Benzo[g,h,i]perylene synergistically transactivates benzo[a]pyrene-induced CYP1A1 gene expression by aryl hydrocarbon receptor pathway

Modeling PAH Mixture Interactions in a Human In Vitro Organotypic Respiratory Model

One of the most significant challenges in human health risk assessment is to evaluate hazards from exposure to environmental chemical mixtures. Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous contaminants typically found as mixtures in gaseous and particulate phases in ambient air pollution associated with petrochemicals from Superfund sites and the burning of fossil fuels. However, little is understood about how PAHs in mixtures contribute to toxicity in lung cells. To investigate mixture interactions and component additivity from environmentally relevant PAHs, two synthetic mixtures were created from PAHs identified in passive air samplers at a legacy creosote site impacted by wildfires. The primary human bronchial epithelial cells differentiated at the air-liquid interface were treated with PAH mixtures at environmentally relevant proportions and evaluated for the differential expression of transcriptional biomarkers related to xenobiotic metabolism, oxidative stress response, barrier integrity, and DNA damage response. Component additivity was evaluated across all endpoints using two independent action (IA) models with and without the scaling of components by toxic equivalence factors. Both IA models exhibited trends that were unlike the observed mixture response and generally underestimated the toxicity across dose suggesting the potential for non-additive interactions of components. Overall, this study provides an example of the usefulness of mixture toxicity assessment with the currently available methods while demonstrating the need for more complex yet interpretable mixture response evaluation methods for environmental samples.

The role of N6-methyladenosine methylation in PAHs-induced cancers

Polycyclic aromatic hydrocarbons (PAHs), which are a wide range of environmental toxicants, may act on humans through inhalation, ingestion, and skin contact, resulting in a range of toxic reactions. Epidemiological studies showed that long-term exposure to PAHs in the occupational and living environment results in a substantial rise in the incidence rate of many cancers in the population, so the prevention and treatment of these diseases have become a major worldwide public health problem. N6-methyladenosine (m6A) modification greatly affects the metabolism of RNA and is implicated in the etiopathogenesis of many kinds of diseases. In addition, m6A-binding proteins have an important role in disease development. The abnormal expression of these can cause the malignant proliferation, migration, invasion, and metastasis of cancers. Furthermore, a growing number of studies revealed that environmental toxicants are one of the cancer risk factors and are related to m6A modifications. Exposure to environmental toxicants can alter the methylation level of m6A and the expression of the m6A-binding protein, thus promoting the occurrence and development of cancers through diverse mechanisms. m6A may serve as a biomarker for early environmental exposure. Through the study of m6A, we can find the health injury early, thus providing a new sight for preventing and curing environmental health-related diseases.

Benzo[ghi]perylene induces cellular dormancy signaling and endoplasmic reticulum stress in NL-20 human bronchial epithelial cells

Benzo[ghi]perylene (BghiP) is produced by the incomplete combustion of gasoline and it is a marker of high vehicular flow in big cities. Nowadays, it is known that BghiP functions as ligand for the aryl hydrocarbon receptor (AhR), which can cause several molecular responses. For this reason, the aim of the present study was to assess the in vitro effects of the exposure to BghiP, specifically, the induction of cellular dormancy and endoplasmic reticulum stress (ER stress) in NL-20 human cells. Our results proved that a 24 h exposure of BghiP, increased the expression of NR2F1 (p < 0.05). NR2F1 is the main activator of cell dormancy, therefore, we analyzed the expression of its target genes SOX9 and p27 showing an increase of the transcripts (p < 0.05), suggesting a pathway that could produce a cell cycle arrest. Interestingly, this effect was only observed with BghiP exposure, and not with a classic AhR ligand: benzo[a]pyrene. Moreover, in the presence of the AhR antagonist, CH223191, or when the expression of AhR was knock-down using dsiRNAs, the cellular dormancy signaling pathway was blocked. Morphological and ultrastructure analysis demonstrated that BghiP also induces ER stress, characterized by the dilated ER cisternae and the overexpression of PERK and CHOP genes (p < 0.05). Moreover, the halt of cell proliferation and the ER stress are both associated to the increase of pro-inflammatory cytokines (IL-6 and IL-8) and the cell survival in response to microenvironmental cues. These responses induced by BghiP on bronchial cells open new horizons on the research of other biological effects induced by environmental pollutants.

Cytochrome P450 1A mRNA in the Gambusia affinis and Response to Several PAHs

Cytochrome P4501A (CYP1A) has been used as a specific biomarker for monitoring water contamination such as PAHs, PCBs and dioxins. In the present study, the cyp1a gene of Gambusia affinis was cloned and sequenced and their expressions under PAHs exposure were characterized. The newly identified cyp1a encodes a protein with 521 amino acids that shared 96-80% identity with other Cyprinodontiformes fishes. RT-PCR analysis revealed that the basal mRNA level of cyp1a was highly expressed in liver and intestine. The expression level of cyp1a was significantly induced by exposure to 100 μg/L 3, 4-Benzopyrene (BaP) for 5 days in the muscle, testis, brain, liver and intestine of adult male fish. Except in the testis, the induced mRNA level of cyp1a ultimately decreased after prolonging the exposure time to 25 days. As for testis, the induced mRNA level of cyp1a was maintained at a high level during the entire exposure time under 100 μg/L BaP exposure. Furthermore, the expression of cyp1a increased with exposure time under a relatively low exposure concentrations 1 μg/L. Regarding the effects of other PAHs, D(a,h)A, BbF, and BaA showed a statistically significant effect of induction on mRNA level of cyp1a in the muscle, testis, brain, liver and intestine.

Phytochemical Investigation on Volatile Compositions and Methoxylated Flavonoids of Agrostis gigantea Roth

In this study, methoxylated flavonoids and volatile constitutions of Agrostis gigantea Roth (Poaceae) were investigated for the first time. The flavonoids were identified by spectroscopic methods (1H-NMR, 13C-NMR, COSY, NOSEY, TCOSY, and HMBC). The volatile constitutions of aerial parts and seeds were analyzed by gas chromatography-mass spectrometry (GC-MS). Two methoxylated flavonoids, luteolin 5-methyl ether (1), and cirsilineol (2) were isolated from the aerial parts of this plant. According to the GC-MS data the main constitutions of these volatile oils belong to the simple phenolic category which include coniferyl alcohol (18.80%) and eugenol (12.19%) in aerial parts and seeds, respectively. By using the computer- aided molecular modeling approaches, the binding affinity of these compounds was predicted in the catalytic domains of aryl hydrocarbon receptor (AhR). These two isolated flavonoids were investigated in-vitro for their inhibitory activity on 4T1 breast carcinoma cells. It was predicted that these compounds could be well-matched in aryl hydrocarbon receptor (3H82) active site, but based on the in-vitro assay, the IC50 values on cytotoxicity were 428.24 ±3.21 and 412.7±3.02 μg/mL for luteolin 5-methyl ether and cirsilineol, respectively. Thus, it can be concluded that these flavonoids exhibit low cytotoxicity against 4T1 breast carcinoma cell line.

Melatonin defends mouse oocyte quality from benzo[ghi]perylene-induced deterioration

Benzo[ghi]perylene (B[ghi]P) is a polycyclic aromatic hydrocarbon widely found in haze. Long-term exposure to humans or animals can cause serious damage to the respiratory system. Melatonin is an endogenous natural hormone synthesized and released by the pineal gland. In this study, we investigated the effects of melatonin on in vitro cultured B[ghi]P-exposed mouse oocytes and the protective roles of melatonin. Our data indicate that B[ghi]P exposure leads to meiotic maturation arrest and reduced ability of sperm binding and parthenogenetic activation. Also, B[ghi]P exposure disrupts actin filament dynamics, spindle assembly, and kinetochore-microtubule attachment stability, which results in oocyte aneuploidy. Simultaneously, B[ghi]P exposure disturbs the distribution of mitochondria, increases the level of oxidative stress, and induces apoptosis of oocytes. Whereas all of these toxic effects of B[ghi]P can be restored after melatonin supplement. In conclusion, our findings validate that melatonin has a certain protective effect on preventing the reduced oocyte quality caused by B[ghi]P exposure during meiotic maturation in mouse oocytes.

Development and Uses of Offline and Web-Searchable Metabolism Databases - The Case of Benzo[a]pyrene

BACKGROUND

The present work describes development of offline and web-searchable metabolism databases for drugs, other chemicals, and physiological compounds using human and model species, prompted by the large amount of data published after year 1990. The intent was to provide a rapid and accurate approach to published data to be applied both in science and to assist therapy.

METHODS

Searches for the data were done using the Pub Med database, accessing the Medline database of references and abstracts. In addition, data presented at scientific conferences (e.g., ISSX conferences) are included covering the publishing period beginning with the year 1976.

RESULTS

Application of the data is illustrated by the properties of benzo[a]pyrene (B[a]P) and its metabolites. Analysis show higher activity of P450 1A1 for activation of the (-)- isomer of trans-B[a]P-7,8-diol, while P4501B1 exerts higher activity for the (+)- isomer. P450 1A2 showed equally low activity in the metabolic activation of both isomers.

CONCLUSION

The information collected in the databases is applicable in prediction of metabolic drug-drug and/or drug-chemical interactions in clinical and environmental studies. The data on the metabolism of searched compound (exemplified by benzo[a]pyrene and its metabolites) also indicate toxicological properties of the products of specific reactions. The offline and web-searchable databases had wide range of applications (e.g. computer assisted drug design and development, optimization of clinical therapy, toxicological applications) and adjustment in everyday life styles.

Cytochrome P450 1A1 (CYP1A1) Catalyzes Lipid Peroxidation of Oleic Acid-Induced HepG2 Cells

Nonalcoholic fatty liver disease (NAFLD) is a chronic hepatic disease associated with excessive accumulation of lipids in hepatocytes. As the disease progresses, oxidative stress plays a pivotal role in the development of hepatic lipid peroxidation. Cytochrome P450 1A1 (CYP1A1), a subtype of the cytochrome P450 family, has been shown to be a vital modulator in production of reactive oxygen species. However, the exact role of CYP1A1 in NAFLD is still unclear. The aim of this study was to investigate the effects of CYP1A1 on lipid peroxidation in oleic acid (OA)-treated human hepatoma cells (HepG2). We found that the expression of CYP1A1 is elevated in OA-stimulated HepG2 cells. The results of siRNA transfection analysis indicated that CYP1A1-siRNA inhibited the lipid peroxidation in OA-treated HepG2 cells. Additionally, compared with siRNA-transfected and benzo[a]pyrene (BaP)-OA-induced HepG2 cells, overexpression of CYP1A1 by BaP further accelerated the lipid peroxidation in OA-treated HepG2 cells. These observations reveal a regulatory role of CYP1A1 in liver lipid peroxidation and imply CYP1A1 as a potential therapeutic target.

An in vitro cytotoxicities comparison of 16 priority polycyclic aromatic hydrocarbons in human pulmonary alveolar epithelial cells HPAEpiC

In present study, we compared for the first time the cytotoxicities of the 16 priority polycyclic aromatic hydrocarbons (PAHs) in human pulmonary alveolar epithelial cells HPAEpiC. Moreover, we examined the effects of each PAH on oxidative stress (SOD, GSH, and ROS), cell viability, extracellular LDH, and apoptosis. The 16 priority PAHs were classified into four levels of cytotoxicity: (1) high cytotoxicity, BkF, BaP, and DBA; (2) moderate cytotoxicity, BbF, IND, BghiP, BaA, and CHR; (3) low cytotoxicity, PA, FL, and Pyr; and (4) mild cytotoxicity, Nap, AcPy, Acp, Flu, and Ant. Most of the PAHs showed benzene-ring-related cytotoxicity, except PA with 3-ring structure, cytotoxicity of which is similar to those of FL and Pyr with 4-ring structure. Results indicated the need for more studies on DBA, IND, and BghiP, among others, which are rarely investigated. PA, FL, and Pyr with little carcinogenicity should also be evaluated. This study will provide useful references for studies on the effects of PAHs on different cells or animal models.

Synergistic and antagonistic interactions of binary mixtures of polycyclic aromatic hydrocarbons in the upregulation of CYP1 activity and mRNA levels in precision-cut rat liver slices

The current studies investigate whether synergistic or antagonistic interactions in the upregulation of CYP1 activity occur in binary mixtures of polycyclic aromatic hydrocarbons (PAHs) involving benzo[a]pyrene and five other structurally diverse PAHs of varying carcinogenic activity. Precision-cut rat liver slices were incubated with benzo[a]pyrene alone or in combination with a range of concentrations of a second PAH, and ethoxyresorufin O-deethylase, CYP1A1 and CYP1B1 mRNA levels determined. Concurrent incubation of benzo[a]pyrene with either dibenzo[a,h]anthracene or fluoranthene in liver slices led to a synergistic interaction, at least at low concentrations, in that ethoxyresorufin O-deethylase activity was statistically higher than the added effects when the slices were incubated with the individual compounds. In contrast, benzo[b]fluoranthene and, at high doses only, dibenzo[a,l]pyrene gave rise to antagonism, whereas 1-methylphenanthrene had no effect at all concentrations studied. When CYP1A1 mRNA levels were monitored, benzo[b]fluoranthene gave rise to an antagonistic response when incubated with benzo[a]pyrene, whereas all other compounds displayed synergism, with 1-methylphenathrene being the least effective. A similar picture emerged when CYP1B1 mRNA levels were determined, though the effects were less pronounced. In conclusion, it has been demonstrated that the benzo[a]pyrene-mediated upregulation of CYP1, at the mRNA and activity levels, is synergistically and antagonistically modulated by other PAHs. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 764-775, 2017.

Bioaccumulation and detoxification responses in the scallop Chlamys farreri exposed to tetrabromobisphenol A (TBBPA)

Tetrabromobisphenol A (TBBPA) is currently the most widely used brominated flame retardant (BFR). In this study, the bioaccumulation of TBBPA and its consequent detoxification responses were examined in the scallop Chlamys farreri over 10 days' exposure. Chemical analysis showed that C. farreri absorbed TBBPA rapidly and an approximate steady state was achieved within 6 days. The mRNA expression levels of three important genes involved in aryl hydrocarbon receptor (AhR) pathway were down-regulated upon TBBPA exposure. Both CYP3A and CYP4 showed time-dependent responses to TBBPA exposure. Glutathione-S-transferase (GST) activity and gene expression level, and UDP-glucuronosyltransferase (UGT) activity were increased in time- and dose-dependent manners, confirming their role in the phase II metabolism of TBBPA. The TBBPA-elicited down-regulation of the P-glycoprotein (Pgp) gene was observed in all treatments. This study provides a preliminary basis for studying TBBPA detoxification mechanisms of marine bivalves.

Deep sequencing of the scallop Chlamys farreri transcriptome response to tetrabromobisphenol A (TBBPA) stress

Tetrabromobisphenol-A (TBBPA) is currently the most widely used brominated flame retardant (BFR) and has been proven to have a very high toxicity to aquatic organisms including bivalves. However, molecular responses to TBBPA in bivalve remain largely unknown. Novel high-throughput deep sequencing technology has been a powerful tool for looking at molecular responses to toxicological stressors in organisms. Using Illumina's digital gene expression (DGE) system, we investigated TBBPA-induced transcriptome response in the digestive gland tissue of scallop Chlamys farreri. In total, 173 and 266 genes were identified as significantly up- or down-regulated, respectively. Functional analysis based on gene ontology (GO) classification system and Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed that TBBPA significantly altered the expression of genes involved in stress response, detoxification, antioxidation, and innate immunity which were extensively discussed. In particular, evidence for the endocrine disrupting effect of TBBPA on bivalve was first obtained in this study. Quantitative real-time PCR was performed to ascertain the mRNA expression of several genes identified by the DGE analysis. The results of this study may serve as a basis for future research on molecular mechanism of toxic effects of TBBPA on marine bivalves.

Interactions between polycyclic aromatic hydrocarbons in complex mixtures and implications for cancer risk assessment

In this review we discuss the effects of exposure to complex PAH mixtures in vitro and in vivo on mechanisms related to carcinogenesis. Of particular concern regarding exposure to complex PAH mixtures is how interactions between different constituents can affect the carcinogenic response and how these might be included in risk assessment. Overall the findings suggest that the responses resulting from exposure to complex PAH mixtures is varied and complicated. More- and less-than additive effects on bioactivation and DNA damage formation have been observed depending on the various mixtures studied, and equally dependent on the different test systems that are used. Furthermore, the findings show that the commonly used biological end-point of DNA damage formation is insufficient for studying mixture effects. At present the assessment of the risk of exposure to complex PAH mixtures involves comparison to individual compounds using either a surrogate or a component-based potency approach. We discuss how future risk assessment strategies for complex PAH mixtures should be based around whole mixture assessment in order to account for interaction effects. Inherent to this is the need to incorporate different experimental approaches using robust and sensitive biological endpoints. Furthermore, the emphasis on future research should be placed on studying real life mixtures that better represent the complex PAH mixtures that humans are exposed to.

Polymorphisms in the human cytochrome P450 and arylamine N-acetyltransferase: susceptibility to head and neck cancers

The occurrence of head and neck cancer (HNC) is associated with smoking and alcohol drinking. Tobacco smoking exposes smokers to a series of carcinogenic chemicals. Cytochrome P450 enzymes (CYP450s), such as CYP1A1, CYP1B1, and CYP2D6, usually metabolize carcinogens to their inactive derivatives, but they occasionally convert the chemicals to more potent carcinogens. In addition, via CYP450 (CYP2E1) oxidase, alcohol is metabolized to acetaldehyde, a highly toxic compound, which plays an important role in carcinogenesis. Furthermore, two N-acetyltransferase isozymes (NATs), NAT1 and NAT2, are polymorphic and catalyze both N-acetylation and O-acetylation of aromatic and heterocyclic amine carcinogens. Genetic polymorphisms are associated with a number of enzymes involved in the metabolism of carcinogens important in the induction of HNC. It has been suggested that such polymorphisms may be linked to cancer susceptibility. In this paper, we select four cytochrome P450 enzymes (CYP1A1, CYP1BA1, CYP2D6, and CYP2E1), and two N-acetyltransferase isozymes (NAT1 and NAT2) in order to summarize and analyze findings from the literature related to HNC risk by focusing on (i) the interaction between these genes and the environment, (ii) the impact of genetic defect on protein activity and/or expression, and (iii) the eventual involvement of race in such associations.

CYP63A2, a catalytically versatile fungal P450 monooxygenase capable of oxidizing higher-molecular-weight polycyclic aromatic hydrocarbons, alkylphenols, and alkanes

Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons, albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was found to possess a broad oxidizing capability toward structurally diverse hydrocarbons belonging to mutagenic/carcinogenic fused-ring higher-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), endocrine-disrupting long-chain alkylphenols (APs), and crude oil aliphatic hydrocarbon n-alkanes. A homology-based three-dimensional (3D) model revealed the presence of an extraordinarily large active-site cavity in CYP63A2 compared to the mammalian PAH-oxidizing (CYP3A4, CYP1A2, and CYP1B1) and bacterial aliphatic-hydrocarbon-oxidizing (CYP101D and CYP102A1) P450s. This structural feature in conjunction with ligand docking simulations suggested potential versatility of the enzyme. Experimental characterization using recombinantly expressed CYP63A2 revealed its ability to oxidize HMW-PAHs of various ring sizes, including 4 rings (pyrene and fluoranthene), 5 rings [benzo(a)pyrene], and 6 rings [benzo(ghi)perylene], with the highest enzymatic activity being toward the 5-ring PAH followed by the 4-ring and 6-ring PAHs, in that order. Recombinant CYP63A2 activity yielded monohydroxylated PAH metabolites. The enzyme was found to also act as an alkane ω-hydroxylase that oxidized n-alkanes with various chain lengths (C9 to C12 and C15 to C19), as well as alkyl side chains (C3 to C9) in alkylphenols (APs). CYP63A2 showed preferential oxidation of long-chain APs and alkanes. To our knowledge, this is the first P450 identified from any of the biological kingdoms that possesses such broad substrate specificity toward structurally diverse xenobiotics (PAHs, APs, and alkanes), making it a potent enzyme biocatalyst candidate to handle mixed pollution (e.g., crude oil spills).

Combustion derived ultrafine particles induce cytochrome P-450 expression in specific lung compartments in the developing neonatal and adult rat

Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAH) and can be a dominant contributor to ultrafine urban particulate matter (PM). Exposure to ultrafine PM is correlated with respiratory infections and asthmatic symptoms in young children. The lung undergoes substantial growth, alveolarization, and cellular maturation within the first years of life, which may be impacted by environmental pollutants such as PM. PAHs in PM can serve as ligands for the aryl hydrocarbon receptor (AhR) that induces expression of certain isozymes in the cytochrome P-450 superfamily, such as CYP1A1 and CYP1B1, localized in specific lung cell types. Although AhR activation and induction has been widely studied, its context within PM exposure and impact on the developing lung is poorly understood. In response, we have developed a replicable ultrafine premixed flame particle (PFP) generating system and used in vitro and in vivo models to define PM effects on AhR activation in the developing lung. We exposed 7-day neonatal and adult rats to a single 6-h PFP exposure and determined that PFPs cause significant parenchymal toxicity in neonates. PFPs contain weak AhR agonists that upregulate AhR-xenobiotic response element activity and expression and are capable inducers of CYP1A1 and CYP1B1 expression in both ages with different spatial and temporal patterns. Neonatal CYP1A1 expression was muted and delayed compared with adults, possibly because of differences in the enzyme maturation. We conclude that the inability of neonates to sufficiently adapt in response to PFP exposure may, in part, explain their susceptibility to PFP and urban ultrafine PM.

Polycyclic aromatic hydrocarbons in binary mixtures modulate the efficiency of benzo[a]pyrene to form DNA adducts in human cells

Exposure to polycyclic aromatic hydrocarbons (PAHs) always involves complex mixtures that may induce synergistic or antagonistic effects on the genotoxic properties and make risk assessment more difficult. In this study, we evaluated how particulate PAHs modulated the formation of DNA damage induced by carcinogenic benzo[a]pyrene (B[a]P). Single strand breaks and alkali labile sites, as well as BPDE-N²-dGuo DNA adducts were measured in the competent HepG2 cells by Comet assay and HPLC-tandem mass spectrometry, respectively. B[a]P, alone or in binary mixture with other PAHs (1 μM each), led to low amounts of strand breaks. In contrast, formation of BPDE-N²-dGuo adducts was significant and found to be enhanced in HepG2 co-treated for 14 h by B[a]P in the presence of either benzo[b]fluoranthene (B[b]F), dibenz[a,h]anthracene (DB[a,h]A) or indeno[1,2,3-cd]pyrene (IP). Opposite results were obtained with benzo[k]fluoranthene (B[k]F). The same observations were made when cells were pre-incubated with PAH before incubation with B[a]P. These results show that the interactions between PAHs are not direct competition reactions. Emphasis was then placed on the modulation of B[a]P-induced DNA damage by B[b]F and B[k]F. No difference in the time-course formation of DNA damage was observed. However, dose-response relationship differed between these two PAHs with a concentration-dependent inhibition of BPDE-N²-dGuo DNA by B[k]F whereas a constant level of potentiation for B[b]F was observed for concentrations higher than 1 μM. Altogether, these results show that the genotoxicity of B[a]P in binary mixtures with other carcinogenic PAH may be modulated. In such cases, a potentiation of BPDE-N²-dGuo adduct formation is most often observed with exception of B[k]F. Several biological mechanisms may account for these observations, including binding of PAHs to the Ah receptor (AhR), their affinity toward CYP450 and competition for metabolism. These different interactions have to be considered when addressing the intricate issue of the toxicity of mixtures.

Construction of a system that simultaneously evaluates CYP1A1 and CYP1A2 induction in a stable human-derived cell line using a dual reporter plasmid

Human CYP1A1 and CYP1A2 genes are in a head-to-head orientation on chromosome 15 and are separated by a 23-kb intergenic space. To our knowledge, this is the first report on a stable cell line that contains the 23-kb full-length regulatory region and is able to simultaneously assess the transcriptional activation of CYP1A1 and CYP1A2 genes. The stable cell line that constitutively expresses the reporter activities was constructed by inserting the dual reporter plasmid containing the 23-kb region between the CYP1A1 and CYP1A2 genes into the chromosome. Transcriptional activation of the CYP1A1 and CYP1A2 genes was measured simultaneously using luciferase (Luc) and secreted alkaline phosphatase (SEAP) activities, respectively. To demonstrate the utility of the stable cell line, CYP1A1/1A2 induction by the majority of compounds previously identified as CYP1A1/1A2 inducers was measured. The results clearly show that all compounds caused induction of reporter activities. In addition to assessing transcriptional activation of the CYP1A1 and CYP1A2 genes by measuring reporter activities, we determined the intrinsic CYP1A1 and CYP1A2 mRNA levels by treating them with the same compounds. The results suggest that this stable cell line may be used to rapidly and accurately predict CYP1A1/1A2 induction.

Effects of choline-deprivation on paracetamol- or phenobarbital-induced rat liver metabolic response

Choline is an essential nutrient that seems to be involved in a wide variety of metabolic reactions and functions in both humans and rodents. Various pathophysiological states have been linked to choline deprivation (CD). The aim of the present study was to determine the effect of CD upon biochemical, histological and metabolic alterations induced by drugs that affect hepatic functional integrity and various drug metabolizing systems via distinct mechanisms. For this purpose, paracetamol (ACET) or phenobarbital (PB) were administered to male Wistar rats that were fed with standard rodent chow (normally fed, NF) or underwent dietary CD. The administration of ACET increased the serum aspartate aminotransferase levels in NF rats, while CD restricted this increase. On the other hand, ACET suppressed alkaline phosphatase levels only in CD rats. Moreover, CD prevented the PB-induced increase of the mitotic activity of hepatocytes. The administration of ACET down-regulated CYP1A2 and CYP2B1 expression in CD rats, while up-regulating them in NF rats. The administration of PB suppressed CYP1A2 apoprotein levels in CD rats, whereas the drug had no effect on NF rats. The PB-induced up-regulation of CYP2B, CYP2E1 and CYP1A1 isozymes was markedly higher in CD than in NF rats. In addition, PB increased glutathione-S-transferase activity only in CD rats. Hepatic glutathione content (GSH) was suppressed by ACET in NF rats, whereas the drug increased GSH in CD rats. Our data suggest that CD has a significant impact on the hepatic metabolic functions, and in particular on those related to drug metabolism. Thus, CD may modify drug effectiveness and toxicity, as well as drug-drug interactions, particularly those related to ACET and PB.

Transcriptional responses of xenobiotic metabolizing enzymes, HSP70 and Na+/K+ -ATPase in the liver of rabbitfish (Siganus oramin) intracoelomically injected with amnesic shellfish poisoning toxin

Amnesic shellfish poisoning toxin domoic acid (DA) is a marine neurotoxin that accumulates in fish and shellfish, and has been implicated to be involved in human and marine wildlife mortality. The transcriptional responses of cytochrome P-450 1A (CYP1A), glutathione S-transferase alpha (GSTA), glutathione S-transferase rho (GSTR), heat shock protein 70 (HSP70), and Na(+)/K(+)-ATPase alpha 1 (ATP1A1) in the liver of rabbitfish (Siganus oramin) intracoelomically injected with DA, were investigated. Experimental fish were administered with one injection of DA (2 microg/g wet weight) or PBS as control. After 24 h, fish were killed and hepatic RNA was isolated. Partial cDNA of rabbitfish CYP1A, GSTA, GSTR, HSP70, ATP1A1, and beta-actin were obtained by PCR using degenerate primers. Using beta-actin as an external control, the relative liver CYP1A, GSTA, GSTR, HSP70, and ATP1A1 mRNA abundance of rabbitfish were determined by semi-quantitative RT-PCR within the exponential phase. The ratio CYP1A/beta-actin mRNA (%) of exposure group was determined to be 148.92+/-12.69, whereas the ratio of control group was 82.3+/-8.35, indicating that CYP1A was induced significantly in rabbitfish following DA exposure (P<0.05). Although the expressions of GSTA, HSP70, and ATP1A1 tended to increase and GSTR tended to decrease, no significant changes were found (P>0.05). The induction of hepatic CYP1A in response to DA suggests a potential role for fish phase I xenobiotic metabolizing enzyme in DA metabolism.

Predominant role of peripheral catecholamines in the stress-induced modulation of CYP1A2 inducibility by benzo(alpha)pyrene

The potential involvement of catecholamines and in particular of alpha(2)-adrenoceptor-related signalling pathways, in the regulation of drug-metabolizing enzymes by stress was investigated in Wistar rats after exposure to the environmental pollutant benzo(alpha)pyrene. For this purpose, total cytochrome P450 content, the CYP1A2 mRNA levels, 7-methoxyresorufin-O-dealkylase (MROD), 7-pentoxyresorufin-O-dealkylase (PROD) and p-nitrophenol hydroxylase activity levels were determined in the livers of rats exposed to repeated restraint stress after treatment with benzo(alpha)pyrene coupled with pharmacological manipulations of peripheral and/or central catecholamines and alpha(2)-adrenoceptors. The data show that stress is a significant factor in the regulation of CYP1A2 induction and that catecholamines play a central role in the stress-mediated modulation of hepatic CYP1A2 inducibility by benzo(alpha)pyrene. The up-regulating effect of stress on benzo(alpha)pyrene-induced CYP1A2 gene expression was eliminated after a generalized catecholamine depletion with reserpine. Similarly, in a state where only peripheral catecholamines were depleted and central catecholamines remained intact after guanethidine administration, the up-regulating effect of stress was eliminated. It is apparent that stress up-regulates the induction of CYP1A2 by benzo(alpha)pyrene mainly via peripheral catecholamines, while central catecholamines hold a minor role in the regulation. Pharmacological manipulations of alpha(2)-adrenoceptors appear to interfere with the effect of stress on the regulation of CYP1A2 inducibility. Either blockade or stimulation of alpha(2)-adrenoceptors with atipamezole and dexmedetomidine respectively, eliminated the up-regulating effect of stress on CYP1A2 benzo(alpha)pyrene-induced expression, while it enhanced MROD activity. In contrast, stress and pharmacological manipulations of catecholamines and alpha(2)-adrenoceptors did not affect total P450 content, the CYP2B1/2-dependent PROD and the CYP2E1-dependent p-nitrophenol hydroxylase activities. In conclusion, stress is a significant factor in the regulation of the CYP1A2 inducibility by benzo(alpha)pyrene, which in turn is involved in the metabolism of a large spectrum of toxicants, drugs and carcinogenic agents. Although the mechanism underlying the stress effect on CYP1A2 induction has not been clearly elucidated, it appears that peripheral catecholamines hold a predominant role, while central catecholamines and in particular, central noradrenergic pathways hold a minor role.

Induction of CYP1A1 and CYP1B1 by benzo(k)fluoranthene and benzo(a)pyrene in T-47D human breast cancer cells: roles of PAH interactions and PAH metabolites

The interactions of polycyclic aromatic hydrocarbons (PAH) and cytochromes P450 (CYP) are complex; PAHs are enzyme inducers, substrates, and inhibitors. In T-47D breast cancer cells, exposure to 0.1 to 1 microM benzo(k)fluoranthene (BKF) induced CYP1A1/1B1-catalyzed 17beta-estradiol (E(2)) metabolism, whereas BKF levels greater than 1 muM inhibited E(2) metabolism. Time course studies showed that induction of CYP1-catalyzed E(2) metabolism persisted after the disappearance of BKF or co-exposed benzo(a)pyrene, suggesting that BKF metabolites retaining Ah receptor agonist activity were responsible for prolonged CYP1 induction. BKF metabolites were shown, through the use of ethoxyresorufin O-deethylase and CYP1A1-promoter-luciferase reporter assays to induce CYP1A1/1B1 in T-47D cells. Metabolites formed by oxidation at the C-2/C-3 region of BKF had potencies for CYP1 induction exceeding those of BKF, whereas C-8/C-9 oxidative metabolites were somewhat less potent than BKF. The activities of expressed human CYP1A1 and 1B1 with BKF as substrate were investigated by use of HPLC with fluorescence detection, and by GC/MS. The results showed that both enzymes efficiently catalyzed the formation of 3-, 8-, and 9-OHBKF from BKF. These studies indicate that the inductive effects of PAH metabolites as potent CYP1 inducers are likely to be additional important factors in PAH-CYP interactions that affect metabolism and bioactivation of other PAHs, ultimately modulating PAH toxicity and carcinogenicity.

Cytochrome P450 1A isoenzymes in brain cells: Expression and inducibility in cultured rat brain neuronal and glial cells

Studies initiated to determine the expression of CYP1A1/1A2 isoenzymes in the primary cultures of rat brain neuronal and glial cells revealed significant activity of CYP1A-dependent 7-ethoxyresorufin-o-dealkylase (EROD) in microsomes prepared from both rat brain neuronal and glial cells. RT-PCR and immunocytochemical studies demonstrated constitutive mRNA and protein expression of CYP1A1 and 1A2 isoenzymes in cultured neuronal and glial cells. Cultured neurons exhibited relatively higher constitutive mRNA and protein expression of CYP1A1 and 1A2 isoenzymes, associated with higher activity of EROD than the glial cells. Induction studies with 3-methylchlorantherene (MC), a known CYP1A-inducer, resulted in significant concentration dependent increase in the activity of EROD in cultured rat brain cells with glial cells exhibiting a greater magnitude of induction than the neuronal cells. This difference in the increase in enzyme activity was also observed with RT-PCR and immunocytochemical studies, indicating relatively higher increase in CYP1A1 and 1A2 mRNA as well as protein expression in the cultured glial cells when compared to the neuronal cells. The greater magnitude of induction of CYP1A1 in glial cells is of significance, as these cells are components of the blood-brain barrier and it is suggested that they have a potential role in the toxication-detoxication mechanism. Our data indicating differences in the expression and sensitivity of CYP1A1 isoenzymes in cultured rat brain cells will not only help in identifying and distinguishing xenobiotic metabolizing capability of these cells but also in understanding the vulnerability of these specific cell types towards neurotoxicants.

Benzo(α)pyrene-induced up-regulation of CYP1A2 gene expression: Role of adrenoceptor-linked signaling pathways

CYP1A2, a principal catalyst for metabolism of various therapeutic drugs and carcinogens, among others, is in part regulated by the stress response. This study was designed to assess whether catecholamines and in particular adrenergic receptor-dependent pathways, modulate benzo(alpha)pyrene (B(alpha)P)-induced hepatic CYP1A2. To distinguish between the role of central and peripheral catecholamines in the regulation of CYP1A2 induction, the effect of central and peripheral catecholamine depletion using reserpine was compared to that of peripheral catecholamine depletion using guanethidine. The effects of peripheral adrenaline and L-DOPA administration were also assessed. The results suggest that alterations in central catecholamines modulate 7-methoxyresorufin O-demethylase activity (MROD), CYP1A2 mRNA and protein levels in the B(alpha)P-induced state. In particular, central catecholamine depletion, dexmedetomidine-induced inhibition of noradrenaline release and blockade of alpha(1)-adrenoceptors with prazosin, up-regulated CYP1A2 expression. Phenylephrine and dexmedetomidine-induced up-regulation may be mediated, in part, via peripheral alpha(1)- and alpha(2)-adrenoceptors, respectively. On the other hand, the L-DOPA-induced increase in central dopaminergic activity was not followed by any change in the up-regulation of CYP1A2 expression by B(alpha)P. Central noradrenergic systems appeared to counteract up-regulating factors, most likely via alpha(1)- and alpha(2)-adrenoceptors. In contrast, peripheral alpha- and beta-adrenoceptor-related signaling pathways are linked to up-regulating processes. The findings suggest that drugs that bind to adrenoceptors or affect central noradrenergic neurotransmission, as well as factors that challenge the adrenoceptor-linked signaling pathways may deregulate CYP1A2 induction. This, in turn, may result in drug-therapy and drug-toxicity complications.

Time-course changes of mixture effects on AhR binding-dependent luciferase activity in a crude extract from a compost sample

Crude extracts of environmental samples contain stable and labile aryl hydrocarbon receptor (AhR) ligands, and show huge activities in the cell-based bioassay, and these activities are higher than the chemically calculated induction equivalent values. It is thought that not only unidentified AhR ligands but also mixture effect among compounds might contribute to these activities. In the previous work, we have indicated that hydrophobic compounds in household sewage sludge (HSS) compost may interact synergistically with 2,3,7,8-TCDD in the CALUX (DR-CALUX: Dioxin-Responsive Chemical-Activated Luciferase gene eXpression) assay [Suzuki, G., Takigami, H., Kushi, Y., Sakai, S., 2004. Evaluation of mixture effects in a crude extract of compost using the CALUX bioassay and HPLC fractionation. Environ. Int. 30, 1055-1066]. In this study, we focused on co-existing stable compounds such as halogenated aromatic hydrocarbons (HAHs) and labile compounds such as polyaromatic hydrocarbons (PAHs) in the crude extract and investigated the time-course changes of mixture effects among compounds in environmental samples using the CALUX assay and normal-phase high-performance liquid chromatography (NP-HPLC) fractionation. We confirmed that CYP1A-inducing PAHs and HAHs could be separated by NP-HPLC on a nitrophenylpropylsilica (NITRO) column. To determine whether the activities of AhR ligands in environmental samples (including the HSS compost) could be assessed by the additivity theory, we compared the CALUX activity of the crude extract with the arithmetical sum of the activities of all the fractions separated by NP-HPLC. We confirmed a potentiation of CALUX activity at 12-, 24- and 48-h exposure durations. In contrast, CALUX activity increased additively at 6- and 72-h exposure durations. CALUX activity was potentiated when the CALUX activity of the HPLC fractions showed a remarkable reduction resulting in a change of activity profiles. In contrast, additivity was observed at a 72-h exposure duration when the CALUX activity of the HPLC fractions showed neither remarkable reduction nor a change in profile. Our results suggest that differences in the metabolic decomposition of compounds affected mixture effects on CALUX activity in a crude extract from HSS compost.

Suppressive effect of 1-nitropyrene on benzo[a]pyrene-induced CYP1A1 protein expression in HepG2 cells

The genotoxicity of polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs may be influenced by the interaction of the compounds. In this study, our data showed that benzo[a]pyrene (BaP)-DNA adduct levels were decreased in a dose-dependent manner when the human hepatoma cell line HepG2 simultaneously treated with BaP and 1-nitropyrene (1-NP). To further investigate the molecular mechanism by which 1-NP interferes with the covalent binding of BaP to DNA, we conducted experiments to analyze the mRNA level and protein stability of cytochrome P450 1A1 (CYP1A1), which is engaged in the activation of BaP, leading to the generation of BaP-DNA adducts. Northern blot analysis presented that 1-NP attenuated BaP-induced CYP1A1 mRNA expression by 30.4-39.6% (p < 0.05). Western blot analysis revealed that the co-treatment with BaP and 1-NP resulted in a significant inhibition of BaP-induced CYP1A1 protein expression (70.7-88.2%, p < 0.05). However, the decrease in CYP1A1 protein levels was significantly larger than that in CYP1A1 mRNA levels. To confirm the effect of 1-NP on the CYP1A1 protein expression, in vitro proteolysis of CYP1A1 protein was evaluated. The results demonstrated that the addition of 1-NP enhanced CYP1A1 protein degradation and the proteolysis of CYP1A1 protein was inhibited by the addition of an antioxidant, dithiothreitol. In addition, the relative levels of reactive oxygen species (ROS) were elevated in HepG2 cells co-treated with BaP and 1-NP, indicating that the decrease of CYP1A1 protein level was probably attributed to the production of ROS generated by binary mixture. Taken together, these findings suggested that the transcriptional suppression and posttranslational mechanism may be involved in loss of CYP1A1 protein, causing the decrease of BaP-DNA adduct levels in the presence of binary mixtures of 1-NP and BaP.

Organochlorine insecticides: impacts on human HepG2 cytochrome P4501A, 2B activities and glutathione levels

This study examined the effects of the organochlorine (OC) insecticides chlordane, o,p'-DDT, dieldrin, endosulfan, kepone, methoxychlor, and toxaphene on human HepG2 cytochrome P450 (1A-EROD and 2B-PROD) activities and glutathione (GSH) levels. Cells were exposed for 24 h at high concentrations (1, 5 or 10 mM) and for 48 h at lower concentrations ranging from 0.01 to 1 mM to evaluate dose responses. Our results show that after 48 h all but dieldrin significantly induced both P4501A and 2B. P4502B responses were greater at all exposure concentrations and times. Mixed responses in GSH levels were observed. All OCs except dieldrin and MXC significantly depleted GSH after 24 h. At 48 h, chlordane, endosulfan and toxaphene significantly increased GSH at low levels and decreased GSH at high levels, while kepone and methoxychlor produced significant declines in GSH at all concentrations. These results support findings of OC insecticides inducing CYP1A, 2B in rats, with CYP2B responses more important. GSH levels declined when P4502B activity was significantly elevated and were significantly increased in the absence of significant P450 activity, suggesting that GSH levels influence the catalytic activity of the cytochrome P450s and the cytochrome P450s influence the cell's ability to regulate GSH.

Role of adrenoceptor-linked signaling pathways in the regulation of CYP1A1 gene expression

Alpha2-adrenoceptor agents as well as stress affect the activity of several hepatic monoxygenases including those related to CYP1A enzymes. This study was therefore designed to assess the role of central and/or peripheral catecholamines and, in particular, of adrenoceptors in the regulation of B(alpha)P-induced cytochrome CYP1A1 expression. In order to discriminate the role of central from that of peripheral catecholamines in the regulation of CYP1A1 induction, the effect of central and peripheral catecholamine depletion using reserpine versus only peripheral catecholamine depletion using guanethidine was assessed. By using selected agonists and antagonists, the role of alpha and beta-adrenoceptors in the regulation of CYP1A1 induction was evaluated. The results showed that the central catecholaminergic system has a negative regulatory effect on 7-ethoxyresorufin O-deethylase (EROD) inducibility by benzo(alpha)pyrene (B(alpha)P), and that this may be mediated via alpha1-, alpha2- and beta-adrenoceptors. Specifically, stimulation of alpha2-adrenoceptors with dexmedetomidine and blockade of alpha1- or beta-adrenoceptors with prazosin or propranolol respectively, resulted in a further increase of EROD inducibility. Adrenoceptors were found to be involved in the regulation of the CYP1A1 gene at mRNA level. Both, reduced noradrenaline release in central nervous system induced with dexmedetomidine and central catecholamine depletion, as well as blockade of central alpha1-adrenoceptors induced with prazosin, all were associated with up-regulation of CYP1A1 expression. In contrast, stimulation of central beta-adrenoceptors with isoprenaline resulted in a down-regulation of CYP1A1 expression. Our observations indicate that drugs, which stimulate or block adrenoceptors and catecholamine release may lead to complications in drug therapy and modulate the toxicity or carcinogenicity of drugs that are substrates for the CYP1A1.

Evaluation of mixture effects in a crude extract of compost using the CALUX bioassay and HPLC fractionation

Potential synergistic interactions between polycyclic aromatic hydrocarbons in a household sewage sludge compost extract were investigated using the Dioxin-Responsive Chemical-Activated Luciferase gene eXpression (DR-CALUX) assay and reverse-phase high-performance liquid chromatography (RP-HPLC) fractionation. The biological activity of the crude extract was measured in vitro using the CALUX assay. The CALUX activity of the extract was as potent as 360-pg CALUX-TEQ (2,3,7,8-TCDD equivalent value) per g sample, this was 70 times above the WHO-TEQ value which was derived from chemical analyses of dioxins/furans and dioxin-like PCBs of the mixture. The CALUX activity pattern of the crude extract and the retention times of 26 polycyclic aromatic compounds (PACs), as determined by RP-HPLC on an octadecylsilica column, suggested that the dioxin-like compounds with the log K(OW) (n-octanol/water partition coefficient) values corresponding to 6.0-7.0 contributed highly to the whole activity. The CALUX activity of the crude extract was three times the sum of the CALUX activities of the RP-HPLC separated fractions. Mixture effects were assessed by co-exposure of each HPLC fraction and 2,3,7,8-TCDD to the cells. The four concentration levels of added 2,3,7,8-TCDD corresponded to the TEQ value in the original compost sample. The experimental CALUX activity was higher than the predicted CALUX activity for some fractions. It was demonstrated that some compounds in the compost sample interacted synergistically with 2,3,7,8-TCDD in terms of dioxin-like activity. This finding points out the necessity for detailed investigation of synergistic effects in environmental samples.

Stress-mediated modulation of B(α)P-induced hepatic CYP1A1: role of catecholamines

The present study investigated the involvement of catecholamines in stress-mediated alterations in CYP1A1 induction by benzo(alpha)pyrene (B(alpha)P) in Wistar rats. This was achieved by measuring EROD activity and CYP1A1 mRNA levels in liver tissue from rats exposed to restraint stress and B(alpha)P coupled with pharmacological modulation of peripheral and central catecholamine levels and different adrenoceptors. In a state of reserpine-induced central and peripheral catecholamine depletion, stress strongly suppressed EROD induction. Peripheral catecholamines do not appear to play a critical role in the stress-mediated modulation of EROD inducibility by B(alpha)P. Stress did not alter EROD inducibility by B(alpha)P when peripheral catecholamines were either depleted by guanethidine or supplemented by peripheral adrenaline administration. On the other hand, central noradrenergic systems appear to have a role in the stress-mediated changes in B(alpha)P-induced EROD activity and Cyp1A1 gene expression. Stimulation or blockade of noradrenaline release with atipamezole and dexmedetomidine, respectively, significantly modified the up-regulating effect of stress. Alpha1 adrenoceptors also appear to participate in the effect of stress on EROD inducibility. Alpha1-blockade with prazosin potentiated the up-regulating effect of stress, possibly preventing the down-regulating effect of noradrenaline. Beta adrenoceptors also seem to be involved directly or indirectly in the stress-mediated modulation of Cyp1A1, as propranolol (beta-antagonist) blocked the down-regulating effect of stress on B(alpha)P-induced Cyp1A1 gene expression. Plasma corticosterone alterations after stress were not related to alterations in the B(alpha)P-induced EROD activity and Cyp1A1 gene expression. In conclusion, stress appears to interfere in the regulation of B(alpha)P-induced hepatic CYP1A1 in an unpredictable manner and via signalling pathways not always directly related to catecholamines. In particular, whenever drug treatment disrupts noradrenergic neurotransmission, other stress-stimulated factors appear to modify the induction of CYP1A1. In summary, regulation of induction of hepatic CYP1A1 during stress appears to involve various components of the stress system, including central and peripheral catecholamines, which interact in a complex manner, yet to be elucidated.

Environmental exposure and lung cancer among nonsmokers: an example of Taiwanese female lung cancer

Lung cancer is the leading cause of cancer death worldwide and in Taiwan. Cigarette smoking is considered to be the most important risk factor, since about 90% of lung cancer can be related to cigarette smoking. Despite the recent decrease of cigarette smoking, lung cancer is still the leading cause of cancer death in the United States. In Taiwan, only around 50% of lung cancer incidence could be associated with cigarette smoking, particularly less than 10% of Taiwanese women are smokers. Thus, the aetiology of lung cancer for nonsmokers remains unknown. DNA damages including bulky and oxidative damage may be related with mutation of tumor suppressor genes, such as p53 gene. The high DNA adduct levels in female may be associated with frequent exposure to indoor cooking oil fumes (COF) and outdoor heavy air pollution. Oxidative stress induced by COF was also discussed. Different p53 mutation spectra and mutation frequency between genders reflected that different environmental factors may be involved in nonsmoking male and female lung cancer development. Most importantly, our recent report has demonstrated that human papillomavirus (HPV) infection was associated with nonsmoking female lung cancer. Based on our studies with Taiwanese nonsmoking lung cancer as the model, the possible aetiological factors of lung cancer incidence in Taiwanese nonsmokers were elucidated.

Summary of information on human CYP enzymes: human P450 metabolism data

This chapter is an update of the data on substrates, reactions, inducers, and inhibitors of human CYP enzymes published previously by Rendic and DiCarlo (1), now covering selection of the literature through 2001 in the reference section. The data are presented in a tabular form (Table 1) to provide a framework for predicting and interpreting the new P450 metabolic data. The data are formatted in an Excel format as most suitable for off-line searching and management of the Web-database. The data are presented as stated by the author(s) and in the case when several references are cited the data are presented according to the latest published information. The searchable database is available either as an Excel file (for information contact the author), or as a Web-searchable database (Human P450 Metabolism Database, www.gentest.com) enabling the readers easy and quick approach to the latest updates on human CYP metabolic reactions.

Human 8-oxoguanine DNA glycosylase 1 mRNA expression as an oxidative stress exposure biomarker of cooking oil fumes

Epidemiological studies have indicated that the exposure to carcinogenic components formed during the cooking of food might be associated with lung cancer risk of Chinese women. Previous studies have confirmed that cooking oil fumes from frying fish (COF) contained relatively high amount of benzo[a]pyrene, 2-methyl-3,8-dimethylimidazo[4,5-f] qunoxaline, benzene, and 1,3-butadiene, reported in fumes from heated soybean oil. Thus, we consider that oxidative stress induced by COF may play a role in lung cancer development among Chinese women. To verify whether the oxidative DNA damage was induced by COF, high-performance liquid chromatography (HPLC) analysis data showed that the levels of 8-hydroxydeoxyguanine (8-OH dG) were increased in a dose-dependent manner when calf thymus DNA reacted with various concentrations of COF. Since human 8-oxoguanine DNA glycosylase 1 (hOGG1) was a repair enzyme for removing 8- OH dG from damaged DNA, we hypothesized that hOGG1 mRNA may be used to assess the risk of oxidative damage induced by the exposure of COF. The results from reverse-transcription polymerase chain reaction showed that the hOGG1 mRNA expression was induced by hydrogen peroxide (H2O2) and COF in human lung adenocarcinoma CL-3 cells. To elucidate whether hOGG1 mRNA expression was an exposure biomarker of COF, a cross-sectional study of 238 subjects including 94 professional cooks, 43 housewives, and 101 COF-nonexposed control subjects was conducted. The hOGG1 mRNA expression frequencies of COF-exposed cooks (27 of 94, 28.7%) and housewives (6 of 43, 14%) were significantly higher than those of control subjects (4 of 101, 4%). After adjusting for age, sex, and smoking and drinking status, the odds risks (ORs) of housewives versus control and cooks versus control were 3.94 (95% confidence interval [CI] = 0.95-16.62) and 10.12 (95% CI = 2.83-36.15), respectively. These results indicated that hOGG1 may be adequate to act as an exposure biomarker to assess the oxidative DNA damage induced by COF. This also suggests that oxidative stress induced by COF may play a role in lung cancer development among Chinese women.