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Longitudinal Study of Urinary Phenanthrene Metabolite Ratios: Effect of Smoking on the Diol Epoxide Pathway

The Cancer Center and Transdisciplinary Tobacco Use Research Center, University of Minnesota, Minneapolis, Minnesota

Requests for reprints: Stephen S. Hecht, The Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street Southeast, Minneapolis, MN 55455. Phone: 612-624-7604; Fax: 612-626-5135. E-mail: hecht002{at}umn.edu

	Abstract

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We have proposed that urinary phenanthrene metabolites could be used in a carcinogen metabolite phenotyping approach to identify individuals who may be susceptible to cancer induction by polycyclic aromatic hydrocarbons (PAH). In support of this proposal, we have developed methods for quantitation of r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene (PheT) and phenanthrols (HOPhe) in human urine. PheT is the end product of the diol epoxide metabolic activation pathway of PAH, whereas HOPhe are considered as detoxification products. In this study, we investigated the longitudinal consistency of these metabolites over time in smokers and nonsmokers and compared their levels. Twelve smokers and 10 nonsmokers provided urine samples daily for 7 days, then weekly for 6 weeks. Levels of PheT, HOPhe, and PheT/HOPhe ratios were relatively constant in most individuals, with mean coefficients of variation ranging from 29.3% to 45.7%. There were no significant changes over time in levels of the metabolites or in ratios. These results indicate that a single urine sample should be sufficient when comparing phenanthrene metabolites in different groups. PheT/HOPhe ratios were significantly higher in smokers than in nonsmokers, showing that smoking induces the diol epoxide metabolic activation pathway of phenanthrene. This finding is consistent with previous studies indicating that inducibility of PAH metabolism contributes to cancer risk in smokers. (Cancer Epidemiol Biomarkers Prev 2005;14(12):2969–74)

	Introduction

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Polycyclic aromatic hydrocarbons (PAH) are "reasonably anticipated to be human carcinogens" (1). Abundant evidence supports the role of PAHs as important causes of lung cancer and, perhaps, other cancers in smokers (2, 3). Many PAHs are potent locally acting carcinogens, and fractions of cigarette smoke condensate enriched in these compounds are tumorigenic. DNA adducts of benzo(a)pyrene (BaP), a prototypical PAH, have been identified in the lungs of smokers, and the spectrum of mutations seen in the p53 gene isolated from lung tumors is similar to that induced by PAH and their diol epoxide metabolites (4). PAHs are also believed to be causative agents for cancers of the lung in coke production workers and cancer of the skin in workers exposed to coal tars, shale oil, and soot (5, 6).

PAHs require metabolic activation to exert their carcinogenic effects (7). The principal route of metabolic activation of BaP that results in DNA adduct formation in human tissues proceeds by way of anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE; Fig. 1; refs. 8-10). A sizeable body of evidence supports this metabolic activation pathway as the major one for many other PAHs as well (9). There are also other mechanisms of BaP metabolic activation, but the evidence that these contribute to DNA adduct formation in humans is presently more limited (11, 12). Competing with PAH metabolic activation are a variety of detoxification pathways, including direct hydroxylation to form phenols, conjugation of epoxides and diol epoxides with glutathione, and glucuronidation of dihydrodiols (7). Multiple enzymes are involved in the metabolic activation and detoxification of PAH. Cytochromes P450 and epoxide hydrolase are involved in both activation and detoxification, whereas glutathione S-transferases and UDP-glucuronosyl-transferases are involved mainly in detoxification (7). Many studies have investigated the role of polymorphisms in these enzymes as modifiers of cancer risk in people exposed to PAHs. The results of these studies have been somewhat inconsistent, although certain genotype variant combinations may lead to higher risk (13-16). Our goal has been to develop a carcinogen metabolite phenotyping approach, which would capture all genetic and environmental influences on PAH metabolism by actually measuring their metabolites in urine. We initiated this work by developing a method for analysis in human urine of r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (Fig. 1), but the levels of this metabolite were so low that the method would not be practical for application in epidemiologic studies (17). Therefore, we turned our attention to phenanthrene (Fig. 1), the simplest PAH with a bay region, a feature closely associated with carcinogenicity. Phenanthrene occurs in higher concentrations in the environment than does BaP, and its metabolites are more plentiful in urine (18). The metabolites of higher molecular weight PAHs are excreted mainly in feces, detracting from their use as biomarkers. Although phenanthrene is not considered to be carcinogenic, its pathways of metabolism are similar to those of BaP and other PAHs. Thus, as illustrated in Fig. 1, phenanthrene is metabolized to a diol epoxide in a manner similar to BaP (9, 19). Phenanthrene is also converted to phenanthrols (HOPhe) metabolically (20). The end product of the diol epoxide pathway is r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene (PheT; ref. 21). We propose that a ratio of PheT (as a marker of metabolic activation) to HOPhe (as a marker of detoxification) would be characteristic of a given individual's ability to metabolically activate or detoxify PAHs. One major goal in this study was to determine the longitudinal consistency of this ratio in a person. This would provide essential information with respect to the design of epidemiologic studies using this biomarker. A second goal was to compare the ratio in smokers and nonsmokers.

View larger version (18K): [in this window] [in a new window] [Download PPT slide]   Figure 1. Metabolism of BaP and phenanthrene (Phe) to bay region diol epoxides (BPDE and anti-PheDE) and tetraols (trans, anti-BaP-tetraol and PheT) and of phenanthrene to phenanthrols (1-HOPhe, 2-HOPhe, 3-HOPhe, 4-HOPhe, and 9-HOPhe).

	Materials and Methods

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Smokers were recruited through flyers posted at the University of Minnesota campus and near campus, and an advertisement in a hospital newspaper for a study of smokers who were not intending to quit. Interested participants called the Tobacco Use Research Center and were told that the study would involve submission of urine samples over a 7-week period to assess levels of cancer-causing agents. They were screened for current or recent bladder or urinary tract infection, and smokers had to smoke at least five cigarettes per day. Subjects who met the criteria (12 of 20 screened) were enrolled in the study. Before enrollment, subjects were asked to sign a consent form and then complete a demographic, smoking history, second-hand exposure, and physical health questionnaire.

Urine samples were dropped off at the Tobacco Use Research Center every 2 days during the seven-consecutive-day collection period and once weekly thereafter. Smokers were asked to record daily number of cigarettes they smoked during this urine collection period. At each visit, current use of medication was recorded, and alveolar carbon monoxide levels were assessed. Subjects were paid for each urine sample with a bonus for completing the study.

Nonsmokers were healthy volunteers recruited from Cancer Center employees, and urine collection procedures were similar to smokers. All subjects approached participated.

Analysis of Urine
Urinary PheT and 1-HOPhe, 2-HOPhe, 3-HOPhe, and 4-HOPhe were determined by gas chromatography-mass spectrometry as described previously, except that [D₁₀]PheT was used as internal standard in the PheT analysis (20, 21). Creatinine was assayed by Fairview University Medical Center Diagnostic Laboratories (Minneapolis, MN) using Vitros CREA slides.

Statistical Analysis
In the statistical analysis, we included PheT, the end product of the diol epoxide metabolic activation pathway, 3-HOPhe, and total HOPhe. 3-HOPhe was chosen because the internal standard for the HOPhe assay is [ring-¹³C₆]3-HOPhe, and measurement of 3-HOPhe is therefore highly accurate and precise. Total HOPhe (the sum of 1-HOPhe, 2-HOPhe, 3-HOPhe, and 4-HOPhe) indicates total HOPhe formation. In our hands, 9-HOPhe cannot be quantified accurately but has been reported to be a minor urinary metabolite by others (18).

Because the distribution of levels of PheT, HOPhe, and PheT/HOPhe ratios were positively skewed, we transformed all measurements to the log scale in our analysis and calculated geometric means.

Statistical analyses of PheT, HOPhe, and PheT/HOPhe ratio were based on ANOVA with repeated measurements. Calculations were done using SAS, version 8. These ANOVA analyses included one fixed factor (smokers versus nonsmokers) and one repeated factor (time: days 1-7, then weeks 2-7). We also included in each the interaction term between these two factors (smoking by time). The time effect would help to investigate the longitudinal consistency of these metabolites and their ratio. The fixed effect of smoking would help to investigate the effect of smoking on the diol epoxide pathway. The inclusion of an interaction factor would help to determine, if smokers and nonsmokers are different, whether their difference is constant over time.

	Results

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The 10 nonsmokers ranged in age from 23 to 50 years (mean ± SD, 35 ± 9 years); two were female. The 12 smokers smoked from 5 to 40 cigarettes per day (mean, 20 ± 10), had 0.5 to 20 pack-years of smoking (mean, 12 ± 9 pack-years), and ranged in age from 19 to 62 years (mean, 39 ± 12 years). Nine of the smokers were female.

Coefficients of variation (CV) for PheT, 3-HOPhe, total HOPhe and the ratios PheT/3-HOPhe and PheT/total HOPhe over the 49-day period for smokers and nonsmokers are summarized in Table 1. Variation in PheT levels was greater than that in levels of 3-HOPhe or total HOPhe. Five of 12 smokers and 2 of 10 nonsmokers had CV for PheT which exceeded 50%, whereas 3 of 12 smokers and 1 of 10 nonsmokers had CV of >50% for 3-HOPhe, and 3 of 12 smokers and 0 of 10 nonsmokers had CV of >50% for total HOPhe. Three of 12 smokers had >50% CV in PheT/3-HOPhe or PheT/total HOPhe ratios; these three individuals also had >50% CV in PheT levels. Three of 10 nonsmokers had CV of >50% for PheT/3-HOPhe or PheT/total HOPhe ratios; one of these also had >50% variation in PheT levels. Overall CV ranged from 33.4 ± 14.3% (±SD; 3-HOPhe) to 40.5 ± 24.2% (PheT) in smokers and 29.3 ± 11.8% (3-HOPhe) to 45.7 ± 20.3% (PheT/total HOPhe) in nonsmokers. CV for PheT/3-HOPhe and PheT/total HOPhe ratios were 37.3 ± 17.1% and 36.3 ± 18.4% in smokers, respectively, whereas the corresponding figures in nonsmokers for these two ratios were 44.0 ± 20.8% and 45.7 ± 20.3%.

Variation in the PheT/total HOPhe ratio in each of the 12 smokers and 10 nonsmokers is illustrated in Fig. 2. Much of the variation was accounted for by a few values (e.g., day 2 in smoker number 7, day 42 in smoker number 8, or day 35 in nonsmoker number 9). These outlier values were not due to variation in the mass spectrometric analysis.

View larger version (36K): [in this window] [in a new window] [Download PPT slide]   Figure 2. Individual variation in PheT/total HOPhe ratios in (A) 12 smokers and (B) 10 nonsmokers.

Correlations among PheT and HOPhe are summarized in Table 2. Correlation coefficients for PheT versus 3-HOPhe and PheT versus total HOPhe were generally in the range of 0.6 to 0.8 in smokers, with weaker relationships being observed in nonsmokers. 3-HOPhe and total HOPhe were highly correlated in both smokers and nonsmokers.

View larger version (17K): [in this window] [in a new window] [Download PPT slide]   Figure 3. PheT/total HOPhe ratio in smokers and nonsmokers over the course of the study.

	Discussion

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Variations in PheT levels with time in a given individual were generally greater than variations in 3-HOPhe or total HOPhe. Thus, mean CV for PheT were 40.5% and 43.0% in smokers and nonsmokers, respectively, whereas the corresponding values for 3-HOPhe were 33.4% and 29.3%, and for total HOPhe 34.9% and 31.8%. The greater variation in PheT than 3-HOPhe or total HOPhe is not due to exposure differences, because both metabolites are formed from phenanthrene. Furthermore, there was no difference in CV between smokers and nonsmokers, although smokers are exposed to higher amounts of phenanthrene than nonsmokers. It is also not likely to be due to analytic differences because analytic variation in the PheT and HOPhe assays have been reported to be 16.2% for PheT and 5.7% to 22% for HOPhe (20, 21). The most probable explanation is that multiple enzymes are involved in PheT formation. Levels of PheT will be influenced by cytochrome P450s, epoxide hydrolases, UDP-glucuronosyl transferases, glutathione S-transferases, and possibly other enzymes (7, 22). In contrast, formation of HOPhe is catalyzed predominantly by cytochrome P450s (19). There could be diverse genetic, environmental, and dietary influences on the activity of these enzymes, thereby leading to more variation in PheT levels than in HOPhe. A further consequence of the smaller variation in HOPhe than PheT was the strong correlation between 3-HOPhe and total HOPhe, whereas the correlation between PheT and phenanthrols was weaker.

Levels of urinary PheT in an individual result from exposure plus metabolic activation of phenanthrene. Because phenanthrene always occurs in a mixture with other PAH and because many of these carcinogens are metabolically activated by the same mechanism that produces PheT, levels of PheT should indicate exposure plus metabolic activation of PAHs. Our main interest is to detect those individuals who are susceptible to PAH carcinogenesis at a given level of exposure. The PheT/3-HOPhe or PheT/total HOPhe ratios should correct for exposure and give a more precise indication of individual differences in metabolism. Levels of PheT and the ratios both should be applicable in epidemiologic studies: PheT as a measure of exposure plus metabolic activation and ratios as an indication of differences in metabolism at a given level of exposure. It is not clear at present which measure may provide a better indication of cancer susceptibility upon PAH exposure.

A potentially important finding of this study was the significantly higher PheT/total HOPhe ratio in smokers than in nonsmokers (Fig. 3). It is well established that cigarette smoking induces cytochromes P450 1A1, 1A2, and 1B1 through interactions of PAHs, and possibly other cigarette smoke constituents, with the aryl hydrocarbon receptor (AHR; refs. 23-28). Approximately 10% of people have a high AHR inducibility phenotype (25, 26). A number of studies have associated this phenotype with a higher risk for lung cancer and other cancers in tissues, which come in direct contact with cigarette smoke, although there seem to be many confounding factors, and the results are not entirely consistent (23-26). Cytochromes P450 1A1, 1A2, and 1B1 are involved in both the metabolic activation and detoxification of PAHs (29-35). One series of studies showed a relationship between induction of these enzymes in smokers and BPDE-DNA adducts in the lung (36, 37). However, to our knowledge, there have been no previous studies which have examined the consequences of induction of cytochromes P450 1A1, 1A2, and 1B1 by cigarette smoke with respect to activation versus detoxification of PAHs in humans. Our results show that the diol epoxide metabolic activation pathway of phenanthrene is induced to a greater extent than the phenol detoxification pathway in smokers (Fig. 3). This finding is consistent with the proposed relationship between P450 1A1 and 1B1 induction and increased cancer risk. The greater induction of the diol epoxide than the phenol metabolism pathway is logical because P450 1A1, 1A2, and 1B1 are involved in two steps in diol epoxide formation but only one step in phenol formation (Fig. 1). In addition, some studies indicate that epoxide hydrolase, which is also involved in diol epoxide formation, is induced in smokers, but others show no change (38-41).

A limitation of this study was its relatively small size, involving only 12 smokers and 10 nonsmokers. This was dictated by the multiple sampling (13 per individual) and the relative complexity of the separate analyses for PheT and HOPhe. We are developing more rapid methods of analysis of these metabolites, which will facilitate larger studies. A second limitation is that phenanthrene is being used as a surrogate for carcinogenic PAHs and urinary metabolites as a surrogate for cellular changes relevant to cancer. We do not know if high PheT levels indicate correspondingly high levels of formation of BPDE and BPDE-DNA adducts in lung or other tissues. This is currently under investigation.

In summary, the results of this study indicate that levels of the phenanthrene metabolites PheT and HOPhe in urine are relatively constant over time in a given individual, supporting their use as biomarkers of PAH metabolism. We also showed that the diol epoxide metabolic activation pathway of phenanthrene is induced in smokers, consistent with an important role for PAHs in smoking-induced cancer.

	Acknowledgments

 
We thank the subjects for participation in this study and Bob Carlson for editorial assistance.

	Footnotes

 
Grant support: National Cancer Institute grants CA-92025 and DA-013333 and ACS grant RP-00-138 (S.S. Hecht). Mass spectrometry and statistics were carried out in the core facilities of The Cancer Center, University of Minnesota, supported in part by National Cancer Institute grant CA-77598.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Note: S.S. Hecht is an American Cancer Society research professor.

Received 6/ 1/05; revised 9/ 9/05; accepted 9/27/05.

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. U.S. Department of Health and Human Services: Public Health Service National Toxicology Program. Report on carcinogens. 10th ed. Research Triangle Park (NC): U.S. Department of Health and Human Services; 2002. p. 201–4.
2. Hecht SS. Tobacco carcinogens, their biomarkers, and tobacco-induced cancer. Nat Rev Cancer 2003;3:733–44.[CrossRef][Medline]
3. Hecht SS. Tobacco smoke carcinogens and lung cancer. J Natl Cancer Inst 1999;91:1194–210.[Abstract/Free Full Text]
4. Pfeifer GP, Denissenko MF, Olivier M, et al. Tobacco smoke carcinogens, DNA damage and p53 mutations in smoking-associated cancers. Oncogene 2002;21:7435–51.[CrossRef][Medline]
5. IARC. Polynuclear aromatic compounds, Part 3. Industrial exposures in aluminum production, coal gasification, coke production, and iron and steel founding. IARC monographs on the evaluation of the carcinogenic risk of chemicals to humans. Vol. 34. Lyon (France): IARC; 1984. p. 101–31.
6. IARC. Polynuclear aromatic compounds, Part 4. Bitumens, coal-tars and derived products, shale oils and soots. IARC monographs on the evaluation of the carcinogenic risk of chemicals to humans. Vol. 35. Lyon (France): IARC; 1985. p. 83–241.
7. Cooper CS, Grover PL, Sims P. The metabolism and activation of benzo[a]pyrene. Prog Drug Metab 1983;7:295–396.
8. Conney AH, Chang RL, Jerina DM, et al. Studies on the metabolism of benzo[a]pyrene and dose-dependent differences in the mutagenic profile of its ultimate carcinogenic metabolite. Drug Metab Rev 1994;26:125–63.[Medline]
9. Thakker DR, Yagi H, Levin W, et al. Polycyclic aromatic hydrocarbons: metabolic activation to ultimate carcinogens. In: Anders MW, editor. Bioactivation of foreign compounds. New York: Academic Press, Inc.; 1985. p. 177–242.
10. Kriek E, Rojas M, Alexandrov K, et al. Polycyclic aromatic hydrocarbon-DNA adducts in humans: relevance as biomarkers for exposure and cancer risk. Mutat Res 1998;400:215–31.[Medline]
11. Casale GP, Singhal M, Bhattacharya S, et al. Detection and quantification of depurinated benzo[a]pyrene-adducted DNA bases in the urine of cigarette smokers and women exposed to household coal smoke. Chem Res Toxicol 2001;14:192–201.[CrossRef][Medline]
12. Yu D, Berlin JA, Penning TM, et al. Reactive oxygen species generated by PAH o-quinones cause change-in-function mutations in p53. Chem Res Toxicol 2002;15:832–42.[CrossRef][Medline]
13. Benhamou S, Lee WJ, Alexandrie AK, et al. Meta- and pooled analyses of the effects of glutathione S-transferase M₁ polymorphisms and smoking on lung cancer risk. Carcinogenesis 2002;23:1343–50.[Abstract/Free Full Text]
14. Caporaso NE. Why have we failed to find the low penetrance genetic constituents of common cancers? Cancer Epidemiol Biomarkers Prev 2002;11:1544–9.[Free Full Text]
15. Bartsch H, Nair U, Risch A, et al. Genetic polymorphism of CYP genes, alone or in combination, as a risk modifier of tobacco-related cancers. Cancer Epidemiol Biomarkers Prev 2000;9:3–28.[Abstract/Free Full Text]
16. Houlston RS. CYP1A1 polymorphisms and lung cancer risk: a meta-analysis. Pharmacogenetics 2000;10:105–14.[CrossRef][Medline]
17. Simpson CD, Wu MT, Christiani DC, et al. Determination of r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene in human urine by gas chromatography-negative ion chemical ionization-mass spectrometry. Chem Res Toxicol 2000;13:271–80.[CrossRef][Medline]
18. Jacob J, Seidel A. Biomonitoring of polycyclic aromatic hydrocarbons in human urine. J Chromatogr B Analyt Technol Biomed Life Sci 2002;778:31–47.[Medline]
19. Shou M, Korzekwa KR, Krausz KW, et al. Regio- and stereo-selective metabolism of phenanthrene by twelve cDNA-expressed human, rodent, and rabbit cytochromes P-450. Cancer Lett 1994;83:305–13.[CrossRef][Medline]
20. Carmella SG, Chen M, Yagi H, et al. Analysis of phenanthrols in human urine by gas chromatography-mass spectrometry: potential use in carcinogen metabolite phenotyping. Cancer Epidemiol Biomarkers Prev 2004;13:2167–74.[Abstract/Free Full Text]
21. Hecht SS, Chen M, Yagi H, et al. r-1,t-2,3,c-4-Tetrahydroxy-1,2,3,4-tetrahydrophenanthrene in human urine: a potential biomarker for assessing polycyclic aromatic hydrocarbon metabolic activation. Cancer Epidemiol Biomarkers Prev 2003;12:1501–8.[Abstract/Free Full Text]
22. Baird WM, Ralston SL. Carcinogenic polycyclic aromatic hydrocarbons. In: Bowden GT, Fischer SM, editors. Comprehensive toxicology: chemical carcinogens and anticarcinogens. Vol. 12. New York: Elsevier Science Ltd.; 1997. p. 171–200.
23. IARC. Tobacco smoking. IARC monographs on the evaluation of the carcinogenic risk of chemicals to humans. Vol. 38. Lyon (France): IARC; 1986. p. 186–8.
24. IARC. Tobacco smoke and involuntary smoking. IARC monographs on the evaluation of carcinogenic risks to humans. Vol. 83. Lyon (France): IARC; 2004. p. 1009.
25. Nebert DW, Dalton TP, Okey AB, et al. Role of aryl hydrocarbon receptor-mediated induction of the CYP1 enzymes in environmental toxicity and cancer. J Biol Chem 2004;279:23847–50.[Abstract/Free Full Text]
26. Nebert DW, McKinnon RA, Puga A. Human drug-metabolizing enzyme polymorphisms: effects on risk of toxicity and cancer. DNA Cell Biol 1996;15:273–80.[Medline]
27. Kim JH, Sherman ME, Curriero FC, et al. Expression of cytochromes P450 1A1 and 1B1 in human lung from smokers, non-smokers, and ex-smokers. Toxicol Appl Pharmacol 2004;199:210–9.[CrossRef][Medline]
28. Port JL, Yamaguchi K, Du B, et al. Tobacco smoke induces CYP1B1 in the aerodigestive tract. Carcinogenesis 2004;25:2275–81.[Abstract/Free Full Text]
29. Wattenberg LW, Loub WD. Inhibition of polycyclic aromatic hydrocarbon-induced neoplasia by naturally occurring indoles. Cancer Res 1978;38:1410–3.[Abstract/Free Full Text]
30. Uno S, Dalton TP, Derkenne S, et al. Oral exposure to benzo[a]pyrene in the mouse: detoxication by inducible cytochrome P450 is more important than metabolic activation. Mol Pharmacol 2004;65:1225–37.[Abstract/Free Full Text]
31. Kleiner HE, Vulimiri SV, Hatten WB, et al. Role of cytochrome p4501 family members in the metabolic activation of polycyclic aromatic hydrocarbons in mouse epidermis. Chem Res Toxicol 2004;17:1667–74.[CrossRef][Medline]
32. Shimada T, Hayse CL, Yamazaki H, et al. Activation of chemically diverse procarcinogens by human cytochrome P450 1B1. Cancer Res 1996;56:2979–84.[Abstract/Free Full Text]
33. Bauer E, Guo Z, Ueng YF, et al. Oxidation of benzo[a]pyrene by recombinant human cytochrome P450 enzymes. Chem Res Toxicol 1995;8:136–42.[CrossRef][Medline]
34. Shou M, Korzekwa KR, Crespi CL, et al. The role of 12 cDNA-expressed human, rodent, and rabbit cytochromes P450 in the metabolism of benzo[a]pyrene and benzo[a]pyrene trans-7,8-dihydrodiol. Mol Carcinog 1994;10:159–68.[Medline]
35. Shimada T, Gillam EMJ, Oda Y, et al. Metabolism of benzo[a]pyrene to trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene by recombinant human cytochrome P450 1B1 and purified liver epoxide hydrolase. Chem Res Toxicol 1999;12:623–9.[CrossRef][Medline]
36. Alexandrov K, Rojas M, Geneste O, et al. An improved fluorometric assay for dosimetry of benzo(a)pyrene diol- epoxide-DNA adducts in smokers' lung: comparisons with total bulky adducts and aryl hydrocarbon hydroxylase activity. Cancer Res 1992;52:6248–53.[Abstract/Free Full Text]
37. Rojas M, Camus AM, Alexandrov K, et al. Stereoselective metabolism of (–)-benzo[a]pyrene-7,8-diol by human lung microsomes and peripheral blood lymphocytes: effect of smoking. Carcinogenesis 1992;13:929–33.[Abstract/Free Full Text]
38. Petruzzelli S, Camus AM, Carrozzi L, et al. Long-lasting effects of tobacco smoking on pulmonary drug-metabolizing enzymes: a case-control study on lung cancer patients. Cancer Res 1988;48:4695–700.[Abstract/Free Full Text]
39. Oesch F, Schmassmann H, Ohnhaus E, et al. Monooxygenase, epoxide hydrolase, and glutathione-S-transferase activities in human lung. Variation between groups of bronchogenic carcinoma and non-cancer patients and interindividual differences. Carcinogenesis 1980;1:827–35.[Abstract/Free Full Text]
40. Willey JC, Coy EL, Frampton MW, et al. Quantitative RT-PCR measurement of cytochromes p450 1A1, 1B1, and 2B7, microsomal epoxide hydrolase, and NADPH oxidoreductase expression in lung cells of smokers and nonsmokers. Am J Respir Cell Mol Biol 1997;17:114–24.[Abstract/Free Full Text]
41. Omiecinski CJ, Aicher L, Holubkov R, et al. Human peripheral lymphocytes as indicators of microsomal epoxide hydrolase activity in liver and lung. Pharmacogenetics 1993;3:150–8.[Medline]

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