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Harris KL, Harris KJ, Banks LD, Adunyah SE, Ramesh A. Acceleration of benzo(a)pyrene-induced colon carcinogenesis by Western diet in a rat model of colon cancer. Curr Res Toxicol 2024; 6:100162. [PMID: 38496007 PMCID: PMC10943645 DOI: 10.1016/j.crtox.2024.100162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/02/2024] [Accepted: 03/06/2024] [Indexed: 03/19/2024] Open
Abstract
Colorectal cancer (CRC) is the third leading cause of cancer-related mortalities in the USA and around 52,550 people were expected to die from this disease by December 2023. The objective of this study was to investigate the effect of diet type on benzo(a)pyrene [B(a)P]-induced colon cancer in an adult male rat model, the Polyposis In the Rat Colon (PIRC) kindred type. Groups of PIRC rats (n = 10) were fed with AIN-76A regular diet (RD) or Western diet (WD) and received 25, 50 and 100 µg B(a)P/kg body wt. via oral gavage for 60 days. Rats fed diets alone, but no B(a)P, served as controls. After exposure, rats were euthanized; colon and liver samples were analyzed for activation of drug metabolizing enzymes (DMEs) CYP1A1, CYP1B1, SULT and GST. Plasma and tissue samples were analyzed by reverse phase-HPLC for B(a)P metabolites. In addition to these studies, DNA isolated from colon and liver tissues was analyzed for B(a)P-induced DNA adducts by the 32P-postlabeling method using a thin-layer chromatography system. Western diet consumption resulted in a marked increase in DME expression and B(a)P metabolite concentrations in rats that were administered 100 µg/kg B(a)P + WD (p < 0.05) compared to other treatment groups. Our findings demonstrate that WD accelerates the development of colon tumors induced by B(a)P through enhanced biotransformation, and the products of this process (metabolites) were found to bind with DNA and form B(a)P-DNA adducts, which may have given rise to colon polyps characterized by gain in tumor number, sizes, and dysplasia.
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Affiliation(s)
- Kelly L Harris
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, United States
| | - Kenneth J Harris
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, United States
| | - Leah D Banks
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, United States
| | - Samuel E Adunyah
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, United States
| | - Aramandla Ramesh
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, United States
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2
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Attia H, ElBanna SA, Khattab RA, Farag MA, Yassin AS, Aziz RK. Integrating Microbiome Analysis, Metabolomics, Bioinformatics, and Histopathology to Elucidate the Protective Effects of Pomegranate Juice against Benzo-alpha-pyrene-Induced Colon Pathologies. Int J Mol Sci 2023; 24:10691. [PMID: 37445869 DOI: 10.3390/ijms241310691] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Polycyclic aromatic hydrocarbons, e.g., benzo[a]pyrene (BaP), are common dietary pollutants with potential carcinogenic activity, while polyphenols are potential chemopreventive antioxidants. Although several health benefits are attributed to polyphenol-rich pomegranate, little is known about its interaction with BaP. This study integrates histochemical, microbiomic, and metabolomic approaches to investigate the protective effects of pomegranate juice from BaP-induced pathologies. To this end, 48 Sprague-Dawley rats received, for four weeks, either pomegranate, BaP, both, or neither (n = 12 rats per group). Whereas histochemical examination of the colon indicated tissue damage marked by mucin depletion in BaP-fed animals, which was partially restored by administration of pomegranate juice, the fecal microbiome and metabolome retained their resilience, except for key changes related to pomegranate and BaP biotransformation. Meanwhile, dramatic microbiome restructuring and metabolome shift were observed as a consequence of the elapsed time (age factor). Additionally, the analysis allowed a thorough examination of fecal microbiome-metabolome associations, which delineated six microbiome clusters (marked by a differential abundance of Lactobacillaceae and Prevotellaceae, Rumincococcaceae, and Erysipelotrichaceae) and two major metabolome clusters (a sugar- and amino-acids-dominated metabotype vs. a cluster of fatty acids and hydrocarbons), with sugar alcohols maintaining a unique signature. In conclusion, using paired comparisons to minimize inter-individual animal variations allowed the dissection of temporal vs. treatment-derived variations. Microbiome-metabolome association clusters may be further exploited for metabotype prediction and gut-health biomarker discovery.
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Affiliation(s)
- Heba Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
- Center for Genome and Microbiome Research, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
| | - Shahira A ElBanna
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
- Center for Genome and Microbiome Research, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
| | - Rania A Khattab
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
| | - Mohamed A Farag
- Department of Pharmacognosy, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
| | - Aymen S Yassin
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
- Center for Genome and Microbiome Research, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
| | - Ramy K Aziz
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
- Center for Genome and Microbiome Research, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
- Microbiology and Immunology Research Program, Children's Cancer Hospital Egypt 57357, Cairo 11617, Egypt
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Cheng T, Lam AK, Gopalan V. Diet derived polycyclic aromatic hydrocarbons and its pathogenic roles in colorectal carcinogenesis. Crit Rev Oncol Hematol 2021; 168:103522. [PMID: 34748942 DOI: 10.1016/j.critrevonc.2021.103522] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 12/11/2022] Open
Abstract
Polycyclic aromatic hydrocarbon (PAHs) are molecules that contaminate meat products during the high-temperature cooking of meat. This study reviewed the pathogenic roles of meat derived polycyclic aromatic hydrocarbons in the carcinogenesis of colorectal cancer (CRC). Ingested PAHs undergo xenobiotic metabolism resulting in the activation of genotoxic metabolites that can induce DNA damage in the colorectum. Genetic polymorphisms in PAH xenobiotic enzymes are linked to the risk of CRC and suggest a role for PAH-meat ingestion in carcinogenesis of colorectal malignancies. Furthermore, PAH specific DNA adducts have been identified in colorectal cancer tissue and linked to high meat intake. DNA adduct resolution is mediated by the nucleotide excision repair, and polymorphisms within genes of this repair pathway and high meat intake are associated with increased CRC risk. In the literature, there is evidence from metabolic enzyme gene variants, DNA repair genes, PAH metabolites, and epidemiological studies suggesting PAH involvement in CRC.
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Affiliation(s)
- Tracie Cheng
- Cancer Molecular Pathology, School of Medicine & Dentistry, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Alfred K Lam
- Cancer Molecular Pathology, School of Medicine & Dentistry, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Vinod Gopalan
- Cancer Molecular Pathology, School of Medicine & Dentistry, Griffith University, Gold Coast, Queensland 4222, Australia.
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Budiatin AS, Sagitaras IB, Nurhayati IP, Khairah N, Nisak K, Susilo I, Khotib J. Attenuation of hyperplasia in lung parenchymal and colonic epithelial cells in DMBA-induced cancer by administering Andrographis paniculata Nees extract using animal model. J Basic Clin Physiol Pharmacol 2021; 32:497-504. [PMID: 34214295 DOI: 10.1515/jbcpp-2020-0440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 03/07/2021] [Indexed: 06/13/2023]
Abstract
OBJECTIVES This study was designed to evaluate the potential of Andrographis paniculata ethanolic extract to inhibit the increase in proliferation and induction of abnormal cell death. METHODS The hyperplasia stage as an early stage of cancer development was induced by oral administration of 20 mg/Kg BW DMBA to SD rats twice a week for 5 weeks. There were five groups in this study include negative control, positive control, and treatment groups of DMBA induction followed by administration of A. paniculata ethanolic extract in doses equivalent to 10, 30 or 100 mg/Kg BW andrographolide once per day for 6 consecutive weeks. On the last day, rats were sacrificed, lung and colon tissues were collected. Histological examination by HE staining and immunohistochemistry using p53, telomerase, and caspase-3 antibodies were aimed at observing hyperplasia state in these tissues. RESULTS DMBA induction to SD rats was able to produce hyperplasia in lung parenchymal and colon epithelial tissue. This can be showed by the increasing number of proliferated cells and as indicated by the number of brown-colored nuclei with sharper intensity. As well telomerase appears to be overexpressed strongly, while p53 and caspase-3 show low intensity. The administration of A. paniculata extract for 6 weeks showed a decrease in the number of cells that actively proliferate, a decrease in telomerase activity, and an increase in caspase-3 levels which indicate cellular death activity. CONCLUSIONS A. paniculata ethanolic extract can inhibit the development of cancer at the hyperplasia stage by reducing telomerase activity and increasing apoptosis, marked by an increase of caspase-3 expressions.
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Affiliation(s)
- Aniek Setiya Budiatin
- Department of Clinical Pharmacy, Faculty of Pharmacy, Airlangga University, Surabaya, East Java, Indonesia
| | - Ilham Bagus Sagitaras
- Department of Clinical Pharmacy, Faculty of Pharmacy, Airlangga University, Surabaya, East Java, Indonesia
| | - Ika Putri Nurhayati
- Department of Clinical Pharmacy, Faculty of Pharmacy, Airlangga University, Surabaya, East Java, Indonesia
| | - Nismatun Khairah
- Department of Clinical Pharmacy, Faculty of Pharmacy, Airlangga University, Surabaya, East Java, Indonesia
| | - Khoirotin Nisak
- Department of Clinical Pharmacy, Faculty of Pharmacy, Airlangga University, Surabaya, East Java, Indonesia
| | - Imam Susilo
- Department of Pathological Anatomy, Faculty of Medicine, Airlangga University, Surabaya, East Java, Indonesia
| | - Junaidi Khotib
- Department of Clinical Pharmacy, Faculty of Pharmacy, Airlangga University, Surabaya, East Java, Indonesia
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Molecular Aspects of Colorectal Adenomas: The Interplay among Microenvironment, Oxidative Stress, and Predisposition. BIOMED RESEARCH INTERNATIONAL 2020; 2020:1726309. [PMID: 32258104 PMCID: PMC7102468 DOI: 10.1155/2020/1726309] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 12/23/2019] [Accepted: 12/30/2019] [Indexed: 12/11/2022]
Abstract
The development of colorectal cancer (CRC) is a multistep process initiated by a benign polyp that has the potential to evolve into in situ carcinoma through the interactions between environmental and genetic factors. CRC incidence rates are constantly increased for young adult patients presenting an advanced tumor stage. The majority of CRCs arise from colonic adenomas originating from aberrant cell proliferation of colon epithelium. Endoscopic polypectomy represents a tool for early detection and removal of polyps, although the occurrence of cancers after negative colonoscopy shows a significant incidence. It has long been recognized that the aberrant regulation of Wingless/It (Wnt)/β-Catenin signaling in the pathogenesis of colorectal cancer is supported by its critical role in the differentiation of stem cells in intestinal crypts and in the maintenance of intestinal homeostasis. For this review, we will focus on the development of adenomatous polyps through the interplay between renewal signaling in the colon epithelium and reactive oxygen species (ROS) production. The current knowledge of molecular pathology allows us to deepen the relationships between oxidative stress and other risk factors as lifestyle, microbiota, and predisposition. We underline that the chronic inflammation and ROS production in the colon epithelium can impair the Wnt/β-catenin and/or base excision repair (BER) pathways and predispose to polyp development. In fact, the coexistence of oxidative DNA damage and errors in DNA polymerase can foster C>T transitions in various types of cancer and adenomas, leading to a hypermutated phenotype of tumor cells. Moreover, the function of Adenomatous Polyposis Coli (APC) protein in regulating DNA repair is very important as therapeutic implication making DNA damaging chemotherapeutic agents more effective in CRC cells that tend to accumulate mutations. Additional studies will determine whether approaches based on Wnt inhibition would provide long-term therapeutic value in CRC, but it is clear that APC disruption plays a central role in driving and maintaining tumorigenesis.
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Isoorientin attenuates benzo[a]pyrene-induced colonic injury and gut microbiota disorders in mice. Food Res Int 2019; 126:108599. [DOI: 10.1016/j.foodres.2019.108599] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 07/18/2019] [Accepted: 07/30/2019] [Indexed: 12/19/2022]
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Smith J, Neupane R, McAmis W, Singh U, Chatterjee S, Raychoudhury S. Toxicity of polycyclic aromatic hydrocarbons involves NOX2 activation. Toxicol Rep 2019; 6:1176-1181. [PMID: 31763181 PMCID: PMC6861563 DOI: 10.1016/j.toxrep.2019.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 10/31/2019] [Accepted: 11/04/2019] [Indexed: 12/21/2022] Open
Abstract
PAHs cause decrease in cell viability and increase in lactate levels. The mixture of PAHs suppress S phase. Toxicity is accompanied by NOX2 activation.
Polycyclic Aromatic Hydrocarbons (PAHs) are environmental pollutants. The present study compares the toxic effects of BaP alone and a mixture of PAHs on human breast cancer cells. We hypothesize that PAH mixture is more toxic than BaP alone, and an increased NOX2 activation is related to PAH-induced oxidative stress. Initially, we exposed cultured human breast cancer cells to BaP alone (125 ng/mL and 500 ng/mL) and a mixture of PAHs (125 ng/mL and 500 ng/mL). After 24 h of exposure, the PAH mixture demonstrated a significant (P < 0.05) reduction in cell viability. The higher concentration of BaP alone (500 ng/mL) and both 125 ng/mL and 500 ng/mL PAH mixture significantly (P < 0.05) increased lactate production by MDA-MB-231 cells. We had observed an identical level of increased lactate levels when the cells were exposed to PAHs for 48 h. Flow cytometric analysis revealed that only PAHs mixture (both 125 ng/mL and 500 ng/mL) suppressed S phase significantly (P < 0.05). Finally, immunofluorescence microscopy was undertaken to examine the role of NOX2 due to PAHs toxicity. Colocalization of GP91phox and P47phox, a hallmark of NOX2 activation in the cell membrane of macrophage Kupffer cells demonstrated that higher concentration of BaP or PAH mixture showed increased colocalization events. These data suggest that the mixture of PAHs is more toxic and perturbing to DNA synthesis than BaP alone in cultured cells, and the toxicity is accompanied by NOX2 activation. Thus PAHs can lead to the increased burden of oxidative stress and alter the cellular redox status.
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Affiliation(s)
- Joycelyn Smith
- Department of Biology, Chemistry, and Environmental Health Science, Benedict College, 1600 Harden Street, Columbia, SC, 29204, USA
| | - Rajendra Neupane
- Department of Biology, Chemistry, and Environmental Health Science, Benedict College, 1600 Harden Street, Columbia, SC, 29204, USA
| | - William McAmis
- Department of Biology, Chemistry, and Environmental Health Science, Benedict College, 1600 Harden Street, Columbia, SC, 29204, USA
| | - Udai Singh
- School of Medicine, University of South Carolina, Columbia, SC, USA
| | - Saurabh Chatterjee
- Environmental Health and Disease Laboratory, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
| | - Samir Raychoudhury
- Department of Biology, Chemistry, and Environmental Health Science, Benedict College, 1600 Harden Street, Columbia, SC, 29204, USA
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8
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Huderson AC, Rekha Devi PV, Niaz MS, Adunyah SE, Ramesh A. Alteration of benzo(a)pyrene biotransformation by resveratrol in Apc Min/+ mouse model of colon carcinogenesis. Invest New Drugs 2018; 37:238-251. [PMID: 29931584 DOI: 10.1007/s10637-018-0622-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/11/2018] [Indexed: 12/30/2022]
Abstract
Epidemiological surveys have revealed that environmental and dietary factors contribute to most of the human cancers. Our earlier studies have shown that resveratrol (RVT), a phytochemical reduced the tumor number, size and incidence of dysplasias induced by benzo(a)pyrene (BaP), an environmental toxicant in the ApcMin/+ mouse model of colon cancer. In this study we investigated to ascertain whether the preventive effects of RVT on BaP-induced colon carcinogenesis is a result of altered BaP biotransformation by RVT. For the first group of mice, 100 μg BaP/kg bw was administered in peanut oil via oral gavage over a 60 day period. For the second group, 45 μg RVT/kg bw was co-administered with BaP. For the third group, RVT was administered for 1 week prior to BaP exposure. Blood, colon and liver were collected from control and BaP/RVT-treated mice at 60 days post-BaP & RVT exposure. We have assayed activities and expression (protein & mRNA) of drug metabolizing enzymes such as cytochrome P4501A1 (CYP1A1), CYP1B1, and glutathione-S-transferase (GST) in colon and liver samples from the treatment groups mentioned above. An increased expression of CYP1A1 in liver and colon and of CYP1B1 in liver of BaP-treated mice was seen, while RVT inhibited the extent of biotransformation mediated by these enzymes in the respective tissue samples. In the case of GST, an increased expression in colon of BaP alone-treated mice was noted when RVT was administered prior to BaP or simultaneously with BaP. However, there is no change in liver GST expression between BaP and RVT treatment groups. The concentrations of BaP aqueous (phase II) metabolites were found to be greater than the organic (phase I) metabolites, suggesting that RVT slows down the phase I metabolism (metabolic activation) of BaP, while enhancing phase II metabolism (detoxification). Additionally, the BaP-DNA adduct concentrations measured in colon and liver of BaP + RVT-treated mice were low relative to their BaP counterparts. Taken together, our findings strongly suggest that RVT alleviates BaP-induced colon carcinogenesis by impairing biotransformation pathways and DNA adduct formation, and therefore holds promise as a chemopreventive agent.
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Affiliation(s)
- Ashley C Huderson
- The American Society of Mechanical Engineers, 1828 L St. N.W, Washington, DC, 20036, USA
| | - P V Rekha Devi
- Toxicology and Pharmacology Unit, Biology Division, Indian Institute of Chemical Technology, Hyderabad, Telangana, 500007, India
| | - Mohammad S Niaz
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd, Nashville, TN, 37208, USA
| | - Samuel E Adunyah
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd, Nashville, TN, 37208, USA
| | - Aramandla Ramesh
- Department of Biochemistry, Cancer Biology, Neuroscience & Pharmacology, Meharry Medical College, 1005 D.B. Todd Blvd, Nashville, TN, 37208, USA.
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Guan F, Tabrizian T, Novaj A, Nakanishi M, Rosenberg DW, Huffman DM. Dietary Walnuts Protect Against Obesity-Driven Intestinal Stem Cell Decline and Tumorigenesis. Front Nutr 2018; 5:37. [PMID: 29904634 PMCID: PMC5990619 DOI: 10.3389/fnut.2018.00037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/23/2018] [Indexed: 12/12/2022] Open
Abstract
Obesity can negatively impact intestinal homeostasis, and increase colon cancer risk and related mortality. Thus, given the alarmingly high rates of obesity in the US and globally, it is critical to identify practical strategies that can break the obesity-cancer link. Walnuts have been increasingly recognized to mitigate cancer risk, and contain many bioactive constituents with antioxidant and anti-inflammatory properties that could potentially counteract pathways thought to be initiators of obesity-related cancer. Therefore, the purpose of this study was to determine if walnuts could preserve intestinal homeostasis, and attenuate tumorigenesis and growth in the context of obesity and a high calorie diet. To this end, we studied effects of walnuts on these parameters under different dietary conditions in wildtype mice, two independent Apc models (Apc1638N/+ and ApcΔ14), and in MC38 colon cancer cells in vivo, respectively. Walnuts did not alter the metabolic phenotype or intestinal morphology in normal mice fed either a low-fat diet (LFD), LFD with 6% walnuts (LFD+W), high-fat diet (HFD), or HFD with 7.6% walnuts (HFD+W). However, walnuts did lead to a significant reduction in circulating CCL5 and preserved intestinal stem cell (ISC) function under HFD-fed conditions. Furthermore, walnuts reduced tumor multiplicity in Apc1638N/+ male HFD+W animals, as compared to HFD controls (3.7 ± 0.5 vs. 2.5 ± 0.3; P = 0.015), tended to reduce the number of adenocarcinomas (0.67 ± 0.16 vs. 0.29 ± 0.12; P = 0.07), and preferentially limited tumor growth in ApcΔ14 male mice (P = 0.019) fed a high-calorie western-style diet. In summary, these data demonstrate that walnuts confer significant protection against intestinal tumorigenesis and growth and preserve ISC function in the context of a high-calorie diet and obesity. Thus, these data add to the accumulating evidence connecting walnuts as a potentially effective dietary strategy to break the obesity-colon cancer link.
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Affiliation(s)
- Fangxia Guan
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States.,Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, United States.,School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Tahmineh Tabrizian
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States.,Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Ardijana Novaj
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States.,Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Masako Nakanishi
- School of Medicine, University of Connecticut Health, Farmington, CT, United States
| | - Daniel W Rosenberg
- School of Medicine, University of Connecticut Health, Farmington, CT, United States
| | - Derek M Huffman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States.,Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, United States.,Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, United States
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Fernández J, García L, Monte J, Villar CJ, Lombó F. Functional Anthocyanin-Rich Sausages Diminish Colorectal Cancer in an Animal Model and Reduce Pro-Inflammatory Bacteria in the Intestinal Microbiota. Genes (Basel) 2018; 9:E133. [PMID: 29494510 PMCID: PMC5867854 DOI: 10.3390/genes9030133] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/18/2018] [Accepted: 02/23/2018] [Indexed: 12/12/2022] Open
Abstract
Colorectal cancer is the fourth most common neoplasia in Europe, where it accounts for 28.2 new cases per 100,000 inhabitants. In an effort to decrease the incidence of this disease, various prevention measures are being studied, one of which are anthocyanin-rich foods. Anthocyanins are potent antioxidant flavonoids mainly found in flowers and colorful fruits and vegetables. These nutraceuticals have diverse biological functions once ingested, including immunomodulatory, anti-inflammatory and antitumor functions. In order to test the preventive effect of these flavonoids against colorectal cancer, an animal model (Rattus norvegicus F344) was developed. In this model two doses of azoxymethane (10 mg/kg) and two treatments with dextran sodium sulfate (DSS) were administered to the animals. For 20 weeks they were fed either control rat feed, control sausages, or functional sausages containing 0.1% (w/w) of anthocyanins from a mixture of dehydrated blackberries and strawberries. At the end of that period, the animals were sacrificed and their antioxidant plasma levels and digestive tract tissues were analyzed. The results revealed a statistically significant reduction in the number of colon tumors in the functional sausages cohort with respect to the control animals and an increase in the FRAP (ferric reducing ability of plasma) total antioxidant activity in that same cohort. Colon microbiota differences were also examined via metagenomics 16S ribosomal RNA (rRNA) sequencing, revealing a significant reduction in populations of the pro-inflammatory Bilophila wadsworthia. Therefore, the design of functional processed meat products, such as ones enriched with anthocyanins, may be an effective strategy for preventing inflammatory digestive diseases and colorectal cancer in human populations.
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Affiliation(s)
- Javier Fernández
- Research Unit "Biotechnology in Nutraceuticals and Bioactive Compounds-BIONUC", Departamento de Biología Funcional, Área de Microbiología, Universidad de Oviedo. C/Julián Clavería, 7, 33006 Oviedo, Spain.
- IUOPA (Instituto Universitario de Oncología del Principado de Asturias), C/Fernando Bongera, Edificio Santiago Gascón, 1, 33006 Oviedo, Spain.
- ISPA (Instituto de Investigación Sanitaria del Principado de Asturias), C/Aldea Cerdeño, 33011 Oviedo, Spain.
| | - Lorena García
- El Hórreo Healthy Foods SL, Polígono de Granda 17, 33199 Siero, Spain.
| | - Joaquín Monte
- El Hórreo Healthy Foods SL, Polígono de Granda 17, 33199 Siero, Spain.
| | - Claudio J Villar
- Research Unit "Biotechnology in Nutraceuticals and Bioactive Compounds-BIONUC", Departamento de Biología Funcional, Área de Microbiología, Universidad de Oviedo. C/Julián Clavería, 7, 33006 Oviedo, Spain.
- IUOPA (Instituto Universitario de Oncología del Principado de Asturias), C/Fernando Bongera, Edificio Santiago Gascón, 1, 33006 Oviedo, Spain.
- ISPA (Instituto de Investigación Sanitaria del Principado de Asturias), C/Aldea Cerdeño, 33011 Oviedo, Spain.
| | - Felipe Lombó
- Research Unit "Biotechnology in Nutraceuticals and Bioactive Compounds-BIONUC", Departamento de Biología Funcional, Área de Microbiología, Universidad de Oviedo. C/Julián Clavería, 7, 33006 Oviedo, Spain.
- IUOPA (Instituto Universitario de Oncología del Principado de Asturias), C/Fernando Bongera, Edificio Santiago Gascón, 1, 33006 Oviedo, Spain.
- ISPA (Instituto de Investigación Sanitaria del Principado de Asturias), C/Aldea Cerdeño, 33011 Oviedo, Spain.
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11
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Harris KL, Pulliam SR, Okoro E, Guo Z, Washington MK, Adunyah SE, Amos-Landgraf JM, Ramesh A. Western diet enhances benzo(a)pyrene-induced colon tumorigenesis in a polyposis in rat coli (PIRC) rat model of colon cancer. Oncotarget 2018; 7:28947-60. [PMID: 26959117 PMCID: PMC5045369 DOI: 10.18632/oncotarget.7901] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 02/15/2016] [Indexed: 12/13/2022] Open
Abstract
Consumption of Western diet (WD), contaminated with environmental toxicants, has been implicated as one of the risk factors for sporadic colon cancer. Our earlier studies using a mouse model revealed that compared to unsaturated dietary fat, the saturated dietary fat exacerbated the development of colon tumors caused by B(a)P. The objective of this study was to study how WD potentiates B(a)P-induced colon carcinogenesis in the adult male rats that carry a mutation in the Apc locus - the polyposis in the rat colon (PIRC) rats. Groups of PIRC rats were fed with AIN-76A standard diet (RD) or Western diet (WD) and received 25, 50, or 100 μg B(a)P/kg body weight (wt) via oral gavage for 60 days. Subsequent to exposure, rats were euthanized; colons were retrieved and preserved in 10% formalin for counting the polyp numbers, measuring the polyp size, and histological analyses. Blood samples were collected and concentrations of cholesterol, triglycerides, glucose, insulin and leptin were measured. Rats that received WD + B(a)P showed increased levels of cholesterol, triglycerides, and leptin in comparison to RD + B(a)P groups or controls. The colon tumor numbers showed a B(a)P dose-response relationship. Adenomas with high grade dysplasia were prominent in B(a)P + WD rats compared to B(a)P + RD rats and controls (p < 0.05). The larger rat model system used in this study allows for studying more advanced tumor phenotypes over a longer duration and delineating the role of diet - toxicant interactions in sporadic colon tumor development.
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Affiliation(s)
- Kelly L Harris
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - Stephanie R Pulliam
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - Emmanuel Okoro
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, USA
| | - Zhongmao Guo
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, USA
| | - Mary K Washington
- Department of Pathology, Vanderbilt University, Nashville, TN 37232, USA
| | - Samuel E Adunyah
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208, USA
| | - James M Amos-Landgraf
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
| | - Aramandla Ramesh
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208, USA
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Hoffman JB, Petriello MC, Hennig B. Impact of nutrition on pollutant toxicity: an update with new insights into epigenetic regulation. REVIEWS ON ENVIRONMENTAL HEALTH 2017; 32:65-72. [PMID: 28076319 PMCID: PMC5489226 DOI: 10.1515/reveh-2016-0041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/09/2016] [Indexed: 05/03/2023]
Abstract
Exposure to environmental pollutants is a global health problem and is associated with the development of many chronic diseases, including cardiovascular disease, diabetes and metabolic syndrome. There is a growing body of evidence that nutrition can both positively and negatively modulate the toxic effects of pollutant exposure. Diets high in proinflammatory fats, such as linoleic acid, can exacerbate pollutant toxicity, whereas diets rich in bioactive and anti-inflammatory food components, including omega-3 fatty acids and polyphenols, can attenuate toxicant-associated inflammation. Previously, researchers have elucidated direct mechanisms of nutritional modulation, including alteration of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, but recently, increased focus has been given to the ways in which nutrition and pollutants affect epigenetics. Nutrition has been demonstrated to modulate epigenetic markers that have been linked either to increased disease risks or to protection against diseases. Overnutrition (i.e. obesity) and undernutrition (i.e. famine) have been observed to alter prenatal epigenetic tags that may increase the risk of offspring developing disease later in life. Conversely, bioactive food components, including curcumin, have been shown to alter epigenetic markers that suppress the activation of NF-κB, thus reducing inflammatory responses. Exposure to pollutants also alters epigenetic markers and may contribute to inflammation and disease. It has been demonstrated that pollutants, via epigenetic modulations, can increase the activation of NF-κB and upregulate microRNAs associated with inflammation, cardiac injury and oxidative damage. Importantly, recent evidence suggests that nutritional components, including epigallocatechin gallate (EGCG), can protect against pollutant-induced inflammation through epigenetic regulation of proinflammatory target genes of NF-κB. Further research is needed to better understand how nutrition can modulate pollutant toxicity through epigenetic regulation. Therefore, the objective of this review is to elucidate the current evidence linking epigenetic changes to pollutant-induced diseases and how this regulation may be modulated by nutrients allowing for the development of future personalized lifestyle interventions.
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Affiliation(s)
- Jessie B Hoffman
- Superfund Research Center, University of Kentucky, Lexington, KY 40536
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Michael C Petriello
- Superfund Research Center, University of Kentucky, Lexington, KY 40536
- Department of Animal and Food Sciences, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40536
| | - Bernhard Hennig
- Superfund Research Center, University of Kentucky, Lexington, KY 40536
- Department of Animal and Food Sciences, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40536
- Correspondence should be directed to: Bernhard Hennig, 900 S. Limestone Street, Superfund Research Center, University of Kentucky, Lexington, KY 40536, USA. Tel.: +1 859-218-1343; fax: +1 859-257-1811;
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13
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Khaniyan M, Salamat N, Safahieh A, Movahedinia A. Detection of benzo[a]pyrene-induced immunotoxicity in orange spotted grouper (Epinephelus coioides). ENVIRONMENTAL TOXICOLOGY 2016; 31:329-338. [PMID: 25263604 DOI: 10.1002/tox.22047] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 09/02/2014] [Accepted: 09/04/2014] [Indexed: 06/03/2023]
Abstract
This study aimed to investigate the effects of benzo[a]pyrene (BaP) on immune status of orange spotted grouper (Epinephelus coioides). Fish were injected with 2, 20 and 35 mg/kg-bw of BaP and were kept under laboratory conditions for 14 days. Blood samples were taken at days 1, 4, 7, and 14 and changes in total WBC and RBC, phagocytosis, lysozyme activity, lysosomal membrane stability, immunoglobulin M (IgM) level and antibacterial activity were evaluated. Also BaP bioaccumulation in fish muscle was measured. BaP concentration in the muscle of treated fish reached a maximum level after 4 days (P < 0.05). Exposure of fish to BaP resulted in a significant decrease of total RBC and WBC, lysozyme activity, lysosomal membrane stability, IgM level and antibacterial activity after 4 days and phagocytosis after 7 days of the experiment (P < 0.05). Totally, the results revealed BaP ability to suppress the fish immune function.
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Affiliation(s)
- Maryam Khaniyan
- Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, P.O. Box 669, Khorramshahr, Iran
| | - Negin Salamat
- Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, P.O. Box 669, Khorramshahr, Iran
| | - Alireza Safahieh
- Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, P.O. Box 669, Khorramshahr, Iran
| | - Abdolali Movahedinia
- Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, P.O. Box 669, Khorramshahr, Iran
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Banks LD, Amoah P, Niaz MS, Washington MK, Adunyah SE, Ramesh A. Olive oil prevents benzo(a)pyrene [B(a)P]-induced colon carcinogenesis through altered B(a)P metabolism and decreased oxidative damage in Apc(Min) mouse model. J Nutr Biochem 2015; 28:37-50. [PMID: 26878781 DOI: 10.1016/j.jnutbio.2015.09.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 09/17/2015] [Accepted: 09/23/2015] [Indexed: 02/07/2023]
Abstract
Colon cancer ranks third in cancer-related mortalities in the United States. Many studies have investigated factors that contribute to colon cancer in which dietary and environmental factors have been shown to play an integral role in the etiology of this disease. Specifically, human dietary intake of environmental carcinogens such as polycyclic aromatic hydrocarbons has generated interest in looking at how it exerts its effects in gastrointestinal carcinogenesis. Therefore, the objective of this study was to investigate the preventative effects of olive oil on benzo(a)pyrene [B(a)P]-induced colon carcinogenesis in adult Apc(Min) mice. Mice were assigned to a control (n=8) or treatment group (n=8) consisting of 25, 50 and 100-μg B(a)P/kg body weight (bw) dissolved in tricaprylin [B(a)P-only group] or olive oil daily via oral gavage for 60 days. Our studies showed that Apc(Min) mice exposed to B(a)P developed a significantly higher number (P<0.05) of larger dysplastic adenomas compared to those exposed to B(a)P + olive oil. Treatment of mice with B(a)P and olive oil significantly altered (P<0.05) the expression of drug-metabolizing enzymes in both the colon and liver tissues. However, only GST activity was significantly higher (P<0.05) in the liver of mice treated with 50- and 100-μg B(a)P/kg bw + olive oil. Lastly, olive oil promoted rapid detoxification of B(a)P by decreasing its organic metabolite concentrations and also decreasing the extent of DNA damage to colon and liver tissues (P<0.05). These results suggest that olive oil has a protective effect against B(a)P-induced colon tumors.
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Affiliation(s)
- Leah D Banks
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN, 37208
| | - Priscilla Amoah
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN, 37208
| | - Mohammad S Niaz
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN, 37208
| | - Mary K Washington
- Department of Pathology, Vanderbilt University Medical Center, Nashville, TN, 37232
| | - Samuel E Adunyah
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN, 37208
| | - Aramandla Ramesh
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN, 37208.
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15
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Koyama N, Hakura A, Toritsuka N, Sonoda J, Seki Y, Tohyama O, Asakura S, Nakano-Ito K, Hosokawa S. Wif1 and Ifitm3 gene expression preferentially altered in the colon mucosa of benzo[a]pyrene pre-treated mice following exposure to dextran sulfate sodium. Chem Biol Interact 2015; 240:164-70. [PMID: 26271895 DOI: 10.1016/j.cbi.2015.07.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 07/01/2015] [Accepted: 07/24/2015] [Indexed: 12/17/2022]
Abstract
Benzo[a]pyrene (BP) is highly mutagenic and yet does not lead to tumor development in the murine colon. We recently reported the generation of colonic tumors one week after treatment with BP followed by dextran sulfate sodium (DSS), a colitis-inducer. In this BP/DSS model, male CD2F1 mice were treated orally with BP at 125 mg/kg/day for 5 days, followed by 4% DSS in drinking water for one week. There has been no report so far on the molecular mechanisms involved in tumor development in this model. In the present study, we performed global gene expression analysis on the colonic mucosae obtained from BP-exposed mice one week after treatment with DSS and those treated with the vehicle, BP, or DSS alone. Global gene expression analysis revealed that there were 563 genes preferentially altered (≥2-fold vs vehicle group) in the colonic mucosae exposed to both BP and DSS. Furthermore, comparative gene expression analysis combined with Ingenuity Pathway Analysis™ identified 2 genes associated with Wnt/β-catenin signaling pathway that were preferentially up-regulated (≥2-fold vs vehicle group) when BP and DSS were treated in combination in the distal part (site of predilection for tumor induction) of the colonic mucosae, especially in colonic tumors: WNT inhibitory factor 1 (Wif1; 14.6-fold increase) and interferon induced membrane protein 3 (Ifitm3; 5.7-fold increase). In colonic tumors, expression of Wif1 and Ifitm3 proteins were both confirmed by western blot analysis. These findings suggest that these genes are associated with rapid induction of colonic tumors in mice after exposure to BP/DSS, providing insights into the mechanisms of the BP/DSS short-term colon carcinogenesis.
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Affiliation(s)
- Naoki Koyama
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan.
| | - Atsushi Hakura
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Naoki Toritsuka
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Jiro Sonoda
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Yuki Seki
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Osamu Tohyama
- Biomarkers and Personalized Medicine Core Function Unit, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Shoji Asakura
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Kyoko Nakano-Ito
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Satoru Hosokawa
- Tsukuba Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
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Sonoda J, Seki Y, Hakura A, Hosokawa S. Time course of the incidence/multiplicity and histopathological features of murine colonic dysplasia, adenoma and adenocarcinoma induced by benzo[a]pyrene and dextran sulfate sodium. J Toxicol Pathol 2015; 28:109-20. [PMID: 26028820 PMCID: PMC4444509 DOI: 10.1293/tox.2014-0061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 02/05/2015] [Indexed: 12/29/2022] Open
Abstract
Benzo[a]pyrene (BP) is mutagenic but noncarcinogenic in the murine colon. Recently, we reported rapid induction of colonic tumors by treatment of CD2F1 mice with BP (125 mg/kg for 5 days) followed by a colitis inducer, dextran sulfate sodium (DSS) (4% in drinking water for 1 or 2 weeks). However, there are no reports on detailed time course and histopathological features of colonic proliferative lesions in this model. Here, we show the detailed time course of colonic dysplasia, adenoma and adenocarcinoma induced by treatment with BP, DSS, and a combination of the two (BP/DSS). In the colon of mice exposed to BP/DSS, 14.6 dysplastic foci per mouse were present one week after DSS treatment (week 4). The number of dysplastic foci decreased with time to 3.1 at week 9 and thereafter remained almost constant. At week 4, 1.5 adenocarcinomas were also observed, with a marked increase in numbers with time, reaching 29.3 at week 14. In contrast, the number of dysplastic foci induced by DSS alone showed a time course similar to that following BP/DSS treatment; however, only a few tumors appeared. Neither dysplastic foci nor neoplastic lesions were induced by BP only. In mice exposed to BP/DSS, β-catenin was demonstrated immunohistochemically in the nucleus and/or cytoplasm of the tumor cells, and this translocation from the cell membrane was evident in subsets of dysplastic foci. In dysplastic foci induced by DSS alone, β-catenin was absent in the nucleus/cytoplasm. These finding suggest that aberrant β-catenin accumulation in dysplastic foci is associated with tumor progression in this BP/DSS model.
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Affiliation(s)
- Jiro Sonoda
- Tsukuba Drug Safety, Global Drug Safety, Biopharmaceutical Assessments Core Function Unit, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
| | - Yuki Seki
- Tsukuba Drug Safety, Global Drug Safety, Biopharmaceutical Assessments Core Function Unit, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
| | - Atsushi Hakura
- Tsukuba Drug Safety, Global Drug Safety, Biopharmaceutical Assessments Core Function Unit, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
| | - Satoru Hosokawa
- Tsukuba Drug Safety, Global Drug Safety, Biopharmaceutical Assessments Core Function Unit, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
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17
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Mantey JA, Rekhadevi PV, Diggs DL, Ramesh A. Metabolism of benzo(a)pyrene by subcellular fractions of gastrointestinal (GI) tract and liver in Apc Min mouse model of colon cancer. Tumour Biol 2014; 35:4929-35. [DOI: 10.1007/s13277-014-1647-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 01/12/2014] [Indexed: 12/19/2022] Open
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18
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Diggs DL, Myers JN, Banks LD, Niaz MS, Hood DB, Roberts LJ, Ramesh A. Influence of dietary fat type on benzo(a)pyrene [B(a)P] biotransformation in a B(a)P-induced mouse model of colon cancer. J Nutr Biochem 2013; 24:2051-63. [PMID: 24231098 PMCID: PMC3904801 DOI: 10.1016/j.jnutbio.2013.07.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 07/06/2013] [Accepted: 07/17/2013] [Indexed: 02/06/2023]
Abstract
In the US alone, around 60,000 lives/year are lost due to colon cancer. Diet and environment have been implicated in the development of sporadic colon tumors. The objective of this study was to determine how dietary fat potentiates the development of colon tumors through altered B(a)P biotransformation, using the Adenomatous polyposis coli with Multiple intestinal neoplasia mouse model. Benzo(a)pyrene was administered to mice through tricaprylin, and unsaturated (USF; peanut oil) and saturated (SF; coconut oil) fats at doses of 50 and 100 μg/kg via oral gavage over a 60-day period. Blood, colon, and liver were collected at the end of exposure period. The expression of B(a)P biotransformation enzymes [cytochrome P450 (CYP)1A1, CYP1B1 and glutathione-S-transferase] in liver and colon were assayed at the level of protein, mRNA and activities. Plasma and tissue samples were analyzed by reverse phase high-performance liquid chromatography for B(a)P metabolites. Additionally, DNA isolated from colon and liver tissues was analyzed for B(a)P-induced DNA adducts by the (32)P-postlabeling method using a thin-layer chromatography system. Benzo(a)pyrene exposure through dietary fat altered its metabolic fate in a dose-dependent manner, with 100 μg/kg dose group registering an elevated expression of B(a)P biotransformation enzymes, and greater concentration of B(a)P metabolites, compared to the 50 μg/kg dose group (P<.05). This effect was more pronounced for SF group compared to USF group (P<.05). These findings establish that SF causes sustained induction of B(a)P biotransformation enzymes and extensive metabolism of this toxicant. As a consequence, B(a)P metabolites were generated to a greater extent in colon and liver, whose concentrations also registered a dose-dependent increase. These metabolites were found to bind with DNA and form B(a)P-DNA adducts, which may have contributed to colon tumors in a subchronic exposure regimen.
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Affiliation(s)
- Deacqunita L. Diggs
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208
| | - Jeremy N. Myers
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208
| | - Leah D. Banks
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208
| | - Mohammad S. Niaz
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208
| | - Darryl B. Hood
- Department of Neuroscience and Pharmacology, Meharry Medical College,Nashville, TN 37208
| | - L. Jackson Roberts
- Departments of Pharmacology and Medicine, Pathology, Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Aramandla Ramesh
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208
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Harris KL, Banks LD, Mantey JA, Huderson AC, Ramesh A. Bioaccessibility of polycyclic aromatic hydrocarbons: relevance to toxicity and carcinogenesis. Expert Opin Drug Metab Toxicol 2013; 9:1465-80. [PMID: 23898780 PMCID: PMC4081012 DOI: 10.1517/17425255.2013.823157] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Bioaccessibility is a growing area of research in the field of risk assessment. As polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants, they are the toxicants of focus to establish cancer risks in humans. Orally ingested PAHs also cause toxicity and even affect the pharmacokinetic behavior of some therapeutic agents. Toward this end, bioaccessibility is being used as a tool to assess the risk of PAHs via dietary exposures. AREAS COVERED This review covers some in vitro bioaccessibility models for PAHs that have been used for the past one-and-a-half decade. This review also considers the factors that influence bioaccessibility and debates the merits and limitations of using a bioaccessibility concept for estimating risk from ingestion of PAH-contaminated soil and food. Finally, the authors discuss the implications of bioaccessibility for PAH-induced toxicity and cancers in the context of risk assessment. EXPERT OPINION So far, much of the focus on PAH bioaccessibility is centered on soil as a preferential matrix. However, ingestion of PAHs through diet far exceeds the amount accidentally ingested through soil. Therefore, bioaccessibility could be exploited as a tool to assess the relative risk of various dietary ingredients tainted with PAHs. While bioaccessibility is a promising approach for assessing PAH risk arising from various types of contaminated soils, none of the models proposed appears to be valid. Bioaccessibility values, derived from in vitro studies, still require validation from in vivo studies.
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Affiliation(s)
- Kelly L Harris
- Meharry Medical College, Department of Biochemistry & Cancer Biology , 1005 D.B. Todd Blvd, Nashville, TN, 37208 , USA +1 615 327 6486 ; +1 615 327 6442 ;
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20
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Harris KL, Myers JN, Ramesh A. Benzo(a)pyrene modulates fluoranthene-induced cellular responses in HT-29 colon cells in a dual exposure system. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2013; 36:358-367. [PMID: 23732482 PMCID: PMC3826174 DOI: 10.1016/j.etap.2013.04.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/16/2013] [Accepted: 04/24/2013] [Indexed: 05/30/2023]
Abstract
Our environment is contaminated with a diverse array of chemicals; one of which is polycyclic aromatic hydrocarbons (PAHs). While some PAHs are potent by nature, others undergo interactions such as additivity, synergism, antagonism or potentiation to manifest their toxicity. Therefore, the objective of this study was to investigate whether exposure to benzo(a)pyrene (BaP), a PAH compound influences the cytotoxicity and metabolism of fluoranthene (FLA; another PAH compound) using HT-29 cells. Cells cultured in Dulbecco's Modified Eagle Medium were treated with 1, 5, 10, 25μM BaP and FLA (0.01% dimethylsulfoxide as vehicle) individually and in combination over the course of 0-96h. At the end of exposure, cells were stained with propidium iodide and the changes in cell cycle were analyzed using FACS analysis. Apoptosis was determined by caspase-3 assay. Post-incubation, samples were extracted and analyzed for FLA metabolites by reverse-phase HPLC with fluorescence detection. Cells exposed to BaP+FLA showed a marginal decrease in growth as compared to FLA alone and vehicle controls. Also, a decline in the percentage of cells in the S and G2 phases compared to G1 phase of cell cycle was noted when cells were treated with BaP and FLA together, compared to individual FLA treatment. The rate of FLA metabolism was more when cells were exposed to FLA in combination with BaP, compared to FLA alone. The enhanced biotransformation of FLA as a result of concomitant exposure to BaP may have implications for colon cancer risks arising from human dietary exposure to PAH mixtures through consumption of barbecued meat.
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Affiliation(s)
- Kelly L Harris
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Boulevard, Nashville, TN 37208, USA
| | - Jeremy N Myers
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Boulevard, Nashville, TN 37208, USA
| | - Aramandla Ramesh
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Boulevard, Nashville, TN 37208, USA.
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Huderson AC, Myers JN, Niaz MS, Washington MK, Ramesh A. Chemoprevention of benzo(a)pyrene-induced colon polyps in ApcMin mice by resveratrol. J Nutr Biochem 2012; 24:713-24. [PMID: 22889612 DOI: 10.1016/j.jnutbio.2012.04.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 03/31/2012] [Accepted: 04/04/2012] [Indexed: 02/06/2023]
Abstract
Human dietary exposure to benzo(a)pyrene (BaP) has generated interest with regard to the association of BaP with gastrointestinal carcinogenesis. Since colon cancer ranks third among cancer-related mortalities, it is necessary to evaluate the effect of phytochemicals on colon cancer initiation and progression. In this study, we investigated the preventive effects of resveratrol (RVT) on BaP-induced colon carcinogenesis in Apc(Min) mouse model. For the first group of mice, 100 μg BaP/kg body weight was administered to mice in peanut oil via oral gavage over a 60-day period. For the second group, RVT was coadministered with BaP at a dose of 45 μg/kg. For the third group, RVT was administered for 1 week prior to BaP exposure for 60 days. Jejunum, colon and liver were collected at 60 days post BaP and RVT exposure; adenomas in jejunum and colon were counted and subjected to histopathology. RVT reduced the number of colon adenomas in BaP+RVT-treated mice significantly compared to that in mice that received BaP alone. While dysplasia of varying degrees was noted in colon of BaP-treated mice, the dysplasias were of limited occurrence in RVT-treated mice. To ascertain whether the tumor inhibition is a result of altered BaP-induced toxicity of tumor cells, growth, apoptosis and proliferation of adenocarcinoma cells were assessed posttreatment with RVT and BaP. Cotreatment with RVT increased apoptosis and decreased cell proliferation to a greater extent than with BaP alone. Overall, our observations reveal that RVT inhibits colon tumorigenesis when given together with BaP and holds promise as a therapeutic agent.
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Affiliation(s)
- Ashley C Huderson
- Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, TN 37208, USA
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Diggs DL, Harris KL, Rekhadevi PV, Ramesh A. Tumor microsomal metabolism of the food toxicant, benzo(a)pyrene, in ApcMin mouse model of colon cancer. Tumour Biol 2012; 33:1255-60. [PMID: 22430258 DOI: 10.1007/s13277-012-0375-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Accepted: 03/05/2012] [Indexed: 12/22/2022] Open
Abstract
The present study was conducted to investigate whether colon tumors were capable of metabolizing benzo(a)pyrene (BaP), and fluoranthene (FLA), two toxicants that belong to the polycyclic aromatic hydrocarbon family of compounds. Microsomes were isolated from the colon tumors of Apc( Min ) mice that received subchronic doses of 50 μg/kg BaP and incubated with either BaP or FLA (3 μM each) alone or in combination and appropriate control groups that received nothing. Subsequent to incubation, samples were extracted with ethyl acetate and analyzed for BaP and FLA metabolites by reverse-phase HPLC equipped with fluorescence detection. Microsomes from tumor tissues were found to metabolize BaP to a greater extent than those from the non-tumor tissues. The rate of BaP metabolism (picomoles of metabolite per minute per milligram of protein) was found to be more when microsomes from BaP-pretreated mice were exposed to BaP alone and FLA in combination with BaP, compared to controls. The microsomes from BaP-preexposed mice generated greater proportion of BaP 7,8-diol and BaP 3,6- and 6,12-diones compared to other experimental groups. Additionally, microsomes from BaP-pretreated mice produced greater proportion of FLA 2, 3-diol and 2, 3 D FLA when microsomes were incubated with FLA alone or a combination of BaP and FLA. Our studies revealed that the tumor microsomes were competent to metabolize BaP and FLA either singly or in combination. The biotransformation of BaP and FLA as a consequence of prior and simultaneous exposure to BaP may influence the growth of tumors. Our findings may have relevance to human long-term dietary intake of these toxicants and the consequent acceleration of the colon carcinogenesis process.
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Affiliation(s)
- Deacqunita L Diggs
- Department of Biochemistry and Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, USA
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Jeyabalan J, Vadhanam MV, Ravoori S, Gupta RC. Sustained overexpression of CYP1A1 and 1B1 and steady accumulation of DNA adducts by low-dose, continuous exposure to benzo[a]pyrene by polymeric implants. Chem Res Toxicol 2011; 24:1937-43. [PMID: 21942922 DOI: 10.1021/tx2002788] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Many carcinogenesis and tumorigenesis studies reported in the past several decades have relied upon bolus dose(s) of test compounds to determine their DNA damage and carcinogenic potential. The high doses are far from the human scenario where exposure is almost always to low doses and for long duration. In this study, we report a novel polymeric implant system that provides continuous ("24/7") exposure to low doses using benzo[a]pyrene (BP) as a model carcinogen. Cylindrical implants (1 cm length, 3.2 mm diameter; 10 mg BP/100 mg implant) prepared from polycaprolactone:F68 (9:1) showed controlled release in vitro for long duration. To determine the rate of release and biochemical effects in vivo, groups of female Sprague-Dawley rats received either no treatment or subcutaneous sham or BP implants (1 cm, 10% load) and were euthanized after 6, 15, 30, and 180 days; the average dose of BP by the implant route was 16.7 ± 3 μg/rat. For comparison, rats were also treated with a single bolus dose of BP intraperitoneally (10 mg/rat) and euthanized at 6, 15, and 30 days. DNA adducts analyzed by (32)P-postlabeling in the lung and liver increased steadily with time with levels reaching 31 ± 3 and 17 ± 6 adducts/10(9) nucleotides, respectively, after 25 weeks; the adduct burden in the mammary tissue initially increased but then declined with time presumably due to high cell turn over. In contrast, the bolus dose treatment showed the highest DNA adduct levels after 6 days, followed by a steady decline. The steady accumulation of tissue DNA adducts in the implant groups corroborates the sustained overexpression of CYP1A1 and 1B1, the cytochrome P450s involved in the conversion of BP to its electrophilic metabolites. In contrast, the overexpression of CYP1A1 and 1B1 resulting from the bolus dose of BP lasted only for a few days. This is the first demonstration revealing that low-dose, continuous exposure to environmental polycyclic aromatic hydrocarbons such as BP can render sustained expression of CYPs and steady accumulation of tissue DNA adducts. On the basis of our recent study in which we showed the presence of 17β-estradiol in the lung, the sustained overexpression of CYP1A1 and 1B1 due to continuous exposure to BP may increase the susceptibility to estrogen-mediated carcinogenicity.
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Affiliation(s)
- Jeyaprakash Jeyabalan
- James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202, USA
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Diggs DL, Huderson AC, Harris KL, Myers JN, Banks LD, Rekhadevi PV, Niaz MS, Ramesh A. Polycyclic aromatic hydrocarbons and digestive tract cancers: a perspective. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2011; 29:324-57. [PMID: 22107166 PMCID: PMC3247201 DOI: 10.1080/10590501.2011.629974] [Citation(s) in RCA: 159] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cancers of the colon are most common in the Western world. In majority of these cases, there is no familial history and sporadic gene damage seems to play an important role in the development of tumors in the colon. Studies have shown that environmental factors, especially diet, play an important role in susceptibility to gastrointestinal (GI) tract cancers. Consequently, environmental chemicals that contaminate food or diet during preparation become important in the development of GI cancers. Polycyclic aromatic hydrocarbons (PAHs) are one such family of ubiquitous environmental toxicants. These pollutants enter the human body through consumption of contaminated food, drinking water, inhalation of cigarette smoke, automobile exhausts, and contaminated air from occupational settings. Among these pathways, dietary intake of PAHs constitutes a major source of exposure in humans. Although many reviews and books on PAHs and their ability to cause toxicity and breast or lung cancer have been published, aspects on contribution of diet, smoking and other factors toward development of digestive tract cancers, and strategies to assess risk from exposure to PAHs have received much less attention. This review, therefore, focuses on dietary intake of PAHs in humans, animal models, and cell cultures used for GI cancer studies along with epidemiological findings. Bioavailability and biotransformation processes, which influence the disposition of PAHs in body and the underlying causative mechanisms of GI cancers, are also discussed. The existing data gaps and scope for future studies is also emphasized. This information is expected to stimulate research on mechanisms of sporadic GI cancers caused by exposure to environmental carcinogens.
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Affiliation(s)
- Deacqunita L. Diggs
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
| | - Ashley C. Huderson
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
| | - Kelly L. Harris
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
| | - Jeremy N. Myers
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
| | - Leah D. Banks
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
| | - Perumalla V. Rekhadevi
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
| | - Mohammad S. Niaz
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
| | - Aramandla Ramesh
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208
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Myers JN, Rekhadevi PV, Ramesh A. Comparative evaluation of different cell lysis and extraction methods for studying benzo(a)pyrene metabolism in HT-29 colon cancer cell cultures. Cell Physiol Biochem 2011; 28:209-18. [PMID: 21865728 DOI: 10.1159/000331732] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2011] [Indexed: 01/26/2023] Open
Abstract
Lysis and extraction of cells are essential sample processing steps for investigations pertaining to metabolism of xenobiotics in cell culture studies. Of particular importance to these procedures are maintaining high lysis efficiency and analyte integrity as they influence the qualitative and quantitative distribution of drug and toxicant metabolites in the intra- and extracellular milieus. In this study we have compared the efficiency of different procedures viz. homogenization, sonication, bead beating, and molecular grinding resin treatment for disruption of HT-29 colon cells exposed to benzo(a)pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH) compound and a suspected colon carcinogen. Also, we have evaluated the efficiency of various procedures for extracting BaP parent compound/metabolites from colon cells and culture media prior to High Performance Liquid Chromatography (HPLC) analyses. The extraction procedures include solid phase extraction, solid-supported liquid- liquid extraction, liquid-liquid extraction, and homogeneous liquid- liquid extraction. Our findings showed that bead-beating in combination with detergent treatment of cell pellet coupled with liquid-liquid extraction yielded greater concentrations of BaP metabolites compared to the other methods employed. Our method optimization strategy revealed that disruption of HT-29 colon cells by a combination of mechanical and chemical lysis followed by liquid-liquid extraction is efficient and robust enough for analyzing BaP metabolites from cell culture studies.
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Affiliation(s)
- Jeremy N Myers
- Department of Biochemistry & Cancer Biology, Meharry Medical College, Nashville, USA
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Hakura A, Seki Y, Sonoda J, Hosokawa S, Aoki T, Suganuma A, Kerns WD, Tsukidate K. Rapid induction of colonic adenocarcinoma in mice exposed to benzo[a]pyrene and dextran sulfate sodium. Food Chem Toxicol 2011; 49:2997-3001. [PMID: 21827817 DOI: 10.1016/j.fct.2011.07.057] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 07/12/2011] [Accepted: 07/25/2011] [Indexed: 11/28/2022]
Abstract
Previously, we reported that the mutation frequency was markedly increased in the colon after the oral treatment of mice with an environmental mutagen/carcinogen, benzo[a]pyrene (BP); however this was not followed by tumor development. The reasons for this are as yet unresolved. The purpose of the present study is to explore the mechanisms why a high frequency of mutations induced by BP in the colon is not associated with subsequent tumor development. We show in this study that oral administration of BP to CD2F(1) mice at 125 mg/kg/day for 5 days can lead to adenocarcinomas in the mouse colon both at Weeks 4 (5/8 mice) and 11 (100% of mice), but only in the presence of inflammation induced by 4% dextran sulfate sodium (DSS) in the drinking water for up to 2 weeks. These data indicate that, in this DSS model, BP induced mutagenic events lead to tumors in the mouse colon, a tissue which is not a BP target organ. DSS-induced inflammation in a tissue primed with mutagenic risk is a key to the induction of tumors in this model. This study provides a novel, rapid and useful colon carcinogenesis model (BP/DSS model).
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Affiliation(s)
- Atsushi Hakura
- Global Drug Safety, Eisai Co. Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
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Huderson AC, Harris DL, Niaz MS, Ramesh A. Effect of benzo(a)pyrene exposure on fluoranthene metabolism by mouse adipose tissue microsomes. Toxicol Mech Methods 2010; 20:53-8. [PMID: 20158385 DOI: 10.3109/15376510903584677] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The present study has been undertaken to examine whether exposure to benzo(a)pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH) compound, influences the metabolism of fluoranthene (FLA), another PAH compound. Microsomes were isolated from the adipose tissue of mice that received 50 microg/kg BaP and incubated with FLA (3 microM) alone; FLA in combination with BaP at equimolar concentrations, and a control group that received nothing. Post-incubation, samples were extracted with ethyl acetate and analyzed for FLA metabolites by reverse-phase HPLC with fluorescence detection. The rate of FLA metabolism (pmol of metabolite/min/mg protein) was increased when microsomes from BaP-treated mice were exposed to FLA alone and FLA in combination with BaP, compared to controls. On the other hand, the difference in FLA metabolic rate between microsomes that were exposed to FLA + BaP was higher than the ones that received FLA. The microsomes from BaP-pre-treated mice produced a considerably higher proportion of FLA 2, 3-diol, and 2, 3 D FLA when microsomes were incubated with FLA. There were no differences in the FLA metabolite types formed when BaP-pre-treated mice were co-incubated with BaP and FLA than with FLA alone. The enhanced biotransformation of FLA as a result of prior and concomitant exposure to BaP may have implications for assessment of risks arising from human exposure to PAH mixtures.
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Affiliation(s)
- Ashley C Huderson
- Department of Biochemistry & Cancer Biology, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, USA
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