Epidemiology of colonic aberrant crypt foci: review and analysis of existing studies

Human Intestinal Defensin 5 Ameliorates the Sensitization of Colonic Cancer Cells to 5-Fluorouracil

BACKGROUND AND AIM

The increasing dilemma of multidrug-resistant cancer cells in response to currently available chemotherapeutic drugs and their associated side effect(s), calls for the investigation of alternative anticancer advances and molecules. Therefore, the present study aimed to elucidate the combinatorial potential against colon cancer of human defensin 5 in combination with 5-fluorouracil (5-FU), and against 5-FU resistant colon tumor cells.

METHODS

The in vivo combinatorial potential of HD-5 with 5-FU was elucidated in terms of tumor morphometrics, apoptosis assay, surface morphology histology of the colon(s), and transcriptional alterations. Changes in membrane dynamics with mucin expression were evaluated by fluorescence microscopy and histochemistry. The in vitro activity of the peptide/drug conjunction was explored by phase contrast microscopy, MTT, LDH assay, and AO/EtBr staining. Chemoresistance to 5-FU was determined by phase contrast microscopy, MTT assay, annexin V-FITC/PI flow cytometry, and MDR-1, Bak, and Bax expression.

RESULTS

In vivo decreases in tumor parameters, with a marked increase in apoptosis and neutrophil infiltrations indicated restoration of normal architecture with improved mucin content in the treated colons. This happened with substantial changes in key molecular markers of the intrinsic apoptotic cascade. Membrane dynamics revealed that peptides and chemotherapeutic drugs could bind to cancerous cells by taking advantage of altered levels of membrane fluidity.

CONCLUSION

Peptide treatment of drug-resistant Caco-2 cells promotes enhanced 5-FU uptake, in contrast to when cells were treated with 5-FU alone. Hence, HD-5 as an adjunct to 5-FU, exhibited strong cancer cell killing even against 5-FU-resistant tumorigenic cells.

The Effect of Low Doses of Acetylsalicylic Acid on the Occurrence of Rectal Aberrant Crypt Foci

Background and Objectives: Aberrant crypt foci (ACF) are one of the earliest putative preneoplastic and, in some cases, neoplastic lesions in human colons. Many studies have confirmed the reduction of ACFs and colorectal adenomas after treatment with acetylsalicylic acid (ASA) commonly referred to as ASA; however, the minimum effective dose of ASA and the duration of use has not been fully elucidated. The objective of our study was to assess the significance of low dose ASA (75-mg internally once daily) to study the chemopreventive effect of ASA in ACF and adenomas development in patients taking this drug for a minimum period of 10 years. Materials and Methods: Colonoscopy, combined with rectal mucosa staining with 0.25% methylene blue, was performed on 131 patients. The number of rectal ACF in the colon was divided into three groups: ACF < 5; ACF 5−10; and ACF > 10. Patients were divided into two groups: the “With ASA” group (the study group subjects taking ASA 75-mg daily for 10 years); and “Without ASA” group (control group subjects not taking ASA chronically). The incidence of different types of rectal ACF and colorectal polyps in both groups of subjects was analysed and ascertained. Results: Normal ACF was found in 12.3% in the study group vs. 87.7% control group, hyperplastic 22.4% vs. 77.6%, dysplastic 25% vs. 75%, mixed 0% vs. 100%. Treatment with ASA affects the occurrence of colorectal adenomas. The amount of dysplastic ACFs was lower in the study group than in the control group. The increase in dysplastic ACFs decreases with age in both groups, with the increase greater in those not taking ASA. Conclusions: Patients who take persistent, chronic (>10 years) low doses of ASA have a lower total number of all types of rectal ACFs and adenomas compared to the control group.

Anticancer potential of human intestinal defensin 5 against 1, 2-dimethylhydrazine dihydrochloride induced colon cancer: A therapeutic approach

The escalating predicament of multidrug resistant cancer cells and associated side effects of conventional chemotherapy necessitates the exploration of alternative anticancer therapies. The present study evaluated anticancer therapeutic potential of human defensin 5 (HD-5) against colon cancer. The in vivo anticancer efficacy of HD-5 against 1,2-dimethylhydrazine (DMH) induced colon cancer was elucidated in terms of tumor biostatistics, number of aberrant crypt foci (ACF), in situ apoptosis assay,changes in morphological as well as histological architecture of colon(s). The direct interaction of peptide was investigated by incubating peptide with normal and/or cancerous colonocytes followed by phase contrast, Hoechst 3342 and AO/PI staining as well as confocal microscopy. Changes in membrane dynamics were evaluated by MC 540 and N-NBD-PE staining. In vivo decrease(s) in tumor parameters, number of aberrant crypt foci along with marked increase in the rate of apoptosis was observed.H&E staining revealed neutrophils infiltration and restoration of normal architecture in treated colon(s) which was consistent with scanning electron microscopic observations. Furthermore, non-membranolytic mechanism was found to be acquired by peptide as it could traverse cell membrane gaining access to nucleus and cytoplasm thereby disintegrating cellular architecture. MC 540 and NBD-PE staining revealed that peptide could bind to cancerous cells by taking advantage of altered fluidity levels. Our results indicated that HD-5 exhibited strong cancer cell killing and does not affect normal host cells. The peptide can be exploited as promising option to combat developing menace of colon cancer and/or can at least be used as an adjunct to present day chemotherapies.

Ganoderma lucidum Polysaccharide Enzymatic Hydrolysate Suppresses the Growth of Human Colon Cancer Cells via Inducing Apoptosis

Ganoderma lucidum is a popular traditional Chinese medicine used in China to improve health. Previous researches have revealed that the polysaccharide from G. lucidum could exert diversity activities, including immunomodulation, antioxidant, and antitumor effects. However, the effect of enzymatically hydrolyzed G. lucidum polysaccharide (EGLP) in colorectal cancer (CRC) progression remains unknown. The present research aimed to investigate the antitumor mechanism of EGLP in human colon cancer cells. For this purpose, the cytotoxic effects of EGLP were measured by the (3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) method. The apoptosis was evoked upon EGLP treatment, which was assayed using flow cytometry. The results indicated that EGLP may induce apoptosis in human colon cancer cell (HCT-116) cells via the upregulation of BCL-2 associated X protein (Bax), phospho-extracellular regulated protein kinases (P-ERK), and cleaved caspase-3 expression and downregulation of B-cell lymphoma-2 (Bcl-2), phospho-serine/threonine kinase 1 (p-Akt1), and cyclo-oxygen-ase (COX-2) expression. The obtained findings indicated EGLP as a new therapeutic agent in fighting CRC.

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.

Occurrence of colorectal aberrant crypt foci depending on age and dietary patterns of patients

Background

Aberrant crypt foci (ACF) are commonly considered the early pre-cancerous lesions that can progress to colorectal cancer (CRC). The available literature data reveal that age, dietary factors and lifestyle can affect the development of several dozen percentages of malignant tumours, including CRC. In the present study, an attempt was made to assess the incidence and growth dynamics of ACF and to determine whether the type of diet affected the development and number of AFC.

Methods

Colonoscopy combined with rectal mucosa staining with 0.25% methylene blue was performed in 131 patients. On the day of examination, each patient completed a questionnaire regarding epidemiological data. According to their numbers, colorectal ACF were divided into three groups. The findings were analysed statistically. The Student’s t test and the U test were applied in order to determine the significance of differences of means and frequency of events in both groups. Statistica 7.1 and Excel 2010 were used.

Results

The single ACF occur in the youngest individuals (ACF < 5). Since the age of 38 years, the number of ACF gradually increases to show a decreasing tendency since the age of 60 years. The number of 5 < ACF < 10 occurs slightly later, since the age of 50 years, and dynamically increases reaching the maximum at the age of 62 years, subsequently the increase is proportional. ACF > 10 occur at a more advanced age (55 years) and their number gradually increases with age. The maximum number is observed at the age of 77 years.

In individuals not using high-fibre diets and with high intake of red meat, the probability of higher numbers of ACF increases. The probability of higher numbers of ACF (5 < ACF10) was observed in patients with colon diverticula. In patients with higher BMI, the number of ACF is higher.

Conclusion

Age significantly affects the number of colorectal ACF. The types of foods consumed can considerably increase the risk of colorectal ACF, which is particularly visible in individuals who do not regularly use high-fibre diets, those obese and with colon diverticula.

Distinct Transcriptional Changes and Epithelial-Stromal Interactions Are Altered in Early-Stage Colon Cancer Development

Although the progression of mutated colonic cells is dependent upon interactions between the initiated epithelium and surrounding stroma, the nature of these interactions is poorly understood. Here, the development of an ultrasensitive laser capture microdissection (LCM)/RNA-seq approach for studying the epithelial and stromal compartments of aberrant crypt foci (ACF) is described. ACF are the earliest identifiable preneoplastic lesion found within the human colon and are detected using high-definition endoscopy with contrast dye spray. The current analysis focused on the epithelium of ACF with somatic mutations to either KRAS, BRAF, or APC, and expression patterns compared with normal mucosa from each patient. By comparing gene expression patterns among groups, an increase in a number of proinflammatory NF-κB target genes was identified that was specific to ACF epithelium, including TIMP1, RELA, and RELB Distinct transcriptional changes associated with each somatic mutation were observed and a subset of ACF display BRAF(V600E)-mediated senescence-associated transcriptome characterized by increased expression of CDKN2A Finally, LCM-captured ACF-associated stroma was found to be transcriptionally distinct from normal-appearing stroma, with an upregulation of genes related to immune cell infiltration and fibroblast activation. Immunofluorescence confirmed increased CD3(+) T cells within the stromal microenvironment of ACF and an abundance of activated fibroblasts. Collectively, these results provide new insight into the cellular interplay that occurs at the earliest stages of colonic neoplasia, highlighting the important role of NF-κB, activated stromal fibroblasts, and lymphocyte infiltration.

IMPLICATIONS

Fibroblasts and immune cells in the stromal microenvironment play an important role during the earliest stages of colon carcinogenesis. Mol Cancer Res; 14(9); 795-804. ©2016 AACR.

Effects of Walnut Consumption on Colon Carcinogenesis and Microbial Community Structure

Walnuts are composed of a complex array of biologically active constituents with individual cancer-protective properties. Here, we assessed the potential benefit of whole walnut consumption in a mouse tumor bioassay using azoxymethane. In study 1, a modest reduction (1.3-fold) in tumor numbers was observed in mice fed a standard diet (AIN-76A) containing 9.4% walnuts (15% of total fat). In study 2, the effects of walnut supplementation was tested in the Total Western Diet (TWD). There was a significant reduction (2.3-fold; P < 0.02) in tumor numbers in male mice fed TWD containing 7% walnuts (10.5% of total fat). Higher concentrations of walnuts lacked inhibitory effects, particularly in female mice, indicating there may be optimal levels of dietary walnut intake for cancer prevention. Since components of the Mediterranean diet have been shown to affect the gut microbiome, the effects of walnuts were therefore tested in fecal samples using 16S rRNA gene sequencing. Carcinogen treatment reduced the diversity and richness of the gut microbiome, especially in male mice, which exhibited lower variability and greater sensitivity to environmental changes. Analysis of individual operational taxonomic units (OTU) identified specific groups of bacteria associated with carcinogen exposure, walnut consumption, and/or both variables. Correlation analysis also identified specific OTU clades that were strongly associated with the presence and number of tumors. Taken together, our results indicate that walnuts afford partial protection to the colon against a potent carcinogenic insult, and this may be due, in part, to walnut-induced changes to the gut microbiome. Cancer Prev Res; 9(8); 692-703. ©2016 AACR.

Serrated pathway: alternative route to colorectal cancer

Serrated polyps have been an area of intense focus for gastroenterologists over the past several years. Contrary to what was thought before, a growing body of literature indicates that these polyps can be precursors of colorectal cancer (CRC). Most of these lesions, particularly those in the proximal colon, have so far been under-recognized and missed during colonoscopy, qualifying these lesions to be the main cause of interval cancers. It is estimated that 10%-20% of CRCs evolve through this alternative, serrated pathway, with a distinct genetic and epigenetic profile. Aberrant DNA methylation plays a central role in the development of this CRC subtype. This characteristic molecular background is reflected in a unique pathological and clinical manifestation different from cancers arising via the traditional pathway. In this review we would like to highlight morphological, molecular and clinical features of this emerging pathway that are essential for gastroenterologists and may influence their everyday practice.

Relationship of human rectal aberrant crypt foci and formation of colorectal polyp: One-year following up after polypectomy

AIM: To clarify the relationship of human rectal aberrant crypt foci and formation of colorectal polyp.

METHODS: Eighty-nine subjects were recruited from the population of Japanese individuals who underwent polypectomy at Yokohama City University Hospital. All patients had baseline adenomas removed at year 0 colonoscopy. Aberrant crypt foci (ACF) were defined as lesions in which the crypts were more darkly stained with methylene blue than normal crypts and had larger diameters, often with oval or slit-like lumens and a thicker epithelial lining.

RESULTS: A total of 366 ACFs were identified in 89 patients; all had baseline adenomas removed at the first examination (year 0) colonoscopy and returned for the second (year 1). ACF in the lower rectum were assessed at year 0 and study group were divided into two groups depend on ACF numbers, 0-3 or over 3. All participants were examined in the number and maximum size of adenoma. There was no statistical difference in number and maximum size of ACF at year 0, however, maximum size of adenoma was larger in over 3 group than 0-3 group at year 1.

CONCLUSION: The number of ACF may be a predictive factor of relatively large adenoma incidence in the pilot phase study.

Number of aberrant crypt foci in the rectum is a useful surrogate marker of colorectal adenoma recurrence

AIM

Endoscopic screening and removal of colorectal adenomas can reduce the incidence of colorectal cancer. However, given the possibility of adenoma recurrence, surveillance colonoscopy is currently recommended after the initial screening and removal of colorectal adenomas. Aberrant crypt foci (ACF) have been shown to serve as a reliable surrogate marker of colorectal carcinogenesis. In this study, the relationship between the number of ACF at the initial endoscopic polypectomy and the likelihood of colorectal adenoma recurrence after polypectomy were investigated.

METHODS

High-magnification chromoscopic colonoscopy was performed in 82 subjects who underwent endoscopic polypectomy to identify ACF in the lower rectum. Surveillance colonoscopy was then performed 3 years after the baseline polypectomy at Yokohama City University Hospital.

RESULTS

The number of ACF was greater in patients who showed adenoma recurrence (7.88 ± 6.35) than in those who did not (2.19 ± 2.95) (P < 0.001). Receiver-operating curve analysis showed that the number of ACF was a highly specific predictor of the risk of adenoma recurrence.

CONCLUSIONS

This is the first study conducted to investigate the relationship between the number of ACF after endoscopic polypectomy and the likelihood of recurrence of colorectal adenomas. These results suggest that the number of ACF is a useful predictor of the likelihood of colorectal adenoma recurrence.

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.

Sodium butyrate does not decrease the evolution of precancerous lesions in rats

PURPOSE

To evaluate the preventive effect of sodium butyrate in the appearance of aberrant crypt foci (ACF) in rats after induction with the carcinogen 1,2-dimethylhydrazine (DMH).

METHODS

Forty Wistar rats were separated into four groups (n=10) distributed as follows: control 1, control 2, butyrate 1 and butyrate 2. The groups control 1 and butyrate 1 remained under experimentation for 4 weeks, while the groups control 2 and butyrate 2 remained for 8 weeks. In the first four weeks, the animals of the control groups received water ad libitum and the animals of the butyrate groups received a sodium butyrate solution (3.4%) ad libitum. Injections of the drug 1,2-dimethylhydrazine were applied during the two first weeks of the experiment in all the animals, concurrently with the application of sodium butyrate. The large intestine of the animals was removed, for the analysis of the ACF and of the content of polyamines. The animal feces were collected for the analysis of the SCFA profile.

RESULTS

The spermidine presented a higher concentration in the group butyrate 2 in comparison to the group control 2. There was a significant difference in the concentration value (µmol/mL) of acetate in comparison to the groups control 2 and butyrate 2.

CONCLUSION

The use of sodium butyrate together with the induction of colorectal cancer was not effective in the prevention of the disease progression.

Chemopreventive potential of synergy1 and soybean in reducing azoxymethane-induced aberrant crypt foci in fisher 344 male rats

Synergy1, a prebiotic composed of Inulin and Oligofructose (1 : 1). Soybean meal is a natural source of isoflavones. The objective was to investigate the effects of feeding Synergy1 and SM on the incidence of azoxymethane- (AOM-) induced aberrant crypt foci (ACF) in Fisher 344 male rats. Rats (54) were randomly assigned to 9 groups (n = 6). Control group (C) was fed AIN-93G and treatment groups Syn1 and SM at 5% and 10% singly and in combinations. Rats were injected with two s/c injections of AOM at 7 and 8 weeks of age at 16 mg/kg body weight and killed at 17 weeks by CO₂ asphyxiation. Colonic ACF enumeration and hepatic enzyme activities were measured. Reductions (%) in total ACF among treatment groups fed combinations were higher (67–77) compared to groups fed singly (52–64). Synergistic mechanisms among phytochemicals may be responsible suggesting protective role in colon carcinogenesis with implications in food product development.

Randomized phase II trial of sulindac, atorvastatin, and prebiotic dietary fiber for colorectal cancer chemoprevention

Sulindac, atorvastatin, or prebiotic dietary fiber may reduce colorectal cancer (CRC) risk. However, clinical trial data are currently limited. We conducted a randomized, phase II chemoprevention trial involving subjects 40 years or older, with previously resected colon cancer or multiple/advanced colorectal adenomas. Magnification chromoendoscopy (MCE) was performed to identify and characterize rectal aberrant crypt foci (ACF); eligibility criteria required five or more rectal ACFs at baseline. Intervention assignments were as follows: (a) atorvastatin 20 mg qd; (b) sulindac 150 mg bid; (c) oligofructose-enriched inulin (as ORAFTI®Synergy1) 6 gm bid; or (d) control (maltodextrin) 6 gm bid, for 6 months. Percent change in rectal ACF number (%ΔACF) within arm was the primary endpoint. Secondary endpoints included changes in proliferation (Ki67) and apoptosis (caspase-3), as measured from normal mucosa biopsy samples. Among 85 eligible randomized subjects, 76 (86%) completed the trial per protocol. The median (range) of rectal ACF was 9 (5-34) and 8 (0-37) at baseline and postintervention, respectively. The median (SD) for %ΔACF was 5.6 (-69% to 143%), -18.6 (-83% to 160%), -3.6 (-88% to 83%), and -10.0 (-100% to 117%) in the atorvastatin, sulindac, ORAFTI®Synergy1 and control arms, respectively. Neither within-arm (P = 0.12-0.59) nor between-arm (P = 0.30-0.92) comparisons of %ΔACF were statistically significant. The active and control interventions also seemed to have similar effects on mucosal proliferation and apoptosis (P > 0.05 for each comparison). Data from this multicenter, phase II trial do not provide convincing evidence of CRC risk reduction from 6-month interventions with atorvastatin, sulindac, or ORAFTI®Synergy1, although statistical power was limited by the relatively small sample size.

Chlorogenic acid differentially alters hepatic and small intestinal thiol redox status without protecting against azoxymethane-induced colon carcinogenesis in mice

Colorectal cancer (CRC) is a leading cause of cancer-related deaths in the United States. Epidemiological data have suggested that coffee consumption is inversely related to CRC risk, which may be attributed to chlorogenic acid (CGA), an ester of caffeic acid (CA) and quinic acid. This study was conducted to determine whether chronic dietary CGA supplementation would attenuate tumorigenesis and oxidative stress in a mouse model of azoxymethane (AOM)-induced colon cancer. Mice (4-wk old; n = 15/group) were fed CGA (0%, 0.01%, or 0.1%) for 20 wk and received 6 weekly intraperitoneal AOM injections (10 mg/kg). CGA and CA dose-dependently accumulated in the small intestinal mucosa. AOM induced (P < 0.05) colonic aberrant crypt foci (14.2 +/- 1.9/field) and tumors (14.6 +/- 1.1/colon), which were correlated (r = .677; P < 0.05), and CGA at either dose did not reduce tumorigenesis. Hepatic GSH/GSSG and Cys/CySS ratios were unaffected by AOM, but CGA at 0.1% increased these ratios by decreasing GSSG and CySS. CGA did not affect the ratios of small intestinal GSH/GSSG or Cys/CySS, which were decreased in response to AOM treatment. Collectively, these data indicated that CGA did not protect against AOM-induced tumorigenesis but affected hepatic thiol redox status in this colon cancer model.

Beta-catenin expression is altered in dysplastic and nondysplastic aberrant crypt foci of human colon

PURPOSE

Aberrant crypt foci (ACF) of the colon are possible precursors of adenoma and cancer. beta-catenin alterations are early events in human colorectal carcinogenesis. beta-catenin expression is altered in colorectal cancer, adenoma, and ACF with dysplasia. Here, we describe the expression of beta-catenin in ACF, especially nondysplastic ACF.

METHODS

Rectal chromoscopy with 4% indigo carmine was performed on 418 subjects and 146 biopsy specimens, including 10 dysplastic ACF, 106 nondysplastic ACF, and 30 normal colonic mucosal controls taken under endoscopy. The expression and subcellular distribution of beta-catenin were assessed by immunohistochemistry.

RESULTS

beta-catenin expression was altered in 1 of 30 (3.3%) normal mucosa, 30 of 106 (28.3%) nondysplastic ACF, and 10 of 10 (100%) dysplastic ACF (P<0.001). Notably, most cells with altered beta-catenin expression in nondysplastic ACF were limited to the bottom of the crypt, where stem cells are located.

CONCLUSIONS

Both dysplastic and nondysplastic ACF have altered beta-catenin expression and play a role in colon tumorigenesis.

PUMA suppresses intestinal tumorigenesis in mice

Defective apoptosis contributes to tumorigenesis, although the critical molecular targets remain to be fully characterized. PUMA, a BH3-only protein essential for p53-dependent apoptosis, has been shown to suppress lymphomagenesis. In this study, we investigated the role of PUMA in intestinal tumorigenesis using two animal models. In the azoxymethane (AOM)/dextran sulfate sodium salt model, PUMA deficiency increased the multiplicity and size of colon tumors but reduced the frequency of beta-catenin hotspot mutations. The absence of PUMA led to a significantly elevated incidence of precursor lesions induced by AOM. AOM was found to induce p53-dependent PUMA expression and PUMA-dependent apoptosis in the colonic crypts and stem cell compartment. Furthermore, PUMA deficiency significantly enhanced the formation of spontaneous macroadenomas and microadenomas in the distal small intestine and colon of APC(Min/+) mice. These results show an essential role of PUMA-mediated apoptosis in suppressing intestinal tumorigenesis in mice.

Screening for in vitro and in vivo antitumor activities of the mushroom Agaricus blazei

We have investigated the in vitro antitumor activity of the mushroom Agaricus blazei Murill on human cancer cell lines as well as its potential anticancer activity in a model of rat colon carcinogenesis. The in vitro anticancer analysis was performed using 9 human cancer cell lines incubated with organic and aqueous extracts of A. blazei. Antitumor activity was observed with the dichloromethane/methanol and hexanic extracts of A. blazei at 250 mu g/ml for all cancer cell lines tested. No antiproliferative/cytotoxic activities were detected for the aqueous, methanol, ethyl acetate, or n-butanolic extracts. In the in vivo analysis, crude A. blazei was given orally after carcinogen treatment in a rat medium-term study (20 weeks) of colon carcinogenesis using aberrant crypt foci (ACF) as biomarker. Male Wistar rats were given dimethylhydrazine (DMH) and then were fed A. blazei at 5% in the diet until Week 20. ACF were scored for number and crypt multiplicity. A. blazei intake did not suppress ACF development or crypt multiplicity induced by DMH. No differences in tumor incidence in the colon were observed among the DMH-treated groups. Our results indicate that employing A. blazei in the diet does not have a suppressive effect on colon carcinogenesis.

Number of aberrant crypt foci associated with adiposity and IGF1 bioavailability

BACKGROUND

Dysregulation of the insulin-like growth factor (IGF) system, a common consequence of adiposity-induced insulin resistance, may be a key underlying mechanism linking excess body weight with colon cancer. Evidence has been derived from studies of cancer and polyps. Supporting data about aberrant crypt foci (ACF), putative pre-polyp changes, have been generated only from animal studies to date.

METHODS

We randomly selected 26 patients with sex-specific elevated waist-hip-ratio (WHR) and 26 with normal values from a series of 150 patients seeking routine colonoscopy at the University of Connecticut Health Center. Cross-sectional analyses were performed of ACF number (<5, > or = 5) in relation to total IGF1, IGF-binding protein-3 (IGFBP3), insulin, body mass index (BMI), WHR and waist circumference (WC). Visualized ACF in the 20 cm of the distal colon were counted using advanced endoscopic imaging.

RESULTS

Patients with > or = 5 ACF had higher BMI, WHR, and WC compared with patients with >5 ACF (p = 0.04, p = 0.03, and p = 0.01, respectively). IGFBP3 was reduced (p = 0.02) and IGF1:IGFBP3 molar ratio was greater (p = 0.03) in patients with > or = 5 ACF. We did not observe significant associations between ACF number and insulin or total IGF1.

CONCLUSIONS

Our study provides the first report in humans of a possible association of ACF prevalence and IGF1 bioavailability as characterized by IGF1:IGFBP3 molar ratio and IGFBP3 level. More research is needed to determine whether this relationship is varied by ACF features (e.g., size, dysplasia, molecular changes), synchronous cancer and polyps, and is modified by colon cancer risk factors.

Azoxymethane-induced rat aberrant crypt foci: Relevance in studying chemoprevention of colon cancer

The pathogenesis of colon cancer involves sequential and multistep progression of epithelial cells initiated to a cancerous state with defined precancerous intermediaries. Aberrant crypt foci (ACF) represent the earliest identifiable intermediate precancerous lesions during colon carcinogenesis in both laboratory animals and humans. ACF are easily induced by colon-specific carcinogens in rodents and can be used to learn more about the process of colon carcinogenesis. For over two decades, since its first discovery, azoxymethane (AOM)-induced rodent ACF have served as surrogate biomarkers in the screening of various anticarcinogens and carcinogens. Several dietary constituents and phytochemicals have been tested for their colon cancer chemopreventive efficacy using the ACF system. There has been substantial effort in defining and refining ACF in terms of understanding their molecular make-up, and extensive research in this field is currently in progress. In chemoprevention studies, AOM-induced rat ACF have been very successful as biomarkers, and have provided several standardized analyses of data. There have been several studies that have reported that ACF data do not correlate to actual colon tumor outcome, however, and hence there has been an ambiguity about their role as biomarkers. The scope of this mini-review is to provide valuable insights and limitations of AOM-induced rat ACF as biomarkers in colon cancer chemoprevention studies. The role of the dynamics and biological heterogeneity of ACF is critical in understanding them as biomarkers in chemoprevention studies.

Lack of chemopreventive activity of Agaricus blazei mushroom on the development of 1,2-dimethylhydrazine-induced colonic aberrant crypt foci in rats

Chemopreventive and immunomodulatory potential of methanolic (MET) and dichloromethanic (DCl) extracts of Agaricus blazei mushroom were investigated in the postinitiation stage of colon carcinogenesis in male Wistar rats. Animals were initiated with 1,2-dimethylhydrazine (DMH) and treated i.g. with DCl or MET extracts. After 9 wk, animals were sacrificed for evaluation of aberrant crypt foci (ACF) development, crypt cellular proliferation, preneoplastic liver lesions (GST-P), proliferative response of spleen cells to mitogen, and natural killer activity. Administration of DCl extracts did not suppress DMH-induced colonic ACF nor did it affect the crypt multiplicity, but the highest dose of MET significantly reduced the development of preneoplastic lesions in the colon and liver. Lymphoproliferative response was slightly decreased in the initiated control group, which was restored by treatment with MET. No toxicity from DCl and MET extracts was observed (groups MET and DCl).

Lack of chemoprevention of dietary Agaricus blazei against rat colonic aberrant crypt foci

The mushroom Agaricus blazei (Ab) has been widely used in folk medicine to treat various diseases including cancer. No information is available on its possible protective effects on the development of colon cancer. The potential blocking effect of Ab intake on the initiation stage of colon carcinogenesis was investigated in a short-term (4-week) bioassay using aberrant crypt foci (ACF) as biomarker. Male Wistar rats were given four subcutaneous injections of the carcinogen 1,2-dimethylhydrazine (DMH, 40 mg/kg bw, twice a week), during 2 weeks to induce ACF. The diet containing Ab at 5% was given 2 weeks before and during carcinogen treatment to investigate the potential beneficial effects of this edible mushroom on DMH-induced ACF. All groups were killed at the end of the fourth week. The colons were analyzed for ACF formation in 1% methylene blue whole-mount preparations and for cell proliferation in histological sections immunohistochemically stained for the proliferating cell nuclear antigen (PCNA). All DMH-treated rats developed ACF mainly in the middle and distal colon. Agaricus blazei intake at 5% did not alter the number of ACF induced by DMH or the PCNA indices in the colonic mucosa. Thus, the results of the present study did not confirm a chemopreventive activity of Ab on the initiation stage of rat colon carcinogenesis.

Aberrant crypt focus size predicts distal polyp histopathology

Aberrant crypt foci (ACF) are the earliest histopathologic lesion associated with colorectal cancer. ACFs are commonly used as a surrogate marker for colorectal cancer chemoprevention studies in rodents and, more recently, in humans. However, ACF prevalence in unselected populations is not known, nor which ACF features are important for predicting polyp histopathology. To address these questions, we did magnification chromo-colonoscopy on all patients undergoing routine colorectal cancer screening over a 31-month period. ACFs were classified by location, size (small, <20 crypts/ACF; medium, 20-100 crypts/ACF; large, >100 crypts/ACF), and whether they were elevated above the tissue plane. Overall, 802 magnification chromo-colonoscopies with ACF enumeration were done. Mean patient age was 58.6 +/- 8.5 years, of whom 56% were female, 58% were African American, 21% were Caucasian, and 16% were Latino. Total ACF number, along with increasing ACF size and elevation, correlated with the presence of distal hyperplastic polyps and were higher in African Americans. In contrast, ever-smaller ACFs correlated with the presence of distal adenomas and were independent of age and race. The odds ratio for patients with >or=6 small ACFs and adenomas was 6.02 (95% confidence interval, 2.64-13.70) compared with patients with <or=5 small ACFs, whereas the odds ratio for patients with >or=1 large ACF and hyperplastic polyps was 5.88 (95% confidence interval, 3.00-11.67) compared with patients with none. Small flat ACFs correlate with the presence of distal adenomas, whereas large raised ACFs correlate with the presence of hyperplastic polyps.

Effects of resistant starch on colonic preneoplastic aberrant crypt foci in rats

This study was designed to determine the effects of resistant starch (RS) at different levels on the azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) at the pre-initiation (PI) and promotion (P) stages in Wistar rats. According to the consuming assigned diets, all animals received AOM at a dosage of 15 mg/kg once a week for two consecutive weeks. In experiment 1, four groups of rats (n=12) were given AOM after 3 weeks of consuming the AIN-76 (control group) and RS diets. In experiment 2, four groups of rats (n=12) were given AOM before 3 weeks of consuming the AIN-76 and RS diets. Rats were killed after 13 weeks of initial injecting AOM. Colons were fixed in formalin and ACF were quantified after staining. In experiment 1, rats fed RS had more ACF than that of the control fed rats. In experiment 2, rats fed RS had fewer ACF than that of the control fed rats. The results indicate that dietary RS suppresses AOM-induced ACF formation, only at the P stage. A significant dose-response effect was observed between suppression of ACF formation and dietary RS amount. However, RS promote the formation of ACF at the PI stage.

Aberrant crypt foci in the adenoma prevention with celecoxib trial

Aberrant crypt foci (ACF) are the earliest visible neoplastic lesions in the colorectum. The natural history of these lesions and their role in the adenoma-carcinoma sequence are unknown. We studied ACF in a subset of patients randomized to placebo (n = 17), celecoxib (200 mg twice daily; n = 15), or celecoxib (400 mg twice daily; n = 13) in the Adenoma Prevention with Celecoxib (APC) trial. Magnification chromoendoscopy was done to identify, count, and biopsy ACF within the rectum at baseline and after 8 to 12 months of treatment. A total of 655 ACF were identified in 45 patients. We examined 70 of these ACF histologically, and all 70 were nondysplastic. Cohort characteristics and APC trial treatment results for substudy patients were similar to those of the overall APC trial. There was no significant modulation of ACF by celecoxib (versus placebo; P = 0.77). Immunohistochemical comparison of ACF with adjacent normal mucosa showed that ACF had an increased proliferative index as determined by Ki-67 (P < 0.0001), but lacked other features of neoplasia such as increased cyclooxygenase-2 expression and microvessel density, nuclear localization of beta-catenin, or decreased expression of the tumor suppressors SMAD4, Estrogen Receptor alpha, or MGMT. Only baseline SMAD4 expression in ACF correlated with posttreatment adenoma recurrence (independent of treatment arm; P = 0.01). The presence or number of nondysplastic ACF did not correlate with a higher risk of synchronous advanced or recurrent adenomas. Our overall results indicated that nondysplastic ACF were not accurate surrogate endpoint biomarkers of recurrent colorectal adenomas in the APC trial.

Protective versus promotional effects of white tea and caffeine on PhIP-induced tumorigenesis and beta-catenin expression in the rat

A 1 year carcinogenicity bioassay was conducted in rats treated with three short cycles of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)/high-fat (HF) diet, followed by 2% white tea (wt/vol), 0.05% epigallocatechin-3-gallate (EGCG) or 0.065% caffeine as sole source of fluid intake. Thirty-two percent of the PhIP/HF controls survived to 1 year, compared with 50, 48.7 and 18.2% in groups given white tea, EGCG and caffeine, respectively. After 1 year, PhIP/HF controls had tumors in the colon, skin, small intestine, Zymbal's gland, salivary gland and pancreas. For all sites combined, excluding the colon, tumor incidence data were as follows: PhIP/HF 69.5%, PhIP/HF + EGCG 48.7%, PhIP/HF + white tea 46.9% and PhIP/HF + caffeine 13.3%. Unexpectedly, a higher incidence of colon tumors was detected in rats post-treated with white tea (69%) and caffeine (73%) compared with the 42% incidence in PhIP/HF controls. In the colon tumors, beta-catenin mutations were detected at a higher frequency after caffeine posttreatment, and there was a shift toward more tumors harboring substitutions of Gly34 with correspondingly high protein and messenger RNA expression seen for both beta-catenin and c-Myc. c-Myc expression exhibited concordance with tumor promotion, and there was a concomitant increase in cell proliferation versus apoptosis in colonic crypts. A prior report described suppression of PhIP-induced colonic aberrant crypts by the same test agents, but did not incorporate a HF diet. These findings are discussed in the context of epidemiological data which do not support an adverse effect of tea and coffee on colon tumor outcome-indeed, some such studies suggest a protective role for caffeinated beverages.

Hyperplastic and serrated polyps of the colorectum

The serrated polyp pathway is a histopathological sequence that begins in a hyperplastic polyp, or precursor serrated aberrant crypt focus, and has the potential to end in a colonic adenocarcinoma that is CIMP-high and, in most cases, also MSI. An activating mutation of the BRAF oncogene is a marker for this pathway. There is evidence that aberrant CpG-island methylation is the molecular engine that drives the progression through sequential steps of the pathway, from hyperplastic polyp to a form of atypical hyperplastic polyp (termed sessile serrated adenoma) to dysplastic serrated polyp and, ultimately to serrated carcinoma. A second serrated pathway, identified by mutations of KRAS in serrated adenoma, is delineated less completely. Its endpoint is a colorectal carcinoma that is CIMP-low and MSS, and both the advanced serrated adenoma and carcinoma stages of this pathway show molecular genetic and morphologic features that overlap with those of the conventional APC carcinogenic pathway. Clinical studies are needed to elucidate the natural history of serrated neoplasia, and provide evidence-based guidance for risk assessment and surveillance of individuals discovered to harbor its various serrated polyp precursors.

Mutations in BRAF and KRAS differentially distinguish serrated versus non-serrated hyperplastic aberrant crypt foci in humans

We previously reported that colon carcinomas, adenomas, and hyperplastic polyps exhibiting a serrated histology were very likely to possess BRAF mutations, whereas when these same advanced colonic lesions exhibited non-serrated histology, they were wild type for BRAF; among hyperplastic polyps, KRAS mutations were found mainly in a non-serrated variant. On this basis, we predicted that hyperplastic aberrant crypt foci (ACF), a putative precancerous lesion found in the colon, exhibiting a serrated phenotype would also harbor BRAF mutations and that non-serrated ACF would not. In contrast, KRAS mutations would be found more often in the non-serrated ACF. We examined 55 ACF collected during screening colonoscopy from a total of 28 patients. Following laser capture microdissection, DNA was isolated, and mutations in BRAF and KRAS were determined by direct PCR sequencing. When hyperplastic lesions were further classified into serrated and non-serrated histologies, there was a strong inverse relationship between BRAF and KRAS mutations: a BRAF(V600E) mutation was identified in 10 of 16 serrated compared with 1 of 33 non-serrated lesions (P = 0.001); conversely, KRAS mutations were present in 3 of 16 serrated compared with 14 of 33 non-serrated lesions. Our finding of a strong association between BRAF mutations and serrated histology in hyperplastic ACF supports the idea that these lesions are an early, sentinel, or a potentially initiating step on the serrated pathway to colorectal carcinoma.