Levels Of Aromatic DNA Adducts Research Articles

Aromatic DNA adducts and breast cancer risk: a case-cohort study within the EPIC-Spain.

Epidemiologic evidence linking environmental exposure to polycyclic aromatic hydrocarbons (PAH) with breast cancer is limited. Measurement of DNA adducts formed by aromatic compounds, including PAH, has been carried in breast tissue samples and white blood cells from women with breast cancer and different kinds of controls. However, these studies provide inconsistent results and bias cannot be ruled out. During the 7-year follow-up period, 305 women were diagnosed with first primary breast cancer in the EPIC-Spain cohort, and were compared with a sample of 149 women without breast cancer at recruitment, using a case-cohort approach. Aromatic adducts to DNA from leukocytes collected at recruitment were measured by means of the 32P-post-labelling technique. The relative risk and 95% confidence interval (CI), adjusted by relevant confounders, were estimated by a modified version of Cox proportional hazards model. There was a significant increased risk for developing breast cancer when DNA adduct concentrations were doubled, with adjusted RR of 1.61 (95% CI 1.29-2.01). The increase in breast cancer risk was observed both for pre- and post-menopausal women. There was a significant interaction with tobacco smoking and body mass index, with higher effect of DNA adducts on breast cancer risk among smokers and women with normal weight. The results from our study support the hypothesis that factors leading to higher levels of aromatic DNA adducts in white blood cells may be involved in development of breast cancer.

Abstract A10: Exposure to heterocyclic aromatic amines, genetic susceptibility and bulky DNA adduct levels in blood leukocytes

Abstract Background: There is compelling evidence to suggest that aspects of diet influence cancer risk; specifically, high meat consumption is associated with elevated risks. Exposure to heterocyclic aromatic amines (HAAs), carcinogens produced in meat when cooked at high temperatures, is a hypothesized explanation for the meat-cancer relationship. Reactive HAA metabolites form adducts with DNA; left unrepaired, adducts can induce mutations which may initiate/promote carcinogenesis. Genetic differences in the ability to biotransform HAAs (as conferred by polymorphisms in CYP1A1, CYP1A2, CYP1B1, NAT1 and NAT2) and repair DNA adducts (as conferred by polymorphisms in XPA, XPD and XRCC1) is postulated to modify the dietary HAAs-DNA adduct relationship. Methods: In a cross-sectional study of 99 healthy volunteers recruited from Kingston, Ontario, Canada, dietary exposure to HAAs and bulky DNA adduct levels in blood leukocytes was investigated. A detailed questionnaire was used in combination with a mutagen database to estimate average intake of dietary HAAs. Specifically, the detailed questionnaire obtained the average frequency of consumption, usual level of doneness and usual serving size of nine commonly consumed meats items with high HAA content. Bulky DNA adduct levels were measured in blood collected after an overnight fast using 32P-postlabelling. Least squares regression was used to examine the relationship between dietary HAA exposure and bulky DNA adduct levels in blood. Gene-diet interactions between dietary HAAs and genetic factors relevant to the biotransformation of HAAs and DNA repair were also examined. Results: No main effects of dietary exposure to HAAs on bulky DNA adduct levels were observed. However, polymorphisms in NAT1 were found to associate with bulky DNA adduct levels. Specifically, those with the putative NAT1*10 rapid acetylator phenotype had a lower adduct level than those with the slow acetylator phenotype (p=0.02). Furthermore, having five or more ‘at-risk’ genotypes was associated with higher bulky DNA adduct levels (p=0.03). Gene-diet interactions were also observed between the NAT1*10 allele and dietary HAAs (p<0.05); specifically, among the slow acetylator phenotype, higher intakes of dietary HAAs were associated with an increase in DNA adduct levels compared to lower intakes. Conclusions: This study provides evidence of a biologic relationship between dietary HAAs, genetic susceptibility and bulky DNA adduct formation. The lack of a strong independent association between dietary HAAs and DNA adducts suggests that dietary HAAs are not a large contributor to bulky DNA adducts in this Canadian population; future studies should consider relevant gene-diet interactions to clarify the potential role of HAAs in carcinogenesis. Citation Format: Vikki Ho, Sarah Peacock, Thomas E. Massey, Roger W. L. Godschalk, Frederik-Jan van Schooten, Jian Chen, Will D. King. Exposure to heterocyclic aromatic amines, genetic susceptibility and bulky DNA adduct levels in blood leukocytes. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A10.

Aromatic adducts and lung cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) Spanish cohort

In this case-cohort study, we examined the association between bulky DNA adducts and the risk of lung cancer within the European Prospective Investigation into Cancer and Nutrition (EPIC) Spanish cohort with an average 7-year follow-up, including 98 cases of primary lung cancer and 296 subjects randomly selected from the cohort. Aromatic adducts were measured using (32)P-postlabeling in leukocyte DNA from blood samples collected at enrollment. The association between DNA adducts and the risk of lung cancer was estimated using a Cox proportional hazards model with a modified partial likelihood. There was an overall significant increased risk for developing lung cancer when DNA adduct concentrations were doubled, with relative risk (RR) adjusting for all relevant confounders of 1.36 with 95% confidence interval (CI) 1.18-157. There was a significant increased risk for developing lung cancer when DNA adduct concentrations were doubled for current smokers and among subjects exposed to PAH at work; there was also a slightly higher increase among males than females. However, no statistically significant differences were observed for the effect of adduct levels across smoking status, sex or occupational exposure to PAH. A meta-analysis combined four prospective studies, including this study, resulting in a significant association among current smokers, with an overall estimate of 34% increase in the risk of lung cancer when doubling the level of aromatic DNA adducts in leukocytes.

Influence of genetic polymorphisms on biomarkers of exposure and effects in children living in Upper Silesia

This article is a follow-up to our previous molecular epidemiology studies on the DNA damage in children from the Upper Silesia region of Poland. It is expected that metabolic and DNA repair gene polymorphisms may modulate individual susceptibility to environmental exposure. In this study, we investigate the association between polymorphisms of metabolising (CYP2D, EPHX1, GSTM1, GSTP1, GSTT1, NAT2) and DNA repair (XPD, XRCC1, XRCC3) genes and selected biomarkers of exposure and effect such as levels of 1-hydroxypyrene (1-OHP) and urinary mutagenicity, aromatic DNA adducts, sister chromatid exchange (SCE) and micronuclei (MN) in 74 children. Both 1-OHP concentration and urinary mutagenicity tested by TA98+S9 were significantly higher in individuals with EPHX1 (exon 4) Arg/Arg genotype than in individuals with other genotype. The EPHX1 (exon 3) significantly affected urinary mutagenicity tested with strain YG1024+S9. The urinary mutagenicity in individuals with Tyr/Tyr homozygotes was lower than in individuals with Tyr/His and His/His (1057±685 vs. 1432±1003 revertants/mol creatinine). XRCC3 Met/Met genotype was associated with significantly higher levels of 1-OHP in urine compared with only The/Met genotype. The PAH-DNA adduct levels in the subgroup with GSTM1 null genotype was 2-fold higher than in individuals with GSTM1 active (7.06±5.12 vs. 13.14±9.81 adduct/10(8) nucleotides). The mean level of aromatic DNA adducts in children with deletion of the GSTT1 gene was significantly higher compared with individuals with that gene present (8.03±6.23 vs. 14.66±10.70 adduct/10(8) nucleotides). Also the carriers of the XPD Lys/Lys genotype showed higher levels of DNA adducts than heterozygotes (13.16±9.70 vs. 6.81±5.86 adducts/10(8) nucleotides). Children carrying the XRCC3-241 Met/Met genotype exhibited a higher number of SCE in peripheral blood lymphocytes than carriers of Thr/Met allele (8.15±0.86 vs. 7.62±0.79 SCE/cell). It was also observed that children with the GSTP1 slow conjugator had significantly elevated MN in peripheral blood lymphocytes compared with fast conjugator (4.23±3.49 vs. 6.56±5.00 MN/1000 cells).

Variation in PAH-related DNA adduct levels among non-smokers: the role of multiple genetic polymorphisms and nucleotide excision repair phenotype.

Polycyclic aromatic hydrocarbons (PAHs) likely play a role in many cancers even in never-smokers. We tried to find a model to explain the relationship between variation in PAH-related DNA adduct levels among people with similar exposures, multiple genetic polymorphisms in genes related to metabolic and repair pathways, and nucleotide excision repair (NER) capacity. In 111 randomly selected female never-smokers from the Golestan Cohort Study in Iran, we evaluated 21 SNPs in 14 genes related to xenobiotic metabolism and 12 SNPs in eight DNA repair genes. NER capacity was evaluated by a modified comet assay, and aromatic DNA adduct levels were measured in blood by32P-postlabeling. Multivariable regression models were compared by Akaike's information criterion (AIC). Aromatic DNA adduct levels ranged between 1.7 and 18.6 per 10(8) nucleotides (mean: 5.8 ± 3.1). DNA adduct level was significantly lower in homozygotes for NAT2 slow alleles and ERCC5 non-risk-allele genotype, and was higher in the MPO homozygote risk-allele genotype. The sum of risk alleles in these genes significantly correlated with the log-adduct level (r = 0.4, p < 0.001). Compared with the environmental model, adding Phase I SNPs and NER capacity provided the best fit, and could explain 17% more of the variation in adduct levels. NER capacity was affected by polymorphisms in the MTHFR and ERCC1 genes. Female non-smokers in this population had PAH-related DNA adduct levels three to four times higher than smokers and occupationally-exposed groups in previous studies, with large inter-individual variation which could best be explained by a combination of Phase I genes and NER capacity.

Sex differences in lung cancer susceptibility: A review

Several epidemiologic and molecular epidemiologic studies have indicated that, for a given number of cigarettes smoked, women may be at higher risk of lung cancer compared with men. The objective of this article was to address sex differences in lung cancer susceptibility, with special emphasis on genetic, biological, and sex-related hormonal factors. Using the search terms gender or sex difference in combination with lung cancer, susceptibility, survival, polymorphism, biomarker, and smoking, we conducted a review of the available literature in the MEDLINE, Current Contents, and Web of Science biomedical databases. Relevant English-language publications (January 1966-December 2009) on sex differences in lung cancer were identified. Higher levels of polycyclic aromatic hydrocarbon DNA adducts were observed in female lung cancer patients compared with their male counterparts, even though the level of tobacco carcinogens was lower among women than among men. DNA repair capacity was found to be lower in female lung cancer patients than in their male counterparts. A higher frequency of G-to-T transversion mutations in the tumor suppressor protein p53 gene has been observed in women compared with men. Non-small cell lung tumors in women appeared to be more likely than those in men to harbor K-ras, c-erbB-2, or epidermal growth factor receptor mutations. Sex differences have been identified in the expression of the cytochrome P4501A1 gene and gastrin-releasing peptide receptor gene, with women exhibiting higher gene expression than men for both of these genes. Evidence supporting a possible association between estrogen and lung cancer risk based on epidemiologic studies has not been consistent, but sex hormones may influence susceptibility to lung carcinogenesis. Women may be more susceptible to tobacco smoke and potentially more vulnerable to lung cancer development. If additional studies yield supporting evidence, researchers, the public, and policy makers should focus on ways to reduce the risk of lung cancer for women.

Relationship between N-acetyltransferase 2 single-nucleotide polymorphisms and phenotype

Relationship between N-acetyltransferase 2 single-nucleotide polymorphisms and phenotype

Morinda Citrifolia (Noni) Reduces Cancer Risk in Current Smokers by Decreasing Aromatic DNA Adducts

Quantitative determination of aromatic DNA adducts in peripheral blood lymphocytes (PBLs) of current smokers is an useful surrogate biomarker for the evaluation of environmental carcinogen exposure or chemopreventive intervention. In this study, we examined the impact of Tahitian Noni Juice (TNJ) on the aromatic DNA adducts of PBLs, before and after a 1-mo intervention, using 32P postlabeling assay. Of 283 enrolled, 203 smokers completed the trial. Aromatic DNA adducts levels in all participants were significantly reduced by 44.9% (P < 0.001) after drinking 1 to 4 oz of TNJ for 1 mo. Dose-dependent analyses of aromatic DNA adduct levels showed reductions of 49.7% (P < 0.001) in the 1-oz TNJ group and 37.6% (P < 0.001) in the 4-oz TNJ group. Gender-specific analyses resulted in no significant differences in the 4-oz TNJ groups. Interestingly, the 1-oz TNJ group showed a reduction of 43.1% (P < 0.001) in females compared with 56.1% (P < 0.001) in males. The results suggest that drinking 1 to 4 oz of TNJ daily may reduce the cancer risk in heavy cigarette smokers by blocking carcinogen-DNA binding or excising DNA adducts from genomic DNA.

PAH–DNA adducts in environmentally exposed population in relation to metabolic and DNA repair gene polymorphisms

Epidemiologic studies indicate that prolonged exposure to particulate air pollution may be associated with increased risk of cardiovascular diseases and cancer in general population. These effects may be attributable to polycyclic aromatic hydrocarbons (PAHs) adsorbed to respirable air particles. It is expected that metabolic and DNA repair gene polymorphisms may modulate individual susceptibility to PAH exposure. This study investigates relationships between exposure to PAHs, polymorphisms of these genes and DNA adducts in group of occupationally exposed policemen (EXP, N = 53, males, aged 22–50 years) working outdoors in the downtown area of Prague and in matched “unexposed” controls (CON, N = 52). Personal exposure to eight carcinogenic PAHs (c-PAHs) was evaluated by personal samplers during working shift prior to collection of biological samples. Bulky-aromatic DNA adducts were analyzed in lymphocytes by 32P-postlabeling assay. Polymorphisms of metabolizing (GSTM1, GSTP1, GSTT1, EPHX1, CYP1A1-MspI) and DNA repair (XRCC1, XPD) genes were determined by PCR-based RFLP assays. As potential modifiers and/or cofounders, urinary cotinine levels were analyzed by radioimmunoassay, plasma levels of vitamins A, C, E and folates by HPLC, cholesterol and triglycerides using commercial kits. During the sampling period ambient particulate air pollution was as follows: PM10 32–55 μg/m 3, PM2.5 27–38 μg/m 3, c-PAHs 18–22 ng/m 3; personal exposure to c-PAHs: 9.7 ng/m 3 versus 5.8 ng/m 3 ( P < 0.01) for EXP and CON groups, respectively. The total DNA adduct levels did not significantly differ between EXP and CON groups (0.92 ± 0.28 adducts/10 8 nucleotides versus 0.82 ± 0.23 adducts/10 8 nucleotides, P = 0.065), whereas the level of the B[ a]P-“like” adduct was significantly higher in exposed group (0.122 ± 0.036 adducts/10 8 nucleotides versus 0.099 ± 0.035 adducts/10 8 nucleotides, P = 0.003). A significant difference in both the total ( P < 0.05) and the B[ a]P-“like” DNA adducts ( P < 0.01) between smokers and nonsmokers within both groups was observed. A significant positive association between DNA adduct and cotinine levels ( r = 0.368, P < 0.001) and negative association between DNA adduct and vitamin C levels ( r = −0.290, P = 0.004) was found. The results of multivariate regression analysis showed smoking, vitamin C, polymorphisms of XPD repair gene in exon 23 and GSTM1 gene as significant predictors for total DNA adduct levels. Exposure to ambient air pollution, smoking, and polymorphisms of XPD repair gene in exon 6 were significant predictors for B[ a]P-“like” DNA adduct. To sum up, this study suggests that polymorphisms of DNA repair genes involved in nucleotide excision repair may modify aromatic DNA adduct levels and may be useful biomarkers to identify individuals susceptible to DNA damage resulting from c-PAHs exposure.

Stężenie wybranych biomarkerów toksyczności dymu tytoniowego u osób palących tytoń chorych na raka krtani

An incidence of laryngeal cancer is strongly connected with exposure to tobacco smoke containing dozens of carcinogens. Genotoxic agents such as polycyclic aromatic hydrocarbons present in tobacco smoke are responsible for lesions of structure DNA and formation of DNA adducts by metabolically activated intermediates. Detecting the presence of DNA adducts in human tissues is therefore, a tool for studies of cancer. An evidence demonstrates that DNA adducts are useful markers of carcinogen exposure. The aim of this work was estimation of relationship between cigarette smoke exposure, determined as urinary cotinine and urinary 1-hydroxypyrene concentration, and number of aromatic-DNA adducts in blood lymphocytes. The study group consisted of 60 men at the age of 45 up to 65 years - 20 healthy non-smokers, 20 healthy current smokers and 20 current smokers with primary larynx cancer, which was classified histopathologically as squamous cell carcinoma. The cotinine and 1-hydroxypyrene were determined in the urine with high performance liquid chromatography. Analysis of DNA adducts was performed by the 32P - postlabelling method. Urinary cotinine concentration in healthy smokers and cancer subjects in comparison with non-smokers was significant higher than in non-smokers, respectively, 29- and 31-fold higher but differences between healthy and sicks smokers were insignificant. Concentration of 1-hydroxypyrene in urine of healthy and cancer subjects was significantly higher (9- and 10-fold higher, respectively) compared with non-smokers. The highest level of aromatic-DNA adducts was found in lympfocytes of healthy smokers but differences between number of adducts in healthy smokers compared with non-smokers (+35%) and cancer subjects (+7,1%) were insignificant. The Pearson's coefficient (r) for the correlation between aromatic-DNA level and urinary cotinine or 1-hydroxypyrene concentration were significant only in cancer subjects group (r = 0,676, p = 0,011 and r = 0,465, p = 0,039, respectivelly). The results suggest that cotinine and 1-hydroxypyrene concentration in urine are useful biomarkers of the tobacco smoke exposure. In contrast the levels of aromatic-DNA adducts in lymphocytes are not suitable for that purpose. It seems that none of investigated compounds are the risk predictor of larynx cancer.

Polyphenol associated-DNA adducts in lung and blood mononuclear cells from lung cancer patients

The formation of smoking induced-DNA adducts is a critical factor in the induction of human lung cancer. As derivates of benzene and polyaromatic hydrocarbons (PAHs) are important compounds of tobacco smoke, in DNA isolated from human lung and blood mononuclear cells (MNCs) from 38 lung cancer patients, we used the 32P-postlabeling assay to detect polyphenol associated DNA adducts. Two DNA adducts were detected in blood MNCs and lung tissue that co-chromatographed with DNA modifications from HL60 cells treated with combinations of benzene metabolites (e.g., hydroquinone and benzenetriol). These adducts were designated polyphenol-associated DNA adducts. Relative adduct levels for polyphenolic adducts were five-fold higher than aromatic adducts in both lung and MNCs. A significant correlation was observed between levels of polyphenol adducts and total duration of cigarette smoking in lung ( r=0.34; P<0.04) and MNCs ( r=0.7; P<0.04), but no correlation between levels of polyphenol adducts and pack-years consumption of cigarettes nor time since quitting smoking in former smokers. Long term former smokers and the one non-smoker in the study had detectable levels of polyphenol adducts. Surprisingly, the levels of polyphenol adducts in MNCs were highly correlated with aromatic adduct levels ( r=0.84; P<0.001). Individual aromatic adducts in MNCs also correlated with polyphenol adducts. Total polyphenol adduct levels had a correlation with aromatic DNA adduct levels in lung tissue ( r=0.46; P<0.01). To our knowledge these results are the only comparison of adducts in MNCs with lung tissue, and the only data set indicating that blood MNCs are a valid surrogate for lung adduct DNA burden.

Evaluation of DNA damage in mice topically exposed to total particulate matter from mainstream and sidestream smoke from cigarettes and bidis.

The genotoxic potential of total particulate matter (TPM) from mainstream smoke (MS) and sidestream smoke (SS) of Indian smoking products, namely cigarettes and bidis, as well as a brand of US cigarettes, was studied by determining the levels of bulky aromatic DNA adducts in mouse tissues. TPM from MS or SS of various smoking products [equal weights (2.5 mg) or the amount derived from equal (0.25) cigarette/bidi] was applied topically to mouse skin once a day for four consecutive days and adduct levels were determined in DNA from skin and lung by (32)P-post-labelling analysis. Relatively higher levels of bulky aromatic DNA adducts were noted in mouse skin treated with MS from a single Indian non-filter (INF) cigarette when compared with MS of a single bidi (with about half the product weight and one-quarter the tobacco compared with a cigarette), while comparable adduct levels were noted with SS from these two products. Considering the differences in the yields of constituents of tobacco smoke from the different products analyzed, the genotoxic potential of INF, Indian filter king (IFK) and American filter (AF) cigarettes as well as bidis was determined by topically applying an equal amount of TPM (rather than equal product-derived TPM). SS-derived TPM from all the products showed relatively higher levels of total polycyclic aromatic hydrocarbons and induced relatively higher levels of bulky aromatic DNA adducts than those derived from MS. The data indicate that TPM (MS + SS) from cigarettes appears to be more genotoxic than that from bidis and the contribution of tendu leaf (a non-tobacco bidi wrapper) to the generation of bulky aromatic DNA adducts appears to be significant, particularly in SS of bidis. Topical pretreatment with curcumin decreased the levels of TPM-derived adducts while pretreatment with dietary turmeric failed to show such protection.

Exocyclic malondialdehyde and aromatic DNA adducts in larynx tissues

Cigarette smoking and alcohol consumption, known to cause free radical generation and lipid peroxidation, are established risk factors for larynx cancer. Malondialdehyde (MDA) is a naturally occurring product of lipid peroxidation, capable of interacting with DNA to form exocyclic MDA–DNA adducts. In the present study, we investigated if the production of MDA–DNA adducts was increased in larynx cancer patients with respect to controls using 32P-DNA postlabeling techniques. Moreover, we examined the potential effects of cigarette smoking and alcohol consumption on endogenous DNA adducts. We then analyzed the same set of larynx tissues for the presence of 32P-postlabeled aromatic DNA adducts to determine more about the levels and types of adducts formed in the larynx. We observed that cancer patients tended to have increased levels of MDA and aromatic DNA adducts with respect to controls. In addition, smoking and alcohol were found to influence the formation of endogenous adducts in the larynx tissues. Finally, the amounts of endogenous adducts were found to be comparable to those observed for aromatic DNA adducts in the same set of larynx tissues. These findings imply that endogenous lesions, if not repaired, may contribute to larynx cancer development.

Multiple biomarkers study in painters in a shipyard in Korea

Shipbuilding workers are exposed to a variety of genotoxic compounds including polycyclic aromatic hydrocarbons (PAHs). A limited number of studies have been conducted to evaluate biomarkers related to PAH exposure in painters in the shipyard industry. We examined this in 208 workers recruited from a shipyard located in South Korea. Employees were grouped into three exposure groups: (1) 111 painters using coal tar paints, (2) 70 painters using general paints, and (3) 27 on-site controls using no paints. Levels of urinary 1-hydroxypyrene glucuronide (1-OHPG), as internal dose of PAH exposure, were measured by synchronous fluorescence spectroscopy. Glutathione S-transferase ( GST) M1 and T1 genotypes were assessed by a multiplex polymerase chain reaction (PCR)-based method, aromatic-DNA adducts in peripheral white blood cells were measured by 32 P -postlabeling, and glycophorin A (GPA) variant frequencies in red blood cells were assessed by flow cytometry. Information on demographic characteristics, smoking habits, diet, job title and use of personal protective equipment (e.g. respiratory and dermal) were collected by self-administered questionnaire. Average urinary 1-OHPG levels in coal tar paint (2.24 μmol/mol creatinine) and general paint (1.38 μmol/mol creatinine) users were significantly higher than in on-site controls (0.62 μmol/mol creatinine) ( P<0.001). Paint use, irrespective of the type of paints, and smoking (yes/no) were positively associated with urinary 1-OHPG levels, whereas green tea consumption (yes/no) was negatively associated with the 1-OHPG levels. No significant effect in the 1-OHPG levels were observed for the GSTM1 and GSTT1 genotypes. Aromatic-DNA adduct levels tended to be higher in coal tar paint users ( P=0.06) and painters ( P=0.07) compared to on-site controls. No differences in adduct levels were observed, between the two groups of painters, and the combined group showed greater adduct levels than on-site controls ( P=0.05). GPA mutation frequencies measured in 55 individuals with MN heterozygote genotypes were not significantly different among the three exposure groups, and no correlation was observed between urinary 1-OHPG levels and aromatic-DNA adducts or GPA mutation frequency. These results suggest that painters in the shipyard were exposed to significant amounts of PAHs and possibly to other genotoxic aromatic compounds, and that urinary 1-OHPG may be a potential biomarker of PAH exposure in this population.

Aromatic DNA adduct levels in coke oven workers: correlation with polymorphisms in genes (GSTP1, GSTM1, GSTT7 and CYPIA1 : Teixeira, J. P. et al. Mutation Research, 2002, 517, (1–2), 147–155

Aromatic DNA adduct levels in coke oven workers: correlation with polymorphisms in genes (GSTP1, GSTM1, GSTT7 and CYPIA1 : Teixeira, J. P. et al. Mutation Research, 2002, 517, (1–2), 147–155

Glutathione S-transferases and aromatic DNA adducts in smokers’ bronchoalveolar macrophages

Interindividual differences in the expression of carcinogen-metabolizing enzymes in the lung may modify the effective dose of tobacco carcinogens in this organ. We investigated the role of detoxifying glutathione S-transferases (GST) in the formation of aromatic DNA adducts in bronchoalveolar macrophages (BAM) of active smokers. The effect of GSTs on aromatic DNA adducts was studied separately and in combination with the PAH-metabolizing cytochrome P450 enzyme, CYP3A. GSTA, GSTM3, GSTP, and CYP3A protein levels were analyzed by Western blotting, GSTM1 and GSTP1 genotypes were determined by polymerase chain reaction (PCR) based methods, and numbers of aromatic DNA adducts were measured by nuclease P1 enhanced 32P-postlabeling method in BAM of 31 active smokers. No correlation was observed between GSTA or GSTP proteins or GSTM1 or GSTP1 genotypes and the level of aromatic DNA adducts. A high or medium expression level of GSTM3 was associated with a lower level of aromatic DNA adducts in the smokers who smoked less than 20 cigarettes per day, when the effect of GSTM3 was analyzed in combination with CYP3A (regression analysis; F 6,24=6.3, P<0.001). No protection by GSTM3 was observed in heavy smokers. High CYP3A levels, on the other hand, increased the number of DNA adducts regardless of the amount of smoking.

Lack of a distinct gradient in biomarker responses in small mammals collected at different distances from a highway.

This study describes biomarker effects in small mammals exposed to traffic emissions. Animals were collected at 10-50 m (site 1), 150-200 m (site 2), and 5 km (site 3) from a very busy highway (A2). To distinguish between routes of exposure, strictly carnivorous common shrews ( Sorex araneus) and predominantly herbivorous bank voles ( Clethrionomys glareolus) were collected. As a measure of exposure to polycyclic aromatic hydrocarbons (PAHs), aromatic DNA adduct levels were determined by (32)P-postlabeling techniques in tissue from heart, lung, and liver. Lead (Pb), cadmium (Cd), and copper (Cu) levels were analyzed in kidney as a measure of exposure to heavy metals. EROD and PROD activity and retinoid levels were determined in liver as effect biomarkers for exposure to PAHs and polyhalogenated aromatic hydrocarbons (PHAHs). Relatively high Cd levels in S. araneus and in particular elevated DNA adduct levels in C. glareolus indicated that small mammals at site 3 were exposed to more compounds than at sites 1 and 2 (3 > or = 1 > 2). The latter effect is probably due to an incidental and actual input of airborne pollutants that is deposited on plant surfaces. By consumption of above-ground vegetation, voles are chronically exposed to this pollution. Relatively high background input of PAHs probably hinders that the traffic-related gradient of airborne PAH concentrations found in an earlier study is reflected in DNA adduct levels in small mammals in the present study. Moreover, historical biomarkers for exposure to traffic emissions, such as increased kidney Pb levels, increased hepatic EROD activity, and disturbed hepatic vitamin A homeostasis are no longer applicable to indicate differences in exposure. This is a result of the ban on addition of Pb and chlorinated scavengers to gasoline and of cleaner combustion techniques, which were enforced by law over the past decade. Finally, it is advisable to use only juvenile small mammals for in situ monitoring of diffuse pollution because DNA adduct levels increased with age.

Aromatic DNA adduct levels in coke oven workers: correlation with polymorphisms in genes GSTP1, GSTM1, GSTT1 and CYP1A1

The aim of this study was to use DNA adducts levels, detected by 32 P -postlabelling, as a biomarker to assess human exposure to polycyclic aromatic hydrocarbons (PAHs) from a coke oven plant and explore the possible association between CYP1A1 MspI, GSTP1, GSTM1 and GSTT1 genotypes, and smoking status on bulky DNA adduct formation. A large amount of inter-individual variation in adduct level was observed among workers with the same job and the same smoking habits. No significant differences were observed in DNA adduct levels between the coke oven workers and control group. Smokers in the control group had significantly higher DNA adducts than the non-smokers in the same group (35.13±21.11 versus 11.18±8.00, per 10 8 nucleotides, P=0.003). In this group, the correlation between the level of DNA adducts and the cigarettes smoked was strongly significant ( r=0.70, P<0.0005), but no correlation was found among the coke oven workers. Among non-smokers there was a significant difference between the control group and the coke oven workers (11.18±8.00 versus 24.62±15.20, per 10 8 nucleotides, P=0.03). These results suggests that tobacco smoke could behave as a confounding factor for evaluation of DNA adducts arising from occupational exposure. The levels of DNA adducts in smokers not occupationally exposed to PAHs is dependent on the polymorphisms CYP1A1 MspI in the 3′ non-coding region (49.04±22.18 versus 25.85±15.87, per 10 8 nucleotides, P<0.05), but no effect was observed for the GST genotypes studied.

DNA-adducts and atherosclerosis: a study of accidental and sudden death males in the Czech Republic

Atherosclerosis and carcinogenesis may share some common mechanisms of the genotoxic action of exogenous compounds, such as polycyclic aromatic hydrocarbons (PAHs). The main objective of this study was to test the hypothesis that “bulky” aromatic DNA-adducts in smooth muscle cells (SMCs) of thoracic aortas taken at autopsy from sudden and accidental death male subjects, aged between 30 and 60 years ( N=133), are associated with the stage of atherosclerosis. The subjects with severe atherosclerotic damage were treated as “Cases” ( N=66). The subjects meeting diagnostic criteria for slight and moderate total atherosclerotic body damage were treated as “Controls” ( N=67). An additional objective of the study was to evaluate the effect of known atherogenic risk factors and possible modifiers of atherosclerotic changes, such as age, smoking, plasma lipid and antioxidant vitamin levels and some genetic susceptibility markers, e.g. polymorphisms of GSTM1, GSTT1, NAT2, CYP1A1 or apolipoprotein E ( APO E) genes. We found significantly higher DNA-adduct levels in “Cases” as compared with “Controls” (2.11±1.07 adducts/10 8 nucleotides versus 1.49±0.55 adducts/10 8 nucleotides, P<0.001). “Cases” were significantly older and had elevated heart weight and plasma cholesterol levels and a higher frequency of overweight subjects as compared with “Controls”. No significant differences in DNA-adduct levels between smokers and non-smokers within either group were detected. Multivariate logistic regression revealed that the “bulky” aromatic DNA-adducts, which are the most likely related to environmental exposure to genotoxic chemicals, remain a statistically significant predictor of the stage of atherosclerosis (OR=3.76, 95% CI=1.54–9.18, P=0.004) even after adjustment for age, smoking, obesity, heart weight and genetic susceptibility markers (GSTT1 and CYP1A1–MspI polymorphisms) that were also significant predictors. The fact that the “bulky” aromatic DNA-adduct levels predict the progression of atherosclerosis independently of smoking indicates that the formation of atherosclerotic plaques may also be initiated by environmental exposures other than tobacco smoke.

Aromatic DNA adducts and polymorphisms of CYP1A1, NAT2, and GSTM1 in breast cancer.

Previous studies by us and others have shown a significantly higher level of aromatic DNA adducts in normal adjacent breast tissue samples obtained from breast cancer patients than in those obtained from non-cancerous controls. The increased amount of DNA damage could be related to excess environmental carcinogen exposure and/or genetic susceptibility to such exposure. In the current study, we investigated the relationship between the levels of aromatic DNA adducts in breast tissues and polymorphisms of the drug-metabolizing genes cytochrome P4501A1 (CYP1A1), N-acetyltransferase-2 (NAT2), and glutathione S-transferase M1 (GSTM1), in 166 women having breast cancer. DNA adducts were measured using (32)P-postlabeling and information on smoking status was obtained from medical records. When pooled data of smokers and non-smokers were analyzed by multiple regression analyses, no significant correlation was found between the level of total DNA adducts and age, race, or polymorphisms of CYP1A1, GSTM1, and NAT2. The only significant predictor of the level of DNA adducts in breast tissues was smoking (P = 0.008). When data were analyzed separately in smokers and non-smokers, however, a significant gene-environment interaction was observed. Smokers with CYP1A1*1/*2 or *2/*2 genotypes had a significantly higher level of DNA adducts than those with the CYP1A1*1/*1 genotype. This effect was not seen among non-smokers. There was also a gene-gene interaction, as smokers with combined CYP1A1*1/*2 or CYP1A1*2/*2 genotypes and GSTM1 null had a much higher level of adducts than those with either CYP1A1 or GSTM1 polymorphism. Genetic polymorphisms of CYP1A1 and NAT2 were also significantly correlated with the frequency of certain types of DNA adducts. For example, a bulky benzo[a]pyrene (B[a]P)-like adduct was detected in 26% of the samples, the presence of which was not related to age, race, smoking status, or GSTM1 and NAT2 genotype. However, a significantly higher frequency of the B[a[P-like adduct was found in individuals having CYP1A1*1/*2 or *2/*2 genotypes than in those having the *1/*1 genotype (P = 0.04). In addition, individuals having slow NAT2 alleles had a significantly higher frequency of the typical smoking-related DNA adduct pattern, i.e. a diagonal radioactive zone (DRZ), than others did (P = 0.008). These findings suggest that polymorphisms of CYP1A1, GSTM1, and NAT2 significantly affect either the frequency or the level of DNA adducts in normal breast tissues of women having breast cancer, especially in smokers. Further large-scale studies are required to determine the exact role of these polymorphisms and types of DNA damage in breast cancer susceptibility.