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Genes & Development Mar 2022DNA repair and DNA damage signaling pathways are critical for the maintenance of genomic stability. Defects of DNA repair and damage signaling contribute to... (Review)
Review
DNA repair and DNA damage signaling pathways are critical for the maintenance of genomic stability. Defects of DNA repair and damage signaling contribute to tumorigenesis, but also render cancer cells vulnerable to DNA damage and reliant on remaining repair and signaling activities. Here, we review the major classes of DNA repair and damage signaling defects in cancer, the genomic instability that they give rise to, and therapeutic strategies to exploit the resulting vulnerabilities. Furthermore, we discuss the impacts of DNA repair defects on both targeted therapy and immunotherapy, and highlight emerging principles for targeting DNA repair defects in cancer therapy.
Topics: DNA Damage; DNA Repair; Genomic Instability; Humans; Immunotherapy; Neoplasms
PubMed: 35318271
DOI: 10.1101/gad.349431.122 -
Cells Jul 2020DNA is the source of genetic information, and preserving its integrity is essential in order to sustain life. The genome is continuously threatened by different types of... (Review)
Review
DNA is the source of genetic information, and preserving its integrity is essential in order to sustain life. The genome is continuously threatened by different types of DNA lesions, such as abasic sites, mismatches, interstrand crosslinks, or single-stranded and double-stranded breaks. As a consequence, cells have evolved specialized DNA damage response (DDR) mechanisms to sustain genome integrity. By orchestrating multilayer signaling cascades specific for the type of lesion that occurred, the DDR ensures that genetic information is preserved overtime. In the last decades, DNA repair mechanisms have been thoroughly investigated to untangle these complex networks of pathways and processes. As a result, key factors have been identified that control and coordinate DDR circuits in time and space. In the first part of this review, we describe the critical processes encompassing DNA damage sensing and resolution. In the second part, we illustrate the consequences of partial or complete failure of the DNA repair machinery. Lastly, we will report examples in which this knowledge has been instrumental to develop novel therapies based on genome editing technologies, such as CRISPR-Cas.
Topics: Animals; Clustered Regularly Interspaced Short Palindromic Repeats; DNA Damage; DNA Repair; Gene Editing; Humans
PubMed: 32664329
DOI: 10.3390/cells9071665 -
Trends in Genetics : TIG Jul 2021Many clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-based genome editing technologies take advantage of Cas... (Review)
Review
Many clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-based genome editing technologies take advantage of Cas nucleases to induce DNA double-strand breaks (DSBs) at desired locations within a genome. Further processing of the DSBs by the cellular DSB repair machinery is then necessary to introduce desired mutations, sequence insertions, or gene deletions. Thus, the accuracy and efficiency of genome editing are influenced by the cellular DSB repair pathways. DSBs are themselves highly genotoxic lesions and as such cells have evolved multiple mechanisms for their repair. These repair pathways include homologous recombination (HR), classical nonhomologous end joining (cNHEJ), microhomology-mediated end joining (MMEJ) and single-strand annealing (SSA). In this review, we briefly highlight CRISPR-Cas9 and then describe the mechanisms of DSB repair. Finally, we summarize recent findings of factors that can influence the choice of DNA repair pathway in response to Cas9-induced DSBs.
Topics: CRISPR-Cas Systems; DNA Breaks, Double-Stranded; DNA End-Joining Repair; DNA Repair; Gene Editing; Genome, Human; Homologous Recombination; Humans; Mutagenesis, Insertional; Signal Transduction
PubMed: 33896583
DOI: 10.1016/j.tig.2021.02.008 -
Signal Transduction and Targeted Therapy May 2020Radiotherapy is one of the most common countermeasures for treating a wide range of tumors. However, the radioresistance of cancer cells is still a major limitation for... (Review)
Review
Radiotherapy is one of the most common countermeasures for treating a wide range of tumors. However, the radioresistance of cancer cells is still a major limitation for radiotherapy applications. Efforts are continuously ongoing to explore sensitizing targets and develop radiosensitizers for improving the outcomes of radiotherapy. DNA double-strand breaks are the most lethal lesions induced by ionizing radiation and can trigger a series of cellular DNA damage responses (DDRs), including those helping cells recover from radiation injuries, such as the activation of DNA damage sensing and early transduction pathways, cell cycle arrest, and DNA repair. Obviously, these protective DDRs confer tumor radioresistance. Targeting DDR signaling pathways has become an attractive strategy for overcoming tumor radioresistance, and some important advances and breakthroughs have already been achieved in recent years. On the basis of comprehensively reviewing the DDR signal pathways, we provide an update on the novel and promising druggable targets emerging from DDR pathways that can be exploited for radiosensitization. We further discuss recent advances identified from preclinical studies, current clinical trials, and clinical application of chemical inhibitors targeting key DDR proteins, including DNA-PKcs (DNA-dependent protein kinase, catalytic subunit), ATM/ATR (ataxia-telangiectasia mutated and Rad3-related), the MRN (MRE11-RAD50-NBS1) complex, the PARP (poly[ADP-ribose] polymerase) family, MDC1, Wee1, LIG4 (ligase IV), CDK1, BRCA1 (BRCA1 C terminal), CHK1, and HIF-1 (hypoxia-inducible factor-1). Challenges for ionizing radiation-induced signal transduction and targeted therapy are also discussed based on recent achievements in the biological field of radiotherapy.
Topics: Cell Cycle Checkpoints; DNA Breaks, Double-Stranded; DNA Repair; Humans; Neoplasm Proteins; Neoplasms; Radiation Tolerance; Radiotherapy; Signal Transduction
PubMed: 32355263
DOI: 10.1038/s41392-020-0150-x -
Molecular Cell Jun 2020Anti-cancer drugs targeting the DNA damage response (DDR) exploit genetic or functional defects in this pathway through synthetic lethal mechanisms. For example, defects... (Review)
Review
Anti-cancer drugs targeting the DNA damage response (DDR) exploit genetic or functional defects in this pathway through synthetic lethal mechanisms. For example, defects in homologous recombination (HR) repair arise in cancer cells through inherited or acquired mutations in BRCA1, BRCA2, or other genes in the Fanconi anemia/BRCA pathway, and these tumors have been shown to be particularly sensitive to inhibitors of the base excision repair (BER) protein poly (ADP-ribose) polymerase (PARP). Recent work has identified additional genomic and functional assays of DNA repair that provide new predictive and pharmacodynamic biomarkers for these targeted therapies. Here, we examine the development of selective agents targeting DNA repair, including PARP inhibitors; inhibitors of the DNA damage kinases ataxia-telangiectasia and Rad3 related (ATR), CHK1, WEE1, and ataxia-telangiectasia mutated (ATM); and inhibitors of classical non-homologous end joining (cNHEJ) and alternative end joining (Alt EJ). We also review the biomarkers that guide the use of these agents and current clinical trials with these therapies.
Topics: Animals; Antineoplastic Agents; Biomarkers, Pharmacological; DNA Damage; DNA End-Joining Repair; DNA Repair; Genes, BRCA1; Homologous Recombination; Humans; Neoplasms; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases
PubMed: 32459988
DOI: 10.1016/j.molcel.2020.04.035 -
Molecular Cell Oct 2022The DNA-PKcs kinase mediates the repair of DNA double-strand breaks via classical non-homologous end joining (NHEJ). DNA-PKcs is also recruited to active replication...
The DNA-PKcs kinase mediates the repair of DNA double-strand breaks via classical non-homologous end joining (NHEJ). DNA-PKcs is also recruited to active replication forks, although a role for DNA-PKcs in the control of fork dynamics is unclear. Here, we identify a crucial role for DNA-PKcs in promoting fork reversal, a process that stabilizes stressed replication forks and protects genome integrity. DNA-PKcs promotes fork reversal and slowing in response to several replication stress-inducing agents in a manner independent of its role in NHEJ. Cells lacking DNA-PKcs activity show increased DNA damage during S-phase and cellular sensitivity to replication stress. Notably, prevention of fork slowing and reversal via DNA-PKcs inhibition efficiently restores chemotherapy sensitivity in BRCA2-deficient mammary tumors with acquired PARPi resistance. Together, our data uncover a new key regulator of fork reversal and show how DNA-PKcs signaling can be manipulated to alter fork dynamics and drug resistance in cancer.
Topics: Drug Resistance, Neoplasm; DNA Breaks, Double-Stranded; DNA Damage; DNA End-Joining Repair; DNA; DNA Replication; DNA Repair
PubMed: 36130596
DOI: 10.1016/j.molcel.2022.08.028 -
Modern Pathology : An Official Journal... Mar 2023The repair of DNA double-stranded breaks relies on the homologous recombination repair pathway and is critical to cell function. However, this pathway can be lost in... (Review)
Review
The repair of DNA double-stranded breaks relies on the homologous recombination repair pathway and is critical to cell function. However, this pathway can be lost in some cancers such as breast, ovarian, endometrial, pancreatic, and prostate cancers. Cancer cells with homologous recombination deficiency (HRD) are sensitive to targeted inhibition of poly-ADP ribose polymerase (PARP), a key component of alternative backup DNA repair pathways. Identifying patients with cancer with HRD biomarkers allows the identification of patients likely to benefit from PARP inhibitor therapies. In this study, we describe the causes of HRD, the underlying molecular changes resulting from HRD that form the basis of different molecular HRD assays, and discuss the issues around their clinical use. This overview is directed toward practicing pathologists wishing to be informed of this new predictive biomarker, as PARP inhibitors are increasingly used in standard care settings.
Topics: Female; Humans; Recombinational DNA Repair; Ovarian Neoplasms; Homologous Recombination; Pathologists; DNA Repair
PubMed: 36788098
DOI: 10.1016/j.modpat.2022.100049 -
Nature Reviews. Molecular Cell Biology Dec 2020Non-homologous DNA end joining (NHEJ) is the predominant repair mechanism of any type of DNA double-strand break (DSB) during most of the cell cycle and is essential for... (Review)
Review
Non-homologous DNA end joining (NHEJ) is the predominant repair mechanism of any type of DNA double-strand break (DSB) during most of the cell cycle and is essential for the development of antigen receptors. Defects in NHEJ result in sensitivity to ionizing radiation and loss of lymphocytes. The most critical step of NHEJ is synapsis, or the juxtaposition of the two DNA ends of a DSB, because all subsequent steps rely on it. Recent findings show that, like the end processing step, synapsis can be achieved through several mechanisms. In this Review, we first discuss repair pathway choice between NHEJ and other DSB repair pathways. We then integrate recent insights into the mechanisms of NHEJ synapsis with updates on other steps of NHEJ, such as DNA end processing and ligation. Finally, we discuss NHEJ-related human diseases, including inherited disorders and neoplasia, which arise from rare failures at different NHEJ steps.
Topics: Animals; DNA Breaks, Double-Stranded; DNA End-Joining Repair; DNA Repair; Disease; Genetic Diseases, Inborn; Humans; Neoplasms; Signal Transduction
PubMed: 33077885
DOI: 10.1038/s41580-020-00297-8 -
The Journal of Clinical Investigation Nov 2022Pediatric high-grade gliomas (pHGGs) are the leading cause of cancer-related deaths in children in the USA. Sixteen percent of hemispheric pediatric and young adult HGGs...
Pediatric high-grade gliomas (pHGGs) are the leading cause of cancer-related deaths in children in the USA. Sixteen percent of hemispheric pediatric and young adult HGGs encode Gly34Arg/Val substitutions in the histone H3.3 (H3.3-G34R/V). The mechanisms by which H3.3-G34R/V drive malignancy and therapeutic resistance in pHGGs remain unknown. Using a syngeneic, genetically engineered mouse model (GEMM) and human pHGG cells encoding H3.3-G34R, we demonstrate that this mutation led to the downregulation of DNA repair pathways. This resulted in enhanced susceptibility to DNA damage and inhibition of the DNA damage response (DDR). We demonstrate that genetic instability resulting from improper DNA repair in G34R-mutant pHGG led to the accumulation of extrachromosomal DNA, which activated the cyclic GMP-AMP synthase/stimulator of IFN genes (cGAS/STING) pathway, inducing the release of immune-stimulatory cytokines. We treated H3.3-G34R pHGG-bearing mice with a combination of radiotherapy (RT) and DNA damage response inhibitors (DDRi) (i.e., the blood-brain barrier-permeable PARP inhibitor pamiparib and the cell-cycle checkpoint CHK1/2 inhibitor AZD7762), and these combinations resulted in long-term survival for approximately 50% of the mice. Moreover, the addition of a STING agonist (diABZl) enhanced the therapeutic efficacy of these treatments. Long-term survivors developed immunological memory, preventing pHGG growth upon rechallenge. These results demonstrate that DDRi and STING agonists in combination with RT induced immune-mediated therapeutic efficacy in G34-mutant pHGG.
Topics: Animals; Child; Humans; Mice; Young Adult; Brain Neoplasms; DNA Repair; Glioma; Histones; Immunity; Mutation; Nucleotidyltransferases; Membrane Proteins; Cytokines; Poly(ADP-ribose) Polymerase Inhibitors
PubMed: 36125896
DOI: 10.1172/JCI154229 -
International Journal of Molecular... Sep 2020Precise gene editing is-or will soon be-in clinical use for several diseases, and more applications are under development. The programmable nuclease Cas9, directed by a... (Review)
Review
Precise gene editing is-or will soon be-in clinical use for several diseases, and more applications are under development. The programmable nuclease Cas9, directed by a single-guide RNA (sgRNA), can introduce double-strand breaks (DSBs) in target sites of genomic DNA, which constitutes the initial step of gene editing using this novel technology. In mammals, two pathways dominate the repair of the DSBs-nonhomologous end joining (NHEJ) and homology-directed repair (HDR)-and the outcome of gene editing mainly depends on the choice between these two repair pathways. Although HDR is attractive for its high fidelity, the choice of repair pathway is biased in a biological context. Mammalian cells preferentially employ NHEJ over HDR through several mechanisms: NHEJ is active throughout the cell cycle, whereas HDR is restricted to S/G2 phases; NHEJ is faster than HDR; and NHEJ suppresses the HDR process. This suggests that definitive control of outcome of the programmed DNA lesioning could be achieved through manipulating the choice of cellular repair pathway. In this review, we summarize the DSB repair pathways, the mechanisms involved in choice selection based on DNA resection, and make progress in the research investigating strategies that favor Cas9-mediated HDR based on the manipulation of repair pathway choice to increase the frequency of HDR in mammalian cells. The remaining problems in improving HDR efficiency are also discussed. This review should facilitate the development of CRISPR/Cas9 technology to achieve more precise gene editing.
Topics: Animals; CRISPR-Cas Systems; Clustered Regularly Interspaced Short Palindromic Repeats; DNA; DNA Breaks, Double-Stranded; DNA End-Joining Repair; DNA Repair; Endonucleases; Gene Editing; Humans; RNA, Guide, CRISPR-Cas Systems; Recombinational DNA Repair
PubMed: 32899704
DOI: 10.3390/ijms21186461