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Chemical Research in Toxicology Apr 2022The gut microbiome is a key contributor to xenobiotic metabolism. Polycyclic aromatic hydrocarbons (PAHs) are an abundant class of environmental contaminants that have...
The gut microbiome is a key contributor to xenobiotic metabolism. Polycyclic aromatic hydrocarbons (PAHs) are an abundant class of environmental contaminants that have varying levels of carcinogenicity depending on their individual structures. Little is known about how the gut microbiome affects the rates of PAH metabolism. This study sought to determine the role that the gut microbiome has in determining the various aspects of metabolism in the liver, before and after exposure to two structurally different PAHs, benzo[]pyrene and 1-nitropyrene. Following exposures, the metabolic rates of PAH metabolism were measured, and activity-based protein profiling was performed. We observed differences in PAH metabolism rates between germ-free and conventional mice under both unexposed and exposed conditions. Our activity-based protein profiling (ABPP) analysis showed that, under unexposed conditions, there were only minor differences in total P450 activity in germ-free mice relative to conventional mice. However, we observed distinct activity profiles in response to corn oil vehicle and PAH treatment, primarily in the case of 1-NP treatment. This study revealed that the repertoire of active P450s in the liver is impacted by the presence of the gut microbiome, which modifies PAH metabolism in a substrate-specific fashion.
Topics: Animals; Benzo(a)pyrene; Gastrointestinal Microbiome; Mice; Polycyclic Aromatic Hydrocarbons; Pyrenes; Xenobiotics
PubMed: 35347982
DOI: 10.1021/acs.chemrestox.1c00360 -
Ecotoxicology and Environmental Safety Dec 2022In a previous study our group identified Bacillus sp. strain M1 as an efficient decomposer of high molecular weight-polycyclic aromatic hydrocarbons (HMW-PAHs)....
In a previous study our group identified Bacillus sp. strain M1 as an efficient decomposer of high molecular weight-polycyclic aromatic hydrocarbons (HMW-PAHs). Interestingly, its removal efficiency for benzo[a]pyrene (BaP) was nearly double that of pyrene (Pyr), which was the reverse of what is reported for most other species. Here we compared the differential steps of biosorption, transmembrane transport and biodegradation of Pyr and BaP by strain M1 in order to assist in targeted selection of dominant strains and their degradation efficiency in the remediation of these two HMW-PAHs. The overall biosorption efficiency for BaP was 19% higher than that for Pyr, and the time needed to reach BaP peak adsorption efficiency was 4 days shorter than for Pyr. Transmembrane transport of the PAHs was compared in presence of sodium azide which inhibits ATP synthesis and metabolism. This indicated that both Pyr and BaP entered the cells by the same means of passive transport. Biodegradation of Pyr and BaP did not differ in the early stage of culture, but around days 5-7, the biodegradation efficiency of BaP was significantly (30-61%) higher than that of Pyr. Key enzymes involved in these processes were identified and their activity differed, with intracellular gentisate 1,2-dioxygenase and extracellular polyphenol oxidase as likely candidates to be involved in BaP degradation, while intracellular catechol-1,2- dioxygenase and salicylate hydroxylase are more likely involved in Pyr degradation. These results provide new insights for sustainable environmental remediation of pyrene and benzo(a)pyrene by these bacteria.
Topics: Benzo(a)pyrene; Bacillus; Adsorption; Pyrenes; Polycyclic Aromatic Hydrocarbons
PubMed: 36436257
DOI: 10.1016/j.ecoenv.2022.114328 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Jun 2020To analyze the effect of benzopyrene on the decrease of dopaminergic neurons, and the increase and aggregation of α-synuclein, which are the pathological features of...
OBJECTIVE
To analyze the effect of benzopyrene on the decrease of dopaminergic neurons, and the increase and aggregation of α-synuclein, which are the pathological features of Parkinson's disease, and to explore its possible mechanisms.
METHODS
Eight-month-old transgenic mice with human gene were randomly divided into a BaP-exposed group and a control group. BaP and solvent corn oil were injected intraperitoneally to BaP-exposed group and control group respectively, once a day for 60 days. The motor dysfunction of mice was tested by rotarod test. The effects of BaP on the decrease of dopaminergic neurons and increase and aggregation of α-synuclein were observed by immunohistochemistry and Western blot experiments respectively, and the expression of related mRNA was detected by quantitative real-time PCR (qRT-PCR). Twenty genes were tested in the study, mainly related to neurotransmitter transporter (2 genes), neurotransmitter receptor function (10 genes), cellular autophagy (5 genes), and α-synuclein aggregation and degradation (3 genes).
RESULTS
After BaP exposure, the movement time of the mice in the rotarod test was significantly reduced (<0.05). The substantia nigra dopami-nergic neurons in the mice were significantly reduced, which was 62% of the control group (<0.05), and the expression of α-synuclein in the midbrain increased, which was 1.36 times that of the control group (<0.05). After BaP exposure, mRNA expressions of 14 genes in the midbrain of the mice were significantly down-regulated (<0.05). Alpha-synuclein degradation and cell autophagy (5 genes), neuron transporters (2 genes), and neurotransmitter receptor functions (5 genes) were involved. The expression of one gene, , was significantly up-regulated (<0.01), which was related to α-synuclein aggregation.
CONCLUSION
BaP exposure not only inhibited function of neurotransmitter receptor and dopamine transporter, but also interfered cell autophagy, thereby hindering the degradation of α-synuclein, which could lead to decrease of dopaminergic neurons in substantia nigra and increase and aggregation of α-synuclein in midbrain, as the significant pathology of Parkinson's disease. Therefore, BaP exposure may increase the risk of Parkinson's disease.
Topics: Animals; Benzo(a)pyrene; Brain; Dopamine; Dopaminergic Neurons; Humans; Mice; alpha-Synuclein
PubMed: 32541975
DOI: 10.19723/j.issn.1671-167X.2020.03.007 -
Experimental Biology and Medicine... Aug 2016Tobacco-sourced carcinogen including benzopyrene (B[a]P) in lung cancer metastasis has not been fully reported. In this study, lung carcinoma A549 cell line was used to...
Tobacco-sourced carcinogen including benzopyrene (B[a]P) in lung cancer metastasis has not been fully reported. In this study, lung carcinoma A549 cell line was used to investigate the potential roles of tobacco-sourced B[a]P on cell metastasis and invasion and to assess its underlying mechanism. Effects of tobacco-sourced carcinogen on A549 cell proliferation, metastasis, and invasion were analyzed using MTT assay, Transwell assay, and scratch method, respectively. The effects of tobacco-sourced carcinogen on cytokines and chemokines secretion were detected using enzyme-linked immunosorbent assay. Moreover, correlation between inflammatory factor expression and cancer cell migration and invasion was assessed using siRNA-mediated gene silencing. Data showed that both B[a]P and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone either at high or low dose performed no significant difference on A549 cell proliferation with time increasing. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone performed no significant difference on A549 cell migration and invasion while B[a]P significantly increased A549 cell migration and invasion compared to the control group (P < 0.05). Consequently, except for IL-6, IL-8, CCL-2, and CCL-3, secretions were significantly increased by B[a]P treatment compared to the control (P < 0.05). Furthermore, when CCL-2 and CCL-3 were silenced, the migrated and invasive A549 cells were significantly decreased compared to the control, respectively (P < 0.05), while silenced IL-8 drastically decreased the migrated and invasive cells compared to the control (P < 0.01). Taken together, this study illustrated that there may be significant correlation between smoking and lung cancer metastasis. B[a]P maybe an excellent contributor for lung cancer metastasis through up-regulating IL-8, CCL-2, and CCL-3 expression.
Topics: A549 Cells; Benzopyrenes; Cell Line, Tumor; Cell Movement; Cell Proliferation; Chemokine CCL2; Chemokine CCL3; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation, Neoplastic; Humans; Interleukin-8; Neoplasm Invasiveness; Neoplasm Metastasis; Nitrosamines; RNA Interference; Nicotiana; Up-Regulation
PubMed: 27075927
DOI: 10.1177/1535370216644530 -
British Journal of Cancer Aug 1998Benzo(a)pyrene and benzene are human carcinogens. The metabolic activation of these compounds into ultimate mutagenic and carcinogenic metabolites is prerequisite for...
Benzo(a)pyrene and benzene are human carcinogens. The metabolic activation of these compounds into ultimate mutagenic and carcinogenic metabolites is prerequisite for their carcinogenic effects. In this report, the mutagenicity and carcinogenicity of hydroquinones of benzo(a)pyrene and benzene was investigated to address two important questions: (1) do hydroquinones contribute to benzo(a)pyrene and benzene carcinogenicity; and (2) how safe is it to increase the levels of NAD(P)H:quinone oxidoreductase 1 (NQO1), a key enzyme in the generation of hydroquinone. The supF tRNA of the plasmid pSP189 was used as the mutational target in a cell-free and Chinese hamster ovary (CHO) cell system to study hydroquinone mutagenicity. RNA and protein-free pSP189 DNA was incubated in a cell-free system with benzo(a)pyrene-3,6-quinone and purified NQO1 or with benzoquinone hydroquinone to generate adducted pSP189 DNA. The adducted pSP189 DNA was transfected in human embryonic kidney cells Ad293. In the CHO cell system, monolayer cultures of CHO cells and CHO cells overexpressing NQO1 or P450 reductase were transfected with pSP189 vector DNA, treated with benzo(a)pyrene-3,6-quinone. The adducted and replicated pSP189 DNA was rescued from transfected Ad293 (cell-free system) and CHO cells (CHO cell system), digested with the restriction enzyme Dpn1 to remove unreplicated DNA followed by transformation in Escherichia coli MBM7070. The mutant colonies [white/pale blue on 5-bromo-4-chloro-3-indolyl beta-D-galactoside/isopropyl beta-D-thiogalactoside (X-gal/IPTG) plates] were selected, regrown and analysed by DNA sequencing. Mutagenesis experiments demonstrated that hydroquinones cause sequence-specific frameshift mutations involving deletion of a single cytosine from the DNA sequence 5'-172-CCCCC176-3' or a single guanosine from the complementary strand sequence 5'-GGGGG-3' in the supF tRNA gene. This mutation was specific to the hydroquinones, as it was not observed with quinones and other components of the redox cycling (semiquinones and reactive oxygen species). Exposure of BALBc/3T3 cells to hydroquinones resulted in cellular transformation leading to the loss of contact inhibition and regulation of cell growth. The transformation efficiency of BALBc/3T3 cells exposed to hydroquinones was significantly increased by the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), indicating that hydroquinones are excellent initiators that require additional co-carcinogens or promoters to exert an effect. The hydroquinone + TPA as well as hydroquinone-transformed BALBc/3T3 cells, when injected s.c. in severe combined immunodeficient (SCID) mice, produced tumours at 100% frequency. These results establish that hydroquinones lead to mutagenicity and carcinogenicity.
Topics: 3T3 Cells; Animals; Benzene; Benzopyrenes; CHO Cells; Carcinogens; Cell Transformation, Neoplastic; Cells, Cultured; Cricetinae; Frameshift Mutation; Genes, p53; Genes, ras; Humans; Hydroquinones; Mice; Mice, Inbred BALB C; Mice, SCID; Mutagens; NAD(P)H Dehydrogenase (Quinone); Neoplasm Transplantation; Skin Neoplasms; Transfection
PubMed: 9703276
DOI: 10.1038/bjc.1998.492 -
The Journal of Toxicological Sciences Jun 2015Toxic and harmful factors co-exist in the environment; these factors often interact to induce combined toxicity, which is the main focus of toxicological research....
Toxic and harmful factors co-exist in the environment; these factors often interact to induce combined toxicity, which is the main focus of toxicological research. Furthermore, a large number of studies have shown that aluminum (Al) and benzo[a]pyrene (BaP) are neurotoxic and target the central nervous system to cause neuronal apoptosis. Because we are exposed to both Al and BaP in the air, water, food, and even medicine, the combined effects of these agents in humans must be examined. The present study examines the ability of Al and BaP co-exposure to intensify neuronal apoptosis. The primary neurons of newborn rats were cultured for 5 days, and cells from the same batch that were growing well were selected and assigned to the blank control group, the solvent control group (DMSO+S9+maltol), BaP groups (10, 40 μmol/L), Al (mal)3 groups (50, 100, 400 μmol/L) and co-exposure groups with different combinations of BaP and Al (mal)3. The cell viabilities indicated that 10 μM BaP or 50 μM Al (mal)3 was mildly toxic, and we selected 10 μM BaP+50 μM Al (mal)3 for subsequent co-exposure experiments. The morphological characteristics of cell apoptosis were much more obvious in the co-exposure group than in the Al-exposed cells or the BaP-exposed cells, as observed with a transmission electron microscope and a fluorescence inverted microscope. The apoptotic rates and caspase-3 activity quantitatively significantly differed between the co-exposure and Al-exposure groups, while the BaP-exposure group did not significantly differ from the control group. These results indicate that Al and BaP co-exposure exert synergistic effects on neuronal cell apoptosis.
Topics: Aluminum Compounds; Animals; Apoptosis; Benzopyrenes; Caspase 3; Cells, Cultured; Drug Synergism; Environmental Pollutants; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Neurons; Rats, Sprague-Dawley
PubMed: 25971159
DOI: 10.2131/jts.40.365 -
Environmental Health Perspectives Dec 1981Benzo(a)pyrene(BaP) originating from fossil fuel and other organic combustion processes is largely adsorbed on fine particulate and hence is a widespread atmospheric... (Review)
Review
Benzo(a)pyrene(BaP) originating from fossil fuel and other organic combustion processes is largely adsorbed on fine particulate and hence is a widespread atmospheric pollutant. Available emissions and air quality data are based on the total weight of particulate matter without reference to size and give little information on trends and concentrations of fine particulate BaP. Greater reliance on coal, synfuels and diesel fuel for energy production and transportation will significantly increase ambient levels of BaP. Because of the particulate size, BaP is substantially deposited in the lower lung and readily eluted into surrounding tissue. After elution in the lung, BaP is metabolically activated to its electrophilic, carcinogenic from by a complex enzyme system whose activity is increased by prior exposure to air pollutants, cigarette smoke and certain drugs. The resultant diol epoxide metabolite has been shown to bind covalently with the DNA of the lung. In experimental animals, BaP is a potent initiating carcinogen whose action is enhanced by sulfur dioxide, promoting agents and carrier fine particles. The effect of small, divided doses of BaP has been shown to be greater than that of a single high dose; no threshold has been established. Epidemiological studies show that mixtures containing BaP (such as urban air, industrial emissions and cigarette smoke) are carcinogenic and may interact synergistically. Occupational studies indicate that the action of BaP-containing mixtures is enhanced in the presence of SO2. However, quantitative risk assessment for BaP is precluded by problems in extrapolating to the general population from small-scale animal studies; uncertainties in findings of epidemiology; and imprecise exposure data. Existing stationary and mobile controls preferentially remove coarse particulate matter and are inefficient collectors of the particulate BaP. In the current absence of health and environmental standards for BaP, there is little incentive to control BaP emissions. BaP meets the criteria for regulation under the Clean Air Act; however, no such BaP standards have yet been proposed.
Topics: Air Pollutants; Air Pollution; Animals; Benzo(a)pyrene; Benzopyrenes; Carcinogens, Environmental; DNA; Epidemiology; Humans; Mixed Function Oxygenases; Particle Size; United States
PubMed: 6277615
DOI: 10.1289/ehp.8142163 -
Toxicological Sciences : An Official... Sep 2013Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants generated during combustion. Dibenzo[def,p]chrysene (DBC) is a high molecular weight...
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants generated during combustion. Dibenzo[def,p]chrysene (DBC) is a high molecular weight PAH classified as a 2B carcinogen by the International Agency for Research on Cancer. DBC crosses the placenta in exposed mice, causing carcinogenicity in offspring. We present pharmacokinetic data of DBC in pregnant and nonpregnant mice. Pregnant (gestational day 17) and nonpregnant female B6129SF1/J mice were exposed to 15mg/kg DBC by oral gavage. Subgroups of mice were sacrificed up to 48h postdosing, and blood, excreta, and tissues were analyzed for DBC and its major diol and tetrol metabolites. Elevated maximum concentrations and areas under the curve of DBC and its metabolites were observed in blood and tissues of pregnant animals compared with naïve mice. Using a physiologically based pharmacokinetic (PBPK) model, we found observed differences in pharmacokinetics could not be attributed solely to changes in tissue volumes and blood flows that occur during pregnancy. Measurement of enzyme activity in naïve and pregnant mice by activity-based protein profiling indicated a 2- to 10-fold reduction in activities of many of the enzymes relevant to PAH metabolism. Incorporating this reduction into the PBPK model improved model predictions. Concentrations of DBC in fetuses were one to two orders of magnitude below maternal blood concentrations, whereas metabolite concentrations closely resembled those observed in maternal blood.
Topics: Animals; Aryl Hydrocarbon Hydroxylases; Benzopyrenes; Carcinogens; Cytochrome P-450 CYP1B1; Female; Male; Mice; Models, Biological; Pregnancy; Pregnancy, Animal; Tissue Distribution
PubMed: 23744095
DOI: 10.1093/toxsci/kft124 -
Chemical Research in Toxicology Nov 2022In a series of previous studies we reported that black raspberry (BRB) powder inhibits dibenzo[,]pyrene (DBP)-induced DNA damage, mutagenesis, and oral squamous cell...
In a series of previous studies we reported that black raspberry (BRB) powder inhibits dibenzo[,]pyrene (DBP)-induced DNA damage, mutagenesis, and oral squamous cell carcinoma (OSCC) development in mice. In the present study, using human oral leukoplakia (MSK-Leuk1) and squamous cell carcinoma (SCC1483) cells, we tested the hypothesis that BRB extract (BRBE) will enhance the synthesis of glutathione (GSH) and in turn increase GSH conjugation of the fjord-region DBP diol epoxide (DBPDE) derived from DBP leading to inhibition of DBP-induced DNA damage. The syntheses of DBPDE-GSH conjugate, DBPDE-dA adduct, and the corresponding isotope-labeled internal standards were performed; LC-MS/MS methods were used for their quantification. BRBE significantly ( < 0.05) increased cellular GSH by 31% and 13% at 6 and 24 h, respectively, in OSCC cells; in MSK-LeuK1 cells, the levels of GSH significantly ( < 0.05) increased by 55% and 22%, at 1 and 6 h. Since BRBE significantly enhanced the synthesis of GSH in both cell types, subsequent experiments were performed in MSK-Leuk1 cells. Western blot analysis was performed to determine the types of proteins involved in the synthesis of GSH. BRBE significantly ( < 0.05) increased the protein expression (2.5-fold) of the glutamate-cysteine ligase catalytic subunit (GCLC) but had no effect on the glutamate-cysteine ligase modifier subunit (GCLM) and glutathione synthetase (GSS). LC-MS/MS analysis showed that pretreatment of cells with BRBE followed by DBPDE significantly ( < 0.05) increased the levels of DBPDE-GSH conjugate (2.5-fold) and decreased DNA damage by 74% measured by assessing levels of DBPDE-dA adduct formation. Collectively, the results of this study clearly support our hypothesis, and the LC-MS/MS methods developed in the present study will be highly useful in testing the same hypothesis initially in our mouse model and ultimately in smokers.
Topics: Humans; Mice; Animals; Carcinogens; Chrysenes; Rubus; Benzopyrenes; Epoxy Compounds; Nicotiana; Glutamate-Cysteine Ligase; DNA Adducts; Carcinoma, Squamous Cell; Chromatography, Liquid; Estuaries; Mouth Neoplasms; Tandem Mass Spectrometry; Glutathione; Plant Extracts
PubMed: 36260657
DOI: 10.1021/acs.chemrestox.2c00246 -
PloS One 2017Microbial interactions are ubiquitous in nature, and are equally as relevant to human wellbeing as the identities of the interacting microbes. However, microbial...
Microbial interactions are ubiquitous in nature, and are equally as relevant to human wellbeing as the identities of the interacting microbes. However, microbial interactions are difficult to measure and characterize. Furthermore, there is growing evidence that they are not fixed, but dependent on environmental context. We present a novel workflow for inferring microbial interactions that integrates semi-automated image analysis with a colony stamping mechanism, with the overall effect of improving throughput and reproducibility of colony interaction assays. We apply our approach to infer interactions among bacterial species associated with the normal lung microbiome, and how those interactions are altered by the presence of benzo[a]pyrene, a carcinogenic compound found in cigarettes. We found that the presence of this single compound changed the interaction network, demonstrating that microbial interactions are indeed dynamic and responsive to local chemical context.
Topics: Benzo(a)pyrene; Benzopyrenes; Carcinogens; Cell Culture Techniques; Electronic Data Processing; Haemophilus; Humans; Image Processing, Computer-Assisted; Lung; Microbial Interactions; Microbiota; Microscopy; Pseudomonas aeruginosa; Staphylococcus aureus
PubMed: 28319121
DOI: 10.1371/journal.pone.0164919