scholarly journals TEL/JAK2 tyrosine kinase inhibits DNA repair in the presence of amifostine.

2002 ◽  
Vol 49 (1) ◽  
pp. 121-128 ◽  
Author(s):  
Ewa Gloc ◽  
Mariusz Warszawski ◽  
Wojciech Młynarski ◽  
Małgorzata Stolarska ◽  
Grazyna Hoser ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Tyrosine Kinase ◽  
Cellular Response ◽  
Catalytic Domain ◽  
Lymphoblastic Leukemia ◽  
Chromosomal Translocation ◽  
Cell Types ◽  
Transformed Cells ◽  
Dna Damage And Repair

The TEL/JAK2 chromosomal translocation (t(9;12)(p24;p13)) is associated with T cell childhood acute lymphoblastic leukemia. The TEL/JAK2 fusion protein contains the JAK2 catalytic domain and the TEL-specific oligomerization domain. TEL-mediated oligomerization of the TEL/JAK2 proteins results in the constitutive activation of the tyrosine kinase activity. Leukemia cells expressing TEL/JAK2 tyrosine kinase become resistant to anti-neoplastic drugs. Amifostine is a pro-drug which can selectively protect normal tissues against the toxicity of anticancer drugs and radiation. We investigated the effects of amifostine on idarubicin-induced DNA damage and repair in murine pro-B lymphoid BaF3 cells and BaF3-TEL/JAK2-transformed cells using alkaline single cell gel electrophoresis (comet assay). Idarubicin induced DNA damage in both cell types but amifostine reduced its extent in control non-transformed BaF3 cells and enhanced it in TEL/JAK2-transformed cells. The transformed cells did not show measurable DNA repair after exposure to amifostine and idarubicin, but cells treated only with idarubicin were able to recover within a 60-min incubation. Because TEL/JAK2-transformed cells can be considered as model cells for certain human leukemias and lymphomas we anticipate an enhancement of idarubicin cytotoxicity by amifostine in these diseases. Moreover, TEL/JAK2 tyrosine kinase might be involved in cellular response to DNA damage. Amifostine could promote apoptosis or lower the threshold for apoptosis induction dependent on TEL/JAK2 activation.

The Effects of BCR/ABL on DNA Damage and Repair Are Dependent on Apoptosis Competence

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4216-4216
Author(s):  
Beth A Burke ◽  
Martin Carroll
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Tyrosine Kinase ◽  
Cell Line ◽  
Chromosomal Abnormalities ◽  
Chronic Phase ◽  
Genotoxic Stress ◽  
Second Phase ◽  
Similar Amount ◽  
Dna Damage And Repair

Abstract Chronic myeloid leukemia (CML) is a two-stage disease associated with the t(9;22) translocation. This translocation fuses the BCR gene with the ABL tyrosine kinase, forming the BCR/ABL oncogene. BCR/ABL is a constitutively activated tyrosine kinase, which causes the first stage of CML, chronic phase. However, it is still unknown why patients progress to the second phase, blast crisis, a phase marked by increased chromosomal abnormalities. Previous data from our lab suggests that cells expressing BCR/ABL have an increase in chromosomal translocations after DNA repair compared to control cells, as assessed by spectral karyotyping. We hypothesized that BCR/ABL alters the apoptotic threshold in response to DNA damage, and we sought to determine if cells lacking BCR/ABL that were unable to undergo apoptosis would show similar responses in DNA damage and repair assays to BCR/ABL expressing cells. In order to study this question we have used an interleukin 3 (IL3) dependent cell line that lacks expression of the pro-apoptotic proteins, Bax and Bak. These cells grow in the presence of IL3 but do not undergo apoptosis after cytokine withdrawal or genotoxic stress. We have generated a subclone of these cells that expresses BCR/ABL. This cell line, designated DBA, grows in the absence of IL3. As expected, growth of the cells in the absence of IL3 is suppressed by the ABL kinase inhibitor, dasatinib. BCR/ABL expressing and control cells proliferate at similar rates following DNA damage. After damage, both control cells and DBA cells have a delay in the G2/M phase of the cell cycle, which is modestly prolonged in BCR/ABL expressing cells. Both control and BCR/ABL expressing cells have a similar amount of DNA damage after irradiation as assessed by pulsed field gel electrophoresis. Additionally, the rate of repair of DNA double strand breaks is not significantly different in the two cell types. Spectral karyotype analysis is ongoing to determine whether error prone DNA repair in BCR/ABL cells is secondary to the effects of BCR/ABL on inhibition of apoptosis or reflects other proposed mechanisms of action of the oncogene.

scholarly journals Veliparib Is an Effective Radiosensitizing Agent in a Preclinical Model of Medulloblastoma

2021 ◽  
Vol 8 ◽  
Author(s):  
Jessica Buck ◽  
Patrick J. C. Dyer ◽  
Hilary Hii ◽  
Brooke Carline ◽  
Mani Kuchibhotla ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Combination Therapy ◽  
Cellular Response ◽  
Molecular Subtype ◽  
Parp Inhibitor ◽  
Single Agent ◽  
Parp Inhibition ◽  
Preclinical Model ◽  
Radiation Induced

Medulloblastoma is the most common malignant childhood brain tumor, and 5-year overall survival rates are as low as 40% depending on molecular subtype, with new therapies critically important. As radiotherapy and chemotherapy act through the induction of DNA damage, the sensitization of cancer cells through the inhibition of DNA damage repair pathways is a potential therapeutic strategy. The poly-(ADP-ribose) polymerase (PARP) inhibitor veliparib was assessed for its ability to augment the cellular response to radiation-induced DNA damage in human medulloblastoma cells. DNA repair following irradiation was assessed using the alkaline comet assay, with veliparib inhibiting the rate of DNA repair. Veliparib treatment also increased the number of γH2AX foci in cells treated with radiation, and analysis of downstream pathways indicated persistent activation of the DNA damage response pathway. Clonogenicity assays demonstrated that veliparib effectively inhibited the colony-forming capacity of medulloblastoma cells, both as a single agent and in combination with irradiation. These data were then validated in vivo using an orthotopic implant model of medulloblastoma. Mice harboring intracranial D425 medulloblastoma xenografts were treated with vehicle, veliparib, 18 Gy multifractionated craniospinal irradiation (CSI), or veliparib combined with 18 Gy CSI. Animals treated with combination therapy exhibited reduced tumor growth rates concomitant with increased intra-tumoral apoptosis observed by immunohistochemistry. Kaplan–Meier analyses revealed a statistically significant increase in survival with combination therapy compared to CSI alone. In summary, PARP inhibition enhanced radiation-induced cytotoxicity of medulloblastoma cells; thus, veliparib or other brain-penetrant PARP inhibitors are potential radiosensitizing agents for the treatment of medulloblastoma.

scholarly journals Cellular response to DNA damage is enhanced by the pR plasmid in mouse cells and in Escherichia coli.

1986 ◽  
Vol 6 (2) ◽  
pp. 586-592 ◽  
Author(s):  
L Marcucci ◽  
F Gigliani ◽  
P A Battaglia ◽  
R Bosi ◽  
E Sporeno ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Statistical Analysis ◽  
Cellular Response ◽  
Regulatory Mechanism ◽  
Uv Light ◽  
Transformed Cells ◽  
Insertion Mutagenesis ◽  
Mouse Cells ◽  
Inducible Repair

The pR plasmid, which enhances the survival of Escherichia coli C600 exposed to UV light by induction of the SOS regulatory mechanism, showed the same effect when it transformed mouse LTA cells (tk-, aprt-). With Tn5 insertion mutagenesis which inactivates UV functions in the pR plasmid, we recognized two different regions of the plasmid, uvp1 and uvp2. These pR UVR- mutants exhibited the same effect in LTA transformed cells, demonstrating that resistance to UV light, carried by the pR plasmid, was really due to the expression of these two regions, which were also in the mouse cells. Statistical analysis showed that the expression of the uvp1 and uvp2 regions significantly increased (P less than 0.01) the survival upon exposure to UV light in mouse cells and bacteria. These results might suggest the presence of an inducible repair response to DNA damage in mouse LTA cells.

Variability in DNA repair and individual susceptibility to genotoxins

1995 ◽  
Vol 41 (12) ◽  
pp. 1848-1853 ◽  
Author(s):  
S A Kyrtopoulos
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Protective Role ◽  
Interindividual Variation ◽  
Human Populations ◽  
Cytostatic Drugs ◽  
Dna Damage And Repair ◽  
Cellular Protection ◽  
Methylated Dna ◽  
Methylating Agents

Abstract DNA repair is an important mechanism of cellular protection from the effects of genotoxic chemicals. Although extensive evidence from studies in experimental systems indicates that variation in DNA repair can significantly influence susceptibility to genotoxins, corresponding studies in human populations are so far limited, mainly because of methodological difficulties. One system, using observations of the accumulation and repair of DNA damage in cancer patients treated with alkylating cytostatic drugs, has provided useful information for assessing the effects of interindividual variation in DNA repair activity on the induction of genotoxic effects in humans. The most detailed studies of this kind have been carried out on patients with cancer (i.e., Hodgkin disease, malignant melanoma) treated with the methylating cytostatic drugs procarbazine or dacarbazine; these studies have provided detailed information on dose-response relationships. They have also demonstrated the protective role of the repair enzyme O6-alkylguanine-DNA alkyltransferase against the accumulation of the premutagenic methylated DNA lesion O6-methylguanine in patients' DNA. Given the strong evidence that exposure of the general population to environmental methylating agents may be extensive, as indicated by the frequent discovery of methylated DNA adducts in human DNA, data on DNA damage and repair in alkylating drug-treated patients and their modulation by host factors may prove useful in efforts to assess the possible carcinogenic risks posed by exposure to environmental methylating agents.

scholarly journals Mutational signatures are jointly shaped by DNA damage and repair

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nadezda V. Volkova ◽  
Bettina Meier ◽  
Víctor González-Huici ◽  
Simone Bertolini ◽  
Santiago Gonzalez ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Excision Repair ◽  
Point Mutations ◽  
Mutational Signatures ◽  
Dna Damage And Repair ◽  
C Elegans ◽  
Dna Repair Deficiency ◽  
Dna Alterations ◽  
Repair Pathways

AbstractCells possess an armamentarium of DNA repair pathways to counter DNA damage and prevent mutation. Here we use C. elegans whole genome sequencing to systematically quantify the contributions of these factors to mutational signatures. We analyse 2,717 genomes from wild-type and 53 DNA repair defective backgrounds, exposed to 11 genotoxins, including UV-B and ionizing radiation, alkylating compounds, aristolochic acid, aflatoxin B1, and cisplatin. Combined genotoxic exposure and DNA repair deficiency alters mutation rates or signatures in 41% of experiments, revealing how different DNA alterations induced by the same genotoxin are mended by separate repair pathways. Error-prone translesion synthesis causes the majority of genotoxin-induced base substitutions, but averts larger deletions. Nucleotide excision repair prevents up to 99% of point mutations, almost uniformly across the mutation spectrum. Our data show that mutational signatures are joint products of DNA damage and repair and suggest that multiple factors underlie signatures observed in cancer genomes.

scholarly journals DNA Repair Biosensor-Identified DNA Damage Activities of Endophyte Extracts from Garcinia cowa

Biomolecules ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1680
Author(s):  
Tassanee Lerksuthirat ◽  
Rakkreat Wikiniyadhanee ◽  
Sermsiri Chitphuk ◽  
Wasana Stitchantrakul ◽  
Somponnat Sampattavanich ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Fluorescent Proteins ◽  
Strand Break ◽  
Control Group ◽  
Focus Formation ◽  
Dna Damage And Repair ◽  
Biological Compounds ◽  
Repair Pathways ◽  
Garcinia Cowa

Recent developments in chemotherapy focus on target-specific mechanisms, which occur only in cancer cells and minimize the effects on normal cells. DNA damage and repair pathways are a promising target in the treatment of cancer. In order to identify novel compounds targeting DNA repair pathways, two key proteins, 53BP1 and RAD54L, were tagged with fluorescent proteins as indicators for two major double strand break (DSB) repair pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). The engineered biosensor cells exhibited the same DNA repair properties as the wild type. The biosensor cells were further used to investigate the DNA repair activities of natural biological compounds. An extract from Phyllosticta sp., the endophyte isolated from the medicinal plant Garcinia cowa Roxb. ex Choisy, was tested. The results showed that the crude extract induced DSB, as demonstrated by the increase in the DNA DSB marker γH2AX. The damaged DNA appeared to be repaired through NHEJ, as the 53BP1 focus formation in the treated fraction was higher than in the control group. In conclusion, DNA repair-based biosensors are useful for the preliminary screening of crude extracts and biological compounds for the identification of potential targeted therapeutic drugs.

Involvement of Death-Associated Protein Kinases In DNA Damage Responses of B-ALL Cells.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3369-3369
Author(s):  
Magali Humbert ◽  
Michaela Medova ◽  
Barbara Geering ◽  
Wieslawa Blank-Liss ◽  
Hans-Uwe Simon ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Gamma Irradiation ◽  
Protein Kinases ◽  
Dna Damage Response ◽  
Lymphoblastic Leukemia ◽  
Damage Response ◽  
Dna Damage Responses

Abstract Abstract 3369 Intact DNA damage response pathways are important for genomic fidelity of cells in order to avoid tumor formation. On the other hand, inhibition of DNA repair provides an important mechanism to enhance the therapeutic efficacy of DNA damaging agents such as gamma-irradiation. Thus, it is important to identify novel players in DNA damage response that might represent novel targets for combination therapies. Death-associated protein kinases (DAPK) are serine/threonine kinases believed to be involved in cell death and autophagy mechanisms, whereby particularly the role of DAPK1 has previously been investigated. The DAPK family is composed of five members: DAPK1, DAPK2 (or DRP-1), DAPK3 (or ZIP kinase), DRAK1 and DRAK2. DAPK1 and DAPK2 share 80% homology in the catalytic domain. Generally, the role of DAPK in DNA damage responses is not well studied. To analyze the role of DAPK1 and DAPK2 in response to gamma-irradiation, we used p53 wild-type REH B-cell acute lymphoblastic leukemia (B-ALL) cells as a model. In response to irradiation, DAPK1 protein expression increased paralleled by an increased of total p53, phospho-Ser20-p53 and p21WAF1/CIP1. DAPK2 expression, however, did not increase. Since upregulation of p21WAF1/CIP1, a classical p53 target in response to DNA damage leads to cell cycle arrest, we asked whether knocking down DAPK1 or DAPK2 might affect the cell cycle. Interestingly, knocking down DAPK2 but not DAPK1 led to a significant increase of S-phase cells upon irradiation. Moreover, knocking down DAPK2 attenuated the induction of DAPK1 upon irradiation indicating a DAPK2-DAPK1 cascade in DNA damage responses. Next, given the significant role of p21WAF1/CIP1 and p53 in DNA damage responses, we tested if DAPK2 might directly participate in a novel signaling pathway by interacting with these proteins. Indeed, pull down assays revealed that p21WAF1/CIP1 and p53 are novel DAPK2 interacting proteins. Clearly, further experiments are needed to define the DAPK2-DAPK1-p53- p21WAF1/CIP1 network in DNA repair pathways. In conclusion, we identified a novel role for DAPK1 and DAPK2 in DNA damage responses of B-ALL cells and propose a novel DAPK2/DAPK1/p53/ p21WAF1/CIP1 DNA damage regulatory pathway. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Recent Physical Activity in Relation to DNA Damage and Repair Using the Comet Assay

2014 ◽  
Vol 11 (4) ◽  
pp. 770-776 ◽  
Author(s):  
Stephanie Whisnant Cash ◽  
Shirley A.A. Beresford ◽  
Thomas L. Vaughan ◽  
Patrick J. Heagerty ◽  
Leslie Bernstein ◽  
...  
Keyword(s):  
Physical Activity ◽  
Dna Damage ◽  
Dna Repair ◽  
Comet Assay ◽  
High Intensity ◽  
Total Activity ◽  
Washington State ◽  
Dna Damage And Repair ◽  
Activity Intensity ◽  
Very High

Background:Limited evidence suggests that very high-intensity exercise is positively associated with DNA damage but moderate exercise may be associated with DNA repair.Methods:Participants were 220 healthy, Washington State 50- to 76-year-olds in the validity/biomarker substudy of the VITamins And Lifestyle (VITAL) cohort, who provided blood samples and completed questionnaires assessing recent physical activity and demographic and health factors. Measures included nested activity subsets: total activity, moderate- plus high-intensity activity, and high-intensity activity. DNA damage (n = 122) and repair (n = 99) were measured using the comet assay. Multivariate linear regression was used to estimate regression coefficients and associated 95% confidence intervals (CIs) for relationships between MET-hours per week of activity and each DNA outcome (damage, and 15- and 60-minute repair capacities).Results:DNA damage was not associated with any measure of activity. However, 60-minute DNA repair was positively associated with both total activity (β = 0.21, 95% CI: 0.0057–0.412; P = .044) and high-intensity activity (β = 0.31, 95% CI: 0.20–0.60; P = .036), adjusting for age, sex, BMI, and current multivitamin use.Conclusions:This study is the first to assess broad ranges of activity intensity levels related to DNA damage and repair. Physical activity was unrelated to DNA damage but was associated with increased repair.

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