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Abstract
Every year, over 2 million women are diagnosed with breast cancer. Although considerable progress was made within the last years in cancer prevention, diagnosis and treatment, breast cancer is still responsible for over 600,000 of deaths per year. Over the years, numerous mouse models have been developed to understand breast cancer etiology and progression. Among those, mammary carcinomas induced by carcinogen, such as 7,12-dimethylbenz[a]anthracene (DMBA), has been widely used. Generally, 30-70% of mice exposed to 4-6 weekly doses of 1mg of DMBA during the peripubertal period (4-10 weeks of age) will develop mammary tumors within 150-200 days after the first exposure, that sometime metastasize to the lungs. As a result, DMBA-induced tumorigenesis is thought to be an accurate and relevant model to study breast cancer as it closely mimics this multistep process. This chapter presents the typical protocol used in mice to induce mammary gland tumors using DMBA. The influence of the number of doses and the total burden of DMBA given, as well as of the age and strain of the mice on mammary gland incident and on tumor onset are discussed. The current knowledge regarding mechanisms involved in DMBA-induced tumorigenesis is also presented.
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Dragani TA, Sozzi G, Della Porta G. Spontaneous and Urethan-Induced Tumor Incidence in B6C3F1 versus B6Cf1 Mice. TUMORI JOURNAL 2018; 70:485-90. [PMID: 6531790 DOI: 10.1177/030089168407000603] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The incidences of spontaneous tumors of the murine hybrids (C57BL/6J X C3Hf)F1 (B6C3F1) and (C57BL/6J X BALB/c)F1 (B6CF1) were compared in untreated mice kept until 110 weeks of age. Male B6C3F1 and B6CF1 mice had respectively 16% and 20% incidence of lymphomas, 26% and 4% of liver tumors and 12% and 22% of lung tumors. Among B6C3F1 and B6CF1 females, a 36% and 12% incidence of lymphomas, a 6% and zero incidence of liver tumors, and a 4% and 16% of lung tumors were observed. A few other tumors were seen in both hybrids. Groups of male and female mice of the 2 hybrids received 5 i.p. injections of 1000 mg/kg urethan once every other day starting at 10 days of age, and were kept under observation until 65-80 weeks of age. Treated B6C3F1 mice had an earlier mortality than B6CF1 mice due to tumor development. The statistical analysis, allowing for survival, showed a significantly higher lymphoma incidence in male and female B6C3F1 than B6CF1 mice, which had instead a higher incidence of lung tumors. Hepatocellular tumors were seen in both sexes of the 2 hybrids, with a higher frequency in B6C3F1 mice. Male mice of both hybrids had a higher incidence of liver tumors than females.
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3
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Abstract
This report summarizes data on the testing of 228 chemicals for carcinogenic activity by the strain A mouse lung adenoma bioassay. The assay is of six months duration and can distinguish two-fold dose differences in carcinogenic potential of compounds from a variety of chemical classes. Most compounds that induced lung tumors in strain A mice have also evoked a neoplastic response in other experimental animal bioassays and/or demonstrated mutagenic activity in various short-term tests. Recommendations are made for future studies on the: (a) distribution and metabolism of chemicals in strain A mouse lung tissue and in specific lung cell types, (b) ability of the lung adenoma bioassay to detect promoting agents, and (c) use of the bioassay to investigate the interactions of more than one chemical.
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Affiliation(s)
- Gary D. Stoner
- Department of Pathology, Medical College of Ohio, Toledo, OH 43614
| | - Michael B. Shimkin
- Department of Community Medicine, University of California-San Diego, La Jolla, CA 92093
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Tsui HC, Wu HDI, Lin CJ, Wang RY, Chiu HT, Cheng YC, Chiu TH, Wu FY. Prenatal smoking exposure and neonatal DNA damage in relation to birth outcomes. Pediatr Res 2008; 64:131-4. [PMID: 18414143 DOI: 10.1203/pdr.0b013e3181799535] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This study investigated whether mothers with prenatal environmental tobacco smoke (ETS) exposure increased the newborn genetic damage and adverse birth outcomes. Study participants were women receiving prenatal care at three hospitals in Central Taiwan and their newborns. Participants were divided into two groups (nonsmokers and ETS-exposed non-smokers) based on maternal ETS-exposed status. Comet assay were performed for cord blood samples. Infants born to mothers with prenatal ETS exposure had the highest mean cord blood DNA damage score (69.7 +/- 42.3) and poorer birth outcomes. No negative fetal growth effects appeared among newborns with low DNA damage levels. Among newborns with high DNA damage levels (comet scores >50), those born to prenatal ETS exposure had an average reduction of 252.7 g in birth weight, 1.10 cm shorter in length and a 0.92-cm decrease in head circumference, compared to newborns with no smoking exposure. This study shows that the DNA damage scores can be used as an effect-modifier on the relationships between ETS exposure and adverse birth outcome. The association appears more apparent for the ETS exposure in relation with more severe DNA damage.
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Affiliation(s)
- Huai-Chih Tsui
- Institute of Environmental Health, China Medical University Hospital, Taichung, Taiwan
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5
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Taguchi S, Kuriwaki K, Souda M, Funato M, Ninomiya K, Umekita Y, Yoshida H. Induction of sarcomas by a single subcutaneous injection of 7,12-dimethylbenz[a]anthracene into neonatal male Sprague-Dawley rats: histopathological and immunohistochemical analyses. Toxicol Pathol 2006; 34:336-47. [PMID: 16844661 DOI: 10.1080/01926230600773966] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Animal experiments have shown that carcinogenicity of chemicals is higher in fetal or neonatal periods than adult. We investigated sensitivities to a carcinogen in peri-neonatal rats with a model of sarcomas-induction by a subcutaneous injection of chemo-carcinogen that has rarely done in neonatal rats. Neonatal male SD rats were injected with 7,12-DMBA 10, 100, and 500 microg, which resulted in sarcomas-induction in 0, 62, and 94% of rats. Male SD rats were injected with DMBA 500 microg at 0, 3, 7, 14, and 21 days, which resulted in sarcomas-induction in 94, 70, 64, 50, and 44% of rats. Although the induced sarcomas were occasionally in mixed morphological feature as previous reports for sarcomas of rat, each was immunohistochemically in almost monotonous pattern, and classification was feasible. The incidence of rhabdomyosarcomas was higher in rats neonatally injected with a higher dose of DMBA than a lower dose, and in rats injected at peri-neonatal periods than later periods. In histological observations for the site of injection before overt sarcomas develop, clusters of atypical mesenchymal cells emerged as previous studies, but also those were immunohistochemically differentiated into rhabdomyocytes and other mesenchymal cells. We consider these findings may contribute a little to elucidation of process of sarcomas-induction in rats.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/administration & dosage
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Animals
- Animals, Newborn
- Carcinogens/administration & dosage
- Carcinogens/toxicity
- Dose-Response Relationship, Drug
- Immunohistochemistry
- Incidence
- Injections, Subcutaneous
- Male
- Neoplasms, Experimental/chemically induced
- Neoplasms, Experimental/classification
- Neoplasms, Experimental/epidemiology
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Rats
- Rats, Sprague-Dawley
- Sarcoma/chemically induced
- Sarcoma/classification
- Sarcoma/epidemiology
- Sarcoma/metabolism
- Sarcoma/pathology
- Time Factors
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Affiliation(s)
- Shuuhei Taguchi
- Department of Tumor Pathology, Field of Oncology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, 890-8520, Japan
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6
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McDermott SP, Ranheim EA, Leatherberry VS, Khwaja SS, Klos KS, Alexander CM. Juvenile syndecan-1 null mice are protected from carcinogen-induced tumor development. Oncogene 2006; 26:1407-16. [PMID: 16953225 DOI: 10.1038/sj.onc.1209930] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We previously showed that mice with a null mutation in syndecan-1 (Sdc1; CD138) were resistant to Wnt1-induced mammary tumor initiation. The absence of Sdc1 inhibited the increase in the mammary stem cell fraction that is characteristic of preneoplasia in this model. As the tumor precursor cells are recruited from the stem/progenitor cell compartment, tumor development was also inhibited (Liu et al., 2004; PNAS 101, 4158). Although Sdc1-/- mice are grossly normal, they are systemically smaller, suggesting that developmental abnormalities may extend further than their mammary glands. We have therefore evaluated the multi-organ response of Sdc1-/- mice to carcinogen-induced tumor development (7,12-dimethylbenz[a]anthracene, DMBA), and find these mice to be resistant to tumorigenesis in all the predominant carcinogen-susceptible lineages. Thus, Sdc1-/- mice administered DMBA during juvenile development are resistant not only to epithelial tumors, including liver (60-80%) and lung tumors (C57BL6 mice, 60-80%), but also to lymphoma (over 70%, depending upon strain and carcinogen dose). We demonstrate that CD138 is expressed (heterogeneously) in the hematopoietic stem cell fraction (and not only in pre-B and plasma cells), and that tumors arise in both myeloid and lymphoid lineages. Furthermore, carcinogen-induced mammary tumors are bilineal, implying a bipotent precursor cell. Both observations imply that the DMBA-induced tumor precursor cells are drawn from the stem/progenitor fraction, and we suggest that pathogenic activation of these cells could be abnormal in Sdc1-/- mice.
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Affiliation(s)
- S P McDermott
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison Medical School, Madison, WI 53706, USA
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7
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Barton HA, Cogliano VJ, Flowers L, Valcovic L, Setzer RW, Woodruff TJ. Assessing susceptibility from early-life exposure to carcinogens. ENVIRONMENTAL HEALTH PERSPECTIVES 2005; 113:1125-33. [PMID: 16140616 PMCID: PMC1280390 DOI: 10.1289/ehp.7667] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cancer risk assessment methods currently assume that children and adults are equally susceptible to exposure to chemicals. We reviewed available scientific literature to determine whether this was scientifically supported. We identified more than 50 chemicals causing cancer after perinatal exposure. Human data are extremely limited, with radiation exposures showing increased early susceptibility at some tumor sites. Twenty-seven rodent studies for 18 chemicals had sufficient data after postnatal and adult exposures to quantitatively estimate potential increased susceptibility from early-life exposure, calculated as the ratio of juvenile to adult cancer potencies for three study types: acute dosing, repeated dosing, and lifetime dosing. Twelve of the chemicals act through a mutagenic mode of action. For these, the geometric mean ratio was 11 for lifetime exposures and 8.7 for repeat exposures, with a ratio of 10 for these studies combined. The geometric mean ratio for acute studies is 1.5, which was influenced by tissue-specific results [geometric mean ratios for kidney, leukemia, liver, lymph, mammary, nerve, reticular tissue, thymic lymphoma, and uterus/vagina > 1 (range, 1.6-8.1); forestomach, harderian gland, ovaries, and thyroid < 1 (range, 0.033-0.45)]. Chemicals causing cancer through other modes of action indicate some increased susceptibility from postnatal exposure (geometric mean ratio is 3.4 for lifetime exposure, 2.2 for repeat exposure). Early exposures to compounds with endocrine activity sometimes produce different tumors after exposures at different ages. These analyses suggest increased susceptibility to cancer from early-life exposure, particularly for chemicals acting through a mutagenic mode of action.
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Affiliation(s)
- Hugh A Barton
- Office of Research and Development, National Center for Computational Toxicology, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
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Perera F, Tang D, Whyatt R, Lederman SA, Jedrychowski W. DNA damage from polycyclic aromatic hydrocarbons measured by benzo[a]pyrene-DNA adducts in mothers and newborns from Northern Manhattan, the World Trade Center Area, Poland, and China. Cancer Epidemiol Biomarkers Prev 2005; 14:709-14. [PMID: 15767354 DOI: 10.1158/1055-9965.epi-04-0457] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAH), of which benzo[a]pyrene is a representative member, are combustion-related environmental pollutants and include known carcinogens. Laboratory animal studies indicate that the dose of PAHs to the fetus is on the order of a 10th that to the mother and that there is heightened susceptibility to PAH-induced carcinogenesis during the fetal and infancy periods. Carcinogen-DNA adducts, a measure of procarcinogenic genetic damage, are considered a biomarker of increased cancer risk. Here we compare the levels of benzo[a]pyrene-DNA adducts as a proxy for PAH-DNA damage measured in maternal blood and newborn cord blood obtained at delivery in four different populations of mothers (total of 867) and newborns (total of 822), representing a 30-fold range of exposure to ambient PAHs. The populations include residents in Northern Manhattan, participants in a study of the effects of the World Trade Center disaster, residents in Krakow, Poland, and residents in Tongliang, China. Mean adduct concentrations in both maternal and cord blood and the proportion of samples with detectable adducts, increased across the populations [Northern Manhattan < World Trade Center (WTC) < Krakow < Tongliang], consistent with the trend in estimated ambient exposure to PAHs (P < 0.001). For mothers, the means in the respective populations were Northern Manhattan (0.21 adducts per 10(8) nucleotides), WTC (0.23 adducts per 10(8) nucleotides), Krakow (0.28 adducts per 10(8) nucleotides), Tongliang (0.31 adducts per 10(8) nucleotides); the corresponding means in the newborns were Northern Manhattan (0.23), WTC (0.24), Krakow (0.29), Tongliang (0.31). The percentage of mothers with detectable levels of adducts in the respective populations were Northern Manhattan (36.8%), WTC (57.5%), Krakow (72.9%), Tongliang (73.4%); the corresponding percentages among the newborns were Northern Manhattan (42.4%), WTC (60.6%), Krakow (71.1%), Tongliang (79.5%). Despite the estimated 10-fold lower PAH dose to the fetus based on laboratory animal experiments, the adduct levels in the newborns were similar to or higher than in the mothers. This study suggests that the fetus may be 10-fold more susceptible to DNA damage than the mother and that in utero exposure to polycyclic aromatic hydrocarbons may disproportionately increase carcinogenic risk. The data support preventive policies to limit PAH exposure to pregnant women and children.
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Affiliation(s)
- Frederica Perera
- Department of Environmental Health Sciences, Mailman School of Public Health of Columbia University, Columbia Center for Children's Environmental Health, New York, NY 10032, USA.
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9
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Perera FP, Tang D, Tu YH, Cruz LA, Borjas M, Bernert T, Whyatt RM. Biomarkers in maternal and newborn blood indicate heightened fetal susceptibility to procarcinogenic DNA damage. ENVIRONMENTAL HEALTH PERSPECTIVES 2004; 112:1133-6. [PMID: 15238289 PMCID: PMC1247389 DOI: 10.1289/ehp.6833] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (BaP) are widespread air contaminants released by transportation vehicles, power generation, and other combustion sources. Experimental evidence indicates that the developing fetus is more susceptible than the adult to carcinogenic effects of PAHs, although laboratory studies in rodents suggest that the dose to fetal tissues is an order of magnitude lower than that to maternal tissues. To assess fetal versus adult susceptibility to PAHs and environmental tobacco smoke (ETS), we compared carcinogen-DNA adducts (a biomarker associated with increased cancer risk) and cotinine (a biomarker of tobacco smoke exposure) in paired blood samples collected from mothers and newborns in New York City. We enrolled 265 nonsmoker African-American and Latina mother-newborn pairs in New York City between 1997 and 2001 (estimated average ambient air BaP concentrations < 0.5 ng/m3). Despite the estimated 10-fold lower fetal dose, mean levels of BaP-DNA adducts as determined by high-performance liquid chromatography-fluorescence were comparable in paired New York City newborn and maternal samples (0.24 adducts per 10(8) nucleotides, 45% of newborns with detectable adducts vs. 0.22 per 10(8) nucleotides, 41% of mothers with detectable adducts). However, by the Wilcoxon signed-rank test, the levels in newborns were higher (p = 0.02). Mean cotinine was higher in newborns than in mothers (1.7 ng/mL, 47% detectable vs. 1.28 ng/mL, 44% detectable). Consistent with our prior study in a Caucasian Polish population, these results indicate increased susceptibility of the fetus to DNA damage and reduced ability to clear ETS constituents. The findings have implications for risk assessment, given the need to protect children as a sensitive subset of the population.
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Affiliation(s)
- Frederica P Perera
- Mailman School of Public Health of Columbia University, Department of Environmental Health Sciences, New York, New York 10032, USA.
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10
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Ginsberg GL. Assessing cancer risks from short-term exposures in children. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2003; 23:19-34. [PMID: 12635720 DOI: 10.1111/1539-6924.00287] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
For the vast majority of chemicals that have cancer potency estimates on IRIS, the underlying database is deficient with respect to early-life exposures. This data gap has prevented derivation of cancer potency factors that are relevant to this time period, and so assessments may not fully address children's risks. This article provides a review of juvenile animal bioassay data in comparison to adult animal data for a broad array of carcinogens. This comparison indicates that short-term exposures in early life are likely to yield a greater tumor response than short-term exposures in adults, but similar tumor response when compared to long-term exposures in adults. This evidence is brought into a risk assessment context by proposing an approach that: (1) does not prorate children's exposures over the entire life span or mix them with exposures that occur at other ages; (2) applies the cancer slope factor from adult animal or human epidemiology studies to the children's exposure dose to calculate the cancer risk associated with the early-life period; and (3) adds the cancer risk for young children to that for older children/adults to yield a total lifetime cancer risk. The proposed approach allows for the unique exposure and pharmacokinetic factors associated with young children to be fully weighted in the cancer risk assessment. It is very similar to the approach currently used by U.S. EPA for vinyl chloride. The current analysis finds that the database of early life and adult cancer bioassays supports extension of this approach from vinyl chloride to other carcinogens of diverse mode of action. This approach should be enhanced by early-life data specific to the particular carcinogen under analysis whenever possible.
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Affiliation(s)
- Gary L Ginsberg
- Connecticut Department of Public Health, Division of Environmental Epidemiology & Occupational Health, PO Box 340308, MS 11CHA, Hartford, CT 06134-0308, USA.
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11
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Fu PP, Von Tungeln LS, Hammons GJ, McMahon G, Wogan G, Flammang TJ, Kadlubar FF. Metabolic activation capacity of neonatal mice in relation to the neonatal mouse tumorigenicity bioassay. Drug Metab Rev 2000; 32:241-66. [PMID: 10774778 DOI: 10.1081/dmr-100100575] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The neonatal mouse tumorigenicity bioassay is a well-developed animal model that has recently been recommended as an alternative tumorigenicity bioassay by the International Conference on Harmonization (ICH) for Technical Requirements for the Registration of Pharmaceuticals for Human Use. There are sufficient data to conclude that this animal model is highly sensitive to genotoxic chemical carcinogens that exert their tumorigenicity through mechanisms involving the formation of covalently bound exogenous DNA adducts that lead to mutation. On the other hand, it is not sensitive to chemical carcinogens that exert tumorigenicity through a secondary mechanism. The metabolizing enzymes present in the neonatal mouse, particularly the cytochromes P450, are critical factors in determining the tumorigenic potency of a chemical tested in this bioassay. However, compared to the metabolizing enzymes of the adult mouse and rat, the study of the metabolizing enzymes in neonatal mouse tissues has been relatively limited.
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Affiliation(s)
- P P Fu
- National Center for Toxicological Research, Jefferson, Arkansas 72079, USA
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12
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Fu PP, Von Tungeln LS, Yi P, Xia Q, Casciano AA, Flammang TJ, Kadlubar FF. Neonatal Mouse Tumorigenicity Bioassay. ACTA ACUST UNITED AC 1998. [DOI: 10.1177/009286159803200311] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Flammang TJ, Tungeln LS, Kadlubar FF, Fu PP. Neonatal mouse assay for tumorigenicity: alternative to the chronic rodent bioassay. Regul Toxicol Pharmacol 1997; 26:230-40. [PMID: 9356286 DOI: 10.1006/rtph.1997.1125] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The chronic rodent bioassay for tumors has been utilized systematically for 25 years to identify chemicals with carcinogenic potential in man. In general, those chemicals exhibiting tumorigenicity at multiple sites in both mice and rats have been regarded as possessing strong carcinogenic potential in humans. In comparison, the value of data collected for those test chemicals exhibiting more sporadic tumorigenicity results (e.g., single species/single sex or dose-independent) has been questioned. As knowledge of the carcinogenic process has increased, several alternative test systems, usually faster and less expensive than the 2-year bioassay, have been suggested for identification of the strongly acting, transspecies carcinogens. The International Conference on Harmonization for Technical Requirements for the Registration of Pharmaceuticals for Human Use has proposed an international standard that allows for the use of one long-term rodent carcinogenicity study, plus one supplementary study to identify potential human pharmaceutical carcinogens. The neonatal mouse assay for tumorigenicity has been used since 1959; however, relative to other alternate tests, little has been written about this system. It is clear that this assay system successfully identifies transspecies carcinogens from numerous chemical classes, thus recommending itself as a strong candidate for a supplementary study to identify potential human carcinogens. In contrast, there are decidedly less data available from this assay in response to pharmaceuticals shown to exhibit weak and/or conflicting results in the 2-year bioassay, knowledge invaluable to the regulatory process. This paper reviews the historical development and our experience with the neonatal mouse assay and includes suggestions for a standardized protocol and strategies to document its response to "weak" and/or "nongenotoxic" carcinogens.
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Affiliation(s)
- T J Flammang
- U.S. Food and Drug Administration/National Center for Toxicological Research, Jefferson, Arkansas 72079, USA
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14
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Shou M, Korzekwa KR, Krausz KW, Buters JT, Grogan J, Goldfarb I, Hardwick JP, Gonzalez FJ, Gelboin HV. Specificity of cDNA-expressed human and rodent cytochrome P450s in the oxidative metabolism of the potent carcinogen 7,12-dimethylbenz[a]anthracene. Mol Carcinog 1996; 17:241-9. [PMID: 8989918 DOI: 10.1002/(sici)1098-2744(199612)17:4<241::aid-mc8>3.0.co;2-g] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
7,12-Dimethylbenz[a]anthracene (DMBA), a potent carcinogen, requires metabolic activation by cytochrome P450s (P450s) to electrophilic metabolites that result in DNA modification, mutagenicity, and carcinogenicity. In this study, we used eight human forms, four rodent forms, and one rabbit form of P450 expressed from recombinant vaccinia or baculovirus vectors to define their specificity for metabolizing DMBA. Of the eight human P450s, 1A1 was the most active (specific activity = 14.7 nmol/min/nmol of P450) in total metabolism of DMBA and showed approximately 6- to 33-fold more activity than other P450s, 2B6, 2C9, and 1A2 were also capable of metabolizing DMBA (2.0-2.5 nmol/min/nmol of P450), whereas 2C8, 2E1, 3A4, and 3A5 exhibited relatively low activities. Among animal P450s, mouse 1A1 exhibited activity similar to that of human 1A1 and had 5.0- to 37-fold more activity than other rodent and rabbit P450s. In regard to enzyme regioselectivity, most human and rodent P450s predominantly formed the 8,9-diol, but human 2B6 and rat 2B1 preferentially formed the 5,6-diol. In the production of monohydroxymethyl metabolites, all the enzymes yielded more 7-hydroxymethyl-12-methylbenz[a]anthracene (7HOM12MBA) than 12-hydroxymethyl-7-methylbenz[a]anthracene (7M12HOMBA), except for human 1A1, which presented the reverse selectivity. Human liver microsomes from 10 organ donors were shown to metabolize DMBA and in most circumstances generated the metabolic profile DMBA trans-8,9-dihydrodiol > 7HOM12MBA > or = DMBA trans-5,6-dihydrodiol > or = 7,12-dihydroxymethylbenz[a]anthracene > 7M12HOMBA > DMBA trans-3,4-dihydrodiol. Thus, the combined activity of hepatic microsomal 2C9, 1A2, and 2B6 may contribute to the metabolic activation and the metabolism of DMBA in normal human liver.
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Affiliation(s)
- M Shou
- Laboratory of Molecular Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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15
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Barsoum AL, Kurl RN. Serum poly(A)polymerase levels in rats during induction of mammary carcinoma with 7,12-dimethylbenz[a]anthracene. Cancer Lett 1991; 58:195-7. [PMID: 1906776 DOI: 10.1016/0304-3835(91)90100-v] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Levels of activity of poly(A)polymerase (polynucleotide adenylyl transferase), the enzyme responsible for the addition of poly(A) tracts to the 3'-termini of eukaryotic mRNAs were assayed in the serum of rats during induction of mammary carcinoma by intragastric administration of 7,12-dimethylbenz[a]anthracene (DMBA, 10 mg/rat). An appreciable rise in the levels of poly(A)polymerase coincided with the growth of palpable DMBA-induced mammary carcinoma, which then dropped sharply 2 weeks later when the tumor incidence reached its peak of 65%.
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Affiliation(s)
- A L Barsoum
- Department of Microbiology and Immunology, University of South Alabama, Mobile 36688
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Della Porta G, Dragani TA. Carcinogenicity study in mice on pildralazine, a hydralazinelike antihypertensive compound. J Cancer Res Clin Oncol 1983; 106:97-101. [PMID: 6630287 DOI: 10.1007/bf00395386] [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: 01/21/2023]
Abstract
Pildralazine, a hydralazinelike antihypertensive vasodilator containing a free hydrazine group, was administered in the drinking water to male and female B6C3F1 and to female BALB/c mice at 100, 200, and 400 ppm dose levels for 80 weeks. The animals were kept under observation until 130-133 weeks of age, when the experiment was terminated. A transplacental-infantile bioassay was also carried out with pildralazine administered in the drinking water at 200 and 400 ppm dose levels to female C57BL/6J mice for 1 week before mating with C3Hf males and during mating and pregnancy. The progeny received the same doses for 10 weeks after birth and were kept under observation until 80-85 weeks of age, when the experiment was terminated. In both long-term and transplacental-infantile assays, control and treated groups developed the pattern of tumors usually observed in the strains used and no tumor type at any site appeared to be related to treatment.
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17
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Dragani TA, Sozzi G, Della Porta G. Comparison of urethane-induced sister-chromatid exchanges in various murine strains, and the effect of enzyme inducers. Mutat Res 1983; 121:233-9. [PMID: 6621585 DOI: 10.1016/0165-7992(83)90208-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The induction of sister-chromatid exchanges (SCEs) by urethane, 150 and 300 mg/kg administered i.p., was examined in bone-marrow cells of AKR, BALB/c, C3Hf, C57BL/6J and DBA/2 male mice. In all strains, the base-line level of SCE/cell was similar, ranging from 4.3 to 8.7, and the response increased with the dose of urethane. DBA/2 mice were the most susceptible to urethane at both dose levels, with 30.6 SCE/cell after treatment with 300 mg/kg, whereas the response of the other strains was from 17.4 to 21.5 SCE/cell at the same urethane dose. Pretreatment of C57BL/6J and DBA/2 mice with phenobarbital decreased the SCE frequencies induced by urethane, 300 mg/kg, to 70%, whereas a prior administration of beta-naphthoflavone reduced SCE levels in C57BL/6J but not in DBA/2 mice.
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Abstract
This paper summarizes our contributions in the basic understanding of the different susceptibility of the mammary gland to carcinogenesis according to age and parity history. Mammary carcinomas induced by the administration of 7,12-dimethylbenz-(DMBA) to young virgin rats arise from undifferentiated terminal ductal structures called terminal end buds (TEBs). TEBs, that normally differentiate into alveolar buds (ABs) and lobules, under the influence of DMBA develop intraductal proliferations which progress to carcinoma. The high susceptibility of the young virgin rat TEBs to neoplastic transformation is due to its large proliferative compartment, with cells cycling every 10 hours, and to a higher 3H-DMBA uptake. Progressive differentiation of TEBs into ABs and lobules or their regression to terminal ducts (TDs) is seen with aging. Complete differentiation of the gland is attained through pregnancy and lactation or through exogenous administration of chorionic gonadotrophin. The greater differentiation of the gland is manifested as permanent structural changes, consisting in the disappearance of TEBs and in a diminution of the number of TDs due to their differentiation into ABs and lobules. This greater differentiation results in a diminished or total refractoriness of the gland to the carcinogen because ABs and lobules have a lower proliferative compartment, and a longer cell cycle than TEBs and TDs. Cells of parous rats have both in vivo and in vitro lower DMBA-DNA binding capacity, lower DNA synthesis and greater ability to repair DMBA-damaged DNA than cells of young virgin rats. The more efficient DNA repair capacity of the parous rat mammary gland is demonstrated by the induction of unscheduled DNA synthesis and a removal of DMBA-DNA adducts.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/metabolism
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Animals
- Cell Cycle
- Cell Transformation, Neoplastic/chemically induced
- Chorionic Gonadotropin/administration & dosage
- Chorionic Gonadotropin/pharmacology
- DNA/biosynthesis
- DNA/metabolism
- DNA Repair
- Female
- Mammary Glands, Animal/cytology
- Mammary Glands, Animal/metabolism
- Mammary Neoplasms, Experimental/chemically induced
- Mammary Neoplasms, Experimental/metabolism
- Rats
- Rats, Inbred Strains
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Russo J, Tay LK, Russo IH. Differentiation of the mammary gland and susceptibility to carcinogenesis. Breast Cancer Res Treat 1982; 2:5-73. [PMID: 6216933 DOI: 10.1007/bf01805718] [Citation(s) in RCA: 454] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
It has been demonstrated that in humans certain factors such as early menarche, late pregnancy, and nulliparity are associated with a higher risk of developing breast cancer, while early pregnancy acts as a protective factor. Induction of mammary cancer in rats by administration of the chemical carcinogen 7,12-dimethylbenz(a)anthracene reveals that the same factors influencing human breast cancer risk also affect the susceptibility of the rat mammary gland to the chemical carcinogen. Nulliparous rats and rats undergoing pregnancy interruption are more susceptible to developing carcinomas. This fact has been attributed to the incomplete differentiation of the gland at the time of carcinogen administration. Parous rats are resistant to the carcinogenic effect of DMBA, which is explained by the complete development of the gland attained during pregnancy and lactation. This development is manifested by the differentiation of terminal end buds into secretory units, which have a smaller proliferative compartment; the epithelial cells of these secretory units have a longer cell cycle, less avidity for binding DMBA, and possess a more efficient DNA excision repair capacity.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/metabolism
- 9,10-Dimethyl-1,2-benzanthracene/pharmacology
- Abortion, Induced
- Adenosine Triphosphatases/analysis
- Aging
- Animals
- Antigens
- Breast Neoplasms/etiology
- Cell Cycle
- DNA/biosynthesis
- DNA Repair
- Disease Susceptibility
- Epithelial Cells
- Female
- Humans
- Mammary Glands, Animal/cytology
- Mammary Glands, Animal/growth & development
- Mammary Glands, Animal/immunology
- Mammary Neoplasms, Experimental/chemically induced
- Mammary Neoplasms, Experimental/etiology
- Maternal Age
- Parity
- Pregnancy
- Rats
- Rats, Inbred Strains
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Abstract
Microbial transformations of 7,12-dimethylbenz[a]anthracene, a carcinogenic polycyclic aromatic hydrocarbon, in cultures of Pseudomonas aeruginosa and Penicillium notatum were studied by high performance liquid chromatographic separation of metabolic fractions followed by gas chromatographic-mass spectrometric analysis of the metabolites. Two methyl-hydroxylated metabolites were identified in each of the incubations. The metabolic activation of the polycyclic aromatic hydrocarbon suggests a possible involvement of microorganisms in environmental carcinogenesis.
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Conybeare G. Effect of quality and quantity of diet on survival and tumour incidence in outbred Swiss mice. FOOD AND COSMETICS TOXICOLOGY 1980; 18:65-75. [PMID: 7372212 DOI: 10.1016/0015-6264(80)90013-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Huberman E, Chou MW, Yang SK. Identification of 7,12-dimethylbenz[a]anthracene metabolites that lead to mutagenesis in mammalian cells. Proc Natl Acad Sci U S A 1979; 76:862-6. [PMID: 106395 PMCID: PMC383073 DOI: 10.1073/pnas.76.2.862] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mutagenicity of 7,12-dimethylbenz[a]-anthracene (DMBA) and 11 of its enzymatically derived metabolites was tested with Chinese hamster V79 cells for identification of mutagenic metabolites. The metabolites consisted of 7-hydroxymethyl-12-methylbenz[a]anthracene, 7-methyl-12-hydroxymethylbenz[a]anthracene, 7,12-dihydroxymethylbenz[a]anthracene, three trans-3,4-diols, two trans-5,6-diols, and three trans-8,9-diols, all of which derived from DMBA or from the hydroxymethyl derivatives. Mutations were characterized by resistance to ouabain and 6-thioguanine. None of the tested metabolites were mutagenic in V79 cells, which do not metabolize polycyclic aromatic hydrocarbons. Therefore, mutagenesis in the V79 cells was tested in the presence of golden hamster cells capable of metabolizing polycyclic aromatic hydrocarbons (cell-mediated assay). In this assay, DMBA, 7-hydroxymethyl-12-methylbenz[a]anthracene, 7-methyl-12-hydroxymethylbenz[a]anthracene, and their trans3,4-diols were mutagenic for both genetic markers, and the mutagenic response increased as a function of the hydrocarbon dose. All other metabolites were either inactive or showed up to a 4-fold higher mutation frequency than the untreated V79 cells for ouabain and 6-thioguanine resistance. The DMBA-trans-3,4-diol was the only metabolite that was more active than DMBA itself; at 0.05 muM it was 6-8 times more active than DMBA itself; at 0.05 muM it was 6-8 times more active than DMBA in inducing both ouabain and 6-thioguanine resistance. This diol was mutagenic at a dose as low as 0.01 muM. Mutagenesis by DMBA and the trans-3,4-diols was inhibited by 7,8-benzoflavone, an inhibitor of mixed-function oxidases. Analysis of DMBA metabolism in intact golden hamster cells indicated that DMBA-trans-3,4-diol is one of the major metabolites produced. Our results therefore suggest that DMBA-trans-3,4-diol may be metabolized to a diol-epoxide, presumably the trans-3,4-diol-1,2-epoxide, which may be a major reactive metabolite responsible for DMBA mutagenicity in mammalian cells.
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Haddow A. Molecular repair, wound healing, and carcinogenesis: tumor production a possible overhealing? Adv Cancer Res 1973; 16:181-234. [PMID: 4563044 DOI: 10.1016/s0065-230x(08)60341-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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26
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Terracini B, Testa MC. Carcinogenicity of a single administration of N-nitrosomethylurea: a comparison between newborn and 5-week-old mice and rats. Br J Cancer 1970; 24:588-98. [PMID: 4319944 PMCID: PMC2008619 DOI: 10.1038/bjc.1970.71] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
N-Nitrosomethylurea (NMUrea) was given as a single intraperitoneal injection either to newborn or to 5-week-old (C57BL * C3Hf)F(1) mice and Wistar rats. Newborn mice were more susceptible than 5-week-old mice to the development of lymphosarcomas, lung adenomas and hepatomas, whereas newborn rats were more susceptible than their weaned counterparts to the development of renal anaplastic tumours. Other tumours occured with the same frequency in newborn and mature animals. Tumours of the forestomach in mice were more frequenty found in animals treated at 5 weeks than in those treated at birth. Since NMUrea persists for only a very short time and breaks down spontaneously it seems that the paucity of enzymes related to immaturity in newborns is not a major factor in determining the different susceptibility of newborn animals to NMUrea carcinogenicity.
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Darlow HM, Simmons DJ, Roe FJ. Hazards from experimental skin painting of carcinogens. A study based on use of a spore model. ARCHIVES OF ENVIRONMENTAL HEALTH 1969; 18:883-93. [PMID: 4976990 DOI: 10.1080/00039896.1969.10665510] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Della Porta G. Use of newborn and infant animals in carcinogenicity testing. FOOD AND COSMETICS TOXICOLOGY 1968; 6:243-52. [PMID: 4299531 DOI: 10.1016/0015-6264(68)90205-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Grant GA, Carter RL, Roe FJ, Pike MC. Effects of the neonatal injection of a carcinogen on the induction of tumours by the subsequent application to the skin of the same carcinogen. Br J Cancer 1968; 22:346-58. [PMID: 5660140 PMCID: PMC2008259 DOI: 10.1038/bjc.1968.43] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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Walters MA, Roe FJ, Mitchley BC, Walsh A. Further tests for carcinogenesis using newborn mice: 2-naphthylamine, 2-naphthylhydroxylamine, 2-acetylaminofluorene and ethyl methane sulphonate. Br J Cancer 1967; 21:367-72. [PMID: 6028088 PMCID: PMC2008108 DOI: 10.1038/bjc.1967.42] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Walters MA, Roe FJ. The induction of skin tumours in mice by neonatal injection of 9,10-dimethyl-1,2-benzanthracene (DMBA) followed by applications of croton oil to the skin. Br J Cancer 1967; 21:358-66. [PMID: 6028087 PMCID: PMC2008106 DOI: 10.1038/bjc.1967.41] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Walters MA, Roe FJ. The time of appearance of lung tumours in mice injected when newly born with 9,10-dimethyl-1,2-benzathracene (DMBA). Br J Cancer 1966; 20:161-7. [PMID: 5936677 PMCID: PMC2008065 DOI: 10.1038/bjc.1966.18] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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