Reduced DNA double strand breaks in chlorambucil resistant cells are related to high DNA-PKcs activity and low oxidative stress

Toxicology ◽  
2003 ◽  
Vol 193 (1-2) ◽  
pp. 137-152 ◽  
Author(s):  
Istvan Boldogh ◽  
Gargi Roy ◽  
Myung-Soog Lee ◽  
Attila Bacsi ◽  
Tapas K Hazra ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Resistant Cells

Cobalt and nickel impair DNA metabolism by the oxidative stress independent pathway

Metallomics ◽  
2017 ◽  
Vol 9 (11) ◽  
pp. 1596-1609 ◽  
Author(s):  
Vineet Kumar ◽  
Rajesh Kumar Mishra ◽  
Gursharan Kaur ◽  
Dipak Dutta
Keyword(s):  
Oxidative Stress ◽  
Metal Ions ◽  
Replication Fork ◽  
Double Strand Breaks ◽  
Dna Metabolism ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Replication Fork Progression ◽  
Nickel Exposure ◽  
Cobalt And Nickel

Cobalt and nickel exposure leads to DNA double-strand breaks, decelerating replication fork progression. In parallel, the metal ions inhibit RecBCD function to block SOS-mediated repair of the damaged DNA.

The Oncogene MYC Triggers Replicative Stress and DNA Damage In Multiple Myeloma

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3114-3114
Author(s):  
Francesca Cottini ◽  
Teru Hideshima ◽  
Giovanni Tonon ◽  
Kenneth C. Anderson
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Dna Replication ◽  
Plasma Cells ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Replicative Stress ◽  
Stress Markers ◽  
Dna Replication Stress

Abstract Multiple myeloma (MM) is a clonal proliferation of malignant plasma cells, carrying abnormal karyotypes, chromosomal translocations, and innumerous DNA copy-number variations. We and others have previously shown that MM cells have constitutive DNA damage and DNA damage response (DDR), while normal plasma cells (NPCs) are negative for these DDR markers. Moreover, we recently observed that markers of replicative stress, such as p-ATR and p-CHK1 together with RPA foci, are also present in MM cells. The MYC (or c-MYC) oncogene is pervasively altered in MM. Since MYC is associated with DNA replication stress, oxidative stress, and DDR, we explored whether MYC is implicated in these pathways in MM. Indeed, by analyzing various DNA damage gene expression signatures, we found a positive correlation between MYC levels and ongoing DNA damage. We next examined whether MYC modulation could alter replicative stress markers, and induce DNA double-strand breaks. In a gain-of-function model, c-MYC was expressed in U266 MM cell line, which has low c-MYC levels and importantly shows low levels of ongoing DNA damage. In parallel, the H929 and MM.1S MM cell lines were used to knock-down c-MYC expression. Re-expression of a functional MYC-EGFP in U266 cells induced replicative stress markers, such as RAD51, RPA, and phospho-CHK1 foci, as well as increased RAD51, RPA and phospho-CHK1 protein levels. To determine whether this phenotype was linked to concomitant oxidative stress, we incubated MM cells with an antioxidant reagent N-Acetylcysteine (NAC). We observed a modest reduction in replicative markers after NAC treatment, which was more evident by MYC overexpression. Taken together, these results suggest that the replicative stress induced by MYC is, at least in part, associated with oxidative stress. Additionally, MYC-EGFP positive U266 cells also show DNA damage, evidenced by appearance of phospho-H2A.X foci (which detect DNA double strand breaks), that in turn triggers an intense DNA damage response, assessed by phospho-ATM/phospho CHK2 positivity. In contrast, all these DDR markers were downregulated by MYC silencing, prior to cell death, in MM.1S and H929 MM cell lines. Finally, we examined whether targeting the replicative stress response may represent a novel therapeutic strategy in MM cells with high expression of MYC. Specifically, we treated U266 cells transduced with MYC or control LACZ cells, as well as MM.1S and H929 transfected with a specific MYC-shRNA or their scrambled shRNA controls, with a small molecule ATR inhibitor VE-821 which prevents proper DNA repair after DNA damage. Cells overexpressing MYC were significantly more sensitive to VE-821 treatment compared to controls; conversely MYC-silenced cells were more resistant to VE-821. These results suggest the potential utility of VE-821 as a novel therapeutic agent in cells with high expression of MYC. In conclusion, our data show that MYC may exert its oncogenic activity partly through its ability to trigger DNA replication stress, leading to DNA damage and genomic instability in MM cells. Given the pervasive deregulation of MYC present in MM cells, its role in DNA replication and DNA damage may correlate with the extensive genomic rearrangements observed in MM cells. Therefore, treatment strategies targeting this Achilles' heel may improve patient outcome in MM. Disclosures: Hideshima: Acetylon Pharmaceuticals: Consultancy. Anderson:Acetylon, Oncopep: Scientific Founder, Scientific Founder Other; Celgene, Millennium, BMS, Onyx: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Role of Interleukin33 in Rejuvenation of Aged Neurons and Age-Related Dementias

2021 ◽  
Vol 16 ◽  
pp. 263310552110302
Author(s):  
Yahuan Lou
Keyword(s):  
Oxidative Stress ◽  
Potential Risk ◽  
Middle Age ◽  
Late Onset ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Age Related ◽  
Deficient Mice

Late-onset Alzheimer’s disease (LOAD) is the most common age-related dementia, and its etiology remains unclear. Recent studies have linked abnormal neuronal aging to LOAD. Neurons are non-proliferative, and thus, majority of aged neurons must be rejuvenated through repairing or eliminating damaged molecules to regain their healthy status and functionalities. We discovered a surge of oxidative stress in neurons at middle age in mice. A rapid upregulation of neuronal rejuvenation is vital, while astrocyte-expressed interleukin33 (IL33), an IL1-like cytokine, is critical for this process. Thus, IL33-deficiency cripples the neuronal rejuvenation mechanisms, such as repairing DNA double strand breaks, eliminating damaged molecules by autophagy or by glymphatic drainage. IL33-deficient mice develop tau deposition and age-related dementia following a path similar to LOAD. We hypothesize that any interferences on IL33-initiated rejuvenation process for aged neurons after middle life is a potential risk for LOAD development.

Abstract P321: Oxidative Stress Induces DNA Double-Strand Breaks and Activates DNA Damage Responses in Vascular Smooth Muscle Cells: A Possible Mechanism for Atherosclerosis Progression

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Takafumi Ishida ◽  
Mari Ishida ◽  
Satoshi Tashiro ◽  
Chiemi Sakai ◽  
Hitomi Uchida ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Dna Damage Responses

Backgrounds: Oxidative stress is thought to be a pathogenic mediator of atherosclerosis. Oxidative stress induces DNA damage, and the unrepaired or improperly repaired DNA damage increases genomic instability, which cause cell death, senescence, or dysregulation of cellular functions. Pathogenesis of both Hutchinson-Gilford Progeria syndrome and Werner syndrome, which feature prominent atherosclerotic disease at young age, involves impaired DNA repair and the resultant genomic instability. The purpose of this study is to determine whether oxidative stress causes DNA damage in vascular smooth muscle cells (VSMC) and to elucidate the role of DNA damage responses in atherosclerosis and the fate of VSMC. Methods and Results: Immunoreactivity against gamma-H2AX, a sensitive marker for DNA double-strand breaks (DSBs), which is the most severe form of DNA damage, was increased in human atherosclerotic plaques, but not in the adjacent normal areas. gamma-H2AX staining was observed in almost same regions where 8-oxo-dG immunoreactivity, an oxidative modification of DNA, was observed. Apoptotic cells were abundant in atherosclerotic lesions, but not in normal areas. In cultured human aortic smooth muscle cells (HASM), 15 min incubation with H2O2 (100 microM) induced foci formation of gamma-H2AX in the nuclei. H2O2 activated various signaling molecules involved in DNA damage responses, including ATM, Chk2, DNA-PK and p53 in HASM. Some H2O2-induced DSBs persisted after 24 hours, at which point apoptosis was induced in 7.1 ± 1.3 % of HASM, as detected by TUNEL method. Knockdown experiments using siRNA revealed that ATM-, DNA-PK-, or Chk2-deficient VSMC were more resistant to H2O2-induced apoptosis. Conclusions: In summary, 1) DNA double-strand breaks were accumulated in human atherosclerotic plaques, 2) oxidative stress induced double-strand breaks and activation of DNA damage response in vascular smooth muscle cells, and 3) impairment of DNA damage responses modulated damage-induced cell fate such as apoptosis. Thus, DNA damage itself or alteration in DNA damage responses may be involved in the mechanisms for progression of atherosclerosis.

scholarly journals SUMO proteins are involved in the stress response during spermatogenesis and are localized to DNA double-strand breaks in germ cells

Reproduction ◽  
2010 ◽  
Vol 139 (6) ◽  
pp. 999-1010 ◽  
Author(s):  
Vibha Shrivastava ◽  
Marina Pekar ◽  
Eliana Grosser ◽  
Jay Im ◽  
Margarita Vigodner
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Germ Cells ◽  
Stress Responses ◽  
Double Strand Breaks ◽  
Cellular Stress Response ◽  
Short Exposure ◽  
Dna Double Strand Breaks ◽  
Strand Breaks

Small ubiquitin-like modifiers (SUMO) proteins have been implicated in cellular stress response in different tissues, but whether sumoylation has a similar role during spermatogenesis is currently unknown. In this study, changes in the levels of both free SUMO isoforms and high-molecular weight (HMW) SUMO conjugates were monitored before and after the induction of different types of cellular stresses. Using cell lines and primary cells freshly isolated from mouse testes, significant changes were detected in the levels of SUMO1 and SUMO2/3 conjugates following short exposure of the cells to heat stress and oxidative stress. While high concentrations of H2O2caused an increase in protein sumoylation, low concentrations of H2O2mostly caused protein desumoylation. Immunofluorescence studies localized SUMO to the sites of DNA double-strand breaks in stressed germ cells and during meiotic recombination. To study the effect of oxidative stressin vivo, animals exposed to tobacco smoke for 12 weeks were used. Changes in sumoylation of HMW proteins were consistent with their oxidative damage in the tobacco-exposed mice. Our results are consistent with the important roles of different SUMO isoforms in stress responses in germ cells. Furthermore, this study identified topoisomerase 2 α as one of the targets of sumoylation during normal spermatogenesis and under stress.

Repair pathway choice for double-strand breaks

2020 ◽  
Vol 64 (5) ◽  
pp. 765-777 ◽  
Author(s):  
Yixi Xu ◽  
Dongyi Xu
Keyword(s):  
Cell Cycle ◽  
Double Strand Breaks ◽  
Homologous Region ◽  
Gene Repair ◽  
Repair Pathway ◽  
Dna Double Strand Breaks ◽  
Environmental Radiation ◽  
Strand Breaks ◽  
Dna End Resection ◽  
End Resection

Abstract Deoxyribonucleic acid (DNA) is at a constant risk of damage from endogenous substances, environmental radiation, and chemical stressors. DNA double-strand breaks (DSBs) pose a significant threat to genomic integrity and cell survival. There are two major pathways for DSB repair: nonhomologous end-joining (NHEJ) and homologous recombination (HR). The extent of DNA end resection, which determines the length of the 3′ single-stranded DNA (ssDNA) overhang, is the primary factor that determines whether repair is carried out via NHEJ or HR. NHEJ, which does not require a 3′ ssDNA tail, occurs throughout the cell cycle. 53BP1 and the cofactors PTIP or RIF1-shieldin protect the broken DNA end, inhibit long-range end resection and thus promote NHEJ. In contrast, HR mainly occurs during the S/G2 phase and requires DNA end processing to create a 3′ tail that can invade a homologous region, ensuring faithful gene repair. BRCA1 and the cofactors CtIP, EXO1, BLM/DNA2, and the MRE11–RAD50–NBS1 (MRN) complex promote DNA end resection and thus HR. DNA resection is influenced by the cell cycle, the chromatin environment, and the complexity of the DNA end break. Herein, we summarize the key factors involved in repair pathway selection for DSBs and discuss recent related publications.

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