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Abstract
The three RAS genes - HRAS, NRAS and KRAS - are collectively mutated in one-third of human cancers, where they act as prototypic oncogenes. Interestingly, there are rather distinct patterns to RAS mutations; the isoform mutated as well as the position and type of substitution vary between different cancers. As RAS genes are among the earliest, if not the first, genes mutated in a variety of cancers, understanding how these mutation patterns arise could inform on not only how cancer begins but also the factors influencing this event, which has implications for cancer prevention. To this end, we suggest that there is a narrow window or 'sweet spot' by which oncogenic RAS signalling can promote tumour initiation in normal cells. As a consequence, RAS mutation patterns in each normal cell are a product of the specific RAS isoform mutated, as well as the position of the mutation and type of substitution to achieve an ideal level of signalling.
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Affiliation(s)
- Siqi Li
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Allan Balmain
- Helen Diller Family Comprehensive Cancer Center and Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - Christopher M Counter
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA.
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2
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Calabrese EJ. The additive to background assumption in cancer risk assessment: A reappraisal. ENVIRONMENTAL RESEARCH 2018; 166:175-204. [PMID: 29890424 DOI: 10.1016/j.envres.2018.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/08/2018] [Accepted: 05/11/2018] [Indexed: 05/21/2023]
Abstract
The assumption that chemical and radiation induced cancers act in a manner that is additive to background was proposed in the mid-1970s. It was adopted by the U.S. Environmental Protection Agency (EPA) in 1986 and then subsequently by other regulatory agencies worldwide for cancer risk assessment. It ensured that cancer risks at low doses act in a linear fashion. The additive to background process assumes that the mechanism(s) resulting in induced (i.e., treatment related) and spontaneous (i.e., control group) cancers are identical. This assumption could not be properly evaluated due to inadequate mechanistic data when it was proposed in the 1970s. Using the findings of modern molecular toxicology, including oncogene activation/mutation, gene regulation, and molecular pathway analyses, the additive to background assumption was evaluated in the present paper. Based on published studies with 45 carcinogens over 13 diverse mammalian models and for a broad range of tumor types compelling evidence indicates that carcinogen-induced tumors are mediated in general via mechanisms that are not identical to those affecting the occurrence of the same type of spontaneous tumors in appropriate control groups. These findings, which challenge a fundamental assumption of the additive to background concept, have significant implications for cancer risk assessment policy, regulatory agency practices, as well as fundamental concepts of cancer biology.
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Affiliation(s)
- Edward J Calabrese
- Department of Environmental Health Sciences, University of Massachusetts, Morrill I, N344, Amherst, MA 01003, United States.
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3
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Ramalingam A, Duhadaway JB, Sutanto-Ward E, Wang Y, Dinchuk J, Huang M, Donover PS, Boulden J, McNally LM, Soler AP, Muller AJ, Duncan MK, Prendergast GC. Bin3 Deletion Causes Cataracts and Increased Susceptibility to Lymphoma during Aging. Cancer Res 2008; 68:1683-90. [DOI: 10.1158/0008-5472.can-07-6072] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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4
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Jackson MA, Lea I, Rashid A, Peddada SD, Dunnick JK. Genetic alterations in cancer knowledge system: analysis of gene mutations in mouse and human liver and lung tumors. Toxicol Sci 2006; 90:400-18. [PMID: 16410370 DOI: 10.1093/toxsci/kfj101] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mutational incidence and spectra for genes examined in both human and mouse lung and liver tumors were analyzed using the National Institute of Environmental Health Sciences (NIEHS) Genetic Alterations in Cancer (GAC) knowledge system. GAC is a publicly available, web-based system for evaluating data obtained from peer-reviewed studies of genetic changes in tumors associated with exposure to chemical, physical, or biological agents, as well as spontaneous tumors. In mice, mutations in Kras2 and Hras-1 were the most common events reported for lung and liver tumors, respectively, whether chemically induced or spontaneous. There was a significant difference in Kras2 mutation incidence for spontaneous versus induced mouse lung tumors and in Hras-1 mutation incidence and spectrum for spontaneous versus induced mouse liver tumors. The major gene changes reported for human lung and liver tumors were in KRAS2 (lung only) and TP53. The KRAS2 mutation incidence was similar for spontaneous and asbestos-induced human lung tumors, while the TP53 mutation incidence differed significantly. Aflatoxin B1, hepatitis B virus, hepatitis C virus, and vinyl chloride all caused TP53 mutations in human liver tumors, but the mutation spectrum for each agent differed. The incidence of KRAS2 mutations in human compared to mouse lung tumors differed significantly, as did the incidence of Hras and p53 gene mutations in human compared to mouse liver tumors. Differences observed in the mutation spectra for agent-induced compared to spontaneous tumors and similarities in spectra for structurally similar agents support the concept that mutation spectra can serve as a "fingerprint" of exposure based on chemical structure.
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Affiliation(s)
- Marcus A Jackson
- Integrated Laboratory Systems, Inc., Research Triangle Park, North Carolina 27709, USA
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5
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Liu Z, Kullman SW, Bencic DC, Torten M, Hinton DE. ras oncogene mutations in diethylnitrosamine-induced hepatic tumors in medaka (Oryzias latipes), a teleost fish. Mutat Res 2003; 539:43-53. [PMID: 12948813 DOI: 10.1016/s1383-5718(03)00133-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Medaka fish are an established non-mammalian research model for the study of liver carcinogenesis and exposure to environmental pollutants. Studies have emphasized the development of hepatic neoplasms in medaka following exposure to model carcinogens. To date however, little information is known regarding the mechanisms underlying initiation of hepatic tumors in this species. The aim of this study was to relate our understanding of diethylnitrosamine (DEN)-induced tumor formation to ras gene activation in hepatic neoplasms of exposed medaka. Initial studies were conducted to identify medaka ras exons 1 and 2 by reverse transcriptase polymerase chain reaction (RT-PCR). Amplification of ras exons 1 and 2 from untreated medaka liver resulted in the identification of three polymorphic ras sequence variants exhibiting a high degree of homology to other teleost and mammalian ras genes. Exposure of medaka to 159 ppm of DEN resulted in a wide range of hepatic neoplasms including: hepatocellular adenomas, hepatocellular carcinomas, cholangiomas, and mixed hepatocholangiocellular carcinomas. Individual liver tumors were examined for oncogenically activating ras mutations by probing genomic DNA with probes specific for activating point mutations or by direct cloning and sequencing of ras transcripts using RT-PCR. Using allele-specific oligonucleotide (ASO) analysis, a single point mutation was detected in codon 12 position two in 8/25 (32%) tumors examined. Mutated ras alleles were additionally detected in 12 of 39 (30%) medaka liver tumors by sequence analysis. Ten of the 12 mutations identified contained a single point mutation at codon 12 resulting in a Gly to Asp amino acid substitution. Two unique mutations were identified at codon 16 resulting in either Lys to Asn or Lys to Thr amino acid substitutions. Our results show that ras mutations are induced by DEN and are present in over 30% of the fish that developed tumors. A ras mutation incidence of 30% is similar to that reported in mammalian species exposed to DEN. While mutations at codon 12 have previously been reported, the present study is the first in vivo report of ras point mutations at codon 16.
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Affiliation(s)
- Zi Liu
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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6
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Lee GH, Nishimori H, Sasaki Y, Matsushita H, Kitagawa T, Tokino T. Analysis of lung tumorigenesis in chimeric mice indicates the Pulmonary adenoma resistance 2 (Par2) locus to operate in the tumor-initiation stage in a cell-autonomous manner: detection of polymorphisms in the Poli gene as a candidate for Par2. Oncogene 2003; 22:2374-82. [PMID: 12700672 DOI: 10.1038/sj.onc.1206387] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Pulmonary adenoma resistance 2 (Par2) locus of the BALB/cByJ mouse, located within 0.5 cM of chromosome 18, is responsible for reducing the mean multiplicity of urethane-induced lung tumors relative to those in C57BL/6J, A/J and C3H/HeJ mice. Thus, BALB/B6-Par2 congenic strain genetically identical to BALB/cByJ except carrying C57BL/6J Par2 alleles develops seven times more tumors than BALB/cByJ. To gain clues for identification of Par2 candidate genes, we analysed lung tumorigenesis in BALB/cByJ<-->BALB.B6-Par2 chimeric animals. Of 100 tumors induced by urethane in 16 chimeras, 82 originated from BALB.B6-Par2 cells, indicating the Par2 phenotype to be cell-autonomous. In addition, the BALB.B6-Par2- and BALB/cByJ-derived tumors were similar in mean size, implying that the phenotype is primarily expressed during initiation rather than in the promotion stage of carcinogenesis. Given these results, we surveyed a comprehensive mouse genome database and physically mapped Par2 within a 2.3 Mbp segment containing three known genes, Poli, Mbd2 and Dcc. Among those, the Poli seemed to be the most reasonable Par2 candidate, since it encodes an extremely error-prone DNA polymerase preferentially incorporating G or T opposite template T in vitro, reminiscent of the Kras2 activation because of an A to G or T point mutation within codon 61 with which most urethane-induced lung tumors are initiated. Indeed, our sequencing of Poli cDNAs from BALB/cByJ, C57BL/6J, A/J and C3H/HeJ lungs revealed 21 BALB/cByJ-specific single-nucleotide polymorphisms in the coding region accompanied by seven amino-acid substitutions and an elevated frequency of alternative splicing, while no polymorphisms associated with tumor susceptibility were found for either Mbd2 or Dcc. Notably, we obtained evidence that BALB/cByJ Par2 alleles may selectively decrease the frequency of Kras2-mutated tumors compared with C57BL/6J alleles. Consequently, the Poli is an intriguing Par2 candidate clearly deserving further evaluation.
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MESH Headings
- Adenoma/chemically induced
- Adenoma/genetics
- Alleles
- Alternative Splicing
- Amino Acid Substitution
- Animals
- Animals, Congenic
- Chimera
- Codon/genetics
- DNA, Complementary/genetics
- DNA-Directed DNA Polymerase/chemistry
- DNA-Directed DNA Polymerase/genetics
- DNA-Directed DNA Polymerase/physiology
- Female
- Genes, ras
- Genetic Predisposition to Disease
- Genome
- Immunity, Innate
- Lung Neoplasms/chemically induced
- Lung Neoplasms/genetics
- Male
- Mice
- Mice, Inbred A
- Mice, Inbred BALB C
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Inbred Strains/genetics
- Neoplasms, Multiple Primary/chemically induced
- Neoplasms, Multiple Primary/genetics
- Phenotype
- Physical Chromosome Mapping
- Point Mutation
- Polymorphism, Single Nucleotide
- Reverse Transcriptase Polymerase Chain Reaction
- Urethane
- DNA Polymerase iota
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Affiliation(s)
- Gang-Hong Lee
- Department of Pathology, Toramomon Hospital and Okinaka Memorial Institute for Medical Research 2-2-2 Toranomon, Minatoku, Tokyo 105-8470, Japan.
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7
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Palackal NT, Lee SH, Harvey RG, Blair IA, Penning TM. Activation of polycyclic aromatic hydrocarbon trans-dihydrodiol proximate carcinogens by human aldo-keto reductase (AKR1C) enzymes and their functional overexpression in human lung carcinoma (A549) cells. J Biol Chem 2002; 277:24799-808. [PMID: 11978787 DOI: 10.1074/jbc.m112424200] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAH) are environmental pollutants and suspected human lung carcinogens. In patients with non-small cell lung carcinoma, differential display shows that aldo-keto reductase (AKR1C) transcripts are dramatically overexpressed. However, whether AKR1C isoforms contribute to the carcinogenic process and oxidize potent PAH trans-dihydrodiols (proximate carcinogens) to reactive and redox active o-quinones is unknown; nor is it known whether these reactions occur in human lungs. We now show that four homogeneous human recombinant aldo-keto reductases (AKR1C1-AKR1C4) are regioselective and oxidize only the relevant non-K region trans-dihydrodiols. However, these enzymes are not stereo-selective, since they oxidized 100% of these racemic substrates. The highest utilization ratios (V(max)/K(m)) were observed for some of the most potent proximate carcinogens known (e.g. 7,12-dimethylbenz[a]anthracene-3,4-diol (DMBA-3,4-diol) and benzo[g]chrysene-11,12-diol). In vitro, DMBA-3,4-diol was oxidized by AKR1C4 to the highly reactive 7,12-dimethylbenz[a]anthracene-3,4-dione (DMBA-3,4-dione), which was trapped in situ as its mono- and bis-thioether conjugates, which arise from the sequential 1,6- and 1,4-Michael addition of thiol nucleophiles. Human multiple tissue expression array analysis showed that AKR1C isoform transcripts were highly expressed in the human lung carcinoma cell line A549. Isoform-specific reverse transcriptase-PCR showed that AKR1C1, AKR1C2, and AKR1C3 transcripts were all expressed. Western blot analysis and functional assays confirmed high expression of AKR1C protein and enzyme activity in these lung cells. A549 cell lysates were found to convert DMBA-3,4-diol to the corresponding o-quinone. In trapping experiments, LC/MS analysis identified peaks in the cell lysates that corresponded to the synthetically prepared mono- and bis-thioether conjugates of DMBA-3,4-dione. This quinone is one of the most electrophilic and redox-active o-quinones produced by AKRs. Its unique ability to form bis-thioether conjugates parallels the formation of bis- and tris-glutathionyl conjugates of hydroquinone, which display end organ toxicity. The ability to measure DMBA-3,4-dione formation in A549 cells implicates the AKR pathway in the metabolic activation of PAH in human lung.
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Affiliation(s)
- Nisha T Palackal
- Departments of Biochemistry and Biophysics and Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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8
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Fisher GH, Wellen SL, Klimstra D, Lenczowski JM, Tichelaar JW, Lizak MJ, Whitsett JA, Koretsky A, Varmus HE. Induction and apoptotic regression of lung adenocarcinomas by regulation of a K-Ras transgene in the presence and absence of tumor suppressor genes. Genes Dev 2001; 15:3249-62. [PMID: 11751631 PMCID: PMC312852 DOI: 10.1101/gad.947701] [Citation(s) in RCA: 457] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
To investigate the role of an activated K-Ras gene in the initiation and maintenance of lung adenocarcinomas, we developed transgenic mice that express murine K-Ras4b(G12D) under the control of doxycycline in type II pneumocytes. Focal proliferative lesions of alveolar type II pneumocytes were observed as early as seven days after induction with doxycycline; after two months of induction, the lungs contained adenomas and adenocarcinomas, with focal invasion of the pleura at later stages. Removal of doxycycline caused a rapid fall in levels of mutant K-Ras RNA and concomitant apoptotic regression of both the early proliferative lesions and the tumors. Tumor burden was dramatically decreased by three days after withdrawal, and tumors were undetectable after one month. When similar experiments were performed with animals deficient in either the p53 gene or the Ink4A/Arf locus, tumors arose more quickly (within one month of exposure to doxycycline) and displayed more obvious histological features of malignancy; nevertheless, these tumors also regressed rapidly when the inducer was removed, implying that continued production of mutant K-Ras is necessary to maintain the viability of tumor cells in the absence as well as the presence of tumor suppressor genes. We also show that the appearance and regression of these pulmonary tumors can be readily monitored in anesthetized transgenic animals by magnetic resonance imaging.
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Affiliation(s)
- G H Fisher
- Varmus Laboratory, National Cancer Institute, Division of Basic Sciences, National Institutes of Health, Bethesda, Maryland 20892, USA
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9
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Gulezian D, Jacobson-Kram D, McCullough CB, Olson H, Recio L, Robinson D, Storer R, Tennant R, Ward JM, Neumann DA. Use of transgenic animals for carcinogenicity testing: considerations and implications for risk assessment. Toxicol Pathol 2000; 28:482-99. [PMID: 10862569 DOI: 10.1177/019262330002800320] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Advances in genetic engineering have created opportunities for improved understanding of the molecular basis of carcinogenesis. Through selective introduction, activation, and inactivation of specific genes, investigators can produce mice of unique genotypes and phenotypes that afford insights into the events and mechanisms responsible for tumor formation. It has been suggested that such animals might be used for routine testing of chemicals to determine their carcinogenic potential because the animals may be mechanistically relevant for understanding and predicting the human response to exposure to the chemical being tested. Before transgenic and knockout mice can be used as an adjunct or alternative to the conventional 2-year rodent bioassay, information related to the animal line to be used, study design, and data analysis and interpretation must be carefully considered. Here, we identify and review such information relative to Tg.AC and rasH2 transgenic mice and p53+/- and XPA-/- knockout mice, all of which have been proposed for use in chemical carcinogenicity testing. In addition, the implications of findings of tumors in transgenic and knockout animals when exposed to chemicals is discussed in the context of human health risk assessment.
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Affiliation(s)
- D Gulezian
- Taconic Farms, Inc, Madison, Connecticut 06443, USA
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10
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Storer RD. Current status and use of short/medium term models for carcinogenicity testing of pharmaceuticals--scientific perspective. Toxicol Lett 2000; 112-113:557-66. [PMID: 10720780 DOI: 10.1016/s0378-4274(99)00227-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Short- and medium-term rodent bioassays have been proposed under ICH guidelines for use in testing for the carcinogenic potential of pharmaceuticals. Further evaluation of these models is needed urgently and coordinated efforts are in progress worldwide to expand the available database. Models currently being investigated include transgenic mice (Tg-rasH2, Tg.AC, p53(+/-), XPA(-/-)) and neonatal mice. As more data become available on the performance of these assays, regulatory and industry scientists will be faced with the difficult challenge of determining how the performance (accuracy) of each assay will be measured and deciding which assays have value in the risk assessment process.
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Affiliation(s)
- R D Storer
- Department of Genetic and Cellular Toxicology, Merck Research Laboratories, WP45-311, West Point, PA, USA.
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11
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Zhang Z, Diwan BA, Anderson LM, Logsdon D, Olivero OA, Haines DC, Rice JM, Yuspa SH, Poirier MC. Skin tumorigenesis and Ki-ras and Ha-ras mutations in tumors from adult mice exposed in utero to 3′-azido-2′,3′-dideoxythymidine. Mol Carcinog 1998. [DOI: 10.1002/(sici)1098-2744(199809)23:1<45::aid-mc6>3.0.co;2-g] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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12
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Rivera JA, Graeme-Cook F, Werner J, Z'graggen K, Rustgi AK, Rattner DW, Warshaw AL, Fernández-del Castillo C. A rat model of pancreatic ductal adenocarcinoma: targeting chemical carcinogens. Surgery 1997; 122:82-90. [PMID: 9225919 DOI: 10.1016/s0039-6060(97)90268-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Current experimental models of pancreatic cancer either fail to reproduce the ductal phenotype or cause simultaneous cancers in other organs also. To develop an animal of pancreatic cancer that accurately mimics the human condition, we restricted carcinogenic exposure to the pancreas and specifically targeted ductal epithelial cells. Three different carcinogens were either implanted directly into the pancreas or infused into the pancreatic duct, with or without near-total pancreatectomy (as a means of inducing pancreatic ductal cell proliferation). METHODS Groups of male Sprague-Dawley rats were exposed to varying doses of dimethylbenzanthracine (DMBA), methynitronitrosoguanidine, or ethylnitronitrosoguanidine either through direct implantation into the pancreas or infusion into the pancreatic duct. Near-total pancreatectomy was added in all groups except two DMBA implantation groups. Surviving rats were killed at 3, 6, 9, or 12 months, and the pancreata were evaluated histologically. RESULTS All three carcinogens caused pancreatic inflammation, ductal hyperplasia, atypia, and dysplasia beginning by 3 months and becoming more prominent at later time points. Only DMBA caused frequent invasive pancreatic ductal adenocarcinoma, which was first evident by 6 months. The prevalence of pancreatic cancer among DMBA-treated rats evaluated after 10 months was 39% (19 of 49). The addition of pancreatic resection did not enhance pancreatic cancer development. CONCLUSIONS Of the strategies tested, only direct implantation of DMBA into the rat pancreas frequently produces pancreatic cancer histologically similar to human ductal adenocarcinoma. The development of hyperplastic, atypical, and dysplastic changes preceding and accompanying carcinomas suggests that these lesions are preneoplastic. This model recapitulates the progression from normal to neoplastic epithelium and is likely to be useful for the study of morphologic and molecular mechanisms underlying the early stages of pancreatic carcinogenesis and for the investigation of novel diagnostic and therapeutic techniques.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/adverse effects
- 9,10-Dimethyl-1,2-benzanthracene/pharmacology
- Animals
- Carcinogens/adverse effects
- Carcinogens/pharmacology
- Carcinoma, Ductal, Breast/chemically induced
- Carcinoma, Ductal, Breast/pathology
- Carcinoma, Ductal, Breast/surgery
- Disease Models, Animal
- Fibrosarcoma/chemically induced
- Fibrosarcoma/pathology
- Fibrosarcoma/surgery
- Hyperplasia
- Male
- Methylnitronitrosoguanidine/adverse effects
- Methylnitronitrosoguanidine/analogs & derivatives
- Methylnitronitrosoguanidine/pharmacology
- Pancreatectomy
- Pancreatic Ducts/pathology
- Pancreatic Ducts/surgery
- Pancreatic Neoplasms/chemically induced
- Pancreatic Neoplasms/pathology
- Pancreatic Neoplasms/surgery
- Rats
- Rats, Sprague-Dawley
- Sarcoma, Experimental/chemically induced
- Sarcoma, Experimental/pathology
- Sarcoma, Experimental/surgery
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Affiliation(s)
- J A Rivera
- Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA
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13
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Chen JX, Kisleyou AS, Harvey RG, Slaga TJ, Morris RJ, Tang M. Using UvrABC nuclease to detect 7,12-dimethylbenz[a]anthracene anti-diol epoxide-DNA binding specificity in the mouse H-ras gene. Chem Res Toxicol 1996; 9:1350-4. [PMID: 8951239 DOI: 10.1021/tx9601115] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
DNA fragments modified with chemically synthesized 7,12-dimethylbenz[a]anthracene anti-diol epoxide (anti-DMBADE) are sensitive to UvrABC nuclease incision. The incisions occur mainly 7 bases 5' and 4 bases 3' of an anti-DMBADE-modified adenine or guanine residue, and the kinetics of incision at different sequences in a DNA fragment are the same. These results indicate that UvrABC incision on anti-DMBADE-DNA adducts is independent of DNA sequences and is quantitative, the same as on syn-DMBADE-DNA adducts. This method was used to analyze the anti-DMBADE-DNA binding spectrum in the exon 2 region of the mouse H-ras gene, and it was found that anti-DMBADE binds to the two adenine residues at codon 61 of the H-ras gene with an average affinity. Previously, we have demonstrated that syn-DMBADE binds strongly to the adenines at codon 61 of H-ras; these results together suggest that the oncogenic mutation in H-ras may be induced by anti- and syn-DMBADE-DNA adducts.
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Affiliation(s)
- J X Chen
- Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville 78957, USA
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14
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Chen JX, Pao A, Zheng Y, Ye X, Kisleyou AS, Morris R, Slaga TJ, Harvey RG, Tang MS. Sequence preference of 7,12-dimethylbenz[a]anthracene-syn-diol epoxide-DNA binding in the mouse H-ras gene detected by UvrABC nucleases. Biochemistry 1996; 35:9594-602. [PMID: 8755741 DOI: 10.1021/bi9604136] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have found that 7,12-dimethylbenz[a]anthracene-syn-diol epoxide (syn-DMBADE)-modified DNA fragments are sensitive to UvrABC incision. The incisions occur mainly seven bases 5' and four bases 3' of a syn-DMBADE-modified adenine or guanine residue. The kinetics of UvrABC incision at different sequences in a DNA fragment are the same, and the extent of UvrABC incision is proportional to the syn-DMBADE concentration. On the basis of these results, we have concluded that UvrABC incision on syn-DMBADE-DNA adducts is independent of DNA sequence and is quantitative. Using the UvrABC incision method, we have analyzed the syn-DMBADE-DNA binding spectrum in several defined DNA fragments, including the first two exons of the mouse H-ras gene. We have found that both guanine and adenine residues in codons 12, 13, and 61 of the H-ras gene are strong syn-DMBADE binding sites. These results suggest that the initial binding of DMBADE may greatly contribute to the frequency of H-ras mutations. Results from dinucleotide binding analysis indicate that the 5'-nearest neighbor displays a greater effect on syn-DMBADE-DNA binding than the 3'-nearest neighbor.
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Affiliation(s)
- J X Chen
- Department of Carcinogenesis, University of Texas M. D. Anderson Cancer Center, Science Park-Research Division, Smithville 78957, USA
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15
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Affiliation(s)
- T A Dragani
- Division of Experimental Oncology A, Istituto Nazionale Tumori, Milan, Italy
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16
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Lehman TA, Greenblatt M, Bennett WP, Harris CC. Mutational spectrum of the p53 tumor suppressor gene: clues to cancer etiology and molecular pathogenesis. Drug Metab Rev 1994; 26:221-35. [PMID: 8082567 DOI: 10.3109/03602539409029793] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- T A Lehman
- Laboratory of Human Carcinogenesis, National Cancer Institute, Bethesda, Maryland 20892
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