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Background: Benzo(a)pyrene (B[a]P) is the most widely concerned polycyclic aromatic hydrocarbons (PAHs), which metabolizes benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) in vivo to produce carcinogenic effect on the body. Currently, there is limited research on the role of the variation of metabolic enzymes in this process. Methods: We carried out a study including 752 participants, measured the concentrations of 16 kinds PAHs in both particle and gaseous phases, urinary PAHs metabolites, leukocyte BPDE-DNA adduct and serum BPDE- Albumin (BPDE-Alb) adduct, and calculated daily intake dose (DID) to assess the cumulative exposure of PAHs. We conducted single nucleotide polymorphism sites (SNPs) of metabolic enzymes, explored the exposure–response relationship between the levels of exposure and BPDE adducts using multiple linear regression models. Result: Our results indicated that an interquartile range (IQR) increase in B[a]P, PAHs, BaPeq, 1-hydroxypyrene (1-OHP), 1-hydroxynaphthalene (1-OHNap) and 2-hydroxynaphthalene (2-OHNap) were associated with 26.53 %, 24.24 %, 28.15 %, 39.15 %, 12.85 % and 14.09 % increase in leukocyte BPDE-DNA adduct (all P 0.05). Besides, we also found the polymorphism of CYP1A1(Gly45Asp), CYP2C9 (Ile359Leu), and UGT1A1(downstream) may affect BPDE adducts level. Conclusion: Our results indicated that leukocyte BPDE-DNA adduct could better reflect the exposure to PAHs. Furthermore, the polymorphism of CYP1A1, CYP2C9 and UGT1A1affected the content of BPDE adducts.

BackgroundThe active metabolite of benzo[a]pyrene (BaP), 7,8-dihydroxy-9,10-epoxybenzo[a]pyrene (BPDE), can form adducts with DNA, but the spectrum of BPDE-DNA adducts is unclear. ObjectiveTo identify the distribution of BPDE adduct sites and associated genes at the whole-genome level by chromatin immunoprecipitation followed by sequencing (ChIP-Seq), and serve as a basis for further exploring the toxicological mechanisms of BaP. MethodsHuman bronchial epithelial-like cells (16HBE) were cultured to the fourth generation inthe logarithmic growth phase. Cells were harvested and added to chromatin immunoprecipitation lysis buffer. The lysate was divided into experimental and control groups. The experimental group received a final concentration of 20 μmol·L−1 BPDE solution, while the control group received an equivalent volume of dimethyl sulfoxide solution. The cells were then incubated at 37 °C for 24 h. Chromatin fragments of 100-500 bp were obtained through sonication. BPDE-specific antibody (anti-BPDE 8E11) was used to enrich DNA fragments with BPDE adducts. High-throughput sequencing was conducted to detect BPDE adduct sites. The top 1000 peak sequences were subjected to motif analysis using MEME and DREME software. BPDE adduct target genes at the whole-genome level were annotated, and Gene Ontology (GO) functional analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of BPDE adduct target genes were conducted using bioinformatics techniques. ResultsThe high-throughput sequencing detected a total of 842 BPDE binding sites, distributed across various chromosomes. BPDE covalently bound to both coding and non-coding regions of genes, with 73.9% binding sites located in intergenic regions, 19.6% in intronic regions, and smaller proportions in upstream 2 kilobase, exonic, downstream 2 kilobase, and 5' untranslated regions. Regarding the top 1000 peak sequences, four reliable motifs were identified, revealing that sites rich in adenine (A) and guanine (G) were prone to binding. Through the enrichment analysis of binding sites, a total of 199 BPDE-adduct target genes were identified, with the majority located on chromosomes 1, 5, 7, 12, 17, and X. The GO analysis indicated that these target genes were mainly enriched in nucleic acid and protein binding, participating in the regulation of catalytic activity, transport activity, translation elongation factor activity, and playing important roles in cell division, differentiation, motility, substance transport, and information transfer. The KEGG analysis revealed that these target genes were primarily enriched in pathways related to cardiovascular diseases, cancer, and immune-inflammatory responses. ConclusionUsing ChIP-Seq, 199 BPDE adduct target genes at genome-wide level are identified, impacting biological functions such as cell division, differentiation, motility, substance transport, and information transfer. These genes are closely associated with cardiovascular diseases, tumors, and immune-inflammatory responses.

DNA alkylating drugs have been used as cancer chemotherapy with variable outcomes. The establishment of predictive biomarkers to identify patients who will effectively respond to treatment would allow for the development of personalized therapies. As the degree of interaction of alkylating drug with DNA plays a key role in their mechanism of action, our hypothesis is that the measurement of the DNA adducts formed by alkylating drugs could be used to inform patient stratification. Beginning with busulfan, we took advantage of our DNA adductomic approach to characterize DNA adducts formed by reacting busulfan with calf-thymus DNA. Samples collected from six patients undergoing busulfan-based chemotherapy prior to allogeneic hematopoietic cell transplantation were analyzed for the presence of busulfan-derived DNA adducts. Among the 15 adducts detected in vitro, 12 were observed in the patient blood confirming the presence of a large profile of DNA adducts in vivo. Two of the detected adducts were structurally confirmed by comparison with synthetic standards and quantified in patients. These data confirm our ability to comprehensively characterize busulfan-derived DNA damage and set the stage for the development of methods to support personalized chemotherapy.

Both the number of cells and the collective genome of the gut microbiota outnumber their mammalian hosts, and the metabolic and physiological interactions of the gut microbiota with the host have not yet been fully characterized. Cancer remains one of the leading causes of death, and more research into the critical events that can lead to cancer and the importance of the gut microbiota remains to be determined. The gut microbiota can release microbial molecules that simulate host endogenous processes, such as inflammatory responses, or can alter host metabolism of ingested substances. Both of these reactions can be beneficial or deleterious to the host, and some can be genotoxic, thus contributing to cancer progression. This review focused on the molecular evidence currently available on the mechanistic understanding of how the gut microbiota are involved in human carcinogenesis. We first reviewed the key events of carcinogenesis, especially how DNA damage proceeds to tumor formulation. Then, the current knowledge on host DNA damage attributed to the gut microbiota was summarized, followed by the genotoxic endogenous processes the gut microbiota can induce. Finally, we touched base on the association between specific gut microbiota dysbiosis and different types of cancer and concluded with the up-to-date knowledge as well as future research direction for advancing our understanding of the relationship between the gut microbiota and cancer development.

Purpose: The high incidence of upper urinary tract urothelial carcinoma (UTUC) in Taiwan is largely due to exposure to aristolochic acid (AA), a principal component of Aristolochia-based herbal medicines. Here we systematically review the molecular epidemiology, clinical presentation and biomarkers associated with AA-induced UTUC. Methods: This is a narrative review. Medline, Embase, and Web of Science were searched from inception to December 31, 2021. Studies evaluating the association, detection, and clinical characteristics of AA and UTUC were included. Results: A nationwide database revealed 39% of the Taiwanese population had been exposed to AA-containing herbs between 1997 and 2003. Epidemiological reports revealed AA posed a significantly higher hazard for renal failure and UTUC in herbalists and the general population who ingested AA-containing herbs. The presence of aristolactam-DNA adducts and a distinctive signature mutation, A:T to T:A transversions, located predominantly on the non-transcribed DNA strand, with a strong preference for deoxyadenosine in a consensus sequence (CAG), was observed in many UTUC patients. Clinically, AA-related UTUC patients were characterized by a younger age, female gender, impaired renal function and recurrence of contralateral UTUC. To date, there are no preventive measures, except prophylactic nephrectomy, for subjects at risk of AA nephropathy or AA-related UTUC. Conclusion: AA exposure via Aristolochia-based herbal medicines is a problem throughout Taiwan, resulting in a high incidence of UTUC. Aristolactam-DNA adducts and a distinctive signature mutation, A:T to T:A transversions, can be used as biomarkers to identify AA-related UTUC. AA-related UTUC is associated with a high recurrence rate of contralateral UTUC. [ABSTRACT FROM AUTHOR]

Abstract 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 (H2O2) in tumor tissues, which is catalytically decomposed into a large amount of oxygen bubbles by Ag nanoparticles (NPs). Notably, cisplatin could elevate the intracellular H2O2 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 Fe2+-dependent DNA repair enzyme) by chelating intracellular Fe2+ 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. Graphical Abstract

Both the number of cells and the collective genome of the gut microbiota outnumber their mammalian hosts, and the metabolic and physiological interactions of the gut microbiota with the host have not yet been fully characterized. Cancer remains one of the leading causes of death, and more research into the critical events that can lead to cancer and the importance of the gut microbiota remains to be determined. The gut microbiota can release microbial molecules that simulate host endogenous processes, such as inflammatory responses, or can alter host metabolism of ingested substances. Both of these reactions can be beneficial or deleterious to the host, and some can be genotoxic, thus contributing to cancer progression. This review focused on the molecular evidence currently available on the mechanistic understanding of how the gut microbiota are involved in human carcinogenesis. We first reviewed the key events of carcinogenesis, especially how DNA damage proceeds to tumor formulation. Then, the current knowledge on host DNA damage attributed to the gut microbiota was summarized, followed by the genotoxic endogenous processes the gut microbiota can induce. Finally, we touched base on the association between specific gut microbiota dysbiosis and different types of cancer and concluded with the up-to-date knowledge as well as future research direction for advancing our understanding of the relationship between the gut microbiota and cancer development. [ABSTRACT FROM AUTHOR]

Isoeugenol (IEG) is a natural alkenylbenzene compound which is used as a flavoring additive in foods. However, it has been shown to be a hepatocarcinogen in male B6C3F1 mice. Although there are negative results in several genotoxicity tests, the genotoxicity of IEG in the livers of male mice has not been investigated. To determine whether a genotoxic mechanism is involved in hepatocarcinogenesis, we carried out histopathological analyses, comprehensive DNA adduct analyses, in vivo mutation assays and global gene expression analyses in the livers of male and female B6C3F1 gpt delta mice treated with IEG by gavage at doses of 0, 150, 300 or 600 mg/kg bw/day for 13 weeks. IEG induced slight hepatocyte hypertrophy along with liver weight gain in male mice treated with 300 mg/kg bw/day IEG and more, but not in similarly treated female mice. Comprehensive DNA adduct analyses by LC-MS/MS showed no specific DNA adduct formation in the liver, and there were no changes in gpt or Spi- mutant frequencies in the livers. A pathway analysis of mRNA expression data as determined with a cDNA microarray suggested activation of pathways associated with peroxisome proliferatoractivated receptor (PPAR) α and γ in the livers of male mice. Overall, our data show a lack of genotoxicity in the mechanisms leading to the hepatocarcinogenesis of IEG in mice, and they suggest the involvement of PPARα and γ pathway activation in this process. [ABSTRACT FROM AUTHOR]

Quinones are potent genotoxic agents through generating reactive oxygen species or undergo covalent bonding to modify the nucleobases of DNA. The formation of DNA adducts is an early indication of cancer, as it may lead to gene mutation, thereby initiating tumor development. The present review aims to summarize different types of quinone-induced DNA damages and the corresponding DNA adducts. In addition to the considerably stable naphthoquinone and halobenzoquinones in the environment, quinones are also metabolically activated from estrogen, bisphenol A, ochratoxin A, polychlorinated biphenyls, benzo[a]pyrene and polybrominated diphenyl ethers, in which the inducement from these pollutants to produce DNA adducts were systematically discussed. Liquid chromatography-mass spectrometry (LC-MS)-based method with high accuracy and sensitivity for the detection of DNA adducts in mononucleotides, DNA duplexes, and biological samples was methodically summarized. It is believed that the presence of dione moiety in quinones is an imperative element that induce the formation of DNA adducts. The investigation on DNA adducts is helpful for understanding the generation, transformation, and repair of DNA damages, and for elucidating the underlying mechanism of carcinogenesis. This review provides a new perspective to assess the toxicological potential of quinones, and intends to put forward strategies of analyzing DNA adducts, which act as biomarkers, for indicating the potential health risks of multiDNA damages. [ABSTRACT FROM AUTHOR]

Benzo(a)pyrene (B[a]P) is the most widely concerned polycyclic aromatic hydrocarbons (PAHs), which metabolizes benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) in vivo to produce carcinogenic effect on the body. Currently, there is limited research on the role of the variation of metabolic enzymes in this process. We carried out a study including 752 participants, measured the concentrations of 16 kinds PAHs in both particle and gaseous phases, urinary PAHs metabolites, leukocyte BPDE-DNA adduct and serum BPDE- Albumin (BPDE-Alb) adduct, and calculated daily intake dose (DID) to assess the cumulative exposure of PAHs. We conducted single nucleotide polymorphism sites (SNPs) of metabolic enzymes, explored the exposure–response relationship between the levels of exposure and BPDE adducts using multiple linear regression models. Our results indicated that an interquartile range (IQR) increase in B[a]P, PAHs, BaPeq, 1-hydroxypyrene (1-OHP), 1-hydroxynaphthalene (1-OHNap) and 2-hydroxynaphthalene (2-OHNap) were associated with 26.53 %, 24.24 %, 28.15 %, 39.15 %, 12.85 % and 14.09 % increase in leukocyte BPDE-DNA adduct (all P < 0.05). However, there was no significant correlation between exposure with serum BPDE-Alb adduct (P > 0.05). Besides, we also found the polymorphism of CYP1A1(Gly45Asp), CYP2C9 (Ile359Leu), and UGT1A1(downstream) may affect BPDE adducts level. Our results indicated that leukocyte BPDE-DNA adduct could better reflect the exposure to PAHs. Furthermore, the polymorphism of CYP1A1, CYP2C9 and UGT1A1affected the content of BPDE adducts. [ABSTRACT FROM AUTHOR]

Abstract Background DNA adducts, covalent modifications to DNA due to exposure to specific carcinogens, cause the mispairing of DNA bases, which ultimately results in DNA mutations. DNA methylation in the promoter region, another type of DNA base modification, alters the DNA transcription process, and has been implicated in carcinogenesis in humans due to the down-regulation of tumor suppressor genes. Difficulties are associated with demonstrating the existence of DNA adducts or chemically modified bases in the human urological system. Apart from aristolochic acid-DNA adducts, which cause urothelial carcinoma and endemic nephropathy in a particular geographical area (Balkan), limited information is currently available on DNA adduct profiles in renal cell carcinoma and upper urinary tract urothelial carcinoma, including renal pelvic cancer and ureteral cancer. Method To elucidate the significance of DNA adducts in carcinogenesis in the urothelial system, we investigated 53 DNA adducts in the non-tumoral renal parenchyma and non-tumoral renal pelvis of patients with renal cell carcinoma, upper urinary tract urothelial carcinoma, and other diseases using liquid chromatography coupled with tandem mass spectrometry. A comparative analysis of tissue types, the status of malignancy, and clinical characteristics, including lifestyle factors, was performed. Results C5-Methyl-2′-deoxycytidine, C5-hydroxymethyl-2′-deoxycytidine (5hmdC), C5-formyl-2′-deoxycytidine, 2′-deoxyinosine, C8-oxo-2′-deoxyadenosine, and C8-oxo-2′-deoxyguanosine (8-OHdG) were detected in the renal parenchyma and renal pelvis. 8-OHdG was more frequently detected in the renal pelvis than in the renal cortex and medulla (p = 0.048 and p = 0.038, respectively). 5hmdC levels were significantly lower in the renal pelvis of urothelial carcinoma patients (n = 10) than in the urothelium of patients without urothelial carcinoma (n = 15) (p = 0.010). Regarding 5hmdC levels in the renal cortex and medulla, Spearman’s rank correlation test revealed a negative correlation between age and 5hmdC levels (r = − 0.46, p = 0.018 and r = − 0.45, p = 0.042, respectively). Conclusions The present results revealed a reduction of 5hmdC levels in the non-tumoral urinary tract mucosa of patients with upper urinary tract urothelial carcinoma. Therefore, the urothelial cell epithelia of patients with upper urinary tract cancer, even in non-cancerous areas, may be predisposed to urothelial cancer.

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 (H2O2) in tumor tissues, which is catalytically decomposed into a large amount of oxygen bubbles by Ag nanoparticles (NPs). Notably, cisplatin could elevate the intracellular H2O2 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 Fe2+-dependent DNA repair enzyme) by chelating intracellular Fe2+ 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. [ABSTRACT FROM AUTHOR]

Aflatoxins are a class of carcinogenic mycotoxins produced by Aspergillus fungi, which are widely distributed in nature. Aflatoxin B1 (AFB1) is the most toxic of these compounds and its metabolites have a variety of biological activities, including acute toxicity, teratogenicity, mutagenicity and carcinogenicity, which has been well-characterized to lead to the development of hepatocellular carcinoma (HCC) in humans and animals. This review focuses on the metabolism of AFB1, including epoxidation and DNA adduction, as it concerns the initiation of cancer and the underlying mechanisms. In addition to DNA adduction, inflammation and oxidative stress caused by AFB1 can also participate in the occurrence of cancer. Therefore, the main carcinogenic mechanism of AFB1 related ROS is summarized. This review also describes recent reports of AFB1 exposures in occupational settings. It is hoped that people will pay more attention to occupational health, in order to reduce the incidence of cancer caused by occupational exposure. [ABSTRACT FROM AUTHOR]

Balkan endemic nephropathy (BEN) is a chronic kidney disease that predominantly affects inhabitants of rural farming communities along the Danube River tributaries in the Balkans. Long-standing research has identified dietary exposure to aristolochic acids (AAs) as the principal toxicological cause. This study investigates the pathophysiological role of anemia in BEN, noting its earlier and more severe manifestation in BEN patients compared to those with other chronic kidney diseases. Utilizing a mouse model, our research demonstrates that prolonged exposure to aristolochic acid I (AA-I) (the most prevalent AA variant) leads to significant red blood cell depletion through DNA damage, such as DNA adduct formation in bone marrow, prior to observable kidney function decline. Furthermore, in vitro experiments with kidney cells exposed to lowered oxygen and pH conditions mimicking an anemia environment show enhanced DNA adduct formation, suggesting increased AA-I mutagenicity and carcinogenicity. These findings indicate for the first time a positive feedback mechanism of AA-induced anemia, DNA damage, and kidney impairment in BEN progression. These results not only advance our understanding of the underlying mechanisms of BEN but also highlight anemia as a potential target for early BEN diagnosis and therapy.

Purpose: Pixantrone is a synthetic aza-anthracenedione currently used in the treatment of non-Hodgkin's lymphoma. The drug is firmly established as a poison of the nuclear enzyme topoisomerase II, however, pixantrone can also generate covalent drug-DNA adducts following activation by formaldehyde. While pixantrone-DNA adducts form proficiently in vitro, little evidence is presently at hand to indicate their existence within cells. The molecular nature of these lesions within cancer cells exposed to pixantrone and formaldehyde-releasing prodrugs was characterized along with the cellular responses to their formation. Methods: In vitro crosslinking assays, [14C] scintillation counting analyses and alkaline comet assays were applied to characterize pixantrone-DNA adducts. Flow cytometry, cell growth inhibition and clonogenic assays were used to measure cancer cell kill and survival. Results: Pixantrone-DNA adducts were not detectable in MCF-7 breast cancer cells exposed to [14C] pixantrone (10–40 µM) alone, however the addition of the formaldehyde-releasing prodrug AN9 yielded readily measurable levels of the lesion at ~ 1 adduct per 10 kb of genomic DNA. Co-administration with AN9 completely reversed topoisomerase II-associated DNA damage induction by pixantrone yet potentiated cell kill by the drug, suggesting that pixantrone-DNA adducts may promote a topoisomerase II-independent mechanism of cell death. Pixantrone-DNA adduct-forming treatments generally conferred mild synergism in multiple cell lines in various cell death and clonogenic assays, while pixantrone analogues either incapable or relatively defective in forming DNA adducts demonstrated antagonism when combined with AN9. Conclusions: The features unique to pixantrone-DNA adducts may be leveraged to enhance cancer cell kill and may be used to guide the design of pixantrone analogues that generate adducts with more favorable anticancer properties. [ABSTRACT FROM AUTHOR]

Abstract Background A comprehensive understanding of DNA adducts, one of the most plausible origins of cancer mutations, is still elusive, especially in human tissues in clinical settings. Recent technological developments have facilitated the identification of multiple DNA adducts in a single experiment. Only a few attempts toward this “DNA adductome approach” in human tissues have been reported. Geospatial information on DNA adducts in human organs has been scarce. Aim Mass spectrometry of human gastric mucosal DNA was performed to identify DNA adducts associated with environmental factors. Materials and methods From 59 subjects who had received gastrectomy for gastric cancer, 306 samples of nontumor tissues and 15 samples of tumors (14 cases) were taken for DNA adductome analysis. Gastric nontumor tissue from autopsies of 7 subjects without gastric cancer (urothelial cancer, hepatocellular carcinoma, lung cancer each; the other four cases were without any cancers) was also investigated. Briefly, DNA was extracted from each sample with antioxidants, digested into nucleosides, separated by liquid chromatography, and then electrospray-ionized. Specific DNA adducts were identified by mass/charge number and column retention time compared to standards. Information on lifestyle factors such as tobacco smoking and alcohol drinking was taken from the clinical records of each subject. Results Seven DNA adducts, including modified bases, C5-methyl-2′-deoxycytidine, 2′-deoxyinosine, C5-hydroxymethyl-2′-deoxycytidine, N6-methyl-2′-deoxyadenosine, 1,N6-etheno-2′-deoxyadenosine, N6-hydroxymethyl-2′-deoxyadenosine, and C8-oxo-2′-deoxyguanosine, were identified in the human stomach and characterized. Intraindividual differences according to the multiple sites of these adducts were noted but were less substantial than interindividual differences. N6-hydroxymethyl-2′-deoxyadenosine was identified in the human stomach for the first time. The amount of C5-hydroxymethyl-2′-deoxycytidine was higher in the stomachs of subjects without gastric cancer than in the nontumor and tumor portions of the stomach in gastric cancer patients. Higher levels of 1,N6-etheno-2′-deoxyadenosine were detected in the subjects who reported both smoking and drinking than in those without these habits. These DNA adducts showed considerable correlations with each other. Conclusions We characterized 7 DNA adducts in the nontumor portion of the human stomach in both gastric cancer subjects and nongastric cancer subjects. A reduction in C5-hydroxymethyl-dC even in the nontumor mucosa of patients with gastric cancer was observed. Smoking and drinking habits significantly influenced the quantity of one of the lipid peroxidation-derived adducts, etheno-dA. A more expansive DNA adductome profile would provide a comprehensive understanding of the origin of human cancer in the future.

The exposure of human DNA to genotoxic compounds induces the formation of covalent DNA adducts, which may contribute to the initiation of carcinogenesis. Liquid chromatography (LC) coupled with high-resolution mass spectrometry (HRMS) is a powerful tool for DNA adductomics, a new research field aiming at screening known and unknown DNA adducts in biological samples. The lack of databases and bioinformatics tool in this field limits the applicability of DNA adductomics. Establishing a comprehensive database will make the identification process faster and more efficient and will provide new insight into the occurrence of DNA modification from a wide range of genotoxicants. In this paper, we present a four-step approach used to compile and curate a database for the annotation of DNA adducts in biological samples. The first step included a literature search, selecting only DNA adducts that were unequivocally identified by either comparison with reference standards or with nuclear magnetic resonance (NMR), and tentatively identified by tandem HRMS/MS. The second step consisted in harmonizing structures, molecular formulas, and names, for building a systematic database of 279 DNA adducts. The source, the study design and the technique used for DNA adduct identification were reported. The third step consisted in implementing the database with 303 new potential DNA adducts coming from different combinations of genotoxicants with nucleobases, and reporting monoisotopic masses, chemical formulas, .cdxml files, .mol files, SMILES, InChI, InChIKey and IUPAC nomenclature. In the fourth step, a preliminary spectral library was built by acquiring experimental MS/MS spectra of 15 reference standards, generating in silico MS/MS fragments for all the adducts, and reporting both experimental and predicted fragments into interactive web datatables. The database, including 582 entries, is publicly available (https://gitlab.com/nexs-metabolomics/projects/dna_adductomics_database). This database is a powerful tool for the annotation of DNA adducts measured in (HR)MS. The inclusion of metadata indicating the source of DNA adducts, the study design and technique used, allows for prioritization of the DNA adducts of interests and/or to enhance the annotation confidence. DNA adducts identification can be further improved by integrating the present database with the generation of authentic MS/MS spectra, and with user-friendly bioinformatics tools.

Yahdiana Harahap,1,2 Aurelia Maria Vianney,1 Herman Suryadi1 1Faculty of Pharmacy, Universitas Indonesia, Depok, West Java, 16424, Indonesia; 2Indonesia Defense University, Bogor, 16810, West Java, IndonesiaCorrespondence: Yahdiana Harahap Email yahdiana@farmasi.ui.ac.idBackground: Cyclophosphamide is a nitrogen mustard chemotherapy drug that damages DNA through alkylation in the DNA base and produces DNA adducts. Alkylation that occurs in the N7 position of guanine base has a cytotoxic effect which is useful for cancer therapy. However, the alkylation that occurs in the O6 position of guanine bases can have mutagenic and carcinogenic effects that can trigger secondary cancer. This carcinogenic compound can be found in very low concentrations in cancer patients who had been receiving alkylating agents as their anticancer therapy. Analysis of O6-methylguanine can be one of the ways of therapeutic drug monitoring to avoid secondary cancer risk. This study aims to develop a sensitive, selective, and validated analytical method using Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS).Methods: Analysis of O6-methylguanine was done in Dried Blood Spot (DBS) and using allopurinol as an internal standard. The optimal analysis conditions were obtained using a C18 Acquity® Bridged Ethylene Hybrid (BEH) column (1.7 μm, 100 mm x 2.1 mm); mobile phase was 0.05% formic acid - acetonitrile (95:5 v/v); flow rate 0.1 mL/minute; gradient elution for 6 minutes; and detection at m/z 165.95 > 149 for O6-methylguanine and m/z 136.9 > 110 for allopurinol.Results: The present study has fulfilled the FDA validation parameter requirements. The method provides rapid, sensitive, and selective analysis of O6-methylguanine using UPLC-MS/MS with a linear concentration range between 0.5– 20 ng/mL.Keywords: cyclophosphamide, DNA adduct, O6-methylguanine, UPLC-MS/MS, dried blood spot

Current genotoxicity assessment methods are mainly employed to verify the genotoxic safety of drugs, but do not allow for rapid screening of specific genotoxic impurities (GTIs). In this study, a new approach for the recognition of GTIs has been proposed. It is to expose the complex samples to an in vitro nucleoside incubation model, and then draw complete DNA adduct profiles to infer the structures of potential genotoxic impurities (PGIs). Subsequently, the genotoxicity is confirmed in human by 3D bioprinted human liver organoids. To verify the feasibility of the approach, lansoprazole chloride compound (Lanchlor), a PGI during the synthesis of lansoprazole, was selected as the model drug. After confirming genotoxicity by Comet assay, it was exposed to different models to map and compare the DNA adduct profiles by LC-MS/MS. The results showed Lanchlor could generate diverse DNA adducts, revealing firstly its genotoxicity at molecular mechanism of action. Furthermore, the largest variety and content of DNA adducts were observed in the nucleoside incubation model, while the human liver organoids exhibited similar results with rats. The results showed that the combination of DNA adductomics and 3D bioprinted organoids were useful for the rapid screening of GTIs. [Display omitted] • The genotoxicity of Lanchlor was affirmed. • The specific induced DNA adduct profiles of Lanchlor were first unveiled. • UiO-66, as a nanosorbent, was applied for the enrichment of DNA adducts for the first time. • An innovative strategy for rapid in vitro screening of GTIs was introduced and successfully validated. [ABSTRACT FROM AUTHOR]

Penicillium polonicum K. M. Zaleski, which is common on foodstuffs in Balkan regions that are notable for their history of endemic nephropathy, has been shown experimentally to cause a striking histopathological renal change in rats that are given feed contaminated by this fungus. The nephrotoxic agent(s) are only partially characterized. The principal change seen in the cortico-medullary region is karyocytomegaly, but apoptosis, identified with the ApopTag® methodology, is the first response to a dietary extract of P. polonicum-molded wheat after a few days of exposure. Chromatin debris migrates along the nephrons into the medulla, but whether the damaged epithelial fate is via autophagy is unclear. In intermittent exposure experiments, renal apoptosis was resolved with the cessation of exposure and was restored with renewed exposure. Apoptosis became less evident after 3 months of chronic exposure. In contrast, a relatively high dose of dietary ochratoxin A, a potent nephrocarcinogen in male rats after many months of dietary exposure, gave no evidence of apoptosis in asymptomatic weanlings over a few days of dietary exposure. This was attributed to a masking effect by concomitant marked histological disruption in renal tissue. However, in young adults, renal apoptosis was a primary outcome of dietary exposure to either the P. polonicum extract or to ochratoxin A, but the histopathological response to the former was less distorted. The apparent conflicted use in the literature of P. polonicum as a descriptor is highlighted. [ABSTRACT FROM AUTHOR]

Vinyl acetate monomer (VAM) is heavily used to synthesize polymers. Previous studies have shown that inhaled VAM, being metabolized to acetaldehyde, may form DNA adducts including N2-ethylidene-deoxyguanosine (N2-EtD-dG), which may subsequently cause mutations and contribute to its carcinogenesis. Currently, there is little knowledge on the molecular dosimetry between VAM exposure and DNA adducts under dosages relevant to human exposure. In this study, 0.02, 0.1, 1, 10, 50, 200, and 600 ppm VAM were exposed to rats by inhalation for 14 days (6 h/day). The use of [13C2]-VAM allows unambiguous differentiation and quantification of the exogenous and endogenous N2-EtD-dG by highly sensitive LC-MS/MS. Our data indicate that VAM-induced exogenous DNA adducts were formed in a non-linear manner. Exogenous DNA adducts were only detected in the nasal epithelium of rats exposed to 10, 50, 200, and 600 ppm VAM, whereas endogenous adducts were found in all nasal and other tissues analyzed. In addition, ratios of exogenous/endogenous DNA adducts were less than 1 with the dose up to 50 ppm, indicating that endogenous DNA adducts are predominant at low VAM concentrations. Moreover, differential dose-response in terms of exogenous DNA adduct formation were observed between nasal respiratory and olfactory epithelium. Furthermore, the lack of exogenous DNA adducts in distant tissues, including peripheral blood mononuclear cells, liver, brain, and bone marrow, indicates that VAM and/or its metabolite do not distribute systemically to cause DNA damage in distant tissues. Together, these results provided new molecular dosimetry to improve science-based cancer risk assessments of VAM. [ABSTRACT FROM AUTHOR]

Abstract Background Further knowledge on modifiable aging risk factors is required to mitigate the increasing burden of age-related diseases in a rapidly growing global demographic of elderly individuals. We explored the effect of everyday exposure to polycyclic aromatic hydrocarbons (PAHs), which are fundamental constituents of air pollution, on cellular biological aging. This was determined via the analysis of leukocyte telomere length (LTL), mitochondrial DNA copy number (LmtDNAcn), and by the formation of anti-benzo[a]pyrene diolepoxide (B[a]PDE–DNA) adducts. Methods The study population consisted of 585 individuals living in North-East Italy. PAH exposure (diet, indoor activities, outdoor activities, traffic, and residential exposure) and smoking behavior were assessed by questionnaire and anti-B[a]PDE–DNA by high-performance-liquid-chromatography. LTL, LmtDNAcn and genetic polymorphisms [glutathione S-transferase M1 and T1 (GSTM1; GSTT1)] were measured by polymerase chain reaction. Structural equation modelling analysis evaluated these complex relationships. Results Anti-B[a]PDE–DNA enhanced with PAH exposure (p = 0.005) and active smoking (p = 0.0001), whereas decreased with detoxifying GSTM1 (p = 0.021) and in females (p = 0.0001). Subsequently, LTL and LmtDNAcn reduced with anti-B[a]PDE–DNA (p = 0.028 and p = 0.018), particularly in males (p = 0.006 and p = 0.0001). Only LTL shortened with age (p = 0.001) while elongated with active smoking (p = 0.0001). Besides this, the most significant determinants of PAH exposure that raised anti-B[a]PDE–DNA were indoor and diet (p = 0.0001), the least was outdoor (p = 0.003). Conclusion New findings stemming from our study suggest that certain preventable everyday life exposures to PAHs reduce LTL and LmtDNAcn. In particular, the clear association with indoor activities, diet, and gender opens new perspectives for tailored preventive measures in age-related diseases. Capsule Everyday life exposure to polycyclic aromatic hydrocarbons reduces leukocyte telomere length and mitochondrial DNA copy number through anti-B[a]PDE-DNA adduct formation.

Polycyclic aromatic hydrocarbons, like benzo[a]pyrene (BaP), are ubiquitous environmental pollutants and potent ovarian toxicants. The transcription factor NRF2 is an important regulator of the cellular response to electrophilic toxicants like BaP and to oxidative stress. NRF2 regulates transcription of genes involved in the detoxification of reactive metabolites of BaP and reactive oxygen species. We therefore hypothesized that Nrf2-/- mice have accelerated ovarian aging and increased sensitivity to the ovarian toxicity of BaP. A single injection of BaP dose-dependently depleted ovarian follicles in Nrf2+/+ and Nrf2-/- mice, but the effects of BaP were not enhanced in the absence of Nrf2. Similarly, Nrf2-/- mice did not have increased ovarian BaP DNA adduct formation compared to Nrf2+/+ mice. Ovarian follicle numbers did not differ between peripubertal Nrf2-/- and Nrf2+/+ mice, but by middle age, Nrf2-/- mice had significantly fewer primordial follicles than Nrf2+/+ mice, consistent with accelerated ovarian aging.

Background: DNA adducts, covalent modifications to DNA due to exposure to specific carcinogens, cause the mispairing of DNA bases, which ultimately results in DNA mutations. DNA methylation in the promoter region, another type of DNA base modification, alters the DNA transcription process, and has been implicated in carcinogenesis in humans due to the down-regulation of tumor suppressor genes. Difficulties are associated with demonstrating the existence of DNA adducts or chemically modified bases in the human urological system. Apart from aristolochic acid-DNA adducts, which cause urothelial carcinoma and endemic nephropathy in a particular geographical area (Balkan), limited information is currently available on DNA adduct profiles in renal cell carcinoma and upper urinary tract urothelial carcinoma, including renal pelvic cancer and ureteral cancer. Method: To elucidate the significance of DNA adducts in carcinogenesis in the urothelial system, we investigated 53 DNA adducts in the non-tumoral renal parenchyma and non-tumoral renal pelvis of patients with renal cell carcinoma, upper urinary tract urothelial carcinoma, and other diseases using liquid chromatography coupled with tandem mass spectrometry. A comparative analysis of tissue types, the status of malignancy, and clinical characteristics, including lifestyle factors, was performed. Results: C5-Methyl-2′-deoxycytidine, C5-hydroxymethyl-2′-deoxycytidine (5hmdC), C5-formyl-2′-deoxycytidine, 2′-deoxyinosine, C8-oxo-2′-deoxyadenosine, and C8-oxo-2′-deoxyguanosine (8-OHdG) were detected in the renal parenchyma and renal pelvis. 8-OHdG was more frequently detected in the renal pelvis than in the renal cortex and medulla (p = 0.048 and p = 0.038, respectively). 5hmdC levels were significantly lower in the renal pelvis of urothelial carcinoma patients (n = 10) than in the urothelium of patients without urothelial carcinoma (n = 15) (p = 0.010). Regarding 5hmdC levels in the renal cortex and medulla, Spearman's rank correlation test revealed a negative correlation between age and 5hmdC levels (r = − 0.46, p = 0.018 and r = − 0.45, p = 0.042, respectively). Conclusions: The present results revealed a reduction of 5hmdC levels in the non-tumoral urinary tract mucosa of patients with upper urinary tract urothelial carcinoma. Therefore, the urothelial cell epithelia of patients with upper urinary tract cancer, even in non-cancerous areas, may be predisposed to urothelial cancer. [ABSTRACT FROM AUTHOR]

DNA damage in the brain is influenced by endogenous processes and metabolism along with exogenous exposures. Accumulation of DNA damage in the brain can contribute to various neurological disorders, including neurodegenerative diseases and neuropsychiatric disorders. Traditional methods for assessing DNA damage in the brain, such as immunohistochemistry and mass spectrometry, have provided valuable insights but are limited by their inability to map specific DNA adducts and regional distributions within the brain or genome. Recent advancements in DNA damage detection methods offer new opportunities to address these limitations and further our understanding of DNA damage and repair in the brain. Here, we review emerging techniques offering more precise and sensitive ways to detect and quantify DNA lesions in the brain or neural cells. We highlight the advancements and applications of these techniques and discuss their potential for determining the role of DNA damage in neurological disease.

• Documentation of SM-DNA adducts detected by LC–MS/MS technology. • Characterization of SM-induced biomarkers to help understand SM toxicity mechanism. • Indication of other potential DNA adducts induced by SM and its secondary effects. Sulfur mustard (SM) is a blister chemical warfare agent with severe cytotoxicity and genotoxicity. It can extensively alkylate important macromolecules in organisms, such as proteins, DNA, and lipids, and produce a series of metabolites, among which the characteristic ones can be used as biomarkers. The exact toxicological mechanisms of SM remain unclear but mainly involve the DNA lesions induced by alkylation and oxidative stress caused by glutathione depletion. Various methods have been used to analyze DNA damage caused by SM. Among these methods, liquid chromatography-tandem mass spectrometry (LC–MS/MS) technology stands out and makes it possible to observe damage in view of biomarkers induced by SM. Sample preparation is critical for detection by LC–MS/MS and mainly includes DNA isolation, adduct hydrolysis, and adduct purification. Moreover, optimization of chromatographic conditions, selection of MS transitions, and quantitative strategies are also essential. SM-DNA adducts are generally considered to be N7-HETEG, O6-HETEG, N7-BisG, and N3-HETEA. This article proposes some other possibilities of SM-DNA adducts for the identification of SM genotoxicity. [ABSTRACT FROM AUTHOR]

Background: A comprehensive understanding of DNA adducts, one of the most plausible origins of cancer mutations, is still elusive, especially in human tissues in clinical settings. Recent technological developments have facilitated the identification of multiple DNA adducts in a single experiment. Only a few attempts toward this "DNA adductome approach" in human tissues have been reported. Geospatial information on DNA adducts in human organs has been scarce. Aim: Mass spectrometry of human gastric mucosal DNA was performed to identify DNA adducts associated with environmental factors. Materials and methods: From 59 subjects who had received gastrectomy for gastric cancer, 306 samples of nontumor tissues and 15 samples of tumors (14 cases) were taken for DNA adductome analysis. Gastric nontumor tissue from autopsies of 7 subjects without gastric cancer (urothelial cancer, hepatocellular carcinoma, lung cancer each; the other four cases were without any cancers) was also investigated. Briefly, DNA was extracted from each sample with antioxidants, digested into nucleosides, separated by liquid chromatography, and then electrospray-ionized. Specific DNA adducts were identified by mass/charge number and column retention time compared to standards. Information on lifestyle factors such as tobacco smoking and alcohol drinking was taken from the clinical records of each subject. Results: Seven DNA adducts, including modified bases, C5-methyl-2′-deoxycytidine, 2′-deoxyinosine, C5-hydroxymethyl-2′-deoxycytidine, N6-methyl-2′-deoxyadenosine, 1,N6-etheno-2′-deoxyadenosine, N6-hydroxymethyl-2′-deoxyadenosine, and C8-oxo-2′-deoxyguanosine, were identified in the human stomach and characterized. Intraindividual differences according to the multiple sites of these adducts were noted but were less substantial than interindividual differences. N6-hydroxymethyl-2′-deoxyadenosine was identified in the human stomach for the first time. The amount of C5-hydroxymethyl-2′-deoxycytidine was higher in the stomachs of subjects without gastric cancer than in the nontumor and tumor portions of the stomach in gastric cancer patients. Higher levels of 1,N6-etheno-2′-deoxyadenosine were detected in the subjects who reported both smoking and drinking than in those without these habits. These DNA adducts showed considerable correlations with each other. Conclusions: We characterized 7 DNA adducts in the nontumor portion of the human stomach in both gastric cancer subjects and nongastric cancer subjects. A reduction in C5-hydroxymethyl-dC even in the nontumor mucosa of patients with gastric cancer was observed. Smoking and drinking habits significantly influenced the quantity of one of the lipid peroxidation-derived adducts, etheno-dA. A more expansive DNA adductome profile would provide a comprehensive understanding of the origin of human cancer in the future. [ABSTRACT FROM AUTHOR]

Education regarding the health effects associated with tobacco use has made important progress worldwide over the last few decades. Still, tobacco remains a significant cause of cancer and other diseases. As a result, significant worldwide morbidity and mortality is still attributable to tobacco use in modern times. Research into tobacco products, the carcinogens they contain, and how users metabolize them is an important benefit to the advancement of research aimed at reducing harm associated with tobacco use. This review summarizes the use of this type of research to study tobacco users’ risk of developing cancer, especially head and neck cancer. In addition, we discuss the use of tobacco research to provide support for increasing levels of federal regulation of tobacco products. Level of Evidence 4.

Chemical carcinogenesis is focused on the formation of DNA adducts, a form of DNA damage caused by covalent binding of a chemical moiety to DNA. The detection of carcinogen‐DNA adducts in human tissues, along with demonstration of mutagenicity/carcinogenicity in experimental systems, and validation of adducts as biomarkers of environmental exposure and indicators of cancer risk in molecular epidemiological studies suggests a pivotal role of DNA adducts in cancer development. However, accurate measurement of DNA adducts in varied biological samples is challenging. Advances in mass spectrometry have prompted the development of DNA adductome analysis, an emerging method that simultaneously screens for multiple DNA adducts and provides relevant structural information. In this review, we summarize the basic principle and applications of DNA adductome analysis that would contribute to the elucidation of the environmental causes of cancer. Based on parallel developments in several fields, including next‐generation sequencing, we describe a new approach used to explore cancer etiology, which integrates analyses of DNA adductome data and mutational signatures derived from whole‐genome/exome sequencing. [ABSTRACT FROM AUTHOR]

• The Alternaria mycotoxin altertoxin II contains an epoxide group. • Incubation of altertoxin II with DNA gives rise to three covalent DNA adducts. • Two adducts with guanine and one with cytosine were identified by LC–MS. • The direct reactivity of altertoxin II with DNA may explain its high mutagenicity. Fungi of the genus Alternaria infest many agricultural crops and produce numerous mycotoxins, of which altertoxin II (ATX II) is one of the most mutagenic metabolites. ATX II carries an epoxide group but the formation of DNA adducts has not been demonstrated to date. We report now that ATX II gives rise to two covalent adducts with guanine when incubated with DNA under cell-free conditions. These adducts were demonstrated by LC-high resolution MS after enzymatic degradation of the incubated DNA to deoxynucleosides. The major adduct results from the covalent binding of ATX II, presumably through the epoxide group, to guanine, whereas the minor guanine adduct is derived from the major one by the elimination of two equivalents of water. In addition, a third adduct was detected, formed through covalent binding of ATX II to cytosine followed by the loss of two equivalents of water. The direct DNA reactivity of ATX II may explain its high mutagenicity. [ABSTRACT FROM AUTHOR]

Benzene, a ubiquitous human carcinogen, forms DNA adducts through its metabolites such as p-benzoquinone (p-BQ) and hydroquinone (HQ). N(2)-(4-Hydroxyphenyl)-2'-deoxyguanosine (N(2)-4-HOPh-dG) is the principal adduct identified in vivo by (32)P-postlabeling in cells or animals treated with p-BQ or HQ. To study its effect on repair specificity and replication fidelity, we recently synthesized defined oligonucleotides containing a site-specific adduct using phosphoramidite chemistry. We here report the repair of this adduct by Escherichia coli UvrABC complex, which performs the initial damage recognition and incision steps in the nucleotide excision repair (NER) pathway. We first showed that the p-BQ-treated plasmid was efficiently cleaved by the complex, indicating the formation of DNA lesions that are substrates for NER. Using a 40-mer substrate, we found that UvrABC incises the DNA strand containing N(2)-4-HOPh-dG in a dose- and time-dependent manner. The specificity of such repair was also compared with that of DNA glycosylases and damage-specific endonucleases of E. coli, both of which were found to have no detectable activity toward N(2)-4-HOPh-dG. To understand why this adduct is specifically recognized and processed by UvrABC, molecular modeling studies were performed. Analysis of molecular dynamics trajectories showed that stable G:C-like hydrogen bonding patterns of all three Watson-Crick hydrogen bonds are present within the N(2)-4-HOPh-G:C base pair, with the hydroxyphenyl ring at an almost planar position. In addition, N(2)-4-HOPh-dG has a tendency to form more stable stacking interactions than a normal G in B-type DNA. These conformational properties may be critical in differential recognition of this adduct by specific repair enzymes.

A major limitation in the pharmacological treatment of clinically detectable primary cancers and their metastases is their limited accessibility to anti-cancer drugs (cytostatics, inhibitory antibodies, small-molecule inhibitors) critically impairing therapeutic efficacies. Investigations on the tissue distribution of such drugs are rare and have only been based on fresh frozen material or methanol-fixed cell culture cells so far. In this paper, we expand the detection of cisplatin-induced DNA adducts and anthracyclines as well as therapeutic antibodies to routinely prepared formalin-fixed, paraffin-embedded sections (FFPE). Using pre-treated cell lines prepared as FFPE samples comparable to tissues from routine analysis, we demonstrate that our method allows for the detection of chemotherapeutics (anthracyclines by autofluorescence, cisplatin by immune detection of DNA adducts) as well as therapeutic antibodies. This methodology thus allows for analyzing archival FFPE tissues, as demonstrated here for the detection of cisplatin, doxorubicin and trastuzumab in FFPE sections of tumor xenografts from drug-treated mice. Analyzing human tumor samples, this will lead to new insights into the tissue penetration of drugs. [ABSTRACT FROM AUTHOR]

Estragole, naturally occurring in a variety of herbs and spices, can form DNA adducts after bioactivation. Estragole DNA adduct formation and repair was studied in in vitro liver cell models, and a molecular dynamics simulation was used to investigate the conformation dependent (in)efficiency of N2-(trans-isoestragol-3′-yl)-2′-deoxyguanosine (E-3′-N2-dG) DNA adduct repair. HepG2, HepaRG cells, primary rat hepatocytes and CHO cells (including CHO wild-type and three NER-deficient mutants) were exposed to 50 μM estragole or 1′-hydroxyestragole and DNA adduct formation was quantified by LC–MS immediately following exposure and after a period of repair. Results obtained from CHO cell lines indicated that NER plays a role in repair of E-3′-N2-dG adducts, however, with limited efficiency since in the CHO wt cells 80% DNA adducts remained upon 24 h repair. Inefficiency of DNA repair was also found in HepaRG cells and primary rat hepatocytes. Changes in DNA structure resulting from E-3′-N2-dG adduct formation were investigated by molecular dynamics simulations. Results from molecular dynamics simulations revealed that conformational changes in double-stranded DNA by E-3′-N2-dG adduct formation are small, providing a possible explanation for the restrained repair, which may require larger distortions in the DNA structure. NER-mediated enzymatic repair of E-3′-N2-dG DNA adducts upon exposure to estragole will be limited, providing opportunities for accumulation of damage upon repeated daily exposure. The inability of this enzymatic repair is likely due to a limited distortion of the DNA double-stranded helix resulting in inefficient activation of nucleotide excision repair. [ABSTRACT FROM AUTHOR]

Hazardous chemicals in the environment and diet or their electrophilic metabolites can form adducts with genomic DNA, which can lead to mutations and the initiation of cancer. In addition, reactive intermediates can be generated in the body through oxidative stress and damage the genome. The identification and measurement of DNA adducts are required for understanding exposure and the causal role of a genotoxic chemical in cancer risk. Over the past three decades, 32P‐postlabeling, immunoassays, gas chromatography/mass spectrometry, and liquid chromatography/mass spectrometry (LC/MS) methods have been established to assess exposures to chemicals through measurements of DNA adducts. It is now possible to measure some DNA adducts in human biopsy samples, by LC/MS, with as little as several milligrams of tissue. In this review article, we highlight the formation and biological effects of DNA adducts, and highlight our advances in human biomonitoring by mass spectrometric analysis of formalin‐fixed paraffin‐embedded tissues, untapped biospecimens for carcinogen DNA adduct biomarker research. [ABSTRACT FROM AUTHOR]

• 4-FE 2 , like E 2 , induced mammary tumors in ACI rats whereas 2-FE 2 did not. • Both 4-FE 2 and 2-FE 2 showed high uterotrophic potency. • Estrogenic potential may not be the sole factor driving mammary tumorigenesis. • The carcinogenic effect may occur through the metabolic activation of 2−OHE 2. Fluorination preventing metabolic hydroxylation of 17β-estradiol (E 2) was applied to investigate the mechanisms underlying estrogen-induced carcinogenesis. Either 2-fluoro-17β-estradiol (2-FE 2) or 4-fluoro-17β-estradiol (4-FE 2) was administered subcutaneously for 52 weeks to August Copenhagen Irish (ACI) rats, the preferred animal model for human breast cancer. 4-FE 2 induced frequent mammary tumors whereas 2-FE 2 did not. The cumulative incidence of mammary tumors in rats treated with 4-FE 2 was comparable to that observed with E 2. The carcinogenic results were supported by histological examination of mammary glands of fluorinated estrogen-treated ACI rats. To evaluate the estrogenic potential of the fluorinated estrogens, 2-FE 2 or 4-FE 2 was administrated subcutaneously to ovariectomized rats. Both 4-FE 2 and 2-FE 2 showed high uterotrophic potency. Our results indicate that estrogenic potential may not be the sole factor driving mammary tumorigenesis. Since fluorination inhibits metabolic hydroxylation of E 2 at the substituted position, the carcinogenic effect may occur through the metabolic activation of 2-hydroxylated E 2 , in combination with the compound's estrogenic potency. [ABSTRACT FROM AUTHOR]

The tumor suppressor p53, encoded by TP53, is known as the "guardian of the genome." Sulfotransferases (SULTs) are involved in the metabolism of alkylated polycyclic aromatic hydrocarbons such as 1‐hydroxymethylpyrene (1‐HMP), which is a known substrate for SULT1A1. To investigate the impact of TP53 on the metabolic activation of 1‐HMP, a panel of isogenic human colorectal HCT116 cells having TP53(+/+), TP53(+/−), or TP53(−/−) were treated with 10 μM 1‐HMP for 24 hr. 1‐HMP‐DNA adduct formation was determined by ultraperformance liquid chromatography‐tandem mass spectrometry analysis, which quantified two nucleoside adducts N2‐(1‐methylpyrenyl)‐2′‐deoxyguanosine and N6‐(1‐methylpyrenyl)‐2′‐deoxyadenosine. 1‐HMP treatment resulted in significantly (~40‐fold) higher DNA adduct levels in TP53(+/+) cells than in the other cell lines. Higher levels of 1‐HMP‐induced DNA adducts in TP53(+/+) cells correlated with higher basal expression of SULT1A1/3 in this cell line, but 1‐HMP treatment showed no effect on the expression of this protein. These results indicate that the cellular TP53 status is linked to the SULT1A1/3‐mediated bioactivation of 1‐HMP, thereby broadening the spectrum of p53's targets. Environ. Mol. Mutagen., 60:752–758, 2019. © 2019 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Adductomics novel and emerging discipline in the toxicological research emphasizes on adducts formed by reactive chemical agents with biological molecules in living organisms. Development in analytical methods propelled the application and utility of adductomics in interdisciplinary sciences. This review endeavors to add a new dimension where comprehensive insights into diverse applications of adductomics in addressing some of society’s pressing challenges are provided. Also focuses on diverse applications of adductomics include: forecasting risk of chronic diseases triggered by reactive agents and predicting carcinogenesis induced by tobacco smoking; assessing chemical agents’ toxicity and supplementing genotoxicity studies; designing personalized medication and precision treatment in cancer chemotherapy; appraising environmental quality or extent of pollution using biological systems; crafting tools and techniques for diagnosis of diseases and detecting food contaminants; furnishing exposure profile of the individual to electrophiles; and assisting regulatory agencies in risk assessment of reactive chemical agents. Characterizing adducts that are present in extremely low concentrations is an exigent task and more over absence of dedicated database to identify adducts is further exacerbating the problem of adduct diagnosis. In addition, there is scope of improvement in sample preparation methods and data processing software and algorithms for accurate assessment of adducts.

Background: Field cancerization is a popular concept regarding where cancer cells arise in a plane, such as the opened-up gastrointestinal mucosa. The geospatial distribution of DNA adducts, some of which are believed to initiate mutation, may be a clue to understanding the landscape of the preferred occurrence of gastric cancer in the human stomach, such that the occurrence is much more frequent in the lesser curvature than in the greater curvature. Methods: Seven DNA adducts, C5-methyl-2′-deoxycytidine, 2′-deoxyinosine, C5-hydroxymethyl-2′-deoxycytidine, N6-methyl-2′-deoxyadenosine, 1,N6-etheno-2′-deoxyadenosine, N6-hydroxymethyl-2′-deoxyadenosine, and C8-oxo-2′-deoxyguanosine, from different points and zones of the human stomach were semi quantitatively measured by liquid chromatography/tandem mass spectrometry. The differences in the quantity of these DNA adducts from the lesser and greater curvature, the upper, middle and lower third zones, the anterior and posterior wall of the stomach, and the mucosae distant from and near the tumor were compared to determine whether the location preference of cancer in the stomach could be explained by the distribution of these DNA adducts. Comparisons were conducted considering the tumor locations and operation methods. Conclusions: Regarding the DNA adducts investigated, significant differences in quantities and locations in the whole stomach were not noted; thus, these DNA adducts do not explain the preferential occurrence of cancer in particular locations of the human stomach.

Abstract Benzo[a]pyrene (BaP) is a well-studied pro-carcinogen that is metabolically activated by cytochrome P450 enzymes. Cytochrome P4501A1 (CYP1A1) has been considered to play a central role in the activation step, which is essential for the formation of DNA adducts. This enzyme is strongly induced by many different chemical agents, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which binds to the aryl hydrocarbon receptor (AhR). Therefore, AhR activators are suspected to have the potential to aggravate the toxicity of BaP through the induction of CYP1A1. Besides, CYP1A1 inhibitors, including its substrates, are estimated to have preventive effects against BaP toxicity. However, strangely, increased hepatic BaP–DNA adduct levels have been reported in Cyp1a1 knockout mice. Moreover, numerous reports describe that concomitant treatment of AhR activators reduced BaP–DNA adduct formation. In an experiment using several human cell lines, TCDD had diverse modulatory effects on BaP–DNA adducts, both enhancing and inhibiting their formation. In this review, we focus on the factors that could influence the BaP–DNA adduct formation. To interpret these complicated outcomes, we propose a hypothesis that CYP1A1 is a key enzyme for both generation and reduction of (±)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), the major carcinogenic intermediate of BaP. Conversely, CYP1B1 is thought to contribute only to the metabolic activation of BaP related to carcinogenesis.