-
Nature Protocols Mar 2023The comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to human. The types of damage detected encompass DNA strand... (Review)
Review
The comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to human. The types of damage detected encompass DNA strand breaks and alkali-labile sites (e.g., apurinic/apyrimidinic sites), alkylated and oxidized nucleobases, DNA-DNA crosslinks, UV-induced cyclobutane pyrimidine dimers and some chemically induced DNA adducts. Depending on the specimen type, there are important modifications to the comet assay protocol to avoid the formation of additional DNA damage during the processing of samples and to ensure sufficient sensitivity to detect differences in damage levels between sample groups. Various applications of the comet assay have been validated by research groups in academia, industry and regulatory agencies, and its strengths are highlighted by the adoption of the comet assay as an in vivo test for genotoxicity in animal organs by the Organisation for Economic Co-operation and Development. The present document includes a series of consensus protocols that describe the application of the comet assay to a wide variety of cell types, species and types of DNA damage, thereby demonstrating its versatility.
Topics: Animals; Humans; Comet Assay; DNA Damage; Pyrimidine Dimers; Eukaryotic Cells; DNA
PubMed: 36707722
DOI: 10.1038/s41596-022-00754-y -
Oncogene Oct 2021POLE, POLD1, and NTHL1 are involved in DNA replication and have recently been recognized as hereditary cancer-predisposing genes, because their alterations are... (Review)
Review
POLE, POLD1, and NTHL1 are involved in DNA replication and have recently been recognized as hereditary cancer-predisposing genes, because their alterations are associated with colorectal cancer and other tumors. POLE/POLD1-associated syndrome shows an autosomal dominant inheritance, whereas NTHL1-associated syndrome follows an autosomal recessive pattern. Although the prevalence of germline monoallelic POLE/POLD1 and biallelic NTHL1 pathogenic variants is low, they determine different phenotypes with a broad tumor spectrum overlapping that of other hereditary conditions like Lynch Syndrome or Familial Adenomatous Polyposis. Endometrial and breast cancers, and probably ovarian and brain tumors are also associated with POLE/POLD1 alterations, while breast cancer and other unusual tumors are correlated with NTHL1 pathogenic variants. POLE-mutated colorectal and endometrial cancers are associated with better prognosis and may show favorable responses to immunotherapy. Since POLE/POLD1-mutated tumors show a high tumor mutational burden producing an increase in neoantigens, the identification of POLE/POLD1 alterations could help select patients suitable for immunotherapy treatment. In this review, we will investigate the role of POLE, POLD1, and NTHL1 genetic variants in cancer predisposition, discussing the potential future therapeutic applications and assessing the utility of performing a routine genetic testing for these genes, in order to implement prevention and surveillance strategies in mutation carriers.
Topics: DNA Polymerase II; DNA Polymerase III; Deoxyribonuclease (Pyrimidine Dimer); Female; Genetic Predisposition to Disease; Humans; Male; Neoplasms; Poly-ADP-Ribose Binding Proteins
PubMed: 34363023
DOI: 10.1038/s41388-021-01984-2 -
Current Problems in Dermatology 2021Sunlight comprises radiation of different wavelengths, of which UVA and UVB are most important with respect to human skin diseases. Next to erythema, edema, and... (Review)
Review
Sunlight comprises radiation of different wavelengths, of which UVA and UVB are most important with respect to human skin diseases. Next to erythema, edema, and sunburns, UV radiation causes skin cancer. UV radiation of any wavelength is now considered as a class I carcinogen to humans. The mutagenic effects of UV radiation depend on DNA damage following direct absorption by nuclear DNA, resulting in cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts that, if not repaired by nucleotide excision repair pathway, result in characteristic UV signature mutations (C→T or CC→TT transition). In addition, increased formation of reactive oxygen species by UV exposure may cause formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine leading to T→G transversion. In addition, UV radiation has been shown to induce a number of immune modulations that largely result in local and potentially also in systemic immunosuppression, which may not only impair control of dysplastic and neoplastic skin lesions but also affect immuno-pathological and infectious skin diseases. Recent find-ings have shown that ambient doses of high-energy visible light, beyond the UV range, may also cause damage to human skin.
Topics: DNA Damage; Humans; Pyrimidine Dimers; Reactive Oxygen Species; Skin; Skin Diseases; Ultraviolet Rays
PubMed: 34698038
DOI: 10.1159/000517592 -
IUCrData Mar 2020In the title compound, CHClNOS, the dihedral angle between the pyrrolo-[1,2-]pyrimidine ring system (r.m.s. deviation = 0.008 Å) and the benzene ring is 80.2 (9)°....
In the title compound, CHClNOS, the dihedral angle between the pyrrolo-[1,2-]pyrimidine ring system (r.m.s. deviation = 0.008 Å) and the benzene ring is 80.2 (9)°. In the crystal, inversion dimers linked by pairs of C-H⋯O inter-actions generate (16) loops. Several aromatic π-π stacking inter-actions between the pyrrolo-[1,2-]pyrimidine rings, as well as separately between the pyrrolo and pyrimidine groups [shortest centroid-centroid separation = 3.5758 (14) Å], help to consolidate the packing.
PubMed: 36339475
DOI: 10.1107/S241431462000382X -
Annual Review of Biochemistry Jun 2023Transcription-coupled repair (TCR), discovered as preferential nucleotide excision repair of UV-induced cyclobutane pyrimidine dimers located in transcribed mammalian... (Review)
Review
Transcription-coupled repair (TCR), discovered as preferential nucleotide excision repair of UV-induced cyclobutane pyrimidine dimers located in transcribed mammalian genes compared to those in nontranscribed regions of the genome, is defined as faster repair of the transcribed strand versus the nontranscribed strand in transcribed genes. The phenomenon, universal in model organisms including , yeast, , mice, and humans, involves a translocase that interacts with both RNA polymerase stalled at damage in the transcribed strand and nucleotide excision repair proteins to accelerate repair. , a notable exception, exhibits TCR but lacks an obvious TCR translocase. Mutations inactivating TCR genes cause increased damage-induced mutagenesis in and severe neurological and UV sensitivity syndromes in humans. To date, only TCR has been reconstituted in vitro with purified proteins. Detailed investigations of TCR using genome-wide next-generation sequencing methods, cryo-electron microscopy, single-molecule analysis, and other approaches have revealed fascinating mechanisms.
Topics: Humans; Animals; Mice; Escherichia coli; Transcription, Genetic; Cryoelectron Microscopy; DNA Repair; Receptors, Antigen, T-Cell; Mammals
PubMed: 37001137
DOI: 10.1146/annurev-biochem-041522-034232 -
Experimental Dermatology Jun 2023Ultraviolet B exposure to keratinocytes promotes carcinogenesis by inducing pyrimidine dimer lesions in DNA, suppressing the nucleotide excision repair mechanism... (Review)
Review
Ultraviolet B exposure to keratinocytes promotes carcinogenesis by inducing pyrimidine dimer lesions in DNA, suppressing the nucleotide excision repair mechanism required to fix them, inhibiting the apoptosis required for the elimination of initiated cells, and driving cellular proliferation. Certain nutraceuticals - most prominently spirulina, soy isoflavones, long-chain omega-3 fatty acids, the green tea catechin epigallocatechin gallate (EGCG) and Polypodium leucotomos extract - have been shown to oppose photocarcinogenesis, as well as sunburn and photoaging, in UVB-exposed hairless mice. It is proposed that spirulina provides protection in this regard via phycocyanobilin-mediated inhibition of Nox1-dependent NADPH oxidase; that soy isoflavones do so by opposing NF-κB transcriptional activity via oestrogen receptor-beta; that the benefit of eicosapentaenoic acid reflects decreased production of prostaglandin E2; and that EGCG counters UVB-mediated phototoxicity via inhibition of the epidermal growth factor receptor. The prospects for practical nutraceutical down-regulation of photocarcinogenesis, sunburn, and photoaging appear favourable.
Topics: Animals; Mice; Sunburn; Ultraviolet Rays; Keratinocytes; Dietary Supplements; Isoflavones; Mice, Hairless
PubMed: 36811352
DOI: 10.1111/exd.14777 -
Advances in Experimental Medicine and... 2020Sunlight, in particular UV-B radiation, is an important factor for endogenous vitamin D production as 80-90% of the required vitamin D needs to be photosynthesized in... (Review)
Review
Sunlight, in particular UV-B radiation, is an important factor for endogenous vitamin D production as 80-90% of the required vitamin D needs to be photosynthesized in the skin. The active form of vitamin D, vitamin D or calcitriol, binds to the ligand-activated transcription factor vitamin D receptor (VDR) for genomic and non-genomic effects. Recently, calcitriol and analogs have been shown to have antiproliferative effects in mouse and human BCC and SCC cell lines in vitro. As UV radiation plays a critical role in the photosynthesis of vitamin D, stringent sun protection, as recommended for xeroderma pigmentosum (XP) patients, may impact their vitamin D levels.XP is a rare autosomal recessive disorder with a worldwide prevalence of 1 in 1,000,000. XP can be divided into seven different complementation groups: XP-A to XP-G. The complementation groups correspond with the underlying gene defect. Defects in these genes lead to a defective nucleotide excision repair (NER), which is necessary to remove UV-induced DNA damage such as the UV photoproducts cyclobutane pyrimidine dimers (CPD) and 6-4 pyrimidine-pyrimidone (6-4 PP) dimer. Additionally, a variant form with a mutation in the translational polymerase η gene (PolH), also called XP variant (XPV), exists. Patients with XPV show a defect in translesion synthesis. Due to their inability to repair UV-induced lesions, XP patients exhibit an increased risk for UV-induced nonmelanoma skin cancer (NMSC) such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) as well as melanoma. Although no curative therapy for XP exists today, numerous options for the treatment and prophylaxis of skin cancer have become available.
Topics: Animals; Humans; Sunlight; Ultraviolet Rays; Vitamin D; Vitamins; Xeroderma Pigmentosum
PubMed: 32918226
DOI: 10.1007/978-3-030-46227-7_16 -
Journal of Traditional and... May 2020Skin is the largest human organ that shields the inner body from contact with xenobiotic and genotoxic agents, and in this process, the skin's cellular genome faces... (Review)
Review
Skin is the largest human organ that shields the inner body from contact with xenobiotic and genotoxic agents, and in this process, the skin's cellular genome faces continuous stress due to direct exposure to these noxious factors. Accumulation of genetic stress results in genomic alterations leading to undesirable gene or protein alteration/expression in skin cells, which eventually causes the formation of non-melanoma skin cancers (NMSCs). Ultraviolet B (UVB) radiation from sun is the most prominent factor contributing to ∼5 million skin cancer cases (which are mostly NMSCs) in the United States (US) and western countries. UVB exposure causes aberrations in a range of biochemical and molecular pathways such as: thymine dimer formation, DNA damage, oxidative stress, inflammatory responses, altered cellular signaling, which ultimately contribute to the development of NMSCs. The focus of this review is to summarize the protective and preventive potential of silymarin and/or silibinin against UVB-induced NMSC in pre-clinical skin cancer studies. Over two decades of research has shown the strong potential of silibinin, a biologically active flavonolignan (crude form Silymarin) derived from milk thistle plant, against a wide range of cancers, including NMSCs. Silibinin protects against UVB-induced thymine dimer formation and in turn promotes DNA repair and/or initiates apoptosis in damaged cells via an increase in p53 levels. Additionally, silibinin has shown strong efficacy against NMSCs via its potential to target aberrant signaling pathways, and induction of anti-inflammatory responses. Overall, completed comprehensive studies suggest the potential use of silibinin to prevent and/or manage NMSCs in humans.
PubMed: 32670818
DOI: 10.1016/j.jtcme.2020.02.003 -
Molecules (Basel, Switzerland) Sep 2022The photolyase family consists of flavoproteins with enzyme activity able to repair ultraviolet light radiation damage by photoreactivation. DNA damage by the formation... (Review)
Review
The photolyase family consists of flavoproteins with enzyme activity able to repair ultraviolet light radiation damage by photoreactivation. DNA damage by the formation of a cyclobutane pyrimidine dimer (CPD) and a pyrimidine-pyrimidone (6-4) photoproduct can lead to multiple affections such as cellular apoptosis and mutagenesis that can evolve into skin cancer. The development of integrated applications to prevent the negative effects of prolonged sunlight exposure, usually during outdoor activities, is imperative. This study presents the functions, characteristics, and types of photolyases, their therapeutic and cosmetic applications, and additionally explores some photolyase-producing microorganisms and drug delivery systems.
Topics: DNA Repair; Deoxyribodipyrimidine Photo-Lyase; Flavoproteins; Pyrimidine Dimers; Pyrimidines; Pyrimidinones; Ultraviolet Rays
PubMed: 36144740
DOI: 10.3390/molecules27185998