD = 37%; MUD = 21%; MMRD = 4%; MMUD = 38%. Acute GvHD was diagnosed according to the 1994 consensus conference up to day 180 post HSCT. Peripheral blood was collected and the DNA was extracted prior to transplant. Fifty-one single nucleotide polymorphisms (SNPs) within seventeen DNA repair genes were chosen for investigation. Cumulative incidence analysis of aGvHD 2-4 was performed using Kaplan-Meier analysis and log-rank test. Multivariate Cox regression was performed to estimate the impact of genotype on clinical outcome in the presence of other covariates.Results:The most significant finding came from one SNP (rs10764881, G>A) located in the promoter of the MGMT gene. Patients with rs10764881 GG genotypes had a lower risk for aGvHD 2-4 incidence (Figure 1). This variant was not associated with any other treatment related toxicities nor relapses. Multivariate analysis including MGMT rs10764881 with known aGvHD risk covariates did not influence the model. In addition, from the expression analysis that we performed on 24 lymphoblastoid cell lines rs10764881 GG carriers showed 1.5 fold higher expression compared to AA or AG carriers (Figure 2). We were able to confirm experimentally with luciferase reporter constructs the impact of this variant on promoter function. Plasmids, which included the promoter sequence with rs10764881 demonstrated higher luciferase protein levels, compared to plasmids with a promoter sequence excluding rs10764881 (p= 0.01), suggesting the presence of an enhancement element close to the variant region (Figure 3). Electrophoretic mobility shift assays confirmed the presence of a Glucocorticoid Receptor Element (GRE) near to this variant. To understand whether the enhancing effects are related to corticosteroids, keratinocytes transfected with the gene reporter plasmids were stimulated with dexamethasone and luciferase expression was examined as previously. Exposing the cells with dexamethasone significantly increased protein expression of luciferase in both plasmids compared to their non-treated plasmid construct. The highest response was seen from the plasmid containing variant rs10764881 G (Figure 3). However, clinically we did not find clear differences between steroid and non-steroids recipients against rs10764881 with regards to aGvHD vulnerability (Figure 4).Conclusions:We hypothesize that the reason why variant rs10764881 GG might have a protective effect against aGvHD is due to its higher expression levels, resulting in more efficient DNA repair, in turn diminishing the immune response, reducing inflammation and hence causing less aGvHD. Thus aGvHD rs10764881 GG could potentially be a biomarker for aGvHD protection. The effects of steroids on MGMT expression needs to be addressed in future studies. [Display omitted] DisclosuresBader:Novartis, Medac, Amgen, Riemser, Neovii: Consultancy, Honoraria, Research Funding. Bittencourt:Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Travel Grant; Amgen Inc.: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy.

TEX15: A DNA repair gene associated with prostate cancer risk in Han Chinese.

Both common and rare genetic variants may contribute to risk of developing prostate cancer. Genome-wide association studies (GWASs) have identified ∼100 independent, common variants associated with prostate cancer risk. However, little is known about the association of rare variants (minor allele frequency [MAF] <1%) in the genome with prostate cancer risk. A two-stage study was used to test the association of rare, deleterious coding variants, annotated using predictive algorithms, with prostate cancer risk in Chinese men. Predicted rare, deleterious coding variants in the Illumina HumanExome-12 v1.1 beadchip were first evaluated in 1343 prostate cancer patients and 1008 controls. Significant variants were then validated in an additional 1816 prostate cancer patients and 1549 controls. In the discovery stage, 14 predicted rare, deleterious coding variants were significantly associated with prostate cancer risk (P < 0.01). In the confirmation stage, Q1631H in TEX15 (rs142485241), a DNA repair gene, was significantly associated with prostate cancer risk (P = 0.0069). The estimated odds ratio (OR) of the variant in the combined analysis was 3.24 (95% Confidence Interval 1.85-6.06), P = 8.81 × 10-5 . Additionally, rs28756990 (V741F) at MLH3 (P = 0.06) and rs2961144 (I126V) at OR2A5 (P = 0.065) were marginally associated with prostate cancer risk in the replication stage. Our study provided preliminary evidence that the rare variant Q1631H in DNA repair gene TEX15 is associated with prostate cancer risk. This finding complements known common prostate cancer risk-associated variants and suggests the possible role of DNA repair genes in prostate cancer development.

Expression signatures of DNA repair genes correlate with survival prognosis of astrocytoma patients.

Astrocytomas are the most common primary brain tumors. They are very resistant to therapies and usually progress rapidly to high-grade lesions. Here, we investigated the potential role of DNA repair genes in astrocytoma progression and resistance. To this aim, we performed a polymerase chain reaction array-based analysis focused on DNA repair genes and searched for correlations between expression patters and survival prognoses. We found 19 genes significantly altered. Combining these genes in all possible arrangements, we found 421 expression signatures strongly associated with poor survival. Importantly, five genes (DDB2, EXO1, NEIL3, BRCA2, and BRIP1) were independently correlated with worse prognoses, revealing single-gene signatures. Moreover, silencing of EXO1, which is remarkably overexpressed, promoted faster restoration of double-strand breaks, while NEIL3 knockdown, also highly overexpressed, caused an increment in DNA damage and cell death after irradiation of glioblastoma cells. These results disclose the importance of DNA repair pathways for the maintenance of genomic stability of high-grade astrocytomas and suggest that EXO1 and NEIL3 overexpression confers more efficiency for double-strand break repair and resistance to reactive oxygen species, respectively. Thereby, we highlight these two genes as potentially related with tumor aggressiveness and promising candidates as novel therapeutic targets.

Potential role of dna repair genes in lung cancer development in chromium exposed individuals

Potential role of dna repair genes in lung cancer development in chromium exposed individuals