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Archives of Toxicology Apr 2018Benzo[a]pyrene (BaP) is an environmental pollutant that, based on evidence largely from in vitro studies, exerts its genotoxic effects after metabolic activation by...
Cytochrome b impacts on cytochrome P450-mediated metabolism of benzo[a]pyrene and its DNA adduct formation: studies in hepatic cytochrome b /P450 reductase null (HBRN) mice.
Benzo[a]pyrene (BaP) is an environmental pollutant that, based on evidence largely from in vitro studies, exerts its genotoxic effects after metabolic activation by cytochrome P450s. In the present study, Hepatic Reductase Null (HRN) and Hepatic Cytochrome b /P450 Reductase Null (HBRN) mice have been used to study the role of P450s in the metabolic activation of BaP in vivo. In HRN mice, cytochrome P450 oxidoreductase (POR), the electron donor to P450, is deleted specifically in hepatocytes. In HBRN mice the microsomal haemoprotein cytochrome b , which can also act as an electron donor from cytochrome b reductase to P450s, is also deleted in the liver. Wild-type (WT), HRN and HBRN mice were treated by i.p. injection with 125 mg/kg body weight BaP for 24 h. Hepatic microsomal fractions were isolated from BaP-treated and untreated mice. In vitro incubations carried out with BaP-pretreated microsomal fractions, BaP and DNA resulted in significantly higher BaP-DNA adduct formation with WT microsomal fractions compared to those from HRN or HBRN mice. Adduct formation (i.e. 10-(deoxyguanosin-N-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP [dG-N-BPDE]) correlated with observed CYP1A activity and metabolite formation (i.e. BaP-7,8-dihydrodiol) when NADPH or NADH was used as enzymatic cofactors. BaP-DNA adduct levels (i.e. dG-N-BPDE) in vivo were significantly higher (~ sevenfold) in liver of HRN mice than WT mice while no significant difference in adduct formation was observed in liver between HBRN and WT mice. Our results demonstrate that POR and cytochrome b both modulate P450-mediated activation of BaP in vitro. However, hepatic P450 enzymes in vivo appear to be more important for BaP detoxification than its activation.
Topics: Animals; Benzo(a)pyrene; Cytochrome-B(5) Reductase; DNA Adducts; Hepatocytes; Mice; Mice, Knockout; Microsomes, Liver; NADPH-Ferrihemoprotein Reductase
PubMed: 29368147
DOI: 10.1007/s00204-018-2162-7 -
Journal of Nanobiotechnology Sep 2022Despite many nano-based strategies devoted to delivering cisplatin for tumor therapy, its clinical benefits are compromised by poor tissue penetration and limited DNA...
Despite many nano-based strategies devoted to delivering cisplatin for tumor therapy, its clinical benefits are compromised by poor tissue penetration and limited DNA adducts formation of the drug. Herein, a cisplatin loading nanomotor based janus structured Ag-polymer is developed for cisplatin delivery of deeper tissue and increased DNA adducts formation. The nanomotor displayed a self-propelled tumor penetration fueled by hydrogen peroxide (HO) in tumor tissues, which is catalytically decomposed into a large amount of oxygen bubbles by Ag nanoparticles (NPs). Notably, cisplatin could elevate the intracellular HO level through cascade reactions, further promote the degradation of Ag NPs accompanied with the Ag release, which could downregulate intracellular Cl through the formation of AgCl precipitate, thereby enhancing cisplatin dechlorination and Pt-DNA formation. Moreover, polymer can also inhibit the activity of ALKBH2 (a Fe-dependent DNA repair enzyme) by chelating intracellular Fe to increase the proportion of irreparable Pt-DNA cross-links. It is found that deep tissue penetration, as well as the increased formation and maintenance of Pt-DNA adducts induced by the nanomotor afford 80% of tumor growth inhibition with negligible toxicity. This work provides an important perspective of resolving chemotherapeutic barriers for boosting cisplatin therapy.
Topics: Antineoplastic Agents; Cisplatin; DNA; DNA Adducts; Humans; Hydrogen Peroxide; Metal Nanoparticles; Neoplasms; Oxygen; Polymers; Silver
PubMed: 36175999
DOI: 10.1186/s12951-022-01622-3 -
Experimental Oncology Mar 2015In recent years, the new direction such as identification of informative circulating markers reflecting molecular genetic changes in the DNA of tumor cells was actively... (Review)
Review
In recent years, the new direction such as identification of informative circulating markers reflecting molecular genetic changes in the DNA of tumor cells was actively developed. Smoking-related DNA adducts are very promising research area, since they indicate high pathogenetic importance in the lung carcinogenesis and can be identified in biological samples with high accuracy and reliability using highly sensitive mass spectrometry methods (TOF/TOF, TOF/MS, MS/MS). The appearance of DNA adducts in blood or tissues is the result of the interaction of carcinogenic factors, such as tobacco constituents, and the body reaction which is determined by individual characteristics of metabolic and repair systems. So, DNA adducts may be considered as a cumulative mirror of heterogeneous response of different individuals to smoking carcinogens, which finally could determine the risk for lung cancer. This review is devoted to analysis of the role of DNA adducts in lung carcinogenesis in order to demonstrate their usefulness as cancer associated markers. Currently, there are some serious limitations impeding the widespread use of DNA adducts as cancer biomarkers, due to failure of standardization of mass spectrometry analysis in order to correctly measure the adduct level in each individual. However, it is known that all DNA adducts are immunogenic, their accumulation over some threshold concentration leads to the appearance of long-living autoantibodies. Thus, detection of an informative pattern of autoantibodies against DNA adducts using innovative multiplex ELISA immunoassay may be a promising approach to find lung cancer at an early stage in high-risk groups (smokers, manufacturing workers, urban dwellers).
Topics: Animals; Biomarkers, Tumor; DNA Adducts; Enzyme-Linked Immunosorbent Assay; Humans; Lung; Lung Neoplasms; Mass Spectrometry; Smoking
PubMed: 25804224
DOI: No ID Found -
Biochemistry Nov 2003DNA damage recognition of nucleotide excision repair (NER) in Escherichia coli is achieved by at least two steps. In the first step, a helical distortion is recognized,...
DNA damage recognition of nucleotide excision repair (NER) in Escherichia coli is achieved by at least two steps. In the first step, a helical distortion is recognized, which leads to a strand opening at the lesion site. The second step involves the recognition of the type of chemical modification in the single-stranded region of DNA during the processing of the lesions by UvrABC. In the current work, by comparing the efficiencies of UvrABC incision of several types of different DNA adducts, we show that the size and position of the strand opening are dependent on the type of DNA adducts. Optimal incision efficiency for the C8-guanine adducts of 2-aminofluorene (AF) and N-acetyl-2-aminofluorene (AAF) was observed in a bubble of three mismatched nucleotides, whereas the same for C8-guanine adduct of 1-nitropyrene and N(2)-guanine adducts of benzo[a]pyrene diol epoxide (BPDE) was noted in a bubble of six mismatched nucleotides. This suggests that the size of the aromatic ring system of the adduct might influence the extent and number of bases associated with the opened strand region catalyzed by UvrABC. We also showed that the incision efficiency of the AF or AAF adduct was affected by the neighboring DNA sequence context, which, in turn, was the result of differential binding of UvrA to the substrates. The sequence context effect on both incision and binding disappeared when a bubble structure of three bases was introduced at the adduct site. We therefore propose that these effects relate to the initial step of damage recognition of DNA structural distortion. The structure-function relationships in the recognition of the DNA lesions, based on our results, have been discussed.
Topics: Base Sequence; DNA Adducts; DNA Repair; Electrophoretic Mobility Shift Assay; Endodeoxyribonucleases; Escherichia coli Proteins; Molecular Sequence Data
PubMed: 14580212
DOI: 10.1021/bi034446e -
Chemical Research in Toxicology Nov 2017DNA damage impinges on genetic information flow and has significant implications in human disease and aging. Lucidin-3-O-primeveroside (LuP) is an anthraquinone...
DNA damage impinges on genetic information flow and has significant implications in human disease and aging. Lucidin-3-O-primeveroside (LuP) is an anthraquinone derivative present in madder root, which has been used as a coloring agent and food additive. LuP can be metabolically converted to genotoxic compound lucidin, which subsequently forms lucidin-specific N-2'-deoxyguanosine (N-dG) and N-2'-deoxyadenosine (N-dA) DNA adducts. Lucidin is mutagenic and carcinogenic in rodents but has low carcinogenic risks in humans. To understand the molecular mechanism of low carcinogenicity of lucidin in humans, we performed DNA replication assays using site-specifically modified oligodeoxynucleotides containing a structural analogue (LdG) of lucidin-N-dG DNA adduct and determined the crystal structures of DNA polymerase (pol) κ in complex with LdG-bearing DNA and an incoming nucleotide. We examined four human pols (pol η, pol ι, pol κ, and Rev1) in their efficiency and accuracy during DNA replication with LdG; these pols are key players in translesion DNA synthesis. Our results demonstrate that pol κ efficiently and accurately replicates past the LdG adduct, whereas DNA replication by pol η, pol ι is compromised to different extents. Rev1 retains its ability to incorporate dCTP opposite the lesion albeit with decreased efficiency. Two ternary crystal structures of pol κ illustrate that the LdG adduct is accommodated by pol κ at the enzyme active site during insertion and postlesion-extension steps. The unique open active site of pol κ allows the adducted DNA to adopt a standard B-form for accurate DNA replication. Collectively, these biochemical and structural data provide mechanistic insights into the low carcinogenic risk of lucidin in humans.
Topics: Anthraquinones; Carcinogens; Crystallography, X-Ray; DNA Adducts; DNA Damage; DNA Replication; DNA-Directed DNA Polymerase; Humans; Models, Molecular
PubMed: 28972744
DOI: 10.1021/acs.chemrestox.7b00227 -
Cancer Research Sep 2009Formaldehyde is considered carcinogenic to humans by the IARC, but there are no previous reports of formaldehyde-DNA adducts in humans. In this study, we used liquid...
Formaldehyde is considered carcinogenic to humans by the IARC, but there are no previous reports of formaldehyde-DNA adducts in humans. In this study, we used liquid chromatography-electrospray ionization-tandem mass spectrometry to quantify the formaldehyde-DNA adduct N(6)-hydroxymethyldeoxyadenosine (N(6)-HOMe-dAdo) in leukocyte DNA samples from 32 smokers of >or=10 cigarettes per day and 30 nonsmokers. Clear peaks coeluting with the internal standard in two different systems were seen in samples from smokers but rarely in nonsmokers. N(6)-HOMe-dAdo was detected in 29 of 32 smoker samples (mean +/- SD, 179 +/- 205 fmol/micromol dAdo). In contrast, it was detected in only 7 of 30 nonsmoker samples (15.5 +/- 33.8 fmol/micromol dAdo; P < 0.001). The results of this study show remarkable differences between smokers and nonsmokers in levels of a leukocyte formaldehyde-DNA adduct, suggesting a potentially important and previously unrecognized role for formaldehyde as a cause of cancer induced by cigarette smoking.
Topics: Adult; Aged; Chromatography, Liquid; DNA; DNA Adducts; Deoxyadenosines; Female; Formaldehyde; Humans; Leukocytes; Male; Middle Aged; Smoking; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Young Adult
PubMed: 19738046
DOI: 10.1158/0008-5472.CAN-09-1571 -
Chemical Research in Toxicology Feb 2006Acetaldehyde, an ubiquitous mutagen and carcinogen, could be involved in human cancer etiology. Because DNA adducts are important in carcinogenesis, we have used liquid...
Acetaldehyde, an ubiquitous mutagen and carcinogen, could be involved in human cancer etiology. Because DNA adducts are important in carcinogenesis, we have used liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) to explore the presence in human liver DNA of the major acetaldehyde DNA adduct, N2-ethylidenedeoxyguanosine (1). DNA was isolated and enzymatically hydrolyzed in the presence of NaBH3CN, which quantitatively converts adduct 1 to N2-ethyldeoxyguanosine (N2-ethyl-dGuo, 2). [15N5]N2-Ethyl-dGuo was synthesized and used as an internal standard. Adduct 2 was enriched from the hydrolysate by solid phase extraction and analyzed by LC-ESI-MS/MS. Clear peaks were observed for adduct 2 in analyses of human liver DNA, calf thymus DNA, and rat liver DNA. These peaks were not observed, or were much smaller, when the NaBH3CN step was omitted. When the DNA was subjected to neutral thermal hydrolysis prior to NaBH3CN treatment, adduct 2 was not observed. Control experiments using [13C2]acetaldehyde demonstrated that adducts 1 and 2 were not formed as artifacts during DNA isolation and analysis. These results strongly indicate that adduct 1 is present in human liver DNA and demonstrate that it can be quantified as adduct 2. Levels of adduct 2 measured in 12 human liver samples were 534 +/- 245 fmol/micromol dGuo (mean +/- SD). The results of this study establish the presence of an acetaldehyde adduct in human liver DNA and suggest that it is a commonly occurring endogenous DNA adduct.
Topics: Acetaldehyde; Chromatography, High Pressure Liquid; DNA; DNA Adducts; Deoxyguanosine; Humans; Liver; Molecular Structure; Spectrometry, Mass, Electrospray Ionization; Time Factors
PubMed: 16485909
DOI: 10.1021/tx0502948 -
Cancer Chemotherapy and Pharmacology 1996The purpose of this study was to determine the mechanism of the pharmacodynamic interaction between docetaxel/paclitaxel and cisplatin. Cisplatin-induced DNA-adducts and...
The purpose of this study was to determine the mechanism of the pharmacodynamic interaction between docetaxel/paclitaxel and cisplatin. Cisplatin-induced DNA-adducts and cisplatin accumulation were quantitated in peripheral blood leukocytes (WBC). The WBC were obtained from patients treated with docetaxel or paclitaxel in phase I/II studies and were incubated in vitro with cisplatin. In addition, blank whole-blood samples were obtained from patients and healthy subjects and incubated in intro with cisplatin or docetaxel/paclitaxel and cisplatin. The cisplatin-induced DNA-adduct levels measured in WBC after treatment with docetaxel or paclitaxel were significantly lower than those determined in non-pretreated WBC. Docetaxel and paclitaxel reduced the intracellular accumulation of cisplatin in WBC by 46-47%. If the pharmacodynamic interaction between docetaxel/paclitaxel and cisplatin also occurs in other normal tissues such as bone marrow, it may well contribute to the sequence dependent toxicity that has been observed in clinical studies.
Topics: Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Cisplatin; DNA Adducts; DNA, Neoplasm; Docetaxel; Humans; Leukocytes; Paclitaxel; Taxoids
PubMed: 8548886
DOI: 10.1007/s002800050401 -
Environmental Health Perspectives Aug 2006Polycyclic aromatic hydrocarbons (PAHs) are an important class of toxic pollutants released by fossil fuel combustion. Other pollutants include metals and particulate...
Polycyclic aromatic hydrocarbons (PAHs) are an important class of toxic pollutants released by fossil fuel combustion. Other pollutants include metals and particulate matter. PAH-DNA adducts, or benzo[a]pyrene (BaP) adducts as their proxy, provide a chemical-specific measure of individual biologically effective doses that have been associated with increased risk of cancer and adverse birth outcomes. In the present study we examined the relationship between prenatal PAH exposure and fetal and child growth and development in Tongliang, China, where a seasonally operated coal-fired power plant was the major pollution source. In a cohort of 150 nonsmoking women and their newborns enrolled between 4 March 2002 and 19 June 2002, BaP-DNA adducts were measured in maternal and umbilical cord blood obtained at delivery. The number of gestational months occurring during the period of power plant operation provided a second, more general measure of exposure to plant emissions, in terms of duration. High PAH-DNA adduct levels (above the median of detectable adduct level) were associated with decreased birth head circumference (p=0.057) and reduced children's weight at 18 months, 24 months, and 30 months of age (p<0.05), after controlling for potential confounders. In addition, in separate models, longer duration of prenatal exposure was associated with reduced birth length (p=0.033) and reduced children's height at 18 (p=0.001), 24 (p<0.001), and 30 months of age (p<0.001). The findings suggest that exposure to elevated levels of PAHs, with the Tongliang power plant being a significant source, is associated with reduced fetal and child growth in this population.
Topics: Adult; Birth Weight; Blood Specimen Collection; Body Height; Child Development; Child, Preschool; China; Coal; DNA Adducts; Data Interpretation, Statistical; Environmental Pollutants; Female; Fetal Blood; Fetal Development; Growth; Humans; Infant; Infant, Newborn; Polycyclic Aromatic Hydrocarbons; Power Plants; Pregnancy; Pregnancy Outcome; Sex Characteristics; Surveys and Questionnaires
PubMed: 16882543
DOI: 10.1289/ehp.8939 -
International Journal of Molecular... Jul 2021The environmental pollutant benzo[]pyrene (BaP) is a human carcinogen that reacts with DNA after metabolic activation catalysed by cytochromes P450 (CYP) 1A1 and 1B1...
The environmental pollutant benzo[]pyrene (BaP) is a human carcinogen that reacts with DNA after metabolic activation catalysed by cytochromes P450 (CYP) 1A1 and 1B1 together with microsomal epoxide hydrolase. The azo dye Sudan I is a potent inducer of CYP1A1/2. Here, Wistar rats were either treated with single doses of BaP (150 mg/kg bw) or Sudan I (50 mg/kg bw) alone or with both compounds in combination to explore BaP-derived DNA adduct formation . Using P-postlabelling, DNA adducts generated by BaP-7,8-dihydrodiol-9,10-epoxide were found in livers of rats treated with BaP alone or co-exposed to Sudan I. During co-exposure to Sudan I prior to BaP treatment, BaP-DNA adduct levels increased 2.1-fold in comparison to BaP treatment alone. Similarly, hepatic microsomes isolated from rats exposed to Sudan I prior to BaP treatment were also the most effective in generating DNA adducts with the activated metabolites BaP-7,8-dihydrodiol or BaP-9-ol as intermediates. DNA adduct formation correlated with changes in the expression and/or enzyme activities of CYP1A1, 1A2 and 1B1 in hepatic microsomes. Thus, BaP genotoxicity in rats appears to be related to the enhanced expression and/or activity of hepatic CYP1A1/2 and 1B1 caused by exposure of rats to the studied compounds. Our results indicate that the industrially employed azo dye Sudan I potentiates the genotoxicity of the human carcinogen BaP, and exposure to both substances at the same time seems to be hazardous to humans.
Topics: Animals; Benzo(a)pyrene; Carcinogens, Environmental; Coloring Agents; Cytochrome P-450 CYP1A1; DNA Adducts; Liver; Male; Microsomes, Liver; Naphthols; Rats; Rats, Wistar
PubMed: 34360828
DOI: 10.3390/ijms22158062