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Environmental Health Perspectives May 1996Human exposure to chemical compounds, often termed xenobiotics, has been linked to a number of enhanced incidences of various neoplasias. A majority of these enter the...
Human exposure to chemical compounds, often termed xenobiotics, has been linked to a number of enhanced incidences of various neoplasias. A majority of these enter the human body through inhalation. Most xenobiotics are metabolized in the body to more hydrophilic metabolites before excretion in the urine and bile. During this process, promutagens and procarcinogens could be activated and could interact with proteins as well as DNA to form adducts. DNA adducts formed by chemical carcinogens can, therefore, be used as biomarkers of exposure and other host factors. This study that DNA adduct analysis can be performed on cells from human nasal mucosa. Using the nasal lavage procedure performed on 20 healthy volunteers, 5 x 10(5) to 5 x 10(6) cells were obtained from which 5 to 40 micrograms DNA was isolated. DNA adducts were analyzed by the 32-P-postlabeling assay. The DNA adduct levels ranged between 1.4 and 6 adducts/10(8) nucleotides. In addition to its simplicity, the nasal lavage procedure is an inexpensive, noninvasive procedure that requires no anesthetics or special equipment. Moreover, the cells obtained are the first to come in contact with air pollutants. DNA adduct analysis from human nose mucosa cells could therefore be used to develop a technique suitable for the assessment of exposure to chemical carcinogens through inhalation.
Topics: Adult; Carcinogens, Environmental; DNA; DNA Adducts; Humans; Middle Aged; Mutagens; Nasal Mucosa; Therapeutic Irrigation
PubMed: 8781366
DOI: 10.1289/ehp.96104s3471 -
Biochemical and Biophysical Research... Jul 2012Acetaldehyde (AA) derived from alcoholic beverages is a confirmed carcinogen for esophageal and head and neck cancers. AA forms various DNA adducts and is thought to...
Acetaldehyde (AA) derived from alcoholic beverages is a confirmed carcinogen for esophageal and head and neck cancers. AA forms various DNA adducts and is thought to play a crucial role in carcinogenesis. Transient DNA adducts are usually repaired, but the stability of AA-derived DNA adducts has not been elucidated. We investigated the stability of N(2)-ethylidene-2'-deoxyguanosine (N(2)-ethylidene-dG), a major AA-derived DNA adduct, in cultured cells. First, to determine the optimal concentration of AA for detecting N(2)-ethylidene-dG in cell culture, a dose-response study was performed using HL60 cells of the human promyelocytic leukemia cell line. An AA concentration ≥ 0.01% (1.8 mM) was required to detect N(2)-ethylidene-dG in vitro. We next examined the stability of N(2)-ethylidene-dG. After a 1 or 2h exposure to 0.01% of AA in a tightly sealed bottle, N(2)-ethylidene-dG content was measured by sensitive liquid chromatography tandem mass spectrometry immediately, 24h, and 48 h after exposure. After the 1h exposure, the mean (± SD) N(2)-ethylidene-dG contents were 12.1 ± 1.28, 8.20 ± 0.64, and 6.70 ± 0.52 adducts per 10(7) bases at each postexposure time. After the 2h exposure, N(2)-ethylidene-dG content increased to 21.4 ± 7.50, 10.5 ± 3.61, and 9.83 ± 3.90 adducts per 10(7) bases at each postexposure time. The half-life of this adduct was calculated as ∼35 h in independent experiments. These results indicate that AA exposure from daily alcohol consumption may cause DNA damage and may increase the risk of alcohol-related carcinogenesis.
Topics: Acetaldehyde; Carcinogens; Cell Culture Techniques; Cell Transformation, Neoplastic; DNA Adducts; Deoxyguanosine; HL-60 Cells; Half-Life; Humans
PubMed: 22683642
DOI: 10.1016/j.bbrc.2012.05.158 -
Chemical Research in Toxicology Mar 2020Arylamine modification of guanine base at the G position in the I sequence (-GGCGCC-) causes a frameshift mutation. Polymerase and F NMR studies have shown that the next...
Arylamine modification of guanine base at the G position in the I sequence (-GGCGCC-) causes a frameshift mutation. Polymerase and F NMR studies have shown that the next flanking base at the 3' position to the G adduct modulates the mutational outcome because of its different conformations. Here, we have studied the interaction of the 16-mer I sequence (5'-CTCTCGGCCXATCAC-3') (G = -acetyl-2-aminofluorene (AAF)-dG and X is either C or T) with [Ru(phen)(dppz)] (phen = 1,10-phenanthroline and dppz = dipyrido[3,2-:2',3'-]phenazine). Interaction studies between isomers of Ru(II) and two oligonucleotide models, viz., (a) full duplex, and (b) slipped mutagenic intermediate (SMI), have been carried out. Luminescence studies reveal that the sensitivity of Ru(II) with an adduct increases 2- to 3-fold compared to that of control in full duplex. In SMI, the sensitivity of Ru(II) varies with the next flanking base and in the order of -GCC > -GCT. Microscale thermophoretic data reveal that in full duplex Λ-Ru binds to -GCT- by 13- and 4-fold stronger than its control and -GCC-, respectively. In SMI, Δ-Ru binds to -GCC- (41% stacked () conformer) by 3-fold while -GCT- (86% major groove () conformer) weakens the binding of Λ-Ru by 250-fold compared to the control. The results presented here reveal that the binding of Ru(II) not only depends on conformations of the AAF-dG adduct but also is isomer-centric and might be helpful in determining the conformational heterogeneity of other covalent aryl/heterocyclic amine-DNA adducts.
Topics: Amines; DNA Adducts; Frameshift Mutation; Models, Molecular; Molecular Conformation; Organometallic Compounds
PubMed: 32039589
DOI: 10.1021/acs.chemrestox.9b00453 -
Cancer Research Oct 1999Tamoxifen (TAM), a nonsteroidal antiestrogen used as a chemotherapeutic and chemopreventive agent for breast cancer, induces liver tumors in rodents and covalent DNA... (Comparative Study)
Comparative Study
Tamoxifen (TAM), a nonsteroidal antiestrogen used as a chemotherapeutic and chemopreventive agent for breast cancer, induces liver tumors in rodents and covalent DNA adduct formation in hepatic DNA. Here, we report the development and validation of highly sensitive and specific immunoassays for the determination of TAM-DNA adducts. Rabbits were immunized with calf thymus DNA, chemically modified with alpha-acetoxytamoxifen to 2.4 adducts per 100 nucleotides, and the resulting antisera were characterized by competitive dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) and chemiluminescence immunoassay (CIA). Compared with DELFIA, the CIA has a much lower background and a 20-fold increase in sensitivity. For the immunogen TAM-DNA, 50% inhibition was at 2.0 +/- 0.11 (mean +/- SE, n = 18) fmol of (E)-alpha-(N2-deoxyguanosinyl)tamoxifen (TAM-dG) adduct in TAM-DNA by DELFIA. For TAM-DNA modified to 4.8 adducts in 10(6) nucleotides, 50% inhibition was at 20.6 +/- 6.6 (mean +/- SE, n = 8) fmol of TAM-dG in TAM-DNA by DELFIA and at 0.92 +/- 0.11 (mean +/- SE, n = 10) fmol of TAM-dG in TAM-DNA by CIA. No inhibition was observed in either assay with up to 20 microg (62.5 nmol of nucleotides) of unmodified DNA. The individual adducts TAM-dG and (Z)-alpha-(N2-deoxyguanosinyl)tamoxifen and the individual compounds TAM and 4-OH-TAM gave DELFIA 50% inhibitions at 828, 2229, 5440, and 8250 fmol, respectively. For assay validation, TAM-dG levels were determined by DELFIA, CIA, and 32P-postlabeling in TAM-DNA samples modified in vitro to different levels, and comparable values were obtained in all three assays. Further validation was obtained in vivo in rat liver. DNA adducts of TAM were measurable in rat liver 24 h after a single i.p. dose of 45 mg TAM/kg body weight and after daily p.o. dosing for 7 days with 5.0, 10.0, and 20.0 mg TAM/kg body weight. In addition, TAM-DNA adducts disappeared slowly over 21 days in rats on a control diet that were first given p.o. TAM at 45 mg/kg/day for 4 days. In the rat experiments, TAM-DNA adduct levels determined by CIA compared well with those determined by 32P-postlabeling, although the CIA gave an underestimation at the highest doses. For rat liver samples, the detection limit by CIA was 3 adducts per 10(9) nucleotides (0.2 fmol of adducts per 20 microg of DNA).
Topics: Animals; Antibodies; DNA; DNA Adducts; Female; Fluorescent Antibody Technique; Immunoassay; Kinetics; Liver; Luminescent Measurements; Phosphorus Radioisotopes; Rabbits; Radioisotope Dilution Technique; Rats; Rats, Inbred F344; Reproducibility of Results; Tamoxifen
PubMed: 10519392
DOI: No ID Found -
Chemical Research in Toxicology Jul 2014The conformational preference of the O6-benzyl-guanine (BzG) adduct was computationally examined using nucleoside, nucleotide, and DNA models, which provided critical...
The conformational preference of the O6-benzyl-guanine (BzG) adduct was computationally examined using nucleoside, nucleotide, and DNA models, which provided critical information about the potential mutagenic consequences and toxicity of the BzG adduct in our cells. Substantial conformational flexibility of the BzG moiety, including rotation of the bulky group with respect to the base and the internal conformation of the bulk moiety, is seen in the nucleoside and nucleotide models. This large conformational flexibility suggests the conformation adopted by BzG is dependent on the local environment of the BzG adduct. Upon incorporation of the adduct into the DNA helix, the BzG conformational flexibility is maintained. The range of BzG conformations adopted in DNA likely arises due to a combination of the long and flexible (-CH2-) linker, the small adduct size, and the lack of discrete interactions between the bulky moiety and G. Because of the conformational flexibility of the adduct, many DNA conformations are observed for BzG adducted DNA, including those not previously reported in the literature, and thus, a modified nomenclature for adducted DNA conformations is presented. Furthermore, the preferred conformation of BzG adducted DNA is greatly dependent on a number of factors, including the pairing nucleotide, the discrete interactions in the helix, and the solvation of the benzyl moiety. These factors in turn lead to a complicated mutagenic and toxic profile that may invoke pairing with natural C, mispairs, or deletion mutations, which is supported by previously reported experimental biochemical studies. Despite this complex mutagenic profile, pairing with C leads to the most stable helical structure, which is the first combined structural and energetic explanation for experimental studies reporting a higher rate of C incorporation than any other nucleobase upon BzG replication.
Topics: DNA Adducts; Guanine; Molecular Docking Simulation; Nucleic Acid Conformation
PubMed: 24941023
DOI: 10.1021/tx500178x -
Chemical Research in Toxicology Mar 1996DNA adduct formation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was investigated in cynomolgus monkeys. The pattern and distribution of DNA adducts examined by...
DNA adduct formation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was investigated in cynomolgus monkeys. The pattern and distribution of DNA adducts examined by 32P-postlabeling were similar in all tissues 24 h after a single oral dose of IQ (20 mg/kg). The highest DNA adduct levels were found in the liver (3.67-11.19 adducts per 10(7) bases), followed by kidney (0.53-1.16 adducts per 10(7) bases), with comparable adduct levels detected in colon, heart, and pancreas (0.15-0.40 adducts per 10(7) bases). Two 2'-deoxyguanosine (dG) adducts accounted for approximately 90% of the observed lesions in all tissues. N-(Deoxyguanosin-8-yl)-2-amino-3-methylimidazo[4,5-f]quinoline (dG-C8-IQ) was the major adduct and accounted for approximately 50-80% of the adducts, followed by 5-(deoxyguanosin-N2-yl)-amino-3-methylimidazo[4,5-f]quinoline (dG-N2-IQ) which accounted for 20-40% of the adducts. DNA adduct formation was also investigated in animals undergoing carcinogen bioassay with IQ administered at 10 or 20 mg/kg, 5 days per week for up to 9.2 years. In chronically treated animals, the DNA adduct levels in pancreas, kidney, and heart increased on average by 40- to 90-fold over those observed in animals given a single dose, while only 3- to 10-fold increases in adducts were observed in colon and liver. A sharp increase in the contribution of dG-N2-IQ to total DNA adducts occurred in all slowly dividing tissues during chronic treatment, and dG-N2-IQ became the predominant lesion. There was no preferential accumulation of dG-N2-IQ in the colon, a tissue with a high rate of cell division, and dG-C8-IQ remained the predominant lesion. These findings point to a preferential removal of the dG-C8-IQ adduct by enzyme repair system(s) in slowly dividing tissues. The respective roles of dG-N2-IQ and dG-C8-IQ, and the involvement of adduct repair in the potent hepatocarcinogenicity of IQ, merit further investigation.
Topics: Animals; Carcinogenicity Tests; DNA Adducts; Female; Guanine; Macaca fascicularis; Male; Mutagens; Quinolines
PubMed: 8839042
DOI: 10.1021/tx950132j -
Cancer Letters Jul 2007Ellipticine induces formation of two DNA adducts in leukemia HL-60 and CCRF-CEM cells, identical with deoxyguanosine adducts generated by ellipticine metabolites...
Ellipticine induces formation of two DNA adducts in leukemia HL-60 and CCRF-CEM cells, identical with deoxyguanosine adducts generated by ellipticine metabolites 13-hydroxyellipticine and 12-hydroxyellipticine in vitro and in vivo. The ellipticine cytotoxicity to HL-60 (IC(50)=0.64microM) and CCRF-CEM cells (IC(50)=4.7microM) correlates with levels of DNA adducts. The different expressions of enzymes activating ellipticine in cells explain this finding. While cytochrome P450 1A1 and cyclooxygenase-1 are expressed in both cells, HL-60 cells express also high levels of another activator, myeloperoxidase. The results suggest the adduct formation as a new mode of antitumor action of ellipticine for leukemia.
Topics: Antineoplastic Agents; Cell Line, Tumor; DNA Adducts; Ellipticines; Humans; Leukemia
PubMed: 17306925
DOI: 10.1016/j.canlet.2006.12.037 -
Chemical Research in Toxicology Feb 1997
Review
Topics: Animals; Carcinogens; DNA Adducts; Humans; Magnetic Resonance Spectroscopy; Polycyclic Aromatic Hydrocarbons; Stereoisomerism
PubMed: 9049424
DOI: 10.1021/tx9601418 -
Chemical Society Reviews Nov 2015Exogenous and endogenous sources of chemical species can react, directly or after metabolic activation, with DNA to yield DNA adducts. If not repaired, DNA adducts may... (Review)
Review
Exogenous and endogenous sources of chemical species can react, directly or after metabolic activation, with DNA to yield DNA adducts. If not repaired, DNA adducts may compromise cellular functions by blocking DNA replication and/or inducing mutations. Unambiguous identification of the structures and accurate measurements of the levels of DNA adducts in cellular and tissue DNA constitute the first and important step towards understanding the biological consequences of these adducts. The advances in mass spectrometry (MS) instrumentation in the past 2-3 decades have rendered MS an important tool for structure elucidation, quantification, and revelation of the biological consequences of DNA adducts. In this review, we summarized the development of MS techniques on these fronts for DNA adduct analysis. We placed our emphasis of discussion on sample preparation, the combination of MS with gas chromatography- or liquid chromatography (LC)-based separation techniques for the quantitative measurement of DNA adducts, and the use of LC-MS along with molecular biology tools for understanding the human health consequences of DNA adducts. The applications of mass spectrometry-based DNA adduct analysis for predicting the therapeutic outcome of anti-cancer agents, for monitoring the human exposure to endogenous and environmental genotoxic agents, and for DNA repair studies were also discussed.
Topics: Chromatography, Liquid; DNA Adducts; Spectrometry, Mass, Electrospray Ionization
PubMed: 26204249
DOI: 10.1039/c5cs00316d -
Mutation Research May 1998The methodology applied for DNA adducts in humans has become more reliable in recent years, allowing to detect even background carcinogenic adduct levels in... (Review)
Review
The methodology applied for DNA adducts in humans has become more reliable in recent years, allowing to detect even background carcinogenic adduct levels in environmentally exposed persons. Particularly, combinations of the various methods now allow the elucidation of specific adduct structures with detection limits of 1 adduct in 108 unmodified nucleotides or even lower. The quantification of polycyclic aromatic hydrocarbon-DNA (PAH-DNA) adducts in human tissues and cells has been achieved with a number of highly sensitive techniques: immunoassays and immunocytochemistry using polyclonal or monoclonal antisera specific for DNA adducts or modified DNA, the assay, and adduct identification using physicochemical instrumentation. The results summarized in this review show that PAH-DNA adducts have been detected in a variety of human tissues, including target organs of PAH- and tobacco-associated cancers. Although dosimetry has not always been precise, a large number of data now clearly show that lowering exposure to carcinogenic PAH results in decreasing PAH-DNA adduct levels. In most studies, however, bulk DNA of a certain tissue or cell type has been examined, and there were relatively few studies in which mutations as a consequence of DNA damage at specific genes have been investigated. Promising as these biomarker studies seem for epidemiology and health surveillance, future biomonitoring and molecular epidemiological studies should be directed to combine several endpoint measurements: i.e., adduct formation (preferably at specific sites), mutational spectra in cancer-relevant genes, and genetic markers of (cancer) susceptibility in a number of cancer-predisposing genes.
Topics: Animals; Biomarkers; DNA Adducts; Environmental Exposure; Humans; Neoplasms; Neoplasms, Experimental; Polycyclic Aromatic Hydrocarbons; Risk Assessment
PubMed: 9685648
DOI: 10.1016/s0027-5107(98)00065-7