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Søreide K. Bacterial genotoxins, gene methylation, and RNA interference: pointing to colorectal cancer as an infectious disease? Scand J Gastroenterol 2009; 43:1529-33. [PMID: 18654935 DOI: 10.1080/00365520802272134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Kjetil Søreide
- Department of Surgery, Stavanger University Hospital, Stavanger, Norway.
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152
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Peters U, Takata Y. Selenium and the prevention of prostate and colorectal cancer. Mol Nutr Food Res 2009; 52:1261-72. [PMID: 18763256 DOI: 10.1002/mnfr.200800103] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Prostate and colorectal cancers are among the most common cancers and identifying modifiable risk factors are important steps to reduce the burden of these severe diseases. Results from several but mostly small observational studies as well as the secondary analysis of an intervention trial provide support for a chemopreventive effect of selenium on prostate and colorectal cancers. Results suggest effect modification by gender and smoking, but this interpretation is limited by the statistical power of previous studies. Several cancer preventive mechanisms have been described and it is likely that selenium acts through multiple pathways. In particular, the anti-oxidative and anti-inflammatory effects mediated through activity of selenoenzymes are discussed, given the relevance of oxidative stress and inflammation in these cancers. Genetic variation in selenoenzymes may modify the potential chemopreventive effect of selenium and need to be further investigated. Additional large observational studies using biomarkers of selenium intake and intervention trials, such as the Selenium and Vitamin E Cancer Prevention Trial, will be important to further evaluate the potential chemopreventive effect of selenium. Furthermore, characterization of functional effects of polymorphisms in selenoenzymes is needed.
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Affiliation(s)
- Ulrike Peters
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA 98109-1024, USA.
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153
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Payne CM, Bernstein C, Dvorak K, Bernstein H. Hydrophobic bile acids, genomic instability, Darwinian selection, and colon carcinogenesis. Clin Exp Gastroenterol 2008; 1:19-47. [PMID: 21677822 PMCID: PMC3108627 DOI: 10.2147/ceg.s4343] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Sporadic colon cancer is caused predominantly by dietary factors. We have selected bile acids as a focus of this review since high levels of hydrophobic bile acids accompany a Western-style diet, and play a key role in colon carcinogenesis. We describe how bile acid-induced stresses cause cell death in susceptible cells, contribute to genomic instability in surviving cells, impose Darwinian selection on survivors and enhance initiation and progression to colon cancer. The most likely major mechanisms by which hydrophobic bile acids induce stresses on cells (DNA damage, endoplasmic reticulum stress, mitochondrial damage) are described. Persistent exposure of colon epithelial cells to hydrophobic bile acids can result in the activation of pro-survival stress-response pathways, and the modulation of numerous genes/proteins associated with chromosome maintenance and mitosis. The multiple mechanisms by which hydrophobic bile acids contribute to genomic instability are discussed, and include oxidative DNA damage, p53 and other mutations, micronuclei formation and aneuploidy. Since bile acids and oxidative stress decrease DNA repair proteins, an increase in DNA damage and increased genomic instability through this mechanism is also described. This review provides a mechanistic explanation for the important link between a Western-style diet and associated increased levels of colon cancer.
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Affiliation(s)
- Claire M Payne
- Department of Cell Biology and Anatomy, College of Medicine, University of Arizona, Tucson, Arizona, USA
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154
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Wang X, Allen TD, May RJ, Lightfoot S, Houchen CW, Huycke MM. Enterococcus faecalis induces aneuploidy and tetraploidy in colonic epithelial cells through a bystander effect. Cancer Res 2008; 68:9909-17. [PMID: 19047172 PMCID: PMC2596646 DOI: 10.1158/0008-5472.can-08-1551] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Intestinal commensals are potential important contributors to the etiology of sporadic colorectal cancer, but mechanisms by which bacteria can initiate tumors remain uncertain. Herein, we describe mechanisms that link Enterococcus faecalis, a bacterium known to produce extracellular superoxide, to the acute induction of chromosomal instability. Immortalized human and nontransformed murine colonic epithelial cells, along with a mouse colonic ligation model, were used to assess the effect of E. faecalis on genomic DNA stability and damage. We found that this human intestinal commensal generated aneuploidy, tetraploidy, and gammaH2AX foci in HCT116, RKO, and YAMC cells. In addition, direct exposure of E. faecalis to these cells induced a G2 cell cycle arrest. Similar observations were noted by exposing cells to E. faecalis-infected macrophages in a dual-chamber coculture system for detecting bystander effects. Manganese superoxide dismutase, catalase, and tocopherols attenuated, and caffeine and inhibitors of glutathione synthase exacerbated, the aneugenic effects and linked the redox-active phenotype of this intestinal commensal to potentially transforming events. These findings provide novel insights into mechanisms by which E. faecalis and intestinal commensals can contribute to cellular transformation and tumorigenesis.
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Affiliation(s)
- Xingmin Wang
- The Muchmore Laboratories for Infectious Diseases Research, Research Service, Department of Veterans Affairs Medical Center, Oklahoma City, OK, 73104 USA
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104 USA
| | - Toby D. Allen
- The Muchmore Laboratories for Infectious Diseases Research, Research Service, Department of Veterans Affairs Medical Center, Oklahoma City, OK, 73104 USA
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104 USA
| | - Randal J. May
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104 USA
| | - Stanley Lightfoot
- Departments of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104 USA
| | - Courtney W. Houchen
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104 USA
| | - Mark M. Huycke
- The Muchmore Laboratories for Infectious Diseases Research, Research Service, Department of Veterans Affairs Medical Center, Oklahoma City, OK, 73104 USA
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104 USA
- Reprints: Mark M. Huycke Medical Service (111) Dept. of Veterans Affairs Medical Center 921 NE 13 Street Oklahoma City, OK 73104 E-mail:
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155
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Allen TD, Moore DR, Wang X, Casu V, May R, Lerner MR, Houchen C, Brackett DJ, Huycke MM. Dichotomous metabolism of Enterococcus faecalis induced by haematin starvation modulates colonic gene expression. J Med Microbiol 2008; 57:1193-1204. [PMID: 18809545 DOI: 10.1099/jmm.0.47798-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Enterococcus faecalis is an intestinal commensal that cannot synthesize porphyrins and only expresses a functional respiratory chain when provided with exogenous haematin. In the absence of haematin, E. faecalis reverts to fermentative metabolism and produces extracellular superoxide that can damage epithelial-cell DNA. The acute response of the colonic mucosa to haematin-starved E. faecalis was identified by gene array. E. faecalis was inoculated into murine colons using a surgical ligation model that preserved tissue architecture and homeostasis. The mucosa was exposed to haematin-starved E. faecalis and compared with a control consisting of the same strain grown with haematin. At 1 h post-inoculation, 6 mucosal genes were differentially regulated and this increased to 42 genes at 6 h. At 6 h, a highly significant biological interaction network was identified with functions that included nuclear factor-kappaB (NF-kappaB) signalling, apoptosis and cell-cycle regulation. Colon biopsies showed no histological abnormalities by haematoxylin and eosin staining. Immunohistochemical staining, however, detected NF-kappaB activation in tissue macrophages using antibodies to the nuclear localization sequence for p65 and the F4/80 marker for murine macrophages. Similarly, haematin-starved E. faecalis strongly activated NF-kappaB in murine macrophages in vitro. Furthermore, primary and transformed colonic epithelial cells activated the G2/M checkpoint in vitro following exposure to haematin-starved E. faecalis. Modulation of this cell-cycle checkpoint was due to extracellular superoxide produced as a result of the respiratory block in haematin-starved E. faecalis. These results demonstrate that the uniquely dichotomous metabolism of E. faecalis can significantly modulate gene expression in the colonic mucosa for pathways associated with inflammation, apoptosis and cell-cycle regulation.
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Affiliation(s)
- Toby D Allen
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.,Muchmore Laboratories for Infectious Disease Research, Department of Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
| | - Danny R Moore
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.,Muchmore Laboratories for Infectious Disease Research, Department of Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
| | - Xingmin Wang
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.,Muchmore Laboratories for Infectious Disease Research, Department of Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
| | - Viviana Casu
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.,Muchmore Laboratories for Infectious Disease Research, Department of Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
| | - Randal May
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Megan R Lerner
- Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Courtney Houchen
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Daniel J Brackett
- Research Service, Department of Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA.,Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Mark M Huycke
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.,Muchmore Laboratories for Infectious Disease Research, Department of Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
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156
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Tasso R, Augello A, Carida' M, Postiglione F, Tibiletti MG, Bernasconi B, Astigiano S, Fais F, Truini M, Cancedda R, Pennesi G. Development of sarcomas in mice implanted with mesenchymal stem cells seeded onto bioscaffolds. Carcinogenesis 2008; 30:150-7. [PMID: 18849298 DOI: 10.1093/carcin/bgn234] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bone marrow-derived mesenchymal stem cells (MSCs) are precursors of bone, cartilage and fat tissue. MSC can also regulate the immune response. For these properties, they are tested in clinical trials for tissue repair in combination with bioscaffolds or injected as cell suspension for immunosuppressant therapy. Experimental data, however, indicate that MSC can undergo or induce a tumorigenic process in determined circumstances. We used a modified model of ectopic bone formation in mice by subcutaneously implanting porous ceramic seeded with murine MSC. In this new model, host-derived sarcomas developed when we implanted MSC/bioscaffold constructs into syngeneic and immunodeficient recipients, but not in allogeneic hosts or when MSCs were injected as cell suspensions. The bioscaffold provided a tridimensional support for MSC to aggregate, thus producing the stimulus for triggering the process eventually leading to the transformation of surrounding cells and creating a surrogate tumor stroma. The chemical and physical characteristics of the bioscaffold did not affect tumor formation; sarcomas developed either when a stiff porous ceramic was used or when the scaffold was a smooth collagen sponge. The immunoregulatory function of MSC contributed to tumor development. Implanted MSC expanded clones of CD4+CD25+ T regulatory lymphocytes that suppressed host's antitumor immune response.
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Affiliation(s)
- Roberta Tasso
- Department of Oncology, Biology and Genetics, University of Genova, Genova, Italy
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157
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Peters U, Chatterjee N, Hayes RB, Schoen RE, Wang Y, Chanock SJ, Foster CB. Variation in the selenoenzyme genes and risk of advanced distal colorectal adenoma. Cancer Epidemiol Biomarkers Prev 2008; 17:1144-54. [PMID: 18483336 DOI: 10.1158/1055-9965.epi-07-2947] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Epidemiologic and animal studies provide evidence for a chemopreventive effect of selenium on colorectal cancer, which may be mediated by the antioxidative and anti-inflammatory properties of selenoenzymes. We therefore investigated whether genetic variants in selenoenzymes abundantly expressed in the colon are associated with advanced colorectal adenoma, a cancer precursor. METHODS Cases with a left-sided advanced adenoma (n = 772) and matched controls (n = 777) screen negative for polyps based on sigmoidoscopy examination were randomly selected from participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The underlying genetic variation was determined by resequencing. We genotyped 44 tagging single nucleotide polymorphisms (SNP) in six genes [glutathione peroxidase 1-4 (GPX1, GPX2, GPX3, and GPX4), selenoprotein P (SEPP1), and thioredoxin reductase 1 (TXNRD1)] to efficiently predict common variation across these genes. RESULTS Four variants in SEPP1 were significantly associated with advanced adenoma risk. A rare variant in the 5' region of SEPP1 (-4166C>G) was present in nine cases but in none of the controls (exact P = 0.002). Three SNPs located in the 3' region of SEPP1, which is overlapping with the promoter region of an antisense transcript, were significantly associated with adenoma risk: homozygotes at two SEPP1 loci (31,174 bp 3' of STP A>G and 43,881 bp 3' of STP G>A) were associated with increased adenoma risk [odds ratio (OR), 1.48; 95% confidence interval (95% CI), 1.00-2.19 and OR, 1.53; 95% CI, 1.05-2.22, respectively] and the variant SEPP1 44,321 bp 3' of STP C>T was associated with a reduced adenoma risk (CT versus CC OR, 0.85; 95% CI, 0.63-1.15). Furthermore, we observed a significant 80% reduction for advanced colorectal adenoma risk for carriers of the variant allele at TXNRD1 IVS1-181C>G (OR, 0.20; 95% CI, 0.07-0.55; P trend = 0.004). Consistent with the individual SNP results, we observed a significant overall association with adenoma risk for SEPP1 and TXNRD1 (global P = 0.02 and 0.008, respectively) but not for the four GPX genes. CONCLUSION Our study suggests that genetic variants at or near the SEPP1 and TXNRD1 loci may be associated with advanced colorectal adenoma. As this is the first study to comprehensively investigate this hypothesis, confirmation in independent study populations is needed.
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Affiliation(s)
- Ulrike Peters
- Public Health Science, Fred Hutchinson Cancer Research Center, PO Box 19024, Seattle, WA 98109-1024, USA.
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158
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Balamurugan R, Rajendiran E, George S, Samuel GV, Ramakrishna BS. Real-time polymerase chain reaction quantification of specific butyrate-producing bacteria, Desulfovibrio and Enterococcus faecalis in the feces of patients with colorectal cancer. J Gastroenterol Hepatol 2008; 23:1298-303. [PMID: 18624900 DOI: 10.1111/j.1440-1746.2008.05490.x] [Citation(s) in RCA: 218] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIM Bacterial metabolites produced in the bowel are potentially related to the genesis of colorectal cancer. Butyrate is protective against cancer, whereas hydrogen sulfide and oxygen free radicals can be toxic to the epithelium. The present study was designed to quantitate Eubacterium rectale, Faecalibacterium prausnitzii (both butyrate-producing bacteria), Desulfovibrio (sulfate-reducing bacteria), and Enterococcus faecalis (that produces extracellular superoxide) in the feces of patients with colorectal cancer. METHODS DNA was extracted from feces of 20 patients with colorectal cancer, nine patients with upper gastrointestinal cancer and 17 healthy volunteers. Real-time polymerase chain reaction using primers aimed at 16S rDNA was used to quantitate the above bacterial species or genus, and this was expressed relative to amplification of universal sequences conserved among all bacteria. RESULTS Levels of E. rectale and F. prausnitzii were decreased approximately fourfold (P = 0.0088 and 0.0028, respectively) in colorectal cancer patients compared to healthy control volunteers. Levels of Desulfovibrio were not significantly different between the three groups. E. faecalis populations were significantly higher in colorectal cancer patients compared to healthy volunteers (P = 0.0294). CONCLUSIONS Butyrate producers were decreased and E. faecalis increased in the feces of colon cancer patients. These shifts in the colonic bacterial population could potentially lead to epithelial cell damage and increased turnover and may be a factor leading to colon cancer.
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Affiliation(s)
- Ramadass Balamurugan
- The Wellcome Trust Research Laboratory, Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India
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159
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Semino-Mora C, Liu H, McAvoy T, Nieroda C, Studeman K, Sardi A, Dubois A. Pseudomyxoma peritonei: is disease progression related to microbial agents? A study of bacteria, MUC2 AND MUC5AC expression in disseminated peritoneal adenomucinosis and peritoneal mucinous carcinomatosis. Ann Surg Oncol 2008; 15:1414-23. [PMID: 18299935 PMCID: PMC2570966 DOI: 10.1245/s10434-007-9778-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 12/01/2007] [Accepted: 12/03/2007] [Indexed: 12/27/2022]
Abstract
BACKGROUND AND AIMS Pseudomyxoma peritonei (PMP) is characterized by peritoneal tumors arising from a perforated appendiceal adenoma or adenocarcinoma, but associated entry of enteric bacteria in the peritoneum has not been considered as a cofactor. Because Gram-negative organisms can upregulate MUC2 mucin gene expression, we determined whether bacteria were detectable in PMP tissues. METHODS In situ hybridization was performed on resection specimens from five control subjects with noninflamed, nonperforated, non-neoplastic appendix and 16 patients with PMP [six with disseminated peritoneal adenomucinosis (DPAM) and 10 with peritoneal mucinous carcinomatosis (PMCA)]. Specific probes were designed to recognize: (1) 16S rRNA common to multiple bacteria or specific to H. pylori; (2) H. pylori cagA virulence gene; or (3) MUC2 or MUC5AC apomucins. Specimens from one patient with PMCA were examined by ultrastructural immunohistochemistry. Bacterial density and apomucin expression were determined in four histopathological compartments (epithelia, inflammatory cells, stroma, and free mucus). RESULTS Enteric bacteria were detected in all specimens. Bacterial density and MUC2 expression were significantly (p < 0.05) higher in PMCA than in DPAM and controls and were highest in free mucin. MUC2 was also expressed in dysplastic epithelia and in associated inflammatory cells. MUC2 expression was significantly correlated with bacterial density. CONCLUSIONS Multiple enteric bacteria are present in PMP, and bacterial density and MUC2 expression is highest in the malignant form of PMP. Based on these observations, we propose that the bacteria observed in PMP may play a role in the mucinous ascites and perhaps promote carcinogenesis.
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Affiliation(s)
- Cristina Semino-Mora
- Laboratory of Gastrointestinal and Liver Studies, Department of Medicine, Uniformed Services University and United States Military Cancer Institute, Bethesda, MD 20814, USA
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160
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Abstract
Mounting evidence supports the tenet that innate immune responses to luminal microbes participate in the development of gastrointestinal malignancies. The gastrointestinal tract is relatively unique in that it has evolved in the presence of diverse enteric microflora. Intestinal flora is required to develop a normal adaptive immune response in the periphery. With the characterization of the innate immune system, we have begun to understand the adaptations the intestine has made to the microbiota. The interaction between the microbiota and the intestinal mucosa through Toll-like receptors (TLRs) is required to maintain intestinal homeostasis. In particular, intestinal epithelial cells and lamina propria mononuclear cells such as antigen-presenting cells and T cells must respond to breaches in the mucosal barrier by activating TLR-dependent pathways that result in increased epithelial proliferation, wound healing and recruitment of acute inflammatory cells. In the setting of chronic inflammation such as Helicobacter pylori (H. pylori) infection in the stomach or idiopathic inflammatory bowel disease, the process of repair may eventually result in carcinogenesis. The following review highlights human and animal data that support a role for innate immune responses and TLRs specifically in promoting gastrointestinal malignancies. Candidate pathways linking TLRs to gastrointestinal malignancies include activation of nuclear factor-kappaB and cyclooxygenase-2. Studying the link between innate immune signaling and gastrointestinal malignancies offers the possibility to identify novel ways to both prevent and treat gastrointestinal cancer.
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Affiliation(s)
- M Fukata
- Inflammatory Bowel Disease Center, Division of Gastroenterology, Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
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161
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Fukata M, Chen A, Vamadevan AS, Cohen J, Breglio K, Krishnareddy S, Xu R, Harpaz N, Dannenberg AJ, Subbaramaiah K, Cooper HS, Itzkowitz SH, Abreu MT, Abreu MT. Toll-like receptor-4 promotes the development of colitis-associated colorectal tumors. Gastroenterology 2007; 133:1869-81. [PMID: 18054559 PMCID: PMC2180834 DOI: 10.1053/j.gastro.2007.09.008] [Citation(s) in RCA: 486] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 08/30/2007] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Chronic inflammation is a risk factor for colon cancer in patients with ulcerative colitis (UC). The molecular mechanisms linking inflammation and colon carcinogenesis are incompletely understood. We tested the hypothesis that Toll-like receptor 4 (TLR4) is involved in tumorigenesis in the setting of chronic inflammation. METHODS Tissues from UC patients with cancer were examined for TLR4 expression. Colitis-associated neoplasia was induced using azoxymethane injection followed by dextran sodium sulfate treatment in TLR4-deficient or wild-type mice. Inflammation, polyps, and microscopic dysplasia were scored. Cyclooxygenase (Cox)-2 and prostaglandin E(2) production were analyzed by real-time polymerase chain reaction, immunohistochemistry, or enzyme immunoassay. Epidermal growth factor receptor (EGFR) phosphorylation and amphiregulin production were examined by Western blot analysis and enzyme-linked immunosorbent assay, respectively. RESULTS We show that TLR4 is overexpressed in human and murine inflammation-associated colorectal neoplasia. TLR4-deficient mice were protected markedly from colon carcinogenesis. Mechanistically, we show that TLR4 is responsible for induction of Cox-2, increased prostaglandin E(2) production, and activation of EGFR signaling in chronic colitis. Amphiregulin, an EGFR ligand, was induced in a TLR4, Cox-2-dependent fashion and contributes to activation of EGFR phosphorylation in colonic epithelial cells. CONCLUSIONS TLR4 signaling is critical for colon carcinogenesis in chronic colitis. TLR4 activation appears to promote the development of colitis-associated cancer by mechanisms including enhanced Cox-2 expression and increased EGFR signaling. Inhibiting TLR4 signaling may be useful in the prevention or treatment of colitis-associated cancer.
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Affiliation(s)
- Masayuki Fukata
- Inflammatory Bowel Disease Center, Mount Sinai School of Medicine, New York, New York
| | - Anli Chen
- Inflammatory Bowel Disease Center, Mount Sinai School of Medicine, New York, New York
| | - Arunan S. Vamadevan
- Inflammatory Bowel Disease Center, Mount Sinai School of Medicine, New York, New York
| | - Jason Cohen
- Inflammatory Bowel Disease Center, Mount Sinai School of Medicine, New York, New York
| | - Keith Breglio
- Inflammatory Bowel Disease Center, Mount Sinai School of Medicine, New York, New York
| | - Suneeta Krishnareddy
- Inflammatory Bowel Disease Center, Mount Sinai School of Medicine, New York, New York
| | - Ruliang Xu
- Department of Pathology, Mount Sinai School of Medicine, New York, New York
| | - Noam Harpaz
- Department of Pathology, Mount Sinai School of Medicine, New York, New York
| | - Andrew J. Dannenberg
- Department of Medicine, Division of Gastroenterology and Hepatology, New York Presbyterian Hospital and Weill Medical College of Cornell University, New York, New York
| | - Kotha Subbaramaiah
- Department of Medicine, Division of Gastroenterology and Hepatology, New York Presbyterian Hospital and Weill Medical College of Cornell University, New York, New York
| | - Harry S. Cooper
- Department of Pathology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Steven H. Itzkowitz
- Division of Gastroenterology, Department of Medicine, Mount Sinai School of Medicine, New York, New York
| | - Maria T. Abreu
- Inflammatory Bowel Disease Center, Mount Sinai School of Medicine, New York, New York
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