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Djuric Z, Turgeon DK, Sen A, Ren J, Herman K, Ramaswamy D, Zhao L, Ruffin MT, Normolle DP, Smith WL, Brenner DE. The Anti-inflammatory Effect of Personalized Omega-3 Fatty Acid Dosing for Reducing Prostaglandin E 2 in the Colonic Mucosa Is Attenuated in Obesity. Cancer Prev Res (Phila) 2017; 10:729-737. [PMID: 29133307 DOI: 10.1158/1940-6207.capr-17-0091] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/12/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022]
Abstract
This clinical trial developed a personalized dosing model for reducing prostaglandin E2 (PGE2) in colonic mucosa using ω-3 fatty acid supplementation. The model utilized serum eicosapentaenoic acid (EPA, ω-3):arachidonic acid (AA, ω-6) ratios as biomarkers of colonic mucosal PGE2 concentration. Normal human volunteers were given low and high ω-3 fatty acid test doses for 2 weeks. This established a slope and intercept of the line for dose versus serum EPA:AA ratio in each individual. The slope and intercept was utilized to calculate a personalized target dose that was given for 12 weeks. This target dose was calculated on the basis of a model, initially derived from lean rodents, showing a log-linear relationship between serum EPA:AA ratios and colonic mucosal PGE2 reduction. Bayesian methods allowed addition of human data to the rodent model as the trial progressed. The dosing model aimed to achieve a serum EPA:AA ratio that is associated with a 50% reduction in colonic PGE2 Mean colonic mucosal PGE2 concentrations were 6.55 ng/mg protein (SD, 5.78) before any supplementation and 3.59 ng/mg protein (SD, 3.29) after 12 weeks of target dosing. In secondary analyses, the decreases in PGE2 were significantly attenuated in overweight and obese participants. This occurred despite a higher target dose for the obese versus normal weight participants, as generated by the pharmacodynamic predictive model. Large decreases also were observed in 12-hydroxyicosatetraenoic acids, and PGE3 increased substantially. Future biomarker-driven dosing models for cancer prevention therefore should consider energy balance as well as overall eicosanoid homeostasis in normal tissue. Cancer Prev Res; 10(12); 729-37. ©2017 AACR.
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Affiliation(s)
- Zora Djuric
- Department of Family Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
| | - D Kim Turgeon
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Ananda Sen
- Department of Family Medicine, University of Michigan Medical School, Ann Arbor, Michigan.,Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan
| | - Jianwei Ren
- Department of Family Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Kirk Herman
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Devon Ramaswamy
- Department of Family Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Lili Zhao
- Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan
| | - Mack T Ruffin
- Department of Family and Community Medicine, Penn State Hershey Medical Center, Hershey, Pennsylvania
| | - Daniel P Normolle
- Department of Biostatistics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania
| | - William L Smith
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan
| | - Dean E Brenner
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.,Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan
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Durand S, Trillet K, Uguen A, Saint-Pierre A, Le Jossic-Corcos C, Corcos L. A transcriptome-based protein network that identifies new therapeutic targets in colorectal cancer. BMC Genomics 2017; 18:758. [PMID: 28962550 PMCID: PMC5622428 DOI: 10.1186/s12864-017-4139-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 09/13/2017] [Indexed: 01/22/2023] Open
Abstract
Background Colon cancer occurrence is increasing worldwide, making it the third most frequent cancer. Although many therapeutic options are available and quite efficient at the early stages, survival is strongly decreased when the disease has spread to other organs. The identification of molecular markers of colon cancer is likely to help understanding its course and, eventually, to uncover novel genes to be targeted by drugs. In this study, we compared gene expression in a set of 95 human colon cancer samples to that in 19 normal colon mucosae, focusing on 401 genes from 5 selected pathways (Apoptosis, Cancer, Cholesterol metabolism and lipoprotein signaling, Drug metabolism, Wnt/beta-catenin). Deregulation of mRNA levels largely matched that of proteins, leading us to build in silico protein networks, starting from mRNA levels, to identify key proteins central to network activity. Results Among the analyzed genes, 10.5% (42) had no reported link with colon cancer, including the SFRP1, IGF1 and ADH1B (down), and MYC and IL8 (up), whose encoded proteins were most interacting with other proteins from the same or even distinct networks. Analyzing all pathways globally led us to uncover novel functional links between a priori unrelated or rather remotely connected pathways, such as the Drug metabolism and the Cancer pathways or, even more strikingly, between the Cholesterol metabolism and lipoprotein signaling and the Cancer pathways. In addition, we analyzed the responsiveness of some of the deregulated genes essential to network activities, to chemotherapeutic agents used alone or in presence of Lovastatin, a lipid-lowering drug. Some of these treatments could oppose the deregulations occurring in cancer samples, including those of the CHECK2, CYP51A1, HMGCS1, ITGA2, NME1 or VEGFA genes. Conclusions Our network-based approach allowed discovering genes not previously known to play regulatory roles in colon cancer. Our results also showed that selected drug treatments might revert the cancer-specific deregulation of genes playing prominent roles within the networks operating to maintain colon homeostasis. Among those genes, some could constitute novel testable targets to eliminate colon cancer cells, either directly or, potentially, through the use of lipid-lowering drugs such as statins, in association with selected anticancer drugs. Electronic supplementary material The online version of this article (10.1186/s12864-017-4139-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stéphanie Durand
- INSERM 1078 Unit, "Cancérologie appliquée et épissage alternatif" team, Brest Institute of Health, Agronomy and Material (IBSAM), Faculty of medicine, University of Western Brittany (UBO), 22 avenue Camille Desmoulins, F-29200, Brest, France
| | - Killian Trillet
- INSERM 1078 Unit, "Cancérologie appliquée et épissage alternatif" team, Brest Institute of Health, Agronomy and Material (IBSAM), Faculty of medicine, University of Western Brittany (UBO), 22 avenue Camille Desmoulins, F-29200, Brest, France
| | - Arnaud Uguen
- INSERM 1078 Unit, "Cancérologie appliquée et épissage alternatif" team, Brest Institute of Health, Agronomy and Material (IBSAM), Faculty of medicine, University of Western Brittany (UBO), 22 avenue Camille Desmoulins, F-29200, Brest, France.,Department of Pathology, Brest University Hospital, F-29200, Brest, France
| | - Aude Saint-Pierre
- INSERM 1078 Unit, "Epidemiology, genetic Epidemiology and population genetics" team, 46 rue Félix Le Dantec, F-29200, Brest, France
| | - Catherine Le Jossic-Corcos
- INSERM 1078 Unit, "Cancérologie appliquée et épissage alternatif" team, Brest Institute of Health, Agronomy and Material (IBSAM), Faculty of medicine, University of Western Brittany (UBO), 22 avenue Camille Desmoulins, F-29200, Brest, France
| | - Laurent Corcos
- INSERM 1078 Unit, "Cancérologie appliquée et épissage alternatif" team, Brest Institute of Health, Agronomy and Material (IBSAM), Faculty of medicine, University of Western Brittany (UBO), 22 avenue Camille Desmoulins, F-29200, Brest, France. .,INSERM 1078 Unit, "Cancérologie appliquée et épissage alternatif" laboratory, University of Western Brittany (UBO), Faculty of medicine, 22, rue Camille Desmoulins, 29200, Brest, France.
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3
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Djuric Z. Obesity-associated cancer risk: the role of intestinal microbiota in the etiology of the host proinflammatory state. Transl Res 2017; 179:155-167. [PMID: 27522986 PMCID: PMC5164980 DOI: 10.1016/j.trsl.2016.07.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/10/2016] [Accepted: 07/20/2016] [Indexed: 02/06/2023]
Abstract
Obesity increases the risks of many cancers. One important mechanism behind this association is the obesity-associated proinflammatory state. Although the composition of the intestinal microbiome undoubtedly can contribute to the proinflammatory state, perhaps the most important aspect of host-microbiome interactions is host exposure to components of intestinal bacteria that stimulate inflammatory reactions. Systemic exposures to intestinal bacteria can be modulated by dietary factors through altering both the composition of the intestinal microbiota and the absorption of bacterial products from the intestinal lumen. In particular, high-fat and high-energy diets have been shown to facilitate absorption of bacterial lipopolysaccharide (LPS) from intestinal bacteria. Biomarkers of bacterial exposures that have been measured in blood include LPS-binding protein, sCD14, fatty acids characteristic of intestinal bacteria, and immunoglobulins specific for bacterial LPS and flagellin. The optimal strategies to reduce these proinflammatory exposures, whether by altering diet composition, avoiding a positive energy balance, or reducing adipose stores, likely differ in each individual. Biomarkers that assess systemic bacterial exposures therefore should be useful to (1) optimize and personalize preventive approaches for individuals and groups with specific characteristics and to (2) gain insight into the possible mechanisms involved with different preventive approaches.
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Affiliation(s)
- Zora Djuric
- Department of Family Medicine, University of Michigan, Ann Arbor, Mich; Department of Nutritional Sciences, University of Michigan, Ann Arbor, Mich.
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Tan NS, Vázquez-Carrera M, Montagner A, Sng MK, Guillou H, Wahli W. Transcriptional control of physiological and pathological processes by the nuclear receptor PPARβ/δ. Prog Lipid Res 2016; 64:98-122. [PMID: 27665713 DOI: 10.1016/j.plipres.2016.09.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 08/31/2016] [Accepted: 09/20/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Nguan Soon Tan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Academia, 20 College Road, 169856, Singapore; Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Agency for Science Technology & Research, 138673, Singapore; KK Research Centre, KK Women's and Children's Hospital, 100 Bukit Timah Road, 229899, Singapore.
| | - Manuel Vázquez-Carrera
- Department of Pharmacology and Therapeutic Chemistry, Faculty of Pharmacy, University of Barcelona, Institute of Biomedicine of the University of Barcelona (IBUB), Pediatric Research Institute-Hospital Sant Joan de Déu, Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Diseases (CIBERDEM), Barcelona, Spain
| | | | - Ming Keat Sng
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Academia, 20 College Road, 169856, Singapore
| | - Hervé Guillou
- INRA ToxAlim, UMR1331, Chemin de Tournefeuille, Toulouse Cedex 3, France
| | - Walter Wahli
- Lee Kong Chian School of Medicine, Nanyang Technological University, Academia, 20 College Road, 169856, Singapore; INRA ToxAlim, UMR1331, Chemin de Tournefeuille, Toulouse Cedex 3, France; Center for Integrative Genomics, University of Lausanne, Le Génopode, CH 1015 Lausanne, Switzerland.
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5
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Su CW, Zhang Y, Zhu YT. Stromal COX-2 signaling are correlated with colorectal cancer: A review. Crit Rev Oncol Hematol 2016; 107:33-38. [PMID: 27823649 DOI: 10.1016/j.critrevonc.2016.08.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/04/2016] [Accepted: 08/23/2016] [Indexed: 12/20/2022] Open
Abstract
Cyclooxygenase-2 (COX-2) and its product prostaglandin E2 (PGE2) play a critical role in development and progression of colorectal cancer. Yet the detailed mechanistic pathways of COX-2 mediated signaling are still controversial and the role of COX-2 interaction in epithelial-stromal compartments on colorectal carcinogenesis is not well-understood either. In this review, we provide experimental evidence to support that (1) COX-2 signaling plays a major role in development and progression of colorectal cancer; (2) Stromal fibroblasts are a major source of COX-2 and PGE2; (3) Stromal-epithelial interaction mediated by COX-2 signaling promotes colorectal carcinogenesis and (4) Inhibition of stromal COX-2 signaling is necessary to control colorectal cancer. In conclusion, the evidences summarized in the review reflect recent advances and insight in mechanistic studies of colorectal cancer which can help the audiences to further understand the etiology and the control of this disease.
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Affiliation(s)
- Chen-Wei Su
- R&D Department, TissueTech, Inc., Ocular Surface Center, Ocular Surface Research & Education Foundation, Miami, FL, USA
| | - Yuan Zhang
- Dalian Central Hospital, Dalian City, Liaoning Province, China
| | - Ying-Ting Zhu
- R&D Department, TissueTech, Inc., Ocular Surface Center, Ocular Surface Research & Education Foundation, Miami, FL, USA.
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Dinh CHL, Yu Y, Szabo A, Zhang Q, Zhang P, Huang XF. Bardoxolone Methyl Prevents High-Fat Diet-Induced Colon Inflammation in Mice. J Histochem Cytochem 2016; 64:237-55. [PMID: 26920068 DOI: 10.1369/0022155416631803] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Accepted: 01/18/2016] [Indexed: 02/08/2023] Open
Abstract
Obesity induces chronic, low-grade inflammation, which increases the risk of colon cancer. We investigated the preventive effects of Bardoxolone methyl (BARD) on high-fat diet (HFD)-induced inflammation in a mouse colon. Male C57BL/6J mice (n=7) were fed a HFD (HFD group), HFD plus BARD (10 mg/kg) in drinking water (HFD/BARD group), or normal laboratory chow diet (LFD group) for 21 weeks. In HFD mice, BARD reduced colon thickness and decreased colon weight per length. This was associated with an increase in colon crypt depth and the number of goblet cells per crypt. BARD reduced the expression of F4/80 and CD11c but increased CD206 and IL-10, indicating an anti-inflammatory effect. BARD prevented an increase of the intracellular pro-inflammatory biomarkers (NF-қB, p NF-қB, IL-6, TNF-α) and cell proliferation markers (Cox2 and Ki67). BARD prevented fat deposition in the colon wall and prevented microbial population changes. Overall, we report the preventive effects of BARD on colon inflammation in HFD-fed mice through its regulation of macrophages, NF-қB, cytokines, Cox2 and Ki67, fat deposition and microflora.
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Affiliation(s)
- Chi H L Dinh
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia (CHLD, YY, AS, QZ, XH)
| | - Yinghua Yu
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia (CHLD, YY, AS, QZ, XH)
| | - Alexander Szabo
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia (CHLD, YY, AS, QZ, XH),ANSTO LifeSciences, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia (AS)
| | - Qingsheng Zhang
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia (CHLD, YY, AS, QZ, XH)
| | - Peng Zhang
- XuZhou Medical College, Jiangsu Province 221004, The People's Republic of China (PZ)
| | - Xu-Feng Huang
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia (CHLD, YY, AS, QZ, XH)
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7
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Amor S, Iglesias-de la Cruz MC, Ferrero E, García-Villar O, Barrios V, Fernandez N, Monge L, García-Villalón AL, Granado M. Peritumoral adipose tissue as a source of inflammatory and angiogenic factors in colorectal cancer. Int J Colorectal Dis 2016; 31:365-75. [PMID: 26493186 DOI: 10.1007/s00384-015-2420-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/14/2015] [Indexed: 02/04/2023]
Abstract
PURPOSE Obesity is a risk factor for the development of human colorectal cancer (CC). The aim of this work is to report the inflammatory and angiogenic scenario in lean (BMI < 25 kg/m2) and obese (BMI > 30 kg/m2) patients with and without CC and to assess the role of peritumoral adipose tissue in CC-induced inflammation. MATERIAL AND METHODS Patients were divided in four experimental groups: obese patients with CC (OB-CC), lean patients with CC (LEAN-CC), obese patients without CC (OB), and lean patients without CC (LEAN). RESULTS Plasma levels of pro-inflammatory cytokines (interleukin (IL)-6, IL-4, IL-8) and granulocyte-macrophage colony-stimulating factor (GM-CSF) were increased in OB-CC patients. Peritumoral adipose tissue (TF) explants and cultured mature adipocytes secreted higher amounts of nitrites and nitrates than did control and non-tumoral (NTF) adipose tissue both alone and in response to lipopolysaccharide (LPS). Nitrite and nitrate secretion was also increased in TF explants from OB-CC patients compared with that from LEAN-CC patients. Gene expression of adiponectin, tumor necrosis factor alpha (TNF-α), insulin-like growth factor type I (IGF-I), cyclooxygenase-2 (COX-2), and peroxisome proliferator-activated receptor γ (PPAR-γ) was increased in TF explants from CC patients. LPS increased the gene expression of IL-6, IL-10, TNF-α, vascular endothelial growth factor (VEGF), and COX-2 in OB and in TF explants from OB-CC patients. COX-2 and PPAR-γ inhibition further increased LPS-induced release of nitrites and nitrates in TF explants and adipocytes from OB-CC patients. CONCLUSIONS In conclusion, OB-CC patients have increased plasma levels of pro-inflammatory and angiogenic factors. TF from OB-CC patients shows an increased secretion of inflammatory markers compared with both TF from LEAN-CC and non-tumoral adipose tissue (AT) through a COX-2- and PPAR-γ-independent mechanism.
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Chen J, Xu T, Chen C. The critical roles of miR-21 in anti-cancer effects of curcumin. ANNALS OF TRANSLATIONAL MEDICINE 2016; 3:330. [PMID: 26734640 DOI: 10.3978/j.issn.2305-5839.2015.09.20] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Curcumin is a well-known phytochemical that has various anti-cancer effects. Although it has been demonstrated that curcumin can inhibit multiple signalling pathways, the exact mechanisms for its demonstrated anti-cancer effects are not fully understood. Recent studies have revealed that curcumin may affect cancer initiation and progression through regulating microRNAs (miRs). In this review, we focus on the roles of microRNA-21 (miR-21) in the anti-cancer effects of curcumin and regulatory mechanisms for the effects of curcumin on miR-21. MiR-21 mediates various effects of curcumin on cancer cells including proliferation, apoptosis, metastasis and anti-cancer drug resistance. Several downstream pathways of miR-21 have been identified including phosphatase and tensin homolog (PTEN)/phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), programmed cell death protein 4 (PDCD4) and NF-κB pathways. Curcumin decreases miR-21 levels through both increasing miR-21 exosome exclusion from the cells and inhibiting the transcription of the miR-21 gene in the cells by binding to its promoter.
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Affiliation(s)
- Jiezhong Chen
- 1 School of Biomedical Sciences, The University of Queensland, St Lucia, QLD4072, Australia ; 2 Cancer Institute of Hainan Medical College, Affiliated Hospital of Hainan Medical College, Haikou 570102, China
| | - Tiefeng Xu
- 1 School of Biomedical Sciences, The University of Queensland, St Lucia, QLD4072, Australia ; 2 Cancer Institute of Hainan Medical College, Affiliated Hospital of Hainan Medical College, Haikou 570102, China
| | - Chen Chen
- 1 School of Biomedical Sciences, The University of Queensland, St Lucia, QLD4072, Australia ; 2 Cancer Institute of Hainan Medical College, Affiliated Hospital of Hainan Medical College, Haikou 570102, China
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Nguyen T, Tang Z, Younes M, Alsarraj A, Ramsey D, Fitzgerald S, Kramer JR, El-Serag HB. Esophageal COX-2 expression is increased in Barrett's esophagus, obesity, and smoking. Dig Dis Sci 2015; 60:65-73. [PMID: 25185658 DOI: 10.1007/s10620-014-3333-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 08/11/2014] [Indexed: 01/14/2023]
Abstract
BACKGROUND Increased esophageal cyclooxygenase-2 (COX-2) expression has been associated with Barrett's esophagus (BE); however, it is unknown whether COX-2 expression varies among patient groups with different clinical or socio-demographic factors. METHODS We conducted a case-control study among eligible patients scheduled for elective esophagogastroduodenoscopy and patients eligible for screening colonoscopy recruited from primary clinics. We compared 39 BE tissue samples and 47 squamous tissue samples from BE cases and 240 squamous tissue samples from controls. Clinical and socio-demographic data were prospectively collected. Immunohistochemical staining for esophageal COX-2 was performed and scored. RESULTS The median COX-2 score was significantly higher in BE tissue than squamous tissue from cases or controls (p < 0.001). Median COX-2 expression levels were higher in tissue samples from participants with a waist-to-hip ratio (WHR) in the 2nd tertile [unadjusted odds ratio (OR) 2.04; 95 % confidence interval (95 % CI) 1.17-3.57] and 3rd tertile (unadjusted OR 2.24; 95 % CI 1.20-4.16) compared with the 1st tertile and from current smokers compared with former or non-smokers (unadjusted OR 1.68; 95 % CI 1.03-2.75). In the multivariate analysis, WHRs in the 2nd tertile (OR 1.92; 95 % CI 1.07-3.45) and the 3rd tertile (OR 2.14; 95 % CI 1.10-4.16) were associated with high COX-2 compared with the 1st tertile, as was current smoking (OR 1.78; 95 % CI 1.06-2.97) compared with former and non-smoking. CONCLUSION We found a significant association between elevated esophageal mucosa COX-2 levels and the presence of BE tissue, as well as between elevated COX-2 levels and high WHR and current tobacco smoking. This information may assist in identifying patients likely to benefit from chemoprevention with COX-2 inhibitors.
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Affiliation(s)
- Theresa Nguyen
- Houston VA HSR&D Center for Innovations in Quality, Effectiveness and Safety, Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC 152), 2002 Holcombe Blvd., Houston, TX, 77030, USA
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Wang D, DuBois RN. PPARδ and PGE 2 signaling pathways communicate and connect inflammation to colorectal cancer. INFLAMMATION AND CELL SIGNALING 2014; 1. [PMID: 26290896 DOI: 10.14800/ics.338] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The nuclear hormone receptor peroxisome proliferator-activated receptor δ (PPARδ) is a ligand-dependent transcription factor that is involved in fatty acid metabolism, obesity, wound healing, inflammation, and cancer. Despite decades of research, the role of PPARδ in inflammation and colorectal cancer remains unclear and somewhat controversial. Our recent work presented the first genetic evidence demonstrating that PPARδ is required for chronic colonic inflammation and colitis-associated carcinogenesis. We also found that a PPARδ downstream pathway, namely the COX-2-derived PGE2 signaling, mediated crosstalk between tumor epithelial cells and macrophages to promote chronic inflammation and colitis-associated tumor genesis. In this brief review, we summarize recent studies on the role of PPARδ in inflammatory bowel disease (IBD) and colorectal cancer (CRC) and highlight recent advances in our understanding of how PPARδ and COX-2-drevided PGE2 signaling coordinately promote chronic colonic inflammation and colitis-associate tumorigenesis. Elucidating the role of PPARδ in inflammation and CRC may provide a rationale for development of PPARδ antagonists as new therapeutic agents in treatment of IBD and CRC.
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Affiliation(s)
- Dingzhi Wang
- Laboratory for Inflammation and Cancer, the Biodesign Institute at Arizona State University, Tempe, AZ 85287
| | - Raymond N DuBois
- Laboratory for Inflammation and Cancer, the Biodesign Institute at Arizona State University, Tempe, AZ 85287 ; Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287 ; Department of Research and Division of Gastroenterology, Mayo Clinic, Scottsdale, AZ 85259
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11
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Neels JG, Grimaldi PA. Physiological functions of peroxisome proliferator-activated receptor β. Physiol Rev 2014; 94:795-858. [PMID: 24987006 DOI: 10.1152/physrev.00027.2013] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The peroxisome proliferator-activated receptors, PPARα, PPARβ, and PPARγ, are a family of transcription factors activated by a diversity of molecules including fatty acids and fatty acid metabolites. PPARs regulate the transcription of a large variety of genes implicated in metabolism, inflammation, proliferation, and differentiation in different cell types. These transcriptional regulations involve both direct transactivation and interaction with other transcriptional regulatory pathways. The functions of PPARα and PPARγ have been extensively documented mainly because these isoforms are activated by molecules clinically used as hypolipidemic and antidiabetic compounds. The physiological functions of PPARβ remained for a while less investigated, but the finding that specific synthetic agonists exert beneficial actions in obese subjects uplifted the studies aimed to elucidate the roles of this PPAR isoform. Intensive work based on pharmacological and genetic approaches and on the use of both in vitro and in vivo models has considerably improved our knowledge on the physiological roles of PPARβ in various cell types. This review will summarize the accumulated evidence for the implication of PPARβ in the regulation of development, metabolism, and inflammation in several tissues, including skeletal muscle, heart, skin, and intestine. Some of these findings indicate that pharmacological activation of PPARβ could be envisioned as a therapeutic option for the correction of metabolic disorders and a variety of inflammatory conditions. However, other experimental data suggesting that activation of PPARβ could result in serious adverse effects, such as carcinogenesis and psoriasis, raise concerns about the clinical use of potent PPARβ agonists.
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Affiliation(s)
- Jaap G Neels
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
| | - Paul A Grimaldi
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
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12
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Zuo X, Xu M, Yu J, Wu Y, Moussalli MJ, Manyam GC, Lee SI, Liang S, Gagea M, Morris JS, Broaddus RR, Shureiqi I. Potentiation of colon cancer susceptibility in mice by colonic epithelial PPAR-δ/β overexpression. J Natl Cancer Inst 2014; 106:dju052. [PMID: 24681603 DOI: 10.1093/jnci/dju052] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND The nuclear receptor peroxisome proliferator-activated receptor-δ/β (PPAR-d) is upregulated in human colorectal cancers, but its role in colonic tumorigenesis remains controversial. METHODS We generated a novel mouse model of intestinally targeted PPAR-d overexpression to simulate PPAR-d upregulation in human colon carcinogenesis. Colon-specific PPAR-d overexpression was confirmed by real-time reverse transcription polymerase chain reaction, immunoblotting, and activity assays. Mice with and without targeted PPAR-d overexpression were tested for azoxymethane (AOM)-induced colonic tumorigenesis. Mouse whole-genome transcriptome microarray analyses were performed to identify PPAR-d target genes to promote tumorigenesis. We used linear models to test for PPAR-d overexpression trend effects on tumor multiplicity. All statistical tests were two-sided. RESULTS Targeted PPAR-d overexpression markedly increased colonic tumor incidence (from 0 of 10 wild-type [WT] littermate mice to 9 of 10 mice [P < .001] in 2 FVB/N background mouse lines [villin-PPAR-d-1 and villin-PPAR-d-2] at a 5-mg/kg AOM dose) and multiplicity (number of tumors per mouse per mg/kg dose of AOM increased from 0.47 [95% confidence interval [CI] = 0.22 to 0.72] for the WT littermates to 2.15 [95% CI = 1.90 to 2.40] [P < .001] for the villin-PPAR-d-1 mice and from 0.44 [95% CI = 0.09 to 0.79] for the WT littermates to 1.91 [95% CI = 1.57 to 2.25] [P < .001] for the villin-PPAR-d-2 mice). PPAR-d overexpression reversed resistance to AOM-induced colonic tumorigenesis in C57BL/6 mice. PPAR-d overexpression modulated expression of several novel PPAR-d target genes in normal-appearing colonic epithelial cells of mice with PPAR-d overexpression in a pattern that matched the changes in colonic tumors. CONCLUSIONS Our finding that PPAR-d upregulation profoundly enhances susceptibility to colonic tumorigenesis should impact the development of strategies of molecularly targeting PPAR-d in cancer and noncancerous diseases.
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Affiliation(s)
- Xiangsheng Zuo
- Affiliations of authors: Department of Gastrointestinal Medical Oncology (XZ, MX, JY, IS), Department of Clinical Cancer Prevention (XZ, YW, IS), Department of Pathology (MJM, RRB), Department of Bioinformatics & Computational Biology (GCM, SL), Department of Veterinary Medicine and Surgery (MG), and Department of Biostatistics (JSM), University of Texas MD Anderson Cancer Center, Houston, TX
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13
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Partial lipectomy reduces dimethylhydrazine-induced carcinogenic initiation in the colon of rats. Toxicology 2014; 316:9-13. [DOI: 10.1016/j.tox.2013.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 11/19/2013] [Accepted: 11/22/2013] [Indexed: 12/11/2022]
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14
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Roelofs HMJ, Te Morsche RHM, van Heumen BWH, Nagengast FM, Peters WHM. Over-expression of COX-2 mRNA in colorectal cancer. BMC Gastroenterol 2014; 14:1. [PMID: 24383454 PMCID: PMC3880419 DOI: 10.1186/1471-230x-14-1] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 12/20/2013] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Cyclooxygenase-2 (COX-2, PTGS2) is an enzyme involved in the synthesis of prostaglandins and thromboxanes, which are regulators of biologic processes such as inflammation, cell proliferation and angiogenesis. COX-2 over-expression was reported in many (pre) malignant tissues, but data strongly vary and seem to depend on the methodology used. METHODS Normal colorectal mucosa and paired cancerous tissue from 60 patients with colorectal cancer was investigated for the levels of COX-2 mRNA by real-time quantitative Polymerase Chain Reaction (qPCR). COX-2 levels were expressed relative to either: tissue weight or levels of the housekeeping genes beta-2 microglobulin (B2M) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). RESULTS COX-2 mRNA levels, normalized with respect to tissue weight or mRNA levels of the housekeeping genes B2M or GAPDH, were over-expressed in 80%, 70% and 40% of the colorectal tumor tissues, as compared to the paired adjacent normal colorectal mucosa samples, respectively. Highest mRNA COX-2 ratios tumor/normal were measured when expressed per mg tissue (mean ratio 21.6). When normalized with respect to the housekeeping genes B2M or GAPDH, mean tumor/normal ratios were 16.1 and 7.5, respectively. CONCLUSION Expression of COX-2 mRNA levels per mg tissue is most simple in comparison to normalization with respect to the housekeeping genes B2M or GAPDH. Levels of COX-2 mRNA are found over-expressed in almost 80% of the colorectal tumors, compared to paired adjacent normal colorectal mucosa, suggesting a role of COX-2 as a potential biomarker for cancer risk, whereas inhibitors of COX-2 could be of value in chemoprevention of colon cancer.
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Affiliation(s)
| | | | | | | | - Wilbert H M Peters
- Department of Gastroenterology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands.
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15
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Potential targets for colorectal cancer prevention. Int J Mol Sci 2013; 14:17279-303. [PMID: 23975167 PMCID: PMC3794728 DOI: 10.3390/ijms140917279] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/09/2013] [Accepted: 08/14/2013] [Indexed: 12/18/2022] Open
Abstract
The step-wise development of colorectal neoplasia from adenoma to carcinoma suggests that specific interventions could delay or prevent the development of invasive cancer. Several key factors involved in colorectal cancer pathogenesis have already been identified including cyclooxygenase 2 (COX-2), nuclear factor kappa B (NF-κB), survivin and insulin-like growth factor-I (IGF-I). Clinical trials of COX-2 inhibitors have provided the “proof of principle” that inhibition of this enzyme can prevent the formation of colonic adenomas and potentially carcinomas, however concerns regarding the potential toxicity of these drugs have limited their use as a chemopreventative strategy. Curcumin, resveratrol and quercetin are chemopreventive agents that are able to suppress multiple signaling pathways involved in carcinogenesis and hence are attractive candidates for further research.
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16
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Xu M, Zuo X, Shureiqi I. Targeting peroxisome proliferator-activated receptor-β/δ in colon cancer: how to aim? Biochem Pharmacol 2012; 85:607-611. [PMID: 23041232 DOI: 10.1016/j.bcp.2012.09.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 09/26/2012] [Accepted: 09/27/2012] [Indexed: 12/18/2022]
Abstract
Peroxisome proliferator-activated receptor-β/δ (PPARδ) is a ubiquitously expressed, ligand-activated transcriptional factor that performs diverse critical functions in normal cells (e.g., fatty acid metabolism, obesity, apoptosis, and inflammation). Various studies in humans have found that PPARδ is upregulated in primary colorectal cancers; however, these findings have been challenged by those of other reports. Similarly, various in vitro and in vivo mechanistic pre-clinical models have yielded data demonstrating that PPARδ promotes colonic tumorigenesis, but other models have yielded data that contradicts this notion. Definitive studies are therefore needed to establish the exact role of PPARδ in human colorectal tumorigenesis and to provide a theoretical basis for PPARδ therapeutic targeting.
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Affiliation(s)
- Min Xu
- Department of Gastrointestinal Medical Oncology, Unit 0426, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4009, USA; Department of Gastroenterology, Affiliated Hospital of Jiangsu University, 438 Jiefang Road, Zhenjiang, Jiangsu 212001, PR China
| | - Xiangsheng Zuo
- Department of Gastrointestinal Medical Oncology, Unit 0426, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4009, USA
| | - Imad Shureiqi
- Department of Gastrointestinal Medical Oncology, Unit 0426, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4009, USA.
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Peters JM, Shah YM, Gonzalez FJ. The role of peroxisome proliferator-activated receptors in carcinogenesis and chemoprevention. Nat Rev Cancer 2012; 12:181-95. [PMID: 22318237 PMCID: PMC3322353 DOI: 10.1038/nrc3214] [Citation(s) in RCA: 350] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that are involved in regulating glucose and lipid homeostasis, inflammation, proliferation and differentiation. Although all of these functions might contribute to the influence of PPARs in carcinogenesis, there is a distinct need for a review of the literature and additional experimentation to determine the potential for targeting PPARs for cancer therapy and cancer chemoprevention. As PPAR agonists include drugs that are used for the treatment of metabolic diseases, a more complete understanding of the roles of PPARs in cancer will aid in determining any increased cancer risk for patients undergoing therapy with PPAR agonists.
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Affiliation(s)
- Jeffrey M Peters
- Department of Veterinary and Biomedical Sciences and The Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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18
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Abstract
A Mediterranean diet appears to have health benefits in many domains of human health, mediated perhaps by its anti-inflammatory effects. Metabolism of fatty acids and subsequent eicosanoid production is a key mechanism by which a Mediterranean diet can exert anti-inflammatory effects. Both dietary fatty acids and fatty acid metabolism determine fatty acid availability for cyclooxygenase- and lipoxygenase-dependent production of eicosanoids, namely prostaglandins and leukotrienes. In dietary intervention studies and in observational studies of the Mediterranean diet, blood levels of fatty acids do reflect dietary intakes but are attenuated. Small differences in fatty acid levels, however, appear to be important, especially when exposures occur over long periods of time. This review summarizes how fat intakes from a Greek-style Mediterranean diet can be expected to affect fatty acid metabolizing proteins, with an emphasis on the metabolic pathways that lead to the formation of proinflammatory eicosanoids. The proteins involved in these pathways are ripe for investigation using proteomic approaches and may be targets for colon cancer prevention.
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Affiliation(s)
- Zora Djuric
- Department of Family Medicine, University of Michigan, Ann Arbor, Michigan 48109-5930, USA.
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19
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Zhang X, Smith-Warner SA, Chan AT, Wu K, Spiegelman D, Fuchs CS, Willett WC, Giovannucci EL. Aspirin use, body mass index, physical activity, plasma C-peptide, and colon cancer risk in US health professionals. Am J Epidemiol 2011; 174:459-67. [PMID: 21673123 DOI: 10.1093/aje/kwr115] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Aspirin use decreases colon cancer risk, but this association may vary among population subgroups. The aspirin-colon cancer association was evaluated according to body mass index and physical activity in 1,701 incident colon cancer cases diagnosed during follow-up of 139,310 participants for up to 26 years in 2 US prospective cohort studies that began in 1980 and 1992, respectively. Whether plasma C-peptide levels modified the association was examined by using a nested case-control design (n = 384 cases, 749 controls). Multiplicative and additive interactions were tested. Body mass index did not modify the association; pooled multivariable relative risks for regular aspirin use versus nonuse ranged from 0.74 to 0.75 in the normal weight and obese groups (test for multiplicative interaction, P = 0.75; test for additive interaction, P = 0.66). Pooled multivariable relative risks for regular aspirin use were 0.86 (95% confidence interval (CI): 0.66, 1.11) in the low and 0.67 (95% CI: 0.58, 0.77) in the high physical activity groups with no interaction evident on either the multiplicative or additive scale (P > 0.10). Plasma C-peptide levels also did not modify the aspirin-colon cancer association, with multivariable relative risks of 0.74 (95% CI: 0.50, 1.10) for the low and 0.65 (95% CI: 0.46, 0.92) for the high group. Reductions in colon cancer risk associated with aspirin use were not significantly modified by body mass index, physical activity, or plasma C-peptide level in this study.
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Affiliation(s)
- Xuehong Zhang
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.
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20
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Papi A, Rocchi P, Ferreri AM, Orlandi M. RXRγ and PPARγ ligands in combination to inhibit proliferation and invasiveness in colon cancer cells. Cancer Lett 2010; 297:65-74. [DOI: 10.1016/j.canlet.2010.04.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/21/2010] [Accepted: 04/27/2010] [Indexed: 12/13/2022]
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21
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Chan AT, Giovannucci EL. Primary prevention of colorectal cancer. Gastroenterology 2010; 138:2029-2043.e10. [PMID: 20420944 PMCID: PMC2947820 DOI: 10.1053/j.gastro.2010.01.057] [Citation(s) in RCA: 411] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 01/10/2010] [Accepted: 01/14/2010] [Indexed: 02/07/2023]
Abstract
Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.
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Affiliation(s)
- Andrew T. Chan
- Massachusetts General Hospital, Gastrointestinal Unit, 55 Fruit Street, GRJ-722, Boston, MA 02114
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23
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Peters JM, Gonzalez FJ. Sorting out the functional role(s) of peroxisome proliferator-activated receptor-beta/delta (PPARbeta/delta) in cell proliferation and cancer. Biochim Biophys Acta Rev Cancer 2009; 1796:230-41. [PMID: 19505534 DOI: 10.1016/j.bbcan.2009.06.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 06/01/2009] [Accepted: 06/02/2009] [Indexed: 12/19/2022]
Abstract
Peroxisome proliferator-activated receptor-beta/delta (PPARbeta/delta) has many beneficial physiological functions ranging from enhancing fatty acid catabolism, improving insulin sensitivity, inhibiting inflammation and increasing oxidative myofibers allowing for improved athletic performance. Thus, given the potential for targeting PPARbeta/delta for the prevention and/or treatment of diseases including diabetes, dyslipidemias, metabolic syndrome and cancer, it is critical to clarify the functional role of PPARbeta/delta in cell proliferation and associated disorders such as cancer. However, there is considerable controversy whether PPARbeta/delta stimulates or inhibits cell proliferation. This review summarizes the literature describing the influence of PPARbeta/delta on cell proliferation, with an emphasis toward dissecting the data that give rise to opposing hypotheses. Suggestions are offered to standardize measurements associated with these studies so that interlaboratory comparisons can be accurately assessed.
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Affiliation(s)
- Jeffrey M Peters
- Department of Veterinary and Biomedical Sciences and The Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA 16802, USA.
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Role of peroxisome-proliferator-activated receptor beta/delta (PPARbeta/delta) in gastrointestinal tract function and disease. Clin Sci (Lond) 2008; 115:107-27. [PMID: 18616431 DOI: 10.1042/cs20080022] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PPARbeta/delta (peroxisome-proliferator-activated receptor beta/delta) is one of three PPARs in the nuclear hormone receptor superfamily that are collectively involved in the control of lipid homoeostasis among other functions. PPARbeta/delta not only acts as a ligand-activated transcription factor, but also affects signal transduction by interacting with other transcription factors such as NF-kappaB (nuclear factor kappaB). Constitutive expression of PPARbeta/delta in the gastrointestinal tract is very high compared with other tissues and its potential physiological roles in this tissue include homoeostatic regulation of intestinal cell proliferation/differentiation and modulation of inflammation associated with inflammatory bowel disease and colon cancer. Analysis of mouse epithelial cells in the intestine and colon has clearly demonstrated that ligand activation of PPARbeta/delta induces terminal differentiation. The PPARbeta/delta target genes mediating this effect are currently unknown. Emerging evidence suggests that PPARbeta/delta can suppress inflammatory bowel disease through PPARbeta/delta-dependent and ligand-independent down-regulation of inflammatory signalling. However, the role of PPARbeta/delta in colon carcinogenesis remains controversial, as conflicting evidence suggests that ligand activation of PPARbeta/delta can either potentiate or attenuate this disease. In the present review, we summarize the role of PPARbeta/delta in gastrointestinal physiology and disease with an emphasis on findings in experimental models using both high-affinity ligands and null-mouse models.
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