Abstract 3024: Lack of CK1δ increases DNA damage and genomic instability due to defects in DNA repair and mitotic checkpoints

2015 ◽  
Author(s):  
Yoshimi E. Greer ◽  
Bo Gao ◽  
Yingzi Yang ◽  
Stanley Lipkowitz ◽  
Jeff S. Rubin
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Genomic Instability ◽  
Mitotic Checkpoints

scholarly journals Mechanisms of Genome Maintenance in Plants: Playing It Safe With Breaks and Bumps

2021 ◽  
Vol 12 ◽  
Author(s):  
Aamir Raina ◽  
Parmeshwar K. Sahu ◽  
Rafiul Amin Laskar ◽  
Nitika Rajora ◽  
Richa Sao ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Plant Growth ◽  
Genomic Instability ◽  
Model Organisms ◽  
Ultraviolet Rays ◽  
Genomic Integrity ◽  
Wide Range ◽  
Repair Pathways ◽  
Living Organisms

Maintenance of genomic integrity is critical for the perpetuation of all forms of life including humans. Living organisms are constantly exposed to stress from internal metabolic processes and external environmental sources causing damage to the DNA, thereby promoting genomic instability. To counter the deleterious effects of genomic instability, organisms have evolved general and specific DNA damage repair (DDR) pathways that act either independently or mutually to repair the DNA damage. The mechanisms by which various DNA repair pathways are activated have been fairly investigated in model organisms including bacteria, fungi, and mammals; however, very little is known regarding how plants sense and repair DNA damage. Plants being sessile are innately exposed to a wide range of DNA-damaging agents both from biotic and abiotic sources such as ultraviolet rays or metabolic by-products. To escape their harmful effects, plants also harbor highly conserved DDR pathways that share several components with the DDR machinery of other organisms. Maintenance of genomic integrity is key for plant survival due to lack of reserve germline as the derivation of the new plant occurs from the meristem. Untowardly, the accumulation of mutations in the meristem will result in a wide range of genetic abnormalities in new plants affecting plant growth development and crop yield. In this review, we will discuss various DNA repair pathways in plants and describe how the deficiency of each repair pathway affects plant growth and development.

Genomic instability in cancer: molecular mechanisms and therapeutic potentials

2021 ◽  
Vol 27 ◽  
Author(s):  
Arash Salmaninejad ◽  
Khandan Ilkhani ◽  
Havva Marzan ◽  
Jamshid Gholizadeh Navashenaq ◽  
Samira Rahimirad ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Genomic Instability ◽  
Chromosomal Instability ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Dna Damages ◽  
Replication Errors ◽  
Repair Mechanisms ◽  
Dna Replication Errors

: DNA damage usually happens in all cell types, which may originate from endogenous sources, (i.e., DNA replication errors) or be emanated from radiations or chemicals. These damages range from changes in few nucleotides to large structural abnormalities on chromosomes and, if not repaired, could disturb the cellular homeostasis or cause cell death. DNA repair, as the most significant response to DNA damage, provides biological pathways by which DNA damages are corrected and returned into their natural circumstance. However, aberration in the DNA repair mechanisms may result in genomic and chromosomal instability and the accumulation of mutations. The activation of oncogenes and/or inactivation of tumor suppressor genes are serious consequence of genomic and chromosomal instability and may bring the cells into a cancerous phenotype. Therefore, genomic and chromosomal instability is usually considered as a crucial factor in the carcinogenesis and an important hallmark of various human malignancies. In the present study, we review our current understanding of the most updated mechanisms underlying genomic instability in cancer and discuss about the potential promises of these mechanisms in finding new targets for the treatment of cancer.

Role Of Sirtuin-6 In Maintenance Of Genomic Instability In Multiple Myeloma Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 276-276
Author(s):  
Michele Cea ◽  
Antonia Cagnetta ◽  
Mariateresa Fulciniti ◽  
Yu-Tzu Tai ◽  
Chirag Acharya ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Dna Damage ◽  
Dna Repair ◽  
Genomic Instability ◽  
Cell Lines ◽  
Dsb Repair ◽  
Dna Damaging Agents ◽  
Genotoxic Agents ◽  
Equity Ownership

Abstract Background Deregulation of the DNA damage response (DDR) signaling machinery underlies genomic instability, leading to cancer development and clonal evolution. Multiple Myeloma (MM) remains an incurable disease characterized by a highly unstable genome, with aneuploidy observed in nearly all patients. The mechanism causing this karyotypic instability is largely unknown, but recent observations have correlated these abnormalities with dysfunctional DDR machinery. Mammalian NAD+-dependent deacetylase sirtuin-6 (SIRT6) is emerging as new protein involved in multiple pathways, including maintenance of genome integrity. Methods A panel of 18 MM cell lines, both sensitive and resistant to conventional and novel anti-MM therapies, was used in this study. Blood and BM samples from healthy volunteers and MM patients were obtained after informed consent and mononuclear cells (MNCs) separated by Ficoll-Paque density sedimentation. Patient MM cells were isolated from BM MNCs by CD138-positive selection. Lentiviral delivery was used for expression and knock-down of SIRT6 in MM cell lines. The biologic impact of SIRT6 phenotype was evaluated using cell growth, viability and apoptosis assays. DNA Double-Strand Breaks (DSB) repair occurring via homologous recombination (HR) or non-homologous end-joining (NHEJ) pathways was assessed using a transient direct repeat (DR)-GFP/I-SceI system. Results A comparative gene expression analysis of 414 newly-diagnosed uniformly-treated MM patients showed high levels of SIRT6 mRNA in MM patients versus MGUS or normal donors; moreover, in active MM elevated SIRT6 expression correlated with adverse clinical outcome. Due to its prognostic significance, we further evaluated its role in MM biology. We found higher SIRT6 nuclear expression in MM cell lines and primary cells compared to PBMCs from healthy donors. Targeting SIRT6 by specific shRNA increased MM cell survival by reducing DNA repair efficiency (HR and NHEJ). Whole genome profiling of three different SIRT6 knockout (Sirt6-/-) MM cell lines identified a restricted effect of SIRT6 silencing on transcription of DNA damage genes, which also represented the most down-regulated genes. Consistent with these data, GSEA algorithm revealed that gene set regulating DNA repair were prominently enriched in SIRT6 depleted cells (p<0.0001 and FDR=0.003), confirming the role of SIRT6 in this pathway. We next examined the therapeutic relevance of SIRT6 inhibition in MM by evaluating the effect of SIRT6 depletion on cytotoxicity induced by genotoxic agents. SIRT6 shRNA impaired DNA DSB repair pathways triggered by DNA damaging agents, thereby enhancing overall anti-MM activity of these agents. Finally, in concert with our in vitro data, studies using our human MM xenograft model confirmed that SIRT6 depletion enhanced anti-MM activity of DNA-damaging agents. Conclusion Collectively, our data provide basis for targeting SIRT6 as a novel therapeutic strategy in combination with genotoxic agents to enhance cytotoxicity and improve patient outcome in MM. Disclosures: Tai: Onyx: Consultancy. Hideshima:Acetylon Pharmaceuticals: Consultancy. Chauhan:Vivolux: Consultancy. Anderson:celgene: Consultancy; onyx: Consultancy; gilead: Consultancy; sanofi aventis: Consultancy; oncopep: Equity Ownership; acetylon: Equity Ownership.

scholarly journals DNA Damage as a Driver for Growth Delay: Chromosome Instability Syndromes with Intrauterine Growth Retardation

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Benilde García-de Teresa ◽  
Mariana Hernández-Gómez ◽  
Sara Frías
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Genomic Instability ◽  
Growth Retardation ◽  
Cellular Response ◽  
Intrauterine Growth Retardation ◽  
Chromosome Instability ◽  
Genetic Material ◽  
Lesion Detection ◽  
Intrauterine Growth

DNA is constantly exposed to endogenous and exogenous mutagenic stimuli that are capable of producing diverse lesions. In order to protect the integrity of the genetic material, a wide array of DNA repair systems that can target each specific lesion has evolved. Despite the availability of several repair pathways, a common general program known as the DNA damage response (DDR) is stimulated to promote lesion detection, signaling, and repair in order to maintain genetic integrity. The genes that participate in these pathways are subject to mutation; a loss in their function would result in impaired DNA repair and genomic instability. When the DDR is constitutionally altered, every cell of the organism, starting from development, will show DNA damage and subsequent genomic instability. The cellular response to this is either uncontrolled proliferation and cell cycle deregulation that ensues overgrowth, or apoptosis and senescence that result in tissue hypoplasia. These diverging growth abnormalities can clinically translate as cancer or growth retardation; both features can be found in chromosome instability syndromes (CIS). The analysis of the clinical, cellular, and molecular phenotypes of CIS with intrauterine growth retardation allows inferring that replication alteration is their unifying feature.

scholarly journals MYBL2-Driven Transcriptional Programs Link Replication Stress and Error-prone DNA Repair With Genomic Instability in Lung Adenocarcinoma

2021 ◽  
Vol 10 ◽  
Author(s):  
Benjamin B. Morris ◽  
Nolan A. Wages ◽  
Patrick A. Grant ◽  
P. Todd Stukenberg ◽  
Ryan D. Gentzler ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Transcription Factor ◽  
Lung Adenocarcinoma ◽  
Genomic Instability ◽  
Replication Stress ◽  
Omics Data ◽  
Repair Pathways ◽  
Lung Adenocarcinomas

It has long been recognized that defects in cell cycle checkpoint and DNA repair pathways give rise to genomic instability, tumor heterogeneity, and metastasis. Despite this knowledge, the transcription factor-mediated gene expression programs that enable survival and proliferation in the face of enormous replication stress and DNA damage have remained elusive. Using robust omics data from two independent studies, we provide evidence that a large cohort of lung adenocarcinomas exhibit significant genome instability and overexpress the DNA damage responsive transcription factor MYB proto-oncogene like 2 (MYBL2). Across two studies, elevated MYBL2 expression was a robust marker of poor overall survival and disease-free survival outcomes, regardless of disease stage. Clinically, elevated MYBL2 expression identified patients with aggressive early onset disease, increased lymph node involvement, and increased incidence of distant metastases. Analysis of genomic sequencing data demonstrated that MYBL2 High lung adenocarcinomas had elevated somatic mutation burden, widespread chromosomal alterations, and alterations in single-strand DNA break repair pathways. In this study, we provide evidence that impaired single-strand break repair, combined with a loss of cell cycle regulators TP53 and RB1, give rise to MYBL2-mediated transcriptional programs. Omics data supports a model wherein tumors with significant genomic instability upregulate MYBL2 to drive genes that control replication stress responses, promote error-prone DNA repair, and antagonize faithful homologous recombination repair. Our study supports the use of checkpoint kinase 1 (CHK1) pharmacological inhibitors, in targeted MYBL2 High patient cohorts, as a future therapy to improve lung adenocarcinoma patient outcomes.

scholarly journals Genomic Instability and Cancer Risk Associated with Erroneous DNA Repair

2021 ◽  
Vol 22 (22) ◽  
pp. 12254
Author(s):  
Ken-ichi Yoshioka ◽  
Rika Kusumoto-Matsuo ◽  
Yusuke Matsuno ◽  
Masamichi Ishiai
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Cancer Risk ◽  
Genomic Instability ◽  
Double Strand Breaks ◽  
Genomic Rearrangements ◽  
Repair Pathway ◽  
Dna Double Strand Breaks ◽  
Brca1 And Brca2 ◽  
Strand Breaks

Many cancers develop as a consequence of genomic instability, which induces genomic rearrangements and nucleotide mutations. Failure to correct DNA damage in DNA repair defective cells, such as in BRCA1 and BRCA2 mutated backgrounds, is directly associated with increased cancer risk. Genomic rearrangement is generally a consequence of erroneous repair of DNA double-strand breaks (DSBs), though paradoxically, many cancers develop in the absence of DNA repair defects. DNA repair systems are essential for cell survival, and in cancers deficient in one repair pathway, other pathways can become upregulated. In this review, we examine the current literature on genomic alterations in cancer cells and the association between these alterations and DNA repair pathway inactivation and upregulation.

BCR/ABL Kinase Elevates ROS-Mediated Oxidative DNA Damage in CML Stem/Progenitor Cells and Affects the Efficiency and Fidelity of DNA Repair To Induce Genetic Instability.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 34-34
Author(s):  
Margaret Nieborowska-Skorska ◽  
Artur Slupianek ◽  
Tomasz Stoklosa ◽  
Tomasz Poplawski ◽  
Kimberly Cramer ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Genomic Instability ◽  
Chromosomal Aberrations ◽  
Oxidative Dna Damage ◽  
Point Mutations ◽  
Dna Lesions ◽  
Leukemia Cells ◽  
Abl Kinase ◽  
Imatinib Resistant

Abstract BCR/ABL kinase transforms hematopoietic stem cells (HSCs) to induce chronic myelogenous leukemia in chronic phase (CML-CP), which eventually evolves into fatal blast crisis (CML-BC). CML is a stem cell-derived but a progenitor-driven disease. In CML-CP leukemia stem (LSCs) and progenitor (LPCs) cells reside in CD34+CD38− and CD34+CD38+ populations, respectively, whereas in CML-BC LSCs are found also in CD34+CD38+ population. BCR/ABL kinase stimulates genomic instability causing imatinib-resistant point mutations and chromosomal aberrations associated with progression to CML-BC. Genomic instability may result from enhanced DNA damage and/or aberrant DNA repair mechanisms. We showed that CD34+ stem/progenitor CML cells contain higher levels of reactive oxygen species (ROS) than these from healthy donors (CML-BC>CML-CP>Normal). In addition, ROS were elevated in CD34+CD38− and CD34+CD38+ sub-populations isolated from CML-BC and CML-CP patients in comparison to cells from healthy donor. Higher ROS levels induced more oxidative DNA lesions such as oxidized bases (e.g., 8-oxoG) and DNA double-strand breaks (DSBs). ROS and oxidative DNA damage in CML stem/progenitor cells could be diminished by an antioxidant N-acetyl-cysteine. Moreover, inhibition of ROS by vitamin E reduced the frequency of imatinib-resistant BCR/ABL point mutants and chromosomal aberrations in leukemia cells in SCID mice. Cellular DNA repair systems act to remove DNA damage and ultimately preserve the informational integrity of the genome. Base excision repair (BER) and mismatch repair (MMR) are responsible for removal of oxidized bases. BER was assessed using single- and double-stranded DNA substrates containing 5-OH-U (a derivative of ROS-damaged hydroxy-deoxycytidine). MMR activity was measured by restoration of the expression of GFP from the construct containing T-G mismatch in the start codon. BCR/ABL kinase severely inhibited BER and MMR in cell lines and CD34+ CML cells, and promoted accumulation of point mutations in genes encoding BCR/ABL kinase and Na+/K+ ATPase. Inhibition of BCR/ABL kinase by imatinib restored BER and MMR activities. Oxidized bases, if not repaired, may lead to accumulation of DSBs observed in LSCs and LPCs. DSBs may be processed by homologous recombination (HR), non-homologous and-joininig (NHEJ), and single-strand annealing (SSA). HR represents faithful repair, NHEJ usually produces small deletions, and SSA causes very large deletions. Genome-integrated repair-specific reporter cassettes containing two disrupted fragments of the gene encoding GFP were used where a single DSB induced by I-SceI endonuclease in one of the fragments stimulated HR, NHEJ, or SSA. In general, BCR/ABL kinase enhanced DSBs repair activities, however at the expense of their fidelity. Numerous point mutations were introduced in HR repair products. NHEJ generated larger than usual deletions. SSA, rather rare but very unfaithful, was also induced in BCR/ABL-positive leukemia cells. In summary, BCR/ABL kinase enhanced ROS-mediated oxidative DNA damage in LSCs and LPCs. In addition, BCR/ABL inhibited BER and MMR of usually non-lethal oxidized DNA lesions leading to accumulation of point mutations. Moreover, BCR/ABL kinase stimulated HR, NHEJ and SSA of lethal DSBs, but compromised the fidelity of repair.

Apurinic/Apyrimidinic Endonuclease 1 Induced Genomic Instability Causes T-Cell Acute Lymphoblastic Leukemia in Zebrafish

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1431-1431
Author(s):  
Jianhong Lin ◽  
Chun Yang ◽  
Ariel Kwart ◽  
Jianjun Zhao ◽  
Mehmet K Samur ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Genomic Instability ◽  
Lymphoblastic Leukemia ◽  
Transgenic Zebrafish ◽  
Advisory Committees ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Equity Ownership ◽  
Lymphoblastic Cells

Abstract Genomic instability is not only a hallmark of cancer, but potentially a primary mechanism for its occurrence. DNA repair mechanisms play a protective role during DNA damage induced by both normal metabolic activities and environmental factors such as reactive oxygen species (ROS), UV light and γ-irradiation. Genes related to DNA repair are usually considered as tumor suppressors. However, incomplete repair may induce severe genomic instability, leading eventually to transformation. Apurinic/apyrimidinic endonuclease 1 (APEX1), a gene involved in DNA repair with an important role in the base excision repair pathway, leads to transformation of normal cells in vitro. To investigate the role of APEX1 in tumor initiation in vivo, we generated a novel transgenic zebrafish model to overexpress APEX1 in fish. Specifically, pDestTol2A2_ubi:loxP-EGFP-loxP-APEX1-mCherry plasmid was injected into single cell embryos derived from the TP53 mutant line Tp53M214K/M214K to generate a stable conditional inducible transgenic zebrafish line: Tg:APEX1fl/- mCherry Tp53M214K/M214K. To activate APEX1 expression in vivo, this line was mated with Tg:HSP70-Cre+/+ fish. Compound zebrafish Tg: APEX1fl/- mCherry,Tp53+/M214K ,HSP70-Cre+/- carrying a Cre-activatable APEX1 knock-in allele were heated at 24hpf, and induction of APEX1 expression was monitored by downstream reporter - mCherry expression. Ten to twelve months post-fertilization, Tg:APEX1fl/- mCherry,Tp53+/M214K ,HSP70-Cre+/- fish developed abnormal swelling. Flow cytometry analysis of fish kidney marrow and peripheral blood showed dramatically increased precursor populations in scatter analysis. Histopathologic analysis showed that multiple organs were infiltrated with malignant lymphoblastic cells. None of the control fish Tg: GFP,Tp53+/M214K ,HSP70-Cre+/- developed tumors during their life span. Zebrafish with T-ALL have heterozygous Tp53+/M214K background, but the expression of p21, mdm2 and bax in Tp53+/M214K fish is exactly the same as in Tp53+/+ fish; and Tp53+/M214K zebrafish themselves have not developed tumors during their life span. RNA from lymphoblastic cells was evaluated by qRT-PCR and showed increased expression of CD3, LCK and Tal indicating a T-cell acute lymphoblastic leukemia/lymphoma (T-ALL). We have performed whole genomic DNA sequencing in extracted DNA from fish tumor cells and compared it with their normal counterpart and observed multiple copy number changes and mutations. We have now begun to see the development of other tumors in other organs including the eye and the testis. To uncover the molecular mechanism of tumorigenesis induced by APEX1, we have performed Mass Spectrometry analysis on APEX1 pulled down from 293T and AG08498 cells ectopically expressing APEX1. Besides verified binding proteins, such as PCNA, we also identified Ku70 and Ku80 binding to APEX1 directly. Further immunoflurescent staining and confocal microscopy of 293T cells also found co-localization of APEX1 and Ku70/Ku80. Those two proteins initiate Non-Homologous End Joining (NHEJ) repair and start the error-prone double strand repair and DNA damage. These results indicate that excessive repair activity may induce DNA damage and genomic instability. In summary, this is the first demonstration where overexpression of a DNA repair gene is responsible for induction of genomic instability leading to malignant transformation. It provides new insight into the process of tumorigenesis and development of both therapy as well as preventive strategies. Disclosures Zon: FATE Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Founder; Scholar Rock: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Founder.

scholarly journals High Temperature Drives Topoisomerase Mediated Chromosomal Break Repair Pathway Choice

Cancers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 2315
Author(s):  
Mohamed E. Ashour ◽  
Walaa Allam ◽  
Waheba Elsayed ◽  
Reham Atteya ◽  
Menattallah Elserafy ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Protective Effect ◽  
Genomic Instability ◽  
Double Strand Breaks ◽  
Acute Exposure ◽  
Repair Pathway ◽  
Strand Breaks ◽  
Topoisomerase Poisons ◽  
Chromosomal Break

Cancer-causing mutations often arise from inappropriate DNA repair, yet acute exposure to DNA damage is widely used to treat cancer. The challenge remains in how to specifically induce excessive DNA damage in cancer cells while minimizing the undesirable effects of genomic instability in noncancerous cells. One approach is the acute exposure to hyperthermia, which suppresses DNA repair and synergizes with radiotherapy and chemotherapy. An exception, however, is the protective effect of hyperthermia on topoisomerase targeting therapeutics. The molecular explanation for this conundrum remains unclear. Here, we show that hyperthermia suppresses the level of topoisomerase mediated single- and double-strand breaks induced by exposure to topoisomerase poisons. We further uncover that, hyperthermia suppresses hallmarks of genomic instability induced by topoisomerase targeting therapeutics by inhibiting nuclease activities, thereby channeling repair to error-free pathways driven by tyrosyl-DNA phosphodiesterases. These findings provide an explanation for the protective effect of hyperthermia from topoisomerase-induced DNA damage and may help to explain the inverse relationship between cancer incidence and temperature. They also pave the way for the use of controlled heat as a therapeutic adjunct to topoisomerase targeting therapeutics.

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