scholarly journals Leukemia Stem Cells Demonstrate Increased DNA Damage Repair and Chemoresistance in Acute Myeloid Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 2-2
Author(s):  
Grace Egan ◽  
Geethu Emily Thomas ◽  
Parasvi Patel ◽  
Rose Hurren ◽  
Neil MacLean ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Dna Repair ◽  
Stem Cell ◽  
Dna Damage Repair ◽  
Leukemia Stem Cells ◽  
Over Expression ◽  
Γh2ax Foci ◽  
Damage Repair ◽  
Repair Genes

While most patients with AML achieve remission with standard induction chemotherapy, the majority ultimately relapse. Relapsed AML is due, at least in part, to the persistence of chemoresistant leukemia stem cells (LSCs). The mechanisms of chemoresistance in LSCs are not fully understood. Here, we explored DNA damage repair in LSCs. 8227 cells are low passage primary AML cells that maintain a hierarchical organization with functionally defined stem cells in the CD34+CD38- fraction. We FACS sorted 8227 cells into stem and bulk fractions and measured expression of DNA repair genes. LSCs were primed for DNA repair with increased expression of genes associated with homologous recombination (RAD51, XRCC2, XRCC3) and non-homologous end joining (XRCC4, XRCC5, PRKDC). Next, we treated the cell fractions with daunorubicin, an intercalating anthracycline that causes double stranded breaks. DNA damage and repair were evaluated by measuring foci of 53BP1, RAD51 and γH2AX by fluorescent microscopy and quantified using image J. Compared to bulk cells, 8227 stem cells demonstrated enhanced DNA damage repair with increased foci of 53BP1 and RAD51 and decreased γH2AX foci, compared to their basal levels. Similar findings were noted after exposing the stem and bulk cells to radiation. We recently discovered that the metabolic enzyme hexokinase 2 (HK2) localizes to the nucleus to maintain stem cell number and function. Therefore, we selectively over-expressed HK2 in the nucleus of 8227 and NB4 cells by tagging HK2 with a nuclear localizing sequence (PAAKRVKLD). We confirmed selective over-expression of HK2 in the nucleus by immunoblotting and confocal microscopy. Over-expressing HK2 increased stem cell function as shown by clonogenic growth assays and engraftment into mouse marrow. We then treated these cells with daunorubicin and measured DNA damage repair. Over-expression of nuclear HK2 increased 53BP1 and RAD51 foci with decreased γH2AX foci, similar to the phenotype observed in LSCs. In addition, over-expression of nuclear HK2 conferred resistance to daunorubicin as measured by clonogenic growth assays. In summary, LSCs appear to be primed for DNA repair with increased levels of DNA damage repair genes. After exposure to chemotherapy and radiation, LSCs have increased repair of double strand DNA breaks compared to more differentiated blasts. This accelerated DNA damage repair may partly explain the increased chemoresistance seen in LSCs. Disclosures Schimmer: Takeda:Honoraria, Research Funding;Novartis:Honoraria;Jazz:Honoraria;AbbVie Pharmaceuticals:Other: owns stock ;Otsuka:Honoraria;Medivir AB:Research Funding.

scholarly journals The Tardigrade Damage Suppressor Protein Promotes Transcription Factor Activation and Expression of DNA Repair Genes in Human Cells in Response to Hydroxyl Radicals and UV-C Exposure

2021 ◽  
Author(s):  
Claudia Ricci ◽  
Giulia Riolo ◽  
Carlotta Marzocchi ◽  
Jlenia Brunetti ◽  
Alessandro Pini ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Expression Patterns ◽  
Dna Damage Repair ◽  
Human Cells ◽  
H2o2 Treatment ◽  
Damage Repair ◽  
Transcription Factor Activation ◽  
Uv C ◽  
Repair Genes

The Ramazzottius varieornatus tardigrade is an extremotolerant terrestrial invertebrate belonging to the phylum of Tardigrada. At a length of 0.1-1.0 mm, tardigrades are small animals with an exceptional tolerance to extreme conditions such as high pressure, chemicals and irradia-tion. These properties have been attributed to the recently-discovered Dsup protein. Dsup is a nucleosome-binding protein that prevents DNA damage against X-ray and oxidative stress without impairing cell life, also in Dsup-transfected animal and plant cells. However, the precise “protective” role of this protein is still under study. We performed experiments on human cells and shows that, as compared to control cells, Dsup+ cells are more resistant to UV-C exposure and H2O2. Real-time PCR identified different expression patterns of endogenous genes involved in apoptosis, cell survival and DNA damage repair in Dsup+ cells in response to H2O2 and UV-C. While H2O2 treatment in Dsup+ cells only marginally involved the activation of pathways responsible for DNA repair reinforcing the idea of a direct protective effect of the protein on DNA, in UV-C exposed cells, Dsup efficiently upregulates DNA damage repair genes. In conclusion, our data may help to delineate the different mechanisms by which the Dsup protein operates in response to different insults.

scholarly journals Abstract 3098: Leukemia stem cells demonstrate enhanced DNA damage repair and chemoresistance in AML

2021 ◽  
Author(s):  
Grace Egan ◽  
G.E. Thomas ◽  
Parasvi Patel ◽  
Veronique Voisin ◽  
Rose Hurren ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Dna Damage Repair ◽  
Leukemia Stem Cells ◽  
Damage Repair

In Vitro Senescence of Rat Mesenchymal Stem Cells is Accompanied by Downregulation of Stemness-Related and DNA Damage Repair Genes

2009 ◽  
Vol 18 (7) ◽  
pp. 1033-1042 ◽  
Author(s):  
Umberto Galderisi ◽  
Heike Helmbold ◽  
Tiziana Squillaro ◽  
Nicola Alessio ◽  
Natascha Komm ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Mesenchymal Stem Cells ◽  
Dna Damage Repair ◽  
Damage Repair ◽  
Repair Genes

scholarly journals O2: TOWARDS A LIVING BIOBANK OF SURGICALLY-RELEVANT 3-DIMENSIONAL GLIOBLASTOMA STEM CELL MODELS TO EVALUATE NOVEL THERAPEUTICS AND INTERROGATE INTRATUMOURAL HETEROGENEITY

2021 ◽  
Vol 108 (Supplement_1) ◽  
Author(s):  
O Rominiyi ◽  
A Vanderlinden ◽  
K Myers ◽  
N Gomez-Roman ◽  
D Dar ◽  
...  
Keyword(s):  
Dna Damage ◽  
Stem Cell ◽  
Cancer Biology ◽  
Residual Disease ◽  
Dna Damage Repair ◽  
Stem Cell Marker ◽  
Left Behind ◽  
Glioblastoma Stem Cell ◽  
Damage Repair ◽  
Intratumoural Heterogeneity

Abstract Introduction Glioblastoma is the most common cancer arising within the brain. Despite surgery, followed by DNA-damaging chemoradiotherapy, average survival remains between 12-15 months. Unacceptable survival rates underline the need to develop preclinical research models which recapitulate features underpinning therapeutic resistance in patients, such as intratumoural heterogeneity and treatment resistant glioblastoma stem cell (GSC) subpopulations which demonstrate elevated DNA damage response (DDR) activity. Method Tumour specimens from patients were used to generate 2D and 3D scaffold-based GSC models, with a range of preclinical survival and molecular assays used to interrogate cancer biology and assess therapeutic responses. Result We have developed a ‘living biobank’ of 20+ ex-vivo GSC models which reflect key clinicopathological diversity. These models include residual disease models based on careful macrodissection of rare en-blocpartial lobectomy specimens to liberate parallel GSC lines from the tumour core and adjacent infiltrated brain, to represent cells typically left behind after surgery. Therapeutic strategies targeting fundamental DDR processes demonstrate preclinical efficacy, for example dual inhibition of ATR and the FA DNA damage repair pathways elicits profound radiosensitisation (sensitiser enhancement ratio of 3.23 (3.03-3.49, 95%-CI)) with evidence of delayed DNA damage repair on single-cell gel electrophoresis. Finally, characterisation of our surgically-relevant resected and residual models reveals numerous divergent properties including elevated stem cell marker expression in residual models (p=0.0021), which may partially explain treatment resistance in disease left behind after surgery. Conclusion Our living biobank represents a useful resource for preclinical glioblastoma research and demonstrates the value of partnership between surgeons and laboratory-based scientists. Take-home message Our living biobank represents a useful resource for preclinical glioblastoma research and demonstrates the value of partnership between surgeons and laboratory-based scientists.

scholarly journals P57.04 Mutations of DNA Damage Repair Genes in Lung Adenocarcinoma and Their Association with Actionable Alterations

2021 ◽  
Vol 16 (3) ◽  
pp. S534-S535
Author(s):  
Z. Yu ◽  
S. Dang ◽  
J. Zhang ◽  
J. Duan ◽  
S. Chen ◽  
...  
Keyword(s):  
Dna Damage ◽  
Lung Adenocarcinoma ◽  
Dna Damage Repair ◽  
Damage Repair ◽  
Repair Genes

scholarly journals MicroRNA-146a-5p enhances radiosensitivity in hepatocellular carcinoma through replication protein A3-induced activation of the DNA repair pathway

2019 ◽  
Vol 316 (3) ◽  
pp. C299-C311 ◽  
Author(s):  
Jing Luo ◽  
Zhong-Zhou Si ◽  
Ting Li ◽  
Jie-Qun Li ◽  
Zhong-Qiang Zhang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Proliferation ◽  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Repair ◽  
Replication Protein ◽  
Repair Pathway ◽  
Related Factors ◽  
Damage Repair ◽  
Hcc Cells

Hepatocellular carcinoma (HCC) is known for its high mortality rate worldwide. Based on intensive studies, microRNA (miRNA) expression functions in tumor suppression. Therefore, we aimed to evaluate the contribution of miR-146a-5p to radiosensitivity in HCC through the activation of the DNA damage repair pathway by binding to replication protein A3 (RPA3). First, the limma package of R was performed to differentially analyze HCC expression chip, and regulative miRNA of RPA3 was predicted. Expression of miR-146a-5p, RPA3, and DNA damage repair pathway-related factors in tissues and cells was determined. The effects of radiotherapy on the expression of miR-146a-5p and RPA3 as well as on cell radiosensitivity, proliferation, cell cycle, and apoptosis were also assessed. The results showed that there exists a close correlation between miR-146a and the radiotherapy effect on HCC progression through regulation of RPA3 and the DNA repair pathway. The positive rate of ATM, pCHK2, and Rad51 in HCC tissues was higher when compared with that of the paracancerous tissues. SMMC-7721 and HepG2 cell proliferation were significantly inhibited following 8 Gy 6Mv dose. MiR-146a-5p restrained the expression of RPA3 and promoted the expression of relative genes associated with the DNA repair pathway. In addition, miR-146a-5p overexpression suppresses cell proliferation and enhances radiosensitivity and cell apoptosis in HCC cells. In conclusion, the present study revealed that miR-146a-5p could lead to the restriction of proliferation and the promotion of radiosensitivity and apoptosis in HCC cells through activation of DNA repair pathway and inhibition of RPA3.

scholarly journals Differentiation of Human Induced Pluripotent or Embryonic Stem Cells Decreases the DNA Damage Repair by Homologous Recombination

2017 ◽  
Vol 9 (5) ◽  
pp. 1660-1674 ◽  
Author(s):  
Kalpana Mujoo ◽  
Raj K. Pandita ◽  
Anjana Tiwari ◽  
Vijay Charaka ◽  
Sharmistha Chakraborty ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Embryonic Stem Cells ◽  
Homologous Recombination ◽  
Dna Damage Repair ◽  
Embryonic Stem ◽  
Damage Repair ◽  
Induced Pluripotent

scholarly journals DISTRIBUTION OF DNA DAMAGE REPAIR GENE POLYMORPHISM hOGG1, XRCC1 and p53 AMONG SICKLE CELL DISEASE PATIENTS IN INDIA

2015 ◽  
Vol 7 ◽  
pp. e2015046 ◽  
Author(s):  
Sudhansu Sekhar Nishank
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Sickle Cell Disease ◽  
Gene Polymorphisms ◽  
Clinical Effect ◽  
Dna Damage Repair ◽  
Cell Disease ◽  
Repair Gene ◽  
Damage Repair ◽  
Repair Genes

Background– Defect in DNA damage repair genes due to oxidative stress predispose the humans to malignancies. There are many cases of association of malignancies with sickle cell disease patients (SCD) throughout the world, the molecular cause of which has never been investigated. DNA damage repair genes such as  hOGG1, XRCC1 and p53 play significant role in repair of DNA damage during oxidative stress but the distribution and clinical effect of these genes are not known till date in SCD patients who are associated with oxidative stress related clinical complications.        Objective – The aim of the study was to characterize the distribution and clinical effect of DNA damage gene polymorphisms p53 (codon 72 Arg> Pro), hOGG1 (codon 326 Ser>Cyst) and XRCC1 (codons 194 Arg>Trp, codon 280 Arg> His, codon 399 Arg> Gln) among SCD patients of  central India. Methods- A case control study of  250 SCD patients and 250 normal individuals were investigated by PCR-RFLP techniques.     Result- The prevalence of mutant alleles of hOGG1 gene, XRCC1 codon 280 Arg>His  were found to be significantly high among SCD patients as compared to controls. However, SCD patients did not show clinical association with any of these DNA repair gene polymorphisms.  Conclusion- This indicates that hOGG1, p53  and XRCC1 gene polymorphisms  may not have any clinical impact among SCD patients in India.

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