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Journal of Occupational and... Jan 1995Polycyclic aromatic hydrocarbon carcinogens are usually activated for DNA binding by the metabolic formation of bay region dihydrodiol epoxides with R,S,S,R... (Review)
Review
Polycyclic aromatic hydrocarbon carcinogens are usually activated for DNA binding by the metabolic formation of bay region dihydrodiol epoxides with R,S,S,R stereochemistry. Such metabolites from planar hydrocarbons reacted preferentially with the amino groups of deoxyguanosine residues, whereas those from nonplanar hydrocarbons were more efficiently trapped by DNA and reacted preferentially with the amino groups of deoxyadenosine residues, in some cases. Molecular modeling and NMR measurements indicated that the conformations of DNA adducts depend upon the hydrocarbon involved and the cis or trans opening of the epoxide ring during adduct formation. The structural characterization of carcinogen-DNA adducts and investigations of relationships between specific adducts and biological effects represent an important background that can be valuable in molecular epidemiological approaches.
Topics: DNA Adducts; Environmental Monitoring; Humans; In Vitro Techniques; Models, Molecular; Molecular Epidemiology; Molecular Structure; Polycyclic Compounds; Structure-Activity Relationship
PubMed: 7620943
DOI: 10.1097/00043764-199501000-00008 -
Mutation Research Mar 2004DNA adducts generated by carcinogenic chemicals reflects human exposure and DNA adducts are related to tumor formation. Most chemical carcinogens require activation to... (Review)
Review
DNA adducts generated by carcinogenic chemicals reflects human exposure and DNA adducts are related to tumor formation. Most chemical carcinogens require activation to reactive intermediates that bind to nucleophilic centers in proteins and nucleic acids thereby forming covalent adducts. Also, many of the chemicals considered carcinogenic for humans form covalent DNA adducts. Therefore, such DNA damage is generally considered to be causative and linked to tumor formation. In this article we have summarized the work done for many years on the role of DNA adduct formation as an indicator of their carcinogenicity. We have also addressed the important role for measurement of DNA adducts in studies with potential chemopreventive agents for which it is central to have a marker that can be measured more rapidly than changes in cancer incidence.
Topics: Animals; Biomarkers, Tumor; Carcinogens; Chemoprevention; DNA Adducts; DNA Damage; DNA, Neoplasm; Humans; Mutagenesis; Neoplasms
PubMed: 15013693
DOI: 10.1016/j.mrfmmm.2003.10.008 -
Mutation Research. Genetic Toxicology... Apr 2020Diet is a major source of human exposure to polycyclic aromatic hydrocarbons (PAHs), of which benzo[a]pyrene (BaP) is the most commonly studied and measured. BaP has...
Diet is a major source of human exposure to polycyclic aromatic hydrocarbons (PAHs), of which benzo[a]pyrene (BaP) is the most commonly studied and measured. BaP has been considered to exert its genotoxic effects after metabolic activation by cytochrome P450 (CYP) enzymes whose activity can be modulated by cytochrome P450 oxidoreductase (POR), the electron donor to CYP enzymes. Previous studies showed that BaP-DNA adduct formation was greater in the livers of Hepatic Reductase Null (HRN) mice, in which POR is deleted specifically in hepatocytes, than in wild-type (WT) mice. In the present study we used human hepatoma HepG2 cells carrying a knockout (KO) in the POR gene as a human in vitro model that can mimic the HRN mouse model. Treatment to BaP for up to 48 h caused similar cytotoxicity in POR KO and WT HepG2 cells. However, levels of BaP activation (i.e. BaP-7,8-dihydrodiol formation) were higher in POR KO HepG2 cells than in WT HepG2 cells after 48 h. This also resulted in substantially higher BaP-DNA adduct formation in POR KO HepG2 cells indicating that BaP metabolism is delayed in POR KO HepG2 cells thereby prolonging the effective exposure of cells to unmetabolized BaP. As was seen in the HRN mouse model, these results suggest that cytochrome b, another component of the mixed-function oxidase system, which can also serve as electron donor to CYP enzymes along with NADH:cytochrome b redutase, contributes to the bioactivation of BaP in POR KO HepG2 cells. Collectively, these findings indicate that CYPs play a more important role in BaP detoxication as opposed to activation.
Topics: Benzo(a)pyrene; Carcinogens; Cell Survival; Cytochrome P-450 Enzyme System; DNA Adducts; DNA Damage; Dose-Response Relationship, Drug; Gene Expression; Gene Knockout Techniques; Hep G2 Cells; Humans
PubMed: 32265041
DOI: 10.1016/j.mrgentox.2020.503162 -
Bioorganic & Medicinal Chemistry Letters Mar 2021Current techniques for the identification of DNA adduct-inducing and DNA interstrand crosslinking agents include electrophoretic crosslinking assays, electrophoretic gel...
Current techniques for the identification of DNA adduct-inducing and DNA interstrand crosslinking agents include electrophoretic crosslinking assays, electrophoretic gel shift assays, DNA and RNA stop assays, mass spectrometry-based methods and P-post-labelling. While these assays provide considerable insight into the site and stability of the interaction, they are relatively expensive, time-consuming and sometimes rely on the use of radioactively-labelled components, and thus are ill-suited to screening large numbers of compounds. A novel medium throughput assay was developed to overcome these limitations and was based on the attachment of a biotin-tagged double stranded (ds) oligonucleotide to Corning DNA-Bind plates. We aimed to detect anthracycline and anthracenedione DNA adducts which form by initial non-covalent intercalation with duplex DNA, and subsequent covalent adduct formation which is mediated by formaldehyde. Following drug treatment, DNA samples were subjected to a denaturation step, washing and then measurement by fluorescence to detect remaining drug-DNA species using streptavidin-europium. This dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA) is a time-resolved fluorescence intensity assay where the fluorescence signal arises only from stabilised drug-DNA complexes. We applied this new methodology to the identification of anthracycline-like compounds with the ability to functionally crosslink double-strand oligonucleotides. The entire procedure can be performed by robotics, requiring low volumes of compounds and reagents, thereby reducing costs and enabling multiple compounds to be assessed on a single microtitre plate.
Topics: Automation; Cross-Linking Reagents; DNA Adducts; Dose-Response Relationship, Drug; Drug Development; Molecular Structure; Structure-Activity Relationship
PubMed: 33486050
DOI: 10.1016/j.bmcl.2021.127813 -
The Analyst Oct 2016Exposure to chemical pollutants and pharmaceuticals may cause health issues caused by metabolite-related toxicity. This paper reports a new microfluidic electrochemical...
Exposure to chemical pollutants and pharmaceuticals may cause health issues caused by metabolite-related toxicity. This paper reports a new microfluidic electrochemical sensor array with the ability to simultaneously detect common types of DNA damage including oxidation and nucleobase adduct formation. Sensors in the 8-electrode screen-printed carbon array were coated with thin films of metallopolymers osmium or ruthenium bipyridyl-poly(vinylpyridine) chloride (OsPVP, RuPVP) along with DNA and metabolic enzymes by layer-by-layer electrostatic assembly. After a reaction step in which test chemicals and other necessary reagents flow over the array, OsPVP selectively detects oxidized guanines on the DNA strands, and RuPVP detects DNA adduction by metabolites on nucleobases. We demonstrate array performance for test chemicals including 17β-estradiol (E), its metabolites 4-hydroxyestradiol (4-OHE), 2-hydroxyestradiol (2-OHE), catechol, 2-nitrosotoluene (2-NO-T), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and 2-acetylaminofluorene (2-AAF). Results revealed DNA-adduct and oxidation damage in a single run to provide a metabolic-genotoxic chemistry screen. The array measures damage directly in unhydrolyzed DNA, and is less expensive, faster, and simpler than conventional methods to detect DNA damage. The detection limit for oxidation is 672 8-oxodG per 10 bases. Each sensor requires only 22 ng of DNA, so the mass detection limit is 15 pg (∼10 pmol) 8-oxodG.
Topics: DNA; DNA Adducts; DNA Damage; Microfluidic Analytical Techniques; Oxidation-Reduction
PubMed: 27517117
DOI: 10.1039/c6an01237j -
International Journal of Cancer Oct 20053-Nitrobenzanthrone (3-NBA) is an environmental pollutant and suspected human carcinogen found in emissions from diesel and gasoline engines and on the surface of...
3-Nitrobenzanthrone (3-NBA) is an environmental pollutant and suspected human carcinogen found in emissions from diesel and gasoline engines and on the surface of ambient air particulate matter; human exposure to 3-NBA is likely to occur primarily via the respiratory tract. In our study female Sprague Dawley rats were treated by intratracheal instillation with a single dose of 0.2 or 2 mg/kg body weight of 3-NBA. Using the butanol enrichment version of the (32)P-postlabeling method, DNA adduct formation by 3-NBA 48 hr after intratracheal administration in different organs (lung, pancreas, kidney, urinary bladder, heart, small intestine and liver) and in blood was investigated. The same adduct pattern consisting of up to 5 DNA adduct spots was detected by thin layer chromatography in all tissues and blood and at both doses. Highest total adduct levels were found in lung and pancreas (350 +/- 139 and 620 +/- 370 adducts per 10(8) nucleotides for the high dose and 39 +/- 18 and 55 +/- 34 adducts per 10(8) nucleotides for the low dose, respectively) followed by kidney, urinary bladder, heart, small intestine and liver. Adduct levels were dose-dependent in all organs (approximately 10-fold difference between doses). It was demonstrated by high performance liquid chromatography (HPLC) that all 5 3-NBA-derived DNA adducts formed in rats after intratracheal instillation are identical to those formed by other routes of application and are, as previously shown, formed from reductive metabolites bound to purine bases. Although total adduct levels in the blood were much lower (41 +/- 27 and 9.5 +/- 1.9 adducts per 10(8) nucleotides for the high and low dose, respectively) than those found in the lung, they were related to dose and to the levels found in lung. These results show that uptake of 3-NBA by the lung induces high levels of specific DNA adducts in several organs of the rat and an identical adduct pattern in DNA from blood. Therefore, 3-NBA-DNA adducts present in the blood are useful biomarkers for exposure to 3-NBA and may help to assess the effective biological dose in humans exposed to it.
Topics: Animals; Benz(a)Anthracenes; DNA Adducts; Environmental Pollutants; Female; Instillation, Drug; Intubation, Intratracheal; Lung; Pancreas; Rats; Rats, Sprague-Dawley; Tissue Distribution
PubMed: 15856450
DOI: 10.1002/ijc.21095 -
Journal of Chromatography. B,... Oct 2002It is undisputed that DNA adduct formation is one of the key processes in early carcinogenesis. Therefore, analysis of DNA adduct levels may be one of the best tools... (Review)
Review
It is undisputed that DNA adduct formation is one of the key processes in early carcinogenesis. Therefore, analysis of DNA adduct levels may be one of the best tools available to characterize exposure to complex mixtures of genotoxic chemicals as occurring in different environmental and occupational exposure settings. However, from an analytical point of view the detection and quantification of DNA adducts is a challenging enterprise as extremely high sensitivity and selectivity are required. The entire spectrum of chromatographic techniques, including thin-layer chromatography (TLC), gas and liquid chromatography as well as capillary electrophoresis has been used in combination with different detection systems, all with their own specific characteristics. Among the various combinations of techniques, the TLC-(32)P-postlabeling combination appears to meet best with criteria of sensitivity and requirements of minimal amounts of material. Recent developments in the application of capillary electrophoresis in combination with either immunochemical or mass spectrometric detection techniques may offer new and promising approaches, with higher selectivity as compared to TLC-(32)P postlabeling. The applicability of these new techniques in biomonitoring studies aiming at the exposure and risk assessment of low and chronic exposures remains to be determined. In this paper we compare and discuss the advantages and limitations of different techniques used in DNA adduct analysis, with specific emphasis on those adducts formed by the polycyclic aromatic hydrocarbons and heterocyclic aromatic amines.
Topics: DNA Adducts; Environmental Exposure; Humans; Occupational Exposure
PubMed: 12376139
DOI: 10.1016/s0378-4347(01)00543-6 -
Carcinogenesis May 2014The estrogen analog tamoxifen (TAM), used for adjuvant therapy of breast cancer, induces endometrial and uterine tumors in breast cancer patients. Proliferation stimulus...
The estrogen analog tamoxifen (TAM), used for adjuvant therapy of breast cancer, induces endometrial and uterine tumors in breast cancer patients. Proliferation stimulus of the uterine endometrium is likely involved in tumor induction, but genotoxicity may also play a role. Formation of TAM-DNA adducts in human tissues has been reported but remains controversial. To address this issue, we examined TAM-DNA adducts in uteri from two species of monkeys, Erythrocebus patas (patas) and Macaca fascicularis (macaque), and in human endometrium and myometrium. Monkeys were given 3-4 months of chronic TAM dosing scaled to be equivalent to the daily human dose. In the uteri, livers and brains from the patas (n = 3), and endometrium from the macaques (n = 4), TAM-DNA adducts were measurable by TAM-DNA chemiluminescence immunoassay. Average TAM-DNA adduct values for the patas uteri (23 adducts/10(8) nucleotides) were similar to those found in endometrium of the macaques (19 adducts/10(8) nucleotides). Endometrium of macaques exposed to both TAM and low-dose estradiol (n = 5) averaged 34 adducts/10(8) nucleotides. To examine TAM-DNA persistence in the patas, females (n = 3) were exposed to TAM for 3 months and to no drug for an additional month, resulting in low or non-detectable TAM-DNA in livers and uteri. Human endometrial and myometrial samples from women receiving (n = 8) and not receiving (n = 8) TAM therapy were also evaluated. Women receiving TAM therapy averaged 10.3 TAM-DNA adducts/10(8) nucleotides, whereas unexposed women showed no detectable TAM-DNA. The data indicate that genotoxicity, in addition to estrogen agonist effects, may contribute to TAM-induced human endometrial cancer.
Topics: Animals; DNA; DNA Adducts; Endometrium; Erythrocebus patas; Female; Humans; Myometrium; Tamoxifen; Uterus
PubMed: 24501327
DOI: 10.1093/carcin/bgu029 -
IET Nanobiotechnology Apr 2015The optical and physico-chemical properties of gold nanoparticles (AuNPs) have prompted new and improved approaches which have greatly evolved the fields of biosensing...
The optical and physico-chemical properties of gold nanoparticles (AuNPs) have prompted new and improved approaches which have greatly evolved the fields of biosensing and molecular detection. In this study, the authors took advantage of AuNPs' ease of modification and functionalised it with selected DNA aptamers using a salt aging method to produce gold-aptamer nanoprobes. After characterisation, these nanoprobes were subsequently used for biomolecular detection of glycidamide (GA)-guanine (Gua) adducts generated in vitro. The results are based on differences in nanoprobe stabilisation against salt-induced aggregation, similar to the non-cross-linking method developed by Baptista for discrimination of specific sequences. Alkylated Guas were efficiently discriminated from deoxyguanosine and GA in solution. Despite this, a clear identification of DNA adducts derived from genomic DNA alkylation has proven to be a more challenging task.
Topics: Aptamers, Nucleotide; Colorimetry; DNA Adducts; Epoxy Compounds; Gold; Guanine; Metal Nanoparticles; Molecular Probe Techniques; Sequence Analysis, DNA
PubMed: 25829175
DOI: 10.1049/iet-nbt.2014.0007 -
The Science of the Total Environment Jan 2008The genotoxic effects of air pollutant exposures have been studied in people living and working in Map Ta Phut, Rayong province, Thailand, a site where is located the...
The genotoxic effects of air pollutant exposures have been studied in people living and working in Map Ta Phut, Rayong province, Thailand, a site where is located the Map Ta Phut Industrial Estate (MIE) one of the largest steel, refinery and petrochemical complex in the South-Eastern Asia. This was done by the conduction of a transversal study aimed to compare the prevalence of bulky DNA adducts in groups of subjects experiencing various degree of air pollution. DNA adduct analysis was performed in the leukocytes of 201 volunteers by the (32)P-postlabelling assay: 79 were workers in the MIE complex, including 24 refinery workers, 40 steel workers and 15 tinplate workers, 72 were people residing downwind in the MIE area and 50 were residents in a control district of the same Rayong province but without industrial exposures. The groups of workers were analyzed separately to evaluate if DNA adduct formation differs by the type of industry. The levels of bulky DNA adducts were 1.17+/-0.17 (SE) adducts/10(8) nucleotides in refinery workers, 1.19+/-0.19 (SE) in steel workers, 0.87+/-0.17 (SE) in tinplate workers, 0.85+/-0.07 (SE) in MIE residents and 0.53+/-0.05 (SE) in district controls. No effects of smoking habits on DNA adducts was found. The multivariate regression analysis shows that the levels of DNA adducts were significantly increased among the individuals living near the MIE industrial complex in respect to those resident in a control district (p<0.05). In the groups of occupationally exposed workers, the highest levels of DNA adducts were found among the workers experiencing an occupational exposure to polycyclic aromatic hydrocarbons, e.g. the steel factory and refinery workers. When we have evaluated if the levels of DNA adducts of the PAH exposed workers were different from those of the MIE residents, a statistical significantly difference was found (p<0.05). Our present study indicates that people living near point sources of industrial air pollution can experiment an excess of DNA adduct formation. The emissions from the MIE complex are the main source of air pollution in this area and can be the cause of such increment in the levels of DNA damage.
Topics: Adult; Air Pollutants, Occupational; Air Pollution; DNA Adducts; Extraction and Processing Industry; Female; Humans; Inhalation Exposure; Leukocytes; Male; Occupational Exposure; Thailand
PubMed: 17935758
DOI: 10.1016/j.scitotenv.2007.09.012