Development Of Colonic Neoplasia Research Articles

Mechanisms of Immune Signaling in Colitis-Associated Cancer

The inflammatory bowel diseases ulcerative colitis and Crohn’s disease are associated with an increased risk for the development of colorectal cancer. During recent years, several immune signaling pathways have been linked to colitis-associated cancer (CAC), largely owing to the availability of suitable preclinical models. Among these, chronic intestinal inflammation has been shown to support tumor initiation through oxidative stress–induced mutations. A proinflammatory microenvironment that develops, possibly as a result of defective intestinal barrier function and host–microbial interactions, enables tumor promotion. Several molecular pathways such as tumor necrosis factor/nuclear factor-κB or interleukin 6/signal transducer and activator of transcription 3 signaling have been identified as important contributors to CAC development and could be promising therapeutic targets for the prevention and treatment of CAC.

Mo1767 Genetic Deletion of IL-25 Increases Susceptibility to High-Fat Diet-Induced Metabolic Dysfunction in Mice

unknown. This study therefore evaluated the effect of the DPP-4 inhibitor, sitagliptin (STG), on diabetes-related colon carcinogenesis in mice. Materials and Methods: Six-week-old male wild-type (WT) and leptin-deficient (ob/ob) C57BL/6J mice were used in this study. The mice received 1,2-dimethlhydrazine (DMH) subcutaneously at a dose of 20 mg/kg body weight three times within a week, and chronic colitis was then induced by administration of two cycles of DSS (each cycle: 3% DSS for 7 days followed by distilled water for 14 days). Sitagliptin (3 mg/kg) was administered to the mice by oral gavage every day during the entire experimental period. The mice were divided into the following three groups: WT group; obob group; and obob+STG group. The mice were sacrificed 28 days after the completion of both cycles of DSS. Results: During the DSS administration cycle, mean body weight decreased significantly in the WT group compared with the obob and obob+STG groups. The disease activity index (DAI) was also increased significantly in the WT group. However, administration of STG did not affect the DAI or body weight. The mean number of tumors was 7.8±4.5, 10.6±3.3, and 6.7±2.4 in the WT, obob, and obob+STG groups, respectively. STG significantly suppressed the occurrence of neoplasia in the obob mice. Mucosal DPP-4 activity and the mucosal concentration of GLP-2 were not significantly different in the three groups. Conclusion: Administration of STG exerts a suppressive effect on the development of colon neoplasia in a murine model of type 2 diabetes. However, STG does not affect the mucosal DPP-4 activity. Because DPP-4 mRNA/DPP-4 activity are highly expressed/detected in the small intestine andDPP-8 and 9 are expressed predominantly in the colon, DPP-4 inhibitors may suppress colon carcinogenesis independent of the GLP pathway.

Abstract 3710: Targeted inhibition of arginase-1 may underline the suppression of the development of colonic neoplasia in a transgenic APC Min mouse model.

Abstract Colorectal cancer (CRC) is the third-leading malignancy in the United States. This year alone, about 141,210 new cases of colorectal cancer will be diagnosed and more than 49,380 people will die from the disease. Strategies have focused on early screening practices and the prevention of the development of colonic adenomas that serve as precursors of invasive colon cancers. We have recently showed that chloroquine (CQ) an anti-malarial and anti-rheumatoid agent has the capacity to competitively inhibit intracellular arginase-1 (ARG-1) and that this inhibition increases the nuclear localization of the cell cycle regulator p53 protein in colon cancer cell lines. However, the mechanism of CQ-induced inhibition of ARG-1 that results in the up-regulation of p53 is unclear. The goal of the current study was to examine the chemopreventive efficacy of CQ in the development of colonic neoplasia and to further evaluate the possible mechanism(s) of action. In this regard, six weeks old Apc(Min/+) mice were treated daily (except Saturdays and Sundays) with 0-50 mg CQ/kg body wt. via oral gavage for forty days. Post-treatment, mice were sacrificed and jejunum and colon were retrieved and preserved in 10% formalin for observation of any gross pathological changes. The results of this study showed an increased in prevalence of colonic adenomas in untreated mice compared with treated mice (< 0.05). Interestingly, histochemical analysis showed significant numbers of adenomas with high-grade dysplasia (as evidenced by the presence of increased fibrous tissue core) in untreated control mice in comparison with drug-treated mice (<0.05).Since emerging studies have identified the overexpression of ARG-1 in a variety of human malignancies, including cancer of the colon, we then investigated the impact of CQ on ARG-1 levels. To this end, HT-29 cells were co-incubated with CQ (0-50 μM) for 24 h and the levels of ARG-1 were determined by western blot assay. Surprisingly, our result showed that CQ-induced inhibition of ARG-1 level corresponded to the diminution of β-catenin protein via to its phosphorylation. Further immuno- fluorescence analysis showed an increased level of nuclear localization of GFP tagged p53 (GFP-p53) and p21 in transiently transfected HT-29 cells upon CQ treatment. The observation that targeting ARG-1 results in a corresponding decrease in β-catenin level is intriguing, since the Wnt/β-catenin signaling is fundamental to colon carcinogenesis and spontaneous tumorigenesis in Apc(Min/+) mice and patients with familial adenomatous polyposis.In conclusion, our cumulative findings indicate that CQ ameliorates the development of colonic neoplasia and that the inhibition of ARG-1 and β-catenin may contribute to its chemopreventive effects in intestinal tumorigenesis. Citation Format: Efe W. Iyamu, Mohammad S. Niaz, Aramandla Ramesh, Amos Sakwe, Kieosha Williams, Billy R. Ballard, Samuel E. Adunyah. Targeted inhibition of arginase-1 may underline the suppression of the development of colonic neoplasia in a transgenic APC Min mouse model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3710. doi:10.1158/1538-7445.AM2013-3710

Abstract 163: Common food additive carrageenan activates wnt signaling pathway in mouse colon and human colonic epithelial cells

Abstract The Wnt-β-catenin signaling pathway plays a pivotal role in development and disease. It is crucial for basic developmental processes, such as cell-fate specification, progenitor-cell proliferation and the control of asymmetric cell division. Recent studies suggest that self-renewal of stem/progenitor cells by the canonical Wnt cascade is subverted in cancer cells to allow malignant proliferation in intestine. Carrageenans are highly sulfated polysaccharides, which are widely used as food additives to improve the texture of processed foods, and are consumed at levels of about 250 mg/day in the average diet. Reports of many investigators have demonstrated that carrageenan induces inflammation, colonic ulcerations, polyps, and colorectal tumors. We have reported distinct pathways by which carrageenan induces the activation of NF-κB and secretion of IL-8, mediated through TLR4-BCL10 or reactive oxygen species (ROS) in colonic epithelial cells. Our previous work also indicated that carrageenan exposure caused activation of the Wnt-β-catenin pathway in colonic epithelial cells. This investigation was undertaken to elucidate the Wnt signaling mechanisms activated by carrageenan exposure, using NCM460 (INCELL) human colonic epithelial cells exposed to carrageenan (1 μg/ml) x 24 h and colonic tissue from ten-week old C57BL/6J mice exposed to carrageenan (10 - 100 μg/ml) in their water for four weeks. Nuclear β-catenin in NCM460 cells and mouse colonic tissue was determined by Western blot and ELISA and increased to two times the baseline level following carrageenan. This increase in nuclear β-catenin in NCM460 cells was inhibited by the ROS quencher Tempol, but not by TLR4 or BCL10 siRNA. TCF/Lef-1 reporter assay demonstrated increased nuclear binding post carrageenan treatment in the mouse colon (to 4x baseline) and in the NCM460 cells (to 6.3x baseline). Also, mRNA expression of cyclin D1 and wnt9a was increased more than two-fold, and BMP4 expression was decreased. In the NCM460 cells, these responses to carrageenan were inhibited by Tempol, but not BCL10 silencing. Also, carrageenan-induced increases in ROS and lipid peroxidation were inhibited by Tempol. Since Wnt signaling is affected by free dishevelled 2 (dsh2), and dsh2 binding to nucleoredoxin (NRX) is greater when NRX is in its reduced state, we tested whether carrageenan exposure could impact upon the Wnt signaling pathway by modifying the redox status of NRX. The ratio of free NRX to NRX bound to dsh2 increased to six times baseline following carrageenan, and was reversed by Tempol. These profound effects of carrageenan on the Wnt signaling pathway in colonic cells can help to explain how diet can contribute to development of colonic neoplasia. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 163. doi:1538-7445.AM2012-163

Racial differences in measures of obesity and risk of colon adenoma.

Obesity is an established risk factor for several malignancies. However, the specific measurement of obesity most relevant to colon neoplasia is still debated, and evidence has suggested gender and racial differences in this measurement. In this study, we sought to compare which measurement--BMI, waist circumference (WC), waist-to-hip ratio (WHR) or waist-to-height ratio (WHtR)--is most strongly associated with development of colon adenomas, a precursor of colon cancer, and to investigate differences in this association between racial groups. We confirmed the strong association between WHR, as a measure of central obesity, and development of colon neoplasia. In our overall analysis, patients in the highest WHR quartile showed a substantial increase in risk of colon adenomas compared to patients in the lowest WHR quartile (odds ratio (OR) = 1.82, 95% confidence interval (CI): 1.12-2.71, P(trend) = 0.0017). In stratified analyses, we noted that strongly associated obesity measures in European Americans were WC (OR = 2.38, 95% CI = 1.45-3.92, P(trend) = 0.0004) and BMI (OR = 2.18, 95% CI = 1.37-3.49, P(trend) = 0.0015), whereas in African Americans, WHR was the strongest and the only obesity measure statistically significantly associated with adenoma risk (OR = 2.12, 95% CI = 1.05-4.30, P(trend) = 0.025). Our data highlight the importance of obesity in the development of early colon neoplasia and suggest substantial racial differences in the measures of obesity most strongly associated with risk of colon adenomas.

Lifelong genistein feeding reduces colon neoplasia by affecting the expression profile of WNT signaling in AOM‐treated rats

Colon cancer is a leading cancer worldwide. We investigated the effects of genistein (GEN) and soy protein isolate on the development of colon neoplasia in azoxymethane (AOM)-induced rats. Male Sprague-Dawley rats were exposed to a control (0 mg/kg of GEN), soy protein isolate (SPI, contains 140 mg/kg of GEN, aglycone equivalent), or genistein (140 mg/kg) diet throughout life, including gestation, lactation, and after weaning until the end of the study. Colon samples were collected at 6 w of age and analyzed for the baseline profile. The rest of rats were induced by AOM injection at 7 w of age and colon samples were collected at 13 w of age. Numbers of aberrant crypt foci (ACF) was determined in the descending colon. Offspring from all three dietary groups developed ACF. GEN and SPI diets decreased the numbers of total ACF/cm of colon, especially the numbers of higher multiplicity ACF/cm. Nuclear β-catenin level was not different between three diet groups at 6 w. However, SPI and GEN repressed AOM-induced Nuclear β-catenin accumulation at 13 w. Moreover, SPI and GEN maintained lower expression of WNT signaling including Wnt1, Wnt5a and WNT antagonists sFRP1, sFRP2 and sFRP5 compared to control after AOM treatment. Our results suggest that lifelong exposure to genistein reduces descending colon neoplasia by affecting WNT signaling and suppressing β-catenin accumulation in the AOM-induced rat model. Grant Funding Source: NIH

The role of gut microbiota (commensal bacteria) and the mucosal barrier in the pathogenesis of inflammatory and autoimmune diseases and cancer: contribution of germ-free and gnotobiotic animal models of human diseases.

Metagenomic approaches are currently being used to decipher the genome of the microbiota (microbiome), and, in parallel, functional studies are being performed to analyze the effects of the microbiota on the host. Gnotobiological methods are an indispensable tool for studying the consequences of bacterial colonization. Animals used as models of human diseases can be maintained in sterile conditions (isolators used for germ-free rearing) and specifically colonized with defined microbes (including non-cultivable commensal bacteria). The effects of the germ-free state or the effects of colonization on disease initiation and maintenance can be observed in these models. Using this approach we demonstrated direct involvement of components of the microbiota in chronic intestinal inflammation and development of colonic neoplasia (i.e., using models of human inflammatory bowel disease and colorectal carcinoma). In contrast, a protective effect of microbiota colonization was demonstrated for the development of autoimmune diabetes in non-obese diabetic (NOD) mice. Interestingly, the development of atherosclerosis in germ-free apolipoprotein E (ApoE)-deficient mice fed by a standard low-cholesterol diet is accelerated compared with conventionally reared animals. Mucosal induction of tolerance to allergen Bet v1 was not influenced by the presence or absence of microbiota. Identification of components of the microbiota and elucidation of the molecular mechanisms of their action in inducing pathological changes or exerting beneficial, disease-protective activities could aid in our ability to influence the composition of the microbiota and to find bacterial strains and components (e.g., probiotics and prebiotics) whose administration may aid in disease prevention and treatment.

S2050 Prostanglandin E2 Receptors Are Involved in Nicotine-Induced Gastric Tumor Growth

We have previously determined that the small GTPase Rab25 regulates membrane recycling in epithelial cells. However, little is known whether membrane recycling and vesicle trafficking pathways influence epithelial tissue transformation and neoplasia. Based on the hypothesis that membrane recycling is necessary to maintain epithelial cell polarity, we sought to determine the effects of Rab25 loss on the development of colonic neoplasia. We therefore bred Rab25 knockout mice in the C57BL/6 background onto the ApcMin/+ mouse. To understand the function of Rab25, we have developed a mouse model for deletion of the Rab25 gene product. To assess the effects of Rab25 loss on the development of colonic neoplasia, we have bred Rab25 knockout mice on the C57BL/6 background onto the ApcMin/ +mouse. At 4months of age, Rab25-/-ApcMin/+mice showed 175 intestinal polyps compared with 45.4 in Rab25+/+ApcMin/+ mice and 98.5 in Rab25+/-ApcMin/+ mice (p<0.01). In the colon, Rab25-/-ApcMin/+ 4.7 colon tumors compared with only 1.9 in Rab25+/+ApcMin/ + mice (p<0.01) and 3.5 in Rab25+/-ApcMin/+ mice. Histopathological analysis of the polyps in Rab25-/-ApcMin/+ mice showed diffuse and fused microadenomas with high mitotic index compared to control. We also sought to examine Rab25 gene expression in a large panel of colon cancer tumor isolates by mining a previously characterized series of mouse and human tumor gene microarray expression profile data. Expression of Rab25 was significantly decreased in colon adenocarcinomas (p<0.03) independent of Duke's stage. In addition, Kaplan-Meier analysis demonstrated that lower expression of Rab25 correlated with significantly lower survival (p<0.035). These results show that the loss of Rab25 promotes the initiation of intestinal polyposis inmice and reductions in Rab25 correlate with poor prognosis in human colorectal cancer. These findings indicate that aberrations in vesicle trafficking may promote intestinal neoplasia.

Aminosalicylates and colorectal cancer in IBD: a not-so bitter pill to swallow.

Inflammatory bowel disease (IBD) is associated with an increased risk of developing intestinal cancer at sites of chronic inflammation. Aminosalicylates, including both sulfasalazine and mesalamine, are the most commonly prescribed anti-inflammatory agents prescribed in IBD. On balance, the body of literature to date suggests that aminosalicylates confer some protection against the development of colonic neoplasia in patients with IBD and in a variety of models, including in the noninflamed gut. This latter observation implies that aminosalicylates may be of chemopreventive value in normal as well as IBD individuals. The current review examines and gives an overview of the evidence from a variety of sources, including epidemiological, in vivo and in vitro studies that have investigated the potential anticancer effects of aminosalicylates.

Development of colonic neoplasia in p53 deficient mice with experimental colitis induced by dextran sulfate sodium

Development of colonic neoplasia in p53 deficient mice with experimental colitis induced by dextran sulfate sodium

This month in J Lab Clin Med: Issue highlights for September 2000

This month in J Lab Clin Med: Issue highlights for September 2000

Site-dependent production of transforming growth factor β1 in colonic mucosa: Its possible role in tumorigenesis of the colon

Transforming growth factor (TGF) β1 has an antitumorigenic role in the gastrointestinal tract and may be associated with the development of colon neoplasia. In the present study we investigated whether TGF-β1 production in mucosa is lower in the distal colon, which is where clinical evidence shows that the incidence of colon neoplasia is higher, and whether TGF-β1 levels were lower in the mucosa of patients with colon adenoma. Production of colon mucosa TGF-β1 was investigated by means of a 24-hour organ culture with biopsy specimens taken from different segments of the colon of 58 normal subjects by using an enzyme immunoassay. TGF-β1 production in colon mucosa from locations near the site of sporadic adenoma was also investigated in 46 patients. TGF-β1 production gradually increased from the rectum to the ascending colon in a statistically significant manner in both normal (r = 0.77, P <.0001) and adenoma-bearing (r = 0.8, P <.0001) mucosa. When TGF-β1 production was compared between normal and adenoma-bearing mucosa, levels were lower in the latter, although statistically significant results were seen only in the transverse colon (P <.05). TGF-β1 production has clear site dependency, being lowest in the rectum and highest in the ascending colon. Furthermore, low levels of TGF-β1 are associated with the development of adenoma. Our results suggest the possibility that this site dependency is associated with the higher epidemiologic incidence of colon neoplasia in the distal colon. (J Lab Clin Med 2000;136:201-8)

Microsatellite instability in colorectal adenomas

BACKGROUND & AIMS: Microsatellite instability in apparently sporadic, predominantly right-sided colon cancers seems to be the result of an acquired, rather than germline, genetic change that impairs mismatch repair. The timing of this change with respect to the adenomacarcinoma sequence has not been determined. The aim of this study was to evaluate colonic adenomatous polyps for microsatellite instability to determine whether instability reflects an early genetic change in colonic neoplasia. METHODS: Ninety-three sporadic colonic adenomas (44 right- sided and 49 left-sided) from 48 individuals were evaluated for microsatellite instability with a set of 10 polymerase chain reaction primer sets. RESULTS: Eighty percent of adenomatous polyps showed no instability. Ninety-eight percent showed instability with <30% of primer sets. Aside from one right-sided adenoma with 78% instability, there was no level of instability with a higher proportion of right- sided than left-sided adenomas. CONCLUSIONS: Colonic adenomas show far less microsatellite instability than carcinomas, and the marked right- sided predominance of instability observed in colon cancers was not observed. Instability is usually not an early event in the development of colonic neoplasia. A distinct pathway to sporadic colorectal cancer initiated by mismatch repair deficiency, although not excluded, is not suggested by these data. (Gastroenterology 1997 May;112(5):1515-9)

L-CAM expression in normal, premalignant, and malignant colon mucosa.

L-CAM is a cell adhesion molecule which is expressed at the intercellular borders of most epithelial cells. L-CAM has been demonstrated to act as an invasion suppressor in carcinoma cell lines. In order to determine whether or not L-CAM expression might distinguish between invasive and non-invasive or metastatic and non-metastatic colon neoplasms, we studied L-CAM expression in normal colon mucosa, colon adenomas with various degrees of dysplasia, and colon carcinomas by immunohistochemistry, using the 6F9 monoclonal anti-L-CAM antibody. Normal mucosa showed evenly distributed distinct L-CAM immunoreactivity along intercellular borders. In adenomas and carcinomas, a similar though weaker expression was observed. This pattern showed a tendency to decrease in parallel with decreasing differentiation. However, no correlation was found with Dukes stage or area within the tumour. In some carcinomas, L-CAM was expressed at the luminal surface of the cells. In others, L-CAM expression was not found. These results suggest that L-CAM expression is disregulated or lost as an early event in the development of colon neoplasia and indicate that L-CAM expression does not correlate with invasive or metastatic potential.

The identification of individuals at high risk for large bowel cancer: an overview.

Attempts to identify individuals with increased susceptibility to colon cancer before clinical manifestations of disease, have recently been made. Early stages of abnormal growth of colonic epithelial cells, and related factors that may contribute to the development of colonic neoplasia have been shown. Based on the identification of early findings, programs to prevent the evolution of malignancy in individuals at increased risk are under consideration at the present time.