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da Silva Junior FC, Felipe MBMC, Castro DEFD, Araújo SCDS, Sisenando HCN, Batistuzzo de Medeiros SR. A look beyond the priority: A systematic review of the genotoxic, mutagenic, and carcinogenic endpoints of non-priority PAHs. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 278:116838. [PMID: 33714059 DOI: 10.1016/j.envpol.2021.116838] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 02/06/2021] [Accepted: 02/21/2021] [Indexed: 06/12/2023]
Abstract
Knowledge of the toxic potential of polycyclic aromatic hydrocarbons (PAHs) has increased over time. Much of this knowledge is about the 16 United States - Environmental Protection Agency (US - EPA) priority PAHs; however, there are other US - EPA non-priority PAHs in the environment, whose toxic potential is underestimated. We conducted a systematic review of in vitro, in vivo, and in silico studies to assess the genotoxicity, mutagenicity, and carcinogenicity of 13 US - EPA non-priority parental PAHs present in the environment. Electronic databases, such as Science Direct, PubMed, Scopus, Google Scholar, and Web of Science, were used to search for research with selected terms without time restrictions. After analysis, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, 249 articles, published between 1946 and 2020, were selected and the quality assessment of these studies was performed. The results showed that 5-methylchrysene (5-MC), 7,12-dimethylbenz[a]anthracene (7,12-DMBA), cyclopenta[cd]pyrene (CPP), and dibenzo[al]pyrene (Db[al]P) were the most studied PAHs. Moreover, 5-MC, 7,12-DMBA, benz[j]aceanthrylene (B[j]A), CPP, anthanthrene (ANT), dibenzo[ae]pyrene (Db[ae]P), and Db[al]P have been reported to cause mutagenic effects and have been being associated with a risk of carcinogenicity. Retene (RET) and benzo[c]fluorene (B[c]F), the least studied compounds, showed evidence of a strong influence on the mutagenicity and carcinogenicity endpoints. Overall, this systematic review provided evidence of the genotoxic, mutagenic, and carcinogenic endpoints of US - EPA non-priority PAHs. However, further studies are needed to improve the future protocols of environmental analysis and risk assessment in severely exposed populations.
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Affiliation(s)
- Francisco Carlos da Silva Junior
- Department of Cell Biology and Genetics, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil; Graduate Program in Molecular Biology and Biochemistry, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil
| | | | - Denis Elvis Farias de Castro
- Department of Cell Biology and Genetics, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil; Graduate Program in Molecular Biology and Biochemistry, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil
| | - Sinara Carla da Silva Araújo
- Department of Cell Biology and Genetics, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil; Graduate Program in Molecular Biology and Biochemistry, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil
| | - Herbert Costa Nóbrega Sisenando
- Department of Cell Biology and Genetics, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil; Department of Clinical and Toxicological Analysis, Health Sciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil
| | - Silvia Regina Batistuzzo de Medeiros
- Department of Cell Biology and Genetics, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil; Graduate Program in Molecular Biology and Biochemistry, Biosciences Center, Federal University of Rio Grande Do Norte, Natal, RN, Brazil.
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Cavalieri E, Rogan E. The molecular etiology and prevention of estrogen-initiated cancers: Ockham's Razor: Pluralitas non est ponenda sine necessitate. Plurality should not be posited without necessity. Mol Aspects Med 2014; 36:1-55. [PMID: 23994691 PMCID: PMC3938998 DOI: 10.1016/j.mam.2013.08.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/05/2013] [Accepted: 08/06/2013] [Indexed: 12/22/2022]
Abstract
Elucidation of estrogen carcinogenesis required a few fundamental discoveries made by studying the mechanism of carcinogenesis of polycyclic aromatic hydrocarbons (PAH). The two major mechanisms of metabolic activation of PAH involve formation of radical cations and diol epoxides as ultimate carcinogenic metabolites. These intermediates react with DNA to yield two types of adducts: stable adducts that remain in DNA unless removed by repair and depurinating adducts that are lost from DNA by cleavage of the glycosyl bond between the purine base and deoxyribose. The potent carcinogenic PAH benzo[a]pyrene, dibenzo[a,l]pyrene, 7,12-dimethylbenz[a]anthracene and 3-methylcholanthrene predominantly form depurinating DNA adducts, leaving apurinic sites in the DNA that generate cancer-initiating mutations. This was discovered by correlation between the depurinating adducts formed in mouse skin by treatment with benzo[a]pyrene, dibenzo[a,l]pyrene or 7,12-dimethylbenz[a]anthracene and the site of mutations in the Harvey-ras oncogene in mouse skin papillomas initiated by one of these PAH. By applying some of these fundamental discoveries in PAH studies to estrogen carcinogenesis, the natural estrogens estrone (E1) and estradiol (E2) were found to be mutagenic and carcinogenic through formation of the depurinating estrogen-DNA adducts 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua. These adducts are generated by reaction of catechol estrogen quinones with DNA, analogously to the DNA adducts obtained from the catechol quinones of benzene, naphthalene, and the synthetic estrogens diethylstilbestrol and hexestrol. This is a weak mechanism of cancer initiation. Normally, estrogen metabolism is balanced and few estrogen-DNA adducts are formed. When estrogen metabolism becomes unbalanced, more catechol estrogen quinones are generated, resulting in higher levels of estrogen-DNA adducts, which can be used as biomarkers of unbalanced estrogen metabolism and, thus, cancer risk. The ratio of estrogen-DNA adducts to estrogen metabolites and conjugates has repeatedly been found to be significantly higher in women at high risk for breast cancer, compared to women at normal risk. These results indicate that formation of estrogen-DNA adducts is a critical factor in the etiology of breast cancer. Significantly higher adduct ratios have been observed in women with breast, thyroid or ovarian cancer. In the women with ovarian cancer, single nucleotide polymorphisms in the genes for two enzymes involved in estrogen metabolism indicate risk for ovarian cancer. When polymorphisms produce high activity cytochrome P450 1B1, an activating enzyme, and low activity catechol-O-methyltransferase, a protective enzyme, in the same woman, she is almost six times more likely to have ovarian cancer. These results indicate that formation of estrogen-DNA adducts is a critical factor in the etiology of ovarian cancer. Significantly higher ratios of estrogen-DNA adducts to estrogen metabolites and conjugates have also been observed in men with prostate cancer or non-Hodgkin lymphoma, compared to healthy men without cancer. These results also support a critical role of estrogen-DNA adducts in the initiation of cancer. Starting from the perspective that unbalanced estrogen metabolism can lead to increased formation of catechol estrogen quinones, their reaction with DNA to form adducts, and generation of cancer-initiating mutations, inhibition of estrogen-DNA adduct formation would be an effective approach to preventing a variety of human cancers. The dietary supplements resveratrol and N-acetylcysteine can act as preventing cancer agents by keeping estrogen metabolism balanced. These two compounds can reduce the formation of catechol estrogen quinones and/or their reaction with DNA. Therefore, resveratrol and N-acetylcysteine provide a widely applicable, inexpensive approach to preventing many of the prevalent types of human cancer.
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Affiliation(s)
- Ercole Cavalieri
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA; Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, 984388 Nebraska Medical Center, Omaha, NE 68198-4388, USA.
| | - Eleanor Rogan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA; Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, 984388 Nebraska Medical Center, Omaha, NE 68198-4388, USA.
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Kowalczyk MC, Walaszek Z, Kowalczyk P, Kinjo T, Hanausek M, Slaga TJ. Differential effects of several phytochemicals and their derivatives on murine keratinocytes in vitro and in vivo: implications for skin cancer prevention. Carcinogenesis 2009; 30:1008-15. [PMID: 19329757 PMCID: PMC2691143 DOI: 10.1093/carcin/bgp069] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 03/18/2009] [Accepted: 03/21/2009] [Indexed: 11/12/2022] Open
Abstract
The purpose of our study was to investigate in vitro the potential cancer preventive properties of several phytochemicals, i.e. grape seed extract (GSE), resveratrol (RES), ursolic acid (URA), ellagic acid (ELA), lycopene and N-acetyl-L-cysteine (NAC) to define the mechanisms by which these compounds may inhibit murine skin carcinogenesis. We measured quenching of peroxyl, superoxide and hydroxyl radicals by these phytochemicals. We also used adenosine triphosphate (ATP) bioluminescence, Caspase-Glo 3/7 and P450-Glo (CYP1A1 and CYP1B1) assays to study antiproliferative, proapoptotic and CYP-inhibiting effects of the phytochemicals. We next determined their effects on a 4 week inflammatory hyperplasia assay using 7,12-dimethylbenz[a]anthracene-induced murine skin carcinogenesis model to further understand their mechanism of action. Three murine keratinocyte cell lines, i.e. non-tumorigenic (3PC), papilloma-derived (MT1/2) and squamous cell carcinoma-derived (Ca3/7) cell lines, were used in in vitro assays. We have found that GSE, ELA and RES are potent scavengers of peroxyl and superoxide radicals. Statistically significant effects on activities of caspase-3 and -7 were observed only after GSE and URA treatments. All tested compounds protected cells from hydrogen peroxide-induced DNA damage. Using a short-term complete carcinogenesis assay, we have found that all selected compounds caused marked decreases of epidermal thickness and (except RES) reduced percentages of mice with mutation in codon 61 of Ha-ras oncogene. In conclusion, differential effects of tested phytochemicals on events and processes critical for the growth inhibition of keratinocytes in vitro and in vivo indicate that combinations of tested compounds may, in the future, better counteract both tumor initiation and tumor promotion/progression.
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Affiliation(s)
| | - Zbigniew Walaszek
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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Kleiner HE, Vulimiri SV, Hatten WB, Reed MJ, Nebert DW, Jefcoate CR, DiGiovanni J. Role of cytochrome p4501 family members in the metabolic activation of polycyclic aromatic hydrocarbons in mouse epidermis. Chem Res Toxicol 2005; 17:1667-74. [PMID: 15606143 DOI: 10.1021/tx049919c] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are known to be activated by the cytochrome P450 (P450) 1 family. However, the precise role of individual P4501 family members in PAH bioactivation remains to be fully elucidated. We therefore investigated the formation of PAH-DNA adducts in the epidermis of Cyp1a2(-/-), Cyp1b1(-/-), and Ahr(-/-) knockout mice. A panel of different PAHs was used, ranging in carcinogenic potency. Mice were treated topically on the dorsal skin with the following tritium-labeled PAHs: dibenzo[a,l]pyre-ne (DB[a,l]P), 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (B[a]P), dibenzo[a,h]anthracene (DB[a,h]A), benzo[g]chrysene (B[g]C), and benzo[c]phenanthrene (B[c]P). At 24 h after treatment, mice (two male and two female mice per group) were sacrificed, and epidermal DNA was isolated and hydrolyzed with DNase I; subsequently, DNA adducts were quantitated by liquid scintillation counting. In the DB[a,l]P-treated mice, levels of DNA adducts were significantly lower in Cyp1a2(-/-) and Cyp1b1(-/-) mice by 57 and 46%, respectively, as compared to wild-type (WT) mice (C57BL/6 background). The levels of DB[a,l]P DNA adducts formed in Ahr(-/-) mice were 26% lower, but this was not statistically significant. The levels of DMBA-DNA adducts in Cyp1a2(-/-) mice were not different than the WT mice but were significantly lower in Cyp1b1(-/-) and Ahr(-/-) mice by 64 and 52%, respectively. DMBA-DNA adduct samples were further analyzed by HPLC following further digestion to deoxyribonucleosides. HPLC analysis of individual DMBA-DNA adducts revealed differences in the ratio of syn-DMBA-diol epoxide- to anti-DMBA-diol epoxide-derived adducts in the Ahr(-/-) and Cyp1b1(-/-) mice. The ratio of syn-/anti-derived adducts in WT mice was 0.49. This ratio was 0.23 in the Cyp1b1(-/-) mice and 0.87 in the Ahr(-/-) mice. In contrast to the results with DB[a,l]P and DMBA, the levels of B[a]P-, DB[a,h]A-, B[g]C-, and B[c]P-DNA adducts were significantly lower in Ahr(-/-) mice by 73, 75, 50, and 81%, respectively, as compared to WT mice but were not significantly lower in the Cyp1a2(-/-) or Cyp1b1(-/-) mice. Collectively, these and other results support a role for both P4501A1 and P4501B1 in the bioactivation of DMBA; P4501A2, P4501B1, and possibly P4501A1 in the bioactivation of DB[a,l]P; and P4501A1 in the bioactivation of B[a]P, DB[a,h]A, B[g]C, and B[c]P in mouse epidermis. Furthermore, in the metabolic activation of DMBA in mouse epidermis, P4501B1 shows a preference for the formation of syn-DMBA-diol epoxide adducts, whereas P4501A1 shows a preference for the formation of anti-DMBA-diol epoxide adducts.
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Affiliation(s)
- Heather E Kleiner
- Department of Carcinogenesis, Science Park-Research Division, University of Texas M.D. Anderson Cancer Center, Smithville, Texas, USA
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Horn J, Lehner AF, Flesher JW. Rapid induction of mammary cancer by repeated subcutaneous injection of the trans-3,4-dihydrodiol of 7,12-dimethylbenz[a]anthracene in the female Sprague–Dawley rat. Cancer Lett 2005; 220:155-60. [PMID: 15766590 DOI: 10.1016/j.canlet.2004.07.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Revised: 07/30/2004] [Accepted: 07/31/2004] [Indexed: 11/27/2022]
Abstract
The oral administration of a single 20mg dose of 7,12-dimethylbenz[a]anthracene regularly and rapidly induces mammary cancer in 50 day-old Sprague-Dawley female rats [Experimental Leukemia and Mammary Cancer, 1979, p. 74]. Several mechanisms by which 7,12-dimethylbenz[a]anthracene induces mammary cancer have been proposed and various derivatives have been implicated as possible proximate or ultimate electrophilic and carcinogenic forms of this hydrocarbon. Here we show that 7,12-dimethylbenz[a]anthracene-trans-3,4-dihydrodiol rapidly induces mammary cancer by repeated subcutaneous injection in a high proportion of female Sprague-Dawley rats without malignancies at the site of injection, whereas its more lipid soluble diacetate derivative induced injection site sarcomas in addition to distal mammary cancers. By contrast, repeated subcutaneous injection of 7,12-dimethylbenz[a]anthracene and its 7-meso-aldehyde derivative induced subcutaneous sarcoma in most, if not all, rats and a few mammary cancers.
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Affiliation(s)
- Jamie Horn
- Experimental Cancer Research Laboratory, Department of Molecular and Biomedical Pharmacology, MS305, Albert B. Chandler Medical Center, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA
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Ignatowicz E, Balana B, Vulimiri SV, Szaefer H, Baer-Dubowska W. The effect of plant phenolics on the formation of 7,12-dimethylbenz[a]anthracene-DNA adducts and TPA-stimulated polymorphonuclear neutrophils chemiluminescence in vitro. Toxicology 2003; 189:199-209. [PMID: 12832153 DOI: 10.1016/s0300-483x(03)00148-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Phenolics, common plant constituents, form up an important part of human diet and are considered potential chemopreventive agents. In the present study, structurally diverse phenolics, such as tannic acid, protocatechuic acid, chlorogenic acid and resveratrol, were investigated for their inhibitory effects on covalent binding of 7,12-dimethylbenz[a]anthracene (DMBA) to DNA in vitro and the suppression of oxidative burst in 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated human polymorphonuclear neutrophils (PMNs). 32P-postlabeling analysis of DNA incubated with DMBA in the presence of 3-methylcholanthrene (3-MC)-induced microsomes produced three major adducts derived from anti-, syn- and anti-dihydrodiol epoxides through reactions with dGuo and dAdo, respectively. Phenolic compounds at the concentration of 150 microM reduced the levels of all DMBA-DNA adducts by 55-98%. The most dramatic effect was observed in case of tannic acid, which completely inhibited the formation of DMBA-dAdo adducts. Chlorogenic acid was the least effective inhibitor of DMBA-DNA adducts formation particularly syn-DMBADE-dAdo (20%). Human neutrophils showed a significant dose-related decrease of TPA-induced chemiluminescence after pretreatment with phenolic compounds. The most effective inhibitors were tannic acid and resveratrol with IC(50)=5.19 and 5.76 microM, respectively. These results suggest that the suppression of reactive oxygen species (ROS) and carcinogen-DNA adducts formation may be important for anticarcinogenic activity of the examined phenolics.
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Affiliation(s)
- Ewa Ignatowicz
- Department of Pharmaceutical Biochemistry, Karol Marcinkowski University of Medical Sciences, Grunwaldzka 6, Poznan 60-780, Poland
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Moody JD, Fu PP, Freeman JP, Cerniglia CE. Regio- and stereoselective metabolism of 7,12-dimethylbenz[a]anthracene by Mycobacterium vanbaalenii PYR-1. Appl Environ Microbiol 2003; 69:3924-31. [PMID: 12839762 PMCID: PMC165122 DOI: 10.1128/aem.69.7.3924-3931.2003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The degradation of 7,12-dimethylbenz[a]anthracene (DMBA), a carcinogenic polycyclic aromatic hydrocarbon, by cultures of Mycobacterium vanbaalenii PYR-1 was studied. When M. vanbaalenii PYR-1 was grown in the presence of DMBA for 136 h, high-pressure liquid chromatography (HPLC) analysis showed the presence of four ethyl acetate-extractable compounds and unutilized substrate. Characterization of the metabolites by mass and nuclear magnetic resonance spectrometry indicated initial attack at the C-5 and C-6 positions and on the methyl group attached to C-7 of DMBA. The metabolites were identified as cis-5,6-dihydro-5,6-dihydroxy-7,12-dimethylbenz[a]anthracene (DMBA cis-5,6-dihydrodiol), trans-5,6-dihydro-5,6-dihydroxy-7,12-dimethylbenz[a]anthracene (DMBA trans-5,6-dihydrodiol), and 7-hydroxymethyl-12-methylbenz[a]anthracene, suggesting dioxygenation and monooxygenation reactions. Chiral stationary-phase HPLC analysis of the dihydrodiols showed that DMBA cis-5,6-dihydrodiol had 95% 5S,6R and 5% 5R,6S absolute stereochemistry. On the other hand, the DMBA trans-5,6-dihydrodiol was a 100% 5S,6S enantiomer. A minor photooxidation product, 7,12-epidioxy-7,12-dimethylbenz[a]anthracene, was also formed. The results demonstrate that M. vanbaalenii PYR-1 is highly regio- and stereoselective in the degradation of DMBA.
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Affiliation(s)
- Joanna D Moody
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
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Kleiner HE, Vulimiri SV, Reed MJ, Uberecken A, DiGiovanni J. Role of cytochrome P450 1a1 and 1b1 in the metabolic activation of 7,12-dimethylbenz[a]anthracene and the effects of naturally occurring furanocoumarins on skin tumor initiation. Chem Res Toxicol 2002; 15:226-35. [PMID: 11849049 DOI: 10.1021/tx010151v] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The current study was designed to determine the mechanistic basis for differences in the effects of naturally occurring furanocoumarins on skin tumor initiation by 7,12-dimethylbenz[a]anthracene (DMBA). Female SENCAR mice were pretreated topically with bergamottin, imperatorin, or isopimpinellin (100-3200 nmol), 7,8-benzoflavone (7,8-BF, 5-40 nmol, a known inhibitor of DMBA skin carcinogenesis in mice), or acetone (vehicle control) 5 min prior to topical treatment with DMBA (10 nmol). Imperatorin, isopimpinellin, and 7,8-BF, but not bergamottin, significantly blocked total DMBA-DNA adduct formation. HPLC analysis of DNA adducts revealed that bergamottin preferentially inhibited formation of anti-DMBA diol-epoxide (DMBADE) derived DNA adducts, imperatorin, and isopimpinellin inhibited both anti- and syn- derived adducts, whereas 7,8-BF showed some selectivity for reduction of syn-DMBADE-DNA adducts. Mouse embryo fibroblast C3H/10T1/2 (10T1/2) cells, and mouse hepatoma-derived 1c1c7 (Hepa-1) cells, which preferentially express P450 1b1 and P450 1a1, respectively, were co-incubated with 2 microM bergamottin, imperatorin, isopimpinellin, and 7,8-BF, and with DMBA (2 microM). Hepa-1 cells (P450 1a1) formed mainly anti-DMBADE-DNA adducts. In contrast, 10T1/2 cells (P450 1b1) formed mainly syn-DMBADE-DNA adducts. Bergamottin inhibited DMBA metabolism to DMBA-3,4-diol and blocked DNA adduct formation in Hepa-1 cells, but had little effect in 10T1/2 cells. In contrast, 7,8-BF completely blocked DMBA metabolism and DNA adduct formation in 10T1/2 cells, but had little effect in Hepa-1 cells. Imperatorin and isopimpinellin inhibited DMBA bioactivation in both cell lines. These results indicate that bergamottin is a more selective inhibitor of P450 1a1 and overall a less effective inhibitor of the metabolic activation of DMBA in mouse epidermis. In contrast, imperatorin, isopimpinellin, and especially 7,8-BF, which block metabolic activation of DMBA in mouse epidermis, appear more selective for P450 1b1. On the basis of our studies using 10T1/2 cells and Hepa-1 cells, it appears that P450 1a1 is primarily responsible for converting DMBA-3,4-diol to anti-DMBADE, whereas P450 1b1 is primarily responsible for converting DMBA-3,4-diol to syn-DMBADE. These data demonstrate the role of P450 1a1 and 1b1 in the metabolic activation of DMBA in mouse epidermis and provide a mechanistic explanation for the differential effects of naturally occurring furanocoumarins (and 7,8-BF) on polycyclic aromatic hydrocarbon skin carcinogenesis.
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Affiliation(s)
- Heather E Kleiner
- University of Texas MD Anderson Cancer Center, Science Park-Research Division, Department of Carcinogenesis, P.O. Box 389, Smithville, Texas 78957, USA
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Todorovic R, Ariese F, Devanesan P, Jankowiak R, Small GJ, Rogan E, Cavalieri E. Determination of benzo[a]pyrene- and 7,12-dimethylbenz[a]anthracene-DNA adducts formed in rat mammary glands. Chem Res Toxicol 1997; 10:941-7. [PMID: 9305574 DOI: 10.1021/tx970003y] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Both 7,12-dimethylbenz[a]anthracene (DMBA) and benzo[a]pyrene (BP) are carcinogenic in the rat mammary gland. The depurinating and stable adducts of DMBA and BP formed in vitro and in mouse skin were previously identified and quantitated. Identification and quantitation of the depurinating and stable DNA adducts of DMBA and identification of the depurinating adducts of BP formed in rat mammary glands in the 24 h after intramammillary injection of DMBA or BP are reported in this paper. The depurinating adducts of DMBA, which constitute 52% of all adducts detected, are DMBA bound at the 12-methyl group to the N-7 of adenine (Ade) or guanine (Gua), namely, 7-methylbenz[a]anthracene (MBA)-12-CH2-N7Ade (39%) and 7-MBA-12-CH2-N7Gua (13%). All of the stable adducts were formed from the diol epoxide(s) of DMBA. Depurinating adducts of BP with guanine, namely, 8-(BP-6-yl)-guanine (BP-6-C8Gua) and BP-6-N7Gua, were identified in rat mammary glands treated with BP. The major stable adduct, formed via the diol epoxide pathway, BP-diol epoxide-10-N2dG, accounted for over 64% of all the stable adducts. Three other BP-DNA stable adducts remain unidentified. Thus, rat mammary cells form depurinating adducts of DMBA and BP predominantly via their radical cations and stable adducts via the diol epoxides.
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Affiliation(s)
- R Todorovic
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha 68198-6805, USA
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Chakravarti D, Pelling JC, Cavalieri EL, Rogan EG. Relating aromatic hydrocarbon-induced DNA adducts and c-H-ras mutations in mouse skin papillomas: the role of apurinic sites. Proc Natl Acad Sci U S A 1995; 92:10422-6. [PMID: 7479797 PMCID: PMC40809 DOI: 10.1073/pnas.92.22.10422] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Mouse skin tumors contain activated c-H-ras oncogenes, often caused by point mutations at codons 12 and 13 in exon 1 and codons 59 and 61 in exon 2. Mutagenesis by the noncoding apurinic sites can produce G-->T and A-->T transversions by DNA misreplication with more frequent insertion of deoxyadenosine opposite the apurinic site. Papillomas were induced in mouse skin by several aromatic hydrocarbons, and mutations in the c-H-ras gene were determined to elucidate the relationship among DNA adducts, apurinic sites, and ras oncogene mutations. Dibenzo[a,l]pyrene (DB[a,l]P), DB[a,l]P-11,12-dihydrodiol, anti-DB[a,l]P-11,12-diol-13,14-epoxide, DB[a,l]P-8,9-dihydrodiol, 7,12-dimethylbenz[a]anthracene (DMBA), and 1,2,3,4-tetrahydro-DMBA consistently induced a CAA-->CTA mutation in codon 61 of the c-H-ras oncogene. Benzo[a]pyrene induced a GGC-->GTC mutation in codon 13 in 54% of tumors and a CAA-->CTA mutation in codon 61 in 15%. The pattern of mutations induced by each hydrocarbon correlated with its profile of DNA adducts. For example, both DB[a,l]P and DMBA primarily form DNA adducts at the N-3 and/or N-7 of deoxyadenosine that are lost from the DNA by depurination, generating apurinic sites. Thus, these results support the hypothesis that misreplication of unrepaired apurinic sites generated by loss of hydrocarbon-DNA adducts is responsible for transforming mutations leading to papillomas in mouse skin.
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Affiliation(s)
- D Chakravarti
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha 68198-6805, USA
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Gorelick NJ, Andrews JL, Gu M, Glickman BW. Mutational spectra in the lacl gene in skin from 7,12-dimethylbenz[a]anthracene-treated and untreated transgenic mice. Mol Carcinog 1995; 14:53-62. [PMID: 7546225 DOI: 10.1002/mc.2940140110] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Transgenic mice carrying the bacterial lacl gene in a lambda shuttle vector were used to isolate and characterize background and 7,12-dimethylbenz[a]anthracene (DMBA)-induced mutations in skin. Adult male mice were treated once topically with either DMBA or acetone or were left untreated. Seven days later, DMBA treatment had significantly increased the mutant frequency in the skin (mean +/- SEM, 36 +/- 3 x 10(-5)) versus in vehicle-treated (6.4 +/- 1.2 x 10(-5)) and untreated mice (7.1 x 1.0 x 10(-5)). At least 10 mutants from each of three DMBA-treated and three untreated mice were selected for DNA sequence analysis. In each case, the entire 1080-bp target gene was sequenced. Base-pair substitutions predominated (86 of 96 mutations), although frameshift and deletion mutations were also detected. Twelve percent of the mutants carried more than one mutation. In controls, the mutations were predominantly GC-->AT transitions (26 of 42), and no AT-->TA transversions were recovered. In contrast, in the DMBA-treated mice, AT-->TA transversions represented 42% of the mutations (23 of 54) and GC-->AT transitions accounted for only 11%. The AT-->TA transversions occurred mostly at 5'-CA sites. This class of mutation has been recovered frequently in ras genes from DMBA-treated mice and probably represents an early event in carcinogenesis (Nelson MA et al., Proc Natl Acad Sci USA 89:6398-6402, 1992). Our present results are consistent with the types of DNA damage induced by DMBA. The observation of different mutant frequencies and spectra in treated and control mice demonstrates the utility of this approach in the study of mutagenesis in vivo.
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Affiliation(s)
- N J Gorelick
- Procter & Gamble Company, Miami Valley Laboratories, Cincinnati, OH 45253-8707, USA
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Dipple A, Peltonen K, Cheng SC, Ross H, Bigger CA. Chemical and mutagenic specificities of polycyclic aromatic hydrocarbon carcinogens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1994; 354:101-12. [PMID: 8067279 DOI: 10.1007/978-1-4899-0939-8_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- A Dipple
- Chemistry of Carcinogenesis Laboratory, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, MD 21702
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