Reduced Efficiency of DNA Repair and Antioxidant Defense Promotes the Accumulation of DNA Damage during Cell Senescence

Tissues and organs undergo structural deterioration and functional decline during aging. DNA damage is considered a major cause of stem cell senescence. Although stem cells develop sophisticated DNA repair systems, when the intrinsic and extrinsic insults exceed the DNA repair capacity, cellular senescence, and age-related diseases inevitably occur. Therefore, the prevention and alleviation of DNA damage is an alternative to DNA repair in attenuating stem cell senescence and preventing age-related diseases. Pre-B-cell leukaemia homeobox 1 (PBX1) participates in maintaining the pluripotency of human embryonic and haematopoietic stem cells. Our recent studies showed that PBX1 promotes hair follicle-derived mesenchymal stem cell (HF-MSC) proliferation, decreases cellular senescence and apoptosis, and enhances induced pluripotent stem cell generation. Whether PBX1 attenuates HF-MSC senescence and apoptosis by alleviating DNA damage or by enhancing DNA repair remains unknown. In this study, we aimed to determine the effects of PBX1 on the intrinsic ROS or extrinsic H2O2-induced cellular senescence of HF-MSCs. To this end, we generated HF-MSCs overexpressing either PBX1, or poly (ADP-ribose) polymerase 1, or both. Our results showed that PBX1 overexpression attenuates HF-MSC senescence and apoptosis by alleviating reactive oxygen species (ROS)-mediated DNA damage instead of enhancing DNA repair. This is the first study to report that PBX1 attenuates stem cell senescence and apoptosis by alleviating DNA damage. It provides new insight into the mechanism of stem cell senescence and lays the foundation for the development of strategies for age-related disease prevention and treatment, and in particular, hair follicle repair and regeneration.

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Long-term efficacy of a new medical device containing Fernblock® and DNA repair enzyme complex in the treatment and prevention of cancerization field in patients with actinic keratosis.

Journal of Current Medical Research and Opinion ◽

10.15520/jcmro.v2i02.129 ◽

2019 ◽

Vol 2 (02) ◽

pp. 80-89

Author(s):

Blanca De Unamuno Bustos ◽

Natalia Chaparr´´o Aguilera ◽

Inmaculada Azorín García ◽

Anaid Calle Andrino ◽

Margarita Llavador Ros ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Medical Device ◽

Actinic Keratosis ◽

Statistical Significance ◽

Dna Lesions ◽

Enzyme Complex ◽

Repair Enzyme ◽

P53 Expression ◽

Cancerization Field

Actinic keratosis (AKs) are part of the cancerization field, a region adjacent to AKs containing subclinical and histologically abnormal epidermal tissue due to Ultraviolet (UV)-induced DNA damage. The photoproducts as consequence of DNA damage induced by UV are mainly cyclobutane pyrimidine dimers (CPDs). Fernblock® demonstrated in previous studies significant reduction of the number of CPDs induced by UV radiation. Photolyases are a specific group of enzymes that remove the major UV-induced DNA lesions by a mechanism called photo-reactivation. A monocentric, prospective, controlled, and double blind interventional study was performed to evaluate the effect of a new medical device (NMD) containing a DNA-repair enzyme complex (photolyases, endonucleases and glycosilases), a combination of UV-filters, and Fernblock® in the treatment of the cancerization field in 30 AK patients after photodynamic therapy. Patients were randomized into two groups: patients receiving a standard sunscreen (SS) andpatients receiving the NMD. Clinical, dermoscopic, reflectance confocal microscopy (RCM) and histological evaluations were performed. An increase of AKs was noted in all groups after three months of PDT without significant differences between them (p=0.476). A significant increase in the number of AKs was observed in SS group after six (p=0.026) and twelve months of PDT (p=0.038); however, this increase did not reach statistical significance in the NMD group. Regarding RCM evaluation, honeycomb pattern assessment after twelve months of PDT showed significant differences in the extension and grade of the atypia in the NMD group compared to SS group (p=0.030 and p=0.026, respectively). Concerning histopathological evaluation, keratinocyte atypia grade improved from baseline to six months after PDT in all the groups, with no statistically significant differences between the groups. Twelve months after PDT, p53 expression was significantly lower in the NMD group compared to SS group (p=0.028). The product was well-tolerated, with no serious adverse events reported. Our results provide evidence of the utility of this NMD in the improvement of the cancerization field and in the prevention of the development of new AKs.

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A Role for Histone H2B During Repair of UV-Induced DNA Damage in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/160.4.1375 ◽

2002 ◽

Vol 160 (4) ◽

pp. 1375-1387

Author(s):

Emmanuelle M D Martini ◽

Scott Keeney ◽

Mary Ann Osley

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Chromatin Structure ◽

Specific Effect ◽

Cell Killing ◽

Cyclobutane Pyrimidine Dimers ◽

Histone H2b ◽

Uv Sensitivity ◽

Pyrimidine Dimers

Abstract To investigate the role of the nucleosome during repair of DNA damage in yeast, we screened for histone H2B mutants that were sensitive to UV irradiation. We have isolated a new mutant, htb1-3, that shows preferential sensitivity to UV-C. There is no detectable difference in bulk chromatin structure or in the number of UV-induced cis-syn cyclobutane pyrimidine dimers (CPD) between HTB1 and htb1-3 strains. These results suggest a specific effect of this histone H2B mutation in UV-induced DNA repair processes rather than a global effect on chromatin structure. We analyzed the UV sensitivity of double mutants that contained the htb1-3 mutation and mutations in genes from each of the three epistasis groups of RAD genes. The htb1-3 mutation enhanced UV-induced cell killing in rad1Δ and rad52Δ mutants but not in rad6Δ or rad18Δ mutants, which are defective in postreplicational DNA repair (PRR). When combined with other mutations that affect PRR, the histone mutation increased the UV sensitivity of strains with defects in either the error-prone (rev1Δ) or error-free (rad30Δ) branches of PRR, but did not enhance the UV sensitivity of a strain with a rad5Δ mutation. When combined with a ubc13Δ mutation, which is also epistatic with rad5Δ, the htb1-3 mutation enhanced UV-induced cell killing. These results suggest that histone H2B acts in a novel RAD5-dependent branch of PRR.

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Environmentally Relevant Mixture of Pesticides Affect Mobility and DNA Integrity of Early Life Stages of Rainbow Trout (Oncorhynchus mykiss)

Toxics ◽

10.3390/toxics9080174 ◽

2021 ◽

Vol 9 (8) ◽

pp. 174

Author(s):

Shannon Weeks Santos ◽

Jérôme Cachot ◽

Bettie Cormier ◽

Nicolas Mazzella ◽

Pierre-Yves Gourves ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Protein Carbonyl ◽

Swimming Activity ◽

Mitochondrial Metabolism ◽

Pesticide Mixture ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Mixture Concentration

The aim of this study was to analyze the impact of three concentrations of a pesticide mixture on the first development stages of rainbow trout (Oncorhynchus mykiss). The mixture was made up of three commonly used pesticides in viticulture: glyphosate (GLY), chlorpyrifos (CPF) and copper sulfate (Cu). Eyed stage embryos were exposed for 3 weeks to three concentrations of the pesticide mixture. Lethal and sub-lethal effects were assessed through a number of phenotypic and molecular endpoints including survival, hatching delay, hatching success, biometry, swimming activity, DNA damage (Comet assay), lipid peroxidation (TBARS), protein carbonyl content and gene expression. Ten target genes involved in antioxidant defenses, DNA repair, mitochondrial metabolism and apoptosis were analyzed using real-time RT-qPCR. No significant increase of mortality, half-hatch, growth defects, TBARS and protein carbonyl contents were observed whatever the pesticide mixture concentration. In contrast, DNA damage and swimming activity were significantly more elevated at the highest pesticide mixture concentration. Gene transcription was up-regulated for genes involved in detoxification (gst and mt1), DNA repair (ogg1), mitochondrial metabolism (cox1 and 12S), and cholinergic system (ache). This study highlighted the induction of adaptive molecular and behavioral responses of rainbow trout larvae when exposed to environmentally realistic concentrations of a mixture of pesticides.

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HPF1 remodels the active site of PARP1 to enable the serine ADP-ribosylation of histones

Nature Communications ◽

10.1038/s41467-021-21302-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Fa-Hui Sun ◽

Peng Zhao ◽

Nan Zhang ◽

Lu-Lu Kong ◽

Catherine C. L. Wong ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Active Site ◽

Negative Charge ◽

Structural Data ◽

Dna Breaks ◽

Adp Ribosylation ◽

Local Conformation ◽

Key Residues ◽

Structural Insights

AbstractUpon binding to DNA breaks, poly(ADP-ribose) polymerase 1 (PARP1) ADP-ribosylates itself and other factors to initiate DNA repair. Serine is the major residue for ADP-ribosylation upon DNA damage, which strictly depends on HPF1. Here, we report the crystal structures of human HPF1/PARP1-CAT ΔHD complex at 1.98 Å resolution, and mouse and human HPF1 at 1.71 Å and 1.57 Å resolution, respectively. Our structures and mutagenesis data confirm that the structural insights obtained in a recent HPF1/PARP2 study by Suskiewicz et al. apply to PARP1. Moreover, we quantitatively characterize the key residues necessary for HPF1/PARP1 binding. Our data show that through salt-bridging to Glu284/Asp286, Arg239 positions Glu284 to catalyze serine ADP-ribosylation, maintains the local conformation of HPF1 to limit PARP1 automodification, and facilitates HPF1/PARP1 binding by neutralizing the negative charge of Glu284. These findings, along with the high-resolution structural data, may facilitate drug discovery targeting PARP1.

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Platinum Complexes in Colorectal Cancer and Other Solid Tumors

Cancers ◽

10.3390/cancers13092073 ◽

2021 ◽

Vol 13 (9) ◽

pp. 2073

Author(s):

Beate Köberle ◽

Sarah Schoch

Keyword(s):

Colorectal Cancer ◽

Dna Damage ◽

Dna Repair ◽

Cancer Cells ◽

Cisplatin Resistance ◽

Platinum Complexes ◽

Dna Lesions ◽

Dna Damage Signaling ◽

Repair Mechanisms ◽

P53 Inactivation

Cisplatin is one of the most commonly used drugs for the treatment of various solid neoplasms, including testicular, lung, ovarian, head and neck, and bladder cancers. Unfortunately, the therapeutic efficacy of cisplatin against colorectal cancer is poor. Various mechanisms appear to contribute to cisplatin resistance in cancer cells, including reduced drug accumulation, enhanced drug detoxification, modulation of DNA repair mechanisms, and finally alterations in cisplatin DNA damage signaling preventing apoptosis in cancer cells. Regarding colorectal cancer, defects in mismatch repair and altered p53-mediated DNA damage signaling are the main factors controlling the resistance phenotype. In particular, p53 inactivation appears to be associated with chemoresistance and poor prognosis. To overcome resistance in cancers, several strategies can be envisaged. Improved cisplatin analogues, which retain activity in resistant cancer, might be applied. Targeting p53-mediated DNA damage signaling provides another therapeutic strategy to circumvent cisplatin resistance. This review provides an overview on the DNA repair pathways involved in the processing of cisplatin damage and will describe signal transduction from cisplatin DNA lesions, with special attention given to colorectal cancer cells. Furthermore, examples for improved platinum compounds and biochemical modulators of cisplatin DNA damage signaling will be presented in the context of colon cancer therapy.

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DNA Damage Response in Multiple Myeloma: The Role of the Tumor Microenvironment

Cancers ◽

10.3390/cancers13030504 ◽

2021 ◽

Vol 13 (3) ◽

pp. 504

Author(s):

Takayuki Saitoh ◽

Tsukasa Oda

Keyword(s):

Multiple Myeloma ◽

Dna Damage ◽

Dna Repair ◽

Tumor Microenvironment ◽

Dna Damage Response ◽

Genetic Instability ◽

Dna Repair Mechanisms ◽

Damage Response ◽

Repair Mechanisms

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by genomic instability. MM cells present various forms of genetic instability, including chromosomal instability, microsatellite instability, and base-pair alterations, as well as changes in chromosome number. The tumor microenvironment and an abnormal DNA repair function affect genetic instability in this disease. In addition, states of the tumor microenvironment itself, such as inflammation and hypoxia, influence the DNA damage response, which includes DNA repair mechanisms, cell cycle checkpoints, and apoptotic pathways. Unrepaired DNA damage in tumor cells has been shown to exacerbate genomic instability and aberrant features that enable MM progression and drug resistance. This review provides an overview of the DNA repair pathways, with a special focus on their function in MM, and discusses the role of the tumor microenvironment in governing DNA repair mechanisms.

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The Interactions of DNA Repair, Telomere Homeostasis, and p53 Mutational Status in Solid Cancers: Risk, Prognosis, and Prediction

Cancers ◽

10.3390/cancers13030479 ◽

2021 ◽

Vol 13 (3) ◽

pp. 479

Author(s):

Pavel Vodicka ◽

Ladislav Andera ◽

Alena Opattova ◽

Ludmila Vodickova

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Dna Repair ◽

Dna Lesions ◽

Cell Cycle Checkpoint ◽

Solid Cancer ◽

Genomic Integrity ◽

Repair Capacity ◽

Mutational Status ◽

Telomere Homeostasis

The disruption of genomic integrity due to the accumulation of various kinds of DNA damage, deficient DNA repair capacity, and telomere shortening constitute the hallmarks of malignant diseases. DNA damage response (DDR) is a signaling network to process DNA damage with importance for both cancer development and chemotherapy outcome. DDR represents the complex events that detect DNA lesions and activate signaling networks (cell cycle checkpoint induction, DNA repair, and induction of cell death). TP53, the guardian of the genome, governs the cell response, resulting in cell cycle arrest, DNA damage repair, apoptosis, and senescence. The mutational status of TP53 has an impact on DDR, and somatic mutations in this gene represent one of the critical events in human carcinogenesis. Telomere dysfunction in cells that lack p53-mediated surveillance of genomic integrity along with the involvement of DNA repair in telomeric DNA regions leads to genomic instability. While the role of individual players (DDR, telomere homeostasis, and TP53) in human cancers has attracted attention for some time, there is insufficient understanding of the interactions between these pathways. Since solid cancer is a complex and multifactorial disease with considerable inter- and intra-tumor heterogeneity, we mainly dedicated this review to the interactions of DNA repair, telomere homeostasis, and TP53 mutational status, in relation to (a) cancer risk, (b) cancer progression, and (c) cancer therapy.

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Harnessing the Nucleolar DNA Damage Response in Cancer Therapy

Genes ◽

10.3390/genes12081156 ◽

2021 ◽

Vol 12 (8) ◽

pp. 1156

Author(s):

Jiachen Xuan ◽

Kezia Gitareja ◽

Natalie Brajanovski ◽

Elaine Sanij

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Cancer Therapy ◽

Dna Damage Response ◽

Rrna Genes ◽

Rrna Synthesis ◽

Pol I ◽

Clinical Investigations ◽

Damage Response ◽

Synthesis And Processing

The nucleoli are subdomains of the nucleus that form around actively transcribed ribosomal RNA (rRNA) genes. They serve as the site of rRNA synthesis and processing, and ribosome assembly. There are 400–600 copies of rRNA genes (rDNA) in human cells and their highly repetitive and transcribed nature poses a challenge for DNA repair and replication machineries. It is only in the last 7 years that the DNA damage response and processes of DNA repair at the rDNA repeats have been recognized to be unique and distinct from the classic response to DNA damage in the nucleoplasm. In the last decade, the nucleolus has also emerged as a central hub for coordinating responses to stress via sequestering tumor suppressors, DNA repair and cell cycle factors until they are required for their functional role in the nucleoplasm. In this review, we focus on features of the rDNA repeats that make them highly vulnerable to DNA damage and the mechanisms by which rDNA damage is repaired. We highlight the molecular consequences of rDNA damage including activation of the nucleolar DNA damage response, which is emerging as a unique response that can be exploited in anti-cancer therapy. In this review, we focus on CX-5461, a novel inhibitor of Pol I transcription that induces the nucleolar DNA damage response and is showing increasing promise in clinical investigations.

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Ancient Sturgeons Possess Effective DNA Repair Mechanisms: Influence of Model Genotoxicants on Embryo Development of Sterlet, Acipenser ruthenus

International Journal of Molecular Sciences ◽

10.3390/ijms22010006 ◽

2020 ◽

Vol 22 (1) ◽

pp. 6

Author(s):

Ievgeniia Gazo ◽

Roman Franěk ◽

Radek Šindelka ◽

Ievgen Lebeda ◽

Sahana Shivaramu ◽

...

Keyword(s):

Gene Expression ◽

Dna Damage ◽

Dna Repair ◽

Embryo Development ◽

Hatching Rate ◽

Embryo Survival ◽

Dna Repair Mechanisms ◽

Acipenser Ruthenus ◽

Repair Mechanisms ◽

Sterlet Acipenser Ruthenus

DNA damage caused by exogenous or endogenous factors is a common challenge for developing fish embryos. DNA damage repair (DDR) pathways help organisms minimize adverse effects of DNA alterations. In terms of DNA repair mechanisms, sturgeons represent a particularly interesting model due to their exceptional genome plasticity. Sterlet (Acipenser ruthenus) is a relatively small species of sturgeon. The goal of this study was to assess the sensitivity of sterlet embryos to model genotoxicants (camptothecin, etoposide, and benzo[a]pyrene), and to assess DDR responses. We assessed the effects of genotoxicants on embryo survival, hatching rate, DNA fragmentation, gene expression, and phosphorylation of H2AX and ATM kinase. Exposure of sterlet embryos to 1 µM benzo[a]pyrene induced low levels of DNA damage accompanied by ATM phosphorylation and xpc gene expression. Conversely, 20 µM etoposide exposure induced DNA damage without activation of known DDR pathways. Effects of 10 nM camptothecin on embryo development were stage-specific, with early stages, before gastrulation, being most sensitive. Overall, this study provides foundational information for future investigation of sterlet DDR pathways.

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