Drug-induced DNA damage and tumor chemosensitivity.

1990 ◽  
Vol 8 (12) ◽  
pp. 2062-2084 ◽  
Author(s):  
R J Epstein
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Tumor Cell ◽  
Malignant Disease ◽  
Dna Lesions ◽  
Drug Induced ◽  
Cell Subpopulations ◽  
Therapeutic Cell

Cytotoxic drugs act principally by damaging tumor-cell DNA. Quantitative analysis of this interaction provides a basis for understanding the biology of therapeutic cell kill as well as a rational strategy for optimizing and predicting tumor response. Recent advances have made it possible to correlate assayed DNA lesions with cytotoxicity in tumor cell lines, in animal models, and in patients with malignant disease. In addition, many of the complex interrelationships between DNA damage, DNA repair, and alterations of gene expression in response to DNA damage have been defined. Techniques for modulating DNA damage and cytotoxicity using schedule-specific cytotoxic combinations, DNA repair inhibitors, cell-cycle manipulations, and adjunctive noncytotoxic drug therapy are being developed, and critical therapeutic targets have been identified within tumor-cell subpopulations and genomic DNA alike. Most importantly, methods for predicting clinical response to cytotoxic therapy using both in vitro markers of tumor-cell sensitivity and in vivo measurements of drug-induced DNA damage are now becoming a reality. These advances can be expected to provide a strong foundation for the development of innovative cytotoxic drug strategies over the next decade.

scholarly journals Acquired temozolomide resistance in MGMT-deficient glioblastoma cells is associated with regulation of DNA repair by DHC2

Brain ◽  
2019 ◽  
Vol 142 (8) ◽  
pp. 2352-2366 ◽  
Author(s):  
Guo-zhong Yi ◽  
Guanglong Huang ◽  
Manlan Guo ◽  
Xi’an Zhang ◽  
Hai Wang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Methyltransferase ◽  
Molecular Mechanisms ◽  
Progression Free Survival ◽  
Recurrent Glioblastoma ◽  
Dna Lesions ◽  
Dna Repair Proteins

Abstract The acquisition of temozolomide resistance is a major clinical challenge for glioblastoma treatment. Chemoresistance in glioblastoma is largely attributed to repair of temozolomide-induced DNA lesions by O6-methylguanine-DNA methyltransferase (MGMT). However, some MGMT-deficient glioblastomas are still resistant to temozolomide, and the underlying molecular mechanisms remain unclear. We found that DYNC2H1 (DHC2) was expressed more in MGMT-deficient recurrent glioblastoma specimens and its expression strongly correlated to poor progression-free survival in MGMT promotor methylated glioblastoma patients. Furthermore, silencing DHC2, both in vitro and in vivo, enhanced temozolomide-induced DNA damage and significantly improved the efficiency of temozolomide treatment in MGMT-deficient glioblastoma. Using a combination of subcellular proteomics and in vitro analyses, we showed that DHC2 was involved in nuclear localization of the DNA repair proteins, namely XPC and CBX5, and knockdown of either XPC or CBX5 resulted in increased temozolomide-induced DNA damage. In summary, we identified the nuclear transportation of DNA repair proteins by DHC2 as a critical regulator of acquired temozolomide resistance in MGMT-deficient glioblastoma. Our study offers novel insights for improving therapeutic management of MGMT-deficient glioblastoma.

scholarly journals RuvAB and RecG Are Not Essential for the Recovery of DNA Synthesis Following UV-Induced DNA Damage in Escherichia coli

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1631-1640 ◽  
Author(s):  
Janet R Donaldson ◽  
Charmain T Courcelle ◽  
Justin Courcelle
Keyword(s):  
Dna Damage ◽  
Dna Synthesis ◽  
Dna Lesions ◽  
Replication Forks ◽  
Wild Type ◽  
Replication Machinery ◽  
Dna Junctions ◽  
Fork Regression

Abstract Ultraviolet light induces DNA lesions that block the progression of the replication machinery. Several models speculate that the resumption of replication following disruption by UV-induced DNA damage requires regression of the nascent DNA or migration of the replication machinery away from the blocking lesion to allow repair or bypass of the lesion to occur. Both RuvAB and RecG catalyze branch migration of three- and four-stranded DNA junctions in vitro and are proposed to catalyze fork regression in vivo. To examine this possibility, we characterized the recovery of DNA synthesis in ruvAB and recG mutants. We found that in the absence of either RecG or RuvAB, arrested replication forks are maintained and DNA synthesis is resumed with kinetics that are similar to those in wild-type cells. The data presented here indicate that RecG- or RuvAB-catalyzed fork regression is not essential for DNA synthesis to resume following arrest by UV-induced DNA damage in vivo.

scholarly journals Simultaneous targeting of DNA replication and homologous recombination in glioblastoma with a polyether ionophore

2019 ◽  
Author(s):  
Yi Chieh Lim ◽  
Kathleen S Ensbey ◽  
Carolin Offenhäuser ◽  
Rochelle C J D’souza ◽  
Jason K Cullen ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
First Generation ◽  
Ex Vivo ◽  
Drug Efficacy ◽  
Tumor Formation ◽  
Dna Lesions ◽  
Dual Functions

Abstract Background Despite significant endeavor having been applied to identify effective therapies to treat glioblastoma (GBM), survival outcomes remain intractable. The greatest nonsurgical benefit arises from radiotherapy, though tumors typically recur due to robust DNA repair. Patients could therefore benefit from therapies with the potential to prevent DNA repair and synergize with radiotherapy. In this work, we investigated the potential of salinomycin to enhance radiotherapy and further uncover novel dual functions of this ionophore to induce DNA damage and prevent repair. Methods In vitro primary GBM models and ex vivo GBM patient explants were used to determine the mechanism of action of salinomycin by immunoblot, flow cytometry, immunofluorescence, immunohistochemistry, and mass spectrometry. In vivo efficacy studies were performed using orthotopic GBM animal xenograft models. Salinomycin derivatives were synthesized to increase drug efficacy and explore structure-activity relationships. Results Here we report novel dual functions of salinomycin. Salinomycin induces toxic DNA lesions and prevents subsequent recovery by targeting homologous recombination (HR) repair. Salinomycin appears to target the more radioresistant GBM stem cell–like population and synergizes with radiotherapy to significantly delay tumor formation in vivo. We further developed salinomycin derivatives which display greater efficacy in vivo while retaining the same beneficial mechanisms of action. Conclusion Our findings highlight the potential of salinomycin to induce DNA lesions and inhibit HR to greatly enhance the effect of radiotherapy. Importantly, first-generation salinomycin derivatives display greater efficacy and may pave the way for clinical testing of these agents.

scholarly journals MicroRNA regulation of the MRN complex impacts DNA damage, cellular senescence and angiogenic signaling

2017 ◽  
Author(s):  
Cristina Espinosa-Diez ◽  
RaeAnna Wilson ◽  
Namita Chatterjee ◽  
Clayton Hudson ◽  
Rebecca Ruhl ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Targeted Delivery ◽  
Genotoxic Stress ◽  
Telomerase Activity ◽  
Loss Of Function ◽  
Mrn Complex ◽  
Vegf Signaling

AbstractMicroRNAs contribute to biological robustness by buffering cellular processes from external perturbations. Here we report an unexpected link between DNA damage response and angiogenic signaling that is buffered by two distinct microRNAs. We demonstrate that genotoxic stress-induced miR-494 and miR-99b inhibit the DNA repair machinery by targeting the MRE11a-RAD50-NBN (MRN) complex. Functionally, gain and loss of function experiments show that miR-494 and miR-99b affect telomerase activity, activate p21 and Rb pathways and diminish angiogenic sproutingin vitroandin vivo. Genetic and pharmacological disruption of VEGFR-2 signaling and the MRN complex reveal a surprising co-dependency of these pathways in regulating endothelial senescence and proliferation. Vascular-targeted delivery of miR-494 decreases both growth factor-induced and tumor angiogenesis in mouse models. Mechanistically, disruption of the MRN complex induced CD44, a known driver of senescence and regulator of VEGF signaling in addition to suppressing IL-13 a stimulator of VEGF signaling. Our work identifies a putative miR-facilitated mechanism by which endothelial cells can be insulated against VEGF signaling to facilitate the onset of senescence and highlight the potential of targeting DNA repair to disrupt pathological angiogenesis.

scholarly journals Targeting dePARylation selectively suppresses DNA repair–defective and PARP inhibitor–resistant malignancies

2019 ◽  
Vol 5 (4) ◽  
pp. eaav4340 ◽  
Author(s):  
Shih-Hsun Chen ◽  
Xiaochun Yu
Keyword(s):  
Dna Repair ◽  
Cancer Cells ◽  
Topoisomerase I ◽  
Catalytic Domain ◽  
Alkylating Agents ◽  
Parp Inhibitor ◽  
Dna Lesions ◽  
Cancer Therapies

While poly(ADP-ribosyl)ation (PARylation) plays an important role in DNA repair, the role of dePARylation in DNA repair remains elusive. Here, we report that a novel small molecule identified from the NCI database, COH34, specifically inhibits poly(ADP-ribose) glycohydrolase (PARG), the major dePARylation enzyme, with nanomolar potency in vitro and in vivo. COH34 binds to the catalytic domain of PARG, thereby prolonging PARylation at DNA lesions and trapping DNA repair factors. This compound induces lethality in cancer cells with DNA repair defects and exhibits antitumor activity in xenograft mouse cancer models. Moreover, COH34 can sensitize tumor cells with DNA repair defects to other DNA-damaging agents, such as topoisomerase I inhibitors and DNA-alkylating agents, which are widely used in cancer chemotherapy. Notably, COH34 also efficiently kills PARP inhibitor–resistant cancer cells. Together, our study reveals the molecular mechanism of PARG in DNA repair and provides an effective strategy for future cancer therapies.

scholarly journals p53 signaling in response to increased DNA damage sensitizes AML1-ETO cells to stress-induced death

Blood ◽  
2008 ◽  
Vol 111 (4) ◽  
pp. 2190-2199 ◽  
Author(s):  
Ondrej Krejci ◽  
Mark Wunderlich ◽  
Hartmut Geiger ◽  
Fu-Sheng Chou ◽  
David Schleimer ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Genetic Alterations ◽  
P53 Pathway ◽  
P53 Response ◽  
Acute Myeloid

Chromosomal translocation (8;21) is present in 10% to 15% of patients with acute myeloid leukemia. Expression of the AML1-ETO (AE) fusion protein alone is not sufficient to induce leukemia, but the nature of the additional genetic alterations is unknown. It is unclear whether AE facilitates acquisition of these cooperating events. We show that AE down-regulates genes involved in multiple DNA repair pathways, potentially through a mechanism involving direct binding at promoter elements, and increases the mutation frequency in vivo. AE cells display increased DNA damage in vitro and have an activated p53 pathway. This results in increased basal apoptosis and enhanced sensitivity to DNA damaging agents. Intriguingly, microarray data indicate that t(8;21) patient samples exhibit decreased expression of DNA repair genes and increased expression of p53 response genes compared with other acute myeloid leukemia (AML) patient samples. Inhibition of the p53 pathway by RNAi increases the resistance of AE cells to DNA damage. We thus speculate that AML1-ETO may facilitate accumulation of genetic alterations by suppressing endogenous DNA repair. It is possible that the superior outcome of t(8;21) patients is partly due to an activated p53 pathway, and that loss of the p53 response pathway is associated with disease progression.

scholarly journals Targeted CRISPR screening identifies PRMT5 as synthetic lethality combinatorial target with gemcitabine in pancreatic cancer cells

2020 ◽  
Author(s):  
Xiaolong Wei ◽  
Jiekun Yang ◽  
Sara J. Adair ◽  
Cem Kuscu ◽  
Kyung Yong Lee ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Dna Repair ◽  
Genetic Alterations ◽  
Model System ◽  
Drug Combinations ◽  
Pancreatic Cancer Cells ◽  
Synergistic Drug Combinations

ABSTRACTPancreatic ductal adenocarcinoma (PDAC) remains one of the most challenging cancer to treat. Due to the asymptomatic nature of the disease and ineffective drug treatment modalities, the survival rate of PDAC patients remains one of the lowest. The recurrent genetic alterations in PDAC are yet to be targeted; therefore, identifying effective therapeutic combinations is desperately needed. Here, we performed an in vivo CRISPR screening in a clinically relevant patient-derived xenograft (PDX) model system to identify synergistic drug combinations for PDAC treatment. Our approach revealed protein arginine methyltransferase gene 5 (PRMT5) as a promising druggable candidate whose inhibition creates synergistic vulnerability of PDAC cells to gemcitabine. Genetic and pharmacological inhibition results indicate that of PRMT5 depletion results in synergistic cytotoxicity with Gem due to depleted replication protein A (RPA) levels and an impaired non-homology end joining (NHEJ) DNA repair. Thus, the novel combination creates conditional lethality through the accumulation of excessive DNA damage and cell death, both in vitro and in vivo. The findings demonstrate that unbiased genetic screenings combined with a clinically relevant model system is an effective approach in identifying synthetic lethal drug combinations for cancer treatment.STATEMENT of SIGNIFICANCEIdentify synergistic drug combinations for PDAC is a significant unmet need. Through CRISPR screening, we discovered and validated that PRMT5 depletion creates synergistic vulnerability of PDAC cells to gemcitabine. Mechanistically, the combination impairs DNA repair, synergistic accumulation of DNA damage and cell death in vitro and in vivo.

scholarly journals POGZ modulates the DNA damage response in a HP1-dependent manner

2021 ◽  
Author(s):  
John Heath ◽  
Estelle Simo Cheyou ◽  
Steven Findlay ◽  
Vincent Luo ◽  
Edgar Pinedo Carpio ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Genome Stability ◽  
Dependent Manner ◽  
Dna Double Strand Breaks ◽  
Humoral Immune ◽  
Damage Response

The heterochromatin protein HP1 plays a central role in the maintenance of genome stability, in particular by promoting homologous recombination (HR)-mediated DNA repair. However, little is still known about how HP1 is controlled during this process. Here, we describe a novel function of the POGO transposable element derived with ZNF domain protein (POGZ) in the regulation of HP1 during the DNA damage response in vitro. POGZ depletion delays the resolution of DNA double-strand breaks (DSBs) and correlates with an increased sensitivity to different DNA damaging agents, including the clinically-relevant Cisplatin and Talazoparib. Mechanistically, POGZ promotes homology-directed DNA repair pathways by retaining the BRCA1/BARD1 complex at DSBs, in a HP1-dependent manner. In vivo CRISPR inactivation of Pogz is embryonic lethal and Pogz haplo-insufficiency (Pogz+/Δ) results in a developmental delay, a deficit in intellectual abilities, a hyperactive behaviour as well as a compromised humoral immune response in mice, recapitulating the main clinical features of the White Sutton syndrome (WHSUS). Importantly, Pogz+/Δ mice are radiosensitive and accumulate DSBs in diverse tissues, including the spleen and the brain. Altogether, our findings identify POGZ as an important player in homology-directed DNA repair both in vitro and in vivo, with clinical implications for the WHSUS.

Spermidine/spermine N1-acetyltransferase overexpression in kidney epithelial cells disrupts polyamine homeostasis, leads to DNA damage, and causes G2 arrest

2007 ◽  
Vol 292 (3) ◽  
pp. C1204-C1215 ◽  
Author(s):  
Kamyar Zahedi ◽  
John J. Bissler ◽  
Zhaohui Wang ◽  
Anuradha Josyula ◽  
Lu Lu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Dna Damage ◽  
Dna Repair ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Dna Lesions ◽  
Cell Cycle Checkpoint ◽  
Cycle Checkpoint

Expression of spermidine/spermine N1-acetyltransferase (SSAT) increases in kidneys subjected to ischemia-reperfusion injury (IRI). Increased expression of SSAT in vitro leads to alterations in cellular polyamine content, depletion of cofactors and precursors of polyamine synthesis, and reduced cell proliferation. In our model system, a >28-fold increase in SSAT levels in HEK-293 cells leads to depletion of polyamines and elevation in the enzymatic activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase, suggestive of a compensatory reaction to increased polyamine catabolism. Increased expression of SSAT also led to DNA damage and G2 arrest. The increased DNA damage was primarily due to the depletion of polyamines. Other factors such as increased production of H2O2 due to polyamine oxidase activity may play a secondary role in the induction of DNA lesions. In response to DNA damage the ATM/ATR → Chk1/2 DNA repair and cell cycle checkpoint pathways were activated, mediating the G2 arrest in SSAT-expressing cells. In addition, the activation of ERK1 and ERK2, which play integral roles in the G2/M transition, is impaired in cells expressing SSAT. These results indicate that the disruption of polyamine homeostasis due to enhanced SSAT activity leads to DNA damage and reduced cell proliferation via activation of DNA repair and cell cycle checkpoint and disruption of Raf → MEK → ERK pathways. We propose that in kidneys subjected to IRI, one mechanism through which increased expression of SSAT may cause cellular injury and organ damage is through induction of DNA damage and the disruption of cell cycle.

Exploring DNA damage responses in human cells with recombinant adenoviral vectors

2007 ◽  
Vol 26 (11) ◽  
pp. 899-906
Author(s):  
Melissa G. Armelini ◽  
Keronninn M. Lima-Bessa ◽  
Maria Carolina N. Marchetto ◽  
Alysson R. Muotri ◽  
Vanessa Chiganças ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mammalian Cells ◽  
Excision Repair ◽  
Adenoviral Vectors ◽  
Dna Lesions ◽  
Human Cells ◽  
Polymerase Eta ◽  
Cell Culture Systems

Recombinant adenoviral vectors provide efficient means for gene transduction in mammalian cells in vitro and in vivo. We are currently using these vectors to transduce DNA repair genes into repair deficient cells, derived from xeroderma pigmentosum (XP) patients. XP is an autosomal syndrome characterized by a high frequency of skin tumors, especially in areas exposed to sunlight, and, occasionally, developmental and neurological abnormalities. XP cells are deficient in nucleotide excision repair (affecting one of the seven known XP genes, xpa to xpg) or in DNA replication of DNA lesions (affecting DNA polymerase eta, xpv). The adenovirus approach allows the investigation of different consequences of DNA lesions in cell genomes. Adenoviral vectors carrying several xp and photolyases genes have been constructed and successfully tested in cell culture systems and in vivo directly in the skin of knockout model mice. This review summarizes these recent data and proposes the use of recombinant adenoviruses as tools to investigate the mechanisms that provide protection against DNA damage in human cells, as well as to better understand the higher predisposition of XP patients to cancer. Human & Experimental Toxicology (2007) 26, 899—906

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