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Dhanju S, Upadhyaya K, Rice CA, Pegan SD, Media J, Valeriote FA, Crich D. Synthesis, Cytotoxicity, and Genotoxicity of 10-Aza-9-oxakalkitoxin, an N,N,O-Trisubstituted Hydroxylamine Analog, or Hydroxalog, of a Marine Natural Product. J Am Chem Soc 2020; 142:9147-9151. [DOI: 10.1021/jacs.0c03763] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Sandeep Dhanju
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Kapil Upadhyaya
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
| | - Christopher A. Rice
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
| | - Scott D. Pegan
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
| | - Joseph Media
- Department of Internal Medicine, Division of Hematology and Oncology, Henry Ford Cancer Institute, Detroit, Michigan 48202, United States
| | - Frederick A. Valeriote
- Department of Internal Medicine, Division of Hematology and Oncology, Henry Ford Cancer Institute, Detroit, Michigan 48202, United States
| | - David Crich
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, United States,
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
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Dhanju S, Crich D. Synthesis of N,N,O-Trisubstituted Hydroxylamines by Stepwise Reduction and Substitution of O-Acyl N,N-Disubstituted Hydroxylamines. Org Lett 2016; 18:1820-3. [DOI: 10.1021/acs.orglett.6b00556] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sandeep Dhanju
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - David Crich
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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Blanke KL, Sacco JC, Millikan RC, Olshan AF, Luo J, Trepanier LA. Polymorphisms in the carcinogen detoxification genes CYB5A and CYB5R3 and breast cancer risk in African American women. Cancer Causes Control 2014; 25:1513-21. [PMID: 25225034 PMCID: PMC4216608 DOI: 10.1007/s10552-014-0454-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 07/31/2014] [Indexed: 11/29/2022]
Abstract
PURPOSE Cytochrome b 5 (encoded by CYB5A) and NADH cytochrome b 5 reductase (encoded by CYB5R3) detoxify aromatic and heterocyclic amine mammary carcinogens found in cigarette smoke. We hypothesized that CYB5A and CYB5R3 polymorphisms would be associated with breast cancer risk in women. METHODS We characterized the prevalence of 18 CYB5A and CYB5R3 variants in genomic DNA from African American (AfrAm) and Caucasian (Cauc) women from the Carolina Breast Cancer Study population (1,946 cases and 1,747 controls) and determined their associations with breast cancer risk, with effect modification by smoking. RESULTS A CYB5R3 variant, I1M+6T (rs8190370), was significantly more common in breast cancer cases (MAF 0.0238) compared with controls (0.0169, p = 0.039); this was attributable to a higher MAF in AfrAm cases (0.0611) compared with AfrAm controls (0.0441, p = 0.046; adjusted OR 1.41, CI 0.98-2.04; p = 0.062). When smoking was considered, I1M+6T was more strongly associated with breast cancer risk in AfrAm smokers (adjusted OR 2.10, 1.08-4.07; p = 0.028) compared with never smokers (OR = 1.21; 0.77-1.88; p for interaction = 0.176). I1M+6T and three additional CYB5R3 variants, -251T, I8-1676C, and *392C, as well as two CYB5A variants, 13G and I2-992T, were significantly more common in AfrAms compared with Caucs. CONCLUSIONS CYB5R3 I1M+6C>T should be considered in future molecular epidemiologic studies of breast cancer risk in AfrAms. Further, variants in CYB5A and CYB5R3 should be considered in the evaluation of other tumors in AfrAms that are associated with aromatic and heterocyclic amine exposures, to include prostate, bladder, and colon cancers.
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Affiliation(s)
- Kristina L. Blanke
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI
| | - James C. Sacco
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI
| | - Robert C. Millikan
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina, Chapel Hill, NC
| | - Andrew F. Olshan
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina, Chapel Hill, NC
| | - Jingchun Luo
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina, Chapel Hill, NC
| | - Lauren A. Trepanier
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI
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Genotoxicity and induction of DNA damage responsive genes by food-borne heterocyclic aromatic amines in human hepatoma HepG2 cells. Food Chem Toxicol 2013; 59:386-94. [DOI: 10.1016/j.fct.2013.06.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 06/14/2013] [Accepted: 06/18/2013] [Indexed: 01/07/2023]
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Rhoads K, Sacco JC, Drescher N, Wong A, Trepanier LA. Individual variability in the detoxification of carcinogenic arylhydroxylamines in human breast. Toxicol Sci 2011; 121:245-56. [PMID: 21447608 DOI: 10.1093/toxsci/kfr073] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Cytochrome b(5) (b5) and NADH cytochrome b(5) reductase (b5R) detoxify reactive hydroxylamine (NHOH) metabolites of known arylamine and heterocyclic amine mammary carcinogens. The aim of this study was to determine whether NHOH reduction for the prototypic arylamine 4-aminobiphenyl (4-ABP) was present in human breast and to determine whether variability in activity was associated with single nucleotide polymorphisms (SNPs) in the coding, promoter, and 3'untranslated region (UTR) regions of the genes encoding b5 (CYB5A) and b5R (CYB5R3). 4-ABP-NHOH reduction was readily detected in pooled human breast microsomes, with a K(m) (280μM) similar to that found with recombinant b5 and b5R, and a V(max) of 1.12 ± 0.19 nmol/min/mg protein 4-ABP-NHOH reduction varied 75-fold across 70 individual breast samples and correlated significantly with both b5 (80-fold variability) and b5R (14-fold) immunoreactive protein. In addition, wide variability in b5 protein expression was significantly associated with variability in CYB5A transcript levels, with a trend toward the same association between b5R and CYB5R3. Although a sample with a novel coding SNP in CYB5A, His22Arg, was found with low reduction and b5 expression, no other SNPs in either gene were associated with outlier activity or protein expression. We conclude that b5 and b5R catalyze the reduction of 4-ABP-NHOH in breast tissue, with very low activity, protein, and messenger RNA expression in some samples, which cannot be attributed to promoter, coding, or 3'UTR SNPs. Further studies are underway to characterize the transcriptional regulation of CYB5A and CYB5R3 and begin to understand the mechanisms of individual variability in this detoxification pathway.
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Affiliation(s)
- Keelia Rhoads
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706-1102, USA
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Immonen E, Serpi R, Vähäkangas K, Myllynen P. Responses of PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) in MCF-7 cells are culture condition dependent. Chem Biol Interact 2009; 182:73-83. [PMID: 19647730 DOI: 10.1016/j.cbi.2009.07.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 07/09/2009] [Accepted: 07/23/2009] [Indexed: 10/20/2022]
Abstract
To compare the effects of the food toxin 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP) and estradiol in hormone-responsive MCF-7 cells, the cells were exposed to different concentrations of either PhIP or estradiol. The effect of various culture conditions (e.g. phenol red, FBS, vehicle (DMSO/EtOH) and seeding density) on responses was studied. Cells were continuously grown with steroid-containing or -deprived medium, or switched from steroid-containing to -deprived medium for the experiments to minimize the effect of background estrogenicity. Effects of PhIP and estradiol on cell viability and proliferation were determined by ATP analysis and Ki-67 immunocytochemistry. Expression of estrogen receptor alpha, cell stress markers (p53 and ERK) and estrogen responsive proteins (c-myc and ERK) were immunoblotted. All concentrations of estradiol induced cell proliferation, viability and changes in protein expression, typical for estrogenic responses. PhIP, however, increased viability only at low concentrations and depending on culture conditions. No changes in protein expressions by PhIP were noted, not even when switching cells from steroid-containing to -deprived medium which down-regulated the expression of proteins at basal level. Vehicle affected significantly viability, especially after exposure to PhIP, but not protein expression while medium changes affected both. In conclusion, the effects of PhIP and estradiol in MCF-7 cells are dependent on culture conditions. The detected PhIP-induced changes are weaker compared to those induced by estradiol.
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Affiliation(s)
- E Immonen
- Institute of Biomedicine, Department of Pharmacology and Toxicology, University of Oulu, Oulu, Finland
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7
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Meat consumption, N-acetyl transferase 1 and 2 polymorphism and risk of breast cancer in Danish postmenopausal women. Eur J Cancer Prev 2008; 17:39-47. [DOI: 10.1097/cej.0b013e32809b4cdd] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kurian JR, Chin NA, Longlais BJ, Hayes KL, Trepanier LA. Reductive detoxification of arylhydroxylamine carcinogens by human NADH cytochrome b5 reductase and cytochrome b5. Chem Res Toxicol 2007; 19:1366-73. [PMID: 17040106 PMCID: PMC2516554 DOI: 10.1021/tx060106t] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heterocyclic and aromatic amine carcinogens are thought to lead to tumor initiation via the formation of DNA adducts, and bioactivation to arylhydroxylamine metabolites is necessary for reactivity with DNA. Carcinogenic arylhydroxylamine metabolites are cleared by a microsomal, NADH-dependent, oxygen-insensitive reduction pathway in humans, which may be a source of interindividual variability in response to aromatic amine carcinogens. The purpose of this study was to characterize the identity of this reduction pathway in human liver. On the basis of our findings with structurally similar arylhydroxylamine metabolites of therapeutic drugs, we hypothesized that the reductive detoxification of arylhydroxylamine carcinogens was catalyzed by NADH cytochrome b5 reductase (b5R) and cytochrome b5 (cyt b5). We found that reduction of the carcinogenic hydroxylamines of the aromatic amine 4-aminobiphenyl (4-ABP; found in cigarette smoke) and the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP; found in grilled meats) was indeed catalyzed by a purified system containing only human b5R and cyt b5. Specific activities were 56-346-fold higher in the purified system as compared to human liver microsomes (HLM), with similar Michaelis-Menten constants (K(m) values) in both systems. The stoichiometry for b5R and cyt b5 that yielded the highest activity in the purified system was also similar to that found in native HLM ( approximately 1:8 to 1:10). Polyclonal antisera to either b5R or cyt b5 significantly inhibited N-hydroxy-4-aminobiphenyl (NHOH-4-ABP) reduction by 95 and 89%, respectively, and immunoreactive cyt b5 protein content in individual HLM was significantly correlated with individual reduction of both NHOH-4-ABP and N-hydroxy-PhIP (NHOH-PhIP). Finally, titration of HLM into the purified b5R/cyt b5 system did not enhance the efficiency of reduction activity. We conclude that b5R and cyt b5 are together solely capable of the reduction of arylhydroxylamine carcinogens, and we further hypothesize that this pathway may be a source of individual variability with respect to cancer susceptibility following 4-ABP or PhIP exposure.
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Affiliation(s)
| | | | | | | | - Lauren A. Trepanier
- Address correspondence to: Lauren A. Trepanier, Department of Medical Sciences, UW-Madison School of Veterinary Medicine, 2015 Linden Dr, Madison, WI, 53706. Tel. 608 265−9022; Fax 608 265−8020;
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Kitamura Y, Umemura T, Kanki K, Ishii Y, Kuroiwa Y, Masegi T, Nishikawa A, Hirose M. Lung as a new target in rats of 2-amino-3-methylimidazo[4,5-f]quinoline carcinogenesis: results of a two-stage model initiated with N-bis(2-hydroxypropyl)nitrosamine. Cancer Sci 2006; 97:368-73. [PMID: 16630133 PMCID: PMC11158155 DOI: 10.1111/j.1349-7006.2006.00191.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The effects of IQ on the promotion stage of DHPN-induced lung carcinogenesis and contributions of oxidative stress were investigated in rats. Groups of 20 male 6-week-old F344 rats were given 0.1% DHPN in their drinking water for 2 weeks for initiation. From the age of 9 weeks, they were treated with 0, 150 and 300 p.p.m. of IQ in the diet for 27 weeks. Control rats were similarly fed 300 p.p.m. IQ or basal diet alone without the preceding initiation. IQ clearly (P < 0.01) enhanced the multiplicity of lung tumors in a dose-dependent manner (DHPN alone, 3.63 +/- 1.80; DHPN +150 p.p.m. IQ, 11.50 +/- 5.04; DHPN +300 p.p.m. IQ, 18.83 +/- 4.58 [no./rat]). In addition, the incidence of lung tumors in the 300 p.p.m. IQ alone group (25%) was significantly (P < 0.05) higher than that in the non-treatment group (0%). In a second experiment, male rats were given IQ at doses of 0 and 300 p.p.m. in the diet for one week in order to analyze 8-OHdG formation, levels of TBARS and BrdU-LI in the lungs. There were no changes in 8-OHdG or TBARS levels, but significant elevation of BrdU-LI occurred in the IQ administration group. The overall data clearly indicate that IQ is a potent lung carcinogen in rats, in which oxidative stress may not be involved in lung carcinogenesis.
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Affiliation(s)
- Yasuki Kitamura
- Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
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Hiraku Y, Sekine A, Nabeshi H, Midorikawa K, Murata M, Kumagai Y, Kawanishi S. Mechanism of carcinogenesis induced by a veterinary antimicrobial drug, nitrofurazone, via oxidative DNA damage and cell proliferation. Cancer Lett 2004; 215:141-50. [PMID: 15488632 DOI: 10.1016/j.canlet.2004.05.016] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2003] [Revised: 05/17/2004] [Accepted: 05/18/2004] [Indexed: 01/10/2023]
Abstract
Nitrofurazone, a veterinary antimicrobial drug, causes mammary and ovarian tumors in animals. We investigated the mechanisms of carcinogenesis by nitrofurazone. Nitrofurazone significantly stimulated the proliferation of estrogen-dependent MCF-7 cells. Nitrofurazone caused Cu(II)-mediated damage to 32P-5'-end-labeled DNA fragments obtained from human genes only when cytochrome P450 reductase was added. DNA damage was inhibited by catalase and bathocuproine. DNA damage was preferably induced at the 5'-ACG-3' sequence, a hotspot of the p53 gene. These findings suggest that nitrofurazone metabolites are involved in tumor initiation through oxidative DNA damage and nitrofurazone itself enhances cell proliferation, leading to promotion and/or progression in carcinogenesis.
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Affiliation(s)
- Yusuke Hiraku
- Department of Environmental and Molecular Medicine, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan
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Sakano K, Oikawa S, Hiraku Y, Kawanishi S. Mechanism of metal-mediated DNA damage induced by a metabolite of carcinogenic acetamide. Chem Biol Interact 2004; 149:52-9. [PMID: 15356919 DOI: 10.1016/j.cbi.2004.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Acetamide is carcinogenic in rats and mice. To clarify the mechanism of carcinogenesis by acetamide, we investigated DNA damage by and acetamide metabolite, acetohydroxamic acid (AHA), using 32P-5'-end-labeled DNA fragments. AHA treated with amidase induced DNA damage in the presence of Cu(II) and displayed a similar DNA cleavage pattern of hydroxylamine. DNA damage was inhibited by both catalase and bathocuproine, suggesting that H2O2 and Cu(I) are involved. Carboxy-PTIO, a specific scavenger of nitric oxide (NO), partially inhibited DNA damage. The amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) by amidase-treated AHA was similar to that by hydroxylamine. ESR spectrometry revealed that amidase-treated AHA as well as hydroxylamine generated NO in the presence of Cu(II). From these results, it has been suggested that AHA might be converted into hydroxylamine by amidase. These results suggest that metal-mediated DNA damage mediated by amidase-catalyzed hydroxylamine generation plays an important role in the carcinogenicity of acetamide.
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Affiliation(s)
- Katsuhisa Sakano
- Department of Environmental and Molecular Medicine, Mie University School of Medicine, Edobashi, Tsu, Japan
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Turesky RJ, Vouros P. Formation and analysis of heterocyclic aromatic amine–DNA adducts in vitro and in vivo. J Chromatogr B Analyt Technol Biomed Life Sci 2004; 802:155-66. [PMID: 15036007 DOI: 10.1016/j.jchromb.2003.10.053] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The detection and quantification of heterocyclic aromatic amine (HAA)-DNA adducts, critical biomarkers in interspecies extrapolation of toxicity data for human risk assessment, remains a challenging analytical problem. The two main analytical methods currently in use to screen for HAA-DNA adducts are the 32P-postlabeling assay and mass spectrometry, using either accelerated mass spectrometry (AMS) or liquid chromatography and electrospray ionization mass spectrometry (LC-ESI-MS). In this review, the principal methods to synthesize and characterize DNA adducts, and the methods applied to measure HAA-DNA adduct in vitro and vivo are discussed.
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Affiliation(s)
- Robert J Turesky
- Division of Chemistry, National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA.
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Yang H, Holcroft J, Glickman BW, de Boer JG. Conjugated linoleic acid inhibits mutagenesis by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in the prostate of Big Blue rats. Mutagenesis 2003; 18:195-200. [PMID: 12621076 DOI: 10.1093/mutage/18.2.195] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a potent mutagen and carcinogen formed at high temperature during the cooking of meat. PhIP induces tumors in the colon and prostate of male rats and in the mammary gland of female rats and has been associated with the etiology of human cancers. We have recently demonstrated that PhIP induces mutations in the prostate in Big Blue transgenic rats. In the current study we have examined the effect of a dietary anti-carcinogen, conjugated linoleic acid (CLA), on PhIP-induced mutagenesis in the prostate. CLA is a mixture of positional and geometric isomers of linoleic acid and has been reported to inhibit various chemical-induced cancers in rodent models. Fifty day old male Big Blue rats were fed a standard diet containing 100 p.p.m. PhIP for 47 days, which induced a mutation frequency of 14.6 x 10(-5) in the prostate, 5.1-fold higher than that of controls. The addition of 1% CLA (w/w) in the diet starting 1 week prior to exposure to PhIP decreased PhIP-induced mutagenesis by 38% (P = 0.03). The predominant class of mutation induced by PhIP is -1 frameshifts involving the loss of G:C base pairs, followed by G:C-->T:A transversions and G:C-->A:T transitions. Addition of CLA to the diet significantly changed the PhIP-induced mutation spectrum; notably, -1 frameshifts and G:C-->A:T transitions were selectively inhibited, suggesting involvement of mismatch repair. This is the first report to show the protective effect of CLA against PhIP-induced mutagenesis in the prostate on both mutation frequency and mutational spectrum. The inhibitory effect of CLA against PhIP-induced mutagenicity suggests a possibility for its application in human chemoprevention studies.
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Affiliation(s)
- Haiyan Yang
- Department of Biology, University of Victoria, Victoria, BC V8W 3N5, Canada
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McDiarmid HM, Douglas GR, Coomber BL, Josephy PD. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mutagenesis in cultured Big Blue rat mammary epithelial and fibroblast cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2002; 39:245-253. [PMID: 11921195 DOI: 10.1002/em.10059] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Epithelial cells are the primary site of carcinogenesis in most tissues, including the mammary gland. As an alternative to the study of mutation induction in whole tissues in vivo, we have established Big Blue transgenic rat cell lines from the mammary epithelium (BBR/ME) and the mammary stroma (BBR/MFib), to permit a comparison of their mutagenic responses to carcinogens. We previously demonstrated their responsiveness to the alkylating agent N-ethyl-N-nitrosourea (ENU) (McDiarmid H et al. [2001]: Mutat Res 497:39-47). Here, we examined the responses of cultured epithelial and stromal cells to the protein pyrolysis product and mammary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Rat hepatic S9 was used as a source of bioactivation enzymes. Mutant induction (cII locus) and clonogenic survival were measured as a function of PhIP concentration. PhIP mutagenicity was observed in the fibroblast cells, but the greater toxicity of PhIP to the epithelial cells prevented a definitive evaluation of mutagenicity. Since PhIP may be detoxified by conjugation with glutathione, we measured glutathione levels and glutathione-S-transferase expression and activities in both cell lines. The epithelial cells had higher glutathione-S-transferase enzyme activity and protein expression than did the fibroblast cell line. Because the epithelial cells were more sensitive to toxicity, glutathione conjugation evidently plays only a minor role in PhIP toxicity and mutagenicity in our cell lines.
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Affiliation(s)
- Heather M McDiarmid
- Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario, Canada
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15
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DeBruin LS, Martos PA, Josephy PD. Detection of PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) in the milk of healthy women. Chem Res Toxicol 2001; 14:1523-8. [PMID: 11712910 DOI: 10.1021/tx015556u] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
An increased risk of breast cancer has been observed in women who consume "very well-done" meats. Heterocyclic amines are mutagenic and carcinogenic pyrolysis products formed during high temperature cooking of meats. In the present study, human milk samples were analyzed for PhIP, one of the most abundant dietary heterocyclic amine. A protocol was developed with a mixed-mode cation exchange sorbent for the extraction of heterocyclic amines from milk. Milk samples were acquired from healthy Canadian women. With LC/MS analysis and the method of isotope dilution for quantification, levels of PhIP were determined in human milk samples. PhIP was detected in 9 of the 11 milk samples, at levels as high as 59 pg/mL (ppt). No PhIP was detected in the milk of the vegetarian donor. Detection of PhIP in milk indicates that ductal mammary epithelial cells are directly exposed to this carcinogen, suggesting that heterocyclic amines are possible human mammary carcinogens.
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Affiliation(s)
- L S DeBruin
- Guelph-Waterloo Centre for Graduate Work in Chemistry (GWC(2)), Department of Chemistry & Biochemistry, Laboratory Services, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Liu CS, Ko LY, Lim PS, Kao SH, Wei YH. Biomarkers of DNA damage in patients with end-stage renal disease: mitochondrial DNA mutation in hair follicles. Nephrol Dial Transplant 2001; 16:561-5. [PMID: 11239032 DOI: 10.1093/ndt/16.3.561] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND DNA damage was noted in patients with end-stage renal disease (ESRD). Mitochondrial DNA (mtDNA) mutations have been proposed as a genomic biomarker in the process of human ageing, degenerative diseases and carcinogenesis. METHODS Polymerase chain reaction (PCR) techniques were applied to detect mtDNA deletions in hair follicles, an appendage of skin, from 162 patients with ESRD. RESULTS The incidences of the 4977 bp deletion of mtDNA in hair follicles were found to increase with age in normal control and ESRD patients. As compared with normal subjects, ESRD patients had 3.5, 2.3, 2.7, 2.3 and 1.4 times higher incidences of the 4977 bp deletion of mtDNA in the age groups of 20-30, 31-40, 41-50, 51-60 and 61-70 years, respectively. Moreover, the difference in the proportion of mtDNA with the 4977 bp deletion was statistically significant between ESRD patients and normal subjects >50 years of age. CONCLUSION We suggest that the 4977 bp deletion of mtDNA in hair follicles may serve as one of the tissue biomarkers of genetic instability of the mitochondrial genome in ESRD patients.
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Affiliation(s)
- C S Liu
- Department of Internal Medicine, Kuang Tien General Hospital, Taichung, Taiwan
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Rylander T, Neve EP, Ingelman-Sundberg M, Oscarson M. Identification and tissue distribution of the novel human cytochrome P450 2S1 (CYP2S1). Biochem Biophys Res Commun 2001; 281:529-35. [PMID: 11181079 DOI: 10.1006/bbrc.2001.4390] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
With the aid of the htgs and dbEST databases, a novel cytochrome P450 cDNA was found by homology searches, and the corresponding gene was identified on chromosome 19. Nested PCR was used to amplify a full-length sequence of 1515 bp. The predicted 504 amino acid sequence displays 38--49% identity with CYP2 family members and the protein was designated CYP2S1. mRNA dot blot analysis demonstrated high expression levels in trachea, lung, stomach, small intestine, and spleen. The expression pattern was confirmed by Northern blot, which also revealed a single transcript of approximately 2.4 kb. Western blot analysis, using an antiserum directed against the C-terminus of the enzyme, detected a protein in human lung with the same mobility as recombinant CYP2S1. Subcellular fractionation and immunostaining revealed that CYP2S1 was localized in the endoplasmic reticulum. We conclude that CYP2S1 represents a novel abundantly expressed human P450 with potential importance for extrahepatic xenobiotic metabolism.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibody Specificity
- Base Sequence
- Blotting, Northern
- Blotting, Western
- Cell Line, Transformed
- Cloning, Molecular
- Cytochrome P-450 Enzyme System/genetics
- Cytochrome P-450 Enzyme System/immunology
- Cytochrome P-450 Enzyme System/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Recombinant
- Female
- Humans
- Immune Sera/immunology
- Isoenzymes/genetics
- Isoenzymes/immunology
- Isoenzymes/metabolism
- Lung/metabolism
- Male
- Microscopy, Fluorescence
- Molecular Sequence Data
- Oxygenases/genetics
- Oxygenases/immunology
- Oxygenases/metabolism
- Phylogeny
- Plasmids/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Analysis, DNA
- Tissue Distribution
- Transfection
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Affiliation(s)
- T Rylander
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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18
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Felix K, Kovalchuk AL, Park SS, Coleman AE, Ramsay ES, Qian M, Kelliher KA, Jones GM, Ried T, Bornkamm GW, Janz S. Inducible mutagenesis in TEPC 2372, a mouse plasmacytoma cell line that harbors the transgenic shuttle vector lambdaLIZ. Mutat Res 2001; 473:121-36. [PMID: 11166031 DOI: 10.1016/s0027-5107(00)00143-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The plasmacytoma cell line, TEPC 2372, was derived from a malignant plasma cell tumor that developed in the peritoneal cavity of a BALB/c mouse that harbored the transgenic shuttle vector for the assessment of mutagenesis in vivo, lambdaLIZ. TEPC 2372 was found to display the typical features of a BALB/c plasmacytoma. It consisted of pleomorphic plasma cells that secreted a monoclonal immunoglobulin (IgG2b/lambda), was initially dependent on the presence of IL-6 to grow in cell culture, contained a hyperdiploid chromosome complement with a tendency to undergo tetraploidization, and harbored a constitutively active c-myc gene by virtue of a T(6;15) chromosomal translocation. TEPC 2372 was further characterized by the ability to respond to in vitro exposure with 4-NQO (4-nitroquinoline-1-oxide), an oxidative model mutagen, with a vigorous dose-dependent increase in mutagenesis that peaked at a 7.85-fold elevation of mutant rates in lambdaLIZ when compared to background mutant rates in untreated controls. Cotreatment with 4-NQO and BSO (buthionine sulfoximine), a glutathione-depleting compound that causes endogenous oxidative stress, resulted in a 9.03-fold increase in the mutant frequency in lambdaLIZ. These results demonstrated that TEPC 2372, the malignant plasma cell counterpart of the lambdaLIZ-based in vivo mutagenesis assay, may be useful as an in vitro reference point for the further elucidation of oxidative mutagenesis in lymphoid tissues.
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Affiliation(s)
- K Felix
- Laboratory of Genetics, DBS, NCI, Building 37, Room 2B10, Bethesda, MD 20892-4255, USA.
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19
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Malfatti MA, Kulp KS, Knize MG, Davis C, Massengill JP, Williams S, Nowell S, MacLeod S, Dingley KH, Turteltaub KW, Lang NP, Felton JS. The identification of [2-(14)C]2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine metabolites in humans. Carcinogenesis 1999; 20:705-13. [PMID: 10223203 DOI: 10.1093/carcin/20.4.705] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
[2-(14)C]2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine ([14C]PhIP), a putative human carcinogenic heterocyclic amine found in well-done cooked meat, was administered orally to three colon cancer patients undergoing a partial colonectomy. Forty-eight to seventy-two hours prior to surgery, subjects received a 70-84 microg dose of 14C. Urine and blood were analyzed by HPLC for PhIP and PhIP metabolites. Metabolites were identified based on HPLC co-elution with authentic PhIP metabolite standards, mass spectral analysis and susceptibility to enzymatic cleavage. In two subjects, approximately 90% of the administered [14C]PhIP dose was eliminated in the urine, whereas in the other, only 50% of the dose was found in the urine. One subject excreted three times more radioactivity in the first 4 h than did the others. Twelve radioactive peaks associated with PhIP were detected in the urine samples. The relative amount of each metabolite varied by subject, and the amounts of each metabolite within subjects changed over time. In all three subjects the most abundant urinary metabolite was identified as 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine-N2-glucuron ide (N-hydroxy-PhIP-N2-glucuronide), accounting for 47-60% of the recovered counts in 24 h. PhIP accounted for <1% of the excreted radiolabel in all three patients. Other metabolites detected in the urine at significant amounts were 4-(2-amino-1-methylimidazo[4,5-b]pyrid-6-yl)phenyl sulfate, N-hydroxy-PhIP-N3-glucuronide and PhIP-N2-glucuronide. In the plasma, N-hydroxy-PhIP-N2-glucuronide accounted for 60, 18 and 20% of the recovered plasma radioactivity at 1 h post PhIP dose in subjects 1, 2 and 3 respectively. Plasma PhIP was 56-17% of the recovered dose at 1 h post exposure. The relatively high concentration of N-hydroxy-PhIP-N2-glucuronide and the fact that it is an indicator of bioactivation make this metabolite a potential biomarker for PhIP exposure and activation. Determining the relative differences in PhIP metabolites among individuals will indicate metabolic differences that may predict individual susceptibility to carcinogenic risk from this suspected dietary carcinogen.
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Affiliation(s)
- M A Malfatti
- Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, CA 94551, USA
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20
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Dubuisson JG, Gaubatz JW. Bioactivation of the proximal food mutagen 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-OH-PhIP) to DNA-binding species by human mammary gland enzymes. Nutrition 1998; 14:683-6. [PMID: 9760588 DOI: 10.1016/s0899-9007(98)00106-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We have investigated phase II activation of the food-derived mutagen 2-hydroxyamino-1-methyl-6-phenyl[4,5-b]pyridine (N-OH-PhIP) by cytosolic acetyltransferase, sulfotransferase, and tRNA synthetase/kinase enzymes from human breast tissue. Cytosol from homogenates of mammary gland tissue obtained from breast-reduction surgery or mastectomy was incubated with and without enzyme-specific cofactors, and mutagen binding of calf thymus DNA was quantified by 32P-postlabeling. In addition, microsomal fractions of mammary epithelial cells from some individuals were examined for prostaglandin H synthetase activation of N-OH-PhIP. Our results show that all four enzymes can participate in activating N-OH-PhIP, thus inducing PhIP-DNA adduct formation in human mammary cells. However, not all individuals exhibited all these activities; instead each individual showed a combination of one or more activation pathways. The present findings demonstrate that the human mammary gland has the capacity to metabolically activate a dietary mutagen by several enzyme systems, including acetyltransferase, sulfotransferase, tRNA synthetase/kinase, and prostaglandin hydroperoxidase catalysis.
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Affiliation(s)
- J G Dubuisson
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, USA
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21
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Abstract
Development of breast cancer in women is dependent on diverse factors, including genetic predisposition, exposure to both exogenous and endogenous chemicals, which can modulate initiation, promotion and progression of this disease, and the timing of exposure to these agents. Several compounds--including 16 alpha-hydroxyestrone (16 alpha-OHE1), catecholestrogens, and aromatic amines--have been proposed as initiators of mammary carcinogenesis in humans; however, their role as genotoxins is unconfirmed. Lifetime exposure to estrogens has been established as an important risk factor for breast cancer, and it has been suggested that xenoestrogens may directly add to the hormonal risk or indirectly increase risk by decreasing 2-hydroxyestrone (2-OHE1)/16 alpha-OHE1 metabolite ratios. Results of recent studies suggest that chemical-induced modulation of 2-OHE1/16 alpha-OHE1 metabolite ratios is not predictive of xenoestrogens or mammary carcinogens. Moreover, based on current known dietary intakes of natural and xenoestrogenic/antiestrogenic chemicals, it is unlikely that xenoestrogens contribute significantly to a woman's overall lifetime exposure to estrogens. More information is required on the identities and serum levels of both natural and xenoendocrine active compounds, their concentrations in serum, and the mammary gland and levels of these compounds at critical periods of exposure.
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Affiliation(s)
- S H Safe
- Veterinary Physiology and Pharmacology, Texas A&M University, College Station 77843-4466, USA.
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23
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Lawson T, Kolar C, Reyes T. Mutagenicity of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) when activated by hamster pancreatic duct epithelial cells: a chemopreventive role for glutathione. Mutat Res 1997; 375:73-8. [PMID: 9129680 DOI: 10.1016/s0027-5107(96)00252-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have shown a role for glutathione (GSH) in the detoxification of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) using mutagenicity in V79 cells as the end-point. Immortalized hamster pancreas duct epithelial cells (CK cells) were used to metabolize PhIP in this assay. Intracellular GSH concentrations were lowered by treatment with buthionine sulfoximine (BSO) and were raised by treatment with sodium sulfite. BSO treatment (10 mM, 4 h) reduced the GSH concentration in V79 cells from 18 +/- 1 to 6 +/- 1 nmol/mg protein, 4 h after treatment. The mutation frequency of PhIP in these V79 cells rose from 15 +/- 2 to 34 +/- 4 mutants/10(6) survivors in BSO-treated V79 cells. In a related experiment both CK and V79 cells were treated with sulfite. Sulfite treatment (2 mM, 4 h) produced a greater reduction in PhIP mutagenicity when the V79 cells were treated with sulfite (from 15 +/- 2 to 3 +/- 1 mutants/10(6) survivors) than when the CK cells were treated (from 15 +/- 2 to 7 +/- 2 mutants/10(6) survivors). These data show a relationship between intracellular GSH concentration and the mutagenicity of PhIP.
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Affiliation(s)
- T Lawson
- Eppley Institute for Research in Cancer and Allied Disease, University of Nebraska Medical Center, Omaha 68198-6805, USA
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24
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Wohlin P, Zeisig M, Gustafsson JA, Möller L. 32-P-HPLC analysis of DNA adducts formed in vitro and in vivo by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline, utilizing an improved adduct enrichment procedure. Chem Res Toxicol 1996; 9:1050-6. [PMID: 8870995 DOI: 10.1021/tx960050a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
DNA adducts of 2-amino-1 methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-diMeIQx), synthesized in vitro with calf thymus DNA and formed in vivo in the male Wistar rat, were enriched from digested DNA by butanol extraction before 32P-postlabeling. The recovery after butanol enrichment was 79% and 32% for in vitro modified PhIP- and 4,8-diMeIQx-DNA adducts, respectively. Crude postlabeling mixtures were chromatographically separated by high-performance liquid chromatography with on-line 32P-detection (32P-HPLC). The major PhIP- and 4,8-diMeIQx-DNA adducts formed in vitro cochromatographed with the respective pdGp-C8 adduct standard. 32P-HPLC was also used to separate hydrolysates of in vitro formed PhIP-DNA and 4,8-diMeIQx-DNA that had been 32P-postlabeled under ATP-deficient conditions. The adduct recovery of the ATP-deficient method relative to the improved butanol enrichment procedure was 29% and 59% for total PhIP-DNA and 4,8-diMeIQx-DNA adducts, respectively. Simplified DNA adduct patterns were obtained when the postlabeling mixtures were incubated with nuclease P1, suggesting incomplete DNA hydrolysis. After nuclease P1 treatment, the major DNA adducts of PhIP and 4,8-diMeIQx formed in vitro cochromatographed with the respective pdG-C8 adduct standard. In vivo PhIP formed what appeared to be multiple DNA adducts; however, after nuclease P1 treatment the PhIP-associated peaks were concentrated into a single peak cochromatographing with pdG-C8-PhIP, 4,8-diMeIQx formed multiple DNA adducts in vivo. Nuclease P1 treatment resulted in two 4,8-diMeIQx related peaks, one cochromatographing with pdG-C8-4,8-diMeIQx. The second peak remains unidentified. The improved workup procedures in combination with the high resolution and reproducibility of the 32P-HPLC system should be useful for characterization of PhIP- and 4,8-diMeIQx-DNA adducts in DNA modified by complex mixtures.
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Affiliation(s)
- P Wohlin
- Department of Bioscience, Karolinska Institute, Huddinge, Sweden
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