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Abstract
Catalase (CAT) and peroxisome proliferator activated receptor-g2 (PPARg2) are important regulators of oxidative stress and inflammation, which may contribute to the development of systemic lupus erythematosus (SLE). The objective of this study was to investigate the effects of genetic polymorphisms of CAT and PPARg2 on risk and severity of SLE in a Korean population. DNA was isolated from blood samples collected from 345 patients with SLE and 400 controls. Genotyping for the 2262C!T polymorphism of CAT and the Pro12Ala polymorphism of PPARg2 were performed by PCR-RFLP analysis. The severity of SLE was assessed using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index (SDI). No association was observed between genotypes for any of the clinical manifestations of SLE. CAT and PPARg2 genotypes were not associated with either risk or severity of SLE. For subjects who were carriers of the high activity Tallele for CATand have the Pro/Pro genotype for PPARg2, the odds ratio (95% confidence interval) for risk of SLE was 0.45 (0.23-1.08). Our results suggest that genetic polymorphisms of CAT and PPARg2 do not play a significant role in the development of SLE in a Korean population. A possible protective effect of a combined genotype warrants further investigation.
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Affiliation(s)
- K M Eny
- Department of Nutritional Sciences, University of Toronto, Toronto, Canada
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2
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Abstract
Oxidative stress caused by poor detoxification efficiency of reactive oxygen species (ROS) may play a role in the development of systemic lupus erythematosus (SLE). Glutathione S-transferase (GST) is involved in the detoxification of ROS and genetic polymorphisms of GSTM1, GSTT1 and GSTP1 are associated with altered enzyme activity. The aim of this study was to determine whether GSTM1 (deletion), GSTT1 (deletion) and GSTP1 (Ile105! Val105) polymorphisms are associated with susceptibility to SLE or frequency of clinical manifestations according to the ACR diagnostic criteria. DNA was isolated from blood samples collected from 330 patients with SLE and 270 ageand sex-matched controls. GST genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. No associations were observed between GSTM1, GSTT1, and GSTP1 genotypes and risk of SLE. Among SLE patients, the GSTM1 null genotype was associated with a lower frequency of hematological disorders ( P = 0.012), and a higher SSA(+)/SSB(2) autoantibody profile ( P = 0.042). Compared to SLE patients with the GSTT1 non-null genotype, those with the GSTT1 null genotype had a lower frequency of discoid rash ( P = 0.018), and nephritis ( P = 0.033). Our findings suggest that genetic polymorphisms of GSTM1, GSTT1, and GSTP1 do not influence the risk of SLE, but a deletion of either GSTM1 or GSTT1 may influence certain clinical manifestations of the disease.
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Affiliation(s)
- T Y Kang
- Department of Rheumatology, Wonju Christian Hospital, Wonju College of Medicine, Yonsei University, Wonju, Republic of Korea
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3
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Pataky MW, Womack CJ, Saunders MJ, Goffe JL, D'Lugos AC, El-Sohemy A, Luden ND. Caffeine and 3-km cycling performance: Effects of mouth rinsing, genotype, and time of day. Scand J Med Sci Sports 2015; 26:613-9. [DOI: 10.1111/sms.12501] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2015] [Indexed: 11/29/2022]
Affiliation(s)
- M. W. Pataky
- Department of Kinesiology; James Madison University; Harrisonburg VA USA
| | - C. J. Womack
- Department of Kinesiology; James Madison University; Harrisonburg VA USA
| | - M. J. Saunders
- Department of Kinesiology; James Madison University; Harrisonburg VA USA
| | - J. L. Goffe
- Department of Kinesiology; James Madison University; Harrisonburg VA USA
| | - A. C. D'Lugos
- Department of Kinesiology; James Madison University; Harrisonburg VA USA
| | - A. El-Sohemy
- Department of Kinesiology; James Madison University; Harrisonburg VA USA
| | - N. D. Luden
- Department of Kinesiology; James Madison University; Harrisonburg VA USA
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Kulkarni G, Chng T, Eny K, Nielsen D, Wessman C, El-Sohemy A. Association ofGLUT2andTAS1R2Genotypes with Risk for Dental Caries. Caries Res 2013; 47:219-25. [DOI: 10.1159/000345652] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 11/07/2012] [Indexed: 11/19/2022] Open
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5
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Campos Alberto E, MacLean E, Davidson C, Palikhe NS, Storie J, Tse C, Brenner D, Mayers I, Vliagoftis H, El-Sohemy A, Cameron L. The single nucleotide polymorphism CRTh2 rs533116 is associated with allergic asthma and increased expression of CRTh2. Allergy 2012; 67:1357-64. [PMID: 22947041 DOI: 10.1111/all.12003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2012] [Indexed: 02/06/2023]
Abstract
BACKGROUND CRTh2 (chemoattractant-receptor homologous molecule expressed on Th2 cells) is expressed by Th2 cells and other cells involved in allergic inflammation. Single nucleotide polymorphisms (SNPs) in CRTh2 (rs11571288, rs545659, rs634681) have been associated with various phenotypes of allergy in ethnically distinct populations. Here, we assessed the association between CRTh2 rs533116 and allergic asthma, expression of CRTh2 and Th2 cytokine production. METHODS CRTh2 rs533116 was genotyped in an ethnically diverse population (n = 1282). The proportion of cells expressing CRTh2 was determined in peripheral blood from subjects with allergic airways disease and controls as well as with in vitro differentiated Th2 cells. Receptor function was assessed by stimulating Th2 cells with the CRTh2-specific agonist 13,14-dihydro-15-keto-PGD(2) (DK-PGD(2) ) and measuring IL-4 and IL-13 by intracellular staining and ELISA. RESULTS CRTh2 rs533116 was associated with allergic asthma in White people (2.67 [1.09-6.55], P < 0.05), and expression of CRTh2 was higher in subjects with allergic airways disease compared to controls (P < 0.05). Among allergic individuals, the AA genotype was significantly associated with more eosinophils and higher expression of CRTh2 by both CD4(+) T cells and eosinophils (P < 0.05). In vitro, the AA genotype was associated with a higher proportion of CRTh2(+) cells during Th2 differentiation as well as more IL-4 and IL-13 expression following DK-PGD(2) stimulation (P < 0.05). CONCLUSIONS These findings show an association between CRTh2 rs533116 and allergic asthma and suggest this may be mediated by elevated expression of CRTh2, leading to higher numbers of circulating eosinophils and Th2 cytokine production.
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Affiliation(s)
- E. Campos Alberto
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - E. MacLean
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - C. Davidson
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - N. S. Palikhe
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - J. Storie
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - C. Tse
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - D. Brenner
- Department of Nutritional Sciences; University of Toronto; Toronto; ON; Canada
| | - I. Mayers
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - H. Vliagoftis
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
| | - A. El-Sohemy
- Department of Nutritional Sciences; University of Toronto; Toronto; ON; Canada
| | - L. Cameron
- Pulmonary Research Group; Division of Pulmonary Medicine; Department of Medicine; University of Alberta; Edmonton; AB, Canada; Canada
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Cameron L, Campos Alberto E, MacLean E, Davidson C, Brenner D, El-Sohemy A, Vliagoftis H. The Single Nucleotide Polymorphism, CRTh2-6373G>A, is Associated with Allergic Asthma and Increased Expression of CRTh2. J Allergy Clin Immunol 2012. [DOI: 10.1016/j.jaci.2011.12.694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Arora P, Garcia-Bailo B, Dastani Z, Brenner D, Villegas A, Malik S, Richards B, El-Sohemy A, Karmali M, Badawi A. P2-15 Genetic polymorphisms of innate immunity-related inflammatory pathways and their association with factors related to type 2 diabetes. Br J Soc Med 2011. [DOI: 10.1136/jech.2011.142976h.52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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8
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Brenner D, Arora P, Garica-Bailo B, El-Sohemy A, Karmali M, Badawi A. P2-32 Vitamin D in the prediction of metabolic syndrome: a target for public health intervention. Br J Soc Med 2011. [DOI: 10.1136/jech.2011.142976h.68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Brenner D, Arora P, Garcia-Bailo B, Wolever T, El-Sohemy A, Karmali M, Badawi A. P2-31 Association between plasma vitamin D and metabolic syndrome in the Canadian population. Br J Soc Med 2011. [DOI: 10.1136/jech.2011.142976h.67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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10
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Liu Z, Lee HJ, Garofalo F, Jenkins DJA, El-Sohemy A. Simultaneous Measurement of Three Tocopherols, All-trans-retinol, and Eight Carotenoids in Human Plasma by Isocratic Liquid Chromatography. J Chromatogr Sci 2011. [DOI: 10.1093/chrsci/49.3.221] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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11
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Stryjecki C, Clarke S, Nielsen D, El-Sohemy A, Ma D, Mutch D. Relationships between serum fatty acids and cRP levels in a young adult population. Can J Diabetes 2011. [DOI: 10.1016/s1499-2671(11)52270-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Mackinnon ES, El-Sohemy A, Rao AV, Rao LG. Paraoxonase 1 polymorphisms 172T→A and 584A→G modify the association between serum concentrations of the antioxidant lycopene and bone turnover markers and oxidative stress parameters in women 25-70 years of age. J Nutrigenet Nutrigenomics 2010; 3:1-8. [PMID: 20664283 DOI: 10.1159/000316636] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 06/08/2010] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Polymorphisms of the paraoxonase 1 (PON1) enzyme affect the ability to protect LDL from oxidation. Oxidative stress is a risk factor for osteoporosis and antioxidants may be beneficial for prevention. The aim of this study was to determine whether PON1 genotypes modified the association between lycopene and bone turnover markers and oxidative stress parameters. METHODS Blood samples from 107 women 25-70 years of age were analyzed for serum carotenoid concentrations, bone-specific alkaline phosphatase (BAP), N-telopeptide of type I collagen (NTx) and oxidative stress parameters. Subjects were genotyped for the 172T→A and 584A→G polymorphisms of PON1. RESULTS The 172T→A polymorphism modified the association between lycopene and NTx (p < 0.05 for interaction). In the 172TT genotype, high serum lycopene was associated with decreased NTx (p < 0.05). The 584A→G polymorphism modified the association between lycopene and BAP (p < 0.05 for interaction). Additionally, in participants with the 584GG genotype, high serum lycopene was associated with high TBA-reactive substances (p < 0.05). CONCLUSIONS These findings show that PON1 polymorphisms modify the association between serum concentrations of lycopene and oxidative stress parameters and bone turnover markers and may, therefore, moderate the risk of osteoporosis.
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Affiliation(s)
- E S Mackinnon
- Department of Medicine, Division of Endocrinology and Metabolism, St. Michael's Hospital, Toronto, Ont., Canada
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13
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Cahill L, Corey P, El-Sohemy A. The Authors Reply. Am J Epidemiol 2009. [DOI: 10.1093/aje/kwp401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Abstract
BACKGROUND There is growing evidence that DNA damage caused by mutagens found in tobacco smoke may contribute to the development of coronary heart disease (CHD). In order to bind to DNA many mutagens require metabolic activation by cytochrome P450 (CYP) 1A1 or CYP1A2. The objective of this study was to determine the effects of CYP1A1 and CYP1A2 genotypes on risk of myocardial infarction (MI) and whether smoking interacts with genotype to modify risk. METHODS Subjects (n = 873) with a first acute non-fatal MI and population based controls (n = 932) living in Costa Rica, matched for age, sex, and area of residence, were genotyped for CYP1A1*2A and CYP1A2*1F by restriction-fragment length polymorphism (RFLP)-PCR, and smoking status was determined by questionnaire. RESULTS After adjusting for matching variables and potential confounders, no association was observed between CYP1A1 genotype and risk of MI. Compared to individuals with the high inducibility CYP1A2*1A/*1A genotype, the adjusted odds ratio and 95% confidence intervals for risk of MI were 1.19 (0.97 to 1.47) for the *1A/*1F genotype and 1.55 (1.10 to 2.18) for the *1F/*1F genotype. No significant interactions were observed between smoking and either CYP1A1 or CYP1A2 genotype. CONCLUSIONS The low inducibility genotype for CYP1A2 was associated with an increased risk of MI. This effect was independent of smoking status and suggests that a substrate of CYP1A2 that is detoxified rather than activated may play a role in CHD.
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Affiliation(s)
- M C Cornelis
- Department of Nutritional Sciences, University of Toronto, Ontario, Canada M5S 3E2
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15
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El-Sohemy A, Baylin A, Ascherio A, Kabagambe E, Spiegelman D, Campos H. Population-based study of alpha- and gamma-tocopherol in plasma and adipose tissue as biomarkers of intake in Costa Rican adults. Am J Clin Nutr 2001; 74:356-63. [PMID: 11522560 DOI: 10.1093/ajcn/74.3.356] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND gamma-Tocopherol is the most abundant form of vitamin E in the US diet, but alpha-tocopherol concentrations are the highest in plasma and tissues. Although plasma and adipose tissue concentrations of alpha-tocopherol have been used as biomarkers of intake, the relation between gamma-tocopherol intake and concentrations in plasma and adipose tissue is unknown. OBJECTIVE Our goal was to investigate in a randomly selected population from Costa Rica whether plasma or adipose tissue concentrations of alpha- and gamma-tocopherol are suitable biomarkers of intake. DESIGN A total of 361 men (x +/- SD age: 55 +/- 11 y) and 121 women (aged 59 +/- 10 y) completed a 135-item food-frequency questionnaire and provided a fasting blood sample and adipose tissue biopsy sample. RESULTS Dietary gamma-tocopherol correlated with adipose tissue (r = 0.37, P < 0.001) and plasma (r = 0.42, P < 0.001) concentrations, regardless of supplement use. Dietary alpha-tocopherol correlated poorly with adipose tissue (r = 0.15, P < 0.01) and plasma (r = 0.16, P < 0.001) concentrations, and these correlations were even lower when users of vitamin supplements (n = 24) were excluded (adipose tissue: r = 0.10, P < 0.05; plasma: r = 0.09, P < 0.05). Compared with subjects who reported palm shortening (36%) as the major type of fat used for cooking, subjects using soybean oil (52%) had higher amounts of both alpha- and gamma-tocopherol in their diets. However, only gamma-tocopherol concentrations were higher in the plasma and adipose tissue of soybean oil users. CONCLUSIONS Plasma and adipose tissue concentrations of gamma-tocopherol are equally good biomarkers of intake. The weak associations between alpha-tocopherol intake and plasma or adipose tissue concentrations suggest that these biomarkers are influenced more by factors other than alpha-tocopherol intake.
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Affiliation(s)
- A El-Sohemy
- Department of Nutrition, Harvard School of Public Health, Boston 02115, USA
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Abstract
Despite convincing evidence from animal experiments, epidemiological studies linking the use of non-steroidal anti-inflammatory drugs (NSAIDs) with lower risk of breast and prostate cancer have been equivocal. One explanation for the inconsistencies among epidemiological studies may relate to individual differences in NSAID metabolism due to genetic polymorphisms in enzymes such as N -acetyltransferases and cytochrome P4502C9, which are known to be involved in the metabolic biotransformation of NSAIDs. The exclusion of these molecular biomarkers of individual susceptibility may have contributed to the inconsistent findings on the effects of NSAIDs in breast and prostate cancer.
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Affiliation(s)
- A F Badawi
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA.
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17
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El-Sohemy A. Statin drugs and the risk of fracture. JAMA 2000; 284:1921-2. [PMID: 11035877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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18
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El-Sohemy A. Statin drugs and the risk of fracture. JAMA 2000; 284:1921; author reply 1922. [PMID: 11035876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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El-Sohemy A, Archer MC. Inhibition of N-methyl-N-nitrosourea- and 7,12-dimethylbenz[a] anthracene-induced rat mammary tumorigenesis by dietary cholesterol is independent of Ha-Ras mutations. Carcinogenesis 2000; 21:827-31. [PMID: 10753223 DOI: 10.1093/carcin/21.4.827] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Dietary cholesterol has previously been shown to inhibit rat mammary tumorigenesis but the mechanisms remain unclear. Uptake of serum low density lipoprotein cholesterol by tissues leads to down-regulation of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, the rate limiting enzyme in cholesterol biosynthesis that catalyzes the formation of mevalonate. In addition to being a precursor of cholesterol, mevalonate is necessary for DNA synthesis and cell proliferation. Isoprenoids, also derived from mevalonate, are required for the post-translational modification of Ras proteins that are mutated in a number of carcinogen-induced rat mammary tumors. The purpose of this study, therefore, was to determine whether inhibition of tumorigenesis by cholesterol is dependent on the frequency of mutations in the Ha-ras gene. Female Sprague-Dawley rats (30/group) were given a single dose of either N-methyl-N-nitrosourea (MNU, 50 mg/kg i.p.) or 7, 12-dimethylbenz[a]anthracene (DMBA, 100 mg/kg intragastrally), carcinogens that produce tumors with either a high (MNU) or low (DMBA) frequency of Ha-ras mutations in codon 12 or 61, respectively. Rats were fed either a control AIN-93G diet or the control diet supplemented with 0.3% cholesterol for 14 weeks. Dietary cholesterol significantly decreased the final tumor incidence in rats given DMBA (83 versus 100%, P < 0.05) or MNU (53 versus 77%, P < 0.05). HMG-CoA reductase activity was higher in mammary tumors than in normal mammary glands, but the activity of this enzyme was reduced by cholesterol feeding only in mammary glands and not in tumors. Tumors induced by MNU had a high frequency of Ha-ras mutations in both the control (65%) and cholesterol-fed (68%) groups. Tumors induced by DMBA had a low frequency of Ha-ras mutations that also did not differ between the control (21%) and cholesterol-fed (18%) groups. These findings show that dietary cholesterol inhibits mammary tumorigenesis induced by either MNU or DMBA and that the inhibition is independent of the type or extent of mutations in the Ha-ras gene.
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Affiliation(s)
- A El-Sohemy
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, FitzGerald Building, 150 College Street, Toronto M5S 3E2, Canada
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20
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Abstract
3-Hydroxy-3-methylglutaryl (HMG)-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis, catalyzes the formation of mevalonate which is also required for cell proliferation. Changes in HMG-CoA reductase may mediate the differential effects of n-3 and n-6 polyunsaturated fatty acids (PUFA) on experimental mammary tumorigenesis, but the mechanisms by which these fatty acids regulate HMG-CoA reductase are unclear. To determine whether the low density lipoprotein receptor (LDL-R) is required for this regulation, groups of female LDL-R knockout (-/-) and wild-type (+/+) mice were fed 7% fat diets rich in either n-3 (menhaden oil) or n-6 (safflower oil) PUFA for 1 wk. Dietary PUFA and deletion of the LDL-R had independent effects on HMG-CoA reductase and serum lipids, and a significant diet-gene interaction was observed. The effects of PUFA on HMG-CoA reductase in the mammary gland, but not the liver, were mediated by the LDL-R. We also observed that differences in HMG-CoA reductase and serum LDL-cholesterol, high density lipoprotein cholesterol, and triglycerides between -/- and +/+ mice were dependent on whether the mice were fed n-3 or n-6 PUFA. Differences between -/- and +/+ mice were much greater when animals were fed n-6 PUFA rather than n-3 PUFA. These results show that the LDL-R mediates the effects of PUFA on HMG-CoA reductase in the mammary gland but not the liver. Furthermore, the composition of dietary PUFA profoundly influences the effects of deleting the LDL-R on HMG-CoA reductase and serum lipids and suggests that diet may influence the phenotype of other knock-out or transgenic animals.
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Affiliation(s)
- A El-Sohemy
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Canada
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El-Sohemy A, Archer MC. Effects of n-3 and n-6 polyunsaturated fatty acids on 3-hydroxy-3-methylglutaryl-CoA reductase in liver and mammary glands of low density lipoprotein-receptor knockout mice. Lipids 1999; 34 Suppl:S135. [PMID: 10419123 DOI: 10.1007/bf02562263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- A El-Sohemy
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Canada
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Badawi AF, El-Sohemy A, Stephen LL, Ghoshal AK, Archer MC. The effect of dietary n-3 and n-6 polyunsaturated fatty acids on the expression of cyclooxygenase 1 and 2 and levels of p21ras in rat mammary glands. Carcinogenesis 1998; 19:905-10. [PMID: 9635881 DOI: 10.1093/carcin/19.5.905] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Dietary n-6 polyunsaturated fatty acids (PUFAs) promote rat mammary cancer while n-3 PUFAs are inhibitory. The purpose of this study was to determine whether the fats exert their effects by altering the expression of genes that affect cancer development. Therefore, we have examined the effect of PUFAs on the expression of the cyclooxygenase (COX) 1 and 2 genes that are involved in prostaglandin biosynthesis. We also investigated the effect of dietary PUFAs on the expression of the p21ras protein and Ha-ras mRNA. Rats were fed either low- (7%; LF) or high- (21%; HF) fat diets that were rich in either n-6 PUFAs (safflower oil, S) or n-3 PUFAs (menhaden oil, M) for 3 weeks. COX-1 mRNA levels were approximately the same in groups fed diets containing either level of menhaden oil, but were increased by approximately 30% in the LFS and HFS groups (P < 0.05). Transcripts of the inducible COX-2 gene were not detectable in the menhaden oil groups, but this gene was expressed in animals fed either level of safflower oil and in the HFS group was associated with increased levels of COX enzymatic activity and production of PGE2. Animals fed safflower oil had elevated levels of p21ras protein compared to animals fed menhaden oil. Ha-ras mRNA was increased by approximately 35% in animals fed HFS compared to the group fed HFM (P < 0.05). These results demonstrate that dietary n-6 PUFAs upregulate COX-2 and, to some extent, COX-1 expression. There was a concomitant increase in COX enzyme activity and PG synthesis in the mammary glands of rats fed high levels of n-6 PUFAs. Together with associated changes in p21ras expression, these results may explain, at least in part, the promoting effects of dietary n-6 PUFAs on mammary carcinogenesis.
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Affiliation(s)
- A F Badawi
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada
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El-Sohemy A, Archer MC. Regulation of mevalonate synthesis in rat mammary glands by dietary n-3 and n-6 polyunsaturated fatty acids. Cancer Res 1997; 57:3685-7. [PMID: 9288773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It is well established that dietary n-6 polyunsaturated fatty acids (PU-FAs) enhance rat mammary tumor development whereas n-3 PUFAs inhibit it, yet the mechanisms are unclear. The objective of this study was to investigate a mechanism by which n-3 and n-6 PUFAs could modulate mammary carcinogenesis. Female Sprague Dawley rats were fed diets containing either menhaden (n-3) or safflower oil (n-6) in a 7% fat diet for 1 week. In comparison to the n-6 diet, the n-3 diet significantly reduced the activity and levels of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase in mammary glands, thereby suppressing the formation of mevalonate. In addition to being essential for cholesterol biosynthesis, mevalonate is also required for DNA synthesis and may be involved in malignant transformation. Serum cholesterol was lower in the n-3 group than in the n-6 group (1.91 +/- 0.18 versus 2.61 +/- 0.37 mM; P < 0.01). Extrahepatic tissues meet most of their cholesterol requirements from circulating cholesterol, and the internalized cholesterol down-regulates HMG-CoA reductase. Thus, the concomitant decrease in serum cholesterol and mammary gland HMG-CoA reductase levels suggests that changes in circulating cholesterol levels do not solely determine the activity of extrahepatic reductase. We conclude that the mevalonate pathway may be a mechanism through which different types of dietary fat modulate breast cancer development.
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Affiliation(s)
- A El-Sohemy
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Canada
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