scholarly journals A DNA Damage-Repair Dynamic Model for HRS/IRR Effects of C.elegans Induced by Neutron Irradiation

Dose-Response ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 155932582110012
Author(s):  
Guangyan Feng ◽  
Lianxin Zhang ◽  
Zhanguo Yang ◽  
Yong Zhang ◽  
Siwei Zhang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Neutron Irradiation ◽  
Low Dose ◽  
Biological Effects ◽  
Dna Damage Repair ◽  
Experimental Results ◽  
Dependent Manner ◽  
Survival Fraction ◽  
C Elegans ◽  
Damage Repair

Neutron irradiation which could trigger severe biological effects, is being applied in nuclear plants, radiotherapy, and aerospace gradually. Low dose hyper-radiosensitivity response of low Linear Energy Transfer (LET) irradiation on the cell survival has become a matter of great interest since its discovery, but a few research have been done on this response induced by neutron irradiation. To investigate this response induced by neutron irradiation, Caenorhabditis elegans ( C. elegans) was irradiated by neutron irradiation. The surviving fraction of C. elegans on the 12th day after irradiation was analyzed, which showed a hyper-radiosensitive response at low doses and followed by an increase in survival fraction at slightly higher doses. The finding of this work that neutron irradiation decreased the surviving fraction in a non-dose-dependent manner was different from previous low-LET irradiation studies. To understand the experimental results, a DNA damage-repair model was introduced. By comparing experimental results with theoretical analyses, we suggest that the low dose hyper-radiosensitivity response of neutron irradiation may possible related to different radiation types and DNA damage recognition proteins and immune system of C. elegans.

Abstract PR01: EMSY impairs DNA damage repair in a phosphorylation-dependent manner.

2016 ◽  
Author(s):  
Petar Jelinic ◽  
Laura Eccles ◽  
Simon N. Powell ◽  
Douglas A. Levine
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Dependent Manner ◽  
Damage Repair

Bortezomib Enhances Melphalan Response by Altering Fanconi Anemia (FA)/BRCA Pathway Expression and Function.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 840-840 ◽  
Author(s):  
Danielle N. Yarde ◽  
Lori A. Hazlehurst ◽  
Vasco A. Oliveira ◽  
Qing Chen ◽  
William S. Dalton
Keyword(s):  
Gene Expression ◽  
Dna Damage ◽  
Dna Repair ◽  
Low Dose ◽  
Dna Damage Repair ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Multiple Myeloma Cell ◽  
Damage Repair ◽  
Pre Treatment

Abstract The FA/BRCA pathway is involved in DNA damage repair and its importance in oncogenesis has only recently been implicated. Briefly, 8 FA/BRCA pathway family members facilitate the monoubiquitination of FANCD2. Upon monoubiquitination, FANCD2 translocates to the DNA repair foci where it interacts with other proteins to initiate DNA repair. Previously, we reported that the FA/BRCA pathway is upregulated in multiple myeloma cell lines selected for resistance to melphalan (Chen, et al, Blood 2005). Further, reducing FANCF in the melphalan resistant 8226/LR5 myeloma cell line partially reversed resistance, whereas overexpressing FANCF in the drug sensitive 8226/S myeloma line conferred resistance to melphalan. Others have reported, and we have also verified, that bortezomib enhances melphalan response in myeloma cells; however, the mechanism of enhanced melphalan activity in combination with bortezomib has not been reported. Based on our observation that the FA/BRCA pathway confers melphalan resistance, we hypothesized that bortezomib enhances melphalan response by targeting FA/BRCA DNA damage repair pathway genes. To investigate this hypothesis, we first analyzed FA/BRCA gene expression in 8226/S and 8226/LR5 cells treated with bortezomib, using a customized microfluidic card (to detect BRCA1, BRCA2, FANCA, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCL, RAD51 and RAD51C) and q-PCR. Interestingly, we found that low dose (5nM) bortezomib decreased many FA/BRCA pathway genes as early as 2 hours, with maximal decreases seen at 24 hours. Specifically, 1.5- to 2.5-fold decreases in FANCA, FANCC, FANCD2, FANCE and RAD51C were seen 24 hours post bortezomib exposure. Moreover, pre-treatment of myeloma cells with low dose bortezomib followed by melphalan treatment revealed a greater than 2-fold reduction in FANCD2 gene expression levels. We also found that melphalan treatment alone enhanced FANCD2 protein expression and activation (monoubiquitination), whereas the combination treatment of bortezomib followed by melphalan decreased activation and overall expression of FANCD2 protein. Taken together, these results suggest that bortezomib enhances melphalan response in myeloma by targeting the FA/BRCA pathway. Further understanding of the role of the FA/BRCA pathway in determining melphalan response may allow for more customized and effective treatment of myeloma.

Effect of enzalutamide on sensitivity in prostate cancer cells to radiation by inhibition of DNA double strand break repair.

2017 ◽  
Vol 35 (6_suppl) ◽  
pp. 208-208 ◽  
Author(s):  
Maryam Ghashghaei ◽  
Thierry Muanza ◽  
Miltiadis Paliouras ◽  
Tamim Niazi
Keyword(s):  
Prostate Cancer ◽  
Dna Damage ◽  
Dna Damage Repair ◽  
Strand Break ◽  
Dependent Manner ◽  
Castration Resistance ◽  
Concurrent Administration ◽  
Damage Repair ◽  
Pathway Inhibition ◽  
Approved Drugs

208 Background: Prostate cancer is the second leading cause of cancer-related deaths amongst men in North America. Data suggests that, following radiation therapy (XRT), androgen receptor (AR) enhances DNA damage repair and contributes to resistance of prostate cancer (PCa) cells to XRT. At present AR-pathway inhibition is the mainstay treatment of metastatic castration resistance prostate cancer (mCRPC). Enzalutamide (ENZA), a potent AR inhibitor is one of the approved drugs in this setting. The purpose of this study was to assess the potential radiosensitization of ENZA and its mechanism of action in hormone resistant PCa cells. Methods: The effect of ENZA alone or in combination with XRT was assessed on hormone-sensitive, (HS: LNCaP, PC3-T877A) and insensitive PCa cells (HI: PC3, PC3-AR V7, C4-2) using viability and clonogenic assays, cell cycle arrest and DNA damage analysis. Results: MTT assay demonstrates that ENZA significantly inhibits the proliferation of HS PCa cells in a dose dependent manner whereas CRPC required ENZA in combination with ADT (androgen deprivation therapy). Additionally, clonogenic assay proves that concurrent administration of ENZA or ADT+ENZA and XRT led to a supra-additive antitumor effect with the dose enhancement factor of 1.76±0.008 in LNCaP, 1.65±0.01 in PC3-T877A and 1.35±0.003 in C4-2 respectively at surviving fraction of 0.1. This effect was not observed in PC3 and PC3-AR V7 cells pre-treated with ENZA (in all cases DEF = 1 at SF = 0.1). Additionally, the level of γH2AX increased in HS cells and CRPC cells treated with ENZA/ADT+ENZA and XRT when compared to XRT alone. The enhanced H2AX activity remained unchanged up to 24 hours after combination treatment. Furthermore, there is an initial inhibition of DNA-PKcs in HS and CRPC cells treated with ENZA/ADT+ENZA administered before XRT. Conclusions: Our data suggest that the higher efficacy of ENZA/ENZA+ADT and XRT could be partially due to inhibition of DNA damage repair. Our results demonstrated a significant enhancement of XRT efficacy and confirms the rational for the ongoing combination clinical trials with XRT.

scholarly journals Inhibition of ATR-Chk1 signaling blocks DNA double-strand-break repair and induces cytoplasmic vacuolization in metastatic osteosarcoma

2020 ◽  
Vol 12 ◽  
pp. 175883592095690 ◽  
Author(s):  
Xiaoyang Li ◽  
Dylan C. Dean ◽  
Gregory M. Cote ◽  
Lee Zou ◽  
Francis J. Hornicek ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Dna Damage ◽  
Therapeutic Target ◽  
Ex Vivo ◽  
Dna Damage Repair ◽  
Parp Cleavage ◽  
Dependent Manner ◽  
Cytoplasmic Vacuolization ◽  
Damage Repair ◽  
Metastatic Osteosarcoma

Background: Ataxia-telangiectasia and Rad3 related protein kinase (ATR) is an essential regulator of the DNA damage response in various cancers; however, its expression and roles in osteosarcoma are unclear. We therefore chose to evaluate the significance and mechanism of ATR in metastatic osteosarcoma, as well as its potential to be a therapeutic target. Methods: The osteosarcoma tissue microarrays constructed from 70 patient specimens underwent immunohistochemistry to quantify ATR and activated phospho-ATR (pATR) expression and their correlation with clinical outcomes. ATR sublocalization within the metastatic osteosarcoma cells was confirmed by immunofluorescence assay. Cell proliferation, apoptosis, and migration were evaluated following treatment with ATR siRNA or the selective inhibitor Berzosertib. Antitumor effects were determined with ex vivo three-dimensional (3D) culture models, and the impacts on the DNA damage repair pathways were measured with Western blotting. Results: Elevated ATR and activated pATR expression correlated with shorter patient survival and less necrosis following neoadjuvant chemotherapy. Intranuclear sublocalization of ATR and pATR suggested a mechanism related to DNA replication. ATR knockdown with siRNA or inhibition with Berzosertib suppressed cell proliferation in a time- and dose-dependent manner and induced apoptosis. In addition, ATR inhibition decreased Chk1 phosphorylation while increasing γH2AX expression and PARP cleavage, consistent with the interference of DNA damage repair. The ATR inhibitor Berzosertib also produced the characteristic cytoplasmic vacuolization preceding cell death, and suppressed ex vivo 3D spheroid formation and cell motility. Conclusion: The faithful dependence of cells on ATR signaling for survival and progression makes it an emerging therapeutic target in metastatic osteosarcoma.

scholarly journals A network of nuclear envelope proteins and cytoskeletal force generators mediates movements of and within nuclei throughout Caenorhabditis elegans development

2019 ◽  
Vol 244 (15) ◽  
pp. 1323-1332 ◽  
Author(s):  
Daniel A Starr
Keyword(s):  
Dna Damage ◽  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Dna Damage Repair ◽  
Nuclear Migration ◽  
Envelope Proteins ◽  
Nuclear Positioning ◽  
C Elegans ◽  
Damage Repair

Nuclear migration and anchorage, together referred to as nuclear positioning, are central to many cellular and developmental events. Nuclear positioning is mediated by a conserved network of nuclear envelope proteins that interacts with force generators in the cytoskeleton. At the heart of this network are linker of nucleoskeleton and cytoskeleton (LINC) complexes made of Sad1 and UNC-84 (SUN) proteins at the inner nuclear membrane and Klarsicht, ANC-1, and Syne homology (KASH) proteins in the outer nuclear membrane. LINC complexes span the nuclear envelope, maintain nuclear envelope architecture, designate the surface of nuclei distinctly from the contiguous endoplasmic reticulum, and were instrumental in the early evolution of eukaryotes. LINC complexes interact with lamins in the nucleus and with various cytoplasmic KASH effectors from the surface of nuclei. These effectors regulate the cytoskeleton, leading to a variety of cellular outputs including pronuclear migration, nuclear migration through constricted spaces, nuclear anchorage, centrosome attachment to nuclei, meiotic chromosome movements, and DNA damage repair. How LINC complexes are regulated and how they function are reviewed here. The focus is on recent studies elucidating the best-understood network of LINC complexes, those used throughout Caenorhabditis elegans development. Impact statement Defects in nuclear positioning disrupt development in many mammalian tissues. In human development, LINC complexes play important cellular functions including nuclear positioning, homolog pairing in meiosis, DNA damage repair, wound healing, and gonadogenesis. The topics reviewed here are relevant to public health because defects in nuclear positioning and mutations in LINC components are associated with a wide variety of human diseases including muscular dystrophies, neurological disorders, progeria, aneurysms, hearing loss, blindness, sterility, and multiple cancers. Although this review focuses on findings in the model nematode Caenorhabditis elegans, the studies are relevant because almost all the findings originally made in C. elegans are conserved to humans. Furthermore, C. elegans remains the best described network for how LINC complexes are regulated and function.

scholarly journals Mitotic Errors Promote Genomic Instability and Leukemia in a Novel Mouse Model of Fanconi Anemia

2021 ◽  
Vol 11 ◽  
Author(s):  
Donna M. Edwards ◽  
Dana K. Mitchell ◽  
Zahi Abdul-Sater ◽  
Ka-Kui Chan ◽  
Zejin Sun ◽  
...  
Keyword(s):  
Dna Damage ◽  
Genomic Instability ◽  
Fanconi Anemia ◽  
Spindle Assembly Checkpoint ◽  
Dna Damage Repair ◽  
Spindle Assembly ◽  
Dependent Manner ◽  
Damage Repair

Fanconi anemia (FA) is a disease of genomic instability and cancer. In addition to DNA damage repair, FA pathway proteins are now known to be critical for maintaining faithful chromosome segregation during mitosis. While impaired DNA damage repair has been studied extensively in FA-associated carcinogenesis in vivo, the oncogenic contribution of mitotic abnormalities secondary to FA pathway deficiency remains incompletely understood. To examine the role of mitotic dysregulation in FA pathway deficient malignancies, we genetically exacerbated the baseline mitotic defect in Fancc-/- mice by introducing heterozygosity of the key spindle assembly checkpoint regulator Mad2. Fancc-/-;Mad2+/- mice were viable, but died from acute myeloid leukemia (AML), thus recapitulating the high risk of myeloid malignancies in FA patients better than Fancc-/-mice. We utilized hematopoietic stem cell transplantation to propagate Fancc-/-; Mad2+/- AML in irradiated healthy mice to model FANCC-deficient AMLs arising in the non-FA population. Compared to cells from Fancc-/- mice, those from Fancc-/-;Mad2+/- mice demonstrated an increase in mitotic errors but equivalent DNA cross-linker hypersensitivity, indicating that the cancer phenotype of Fancc-/-;Mad2+/- mice results from error-prone cell division and not exacerbation of the DNA damage repair defect. We found that FANCC enhances targeting of endogenous MAD2 to prometaphase kinetochores, suggesting a mechanism for how FANCC-dependent regulation of the spindle assembly checkpoint prevents chromosome mis-segregation. Whole-exome sequencing revealed similarities between human FA-associated myelodysplastic syndrome (MDS)/AML and the AML that developed in Fancc-/-; Mad2+/- mice. Together, these data illuminate the role of mitotic dysregulation in FA-pathway deficient malignancies in vivo, show how FANCC adjusts the spindle assembly checkpoint rheostat by regulating MAD2 kinetochore targeting in cell cycle-dependent manner, and establish two new mouse models for preclinical studies of AML.

scholarly journals DNA Damage Repair Interference By WEE1 Inhibition with AZD1775 Overcomes Combined Azacitidine and Venetoclax Resistance in Acute Myeloid Leukmeia (AML)

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2559-2559
Author(s):  
Raoul Tibes ◽  
Diego Ferreira Coutinho ◽  
Michael Tuen Tuen ◽  
Xufeng Chen ◽  
Christina Glytsou ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Lines ◽  
Molecular Mechanisms ◽  
Low Dose ◽  
Dna Damage Repair ◽  
Single Agent ◽  
Leukemic Cells ◽  
Damage Repair ◽  
Arac Treatment ◽  
Acute Myeloid

Acute myeloid leukemia (AML) has remained one of the most treatment resistant and deadliest cancers. The survival of AML blast cells is controlled by the balance of anti- and pro-apoptotic proteins. Recently approved Bcl-2 targeted therapy of AML with the Bcl-2 specific inhibitor Venetoclax in combinations has improved patients outcomes. However, a priori and developing resistance to venetoclax combinations with hypomethylating agents (HMA) azacitidine and decitabine challenge this treatment. As such, novel therapies to overcome venetoclax-HMA resistance are urgently needed. We have identified a combination of DNA damage repair interference by WEE1 inhibition with AZD1775, combined with low dose cytarabine (AraC) as an effective strategy to overcome combined venetoclax-azacitidine resistance (VAR). AZD1775 with low dose AraC induced massive apoptosis (by Annexin V and cleaved caspase-3) and almost completely reduced viability and clonogenic growth of primary AML cells. To delineate the molecular mechanism of the synergistic effect of AZD1775/AraC we performed RNAseq analysis of single agent or the combination of AZD1775+AraC in AML cell lines and primary CD34+ selected AML patient cells with the goal to identify deferentially regulated genes indicating a mechanistic underpinning of the potent activity. Only 2 genes were deferentially regulated across cell lines and CD34+ selected cells under AZD1775+AraC treatment: one of these is NR4A1, an orphan nuclear receptor, which we went on to validate as a potential downstream target of Wee1 inhibition. The inactivation of NR4A1 in mice was previously shown to induce AML and to maintain leukemia stem cells. Using qPCR we confirmed that the expression of NR4A1 is upregulated after AZD1775/AraC combo treatment in human leukemic cells. We then demonstrated that activators of NR4A1 (cytosporone B and pPhOCH3) reduce viability of leukemic cells, while NR4A1 inhibitor pPhOH was able to abolish the effect of AZD1775/AraC combo treatment increasing leukemic cell viability]. To investigate the involvement of mitochondria in the effect of AZD1775/AraC treatment we performed the expression of mitochondrial genes and pathway analyses in RNAseq data and found that mitochondrial gene expression, including many genes involved in apoptosis, has most dramatic changes in the combo treatment if compared to the single agents. Subsequently, we have examined the expression of the main BCL-2 family apoptotic genes by qPCR and western blot analysis. We found that AZD1775/AraC induces the expression of Bim isoforms, whereas Bcl-2, Mcl-1 and Bcl-Xl were largely unaffected. NR4A1 was previously shown to translocate to mitochondria, release Bim from Bcl-2 protein binding, as well as convert Bcl-2 to an extreme potent pro-apoptotic form. Finally, we generated several additional VAR cell lines and cells with subclones and demonstrated that AZD1775/AraC combination treatment is able to overcome VAR in almost every clone. Our results show that DNA damage repair interference with Wee1 inhibition has the potential to overcome VAR through a novel mechanisms of AZD1775 increasing NR4A1, freeing pro-apoptotic Bim irrespective of anti-apoptotic Bcl-2 proteins leading to massive apoptotic cell death in AML cells. The precise molecular mechanisms and the involvement of NR4A1 in this phenomenon will be presented at the meeting. Our findings will help to develop new therapeutic strategies in AML treatment and a trial of AZD1775 + AraC in AML is currently ongoing. Disclosures No relevant conflicts of interest to declare.

Enhancement of UVB-induced DNA damage repair after a chronic low-dose UVB pre-stimulation

DNA Repair ◽  
2018 ◽  
Vol 63 ◽  
pp. 56-62 ◽  
Author(s):  
Marie-Catherine Drigeard Desgarnier ◽  
Patrick J. Rochette
Keyword(s):  
Dna Damage ◽  
Low Dose ◽  
Dna Damage Repair ◽  
Damage Repair
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