1
|
Khan MKA, Akhtar S, Arif JM. Development of In Silico Protocols to Predict Structural Insights into the Metabolic Activation Pathways of Xenobiotics. Interdiscip Sci 2017; 10:329-345. [PMID: 28527150 DOI: 10.1007/s12539-017-0237-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 05/05/2017] [Accepted: 05/09/2017] [Indexed: 11/26/2022]
Abstract
To establish in silico model to predict the structural insight into the metabolic bioactivation pathway of xenobiotics, we considered two specific and one non-specific mammary procarcinogen [e.g., dibenzo[a,l]pyrene (DBP), 7,12-dimethylbenz[a]anthracene (DMBA), and benzo[a]pyrene (BP)]. The CYP1A1, 1B1, 2C9, 1A2 and 2B6 reported in wet-lab studies to actively metabolize DBP also showed strong binding energies (kcal/mol) of -11.50, -10.67, -10.37, -9.76 and -9.72, respectively, with inhibition constants ranging between 0.01 and 0.08 µM. The CYP3A4 depicted minimum binding energy (-9.51 kcal/mol) which is in agreement with the wet-lab reports. Further, relatively better affinity of CYP1A1 and CYP1B1 with the dibenzo[a,l]pyrene-11,12-diol (DBPD) might be indicative of their involvement in carcinogenicity of parent compound. Like DBP, BP (-10.13 kcal/mol, Ki: 0.04 µM) and BP-diols (BPD) (-9.01 kcal/mol, Ki: 0.25 µM) observed plausible binding with CYP1A1 supporting to the reported data that emphasize the major contribution of CYP1A1 in the activation of similar procarcinogens and mutagens. Likewise, in silico results further highlighted the CYP1A1 as key player in bioactivation of DMBA to its carcinogenic metabolites. In case of PhIP metabolism, strong binding interaction predicted with CYP1A1 (-9.63 kcal/mol) rather than CYP1A2 (-8.84 kcal/mol). Dissimilarity in the binding affinity of PhIP might be due to its basic scaffold. Further, molecular dynamics (MD) simulation of 10 ns has been revealed that docked complexes of CYP1A1 with DBP, DMBA and BP are comparatively more stable than the complex of PhIP. Moreover, the current findings might be valuable as reference model in prediction and elucidation of the approximate metabolic pathway of xenobiotics.
Collapse
Affiliation(s)
- M Kalim A Khan
- Department of Bioengineering, Faculty of Engineering, Integral University, Lucknow, 226026, India
| | - Salman Akhtar
- Department of Bioengineering, Faculty of Engineering, Integral University, Lucknow, 226026, India
| | - Jamal M Arif
- Department of Biosciences, Faculty of Applied Sciences, Integral University, Kursi Road, P.O. Box Basha, Lucknow, 226026, India.
| |
Collapse
|
2
|
Fukuda I, Nishiumi S, Mukai R, Yoshida KI, Ashida H. Catechins in tea suppress the activity of cytochrome P450 1A1 through the aryl hydrocarbon receptor activation pathway in rat livers. Int J Food Sci Nutr 2015; 66:300-7. [PMID: 25582180 DOI: 10.3109/09637486.2014.992007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons (HAHs) develop various adverse effects through activation of an aryl hydrocarbon receptor (AhR). The suppressive effects of brewed green tea and black tea on 3-methylcholanthrene (MC)-induced AhR activation and its downstream events were examined in the liver of rats. Ad-libitum drinking of green tea and black tea suppressed MC-induced AhR activation and elevation of ethoxyresorufin O-deethylase activity in the liver, whereas the teas themselves did not induce them. Tea showed a suppressive fashion on the expression of cytochrome P450 1A1 (CYP1A1). Tea suppressed the AhR activation induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) ex vivo. A part of catechins and theaflavins was present in plasma and liver as conjugated and intact forms. The results of this study suggested that active component(s) of tea are incorporated in the liver and suppress the activity of CYP1As through the AhR activation pathway.
Collapse
Affiliation(s)
- Itsuko Fukuda
- Research Center for Food Safety and Security, Graduate School of Agricultural Science, Kobe University , Hyogo , Japan and
| | | | | | | | | |
Collapse
|
3
|
Zhang SM, Chen KM, Sun YW, Aliaga C, Lin JM, Sharma AK, Amin S, El-Bayoumy K. Simultaneous detection of deoxyadenosine and deoxyguanosine adducts in the tongue and other oral tissues of mice treated with Dibenzo[a,l]pyrene. Chem Res Toxicol 2014; 27:1199-206. [PMID: 24911113 PMCID: PMC4106691 DOI: 10.1021/tx5001078] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
We
were the first to demonstrate that direct application of the
environmental pollutant and tobacco smoke constituent dibenzo[a,l]pyrene (DB[a,l]P) into the oral cavity of mice induced squamous cell
carcinoma (SCC) in oral tissues but not in the tongue; however, the
mechanisms that can account for the varied carcinogenicity remain
to be determined. Furthermore, we also showed that not only dA adducts,
but also dG adducts can account for the mutagenic activity of DB[a,l]P in the oral tissues in vivo. In this study, we initially focused on DB[a,l]P-induced genotoxic effects in both oral and tongue tissues.
Therefore, to fully assess the contribution of these DNA adducts in
the initiation stage of carcinogenesis induced by DB[a,l]P, an LC-MS/MS method to simultaneously detect
and quantify DB[a,l]PDE-dG and -dA
adducts was developed. Mice were orally administered with DB[a,l]P (24 nmole, 3 times per week for 5
weeks) or its fjord region diol epoxide, (±)-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]pyrene (DB[a,l]PDE, 12 nmole, single application); animals were sacrificed
at 2, 7, 14, and 28 days after the last dose of carcinogen administration.
Oral and tongue tissues were obtained and DNA were isolated followed
by enzymatic hydrolysis. Following the development of an isotope dilution
LC-MS/MS method, we successfully detected (−)-anti-cis- and (−)-anti-trans-DB[a,l]PDE-N2-dG, as well as (−)-anti-cis- and (−)-anti-trans-DB[a,l]PDE-N6-dA in oral and tongue
tissues of mice treated with DB[a,l]P. Levels of (−)-anti-trans-DB[a,l]PDE-N6-dA were
≥2 folds higher than (−)-anti-cis-DB[a,l]PDE-N6-dA adduct and those of dG adducts in the oral tissues and tongue
at all time points selected after the cessation of DB[a,l]P treatment. Levels of dG adducts were comparable
in both tissues. Collectively, our results support that DB[a,l]P is predominantly metabolized to (−)-anti-DB[a,l]PDE, and the
levels and persistence of (−)-anti-trans-DB[a,l]PDE-N6-dA may, in part, explain the carcinogenicity of DB[a,l]P in the oral tissues but not in the
tongue.
Collapse
Affiliation(s)
- Shang-Min Zhang
- Dept. of Biochemistry and Molecular Biology, Penn State College of Medicine , Hershey, Pennsylvania 17033, United States
| | | | | | | | | | | | | | | |
Collapse
|
4
|
Pan S, Li D, Zhao L, Schenkman JB, Rusling JF. Genotoxicity-related chemistry of human metabolites of benzo[ghi]perylene (B[ghi]P) investigated using electro-optical arrays and DNA/microsome biocolloid reactors with LC-MS/MS. Chem Res Toxicol 2013; 26:1229-39. [PMID: 23879290 PMCID: PMC3763812 DOI: 10.1021/tx400147c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is limited and sometimes contradictory information about the genotoxicity of the polycyclic aromatic hydrocarbon benzo[ghi]perylene (B[ghi]P). Using recently developed metabolic toxicity screening arrays and a biocolloid reactor-LC-MS/MS approach, both featuring films of DNA and human metabolic enzymes, we demonstrated the relatively low reactivity of metabolically activated B[ghi]P toward DNA. Electro-optical toxicity screening arrays showed that B[ghi]P metabolites damage DNA at a 3-fold lower rate than benzo[a]pyrene (B[a]P), whose metabolites have a strong and well-understood propensity for DNA damage. Metabolic studies using magnetic bead biocolloid reactors coated with microsomal enzymes in 96-well plates showed that cyt P450s 1A1 and 1B1 provide high activity for B[ghi]P and B[a]P conversion. Consistent with published results, the major metabolism of B[ghi]P involved oxidations at 3,4 and 11,12 positions, leading to the formation of B[ghi]P 3,4-oxide and B[ghi]P 3,4,11,12-bisoxide. B[ghi]P 3,4-oxide was synthesized and reacted with deoxyadenosine at N6 and N7 positions and with deoxyguanosine at the N2 position. B[ghi]P 3,4-oxide is hydrolytically unstable and transforms into the 3,4-diol or converts to 3- or 4-hydroxy B[ghi]P. LC-MS/MS of reaction products from the magnetic biocolloid reactor particles coated with DNA and human enzymes revealed for the first time that a major DNA adduct results from the reaction between B[ghi]P 3,4,11,12-bisoxide and deoxyguanosine. Results also demonstrated 5-fold lower formation rates of the major DNA adduct for B[ghi]P metabolites compared to B[a]P. Overall, results from both the electro-optical array and biocolloid reactor-LC-MS/MS consistently suggest a lower human genotoxicity profile of B[ghi]P than B[a]P.
Collapse
Affiliation(s)
- Shenmin Pan
- Department of Chemistry, University of Connecticut, Storrs, CT 06269
| | - Dandan Li
- Department of Chemistry, University of Connecticut, Storrs, CT 06269
| | - Linlin Zhao
- Department of Chemistry, University of Connecticut, Storrs, CT 06269
| | - John B. Schenkman
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06032
| | - James F. Rusling
- Department of Chemistry, University of Connecticut, Storrs, CT 06269
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06032
| |
Collapse
|
5
|
Kropachev K, Kolbanovskiy M, Liu Z, Cai Y, Zhang L, Schwaid AG, Kolbanovskiy A, Ding S, Amin S, Broyde S, Geacintov NE. Adenine-DNA adducts derived from the highly tumorigenic Dibenzo[a,l]pyrene are resistant to nucleotide excision repair while guanine adducts are not. Chem Res Toxicol 2013; 26:783-93. [PMID: 23570232 DOI: 10.1021/tx400080k] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The structural origins of differences in susceptibilities of various DNA lesions to nucleotide excision repair (NER) are poorly understood. Here we compared, in the same sequence context, the relative NER dual incision efficiencies elicited by two stereochemically distinct pairs of guanine (N(2)-dG) and adenine (N(6)-dA) DNA lesions, derived from enantiomeric genotoxic diol epoxides of the highly tumorigenic fjord region polycyclic aromatic hydrocarbon dibenzo[a,l]pyrene (DB[a,l]P). Remarkably, in cell-free HeLa cell extracts, the guanine adduct with R absolute chemistry at the N(2)-dG linkage site is ∼35 times more susceptible to NER dual incisions than the stereochemically identical N(6)-dA adduct. For the guanine and adenine adducts with S stereochemistry, a similar but somewhat smaller effect (factor of ∼15) is observed. The striking resistance of the bulky N(6)-dA in contrast to the modest to good susceptibilities of the N(2)-dG adducts to NER is interpreted in terms of the balance between lesion-induced DNA distorting and DNA stabilizing van der Waals interactions in their structures, that are partly reflected in the overall thermal stabilities of the modified duplexes. Our results are consistent with the hypothesis that the high genotoxic activity of DB[a,l]P is related to the formation of NER-resistant and persistent DB[a,l]P-derived adenine adducts in cellular DNA.
Collapse
Affiliation(s)
- Konstantin Kropachev
- Department of Chemistry, New York University , New York, New York 10003, United States
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Lin Y, Yao Y, Liu S, Wang L, Moorthy B, Xiong D, Cheng T, Ding X, Gu J. Role of mammary epithelial and stromal P450 enzymes in the clearance and metabolic activation of 7,12-dimethylbenz(a)anthracene in mice. Toxicol Lett 2012; 212:97-105. [PMID: 22595614 DOI: 10.1016/j.toxlet.2012.05.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/03/2012] [Accepted: 05/05/2012] [Indexed: 11/17/2022]
Abstract
Microsomal cytochrome P450 (P450) enzymes, which are important in the metabolism of carcinogens, are expressed in both epithelial and stromal cells in the mammary gland. The aim of this study was to investigate the roles of mammary epithelial P450 enzymes in the bioactivation and disposition of 7,12-dimethylbenz(a)anthracene (DMBA), a breast carcinogen, in the mammary gland. A new mouse model (named MEpi-Cpr-null) was produced, wherein P450 activities in the mammary epithelial cells are suppressed through tissue-specific deletion of the gene for P450 reductase (Cpr), an enzyme required for the activities of all microsomal P450 enzymes. Comparisons between wild-type and MEpi-Cpr-null mice showed that the tissue-specific deletion of Cpr in the mammary epithelial cells was accompanied by significant increases in the levels of DMBA and DMBA-DNA adduct in the mammary gland following a single intraperitoneal injection of DMBA at 50mg/kg. Immunohistochemical and immunoblot analysis further revealed greater induction of CYP1B1 expression by the DMBA treatment in the mammary stroma of the MEpi-Cpr-null mice than in that of the WT mice. These findings not only demonstrate that the epithelial P450 enzymes play important roles in the clearance of DMBA, but also suggest that P450 enzymes in both mammary epithelial and stromal cells contribute to carcinogen-mediated DNA damage.
Collapse
Affiliation(s)
- Yang Lin
- Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Chen KM, Zhang SM, Aliaga C, Sun YW, Cooper T, Gowdahalli K, Zhu J, Amin S, El-Bayoumy K. Induction of ovarian cancer and DNA adducts by Dibenzo[a,l]pyrene in the mouse. Chem Res Toxicol 2012; 25:374-80. [PMID: 22107356 DOI: 10.1021/tx2004322] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tobacco smoking is an etiological factor of ovarian cacner; however, the mechanisms remain largely undefined. Therefore, as an initial investigation, we examined the carcinogenicity and DNA adducts formation in the ovary of mice treated with DB[a,l]P, a tobacco smoke constituent and environmental pollutant. Ovarian tumors in B6C3F1 mice were induced by direct application of DB[a,l]P (24, 12, 6, and 3 nmol/mouse, three times a week for 38 weeks) into the oral cavity of mice. At 6 nmol, DB[a,l]P induced the highest total ovarian tumor incidence (79%), but the incidence of malignancy was only 15%. However, at the dose of 12 nmol, the total ovarian tumor incidence was 75%, and the incidence of malignancy was 65%. In addition to ovarian tumors, at the dose of 24 nmol, DB[a,l]P induced lesions in sites distal from the ovaries including the skin, mammary, lung, and oral tissues, which were rare at doses lower than 24 nmol. Another bioassay was conducted to detect and quantify DNA adducts induced by DB[a,l]P (24 nmol, three times a week for 5 weeks) in the ovary at 48 h and 1, 2, and 4 weeks after the last administration of DB[a,l]P. DNA was isolated, and the dibenzo[a,l]pyrene-11,12-dihydrodiol-13,14-epoxide (DB[a,l]PDE)-DNA adducts were analyzed by a LC-MS/MS method. DB[a,l]P resulted in the formation of (-)-anti-cis-DB[a,l]PDE-dA and (-)-anti-trans-DB[a,l]PDE-dA adducts, which were 0.8 and 1.6 fmol/10(6) dA, respectively, in ovaries of mice within 48 h, and the level of adducts decreased over a week. Our results indicated that DB[a,l]P can be metabolized to form (-)-anti-DB[a,l]PDE; the latter may, in part, account for DB[a,l]P-induced ovarian cancer. This animal model should assist to better understand the mechanisms, account for the induction of ovarian cancer by tobacco carcinogens, and facilitate the development of chemopreventive agents against ovarian cancer.
Collapse
Affiliation(s)
- Kun-Ming Chen
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine , Hershey, Pennsylvania 17033, United States.
| | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Spencer WA, Singh J, Orren DK. Formation and differential repair of covalent DNA adducts generated by treatment of human cells with (+/-)-anti-dibenzo[a,l]pyrene-11,12-diol-13,14-epoxide. Chem Res Toxicol 2009; 22:81-9. [PMID: 19053321 DOI: 10.1021/tx8001675] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Dibenzo[a,l]pyrene (DBP) is the most potent tumor initiating polycyclic aromatic hydrocarbon tested to date in rodent tumor models. To investigate how DBP adduct formation and removal might influence carcinogenesis, we have examined the effects of treatment of several nucleotide excision repair (NER)-proficient (NER(+)) and -deficient (NER(-)) cell lines with the carcinogenic metabolite (+/-)-anti-DBP-11,12-diol-13,14-epoxide (DBPDE). The treatment of NER(-) cells with (+/-)-anti-DBPDE for 0.5, 1, or 2 h yielded similar total adduct levels, indicating that adduct formation was essentially complete during a 2 h treatment period with no additional adducts produced after replacement of media. In all cell lines, treatment with (+/-)-anti-DBPDE generated five major and at least two minor adducts that were chromatographically identical to those formed by direct treatment of 3'-GMP and 3'-AMP with (+/-)-anti-DBPDE. When adduct levels were assessed in NER(-) cells, the number of adducts/10(9) nucleotides decreased over time, suggesting that DNA replication was ongoing, so we incorporated a normalization strategy based on DNA synthesis. This strategy indicated that DBPDE-DNA adduct levels in NER(-) cells are stable over time. After normalization for DNA synthesis in the NER(+) cells, our data indicated that three adducts showed biphasic repair kinetics. A faster rate of removal was observed during the first 6 h following DBPDE removal followed by a slower rate for up to 34 h. Importantly, two of the major guanine adducts were particularly refractory to removal in the NER(+) cells. Our results suggest that the extreme carcinogenicity of DBPDE may result from the ability of a substantial percentage of two structurally distinct DBPDE-DNA adducts to escape repair.
Collapse
Affiliation(s)
- Wendy A Spencer
- Graduate Center for Toxicology, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
| | | | | |
Collapse
|
9
|
Abstract
Cancer is as a highly complex and multifactorial disease responsible for the death of hundreds of thousands of people in the western countries every year. Since cancer is clonal and due to changes at the level of the genetic material, viruses, chemical mutagens and other exogenous factors such as short-waved electromagnetic radiation that alter the structure of DNA are among the principal causes. The focus of this present review lies on the influence of the molecular structure of two well-investigated chemical carcinogens from the group of polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP). Although there is only one additional benzo ring present in the latter compound, DBP exerts much stronger genotoxic and carcinogenic effects in certain tumor models as compared to BP. Actually, DBP has been identified as the most potent tumorigen among all carcinogenic PAHs tested to date. The genotoxic effects of both compounds investigated in mammalian cells in culture or in animal models are described. Comparison of enzymatic activation, DNA binding levels of reactive diol-epoxide metabolites, efficiency of DNA adduct repair and mutagenicity provides some clues on why this compound is about 100-fold more potent in inducing tumors than BP. The data published during the past 20 years support and strengthen the idea that compound-inherent physicochemical parameters, along with inefficient repair of certain kinds of DNA lesions formed upon metabolic activation, can be considered as strong determinants for high carcinogenic potency of a chemical.
Collapse
|
10
|
Ravoori S, Ayotte P, Srinivasan C, Pereg D, Robertson LW, Russell GK, Jeyabalan J, Gupta RC. DNA damage associated with PCBs in the whole blood cells of Inuit. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:273-276. [PMID: 21783863 DOI: 10.1016/j.etap.2007.10.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lower chlorinated PCBs can damage DNA directly or via free radical mechanisms. In order to assess the DNA-damaging potential of PCBs in humans, blood samples were collected from Inuit population from Salluit, Northern Canada. Their diet comprises blubber from sea mammals and fatty fish, which accumulate non-biodegradable PCBs at varying levels. The 103 samples thus collected were categorized into low-, medium- and high-PCB exposure groups. A comprehensive (32)P-postlabeling adductomics technology, which allows measure differences in DNA adduct profiles of polar and lipophilic adducts between control and exposure groups, was applied to these samples to assess the effect of PCB on DNA damage. The adduct patterns obtained were qualitatively similar to other human tissues studied previously. A range of highly polar to lipophilic subgroups of adducts were detected. The known oxidative lesion, 8-oxodG was predominant. While some individual adducts appear to accumulate with increasing PCB levels, a definitive association could not be made. A possible confounder effect of selenium is discussed.
Collapse
Affiliation(s)
- Srivani Ravoori
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Mahadevan B, Luch A, Atkin J, Haynes M, Nguyen T, Baird WM. Inhibition of human cytochrome p450 1b1 further clarifies its role in the activation of dibenzo[a,l]pyrene in cells in culture. J Biochem Mol Toxicol 2007; 21:101-9. [PMID: 17623886 DOI: 10.1002/jbt.20168] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Metabolic activation and DNA adduct formation of the carcinogenic aromatic hydrocarbon dibenzo[a,l]pyrene (DBP) was investigated in human mammary carcinoma MCF-7 cells and human cytochrome P450 (CYP) 1B1-expressing Chinese hamster V79 cells in culture. It has been shown that DBP is metabolically activated to DNA-binding diol epoxides both in vitro and in vivo. To further establish the role of human CYP1B1 in the activation of DBP, both cell lines were cotreated with DBP and a selective chemical inhibitor of CYP1B1, 2,4,3' ,5'-tetramethoxy-stilbene (TMS). Results from DBP-DNA adduct analyses revealed the complete inhibition of DNA binding when cells were cotreated with DBP and TMS in comparison to DBP alone. Inactivation of CYP1B1 by TMS was also demonstrated through a decrease in the 7-ethoxyresorufin O-deethylase (EROD) activity in microsomes isolated from these cells. Emodin, 3-methyl-1,6,8-trihydroxyanthraquinone, an active ingredient of an herb, has been recently shown of being able to induce CYP1 gene expression. Examination of human CYP1B1 induction and EROD activity confirmed an increase in protein levels upon cotreatment with emodin and DBP. Despite increases in protein levels and enzyme activity, there was no significant change in DBP-DNA binding levels at very low substrate concentrations (17 nM). The data obtained in this study emphasize the central role of CYP1B1 in the activation of DBP in human cells in culture.
Collapse
Affiliation(s)
- Brinda Mahadevan
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA.
| | | | | | | | | | | |
Collapse
|
12
|
Okona-Mensah KB, Battershill J, Boobis A, Fielder R. An approach to investigating the importance of high potency polycyclic aromatic hydrocarbons (PAHs) in the induction of lung cancer by air pollution. Food Chem Toxicol 2005; 43:1103-16. [PMID: 15833386 DOI: 10.1016/j.fct.2005.03.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 02/09/2005] [Accepted: 03/01/2005] [Indexed: 10/25/2022]
Abstract
Evidence suggests that people living in urban areas have an increased risk of lung cancer due to higher levels of air pollution in these areas. Benzo[a]pyrene (B[a]P) is currently used as the main indicator of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in air pollution, but there is concern that B[a]P may not be the ideal surrogate of choice for PAH mixtures since higher potency PAHs have recently been identified which could potentially contribute more and variably to the overall carcinogenicity. Dibenzo[a,h]anthracene (DBA) and dibenzo[a,l]pyrene (DB[a,l]P) are estimated to have carcinogenic potencies 10 or more times greater than B[a]P but data on their presence and formation in the environment are limited. Several occupational and environmental PAH biomonitoring studies are reviewed here, with particular focus on the specific exposure groups, study design, sample tissue, in particular the use of nasal tissues, and biomarkers used in each study. Consideration of these data is then used to propose a novel biomonitoring approach to evaluate exposure, uptake and the role of high potency PAHs in air pollution-related lung cancer. This is based upon an occupational study examining specific DNA adducts for DBA and DB[a,l]P in nasal cells to evaluate the extent to which these high potency PAHs might contribute to the increased risk of developing lung cancer from air pollution.
Collapse
Affiliation(s)
- K B Okona-Mensah
- Department of Health Toxicology Unit, Section of Experimental Medicine and Toxicology, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK.
| | | | | | | |
Collapse
|
13
|
Stewart SL, Querec TD, Ochman AR, Gruver BN, Bao R, Babb JS, Wong TS, Koutroukides T, Pinnola AD, Klein-Szanto A, Hamilton TC, Patriotis C. Characterization of a Carcinogenesis Rat Model of Ovarian Preneoplasia and Neoplasia. Cancer Res 2004; 64:8177-83. [PMID: 15548682 DOI: 10.1158/0008-5472.can-04-1702] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Animal models of ovarian cancer are crucial for understanding the pathogenesis of the disease and for testing new treatment strategies. A model of ovarian carcinogenesis in the rat was modified and improved to yield ovarian preneoplastic and neoplastic lesions that pathogenetically resemble human ovarian cancer. A significantly lower dose (2 to 5 mug per ovary) of 7,12-dimethylbenz(a)anthracene (DMBA) was applied to the one ovary to maximally preserve its structural integrity. DMBA-induced mutagenesis was additionally combined with repetitive gonadotropin hormone stimulation to induce multiple cycles of active proliferation of the ovarian surface epithelium. Animals were treated in three arms of different doses of DMBA alone or followed by hormone administration. Comparison of the DMBA-treated ovaries with the contralateral control organs revealed the presence of epithelial cell origin lesions at morphologically distinct stages of preneoplasia and neoplasia. Their histopathology and path of dissemination to other organs are very similar to human ovarian cancer. Hormone cotreatment led to an increased lesion severity, indicating that gonadotropins may promote ovarian cancer progression. Point mutations in the Tp53 and Ki-Ras genes were detected that are also characteristic of human ovarian carcinomas. Additionally, an overexpression of estrogen and progesterone receptors was observed in preneoplastic and early neoplastic lesions, suggesting a role of these receptors in ovarian cancer development. These data indicate that this DMBA animal model gives rise to ovarian lesions that closely resemble human ovarian cancer and it is adequate for additional studies on the mechanisms of the disease and its clinical management.
Collapse
Affiliation(s)
- Sherri L Stewart
- Medical Science Division, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Arif JM, Al-Hazzani AA, Kunhi M, Al-Khodairy F. Novel Marine Compounds: Anticancer or Genotoxic? J Biomed Biotechnol 2004; 2004:93-98. [PMID: 15240919 PMCID: PMC548801 DOI: 10.1155/s1110724304307060] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In the past several decades, marine organisms have generously gifted to the pharmaceutical industries numerous naturally bioactive compounds with antiviral, antibacterial, antimalarial, anti-inflammatory, antioxidant, and anticancer potentials. But till date only few anticancer drugs (cytarabine, vidarabine) have been commercially developed from marine compounds while several others are currently in different clinical trials. Majority of these compounds were tested in the tumor xenograft models, however, lack of anticancer potential data in the chemical- and/or oncogene-induced pre-initiation animal carcinogenesis models might have cost some of the marine anticancer compounds an early exit from the clinical trials. This review critically discusses importance of preclinical evaluation, failure of human clinical trials with certain potential anticancer agents, the screening tests used, and choice of biomarkers.
Collapse
Affiliation(s)
- Jamal M. Arif
- Biological and Medical Research, King Faisal Specialist Hospital and Research Center,
PO Box 3354, MBC #03, Riyadh 11211, Saudi Arabia
- *Jamal M. Arif:
| | - Amal A. Al-Hazzani
- Biological and Medical Research, King Faisal Specialist Hospital and Research Center,
PO Box 3354, MBC #03, Riyadh 11211, Saudi Arabia
| | - Muhammed Kunhi
- Biological and Medical Research, King Faisal Specialist Hospital and Research Center,
PO Box 3354, MBC #03, Riyadh 11211, Saudi Arabia
| | - Fahad Al-Khodairy
- Biological and Medical Research, King Faisal Specialist Hospital and Research Center,
PO Box 3354, MBC #03, Riyadh 11211, Saudi Arabia
| |
Collapse
|
15
|
Tran HP, Prakash AS, Barnard R, Chiswell B, Ng JC. Arsenic inhibits the repair of DNA damage induced by benzo(a)pyrene. Toxicol Lett 2002; 133:59-67. [PMID: 12076510 DOI: 10.1016/s0378-4274(02)00088-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In order to study the effect of arsenic on DNA damage, Sprague-Dawley rats were dosed with sodium arsenite (10 mg/kg) with or without 800 microg of benzo(a)pyrene (BP) by intramammilary injection. The animals were sacrificed on day 1, 3, 5, 10 and 27 and the mammary gland tissues were collected for DNA adduct measurement using a (32)P post-labeling assay. Animals dosed with arsenic alone did not show any DNA adducts. DNA adduct levels in rats dosed with BP alone reached a maximum level by day 5, reducing to 13% of this level by day 27. Adduct levels in rats dosed with arsenic and BP also reached a maximum by day 5 but only 80% of the level observed in the BP group. However, 84% of this amount still remained by day 27. The First Nucleotide Change (FNC) technique was used for the screening of 115 samples of various tissues from mice that had been chronically exposed to sodium arsenate for over 2 years revealed that inorganic arsenic did not attack the two putative hotspots (codons 131 and 154) of the hOGG1 gene. These results support the hypothesis that arsenic exerts its biological activity through DNA repair inhibition.
Collapse
Affiliation(s)
- Huu-Phuc Tran
- National Research Centre for Environmental Toxicology, 39 Kessels Road, Coopers Plains, Brisbane, Qld 4108 Australia
| | | | | | | | | |
Collapse
|
16
|
Smith WA, Freeman JW, Gupta RC. Effect of chemopreventive agents on DNA adduction induced by the potent mammary carcinogen dibenzo[a,l]pyrene in the human breast cells MCF-7. Mutat Res 2001; 480-481:97-108. [PMID: 11506803 DOI: 10.1016/s0027-5107(01)00173-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Over 1500 structurally diverse chemicals have been identified which have potential cancer chemopreventive properties. The efficacy and mechanisms of this growing list of chemoprotective agents may be studied using short-term bioassays that employ relevant end-points of the carcinogenic process. In this study, we have examined the effects of eight potential chemopreventive agents, N-acetylcysteine (NAC), benzylisocyanate (BIC), chlorophyllin, curcumin, 1,2-dithiole-3-thione (D3T), ellagic acid, genistein, and oltipraz, on DNA adduction of the potent mammary carcinogen dibenzo[a,l]pyrene (DBP) using the human breast cell line MCF-7. Bioactivation of DBP by MCF-7 cells resulted in the formation of one predominant (55%) dA-derived and several other dA- or dG-derived DNA adducts. Three test agents, oltipraz, D3T, and chlorophyllin substantially (>65%) inhibited DBP-DNA adduction at the highest dose tested (30 microM). These agents also significantly inhibited DBP adduct levels at a lower dose of 15 microM, while oltipraz was effective even at the lowest dose of 5 microM. Two other agents, genistein and ellagic acid were moderate (45%) DBP-DNA adduct inhibitors at the highest dose tested, while NAC, curcumin, and BIC were ineffective. These studies indicate that the MCF-7 cell line is an applicable model to study the efficacy of cancer chemopreventive agents in a human setting. Moreover, this model may also provide information regarding the effect of the test agents on carcinogen bioactivation and detoxification enzymes.
Collapse
Affiliation(s)
- W A Smith
- Graduate Center for Toxicology, 354 Health Sciences Research Building, University of Kentucky Medical Center, Lexington, KY 40536-0305, USA
| | | | | |
Collapse
|
17
|
Abstract
Dithiolethiones are currently one of the most promising classes of cancer chemopreventive agents that exhibit antitumorigenic properties at numerous organ sites against several classes of carcinogens. In the current study, we examined the effects of 2 dithiolethiones, 1,2-dithiole-3-thione (D3T) and its structural analogue oltipraz, on DNA adduction induced by the potent mammary carcinogen dibenzo-[a,l]pyrene (DBP) in vivo. Female Sprague-Dawley rats were provided dietary D3T and oltipraz (500 ppm each) for I week followed by a single intragastric dose of DBP (8 micromol/kg body weight) and killed 5 days later. D3T inhibited DBP-DNA adduction from 78% to 82% in all tissues examined, while oltipraz was equally effective in the lung and liver but less effective in the mammary glands, inhibiting DBP-DNA adduction by nearly 60%. These data coupled with their broad anti-tumor specificity support the use of D3T and oltipraz as cancer-preventive agents in clinical trials.
Collapse
Affiliation(s)
- W A Smith
- Graduate Center for Toxicology, University of Kentucky Medical Center, Lexington 40536-0305, USA
| | | | | |
Collapse
|
18
|
van der Bijl P, van Eyk AD. Penetration of benzo[a]pyrene through human buccal and vaginal mucosa. ORAL SURGERY, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS 1999; 87:452-5. [PMID: 10225628 DOI: 10.1016/s1079-2104(99)70245-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE The aim of this study was to compare buccal and vaginal mucosa with respect to their permeability to a potent carcinogen, benzo[a]pyrene. STUDY DESIGN Six clinically healthy vaginal mucosa specimens (mean patient age +/- standard deviation, 52+/-13.4 years; age range, 37-69 years) and 6 buccal mucosa specimens (from 5 male patients and 1 female patient: mean patient age +/- standard deviation, 32+/-5.2 years; age range, 24-39 years) were obtained during surgery. In vitro flux rates of benzo[a]pyrene across specimens were determined through use of a flow-through diffusion apparatus. Analysis of variance, a Duncan multiple range test, and an unpaired t test were used to determine steady state kinetics and flux differences over time intervals. RESULTS No statistically significant differences were observed between the overall mean flux values of benzo[a]pyrene across the 2 kinds of mucosa. CONCLUSIONS The findings further support the hypothesis that human vaginal mucosa can be used as a model for buccal mucosa in studies of permeability to various chemical compounds.
Collapse
Affiliation(s)
- P van der Bijl
- Oral and Dental Research Institute, Faculty of Dentistry, University of Stellenbosch, Tygerberg, South Africa
| | | |
Collapse
|
19
|
Luch A, Friesel H, Seidel A, Platt KL. Tumor-initiating activity of the (+)-(S,S)- and (-)-(R,R)- enantiomers of trans-11,12-dihydroxy-11,12-dihydrodibenzo[a,l]pyrene in mouse skin. Cancer Lett 1999; 136:119-28. [PMID: 10355740 DOI: 10.1016/s0304-3835(98)00265-1] [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
A single administration of enantiomerically pure 11,12-dihydrodiols of dibenzo[a,l]pyrene (DB[a,l]P) on the back of NMRI mice and subsequent chronic treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) (initiation/promotion assay) revealed strikingly different carcinogenic activities of both enantiomers. Tumor-initiating activity of (-)-(11R,12R)-DB[a,l]P-dihydrodiol, which is the metabolic precursor of the (-)-anti-(11R,12S)-dihydrodiol (13S,14R)-epoxide, was exceptionally higher than the corresponding effect of (+)-(11S,12S)-DB[a,l]P-dihydrodiol, the metabolic precursor of (+)-syn-(11S,12R)-dihydrodiol (13S,14R)-epoxide. After topical application of 10 nmol (-)-11,12-dihydrodiol and promotion with TPA twice weekly for a further 18 weeks 93% of treated animals exhibited four to five tumors. In contrast, no neoplasms were observed after treatment with 10 nmol (+)-11,12-dihydrodiol, whereas in the group exposed to 20 nmol of this enantiomer only 13% of mice developed neoplasms (0.1 tumors/survivor). For DB[a,l]P, considered as the most potent carcinogenic polycyclic aromatic hydrocarbon to date, stereoselective formation of (+)-syn- and (-)-anti-11,12-dihydrodiol 13,14-epoxides via the corresponding enantiomeric 11,12-dihydrodiols has been found to be the principal metabolic activation pathway leading to DNA adducts and mutagenicity. Our study demonstrates that the striking difference in carcinogenic activity in mouse skin of (+)-(11S,12S)- and (-)-(11R,12R)-DB[a,l]P-dihydrodiol convincingly reflects the different genotoxicity, i.e. DNA binding and mutagenicity, of both enantiomers observed earlier.
Collapse
Affiliation(s)
- A Luch
- Institute of Toxicology, University of Mainz, Germany
| | | | | | | |
Collapse
|
20
|
Abstract
The 32P-postlabelling assay is widely used for detection of carcinogen-DNA adducts and other types of modified nucleotides in DNA. The principle of the method is the enzymatic digestion of DNA to nucleotides, 5'-labelling of these nucleotides with an isotopically labelled phosphate group, and the resolution and detection of the labelled products. Since the development of the original procedure in the early 1980s, many methods have been developed to increase the sensitivity of the method by selection of the modified nucleotides prior to labelling. In favourable circumstances, the method can achieve a level of detection as low as 1 modification in 10(10) nucleotides and requires relatively small quantities of DNA (less than 10 microg). It has been used to detect and characterise DNA adducts formed by numerous genotoxic carcinogens in bacterial and mammalian cells, in animals and, in some cases, in human tissues. Most classes of carcinogen have been subjected to 32P-postlabelling analysis, ranging from bulky and/or aromatic compounds to small and/or aliphatic compounds; it has also been used, with modifications, to detect apurinic sites in DNA, oxidative damage to DNA, UV-induced photodimers and, to a lesser extent, DNA damage caused by cytotoxic drugs. It has provided the first clear evidence for the DNA-damaging properties of several synthetic carcinogenic hormones. It has revealed the DNA-damaging potential of complex mixtures such as coal-tar and tobacco smoke. It has been used in human biomonitoring studies to detect DNA damage from occupational exposure to carcinogens, and also from environmental (i.e. non-occupational) exposures. It has also led to the discovery of the presence of numerous modifications in DNA arising from endogenous processes. The rapid expansion in the use of the assay has resulted in some divergence of procedures and there is a case to be made for the use of more standardised protocols, particularly where human exposure to carcinogens is being measured and where such results may be required for risk assessment. While the procedure is quantifiable, the efficiency of adduct labelling is, in many cases, not quantitative, and the lack of adduct standards has, in many cases, limited the interpretation of data to a demonstration of higher adduct levels in exposed groups compared with unexposed groups. Future developments are expected in automation, standardisation and, in combination with other analytical methods, elucidation of the structures of the many DNA lesions whose existence has been revealed by the 32P-postlabelling technique.
Collapse
Affiliation(s)
- D H Phillips
- Haddow Laboratories, Institute of Cancer Research, Sutton, UK
| |
Collapse
|