Incidence Of Colon Tumors Research Articles

Incidence of right-sided colonic tumors (non-appendiceal) in patient's ≥40 years of age presenting with features of acute appendicitis

IntroductionNon-appendiceal tumors can mimic and present with clinical features of acute appendicitis in patients of age 40 years or above. The aim of this prospective study is to investigate the incidence of right-sided (non-appendiceal) colonic tumors in patients presenting with clinical features of acute appendicitis. MethodsA prospective data analysis of 1662 patients using appendectomy database was performed from 2005 to 2011. Patients above age 40 years or older were included. Patients were compared for demographic data, clinical presentation, radiological findings, operative technique & findings, histo-pathological findings and postoperative complications. The primary outcome was incidence of right-sided colonic (non-appendiceal) tumors presenting with features of acute appendicitis. Secondary outcomes measured were, role of diagnostic radiology, negative appendectomy rate, length of stay and changing trends in operative techniques. ResultsFrom 1662 patients initially reviewed, only 179 patients (10.77%) age 40 years or above mean (56 ± 11.75), median 54 (40–89), with clinical features of acute appendicitis were included in the final analysis. F:M ratio was (1:1.06). CT scan showed in only 1 patient (1.25%, OR = 0.806, p = 0.695), suspicion of cecal tumor and underwent right hemicolectomy. Histological examination of specimen showed, 2 patients (1.11%, OR = 1.10, p = 0.47) had primary appendiceal tumors, in which one patient was histologically reported as appendiceal mucocele (mucinous cystadenoma with low-grade dysplasia), while the other one had appendeceal carcinoid (Goblet cell carcinoid). In the other tumor group one patient had metastatic involvement of appendix from ovarian tumor. The time to appendectomy in radiological group was delayed by (9.2 ± 3.7 h). 131 (73.1%) had laparoscopic while 48 (26.81%) underwent open appendectomy. The negative appendectomy rate was (1.12%) and 30 days complication rate was (11.73%, p = 0.27). Mean length of stay was 3.54 ± 2.1 days. ConclusionRight-sided colonic (cecal) tumors rarely present with features of acute appendicitis. Only those patients with atypical presentation and findings should have pre-operative radiological evaluation.

A chemoprotective fish oil/pectin diet enhances apoptosis via Bcl-2 promoter methylation in rat azoxymethane-induced carcinomas

We have demonstrated that diets containing fish oil and pectin (FO/P) reduce colon tumor incidence relative to control (corn oil and cellulose [CO/C]) in part by inducing apoptosis of DNA-damaged colon cells. Relative to FO/P, CO/C promotes colonocyte expression of the antiapoptotic modulator, Bcl-2, and Bcl-2 promoter methylation is altered in colon cancer. To determine if FO/P, compared with CO/C, limits Bcl-2 expression by enhancing promoter methylation in colon tumors, we examined Bcl-2 promoter methylation, mRNA levels, colonocyte apoptosis and colon tumor incidence in azoxymethane (AOM)-injected rats. Rats were provided diets containing FO/P or CO/C, and were terminated 16 and 34 weeks after AOM injection. DNA isolated from paraformaldehyde-fixed colon tumors and uninvolved tissue was bisulfite modified and amplified by quantitative reverese transcriptase-polymerase chain reaction to assess DNA methylation in Bcl-2 cytosine-guanosine islands. FO/P increased Bcl-2 promoter methylation (P = 0.009) in tumor tissues and colonocyte apoptosis (P = 0.020) relative to CO/C. An inverse correlation between Bcl-2 DNA methylation and Bcl-2 mRNA levels was observed in the tumors. We conclude that dietary FO/P promotes apoptosis in part by enhancing Bcl-2 promoter methylation. These Bcl-2 promoter methylation responses, measured in vivo, contribute to our understanding of the mechanisms involved in chemoprevention of colon cancer by diets containing FO/P.

Cytosolic Malic Enzyme 1 (ME1) Mediates High Fat Diet-Induced Adiposity, Endocrine Profile, and Gastrointestinal Tract Proliferation-Associated Biomarkers in Male Mice

BackgroundObesity and associated hormonal disturbances are risk factors for colon cancer. Cytosolic Malic Enzyme (ME1) generates NADPH used for lipogenesis in gastrointestinal (GI), liver and adipose tissues. We have reported that inclusion of soy protein isolate (SPI) in the diet lowered body fat content and colon tumor incidence of rats fed AIN-93G diet, while others have demonstrated SPI inhibition of rat hepatic ME1 expression. The present study examined the individual and combined effects of dietary SPI and absence of ME1 on: 1) serum concentrations of hormones implicated in colon cancer development, 2) expression of lipogenic and proliferation-associated genes in the mouse colon and small intestine, and 3) liver and adipose expression of lipogenic and adipocytokine genes that may contribute to colon cancer predisposition.MethodsWeanling wild type (WT) and ME1 null (MOD-1) male mice were fed high-fat (HF), iso-caloric diets containing either casein (CAS) or SPI as sole protein source for 5 wks. Somatic growth, serum hormone and glucose levels, liver and adipose tissue weights, GI tissue parameters, and gene expression were evaluated.ResultsThe MOD-1 genotype and SPI-HF diet resulted in decreases in: body and retroperitoneal fat weights, serum insulin, serum leptin, leptin/adiponectin ratio, adipocyte size, colon mTOR and cyclin D1 mRNA abundance, and jejunum FASN mRNA abundance, when compared to WT mice fed CAS-HF. Regardless of diet, MOD-1 mice had reductions in liver weight, liver steatosis, and colon crypt depth, and increases in adipose tissue expression of IRS1 and IRS2, compared to WT mice. SPI-HF diet reduced ME1 gene expression only in retroperitoneal fat.ConclusionsData suggest that the pharmacological targeting of ME1 or the inclusion of soy protein in the diet may provide avenues to reduce obesity and its associated pro-tumorigenic endocrine environment and improve insulin sensitivity, potentially disrupting the obesity-colon cancer connection.

An apoptosis-independent role of SMAC in tumor suppression.

Reduced expression of the pro-apoptotic protein SMAC (second mitochondria-derived activator of caspase) has been reported to correlate with cancer progression, while its significance and underlying mechanisms are poorly understood. In this study, we investigated the role of SMAC in intestinal tumorigenesis using both human samples and animal models. Decreased SMAC expression was found to correlate with increased cIAP2 expression and higher grades of human colon cancer. In mice, SMAC deficiency significantly increased the incidence and size of colon tumors induced by azoxymethane (AOM)/dextran sulfate sodium salt (DSS), and highly enriched β-catenin hot spot mutations. SMAC deficiency also significantly increased the incidence of spontaneous intestinal polyps in APC(Min/+) mice. Loss of SMAC in mice led to elevated levels of cIAP1 and cIAP2, increased proliferation and activation of the NF-κB p65 subunit in normal and tumor tissues. Unexpectedly, SMAC deficiency had little effect on the incidence of precursor lesions, or apoptosis induced by AOM or DSS, or in established tumors in mice. Furthermore, SMAC knockout enhanced TNFα-mediated NF-κB activation via cIAP2 in HCT 116 colon cancer cells. These results demonstrate an essential and apoptosis-independent function of SMAC in tumor suppression and provide new insights into the biology and targeting of colon cancer.

Abstract LB-177: A supercritical turmeric extract prevents small intestinal and colonic tumors in the APCMin/+ mice by suppressing proliferation and cancer stem cell markers

Abstract CRC is one of the most commonly diagnosed cancers in the United States. Curcumin, a principle compound in turmeric, has been extensively investigated and proven to be antiinflammatory and anticarcinogenic against numerous cancers including CRC. Turmeric is consumed as a dietary ingredient by large populations and turmeric extracts as a dietary supplement by healthy as well as high-risk individuals with various chronic diseases. Turmeric, however, contains over 300 different compounds including essential oils; curcuminoids, turmerones, etc. Most turmeric extracts commonly used as dietary supplements contains <6% curcuminoids; however, to date no studies have been undertaken to determine whether these turmeric extracts are effective or not in comparison to curcumin in preventing colonic tumors. In this study, we tested a supercritical extract of turmeric (TurmericForce™) in comparison to an equal amount of curcumin against the APC-min/+ SI and colon polyposis model. Six-week-old male APC-Min/+ mice (n = 15 per group) were fed with control AIN-76A diet or diets containing 2,000 ppm turmeric extract or 2,000 ppm or 120 ppm curcumin for 14 weeks; intestinal tumors were then evaluated for tumor incidence and multiplicity. Mice fed with either 2,000 ppm turmeric extract or curcumin exhibited a significantly suppressed SI polyp multiplicity by 26.3 ±8.3 (Mean±SD; 45.5%, p<0.0001) and 32.5 ±7.8 (32.5%, P<0.0001), respectively. Importantly, the 2,000 ppm turmeric extract showed significantly (p<0.026) better inhibitory effect compared to 2,000 ppm curcumin in SI polyp suppression. Colon tumor incidences were 77%, 54%, and 50% for mice fed control, turmeric extract and curcumin, respectively. Furthermore, colonic tumor multiplicities were 1.46 ± 1.1 (control); 0.57± 0.6 (turmeric extract, 61%inhibition, p<0.01) and 0.61±0.65 (2,000 ppm curcumin, 56% inhibition, p<0.015). In contrast, 120 ppm curcumin (equal to curcumin content in turmeric extract) produced limited SI tumor inhibitory effects (14% inhibition) in APC-Min/+ mice. Both turmeric extract and curcumin showed a significant reduction is PCNA and β-catenin expression levels and an increase in p21 and TUNEL positive cells. Also, Real time PCR and IHC analysis showed a significant reduction in cancer stem (CD133 and ALDH1) marker positive cells by the turmeric extract and curcumin. These results suggest that the supercritical turmeric extract had equal or better chemopreventive properties than curcumin alone in suppressing intestinal tumorigenesis. {Supported by Kerley-Cade Endowment} 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 LB-177. doi:1538-7445.AM2012-LB-177

Abstract LB-170: A role of sphingosine kinase 1 in peritoneal macrophages on the early stages of colon carcinogenesis

Abstract Our previous studies indicate that the Sphingosine kinase 1 (SphK1)/Sphingosine 1-phosphate (S1P) pathway mediates colon carcinogenesis at least by regulating COX-2 expression and prostaglandin E2 (PGE2) production. However, the mechanisms by which this pathway regulates colon carcinogenesis are still unclear. First, we show that SphK1 deficient mice significantly attenuated azoxymethane (AOM)-induced colon carcinogenesis as measured by colon tumor incidence, multiplicity, and volume. We found that AOM activates peritoneal macrophages to induce SphK1, COX-2, and TNF-α expression in WT mice. Interestingly, SphK1 KO mice revealed significant reduction of COX-2 and TNF-α expression from AOM-activated peritoneal macrophages, suggesting that SphK1 regulates COX-2 and TNF-α expression in peritoneal macrophages. Finally, we found that inoculation of WT peritoneal macrophages “rescued” the carcinogenic effect of AOM in Sphk1 KO mice as measured by aberrant crypt foci (ACF) formation, preneoplastic lesions of colon cancer, indicating that SphK1 expression in peritoneal macrophages is required in the early stages of colon carcinogenesis when induced by AOM. These results suggest that SphK1 expression plays a pivotal role in the early stages of colon carcinogenesis through regulating COX-2 and TNF-α expression from activated peritoneal macrophages. 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 LB-170. doi:1538-7445.AM2012-LB-170

Abstract 1631: Protection of colon carcinogenesis by estrogen receptor-beta may involve regulation of angiogenesis and invasion specific signaling molecules

Abstract Estrogen receptor-beta (ERα) has been suggested to exert anti-tumorigenic effects in the colon. However, its mechanism of action in colon cancer remains unclear. Previously, we demonstrated that azoxymethane (AOM) treated ERα knockout (≥ERKO) mice showed a significantly higher incidence of colonic precancerous lesions compared to AOM-treated WT mice. These results were associated with a decrease in apoptosis and loss of crypt organization in the colonic epithelium of αERKO mice. In the present study, we investigated whether ERα deficiency would also correlate with a higher incidence of colonic tumors. For this, αERKO and WT mice were injected subcutaneously with AOM (10mg/kg) once a week, for six weeks. Forty weeks after the beginning of the study, mice were sacrificed and colonic sections were collected for histopathology, RNA, and protein expression analysis. Evaluation of hematoxylin and eosin sections from each group showed that αERKO mice developed higher number of colonic adenomas (1.40 ± 0.40) than WT mice (0.33 ± 0.21) (p < 0.05). Furthermore, Mouse Cancer PathwayFinder Superarray revealed a greater than two-fold increase of angiogenesis and invasion specific signaling molecules in ERα-deficient tumors compared to WT ones. These findings highlight the importance of ERα against colon carcinogenesis progression. 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 1631. doi:1538-7445.AM2012-1631

Increased carcinogen‐induced colon cancer in ERβKO compared to Wild Type mice

Colon cancer risk is influenced by estrogen exposure, although the mechanism through which this occurs is not defined. Conversion of estrogen to estrone appears to be protective in colon and is lost in colon tumors. We hypothesized that dietary phytoestrogens or estrone would reduce colon tumorigenesis via an estrogen receptor beta (ERβ) dependent mechanism. Ovariectomized ERβKO or wild type female mice were fed diets containing casein, soy protein lacking isoflavones (Soy‐IF), soy protein+genistein (Soy+Gen), soy protein+NovaSoy (Soy+NS) or soy protein+estrone (Soy+E1) from weaning. Colon tumors were induced with 6 weekly injections of azoxymethane (AOM). At termination (32–38 weeks after AOM), colon tumor incidence was lower in WT (32%) compared to ERβKO (48%) mice. ERβKO and WT mice fed Soy+Gen had lower tumor incidence than mice fed all other diets. Despite no overall differences in total body weight, mice fed estrone had higher body fat weight than the other groups. No differences in colonic TNFα, IL‐10 and other cytokines due to diet or genotype were found, except IL‐1β was significantly higher in WT mice fed soy‐IF or Soy+NS compared to other diets. This study demonstrates a protective role for ERβ and suggests a protective effect of soy phytoestrogens in colon cancer. The mechanism does not appear to be due to modulation of the colonic immune system.

Hypoxia‐inducible factor‐2α regulates intestinal inflammation and colon cancer

A combination of a disturbed function of the intestinal epithelial barrier and a dysregulation of the mucosal immune system are critical in the pathogenesis of Inflammatory bowel disease (IBD). Moreover, IBD is a major risk factor for colorectal cancer. Significant increases in focal hypoxia and its associated transcription factors have been observed during the pathogenesis of colitis and colon cancer. Regulation of hypoxia‐mediated genes is dependent on the nuclear transcription factor, hypoxia‐inducible factor (HIF)1α and HIF2α. HIF1α has been shown to be critical in maintaining the integrity of intestinal epithelial barrier during the pathogenesis of colitis. However, the role of HIF2α in inflammatory lesions in the intestine and colorectal cancer remains less clear. Here we developed novel mouse models with intestine‐specific gain‐of‐function and loss‐of‐function of HIF2α to investigate the role of HIF2α in experimental colitis and colon tumorigenesis. Activation of HIF2α potentiated inflammation, whereas deletion of HIF2α attenuated inflammation in an acute model of colitis. Moreover, HIF2α was critical in the apoptotic response following tissue injury. Since, chronic inflammation is major risk factor for colon cancer and HIF2α was shown to be critical in intestinal inflammation and apoptosis, studies assessing the role of HIF2α in colon carcinogenesis were also performed. The data demonstrated that activation of HIF2α increases colon tumor multiplicity, incidence, and progression. Together, our data suggest an important role of HIF2α as a molecular link between intestinal inflammation and cancer.

Comparison of Chemopreventive Properties of Zanthoxylum armatum and Hibiscus sabdariffa on colorectal adenocarcinoma cell (COLO 201) through apoptosis process

Comparison of Chemopreventive Properties of Zanthoxylum armatum and Hibiscus sabdariffa on colorectal adenocarcinoma cell (COLO 201) through apoptosis processVarious concentrations of Zanthoxylum armatum and Hibiscus sabdariffa are used in this experiment to determine the optimum dose for cell cytotoxicity effects on COLO 201 cells. Antioxidant index of both phytochemicals were determine by using antioxidant assay kit. Annexin‐v, caspases 3/7 and in situ cell proliferation methods were used to determine the apoptosis induction through the flow cytometry. Results of this experiment indicated that lower concentration (5 mM/g) of both phytochemicals in combination induced significant amount of cell deaths in two stages of cell cycle (apoptosis 53.79 and early apoptosis 18.11%) compared to other treatment groups and control. Findings of this experiment support that the traditional use of these two herbs in the treatment of various chronic diseases is justified. These findings also suggest that the synergistic effect of these phytochemicals may reduce the incidence of colon tumors and can develop as a chemopreventive agent.

Effect of angiostatin on 1,2-dimethylhydrazine-induced colon cancer in mice

Antiangiogenic therapy is supposed to be an attractive approach for antitumor treatment. Human plasminogen-derived angiostatin K1-3 is one of the most potent antiangiogenic agents known currently. However, it is unclear whether angiostatin has got protective effects on colon cancer. So we investigated the protective effects of angiostatin on 1,2-dimethylhydrazine (DMH)-induced colon cancer in mice. Thirty Balb/C male mice, weighing 25-30g and 8 weeks of age, were used. Twenty of the mice were treated with DMH subcutaneously (20mg/kg) once a week for 12 weeks. Six mice died during the DMH injection and surviving mice were divided into two groups (7 mice in DMH and 7 mice in DMH+angiostatin groups). In the angiostatin group, 6 weeks after the last DMH injection the animals were first treated with angiostatin (20μg/mouse) intraperitoneally and then subcutaneously every 48h (5μg/mouse) throughout a period of 12 weeks. The animals were killed after 30 weeks for histopathological examination. When we look at the distribution of lesions in the colon, they mainly occurred in the distal colon. The incidence of mean colonic lesions in a tumor-bearing mouse was 9.85±4.91 in those treated with DMH and 8.71±3.49 in those treated with angiostatin. The incidence of colon tumors was not significantly affected by low dose of angiostatin, and we noticed that the number of lesions decreased by 12% in DMH+angiostatin group compared to the number of the lesions in DMH group, but this decrease was not statistically significant (p>0.05). The administration period of angiostatin corresponds to the precancerous period and the reduction in the number of lesions could be important for the protective function of angiostatin in DMH+angiostain group. We assume that therapeutic effects of angiostatin are related to its doses, route of administration, frequency and administration period. In addition, we believe that combination of high doses of angiostatin with radiation, gene therapy or chemotherapy might be successful in proper tumor model.

Trends in Colorectal Cancer Incidence Rates in the United States by Tumor Location and Stage, 1992–2008

Results from case-control studies outside the United States have been conflicted about the efficacy of colonoscopy for reducing cancer risk in the right colon. To contribute to this discourse from an alternative perspective, we analyzed high-quality surveillance data to report on recent trends in population-based colorectal cancer incidence rates by tumor location in the United States. Data from cancer registries in the Surveillance, Epidemiology, and End Results Program were analyzed to examine colorectal cancer incidence trends from 1992 through 2008 among individuals aged ≥ 50 years (n = 267,072). Joinpoint regression analysis was used to quantify annual percent change in age-standardized rates by tumor location and disease stage. Incidence rates for right-sided colon tumors decreased annually by 2.6% (95% CI: 2.0-3.2) since 1999 in men and 2.3% (CI: 1.6-3.0) since 2000 in women, after remaining stable during the previous seven/eight years. Incidence rates for left-sided tumors were generally decreasing from 1992 to 2008 in both sexes. Beginning in 1999/2000, substantial, almost identical annual declines occurred for late-stage disease in both the right and left colon: 3.9% (CI: 3.1-4.8) and 4.2% (CI: 3.5-4.9), respectively, in men; and 3.3% (CI: 2.5-4.1) and 3.3% (CI: 2.8-3.8) in women. Large declines in the incidence of right-sided colon tumors among individuals 50 years and older began around 2000. Increased colonoscopy utilization during the past decade may have contributed to a reduction in risk for cancers in both the right and left colorectum in the United States.

Cyclooxygenase as a Target for Colorectal Cancer Chemoprevention

Colorectal cancer (CRC) is one of the most common neoplasia in Western countries and the second leading cause of cancer-related death. The vast majority of cases belong to sporadic forms, whereas a small but relevant proportion of them corresponds to inherited disorders, i.e. familial adenomatous polyposis and Lynch syndrome. These individuals with germline mutations in cancer-promoting genes, along with those who had already developed a colorectal neoplasm, either adenoma or carcinoma, stand to benefit from chemopreventive interventions. A large body of evidence indicates that the use of aspirin and other non-steroidal anti-inflammatory drugs (NSAID) can reduce the risk of CRC. Experimental studies have demonstrated that these drugs decrease the incidence of carcinogen-induced colon tumors in rodents, and several epidemiological investigations and therapeutic trials have also shown a 40-50% reduction in the risk of colorectal adenoma and cancer in individuals taking NSAIDs. Moreover, patients with familial adenomatous polyposis taking sulindac or celecoxib experience a reduction in adenoma size and number. The chemopreventive effects of NSAID are largely related to inhibition of cyclooxygenase-2 (COX-2), the inducible isoform of cyclooxygenase that catalyzes the conversion of arachidonic acid to prostaglandins. COX-2 overexpression is a frequent, but not universal event in colorectal neoplasms. Indeed, approximately 50% of adenomas and 80% of CRC express high levels of COX-2 mRNA and protein in neoplastic tissue. In this article, we will review the role of cyclooxygenase as a target for CRC chemoprevention, with special attention to the use of selective and non-selective COX-2 inhibitors in both individuals genetically predisposed and those who have already developed a colorectal neoplasm.

Combination of atorvastatin with sulindac or naproxen profoundly inhibits colonic adenocarcinomas by suppressing the p65/β-catenin/cyclin D1 signaling pathway in rats.

Evidence supports the protective role of nonsteroidal anti-inflammatory drugs (NSAID) and statins against colon cancer. Experiments were designed to evaluate the efficacies atorvastatin and NSAIDs administered individually and in combination against colon tumor formation. F344 rats were fed AIN-76A diet, and colon tumors were induced with azoxymethane. One week after the second azoxymethane treatment, groups of rats were fed diets containing atorvastatin (200 ppm), sulindac (100 ppm), naproxen (150 ppm), or their combinations with low-dose atorvastatin (100 ppm) for 45 weeks. Administration of atorvastatin at 200 ppm significantly suppressed both adenocarcinoma incidence (52% reduction, P = 0.005) and multiplicity (58% reduction, P = 0.008). Most importantly, colon tumor multiplicities were profoundly decreased (80%-85% reduction, P < 0.0001) when given low-dose atorvastatin with either sulindac or naproxen. Also, a significant inhibition of colon tumor incidence was observed when given a low-dose atorvastatin with either sulindac (P = 0.001) or naproxen (P = 0.0005). Proliferation markers, proliferating cell nuclear antigen, cyclin D1, and β-catenin in tumors of rats exposed to sulindac, naproxen, atorvastatin, and/or combinations showed a significant suppression. Importantly, colon adenocarcinomas from atorvastatin and NSAIDs fed animals showed reduced key inflammatory markers, inducible nitric oxide synthase and COX-2, phospho-p65, as well as inflammatory cytokines, TNF-α, interleukin (IL)-1β, and IL-4. Overall, this is the first report on the combination treatment using low-dose atorvastatin with either low-dose sulindac or naproxen, which greatly suppress the colon adenocarcinoma incidence and multiplicity. Our results suggest that low-dose atorvastatin with sulindac or naproxen might potentially be useful combinations for colon cancer prevention in humans.

Intestinal carcinogenesis of two food processing contaminants, 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine and 5‐hydroxymethylfurfural, in transgenic FVB min mice expressing human sulfotransferases

Humans express sulfotransferases (SULTs) of the SULT1A subfamily in many tissues, whilst the single SULT1A gene present in rodents is mainly expressed in liver. The food processing contaminants, 5-hydroxymethylfurfural (HMF) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), are bioactivated by human SULT1A1 and SULT1A2. FVB multiple intestinal neoplasia (Min) mice, which spontaneously develop tumors and flat aberrant crypt foci (ACF) in intestine, were crossed with transgenic FVB mice expressing human SULT1A1 and 1A2 (hSULT) in several tissues, giving rise to wild-type and Min mice with and without hSULT. One-week-old Min mice with or without hSULT were given HMF (375 or 750 mg/kg bw) or saline by gavage three times a week for 11 wk. In another experiment, the F1 generation received subcutaneous injections of 50 mg/kg bw PhIP or saline 1 wk before birth, and 1, 2, and 3 wk after birth. HMF did not affect the formation of tumors, but may have induced some flat ACF (incidence 15-20%) in Min mice with and without hSULT. No control mouse developed any flat ACF. With the limitation that these putative effects were weak, they were unaffected by hSULT expression. The carcinogenic effect of PhIP increased in the presence of hSULT, with a significant increase in both incidence (31-80%) and number of colonic tumors (0.4-1.3 per animal). Thus, intestinal expression of human SULT1A1 and 1A2 might increase the susceptibility to compounds bioactivated via this pathway implying that humans might be more susceptible than conventional rodent models.

Abstract B46: Dietary acrylamide differentially modulates azoxymethane-induced F344 rat colon tumor formation and ectopic growth of human colon tumor cells in nude (nu/nu) mice

Abstract Acrylamide, a known rodent and a possible human carcinogen is ubiquitously formed in foods at high temperature. We earlier reported that dietary acrylamide at doses known to cause rodent tumors, did not increase the formation of azoxymethane (AOM)-induced colon aberrant crypt foci (ACF), putative precancerous lesions. On the contrary, we observed a significant decrease in ACF in rats receiving acrylamide at 10 and 50 mg/kg diet and a trend to increase ACF at the lowest dose (5mg acrylamide/kg diet) tested. In this study using two rodent models, we assessed if dietary acrylamide, at levels reflecting those in popular human foods, modulated colon tumor formation and progression. In Experiment-1, 4 groups of weanling male F344 rats received AIN-93G diets with acrylamide at 0.5, 1.0 or 2.0 mg/kg diet or without (0 mg/kg diet, control). After two weeks, rats in each diet group received either two weekly s.c. injections of AOM or saline. All rats were on the experimental diets ad libitum for 20 weeks post AOM/saline injections after which they were killed and their colons assessed for tumors. In Experiment-2, athymic nude (nu/nu) mice were s.c. injected with HT-29 human colon adenocarcinoma cells and tumors were allowed to grow for 3 weeks after which they received one of the 4 experimental diets; tumor growth was monitored bi-weekly and mice were killed 4 weeks after. None of the saline-injected rats had tumors in their colon. 23 rats that received acrylamide had blood in their stool at 19 weeks post-AOM injections, and hence the study was stopped in a timely manner at 20 weeks post-AOM injections. The colon tumor incidence was 54.2% in the control group and 66.67% in the highest acrylamide-treated group (2 mg/kg diet). Tumor multiplicity was similar across all diet groups. However, tumor size and burden were higher in the group that received 2 mg/kg acrylamide by comparison to the control. These results suggest acrylamide by itself is not a “carcinogen” at upper exposure levels commonly seen in popular foods, but acts as a “co-carcinogen” at the highest tested dose by exacerbating the risk of developing colon tumors by a known colon-specific carcinogen AOM. The nude mice study indicated no differences in ectopic human colon tumor growth between acrylamide-treated and control mice suggesting that acrylamide at the levels tested does not aid in the progression of established human tumors in this experimental model. Our data provides characterization of acrylamide as a possible colon cancer promoter in association with a known and possibly other environmental tumor initiators/promoters. This additional information will be useful in defining the health risks of acrylamide when exposed through the diet, and will assist regulators in developing a better understanding of the relevance to humans. Citation Information: Cancer Prev Res 2011;4(10 Suppl):B46.

Immunomodulatory action of dietary fish oil and targeted deletion of intestinal epithelial cell PPARδ in inflammation-induced colon carcinogenesis

The ligand-activated transcription factor peroxisome proliferator-activated receptor (PPAR)-δ is highly expressed in colonic epithelial cells; however, the role of PPARδ ligands, such as fatty acids, in mucosal inflammation and malignant transformation has not been clarified. Recent evidence suggests that the anti-inflammatory/chemoprotective properties of fish oil (FO)-derived n-3 polyunsaturated fatty acids (PUFAs) may be partly mediated by PPARδ. Therefore, we assessed the role of PPARδ in modulating the effects of dietary n-3 PUFAs by targeted deletion of intestinal epithelial cell PPARδ (PPARδ(ΔIEpC)). Subsequently, we documented changes in colon tumorigenesis and the inflammatory microenvironment, i.e., local [mesenteric lymph node (MLN)] and systemic (spleen) T cell activation. Animals were fed chemopromotive [corn oil (CO)] or chemoprotective (FO) diets during the induction of chronic inflammation/carcinogenesis. Tumor incidence was similar in control and PPARδ(ΔIEpC) mice. FO reduced mucosal injury, tumor incidence, colonic STAT3 activation, and inflammatory cytokine gene expression, independent of PPARδ genotype. CD8(+) T cell recruitment into MLNs was suppressed in PPARδ(ΔIEpC) mice. Similarly, FO reduced CD8(+) T cell numbers in the MLN. Dietary FO independently modulated MLN CD4(+) T cell activation status by decreasing CD44 expression. CD11a expression by MLN CD4(+) T cells was downregulated in PPARδ(ΔIEpC) mice. Lastly, splenic CD62L expression was downregulated in PPARδ(ΔIEpC) CD4(+) and CD8(+) T cells. These data demonstrate that expression of intestinal epithelial cell PPARδ does not influence azoxymethane/dextran sodium sulfate-induced colon tumor incidence. Moreover, we provide new evidence that dietary n-3 PUFAs attenuate intestinal inflammation in an intestinal epithelial cell PPARδ-independent manner.

Green Tea, Phytic Acid, and Inositol in Combination Reduced the Incidence of Azoxymethane-Induced Colon Tumors in Fisher 344 Male Rats

Experimental as well as epidemiologic studies in human populations provide evidence that consumption of phytochemicals reduces the incidence of degenerative diseases. Green tea (GT) catechins are known for their antioxidative potential. Phytic acid (PA) also acts as a natural antioxidant and may have numerous health benefits. This experiment was designed to investigate the inhibitory effects of combinations of 1% and 2% GT, PA, and inositol (I) in reducing the incidence of azoxymethane-induced colon tumors in Fisher 344 male rats. After an acclimatization period of 1 week, nine groups of rats (15 rats per group) were initially assigned to consume AIN 93 G diet and later AIN 93 M diet after 20 weeks of age. Treatments were given in drinking water. All rats received azoxymethane injections (16 mg/kg of body weight) subcutaneously at 7 and 8 weeks of age. Rats were killed at 45 weeks of age by CO(2) euthanasia. Tumor incidence (93.76%) and the number of tumors per tumor-bearing rat ratio (2.25) were significantly (P<.05) higher in the control group compared with treatment groups. Glutathione S-transferase activity was significantly (P<.05) higher in rats fed combinations of 2% GT+PA+I and GT+PA (33.25 ± 1.23 and 29.83 ± 1.10 μmol/mL, respectively) compared with other groups. These findings suggest that the synergistic effect of the 2% level of GT, PA, and I may reduce the incidence of colon tumors and therefore have potential as a chemopreventive agent.

Heparanase powers a chronic inflammatory circuit that promotes colitis-associated tumorigenesis in mice

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that is closely associated with colon cancer. Expression of the enzyme heparanase is clearly linked to colon carcinoma progression, but its role in UC is unknown. Here we demonstrate for what we believe to be the first time the importance of heparanase in sustaining the immune-epithelial crosstalk underlying colitis-associated tumorigenesis. Using histological specimens from UC patients and a mouse model of dextran sodium sulfate-induced colitis, we found that heparanase was constantly overexpressed and activated throughout the disease. We demonstrate, using heparanase-overexpressing transgenic mice, that heparanase overexpression markedly increased the incidence and severity of colitis-associated colonic tumors. We found that highly coordinated interactions between the epithelial compartment (contributing heparanase) and mucosal macrophages preserved chronic inflammatory conditions and created a tumor-promoting microenvironment characterized by enhanced NF-κB signaling and induction of STAT3. Our results indicate that heparanase generates a vicious cycle that powers colitis and the associated tumorigenesis: heparanase, acting synergistically with the intestinal flora, stimulates macrophage activation, while macrophages induce production (via TNF-α-dependent mechanisms) and activation (via secretion of cathepsin L) of heparanase contributed by the colon epithelium. Thus, disruption of the heparanase-driven chronic inflammatory circuit is highly relevant to the design of therapeutic interventions in colitis and the associated cancer.

A chemoprotective fish oil/pectin diet regulates the expression of the bcl‐2 oncogene by altering CpG island methylator phenotype (CIMP) in colon cancer

We have demonstrated that diets containing fish oil and pectin (FO/P) reduce colon tumor incidence relative to those containing corn oil and cellulose (CO/C) in part by inducing apoptosis. CO/C, as compared to FO/P, promotes colonocyte expression of the anti‐apoptotic protein, bcl‐2, and bcl‐2 promoter methylation is altered in colon cancer. To determine if CO/C promotes bcl‐2 expression by reducing promoter methylation in colon cancer, we examined bcl‐2 promoter methylation and mRNA levels, and colonocyte apoptosis (TUNEL assay). Rats were provided diets containing FO/P or CO/C, and were terminated 36 wk after azoxymethane injection (2×, 15 mg/kg BW, sc). DNA isolated from 10 μm sections of PFA‐fixed colon carcinomas was bisulfite modified and amplified by real time qPCR to assess regions of the bcl‐2 CpG islands. Scraped mucosa from the same rats was also used to quantify bcl‐2 mRNA levels. FO/P treatment increased bcl‐2 DNA methylation (p = 0.055) and apoptosis (p = 0.022) as compared to CO/C. Data analysis revealed a negative relationship between bcl‐2 DNA methylation and bcl‐2 mRNA levels. We conclude that dietary FO/P promotes apoptosis by enhancing bcl‐2 promoter methylation relative to a CO/C diet. This study is the first to detect a diet effect on promoter methylation of the bcl‐2 oncogene in the colon. Funded by NSBRI NASA NCC 9‐58 and NIH CA59034.