Methylation study of tumor suppressor genes in human aberrant crypt foci, colorectal carcinomas, and normal colon

BACKGROUND

Aberrant crypt foci (ACF) are the earliest preneoplastic lesions in human colon, identifiable on chromoendoscopic screening. Our objective was to evaluate the %methylation of APC, CDKN2A, MLH1, RASSF1, MGMT, and WIF1 tumor suppressor genes (TSG) in ACF, corresponding colorectal carcinomas (CRC), and normal colonic mucosal controls.

METHODS

In this study, macroscopically normal-appearing mucosal flaps were sampled 5-10 cm away from the tumor mass from 302 fresh colectomy specimens to identify ACF-like lesions. Thirty-five cases with multiple ACFs were selected (n 35) as the main study group, with corresponding sections from CRC (n 35) as disease controls, and mucosal tissue blocks from 20 colectomy specimens (normal controls), operated for non-neoplastic pathologies. Genomic DNA was extracted, and methylation-specific polymerase chain reaction (PCR) was performed on a customized methylation array model. %Methylation data were compared among the groups and with clinicopathological parameters. Selected target mRNA and protein expression studies were performed.

RESULTS

%Methylation of TSGs in ACF was intermediate between normal colon and CRC, although a statistically significant difference was observed only for the WIF1 gene (P < 0.01). Also, there was increased nuclear β-catenin expression and upregulation of CD44-positive cancer-stem cells in ACF and CRCs than in controls. Right-sided ACFs and dysplastic ACFs had a higher %methylation of CDKN2A (P < 0.01), whereas hyperplastic ACFs had a higher %methylation of RASSF1 (P 0.04). The topographic characteristics of ACFs did not correlate with TSG %methylation.

CONCLUSIONS

Early epigenetic methylation of WIF1 gene is one of the mechanisms for ACF development in human colon.

Targeting the Leukotriene Pathway for Colon Cancer Interception

The role of chronic inflammation and arachidonic acid (AA) metabolism in tumor progression has been well characterized for variety of cancers, with compelling data for colon cancer. Several preclinical and clinical studies primarily focused on inhibiting the cyclooxygenase pathways using NSAIDs and aspirin for colon cancer prevention. However, emerging evidence clearly supports the pro-tumorigenic role of 5-lipoxygenase and its downstream leukotriene pathway within AA metabolism. As discussed in the current issue, targeting the leukotriene pathway by cysteinyl leukotriene receptor antagonist (LTRA) montelukast suppressed formation of aberrant crypt foci (ACF) and cell proliferation in colonic epithelium, suggesting the potential of LTRAs for colon cancer prevention. Although this is a short clinical chemoprevention trial to explore the effects of LTRAs against ACF development, it is a significant and timely study opening avenues to further explore the possibilities of using LTRAs in other inflammation-associated precancerous lesions as well. In this spotlight commentary, we highlight the implications of their data and the opportunities for developing LTRAs as potential candidates for colorectal cancer interception. See related article by Higurashi et al., p. 661.

Antitumor and hepatoprotective effect of Cuscuta reflexa Roxb. in a murine model of colon cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Cuscuta reflexa Roxb. (C. reflexa) is a well-known traditional herbal plant, with numerous inherent therapeutic potentials including anticancer, antitumor, antibacterial, analgesic, anthelmintic, laxative and others. Moreover, the anticancer and antitumor potentials of this herb are ongoing with several trails, thus an attempt was made to assess the anticancer and hepatoprotective potentials of traditional C. reflexa herbs.

METHOD

The dried ethanolic extract of C. reflexa was tested for acute oral toxicity in the treated animals subsequently their behavioral, neurological, and autonomic profiles changes were observed. The preliminary anti-cancer effects of extracts against 1, 2- Dimethyl hydrazine (DMH) induced animals were assessed through barium enema X-ray, colonoscopy, and Aberrant crypt foci (ACF) studies. The blood samples of the animals (treated and untreated) were collected and their in-vitro histological parameters were evaluated by the experienced technician.

RESULTS

It was observed that C. reflexa significantly reduced Disease activity indexing (DAI) level and ACF counting, as well as demonstrated similar activity as of the standard drug 5-Fluorouracil (5-FU). Histopathological results revealed that the apoptotic bodies decreased in the DMH-induced group (group II) during cancer progression while in 5-FU treated (group III) and C. reflexa treated (group IV and V) animals the apoptotic bodies were increased. Inversely, the mitotic bodies increased in group II animals and reduced in group III, IV, and V animals. In the colonic section, DMH-induced cancer assay exhibited significant effects on the levels of hemoglobin, Packed cell volume (PCV), Red blood cell (RBC) counts, Mean corpuscular hemoglobin concentration (MCHC), Mean corpuscular volume (MCV), and Mean cell hemoglobin (MCH), and was found to be less in group II animals whereas administration of C. reflexa efficiently recovered back the loss probably by healing the colon damage/depletion of cancer progression. Moreover, compared to the group II animals, the neutrophil count was within the normal range in C. reflexa administered group.

CONCLUSIONS

In the present study, the major hematological parameters significantly increased within DMH treated animals and exhibited extensive damage in the hepatic regions. Moreover, the histopathological findings demonstrated that the C. reflexa extracts potentially reduced the cell proliferation, with no toxicity. The C. reflexa extracts exhibited impending anti-cancer activity as well as protected the hepatic cells and thus could be potentially used in the management of colon or colorectal cancer and hepatic impairments.

The Use of Natural Fiber-Rich Food Product Is Safe and Reduces Aberrant Crypt Foci in a Pre-Clinical Model

BACKGROUND

Colorectal cancer is a highly prevalent disease, requiring effective strategies for prevention and treatment. The present research aimed to formulate a natural fiber-rich food product (NFRFP) and to evaluate its safety, toxicogenetics, and effects on aberrant crypt foci induced by 1,2-dimethyl-hydrazine in a preclinical model.

METHODS

A total of 78 male Wistar rats were distributed in six experimental groups: negative control, positive control (1,2-Dimethylhydrazine-40 mg/Kg), and four groups fed with 10% NFRFP: NFRFP, pre-treatment protocol, simultaneous treatment, and post-treatment protocol.

RESULTS

The NFRFP was shown to be a good source of fibers and did not change biometric, biochemical, hematological, and inflammatory parameters, and did not induce signs of toxicity and genotoxicity/carcinogenicity. NFRFP exhibited a chemopreventive effect, in all protocols, with damage reduction (% DR) of 75% in the comet test. NFRFP reduced the incidence of aberrant crypt outbreaks by 49.36% in the post-treatment protocol.

CONCLUSIONS

The results suggest the applicability of NFRFP in the human diet due to potential production at an industrial scale and easy technological application in different products, since it could be incorporated in food without altering or causing small changes in final product sensory characteristics.

Evaluation of Antineoplasic Activity of Zingiber Officinale Essential Oil in the Colorectal Region of Wistar Rats

INTRODUCTION

Aberrant Crypt (AC) and Aberrant Crypt Focus (ACF) are considered pre-neoplasic lesions, ranging from hyperplasia to different degrees of dysplasia in the colon. This work aimed to evaluate and quantify the chemopreventive activity of Zingiber officinale essential oil in the colorectal region of Wistar rats.

MATERIALS AND METHODS

We extracted the essential oil from ginger rhizomes and carried out ACF induction, in rats, with 1.2 Dimethylhydrazine (DMH) at a 20 mg/kg dose. The experimental groups were GI (negative control); GII (positive induction control); GIII (DMH + essential oil); GIV (DMH +5-Florouracil) and GV (essential oil). The histological techniques used were methylene blue, hematoxylin-eosin (HE) dyeing, and immunohistochemistry (IHQ).

RESULTS

The major essential oil compounds were citral (17.25%), δ-citral (10.25%), camphene (9.55%), α-zingiberene (7.57%), nerol (6.37%) and plelandrene (6.83%). For the presence of AC or ACF, we did not observe them in GI and GV, while in GII and GIII, they were observed, in high values, in both regions, but only in the distal region, there was a significant difference between them. For GIV, for both regions, there were significant lower numbers of AC when compared to GIII. As observed, with HE, there were hyperplastic and dysplastic ACF in the proximal and distal portions of the colon. For IHQ analyses, there were positively PCNA antibody marked cells in all experimental groups. Yet, there was no significant correlation of mitotic index among them. Moreover, the results of GIII compared to GIV were very similar.

CONCLUSION

In this sense, the Zingiber officinale essential oil has good antioxidant potential because it presents a mixture of monoterpene and sesquiterpene compounds. Thus, it is able to develop a chemoprotective effect, as it presented similar results to the standard drug, showing cell proliferation control.

Epigallocatechin gallate inhibits dimethylhydrazine-induced colorectal cancer in rats

BACKGROUND

Epigallocatechin gallate (EGCG) is a polyhydroxy phenolic compound extracted from tea and its antitumor effect has received widespread attention. We explored the inhibitory effect of EGCG on dimethylhydrazine (DMH)-induced colorectal cancer (CRC) using a rat model, predicted the interaction between EGCG and CRC target genes using a database, and explained the EGCG associated target pathways and mechanisms in CRC.

AIM

To understand the inhibitory mechanisms of EGCG on CRC cell proliferation and identify its pharmacological targets by network pharmacology analysis.

METHODS

DMH (40 mg/kg, s.c., twice weekly for eight weeks) was used to induce CRC in rats. After model establishment, the rats were administered with EGCG (50, 100, or 200 mg/kg, p.o., once daily for eight weeks) and killed 12 and 20 wk after the start of the experiment. Formation of aberrant crypt foci and tumor was studied by histological analysis. Using network pharmacology analysis, candidate and collective targets of EGCG and CRC were identified, and Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses were used to predict the pathways altered by EGCG.

RESULTS

At week 12, high-dose EGCG treatment significantly reduced the tumor formation rate, total number of tumors, cancerous and non-cancerous tumors, tumor volume, ascites formation, and aberrant crypt foci count. At week 20, all three doses of EGCG were effective. Seventy-eight collective targets of EGCG and CRC were identified, of which 28 genes were dysregulated in CRC. Kyoto Encyclopedia of Genes and Genomes and GO analyses showed that the dysregulated genes were enriched in hsa05210 (CRC), hsa04115 (p53 signaling pathway), and hsa04151 (PI3K-Akt signaling pathway), GO:0043124 (negative regulation of I-kappaB kinase/NF-kappaB signaling pathway), GO:0043409 (negative regulation of mitogen-activated protein kinase cascade), and GO:2001244 (positive regulation of intrinsic apoptotic signaling pathway) respectively.

CONCLUSION

EGCG inhibits the formation of DMH-induced CRC by regulating key pathways involved in tumorigenesis.

Lactobacillus acidophilus-Fermented Germinated Brown Rice Suppresses Preneoplastic Lesions of the Colon in Rats

Colorectal cancer (CRC) is a cancer associated with chronic inflammation. Whole grains and probiotics play a protective role against CRC. Fermented grains are receiving increased attention due to their anti-inflammatory and anti-cancer activities. Our previous study found that a combination of germinated brown rice (GBR) with probiotics suppressed colorectal carcinogenesis in rats. However, the cancer-preventive effect of probiotic-fermented GBR has not been reported. This study investigated the preventive effect and possible mechanism of GBR fermented by Lactobacillus acidophilus (FGBR) on colorectal carcinogenesis in rats induced by 1,2-dimethylhydrazine (DMH) and dextran sulfate sodium (DSS). DMH/DSS treatment induced preneoplastic aberrant crypt foci (ACF), elevated serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β, as well as decreased pro-apoptotic Bax expression. GBR and FGBR reduced the primary ACF number and decreased TNF-α, IL-6 and IL-1β levels. GBR and FGBR at the 2.5% level increased pro-apoptotic cleaved caspase-3 and decreased anti-apoptotic B-cell lymphoma 2 (Bcl-2) expressions. FGBR at the 2.5% level further reduced the number of sialomucin-producing ACF (SIM-ACF) and increased Bax expression. These results suggest that FGBR may inhibit preneoplastic lesions of the colon via activating the apoptotic pathway. This fermented rice product may have the potential to be developed as a novel dietary supplement for CRC chemoprevention.

Crypt fusion as a homeostatic mechanism in the human colon

OBJECTIVE

The crypt population in the human intestine is dynamic: crypts can divide to produce two new daughter crypts through a process termed crypt fission, but whether this is balanced by a second process to remove crypts, as recently shown in mouse models, is uncertain. We examined whether crypt fusion (the process of two neighbouring crypts fusing into a single daughter crypt) occurs in the human colon.

DESIGN

We used somatic alterations in the gene cytochrome c oxidase (CCO) as lineage tracing markers to assess the clonality of bifurcating colon crypts (n=309 bifurcating crypts from 13 patients). Mathematical modelling was used to determine whether the existence of crypt fusion can explain the experimental data, and how the process of fusion influences the rate of crypt fission.

RESULTS

In 55% (21/38) of bifurcating crypts in which clonality could be assessed, we observed perfect segregation of clonal lineages to the respective crypt arms. Mathematical modelling showed that this frequency of perfect segregation could not be explained by fission alone (p<10-20). With the rates of fission and fusion taken to be approximately equal, we then used the distribution of CCO-deficient patch size to estimate the rate of crypt fission, finding a value of around 0.011 divisions/crypt/year.

CONCLUSIONS

We have provided the evidence that human colonic crypts undergo fusion, a potential homeostatic process to regulate total crypt number. The existence of crypt fusion in the human colon adds a new facet to our understanding of the highly dynamic and plastic phenotype of the colonic epithelium.

Isolation, characterization and identification of antigenotoxic and anticancerous indigenous probiotics and their prophylactic potential in experimental colon carcinogenesis

Colorectal cancer, the third most commonly diagnosed cancer, is a lifestyle disease where diet and gut microbiome contribute intricately in its initiation and progression. Prophylactic bio-interventions mainly probiotics offer an alternate approach towards reducing or delaying its progression. Therefore, the present study was designed wherein a robust protocol for the isolation, characterization, and identification of indigenous probiotics having antigenotoxic and anticancerous activity was followed along with their prophylactic potential assessment in early experimental colorectal carcinogenesis. Among forty-six isolated lactic acid bacterial strains, only three were selected on the basis of antigenotoxicity against N,N-Dimethyl dihydrazine dihydrochloride and 4-Nitroquinoline 1-oxide and probiotic attributes. All three selected probiotic strains exhibited anticancerous potential as is evident by the reduced Aberrant Crypt Foci, reduced fecal pH, enhanced fecal lactic acid bacteria and altered fecal enzymes (β-glucuronidase, nitroreductase, β-glucosidase) that modulated gut microbiota and microenvironment resulting into restored histoarchitecture of the colon. The results are a clear indicator of the prophylactic potential of selected indigenous probiotics which may be used as an alternative prophylactic biological therapy against colon carcinogenesis particularly in highly susceptible individuals.

Dietary Polyacetylenic Oxylipins Falcarinol and Falcarindiol Prevent Inflammation and Colorectal Neoplastic Transformation: A Mechanistic and Dose-Response Study in A Rat Model

Falcarinol (FaOH) and falcarindiol (FaDOH) are cytotoxic and anti-inflammatory polyacetylenic oxylipins, which are commonly found in the carrot family (Apiaceae). FaOH and FaDOH have previously demonstrated a chemopreventive effect on precursor lesions of colorectal cancer (CRC) in azoxymethane (AOM)-induced rats. The purpose of the present study was to elucidate possible mechanisms of action for the preventive effect of FaOH and FaDOH on colorectal precancerous lesions and to determine how this effect was dependent on dose. Gene expression studies performed by RT-qPCR of selected cancer biomarkers in tissue from biopsies of neoplastic tissue revealed that FaOH and FaDOH downregulated NF-κβ and its downstream inflammatory markers TNFα, IL-6, and COX-2. The dose-dependent anti-neoplastic effect of FaOH and FaDOH in AOM-induced rats was investigated in groups of 20 rats receiving a standard rat diet (SRD) supplemented with 0.16, 0.48, 1.4, 7 or 35 µg FaOH and FaDOH g⁻¹ feed in the ratio 1:1 and 20 rats were controls receiving only SRD. Analysis of aberrant crypt foci (ACF) showed that the average number of small ACF (<7 crypts) and large ACF (>7 crypts) decreased with increasing dose of FaOH and FaDOH and that this inhibitory effect on early neoplastic formation of ACF was dose-dependent, which was also the case for the total number of macroscopic neoplasms. The CRC protective effects of apiaceous vegetables are mainly due to the inhibitory effect of FaOH and FaDOH on NF-κB and its downstream inflammatory markers, especially COX-2.

Efficacy of Difluoromethylornithine and Aspirin for Treatment of Adenomas and Aberrant Crypt Foci in Patients with Prior Advanced Colorectal Neoplasms

Difluoromethylornithine (DFMO), an inhibitor of polyamine synthesis, was shown to act synergistically with a NSAID for chemoprevention of colorectal neoplasia. We determined the efficacy and safety of DFMO plus aspirin for prevention of colorectal adenomas and regression of rectal aberrant crypt foci (ACF) in patients with prior advanced adenomas or cancer. A double-blinded, placebo-controlled trial was performed in 104 subjects (age 46-83) randomized (1:1) to receive daily DFMO (500 mg orally) plus aspirin (325 mg) or matched placebos for one year. All polyps were removed at baseline. Adenoma number (primary endpoint) and rectal ACF (index cluster and total) were evaluated at a one year colonoscopy. ACF were identified by chromoendoscopy. Toxicity was monitored, including audiometry. Eighty-seven subjects were evaluable for adenomas or ACF modulation (n = 62). At one year of treatment, adenomas were detected in 16 (38.1%) subjects in the DFMO plus aspirin arm (n = 42) versus 18 (40.9%) in the placebo arm (n = 44; P = 0.790); advanced adenomas were similar (n = 3/arm). DFMO plus aspirin was associated with a statistically significant reduction in the median number of rectal ACF compared with placebo (P = 0.036). Total rectal ACF burden was also reduced in the treatment versus the placebo arm relative to baseline (74% vs. 45%, P = 0.020). No increase in adverse events, including ototoxicity, was observed in the treatment versus placebo arms. While adenoma recurrence was not significantly reduced by one year of DFMO plus aspirin, the drug combination significantly reduced rectal ACF number consistent with a chemopreventive effect.

Rectal Aberrant Crypt Foci in Humans Are Not Surrogate Markers for Colorectal Cancer Risk

INTRODUCTION

Over the past 20 years, aberrant crypt foci (ACF) have emerged as potential precursors and biomarkers for colorectal cancer (CRC). However, data regarding their molecular pathogenesis, as well as their endoscopic and histological identification, remain inconsistent.

METHODS

A wide cohort of ACF from 100 control subjects and 100 case patients, including patients with adenoma and CRC, were characterized for endoscopic, morphologic, and molecular features.

RESULTS

We observed that among all the endoscopic features evaluated, only the number of large ACF correlated with CRC risk (P = 0.003), whereas the histological classification, as assessed by 2 different pathologists, was inconsistent and did not differ between control and case patients. Moreover, only a few APC and BRAF mutations and no microsatellite instability were detected in our samples. KRAS mutations were detected in 16.3% of ACF samples, which also exhibited increased MGMT hypermethylation. However, none of those events were found to be predictive of CRC risk.

DISCUSSION

Although ACF might be preneoplastic lesions of the colon, they are not suitable biomarkers for assessing CRC progression.

Prevention of colonic neoplasia with polyethylene glycol: A short term randomized placebo-controlled double-blinded trial

Chemoprevention represents an attractive modality against colorectal cancer (CRC) although widespread clinical implementation of promising agents (e.g. aspirin/NSAIDS) have been stymied by both suboptimal efficacy and concerns over toxicity. This highlights the need for better agents. Several groups, including our own, have reported that the over-the-counter laxative polyethylene glycol (PEG) has remarkable efficacy in rodent models of colon carcinogenesis. In this study, we undertook the first randomized human trial to address the role of PEG in prevention of human colonic neoplasia. This was a double-blind, placebo-controlled, three-arm trial where eligible subjects were randomized to 8g PEG-3350 (n = 27) or 17g PEG-3350 (n = 24), or placebo (n = 24; maltodextrin) orally for a duration of six months. Our initial primary endpoint was rectal aberrant crypt foci (ACF) but this was changed during protocol period to rectal mucosal epidermal growth factor receptor (EGFR). Of the 87 patients randomized, 48 completed study primary endpoints and rectal EGFR unchanged PEG treatment. Rectal ACF had a trend suggesting potentially reduction with PEG treatment (pre-post change 1.7 in placebo versus -0.3 in PEG 8+ 17g doses, p = 0.108). Other endpoints (proliferation, apoptosis, expression of SNAIL and E-cadherin), previously noted to be modulated in rodent models, appeared unchanged with PEG treatment in this clinical trial. We conclude that PEG was generally well tolerated with the trial failing to meet primary efficacy endpoints. However, rectal ACFs demonstrated a trend (albeit statistically insignificant) for suppression with PEG. Moreover, all molecular assays including EGFR were unaltered with PEG underscoring issues with lack of translatability of biomarkers from preclinical to clinical trials. This data may provide the impetus for future clinical trials on PEG using more robust biomarkers of chemoprevention.

Trial registration: ClinicalTrials.gov NCT00828984

Naringenin (4,5,7-trihydroxyflavanone) suppresses the development of precancerous lesions via controlling hyperproliferation and inflammation in the colon of Wistar rats

Colon cancer is a world-wide health problem and one of the most dangerous type of cancer, affecting both men and women. Naringenin (4, 5, 7-trihydroxyflavanone) is one of the major flavone glycoside present in citrus fruits. Naringenin has long been used in Chinese's traditional medicine because of its exceptional pharmacological properties and non-toxic nature. In the present study, we investigated the chemopreventive potential of Naringenin against 1,2-dimethyhydrazine (DMH)-induced precancerous lesions, that is, aberrant crypt foci (ACF) and mucin depleted foci (MDF), and its role in regulating the oxidative stress, inflammation and hyperproliferation, in the colon of Wistar rats. Animals were divided into five groups. In groups 3-5, Naringenin was administered at the dose of 50 mg/kg b. wt. orally while in groups 2-4, DMH was administered subcutaneously in the groin at the dose of 20 mg/kg b. wt. once a week for first 5 weeks and animals were euthanized after 10 weeks. Administration of Naringenin ameliorated the development of DMH-induced lipid peroxidation, ROS formation, precancerous lesions (ACF and MDF) and it also reduced the infiltration of mast cells, suppressed the immunostaining of NF-κB-p65, COX-2, i-NOS PCNA and Ki 67 Naringenin treatment significantly attenuated the level of TNF-α and it also prevented the depletion of the mucous layer. Our findings suggest that Naringenin has strong chemopreventive potential against DMH-induced colon carcinogenesis but further studies are warranted to elucidate the precise mechanism of action of Naringenin.

Structural shift of gut microbiota during chemo-preventive effects of epigallocatechin gallate on colorectal carcinogenesis in mice

AIM

To investigate the effect of epigallocatechin gallate (EGCG) on structural changes of gut microbiota in colorectal carcinogenesis.

METHODS

An azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis mouse model was established. Forty-two female FVB/N mice were randomly divided into the following three groups: group 1 (10 mice, negative control) was treated with vehicle, group 2 (16 mice, positive control) was treated with AOM plus vehicle, and group 3 (16 mice, EG) was treated with AOM plus EGCG. For aberrant crypt foci (ACF) evaluation, the colons were rapidly took out after sacrifice, rinsed with saline, opened longitudinally, laid flat on a polystyrene board, and fixed with 10% buffered formaldehyde solution before being stained with 0.2% methylene blue in saline. For tumor evaluation, the colon was macroscopically inspected and photographed, then the total number of tumors was enumerated and tumor size measured. For histological examination, the fixed tissues were paraffin-embedded and sectioned at 5 mm thickness. Microbial genomic DNA was extracted from fecal and intestinal content samples using a commercial kit. The V4 hypervariable regions of 16S rRNA were PCR-amplified with the barcoded fusion primers. Using the best hit classification option, the sequences from each sample were aligned to the RDP 16S rRNA training set to classify the taxonomic abundance in QIIME. Statistical analyses were then performed.

RESULTS

Treatment of mice with 1% EGCG caused a significant decrease in the mean number of ACF per mouse, when compared with the model mice treated with AOM/DSS (5.38 ± 4.24 vs 13.13 ± 3.02, P < 0.01). Compared with the positive control group, 1% EGCG treatment dependently decreased tumor load per mouse by 85% (33.96 ± 6.10 vs 2.96 ± 2.86, respectively, P < 0.01). All revealed that EGCG could inhibit colon carcinogenesis by decreasing the number of precancerous lesions as well as solid tumors, with reduced tumor load and delayed histological progression of CRC. During the cancerization, the diversity of gut microbiota increased, potential carcinogenic bacteria such as Bacteroides were enriched, and the abundance of butyrate-producing bacteria (Clostridiaceae, Ruminococcus, etc.) decreased continuously. In contrast, the structure of gut microbiota was relatively stable during the intervention of EGCG on colon carcinogenesis. Enrichment of probiotics (Bifidobacterium, Lactobacillu, etc.) might be a potential mechanism for EGCG’s effects on tumor suppression. Via bioinformatics analysis, principal coordinate analysis and cluster analysis of the tumor formation process, we found that the diversity of gut microbiota increased in the tumor model group while that in the EGCG interfered group (EG) remained relatively stable.

CONCLUSION

Gut microbiota imbalance might be a potential mechanism for the prevention of malignant transformation by EGCG, which is significant for diagnosis, treatment, prognosis evaluation, and prevention of colorectal cancer.

Exacerbation of colon carcinogenesis by Blastocystis sp

Colorectal cancer (CRC) is one the most commonly diagnosed cancers worldwide and the number is increasing every year. Despite advances in screening programs, CRC remains as the second leading cause of cancer deaths in the United States. Oxidative stress plays an important role in the molecular mechanisms of colorectal cancer (CRC) and has been shown to be associated with Blastocystis sp., a common intestinal microorganism. In the present study, we aimed to identify a role for Blastocystis sp. in exacerbating carcinogenesis using in vivo rat model. Methylene blue staining was used to identify colonic aberrant crypt foci (ACF) and adenomas formation in infected rats whilst elevation of oxidative stress biomarker levels in the urine and serum samples were evaluated using biochemical assays. Histological changes of the intestinal mucosa were observed and a significant number of ACF was found in Blastocystis sp. infected AOM-rats compared to the AOM-controls. High levels of urinary oxidative indices including advanced oxidative protein products (AOPP) and hydrogen peroxide were observed in Blastocystis sp. infected AOM-rats compared to the uninfected AOM-rats. Our study provides evidence that Blastocystis sp. has a significant role in enhancing AOM-induced carcinogenesis by resulting damage to the intestinal epithelium and promoting oxidative damage in Blastocystis sp. infected rats.

Genistein regulates tumor microenvironment and exhibits anticancer effect in dimethyl hydrazine-induced experimental colon carcinogenesis

Colon cancer is one of the leading causes of cancer mortality, worldwide. Cancer stem cells are attractive targets for therapeutic interventions since their abnormal growth may trigger tumor initiation, progression, and recurrence. Colon cancer in rats were induced with 1, 2-dimethyl hydrazine (DMH) and treated with genistein, an isoflavone rich in the soy food products, which also possesses various biological activities. Genistein treatment regulates enzymatic and non-enzymatic anti-oxidants in the DMH-induced colonic tissue microenvironment. Alcian blue staining in colonic tissue reveals that mucin secretion was found to be depleted in DMH-induced group of animals. The alterations were normalized in the genistein-treated groups. Also, the mast cell population and collagen deposition were reduced as compared to induced group. Genistein treatment reduces the prognostic marker Argyrophilic nuclear organizer region (AgNOR) and proliferating cell nucleolar antigen (PCNA) in DMH-induced group of rats. DMH administration induces oxidative stress, whereas genistein activates nuclear factor-erythroid 2 related factor 2 (Nrf-2) and its downstream target hemoxygenase-1 (HO-1). Colonic stem cell marker protein CD133, CD44, and β-catenin expressions were found to be increased in DMH-induced group of animals as compared to control group of rats. Genistein treatment suppressed the expression of these stem cell markers suggesting rapid dysfunctional activation and proliferation of colonic stem cell-induced by DMH. The results of this study indicate that genistein administration in rats restored the colonic niche that was damaged by DMH and inhibits colon cancer progression. © 2016 BioFactors, 42(6):623-637, 2016.

Hydrolysed inulin alleviates the azoxymethane-induced preneoplastic aberrant crypt foci by altering selected intestinal microbiota in Sprague-Dawley rats

Context Inulin, a non-digestible carbohydrate isolated from Helianthus tuberosus L. (Asteraceae), has been shown to alter the gut beneficial bacteria including Lactobacillus spp. and Bifidobacteria. Inulin also influences the activities of intestinal microbiota that could prevent the colon cancer development. Objective This study determines the effect of hydrolysed inulin with different degrees of polymerisation on alteration of intestinal microbiota and their activities on azoxymethane (AOM)-induced preneoplastic aberrant crypt foci (ACF) in rats. Materials and methods Seventy-two male Sprague-Dawley rats were randomly divided into six groups (three control and three AOM-treated groups) and the animal were fed with either a normal diet or diet containing 10% of long-chain inulin (InuL) or short-chain inulin (InuS), respectively, for 17 weeks. Colon cancer was induced in rats by injecting AOM subcutaneously at the 8th and 9th week of the study period. At the end of the experiment, cecal contents of rats were examined for selected microbiota, organic acids, putrefactive compounds and microbial enzymes. ACF formation was microscopically examined. Results The inulin diets significantly increased the weight and decreased the pH of the caecal content. The rats fed with InuL-supplemented diet showed approximately 2.9- and 6.8-fold increases in the biomass of Lactobacillus spp. and Bifidobacteria, respectively. Naive and AOM-treated rats fed with inulin-supplemented diet showed ∼1.3- and ∼2.2-fold decreases in the biomass of Escherichia coli and Salmonella enterica serovar Typhi, respectively. Inulins significantly decreased the colonic concentration of phenol, p-cresol and indole. Reduction in the activity of microbial enzymes such as β-glucuronidase, azoreductase and nitroreductase were observed in inulin-treated animals. Reduction in the ACF formation has been observed in inulin-treated groups. Discussion and conclusion The present study demonstrates that dietary administration of inulin reduces the formation of preneoplastic lesions in the colon, possibly by altering the microecology and microbial activities on carcinogenesis.

Novel Combination of Prebiotics Galacto-Oligosaccharides and Inulin-Inhibited Aberrant Crypt Foci Formation and Biomarkers of Colon Cancer in Wistar Rats

The selectivity and beneficial effects of prebiotics are mainly dependent on composition and glycosidic linkage among monosaccharide units. This is the first study to use prebiotic galacto-oligosaccharides (GOS) that contains β-1,6 and β-1,3 glycosidic linkages and the novel combination of GOS and inulin in cancer prevention. The objective of the present study is to explore the role of novel GOS and inulin against various biomarkers of colorectal cancer (CRC) and the incidence of aberrant crypt foci (ACF) in a 1,2-dimethyl hydrazine dihydrochloride (DMH)-induced rodent model. Prebiotic treatments of combined GOS and inulin (57 mg each), as well as individual doses (GOS: 76-151 mg; inulin 114 mg), were given to DMH-treated animals for 16 weeks. Our data reveal the significant preventive effect of the GOS and inulin combination against the development of CRC. It was observed that inhibition of ACF formation (55.8%) was significantly (p ≤ 0.05) higher using the GOS and inulin combination than GOS (41.4%) and inulin (51.2%) treatments alone. This combination also rendered better results on short-chain fatty acids (SCFA) and bacterial enzymatic activities. Dose-dependent effects of prebiotic treatments were also observed on cecum and fecal bacterial enzymes and on SCFA. Thus, this study demonstrated that novel combination of GOS and inulin exhibited stronger preventive activity than their individual treatments alone, and can be a promising strategy for CRC chemoprevention.

Detection and Characterization of Flat Aberrant Crypt Foci (Flat ACF) in the Novel A/J Min/+ Mouse

BACKGROUND/AIM

Flat aberrant crypt foci (flat ACF) and mucin-depleted foci (MDF) have previously been described as preneoplastic colonic lesions. We used the novel A/J Min/+ mouse model, that demonstrates extensive spontaneous colon carcinogenesis to refine the method of detection of flat ACF and further characterize and define them as early lesions by histological examination and comparison with MDF.

MATERIALS AND METHODS

Colons were stained with methylene blue (MB) for flat ACF detection and restained with high-iron diamine-alcian blue (HID-AB) for MDF detection.

RESULTS

Optimal flat ACF recognition required at least 24 h of storage post-MB staining and adherence to a set of characteristics. The fraction of flat ACF corresponding with MDF was 93%. Flat ACF/MDF displayed the same picture of severe dysplasia, lack of mucus and goblet cells and accumulation of cytoplasmic β-catenin.

CONCLUSION

The easily detectable flat ACF are reliable surface biomarkers of Apc-driven colon carcinogenesis.

Intestinal Tumor Development in C57BL/6J-ApcMin/+ Mice Expressing Human Sulphotransferases 1A1 and 1A2 After Oral Exposure to 2,5-Dimethylfuran

BACKGROUND

2,5-dimethylfuran (DMF) is formed during heating of foods. Following side chain hydroxylation, DMF could be a substrate for human sulphotransferases (SULTs), which may lead to formation of a DNA reactive electrophile. Only few conflicting in vitro and no in vivo studies on DMF currently exist.

MATERIALS AND METHODS

The tumorigenic potential of DMF was studied in multiple intestinal neoplasia Apc(Min/+) (Min) mice that are sensitive to intestinal carcinogenesis and express hSULTs 1A1 and 1A2 (Min/hSULT). Min and Min/hSULT mice were orally exposed to DMF for six weeks.

RESULTS

The intestinal tumor development of untreated female Min/hSULT mice was significantly lower compared to that of untreated Min females. No such effects of hSULTs were seen in males. DMF had a weak tumorigenic potential in the colon of female Min/hSULT mice, but not in males. Tumor development in Min mice was not affected.

CONCLUSION

Overall, the tumorigenic potential of DMF in a metabolically competent mouse model was not convincing.

Brewers' rice attenuated aberrant crypt foci developing in colon of azoxymethane-treated rats

Brewers' rice is one of abundant agricultural waste products in the rice industry. The present study is designed to investigate the potential of brewers' rice to inhibit the development of aberrant crypt foci (ACF) in colon of azoxymethane (AOM)-treated rats. The effects on the attenuation of hepatic toxicity and kidney function enzymes were also evaluated. Male Sprague-Dawley rats were randomly divided into five groups: (G1) normal; (G2) AOM alone; and (G3), (G4), and (G5), which were AOM fed with 10%, 20%, and 40% (w/w) of brewers' rice, respectively. The rats in group 2-5 were injected intraperitoneally with AOM (15 mg/kg body weight) once weekly for two weeks. After 8 weeks of treatment,the total number of ACF/colon and the number of ACF in the distal and middle colon were significantly reduced in all treatment groups compared to G2 (p<0.05). Brewers' rice decreased the number of ACF with dysplastic morphology in a dose-dependent manner. Alkaline phosphatase (ALP) level in G5 was significantly lower compared to the G2 (p<0.05). In conclusion, this study found the potential value of brewers' rice in reducing the risk of cancer susceptibility in colon.

Effect of sinapic acid on 1,2 dimethylhydrazine induced aberrant crypt foci, biotransforming bacterial enzymes and circulatory oxidative stress status in experimental rat colon carcinogenesis

AIM

This study was aimed to investigate the effect of sinapic acid (SA) on 1,2-dimethylhydrazine (DMH) induced experimental rat colon carcinogenesis.

MATERIALS AND METHODS

Rats were assorted into six groups, group 1 served as control, group 2 received SA (80 mg/kg b.w.) post orally every day until the end of the experimental period of 16 weeks, groups 3-6 rats were injected DMH (20 mg/kg b.w.) subcutaneously once a week for first four weeks. In addition, groups 4-6 rats received different doses of SA (20, 40 and 80 mg/kg b.w.).

RESULTS

Our results showed that DMH induced rats revealed significantly increased ACF development and multiplicity, which were significantly inhibited on supplementation with SA. Moreover, elevated levels/activities of circulatory oxidative stress markers, faecal and colonic mucosal bacterial enzymes were observed in DMH exposed rats, which were diminished on supplementation with SA.

CONCLUSION

Overall, our findings revealed that supplementation with SA offers significant protection against DMH induced rat colon carcinogenesis and the effect of SA at the dose of 40 mg/kg b.w. was more pronounced as compared to the other two doses. (Tab.5, Fig. 3, Ref. 46)

Early detection of colorectal cancer relapse by infrared spectroscopy in "normal" anastomosis tissue

Colorectal cancer is one of the most aggressive cancers usually occurring in people above the age of 50 years. In the United States, colorectal cancer is the third most diagnosed cancer. The American Cancer Society has estimated 96,830 new cases of colon cancer and 40,000 new cases of rectal cancer in 2014 in the United States. According to the literature, up to 55% of colorectal cancer patients experience a recurrence within five years from the time of surgery. Relapse of colorectal cancer has a deep influence on the quality of patient life. Infrared (IR) spectroscopy has been widely used in medicine. It is a noninvasive, nondestructive technique that can detect changes in cells and tissues that are caused by different disorders, such as cancer. Abnormalities in the colonic crypts, which are not detectable using standard histopathological methods, could be determined using IR spectroscopic methods. The IR measurements were performed on formalin-fixed, paraffin-embedded colorectal tissues from eight patients (one control, four local recurrences, three distant recurrences). A total of 128 crypts were measured. Our results showed the possibility of differentiating among control, local, and distant recurrence crypts with more than a 92% success rate using spectra measured from the crypts' middle sites.

The chemopotential effect of Annona muricata leaves against azoxymethane-induced colonic aberrant crypt foci in rats and the apoptotic effect of Acetogenin Annomuricin E in HT-29 cells: a bioassay-guided approach

Annona muricata has been used in folk medicine for the treatment of cancer and tumors. This study evaluated the chemopreventive properties of an ethyl acetate extract of A. muricata leaves (EEAML) on azoxymethane-induced colonic aberrant crypt foci (ACF) in rats. Moreover, the cytotoxic compound of EEAML (Annomuricin E) was isolated, and its apoptosis-inducing effect was investigated against HT-29 colon cancer cell line using a bioassay-guided approach. This experiment was performed on five groups of rats: negative control, cancer control, EEAML (250 mg/kg), EEAML (500 mg/kg) and positive control (5-fluorouracil). Methylene blue staining of colorectal specimens showed that application of EEAML at both doses significantly reduced the colonic ACF formation compared with the cancer control group. Immunohistochemistry analysis showed the down-regulation of PCNA and Bcl-2 proteins and the up-regulation of Bax protein after administration of EEAML compared with the cancer control group. In addition, an increase in the levels of enzymatic antioxidants and a decrease in the malondialdehyde level of the colon tissue homogenates were observed, suggesting the suppression of lipid peroxidation. Annomuricin E inhibited the growth of HT-29 cells with an IC50 value of 1.62 ± 0.24 μg/ml after 48 h. The cytotoxic effect of annomuricin E was further substantiated by G1 cell cycle arrest and early apoptosis induction in HT-29 cells. Annomuricin E triggered mitochondria-initiated events, including the dissipation of the mitochondrial membrane potential and the leakage of cytochrome c from the mitochondria. Prior to these events, annomuricin E activated caspase 3/7 and caspase 9. Upstream, annomuricin E induced a time-dependent upregulation of Bax and downregulation of Bcl-2 at the mRNA and protein levels. In conclusion, these findings substantiate the usage of A. muricata leaves in ethnomedicine against cancer and highlight annomuricin E as one of the contributing compounds in the anticancer activity of A. muricata leaves.

Chemopreventive effects of rosmarinic acid on rat colon carcinogenesis

Rosmarinic acid (RA) is a polyphenolic compound that shows a number of interesting biological activities, such as antiapoptotic, antifibrotic, antioxidant, hepatoprotective, antineurodegenerative, and anti-inflammatory properties. The aim of this study was to investigate the ability of RA to prevent 1,2-dimethylhydrazine (DMH)-induced primary DNA damage and aberrant crypt foci (ACF) in Wistar rat colon. The animals were treated by gavage with doses of 4, 8, and 16 mg/kg body weight/day. Next, the animals received a single subcutaneous injection of 40 mg/kg DMH and were killed 4 h later for the evaluation of DNA damage using the comet assay. In addition, two doses of 40 mg/kg DMH were administered weekly for 2 weeks and the animals were killed 2 weeks after the last injection for the evaluation of ACF formation in rat colon. The results showed that RA exerted no genotoxic/carcinogenic effects. Treatment with different doses of RA combined with DMH led to a significant reduction in the extent of DNA damage and in the frequency of ACF compared with animals treated with DMH alone. These findings suggest that RA reduces DNA damage and suppresses the formation of ACF.

Diabetes promotes DMH-induced colorectal cancer by increasing the activity of glycolytic enzymes in rats

The objective of the present study was to investigate the association between diabetes mellitus and colorectal carcinogenesis as well as the possible mechanism involved in this interaction. Diabetes rat models were induced with a low dose of STZ followed by a low dose of DMH to induce colorectal cancer. The formation of ACF in the colon and the incidence, number and size of tumors were measured. The activity of glycolytic enzymes in colonic tissues was also measured. The results demonstrated that both the total number of ACF and the number of foci that contain a different number of crypts were increased in diabetic rats. At the end of the experimental treatment, the incidence, number and size of tumors were also increased in diabetic rats. Overall, these data indicated that diabetes increased the risk of colorectal cancer. The activity of HK and PK in colonic tissues was increased in diabetic rats, whereas the activity of PDH was decreased. In addition, the activities of these enzymes in intratumor were higher than that of in peritumor. These data indicated that the high rate of glycolysis may play a role in colorectal carcinogenesis in diabetic rats.

Quantification of crypt and stem cell evolution in the normal and neoplastic human colon

Human intestinal stem cell and crypt dynamics remain poorly characterized because transgenic lineage-tracing methods are impractical in humans. Here, we have circumvented this problem by quantitatively using somatic mtDNA mutations to trace clonal lineages. By analyzing clonal imprints on the walls of colonic crypts, we show that human intestinal stem cells conform to one-dimensional neutral drift dynamics with a "functional" stem cell number of five to six in both normal patients and individuals with familial adenomatous polyposis (germline APC(-/+)). Furthermore, we show that, in adenomatous crypts (APC(-/-)), there is a proportionate increase in both functional stem cell number and the loss/replacement rate. Finally, by analyzing fields of mtDNA mutant crypts, we show that a normal colon crypt divides around once every 30-40 years, and the division rate is increased in adenomas by at least an order of magnitude. These data provide in vivo quantification of human intestinal stem cell and crypt dynamics.

The effect of dietary oils on the development of aberrant crypt foci, bifidobacteria and fecal pH

The present study investigated the relationship between intestinal bifidobacteria and intake of commercial dietary oils of different fatty acids compositions on the development of aberrant crypt foci (ACF). Wistar rats were grouped according to diet and treatment with dimethylhydrazine (DMH): standard diet (CN), canola oil (CAN), olive oil (OLI), corn oil (COR), standard diet and DMH (CNDMH), canola oil and DMH (CANDMH), olive oil and DMH (OLIDMH) and corn oil and DMH (CORDMH). Diets and DMH did not alter the amount of bifidobacteria, fecal pH and serum total cholesterol level. DMH-treated groups had lower serum triglyceride levels compared to respective controls without DMH. Olive and corn oil diets resulted in higher hepatic cholesterol levels than standard diet under treatment with DMH. The numbers of ACF/field and cell proliferation were lower under treatment with CANDMH and OLIDMH, suggesting a protective effect of these oils on colorectal carcinogenesis.

[Metaplasic Paneth cells in ulcerative colitis]

BACKGROUND

Paneth cells are normally present in small intestine, but its appearance in other areas of the gastrointestinal tract is related to chronic inflammatory processes.

MATERIAL AND METHODS

In our study we retrospectively examined 29 patients with diagnosis of ulcerative colitis, from the files of Instituto de Histopatología de Rosario, and from the casuistry of two authors (O.B. and P.S.M.), during two years. Biopsies corresponded to rectal or sigmoid mucosa and were stained with H.E.

RESULTS

Distal Paneth cells in rectum and/or sigmoid colon were found in 60% of patients. This finding was related to the time of evolution of the disease (median 7 years for patients with Paneth cells and 3 years for patients without Paneth cells). With more time of evolution, there were more number of affected crypts and more number of Paneth cells. Some of the patients with longer evolution had 2-5 crypts with Paneth cells (up to 11 Paneth cells). When the time of evolution of the disease was longer, we found an irregular distribution of Paneth cells, with migration from the depth of the crypt to highest crypt levels. There was a relationship between the number of Paneth cells and the degree of leukocyte infiltration of the mucosa.

CONCLUSIONS

We observed a direct correlation of the presence of Paneth cells with the time of evolution of the disease and with the leukocyte infiltration of the mucosa.

Determination using synchrotron radiation-based Fourier transform infrared microspectroscopy of putative stem cells in human adenocarcinoma of the intestine: corresponding benign tissue as a template

The epithelial-cell layer lining the two morphologically and functionally distinct segments of the mammalian intestinal tract, small intestine, and colon is constantly being renewed. This renewal is necessitated by a harsh lumen environment and is hypothesized to be driven by a small population of stem cells (SCs) that are believed to reside at the base of intestinal crypts. A lack of specific markers has hampered previous attempts to identify their exact location. We obtained tissue sections containing small intestine and colon crypts derived from normal (benign) or adenocarcinoma (AC) human intestine. The samples were floated onto BaF2 windows and analyzed using synchrotron radiation-based Fourier transform infrared microspectroscopy via an aperture size of 10 × 10 μm. Derived infrared (IR) spectral data was then analyzed using principal component analysis and/or linear discriminant analysis. Hypothesized cell types (as a function of aperture location along the length of individual crypts) within benign crypts were classed based on exploratory unsupervised IR spectral point clustering. Scores plots derived from individual small intestine crypts consistently generated one or two distinct spectra that clustered away from the remaining cell categories; these were retrospectively classed as "distinct base region" spectra. In these plots, a clear progression of locations along crypt lengths designated as from putative stem cells (SCs) to transit-amplifying (TA) cells to terminally differentiated (TD) cells was observed in benign small intestine and colon crypts. This progression of spectral points was crypt specific, pointing away from a unifying cell lineage model in human intestinal crypts. On comparison of AC-derived spectra versus corresponding benign, a subpopulation of AC-derived spectra suggested a putative SC-like spectral fingerprint; remaining IR spectra were classed as exhibiting TA cell-like or TD cell-like spectral characteristics. These observations could point to a cancer SC phenotype; an approach capable of identifying their in situ location has enormous therapeutic applications.

Crypt dysplasia in Barrett's oesophagus shows clonal identity between crypt and surface cells

Epithelial dysplasia is an important histological diagnosis signifying the presence of pre-invasive disease, usually needing intervention. However, the specific genetic changes responsible for the induction of this phenotypic change are unknown. Moreover, recent reports indicate that the dysplastic phenotype may not be immutable: in basal crypt dysplasia (CD), unequivocal dysplastic changes are seen in the crypts in Barrett's oesophagus and other pre-invasive lesions in the gastrointestinal tract, but the upper crypts and surface epithelium associated with these dysplastic crypts show the definitive morphology of a differentiated epithelium. The genotypic relationship between CD and the differentiated surface epithelium is presently unclear. We obtained 17 examples of CD: the lower and upper crypts and surface epithelium were differentially laser-microdissected from formalin-fixed, paraffin-embedded sections and mutations were sought in tumour suppressor genes frequently associated with progression in Barrett's oesophagus. We found two patients who both showed a c. C238T mutation in the CDKN2A (CDKN2AInk4A) gene and where the precise microanatomical relationships could be discerned: this mutation was present in both the CD at the crypt base and in the upper crypt and surface epithelium. We conclude that, in CD, the dysplastic basal crypt epithelium and the upper crypt and surface epithelium show clonal CDKN2A mutations, thus showing definitively that the surface epithelium is derived from the dysplastic crypt epithelium: the dysplastic phenotype is therefore not fixed and can be reversed. The mechanism of this change is unclear but may be related to the possibility that dysplastic cells can, probably early in their progression, respond to differentiation signals. However, it is also clear that a heavy mutational burden can be borne by crypts in the gastrointestinal tract without the development of phenotypic dysplasia. We are evidently some way from understanding the plasticity and the genotypic correlates of the dysplastic phenotype.

Risk of colonic cancer is not higher in the obese Lep(ob) mouse model compared to lean littermates

Epidemiological data suggest that obesity increases the risk of colorectal cancer in humans. Given that diet-induced obesity mouse models verified the epidemiological data, the present study aimed to determine whether obese C57BL/6J-Lep(ob) male mice (a different obesity in vivo model) were at greater risk of colonic cancer than their lean male littermates. Risk of colonic tumorigenesis was assessed by numbers of aberrant crypts, aberrant crypt foci and colonic tumors. Proliferation of the colonic epithelia was assessed histochemically following administration of BrdU. Availability of the procarcinogen, azoxymethane (AOM) to target tissues was assessed by quantifying via HPLC plasma AOM concentrations during the 60 min period following AOM injection. When obese and lean mice were injected with azoxymethane (AOM) at doses calculated to provide equivalent AOM levels per kg lean body mass, obese animals had significantly fewer aberrant crypts/colon and fewer aberrant crypt foci/colon than the lean animals. Tumors were identified in the colonic mucosa of lean (4 tumors in 14 mice) but not obese (0 tumors in 15 mice) mice. Colonic cell proliferation was not significantly different for obese and lean mice. Because these results were unexpected, plasma AOM concentrations were measured and were found to be lower in the obese than lean mice. When plasma AOM levels were comparable for the lean and obese mice, the Lep(ob) mice continued to have significantly fewer aberrant crypt foci/colon than the lean mice, but differences were not statistically different for aberrant crypts/colon. Interestingly, obese Lep(ob) mice did not exhibit increased risk of colonic cancer as expected. Instead, Lep(ob) mice exhibited equivalent or lower risk of colon cancer when compared to the lean group. These results taken together with in vivo results from diet-induced obesity studies, imply that leptin may be responsible for the increased risk of colon cancer associated with obesity.

Glycyrrhizic acid suppresses the development of precancerous lesions via regulating the hyperproliferation, inflammation, angiogenesis and apoptosis in the colon of Wistar rats

Background

Colon carcinogenesis is a multistep process and it emanates from a series of molecular and histopathological alterations. Glycyrrhizic acid (GA) is a natural and major pentacyclic triterpenoid glycoside of licorice roots extracts. It has several pharmacological and biological properties such as anti-inflammatory, anti-viral, and anti-cancer. In the present study, we investigated the chemopreventive potential of GA against 1,2-dimethyhydrazine (DMH)-induced precancerous lesions i.e., aberrant crypt foci (ACF) and mucin depleted foci (MDF), and its role in regulating the hyperproliferation, inflammation, angiogenesis and apoptosis in the colon of Wistar rats.

Methods

Animals were divided into 5 groups. In group III, IV and V, GA was administered at the dose of 15 mg/kg b. wt. orally while in group II, III and IV, DMH was administered subcutaneously in the groin at the dose of 20 mg/kg b.wt once a week for first 5 weeks and animals were euthanized after 9 weeks.

Results

GA supplementation suppressed the development of precancerous lesions and it also reduced the infiltration of mast cells, suppressed the immunostaining of Ki-67, NF-kB-p65, COX-2, iNOS and VEGF while enhanced the immunostaining of p53, connexin-43, caspase-9 and cleaved caspase-3. GA treatment significantly attenuated the level of TNF-α and it also reduced the depletion of the mucous layer as well as attenuated the shifting of sialomucin to sulphomucin.

Conclusion

Our findings suggest that GA has strong chemopreventive potential against DMH-induced colon carcinogenesis but further studies are warranted to elucidate the precise mechanism of action of GA.

Modulatory efficacy of rosmarinic acid on premalignant lesions and antioxidant status in 1,2-dimethylhydrazine induced rat colon carcinogenesis

Colorectal cancer is one of the leading causes of cancer related deaths in Western countries and is becoming increasingly common in Asia. Rosmarinic acid (RA), one of the major components of polyphenol possesses attractive remedial features. The purpose of this study is to investigate the possible chemopreventive mechanism of action of RA against 1,2-dimethylhydrazine (DMH) induced rat colon carcinogenesis by evaluating the circulatory antioxidant status and colonic bacterial enzymes activities. Additionally, we analyzed the aberrant crypt foci (ACF) formation and multiplicity in the colon of experimental groups. Wistar male rats were divided into six groups. Group 1 was control rats, group 2 rats received RA (10 mg/kg b.w., p.o. everyday), rats in groups 3-6 received DMH (20 mg/kg b.w., s.c.) for the first 4 weeks. In addition to DMH, groups 4-6 received 2.5, 5, and 10 mg/kg b.w. RA respectively. The results revealed that supplementation with RA significantly reduced the formation of ACF and ACF multiplicity in DMH treated rats. Moreover RA supplementation prevented the alterations in circulatory antioxidant enzymes and colonic bacterial enzymes activities. Overall, our results showed that all three doses of RA inhibited carcinogenesis, though the effect of the intermediary dose of 5 mg/kg b.w. was more pronounced.

Glucagon-like peptide-1 (GLP-1) receptor agonism or DPP-4 inhibition does not accelerate neoplasia in carcinogen treated mice

INTRODUCTION

Glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) are secreted in parallel from the intestinal endocrine cells after nutrient intake. GLP-1 is an incretin hormone and analogues are available for the treatment of type 2 diabetes mellitus (T2DM). GLP-2 is an intestinal growth hormone and is shown to promote growth of colonic adenomas in carcinogen treated mice. Both peptides are degraded by dipeptidyl peptidase-4 (DPP-4) into inactive metabolites. DPP-4 inhibitors are therefore also in use for treatment of T2DM. It is possible that DPP-4 inhibition by enhancing the exposure of endogenous GLP-2 to the intestinal epithelia also might mediate growth and promote neoplasia. We investigated the intestinal growth effect of the GLP-1 receptor agonists (GLP-1 RAs) (liraglutide and exenatide) and DPP-4 inhibition (sitagliptin) in healthy mice. We also investigated the potential tumour promoting effect of liraglutide and sitaglitin in the colon of carcinogen treated mice. We used GLP-2 as a positive control.

METHODS

For the growth study we treated healthy CD1 mice with liraglutide (300 μg×2), exenatide (12.5 μg×2) or vehicle subcutaneously and sitagliptin (8mg×2) or water by oral gavage for 10 or 30 days. We measured intestinal weight, cross sectional area, villus height and crypt depth. For the tumour study we treated carcinogen treated mice (1,2 dimethylhydrazine 21 mg/kg/week for 12 weeks) with liraglutide (300 μg×2), Gly2-GLP-2 (25 μg×2) or vehicle subcutaneously and sitagliptin (8 mg×2) or water by oral gavage for 45 days. We counted aberrant crypt foci (ACF), mucin depleted foci (MDF) and adenomas in the colon. Using COS-7 cells transfected with a GLP-2 receptor, we tested if liraglutide or exenatide could activate the receptor.

RESULTS

In the 10 days experiment the relative small intestinal weight was increased with 56% in the liraglutide group (p<0.001) and 26% in the exenatide group (p<01) compared with vehicle treated mice. After 30 days of treatment, liraglutide did also increase the colonic weight (p<0.01). By morphometry the growth pattern mimicked that of GLP-2. Sitagliptin treatment had only a minor effect. In the carcinogen treated mice we found no increase of ACF in any of the groups, the numbers of MDF and adenomas after liraglutide and sitagliptin treatments were similar to their respective control groups. Neither liraglutide nor exenatide stimulated cAMP release from GLP-2 receptor transfected cells.

CONCLUSION

Both GLP-1 analogues were potent growth stimulators of the healthy mouse intestine. No agonism was found for GLP-1 RAs at the GLP-2 receptor. Despite of the growth effect, liraglutide did not promote dysplasia in the colon. Sitagliptin did not show any tumour promoting effects, and non considerable growth effects.

Loss of expression of DNA mismatch repair proteins in aberrant crypt foci identified in vivo by magnifying colonoscopy in subjects with hereditary nonpolyposic and sporadic colon rectal cancer

PURPOSE

The aims of this study are to characterize the frequency, density, and distribution of aberrant crypt foci (ACF) and its histological features and to determine the frequency of loss of expression of DNA mismatch repair (MMR) proteins of subjects with hereditary nonpolyposic colorectal cancer (HNPCC) and sporadic colon rectal cancer (CRC).

METHODS

Patients with HNPCC, first-degree relatives of subjects with HNPCC, sporadic CRC, and average risk subjects of sporadic CRC were included prospectively. Total colonoscopy with chromoendoscopy using methylene blue 0.5% and magnification in the right colon (cecum and 20 cm of the ascending colon) and in the left colon (rectum) was performed; loss of expression of MLH1 and MSH2 was evaluated by immunohistochemistry in confirmed ACF.

RESULTS

Fifty-two subjects were included. Thirty-eight of the 119 ACF detected by endoscopy were biopsied. In 14 of the 38 specimens (36.8%), ACF were confirmed by histology (Cohen's kappa, 0.44). In subjects with HNPCC, ACF were identified more frequently in the right segment of the colon than in the left (73.1% vs. 26%); in contrast, ACF predominated in the left segment of the colon (89.3% vs. 10.6%) in subjects with sporadic CRC. There was a loss of MLH1 expression in ACF in subjects with HNPCC.

CONCLUSIONS

In HNPCC, we found a greater density of ACF in the right colon, and in sporadic CRC, greater density in the left. ACF present loss in the expression of DNA MMR protein and can be used as an early marker in patients with a risk of HNPCC in whom carcinogenesis appears to be accelerated.

Ellagic acid modulates antioxidant status, ornithine decarboxylase expression, and aberrant crypt foci progression in 1,2-dimethylhydrazine-instigated colon preneoplastic lesions in rats

Chemoprevention offers a novel approach to control the incidence of colorectal cancer (CRC), which is a fatal cause of malignancies in both Western and Asia countries. Ornithine decarboxylase (ODC) functions as a cell transition factor by regulating the biosynthesis of polyamines, which, allied with aberrant crypt foci (ACF) proliferation, cause early lesions of CRC. This study exemplifies the chemopreventive efficacy of ellagic acid (EA) in 1,2-dimethylhydrazine (DMH) initiated CRC in rats. Subcutaneous injection of DMH (40 mg/kg body weight twice a week for 2 weeks) to the rats resulted in elevated expression of ODC, a genetic marker for CRC, and its transcription factor myelocytomatosis oncogene (c-myc). Furthermore, increased levels of lipid peroxidation and hydroperoxides with diminished levels of antioxidants including superoxide dismutase, catalase, and reduced glutathione were also observed in the tissues of DMH-intoxicated rats. Oral supplementation of EA significantly influences maintenance of antioxidant status and transcriptional inactivation of ODC expression, reducing ACF proliferation and/or progression, thus signifying the chemopreventive efficacy of EA against CRC.

Regulation of CYP24 splicing by 1,25-dihydroxyvitamin D₃ in human colon cancer cells

CYP24 is a well-established vitamin D receptor (VDR) target gene. The active VDR ligand 1,25(OH)₂D₃ regulates its own catabolism by increasing CYP24 expression. It is well known that in the presence of 1,25(OH)₂D₃, VDR binds to VDREs in the promoter region of CYP24 and initiates CYP24 transcription. However, little is known about the role of 1,25(OH)₂D₃ in the posttranscriptional modulation of CYP24. In this study, we investigated the functional significance of 1,25(OH)₂D₃ in CYP24 RNA splicing in colon cancer cells. Using RT-PCR, we found that 1,25(OH)₂D₃ actively induces CYP24 splicing in a time-dependent manner and CYP24 splicing pattern could be cell type or tissue specific. The induction of RNA splicing by 1,25(OH)₂D₃ was mainly CYP24 selective. Treatment of cells with parathyroid hormone inhibited basal CYP24 splicing, but failed to inhibit 1,25(OH)₂D₃-induced CYP24 splicing. Further experiments demonstrated that new RNA synthesis was required for the induction of CYP24 splicing by vitamin D. In addition, alteration of multiple signaling pathways also affected CYP24 splicing and cellular sensitivity in response to vitamin D appeared to correlate with the induction of CYP24 splicing. These results suggest that 1,25(OH)₂D₃ not only regulates CYP24 transcription, but also plays an important role in posttranscriptional modulation of CYP24 by inducing its splicing. Our findings reveal an additional regulatory step that makes the vitamin D mediated action more prompt and efficient.

Aberrant crypt foci as predictors of colorectal neoplasia on repeat colonoscopy

OBJECTIVE

To estimate the risk for colorectal neoplasia detected on repeat colonoscopy in relation to aberrant crypt foci (ACF) frequency reported during the previous baseline examination.

METHODS

From July 2003 until December 2008, patients had a colonoscopy with an ACF study using a magnifying colonoscope. The distal 20 cm section of colon was sprayed with Methylene Blue to ascertain the ACF frequency, the independent variable. Patients were categorized into low and high ACF count using the median as the cut point. Data collected from consenting patients included age, gender, height, weight, ethnicity, smoking history, family history of colorectal cancer (CRC), and personal history of colorectal neoplasia. A follow-up colonoscopy was performed at an interval as dictated by clinical surveillance guidelines. The main outcome was surveillance detected advanced colorectal neoplasia (SDAN) detected on repeat colonoscopy. Logistic Regression was used to calculate risk of SDAN on repeat colonoscopy in relation to baseline ACF count.

RESULTS

74 patients had a baseline ACF exam and a repeat surveillance colonoscopy. The median ACF was six and thus a high ACF count was >6 ACF and a low ACF count was ≤6 ACF. Patients diagnosed with SDAN were more likely to have had a high ACF number at baseline compared to patients without these lesions at follow-up (adjusted odds ratio = 12.27; 95% confidence interval: 2.00-75.25) controlling for age, sex, smoking, history of prior adenoma, family history of colon cancer, obesity, and time interval to surveillance exam. A sub analysis of our results demonstrated that this relationship was observed in 48 patients who were undergoing a surveillance colonoscopy for a previous adenoma and not those receiving surveillance for a family history of neoplasia.

CONCLUSIONS

Increased number of ACF in the distal colorectum was independently associated with substantial risk for future advanced neoplasia. This relationship was observed in patients undergoing surveillance for previous adenomas. Thus, ACF may serve as potential biomarkers in patients with adenomas to help identify patients who may need additional surveillance.

Semiparametric estimation for joint modeling of colorectal cancer risk and functional biomarkers measured with errors

This research is motivated by a pilot colorectal adenoma study, where the outcome of interest is the presence of colorectal adenoma representing risk for colorectal cancer, and the predictors of interest are protein biomarkers that are repeatedly measured with errors along the length of a microscopic structure in the human colon, the colon crypt. Biomarkers of this type are referred to as functional biomarkers. The investigators are interested in identifying features of functional biomarkers that are associated with risk for colorectal cancer. In this paper, we investigate a joint modeling approach, where the binary clinical outcome is modeled using a logistic regression model with the unobserved true functional biomarkers as the predictors. Most existing methods are developed either for linear models or for functional biomarkers measured without errors and cannot be directly applied to our data. The applicable methods include a two-step method and a maximum likelihood method, which have some limitations. We propose a robust semiparametric method to overcome the limitations of the existing methods. We study the properties of the proposed method, and show in simulations that it compares favorably with other methods and also offers significant savings in CPU time. We analyze the pilot colorectal adenoma data and show that expression levels of AFC, a tumor suppressor gene, in the transitional area from the proliferation zone to the differentiation zone of colon crypts are likely to be associated with risk for colorectal cancer. Given the relatively small sample size in the pilot study, our results need to be validated in the future full-scale studies.

Dietary acrylamide does not increase colon aberrant crypt foci formation in male F344 rats

Acrylamide, a known rodent and a probable human carcinogen, is spontaneously formed in foods cooked at high temperature. We studied the role of dietary acrylamide in modulating the early stages of colon carcinogenesis and assessed if dietary fat level was critical in altering the effects of acrylamide. Male F344 rats were subcutaneously injected with azoxymethane and were simultaneously randomized into 8 dietary groups (n=8 rats/group). Diets were based on AIN-93G semi-synthetic formula modified to contain either low fat (7% corn oil) or high fat (23.9% corn oil) and acrylamide at 0, 5, 10 or 50 mg/kg diet (wt/wt). All rats received the experimental diets ad libitum for 8 weeks, after which they were killed and their colons assessed for aberrant crypt foci (ACF), putative precancerous lesions. Irrespective of dietary fat level, rats with the highest tested dose of acrylamide (50 mg/kg diet) had significantly lower total ACF (p<0.05) and lower large ACF (those with 4 or more crypts/focus; p<0.001) compared with their respective controls (0 mg/kg diet). A significantly lower number of large ACF (p=0.046) was noted in rats treated with 10 mg/kg diet acrylamide exclusively in the high fat group, compared to the high fat control. This short-term bio-assay to test carcinogenicity of dietary acrylamide in the colon demonstrates that acrylamide, when administered through the diet at doses known to cause rat tumors, does not increase the risk of developing azoxymethane-induced precancerous lesions of the colon in rats. On the contrary, a high dose of dietary acrylamide decreased the growth of precancerous lesions in both low and high fat diet regimens in this model.

The min mouse on FVB background: susceptibility to spontaneous and carcinogen-induced intestinal tumourigenesis

The multiple intestinal neoplasia (Min) mouse is a model for intestinal tumourigenesis. On the C57BL/6J (B6) background, with an incidence of 100%, the Min mouse develops numerous tumours throughout the intestine, particularly in the small intestine. The Min phenotype was backcrossed to the FVB/NJ (FVB) genetic background in order to reduce the number of tumours. Control FVB Min mice had an incidence of 7% tumours, both in the small intestine and in the colon. One or more flat aberrant crypt foci (ACF) were also observed in the colon of 20% of the control mice. Neonatal mice were given one dose of the food-processing contaminant 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) in order to test the chemical induction of tumours and flat ACF. Treatment with PhIP significantly increased both the number and incidence of tumours in the small intestine, and gave a non-significant increase of tumours and flat ACF in the colon.

Effects of adlay bran and its ethanolic extract and residue on preneoplastic lesions of the colon in rats

BACKGROUND

Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is a cereal crop used in traditional Chinese medicine and as a nutritious food. Epidemiologists have suspected that the low cancer rates in southeastern China might be related to adlay. Previous studies have shown that adlay has anti-tumour and anti-inflammatory activity. This study investigated the effect of adlay bran and its fractions on chemically induced colon carcinogenesis in rats.

RESULTS

Adlay bran and its ethanolic extract and residue significantly reduced the number of preneoplastic aberrant crypt foci (ACF) and modified their mucin composition. The inhibitory effect of adlay bran ethanolic extract on ACF showed a dose dependence. Adlay bran and its ethanolic extract suppressed small ACF (one, two or three crypts) and ACF in the distal colon, while the residue suppressed large ACF (four or more crypts).

CONCLUSION

These findings suggest the possibility that adlay bran and its ethanolic extract and residue inhibit colonic preneoplastic lesions in an early stage. Adlay and its fractions may have the potential to be developed as chemopreventive cereal products.

DNA methylation in the rectal mucosa is associated with crypt proliferation and fecal short-chain fatty acids

BACKGROUND

DNA methylation varies throughout the normal colorectal mucosa and DNA methylation in normal appearing mucosa is associated with serrated and adenomatous neoplasia elsewhere within the colorectum.

AIMS

The purpose of this study was to measure luminal chemistry, rectal proliferation and mucosal DNA methylation and thus determine whether regional and pathological patterns of DNA methylation could be explained by luminal and epithelial factors.

METHODS

Twenty healthy subjects had normal rectal mucosal biopsies and a 24-h fecal collection. Rectal biopsies were analyzed for epithelial proliferation (Ki67 immunohistochemistry) and DNA methylation at 17 different markers, including "type A" markers (ESR1, GATA5, HIC1, HPP1, SFRP1), "type C" markers (MGMT, MLH1, CDKN2A, MINT1, MINT2, MINT31, IGF2, CACNA1G, NEUROG1, SOCS1, RUNX3), and LINE-1. Fecal analysis included short-chain fatty acids (SCFA), pH and ammonia. Mean "type A" and CIMP panel methylation Z-scores were calculated.

RESULTS

Rectal proliferation was significantly correlated with methylation at ESR1 (ρ = 0.81, P = 0.003) and GATA5 (ρ = 0.78, P = 0.012). LINE-1 methylation was 71.7 vs. 74.1%, in patients with "low" and "high" fecal total SCFA concentration (defined by the median value), respectively (P = 0.0019). On multivariate linear regression "type A" methylation was independently associated with rectal proliferation (P = 0.001). LINE-1 methylation was directly associated with rectal proliferation (P = 0.038) and total fecal SCFA concentration (P = 0.002), and inversely associated with fecal NH(3) concentrations (P = 0.003).

CONCLUSIONS

DNA methylation in normal rectal mucosa is associated with crypt proliferation and fecal SCFA concentration. These associations may help to explain regional differences in DNA methylation as well as providing a possible link between the colorectal lumen and carcinogenesis.

Cancer chemopreventive potential of the Egyptian flaxseed oil in a rat colon carcinogenesis bioassay--implications for its mechanism of action

The possible chemopreventive effects of natural Egyptian flaxseed oil on preneoplasia and cancer formation were investigated in a rat medium-term colon carcinogenesis bioassay. Male Wistar rats were divided into 6 groups. Groups 1, 3 and 5 were initiated by 1,2-dimethylhydrazine (DMH) 20 mg/kg body weight s.c. 8 times, twice a week to initiate colon carcinogenesis. Groups 1 and 3 received 20% or 5% flaxseed oil respectively in diet in post initiation stage until the end. Groups 2 and 4 served as a flaxseed dose corresponding controls without carcinogen initiation, while rats in group 6 served as negative controls. Distribution and total numbers of aberrant crypt foci (ACF), putative preneoplastic lesions, particularly those with ≥4 aberrant crypts (ACs), and the numbers and sizes of colon tumors (adenoma and carcinoma) were significantly decreased by both treatment doses of flaxseeds as compared to group 5. Histochemical investigation revealed that the numbers of mucus-secreting cells in the colonic mucosa were reduced gradually during progression of colon carcinogenesis. Intriguingly, flaxseed oil caused the numbers and integrity of the mucus-secreting cells to retain close to normal levels and in a dose dependent manner. Moreover, the hematological parameters were almost constant between the groups particularly at the dose of 5% as compared to groups 5 and 6. PCNA-labeled indexes (PCNA-LI) in the DMH-initiated colonic mucosa were found to be decreased by both doses of flaxseeds administration. In conclusion, the present study showed that the post initiation dietary administration of flaxseeds oil suppressed DMH-induced colon carcinogenesis in rats without significant side effects. The mechanism is likely to be through its inhibitory effects on early cellular proliferation and modulation of mucin secretion properties in the initiated colonic mucosa.

Stem cells and inflammation in the intestine

Knowledge of stem cell biology in the intestine is increasing exponentially and it is one of the current hot topics 'of the day'. Yet it is only recently that molecules such as Lgr5 and Bmi1 have been shown to reliably mark stem cells and have revealed the stem cell location throughout the murine gastrointestinal tract. However, there is a scarcity of meaningful work within their human counterpart. Nevertheless, recent studies have demonstrated the processes of niche succession, where one stem cell takes over the entire population of stem cells within a crypt; and monoclonal conversion, whereby the entire crypt becomes a clonal population of cells, are present in the human crypt. This work has also shown how crypts themselves divide and expand in the human colon.

Histomorphology of aberrant crypt foci in colorectal carcinoma

Colorectal carcinogenesis is a complex multistep process that includes changes in histomorphological appearance of the colonic mucosa and changes at molecular level. Aberrant crypt foci (ACF) was first described by Bird in 1987 on examination of methylene-blue-stained colonic mucosa of azoxymethane-treated mice under light microscopy. Since then ACF was considered as the earliest preneoplastic change that can be seen in the colonic mucosa. The aim of this study was to look at the histomorphology and distribution of ACF in colorectal carcinoma. 50 formalin-fixed archival colectomy specimens for colorectal carcinoma were examined under light microscopy after staining with 0.2% methylene blue. ACF was identified by larger and darker crypts with thickened epithelium, and often elevated from adjacent normal mucosa. ACF was found in 41 of 50 colectomy specimens examined. There were 328 ACF consisting of 36 (11.0%) ACF without hyperplasia or dysplasia, 263 (80.2%) ACF with hyperplasia and 29 (8.8%) ACF with dysplasia. Of these 29 ACF with dysplasia, 25 showed low grade dysplasia and four high grade dysplasia. The density of ACF was higher in the left colon, those older than 65 years of age and among males but these findings were statistically not significant. The crypt multiplicity of hyperplastic ACF (30.149, SD 28.395) was larger than dysplastic ACF (20.613, SD 40.128). The spectrum of histological changes observed probably represent the evolution of ACF in colorectal carcinogenesis.

Toll-like receptor 2 signaling protects mice from tumor development in a mouse model of colitis-induced cancer

Inflammatory bowel disease (IBD) is a disorder of chronic inflammation with increased susceptibility to colorectal cancer. The etiology of IBD is unclear but thought to result from a dysregulated adaptive and innate immune response to microbial products in a genetically susceptible host. Toll-like receptor (TLR) signaling induced by intestinal commensal bacteria plays a crucial role in maintaining intestinal homeostasis, innate immunity and the enhancement of intestinal epithelial cell (IEC) integrity. However, the role of TLR2 in the development of colorectal cancer has not been studied. We utilized the AOM-DSS model for colitis-associated colorectal cancer (CAC) in wild type (WT) and TLR2(-/-) mice. Colons harvested from WT and TLR2(-/-) mice were used for histopathology, immunohistochemistry, immunofluorescence and cytokine analysis. Mice deficient in TLR2 developed significantly more and larger colorectal tumors than their WT controls. We provide evidence that colonic epithelium of TLR2(-/-) mice have altered immune responses and dysregulated proliferation under steady-state conditions and during colitis, which lead to inflammatory growth signals and predisposition to accelerated neoplastic growth. At the earliest time-points assessed, TLR2(-/-) colons exhibited a significant increase in aberrant crypt foci (ACF), resulting in tumors that developed earlier and grew larger. In addition, the intestinal microenvironment revealed significantly higher levels of IL-6 and IL-17A concomitant with increased phospho-STAT3 within ACF. These observations indicate that in colitis, TLR2 plays a protective role against the development of CAC.

Variational image segmentation for endoscopic human colonic aberrant crypt foci

The aim of this paper is to introduce a variational image segmentation method for assessing the aberrant crypt foci (ACF) in the human colon captured in vivo by endoscopy. ACF are thought to be precursors for colorectal cancer, and therefore their early detection may play an important clinical role. We enhance the active contours without edges model of Chan and Vese to account for the ACF's particular structure. We employ level sets to represent the segmentation boundaries and discretize in space by finite elements and in (artificial) time by finite differences. The approach is able to identify the ACF, their boundaries, and some of the internal crypts' orifices.