scholarly journals Topoisomerase I-driven repair of UV-induced damage in NER-deficient cells

2020 ◽  
pp. 201920165
Author(s):  
Liton Kumar Saha ◽  
Mitsuo Wakasugi ◽  
Salma Akter ◽  
Rajendra Prasad ◽  
Samuel H. Wilson ◽  
...  
Keyword(s):  
Dna Repair ◽  
Cancer Cells ◽  
Topoisomerase I ◽  
Excision Repair ◽  
Skin Fibroblasts ◽  
Patch Repair ◽  
Repair Pathway ◽  
Repair Synthesis ◽  
Cellular Tolerance ◽  
Uv Lesions

Nucleotide excision repair (NER) removes helix-destabilizing adducts including ultraviolet (UV) lesions, cyclobutane pyrimidine dimers (CPDs), and pyrimidine (6–4) pyrimidone photoproducts (6–4PPs). In comparison with CPDs, 6–4PPs have greater cytotoxicity and more strongly destabilizing properties of the DNA helix. It is generally believed that NER is the only DNA repair pathway that removes the UV lesions as evidenced by the previous data since no repair of UV lesions was detected in NER-deficient skin fibroblasts. Topoisomerase I (TOP1) constantly creates transient single-strand breaks (SSBs) releasing the torsional stress in genomic duplex DNA. Stalled TOP1-SSB complexes can form near DNA lesions including abasic sites and ribonucleotides embedded in chromosomal DNA. Here we show that base excision repair (BER) increases cellular tolerance to UV independently of NER in cancer cells. UV lesions irreversibly trap stable TOP1-SSB complexes near the UV damage in NER-deficient cells, and the resulting SSBs activate BER. Biochemical experiments show that 6–4PPs efficiently induce stable TOP1-SSB complexes, and the long-patch repair synthesis of BER removes 6–4PPs downstream of the SSB. Furthermore, NER-deficient cancer cell lines remove 6–4PPs within 24 h, but not CPDs, and the removal correlates with TOP1 expression. NER-deficient skin fibroblasts weakly express TOP1 and show no detectable repair of 6–4PPs. Remarkably, the ectopic expression of TOP1 in these fibroblasts led them to completely repair 6–4PPs within 24 h. In conclusion, we reveal a DNA repair pathway initiated by TOP1, which significantly contributes to cellular tolerance to UV-induced lesions particularly in malignant cancer cells overexpressing TOP1.

scholarly journals MiR223-3p promotes synthetic lethality in BRCA1-deficient cancers

2019 ◽  
Vol 116 (35) ◽  
pp. 17438-17443 ◽  
Author(s):  
Gayathri Srinivasan ◽  
Elizabeth A. Williamson ◽  
Kimi Kong ◽  
Aruna S. Jaiswal ◽  
Guangcun Huang ◽  
...  
Keyword(s):  
Dna Repair ◽  
Cancer Cells ◽  
Synthetic Lethality ◽  
Negative Regulator ◽  
Nonhomologous End Joining ◽  
Chromosomal Translocations ◽  
Replication Forks ◽  
Repair Pathway ◽  
End Joining ◽  
Parp1 Inhibitors

Defects in DNA repair give rise to genomic instability, leading to neoplasia. Cancer cells defective in one DNA repair pathway can become reliant on remaining repair pathways for survival and proliferation. This attribute of cancer cells can be exploited therapeutically, by inhibiting the remaining repair pathway, a process termed synthetic lethality. This process underlies the mechanism of the Poly-ADP ribose polymerase-1 (PARP1) inhibitors in clinical use, which target BRCA1 deficient cancers, which is indispensable for homologous recombination (HR) DNA repair. HR is the major repair pathway for stressed replication forks, but when BRCA1 is deficient, stressed forks are repaired by back-up pathways such as alternative nonhomologous end-joining (aNHEJ). Unlike HR, aNHEJ is nonconservative, and can mediate chromosomal translocations. In this study we have found that miR223-3p decreases expression of PARP1, CtIP, and Pso4, each of which are aNHEJ components. In most cells, high levels of microRNA (miR) 223–3p repress aNHEJ, decreasing the risk of chromosomal translocations. Deletion of the miR223 locus in mice increases PARP1 levels in hematopoietic cells and enhances their risk of unprovoked chromosomal translocations. We also discovered that cancer cells deficient in BRCA1 or its obligate partner BRCA1-Associated Protein-1 (BAP1) routinely repress miR223-3p to permit repair of stressed replication forks via aNHEJ. Reconstituting the expression of miR223-3p in BRCA1- and BAP1-deficient cancer cells results in reduced repair of stressed replication forks and synthetic lethality. Thus, miR223-3p is a negative regulator of the aNHEJ DNA repair and represents a therapeutic pathway for BRCA1- or BAP1-deficient cancers.

scholarly journals PARP Inhibitors as a Therapeutic Agent for Homologous Recombination Deficiency in Breast Cancers

2019 ◽  
Vol 8 (4) ◽  
pp. 435 ◽  
Author(s):  
Man Keung ◽  
Yanyuan Wu ◽  
Jaydutt Vadgama
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Cancer Cells ◽  
Anticancer Agents ◽  
Excision Repair ◽  
Parp Inhibitor ◽  
Predictive Biomarkers ◽  
Parp Inhibitors ◽  
Homologous Recombination Deficiency ◽  
Repair Pathways

Poly (ADP-ribose) polymerases (PARPs) play an important role in various cellular processes, such as replication, recombination, chromatin remodeling, and DNA repair. Emphasizing PARP’s role in facilitating DNA repair, the PARP pathway has been a target for cancer researchers in developing compounds which selectively target cancer cells and increase sensitivity of cancer cells to other anticancer agents, but which also leave normal cells unaffected. Since certain tumors (BRCA1/2 mutants) have deficient homologous recombination repair pathways, they depend on PARP-mediated base excision repair for survival. Thus, inhibition of PARP is a promising strategy to selectively kill cancer cells by inactivating complementary DNA repair pathways. Although PARP inhibitor therapy has predominantly targeted BRCA-mutated cancers, this review also highlights the growing conversation around PARP inhibitor treatment for non-BRCA-mutant tumors, those which exhibit BRCAness and homologous recombination deficiency. We provide an update on the field’s progress by considering PARP inhibitor mechanisms, predictive biomarkers, and clinical trials of PARP inhibitors in development. Bringing light to these findings would provide a basis for expanding the use of PARP inhibitors beyond BRCA-mutant breast tumors.

scholarly journals Tautomerization-dependent recognition and excision of oxidation damage in base-excision DNA repair

2016 ◽  
Vol 113 (28) ◽  
pp. 7792-7797 ◽  
Author(s):  
Chenxu Zhu ◽  
Lining Lu ◽  
Jun Zhang ◽  
Zongwei Yue ◽  
Jinghui Song ◽  
...  
Keyword(s):  
Dna Repair ◽  
Excision Repair ◽  
Mammalian Genome ◽  
Dna Bases ◽  
Repair Pathway ◽  
Thymine Glycol ◽  
Base Excision ◽  
Oxidation Damage ◽  
Biochemical Analyses ◽  
Base Excision Dna Repair

NEIL1 (Nei-like 1) is a DNA repair glycosylase guarding the mammalian genome against oxidized DNA bases. As the first enzymes in the base-excision repair pathway, glycosylases must recognize the cognate substrates and catalyze their excision. Here we present crystal structures of human NEIL1 bound to a range of duplex DNA. Together with computational and biochemical analyses, our results suggest that NEIL1 promotes tautomerization of thymine glycol (Tg)—a preferred substrate—for optimal binding in its active site. Moreover, this tautomerization event also facilitates NEIL1-catalyzed Tg excision. To our knowledge, the present example represents the first documented case of enzyme-promoted tautomerization for efficient substrate recognition and catalysis in an enzyme-catalyzed reaction.

Abstract 267: Targeting the alt-NHEJ DNA repair pathway selectively sensitizes KRAS-mutant cancer cells to chemotherapy

2019 ◽  
Author(s):  
Patricia S. Haehnel ◽  
Sarah Swoboda ◽  
Nadine Lehmann ◽  
Sebastian Rosigkeit ◽  
Hernike Gothe ◽  
...  
Keyword(s):  
Dna Repair ◽  
Cancer Cells ◽  
Repair Pathway

Abstract 267: Targeting the alt-NHEJ DNA repair pathway selectively sensitizes KRAS-mutant cancer cells to chemotherapy

2019 ◽  
Author(s):  
Patricia S. Haehnel ◽  
Sarah Swoboda ◽  
Nadine Lehmann ◽  
Sebastian Rosigkeit ◽  
Hernike Gothe ◽  
...  
Keyword(s):  
Dna Repair ◽  
Cancer Cells ◽  
Repair Pathway

scholarly journals DNA Repair Functions That Control Sensitivity to Topoisomerase-Targeting Drugs

2004 ◽  
Vol 3 (1) ◽  
pp. 82-90 ◽  
Author(s):  
Mobeen Malik ◽  
John L. Nitiss
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Topoisomerase I ◽  
Topoisomerase Ii ◽  
Excision Repair ◽  
Dna Strand Breaks ◽  
Dna Topology ◽  
Strand Breaks ◽  
Wide Range ◽  
Dna Strand

ABSTRACT DNA topoisomerases play critical roles in a wide range of cellular processes by altering DNA topology to facilitate replication, transcription, and chromosome segregation. Topoisomerases alter DNA topology by introducing transient DNA strand breaks that involve a covalent protein DNA intermediate. Many agents have been found to prevent the religation of DNA strand breaks induced by the enzymes, thereby converting the enzymes into DNA-damaging agents. Repair of the DNA damage induced by topoisomerases is significant in understanding drug resistance arising following treatment with topoisomerase-targeting drugs. We have used the fission yeast Schizosaccharomyces pombe to identify DNA repair pathways that are important for cell survival following drug treatment. S. pombe strains carrying mutations in genes required for homologous recombination such as rad22A or rad32 (homologues of RAD52 and MRE11) are hypersensitive to drugs targeting either topoisomerase I or topoisomerase II. In contrast to results observed with Saccharomyces cerevisiae, S. pombe strains defective in nucleotide excision repair are also hypersensitive to topoisomerase-targeting agents. The loss of DNA replication or DNA damage checkpoints also sensitizes cells to both topoisomerase I and topoisomerase II inhibitors. Finally, repair genes (such as the S. pombe rad8+ gene) with no obvious homologs in other systems also play important roles in causing sensitivity to topoisomerase drugs. Since the pattern of sensitivity is distinct from that seen with other systems (such as the S. cerevisiae system), our results highlight the usefulness of S. pombe in understanding how cells deal with the unique DNA damage induced by topoisomerases.

scholarly journals Valproic acid causes radiosensitivity of breast cancer cells via disrupting the DNA repair pathway

2016 ◽  
Vol 5 (3) ◽  
pp. 859-870 ◽  
Author(s):  
Yue Luo ◽  
Hui Wang ◽  
Xipeng Zhao ◽  
Chao Dong ◽  
Fengmei Zhang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Valproic Acid ◽  
Dna Repair ◽  
Cancer Cells ◽  
Histone Deacetylase ◽  
Breast Cancer Cells ◽  
Histone Deacetylase Inhibitors ◽  
Clinical Treatment ◽  
Repair Pathway ◽  
Treatment Of Epilepsy

Valproic acid (VPA) is one of the representative compounds of histone deacetylase inhibitors (HDACis) and is used widely for the clinical treatment of epilepsy and other convulsive diseases.

Nucleotide Excision Repair in the Three Domains of Life

2011 ◽  
Vol 2 (1) ◽  
Author(s):  
David A Farnell
Keyword(s):  
Dna Repair ◽  
Nucleotide Excision Repair ◽  
Xeroderma Pigmentosum ◽  
Excision Repair ◽  
Human Diseases ◽  
Repair Pathway ◽  
Functional Conservation ◽  
Wide Range ◽  
Nucleotide Excision ◽  
Domains Of Life

Nucleotide excision repair (NER) is a vital DNA repair pathway which acts on a wide range of helix-distorting lesions. The importance of this pathway is highlighted by its functional conservation throughout evolution and by several human diseases, such as xeroderma pigmentosum, which are caused by a defective NER pathway. This review summarizes the NER mechanisms present in all three domains of life: eukaryotes, bacteria, and archaea.

Sign in / Sign up

Export Citation Format

Share Document