Aberrant crypt foci of the colon as precursors of adenoma and cancer

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.

Effect of Lactobacillus acidophilus KFRI342 on the development of chemically induced precancerous growths in the rat colon

Lactobacillus acidophilus KFRI342, isolated from the Korean traditional food kimchi, was investigated for its suitability as a dietary probiotic. The effects of L. acidophilus KFRI342 on the development of chemically induced (1,2-dimethylhydrazine; DMH) precancerous cytological changes of the colon were investigated in rats. Forty-five male F344 rats were randomly divided into three dietary groups. The control group received a high-fat diet (HF), a second group received a high-fat diet containing the carcinogen (HFC), and a final group received a high-fat diet containing the carcinogen and L. acidophilus KFRI342 (HFCL). L. acidophilus KFRI342 was administered orally three times per week at 2×10(9) c.f.u. ml(-1). L. acidophilus KFRI342 treatments decreased the number of Escherichia coli in faecal samples, the enzyme activities of β-glucuronidase and β-glucosidase, and plasma triglyceride concentration compared to the HF and HFC treatments (P<0.05). L. acidophilus KFRI342 consumption also decreased the ratio of aberrant crypts to aberrant crypt foci incidence and the number of aberrant crypts in HFCL rats. Therefore, L. acidophilus showed potential probiotic activity as an inhibitor of DMH-induced symptoms in live rats. Our in vivo studies indicate that L. acidophilus from kimchi may be suitable as a probiotic for human use.

Copy number aberrations in benign serous ovarian tumors: a case for reclassification?

PURPOSE

Serous ovarian carcinomas are the predominant epithelial ovarian cancer subtype and it has been widely believed that some or all of these may arise from precursors derived from the ovarian surface epithelium or fimbriae, although direct molecular evidence for this is limited. This study aimed to conduct copy number (CN) analysis using a series of benign and borderline serous ovarian tumors to identify underlying genomic changes that may be indicative of early events in tumorigenesis.

EXPERIMENTAL DESIGN

High resolution CN analysis was conducted on DNA from the epithelial and fibroblast components of a cohort of benign (N = 39) and borderline (N = 24) serous tumors using the Affymetrix OncoScan assay and SNP6.0 arrays.

RESULTS

CN aberrations were detected in the epithelium of only 2.9% (1 of 35) of serous cystadenomas and cystadenofibromas. In contrast, CN aberrations were detected in the epithelium of 67% (16 of 24) of the serous borderline tumors (SBT). Unexpectedly, CN aberrations were detected in the fibroblasts of 33% (13 of 39) of the benign serous tumors and in 15% (3 of 20) of the SBTs. Of the 16 cases with CN aberrations in the fibroblasts, 12 of these carried a gain of chromosome 12.

CONCLUSIONS

Chromosome 12 trisomy has been previously identified in pure fibromas, supporting the concept that a significant proportion of benign serous tumors are in fact primary fibromas with an associated cystic mass. This is the first high resolution genomic analysis of benign serous ovarian tumors and has shown not only that the majority of benign serous tumors have no genetic evidence of epithelial neoplasia but that a significant proportion may be more accurately classified as primary fibromas.

Intestinal tumorigenesis is not affected by progesterone signaling in rodent models

Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR) is not expressed. Expression was confined to sporadic mesenchymal cells. To analyze the influence of systemic progesterone receptor signaling, we crossed mice that lacked the progesterone receptor (PRKO) to the Apc^Min/+ mouse, a model for spontaneous intestinal polyposis. PRKO-Apc^Min/+mice exhibited no change in polyp number, size or localization compared to Apc^Min/+. To examine effects of progestins on the intestinal epithelium that are independent of the PR, we treated mice with MPA. We found no effects of either progesterone or MPA on gross intestinal morphology or epithelial proliferation. Also, in rats treated with MPA, injection with the carcinogen azoxymethane did not result in a difference in the number or size of aberrant crypt foci, a surrogate end-point for adenoma development. We conclude that expression of the progesterone receptor is limited to cells in the intestinal mesenchyme. We did not observe any effect of progesterone receptor signaling or of progestin treatment in rodent models of intestinal tumorigenesis.

Colorectal carcinogenesis: Review of human and experimental animal studies

This review gives a comprehensive overview of cancer development and links it to the current understanding of tumorigenesis and malignant progression in colorectal cancer. The focus is on human and murine colorectal carcinogenesis and the histogenesis of this malignant disorder. A summary of a model of colitis-associated colon tumorigenesis (an AOM/DSS model) will also be presented. The earliest phases of colorectal oncogenesis occur in the normal mucosa, with a disorder of cell replication. The large majority of colorectal malignancies develop from an adenomatous polyp (adenoma). These can be defined as well-demarcated masses of epithelial dysplasia, with uncontrolled crypt cell proliferation. When neoplastic cells pass through the muscularis mucosa and infiltrate the submucosa, they are malignant. Carcinomas usually originate from pre-existing adenomas, but this does not imply that all polyps undergo malignant changes and does not exclude de novo oncogenesis. Besides adenomas, there are other types of pre-neoplasia, which include hyperplastic polyps, serrated adenomas, flat adenomas and dysplasia that occurs in the inflamed colon in associated with inflammatory bowel disease. Colorectal neoplasms cover a wide range of pre-malignant and malignant lesions, many of which can easily be removed during endoscopy if they are small. Colorectal neoplasms and/or pre-neoplasms can be prevented by interfering with the various steps of oncogenesis, which begins with uncontrolled epithelial cell replication, continues with the formation of adenomas and eventually evolves into malignancy. The knowledge described herein will help to reduce and prevent this malignancy, which is one of the most frequent neoplasms in some Western and developed countries.

Pathophysiological Roles of PPARgamma in Gastrointestinal Epithelial Cells

Although the highest levels of PPARγ expression in the body have been reported in the gastrointestinal epithelium, little is known about the physiological functions of that receptor in the gut. Moreover, there is considerable controversy concerning the effects of thiazolidinedione PPARγ agonists on the two major diseases of the gastrointestinal track: colorectal cancer and inflammatory bowel disease. We will undertake to review both historical and recently published data with a view toward summarizing what is presently known about the roles of PPARγ in both physiological and pathological processes in the gastrointestinal epithelium.

Investigation of the prevalence and number of aberrant crypt foci associated with human colorectal neoplasm

BACKGROUND

Aberrant crypt foci (ACF) are considered to be useful as surrogate biomarker for colorectal cancer (CRC), but the biological significance of ACF remains controversial. We attempted to investigate the relationship between the presence of ACF and human colorectal carcinogenesis using a relatively large sample size.

METHODS

We carried out high-magnification chromoscopic colonoscopy to identify ACFs in 861 subjects undergoing a diagnostic endoscopy at the Yokohama City University Hospital. The present study compared the prevalence and number of ACFs in three subject groups (normal subjects, adenoma cases, and CRC cases). The correlations between the demographic and behavioral characteristics of the subjects and the prevalence of ACFs were also assessed.

RESULTS

The prevalence of ACF was 64%, 88%, and 95%, and the mean number of ACF was 3.6, 6.2, and 10.1, in normal subjects, adenoma cases, and CRC cases, respectively. When differences in the prevalence and number of ACFs among age- and sex-stratified subject groups were examined, significant stepwise increments from normal subjects to adenoma cases to CRC cases were apparent (P < 0.001). Moreover, an age- and sex-adjusted multiple logistic regression analysis revealed that smoking and alcohol habits had a synergistic effect, increasing the prevalence of ACFs as well as the risk of CRC (P < 0.001).

CONCLUSIONS

These results suggested that ACF may serve as a reliable surrogate biomarker for human colorectal carcinogenesis.

IMPACT

The use of ACF as an endpoint may enable the size, duration, and cost of CRC chemoprevention studies to be reduced.

Phase IIa clinical trial of curcumin for the prevention of colorectal neoplasia

Curcumin is derived from the spice tumeric and has antiinflammatory and antineoplastic effects in vitro and in animal models, including preventing aberrant crypt foci (ACF) and adenomas in murine models of colorectal carcinogenesis. Inhibiting the production of the procarcinogenic eicosanoids prostaglandin E₂ (PGE₂) and 5-hydroxyeicosatetraenoic acid (5-HETE) can suppress carcinogenesis in rodents. Curcumin reduces mucosal concentrations of PGE₂ (via inhibition of cyclooxygenases 1 and 2) and 5-HETE (via inhibition of 5-lipoxygenase) in rats. Although preclinical data support curcumin activity in many sites, the poor bioavailability reported for this agent supports its use in the colorectum. We assessed the effects of oral curcumin (2 g or 4 g per day for 30 days) on PGE₂ within ACF (primary endpoint), 5-HETE, ACF number, and proliferation in a nonrandomized, open-label clinical trial in 44 eligible smokers with eight or more ACF on screening colonoscopy. We assessed pre- and posttreatment concentrations of PGE₂ and 5-HETE by liquid chromatography tandem mass spectroscopy in ACF and normal-tissue biopsies; ACF number via rectal endoscopy; proliferation by Ki-67 immunohistochemistry; and curcumin concentrations by high-performance liquid chromatography in serum and rectal mucosal samples. Forty-one subjects completed the study. Neither dose of curcumin reduced PGE₂ or 5-HETE within ACF or normal mucosa or reduced Ki-67 in normal mucosa. A significant 40% reduction in ACF number occurred with the 4-g dose (P < 0.005), whereas ACF were not reduced in the 2-g group. The ACF reduction in the 4-g group was associated with a significant, five-fold increase in posttreatment plasma curcumin/conjugate levels (versus pretreatment; P = 0.009). Curcumin was well tolerated at both 2 g and 4 g. Our data suggest that curcumin can decrease ACF number, and this is potentially mediated by curcumin conjugates delivered systemically.

Prebiotic treatment reduced preneoplastic lesions through the downregulation of toll like receptor 4 in a chemo-induced carcinogenic model

Germinated barley foodstuff contains prebiotics which are reported to have anti-cancerous effects in colorectal cancer model, but the detailed mechanism remains unclear. Recent studies revealed that the role of microbiota was strongly related to the regulation of incidence and progression of colorectal cancer. The aim of this study was to examine the anti-neoplastic mechanism by prebiotics. Azoxymethane treated F344 rats were used as the sporadic cancerous model. After azoxymethane injection, either a control or germinated barley foodstuff diet was administered to the rats for another 5 weeks, and the number of abberant crypt foci, toll like receptor 4, Kirsten rat sarcoma viral oncogene homolog, adenomatous polyposis coli tumor suppressor gene and cyclooxygenase 2 mRNA expression of colonic mucosa and cecal short chain fatty acids were examined. The germinated barley food stuff significantly attenuated the number of abberant crypt focis and the expression of toll like receptor 4 and cyclooxygenase 2 mRNA, compared to the control group. In addition, the cecal butyrate production in the germinated barley foodstuff group was significantly higher than that in the control. In conclusion, this prebiotic treatment for colorectal cancer may be useful without causing the adverse effects seen in either anti-cancer drugs or anti-inflammatory drugs.

Prognostic value of colorectal cancer biomarkers

Despite the large amount of data in cancer biology and many studies into the likely survival of colorectal cancer (CRC) patients, knowledge regarding the issue of CRC prognostic biomarkers remains poor. The Tumor-Node-Metastasis (TNM) staging system continues to be the most powerful and reliable predictor of the clinical outcome of CRC patients. The exponential increase of knowledge in the field of molecular genetics has lead to the identification of specific alterations involved in the malignant progression. Many of these genetic alterations were proposed as biomarkers which could be used in clinical practice to estimate CRC prognosis. Recently there has been an explosive increase in the number of putative biomarkers able to predict the response to specific adjuvant treatment. In this review we explore and summarize data concerning prognostic and predictive biomarkers and we attempt to shed light on recent research that could lead to the emergence of new biomarkers in CRC.

Randomized double-blind trial of sulindac and etodolac to eradicate aberrant crypt foci and to prevent sporadic colorectal polyps

PURPOSE

On the basis of the results of our preliminary trial suggesting that aberrant crypt foci (ACF) could be eradicated by short-term administration of sulindac, in the present study, we explored the feasibility of using ACF as surrogate markers for chemoprevention of colorectal cancer.

EXPERIMENTAL DESIGN

Randomly assigned to sulindac (300 mg daily), etodolac (400 mg daily), and placebo groups were 189 subjects without polyps or who had undergone polypectomy. Drugs were administered for 2 months. ACF in the rectal region were counted by magnifying endoscopy. Occurrence of polyps was evaluated at 12 months. A planned interim analysis was conducted.

RESULTS

ACF number at 2 months was significantly suppressed in the sulindac group (P = 0.0075), but not in the etodolac group (P = 0.73). In the sulindac group, the numbers of adenomas plus hyperplastic polyps (total polyps) and adenomas at 12 months were significantly (P = 0.02) and marginally (P = 0.064) lower, respectively, in comparison with the placebo group; no such difference was observed in the etodolac group. In analysis of only polypectomized subjects, the numbers of total polyps and adenomas in the sulindac group were even more markedly lower, with P values of 0.014 and 0.034, respectively. A similar tendency was confirmed by analyses of the incidence of polyps at 12 months. Suppression rates of total polyps and adenomas in ACF responders to sulindac were significantly greater than in nonresponders. In all groups, compliance was more than 90% and no intolerable adverse effects were observed.

CONCLUSIONS

ACF may be useful as surrogate lesions for chemoprevention of colorectal cancer.

Affibody-functionalized gold-silica nanoparticles for Raman molecular imaging of the epidermal growth factor receptor

The affibody functionalization of fluorescent surface-enhanced Raman scattering gold-silica nanoparticles as multimodal contrast agents for molecular imaging specific to epidermal growth factor receptor (EGFR) is reported. This nanoparticle bioconjugate reports EGFR-positive A431 tumors with a signal nearly 35-fold higher than EGFR-negative MDA-435S tumors. The low-level EGFR expression in adjacent healthy tissue is 7-fold lower than in the positive tumors. Validation via competitive inhibition reduces the signal by a factor of six, and independent measurement of EGFR via flow cytometry correlates at R(2) = 0.92.

EGFR(s) in aging and carcinogenesis of the gastrointestinal tract

Cells of the gastrointestinal (GI) mucosa are subject to a constant process of renewal which, in normal adults, reflects a balance between the rates of cell production and cell loss. Detailed knowledge of these events is, therefore, essential for a better understanding of the normal aging processes as well as many GI diseases, particularly malignancy, that represent disorders of tissue growth. In general, many GI dysfunctions, including malignancy, increase with advancing age, and aging itself is associated with alterations in structural and functional integrity of the GI tract. Although the regulatory mechanisms for age-related increase in the incidence of GI-cancers are yet to be fully delineated, recent evidence suggests a role for epidermal growth family receptors and its family members {referred to as EGFR(s)} in the development and progression of carcinogenesis during aging. The present communication discusses the involvement of EGFR(s) in regulating events of GI cancers during advancing age and summarizes the current available therapeutics targeting these receptors. The current review also describes the effectiveness of ErbB inhibitors as well as combination therapies. Additionally, the involvement of GI stem cells in the development of the age-related rise in GI cancers is emphasized.

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.

Light-scattering technologies for field carcinogenesis detection: a modality for endoscopic prescreening

Colonoscopy has revolutionized colorectal cancer (CRC) screening resulting in a decrease in both CRC mortality and incidence. Despite this, CRC still ranks as the second leading cause of cancer deaths among Americans underscoring the need to both increase availability and accuracy of colonoscopy. The latter considerations provide the impetus for much of the current research into adjunctive imaging technologies. Recent advances in improving detection of dysplasia that have translated into clinical practice include high-definition scopes, narrow-band imaging, and chromo-endoscopy. Another major direction of research into improving endoscopy is determining histology of lesions in situ (“optical biopsy”) with confocal endomicroscopy, fluorescence and elastic scattering spectroscopy. All these techniques are of great promise in improving delivery of endoscopy but, to date, have not addressed the potentially more important hurdle associated with logistic challenges of providing accurate CRC screening for the entire at-risk population.

Molecular mechanisms for chemoprevention of colorectal cancer by natural dietary compounds

Colorectal cancer is one of the major causes of cancer-related mortality in both men and women worldwide. This review focuses on preventing the initiation and promotion of neoplastic growth in colorectal cancer, particularly with natural dietary compounds. Chemoprevention is defined as the use of natural dietary compounds and/or synthetic substances that can delay, prevent, or even reverse the development of adenomas, as well as the progression from adenoma to carcinoma. The molecular mechanisms of their chemopreventive action are associated with the modulation of signaling cascades, gene expressions involved in the regulation of cell proliferation, differentiation, and apoptosis and the suppression of chronic inflammation, metastasis, and angiogenesis. Here, we summarize the currently known targets and signaling pathways whereby natural dietary compounds interfere with the development of colorectal cancer, and thus providing evidence for these substances in colonic cancer chemopreventive action.

[Aberrant crypt foci and cancer of the colorectal junction: the correlation between beta-catenin/Ki-67 expression and the occurrence of early microscopic secondary lesions surrounding periphery colorectal cancer]

OBJECTIVE

To evaluate the occurrence of aberrant crypt foci (ACF) in macroscopic normal mucosa surrounding colorectal cancers (CRC); additionally, analyze tumor progression from ACF to CRC by means of beta-catenin and Ki-67 expression.

METHODS

Twenty-one surgical specimens showing colorectal junction adenocarcinoma were included. Macroscopic normal mucosa proximal and distal to the primary tumor was sampled at a distance of 1 and 5 cm in both sides. A primary tumor sample was also retrieved. Eventually, ACF's were selected and immunohistochemical analysis of beta-catenin and Ki-67 were carried out.

RESULTS

Among all adenocarcinoma samples, the frequency of positive â-catenin nuclear expression was 81%. The Ki-67 expression demonstrated the same percentage of positivity as did beta-catenin. However, the Kappa coefficient showed weak relationship between those two antibodies. Among 20 ACF's analyzed, 13 were located close (1 cm) to the tumor. None of the ACF's demonstrated nuclear expression of beta-catenin or Ki-67.

CONCLUSION

Higher concentrations of ACF's were observed in colonic mucosa at a distance of 1 cm compared to samples at 5 cm from the primary CRC. However, we could not demonstrate positive correlation between colonocytes beta-catenin expression and the occurrence of ACF's.

Attenuated familial adenomatous polyposis: results from an international collaborative study

AIM

The study aimed to describe genetical and clinical features of attenuated familial adenomatous polyposis (AFAP) and to propose clinical criteria and guidelines for treatment and surveillance.

METHOD

A questionnaire study was carried out of polyposis registries with data on patients with presumed AFAP, defined as having ≤ 100 colorectal adenomas at age ≥ 25.

RESULTS

One hundred and ninety-six patients were included. The median number of adenomas was 25 (0-100) with a uniform distribution of colorectal adenomas and carcinomas (CRC). Age at CRC diagnosis was delayed by 15 years compared with classic FAP. Eighty-two patients had a colectomy and an ileorectal anastomosis and 5/82 (6%) had a secondary proctectomy. The location of the mutation in the APC gene was known in 69/171 (40%) tested patients. Only 15/29 (52%) of mutations in APC were found in parts of the gene usually associated with AFAP (the 5' end, exon 9 and 3' end).

CONCLUSIONS

A subset of FAP patients with a milder phenotype does exist and treatment and surveillance had to be modified accordingly. The mutation detection rate is lower than in classic FAP and mutations in AFAP patients are located throughout the APC gene. We propose the following clinical diagnostic criteria for AFAP: a dominant mode of inheritance of colorectal adenomatosis and <100 colorectal adenomas at age 25 or older. Colonoscopy had to be preferred to sigmoidoscopy and surveillance had to be life-long. In the majority of patients, prophylactic colectomy and ileorectal anastomosis are recommended at the age of 20-25 years.

Aberrant crypt foci: the case for inclusion as a biomarker for colon cancer

Aberrant crypt foci (ACF) are one of the earliest histopathological manifestations of colon cancer. In this review, we critically present the molecular, cellular, histopathological, and chemopreventive evidence that ACF are relevant biomarkers for colon cancer. The laboratory and clinical evidence are highly suggestive that ACF are in the pathway leading to colon cancer, but not all ACF will do so. The possible fate and outcome of ACF in the progression toward colon cancer may be dependent on a number of features that define their predictive power for the prevention or progression of cancer.

Metformin suppresses colorectal aberrant crypt foci in a short-term clinical trial

The biguanide metformin is widely used for treating diabetes mellitus. We previously showed the chemopreventive effect of metformin in two rodent models of colorectal carcinogenesis. However, besides epidemiologic studies, little is known about the effects of metformin on human colorectal carcinogenesis. The objective of this pilot study was to evaluate the chemopreventive effect of metformin on rectal aberrant crypt foci (ACF), which are an endoscopic surrogate marker of colorectal cancer. We prospectively randomized 26 nondiabetic patients with ACF to treatment with metformin (250 mg/d, n = 12) or no treatment (control, n = 14); 23 patients were evaluable for end point analyses (9 metformin and 14 control); the two groups were similar in ACF number and other baseline clinical characteristics. Magnifying colonoscopy determined the number of rectal ACF in each patient at baseline and after 1 month in a blinded fashion (as were all laboratory end point analyses). We also examined proliferative activity in colonic epithelium (via proliferating cell nuclear antigen labeling index) and apoptotic activity (via terminal deoxynucleotidyl transferase dUTP nick-end labeling). At 1 month, the metformin group had a significant decrease in the mean number of ACF per patient (8.78 +/- 6.45 before treatment versus 5.11 +/- 4.99 at 1 month, P = 0.007), whereas the mean ACF number did not change significantly in the control group (7.23 +/- 6.65 versus 7.56 +/- 6.75, P = 0.609). The proliferating cell nuclear antigen index was significantly decreased and the apoptotic cell index remained unaltered in normal rectal epithelium in metformin patients. This first reported trial of metformin for inhibiting colorectal carcinogenesis in humans provides preliminary evidence that metformin suppresses colonic epithelial proliferation and rectal ACF formation in humans, suggesting its promise for the chemoprevention of colorectal cancer.

Molecular alterations associated with sulindac-resistant colon tumors in ApcMin/+ mice

Although nonsteroidal anti-inflammatory drugs (NSAID), including sulindac, have been used extensively as chemopreventive agents for colorectal cancer, results are not consistent. NSAIDs, most reportedly sulindac, often do not cause a complete regression of adenomas and some patients develop resistance to NSAID treatment. In this study, we evaluated the effect of sulindac on colon tumorigenesis in the Apc(Min/+) mouse model. Sulindac (180 ppm) given in drinking water for 9 weeks to Apc(Min/+) mice significantly reduced the size of colon tumors, but actually caused an increase in colon tumor multiplicity relative to untreated controls (average of 5.5 versus 1.6 tumors per mouse, respectively; P < 0.0001). This indicated that the drug could inhibit colon tumor progression but not initiation. As expected, in the small intestine, sulindac significantly reduced tumor size and multiplicity relative to untreated controls (average of 2.3 versus 42.0 tumors per mouse, respectively; P < 0.0001). Generation of a panel of prostanoids was comparably suppressed in the small intestine and colon by sulindac treatment. Sulindac is also known to exert its growth inhibitory effects through regulation of many noncyclooxygenase targets, including p21, beta-catenin, E-cadherin, mitochondrial apoptotic proteins, and peroxisome proliferator-activated receptor-gamma. We found that sulindac treatment protected against E-cadherin loss in colon tumors, with associated inhibition of nuclear beta-catenin accumulation. Importantly, p21(WAF1/cip1) and peroxisome proliferator-activated receptor-gamma expression were absent in colon tumors from sulindac-treated mice, suggesting that loss of these proteins is necessary for drug resistance. Together, these observations may be translatable to designing novel clinical therapies using combinations of agents that target multiple molecular pathways to overcome sulindac resistance.

PPARgamma Ligand as a Promising Candidate for Colorectal Cancer Chemoprevention: A Pilot Study

Activating synthetic ligands for peroxisome proliferator-activated receptor gamma (PPARγ), such as pioglitazone, are commonly used to treat persons with diabetes mellitus with improvement of insulin resistance. Several reports have clearly demonstrated that PPARγ ligands could inhibit colorectal cancer cell growth and induce apoptosis. Meanwhile, aberrant crypt foci (ACF) have come to be established as a biomarker of the risk of CRC in azoxymethane-treated mice and rats. In humans, ACF can be detected using magnifying colonoscopy. Previously, CRC and adenoma were used as a target for chemopreventive agents, but it needs a long time to evaluate, however, ACF can be a surrogate marker of CRC even for a brief period. In this clinical study, we investigated the chemopreventive effect of pioglitazone on the development of human ACF as a surrogate marker of CRC. Twenty-nine patients were divided into two groups, 20 were in the endoscopically normal control group and 9 were in the pioglitazone (15 mg/day) group, and ACF and adenoma were examined before and after 1-month treatment. The number of ACF was significantly decreased (5.8 ± 1.1 to 3.3 ± 2.3) after 1 month of pioglitazone treatment, however, there was no significant change in the number of crypts/ACF or in the number and size of adenomas. Pioglitazone may have a clinical application as a cancer-preventive drug. This investigation is just a pilot study, therefore, further clinical studies are needed to show that the PPARγ ligand may be a promising candidate as a chemopreventive agent for colorectal carcinogenesis.

Ursodeoxycholic acid and chemoprevention of colorectal cancer

Colorectal cancer is respectively the third and second most common cancer among men and women in France. Interest in chemoprevention for colorectal cancer has increased over the last two decades. Beside non-steroidal anti-inflammatory drugs, ursodeoxycholic acid (UDCA) may have chemopreventive action in colorectal cancer with a likely better tolerance. In high-risk populations such as patients with inflammatory bowel disease or prior colorectal adenoma or carcinoma, retrospective and prospective studies have suggested a beneficial effect of UDCA. In azoxymethane model, UDCA inhibits tumor development by countering the tumor-promoting effects of secondary bile acids, such as deoxycholic acid (DCA). The opposing effects of UDCA and DCA on lipid raft composition may be central to their effects on colonic tumorigenesis. Differential effects of DCA and UDCA on growth factor and inflammatory signals involved in colorectal carcinogenesis, such as epidermal growth factor receptors (EGFR) signaling and Cox-2 expression, likely mediate their opposing effects on colonic tumor promotion and tumor inhibition, respectively.

Metformin suppresses azoxymethane-induced colorectal aberrant crypt foci by activating AMP-activated protein kinase

Metformin is widely used for the treatment of diabetes mellitus. Adenosine monophosphate-activated protein kinase (AMPK) is known to be activated by metformin and to inhibit the mammalian target of rapamycin (mTOR) pathway. The mTOR pathway plays an important role in the protein translational machinery and cell proliferation. We examined the effect of metformin on the suppression of colorectal carcinogenesis in chemical carcinogen-induced models. Seven-wk-old BALB/c mice were intraperitoneally (i.p.) injected with azoxymethane (AOM, 10 mg/kg) and then treated with or without metformin (250 mg/kg/d) for 6 wk (for the investigation of aberrant crypt foci [ACF] formation) or 32 wk (for polyp formation). We next investigated colonic epithelial proliferation using bromodeoxyuridine (BrdU) and the proliferating cell nuclear antigen (PCNA) labeling indices. Furthermore, to examine the indirect effect of metformin, the insulin resistance status and the serum lipid levels were assessed. Treatment with metformin significantly reduced ACF formation. The effect of metformin on colon polyp inhibition was relatively modest. No significant difference in body weight or glucose concentration was observed. The BrdU and PCNA indices decreased in mice treated with metformin. A Western blot analysis revealed that the phosphorylated mTOR, S6 kinase, and S6 protein levels in the colonic mucosa decreased significantly in mice treated with metformin. In conclusion, metformin suppresses colonic epithelial proliferation via the inhibition of the mTOR pathway through the activation of AMPK. As metformin is already used daily as an antidiabetic drug, it might be a safe and promising candidate for the chemoprevention of colorectal cancer.

Increased frequency of serrated aberrant crypt foci among smokers

OBJECTIVES

The American College of Gastroenterology has published guidelines recently that suggest that smokers with a history of >20 pack years may need screening for colorectal cancer (CRC) at an earlier age than non-smokers. Aberrant crypt foci (ACF) may represent important precursors for colorectal neoplasms and potential surrogate biomarkers. Clarifying the role of ACF in relation to known CRC risk factors such as smoking may have important implications for screening as well as our understanding of tobacco use and colorectal carcinogenesis. Our goal was to examine whether smoking at least 20 pack years was associated with an increased frequency of ACF.

METHODS

We gathered detailed smoking history, personal and family history of CRC, and other epidemiologic data (age, gender, height, weight, ethnicity, and medication use) from 125 patients undergoing routine screening or surveillance colonoscopy. We used a magnifying colonoscope (Olympus Close Focus Colonoscope XCF-Q160ALE, Olympus Corporation, Tokyo, Japan) and examined the distal 20 cm section of colon after staining with 0.5% methylene blue. ACF were counted and characterized histologically. Hyperplastic ACF were further characterized as either serrated or non-serrated.

RESULTS

Smoking at least 20 pack years was associated with an increased likelihood (adjusted odds ratio (OR)=3.45; 95% confidence interval (CI)=1.93-6.18) of having more than the median number of ACF (> or = 15) compared with non-smokers. Similarly, patients with a personal history of advanced neoplasia were more likely (adjusted OR=3.42; 95% CI=1.01-11.67) to have a greater than median number of ACF compared with patients without this diagnosis. Smokers were more likely than non-smokers to have serrated ACF (P=0.002).

CONCLUSIONS

Smoking at least 20 pack years seems to be associated with increased number of ACF in the rectum and distal sigmoid, especially those with serrated histology. Our data support ACG guidelines for earlier screening for CRC among smokers and add to our understanding of how colorectal carcinogenesis is related to tobacco use.

One year recurrence of aberrant crypt foci

Aberrant crypt foci (ACF) are putative precursors of colorectal adenomas and have been postulated as a potential biomarker for colorectal cancer. Few studies have followed subjects after ACF removal to monitor recurrence. Subjects enrolled in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial were recruited for a study of ACF. A standardized protocol using magnified endoscopy and mucosal staining with methylene blue was implemented to detect rectal ACF. After removal of all baseline ACF, subjects returned 1 year later and recurrent ACF were observed and biopsied. A total of 434 of 505 (86%) subjects observed at baseline returned for the year 1 exam. The mean number of ACF at year 1 was strongly correlated with the number at baseline; subjects with 0, 1, 2 to 3, 4 to 6, and 7+ ACF at baseline had a mean of 1.2, 1.4, 1.7, 3.0, and 5.5 ACF, respectively, at year 1. ACF prevalence and mean count at year 1 (61% and 1.93, respectively), were only slightly lower than the corresponding values at year 0 (69% and 2.25, respectively). The locations of ACF at year 1 and baseline were significantly correlated. Of 96 ACF assessed for histology, 70 (73%) were hyperplastic and none were dysplastic. After removal of ACF at baseline, ACF counts 1 year later were only slightly reduced and were significantly correlated with the baseline ACF count. The results of this study do not support a role for ACF in clinical practice.

Optical measurement of rectal microvasculature as an adjunct to flexible sigmoidosocopy: gender-specific implications

Flexible sigmoidoscopy is a robust, clinically validated, and widely available colorectal cancer screening technique that is currently sanctioned by major guideline organizations. Given that endoscopic visualization is generally limited to the distal third of the colon and women tend to have a proclivity for proximal lesions, the flexible sigmoidoscopy performance is markedly inferior in women than in men. Our group has shown that by using a novel light-scattering approach, we were able to detect an early increase in blood supply (EIBS) in the distal colonic mucosa, which served as a marker of field carcinogenesis and, hence, proximal neoplasia. Therefore, we sought to ascertain whether rectal EIBS would improve flexible sigmoidoscopy, especially in women. A polarization-gated spectroscopy fiber-optic probe was used to assess EIBS in the endoscopically normal rectum (n = 366). When compared with gender-matched neoplasia-free controls, females with advanced proximal neoplasia (n = 10) had a robust (60%; P = 0.002) increase in rectal mucosal oxyhemoglobin content whereas the effect size in males was less marked (33%; P = 0.052). In women, addition of rectal oxyhemoglobin tripled the sensitivity for advanced neoplasia over flexible sigmoidoscopy alone. Indeed, the performance characteristics seemed to be excellent (sensitivity, 100%; specificity, 76.8%; positive predictive value, 32.6%; and negative predictive value, 100%). A variety of nonneoplastic factors were assessed and did not confound the relationship between rectal EIBS and advanced neoplasia. Therefore, using rectal EIBS in combination with flexible sigmoidoscopy mitigated the gender gap and may allow flexible sigmoidoscopy to be considered as a viable colorectal cancer screening test in women.

Mofezolac suppresses beef tallow-promoted colon carcinogenesis in rats

AIM: To investigate the effect of mofezolac, a selective cyclooxygenase (COX)-1 inhibitor, on beef tallow-promoted colon carcinogenesis in rats.

METHODS: One hundred and eight male Sprague-Dawley rats were used in this study. One group of rats were injected with azoxymethane (AOM) and fed diets containing different percentages of beef tallow (with or without 0.12% mofezolac) for 12 wk. Total aberrant crypt foci (ACF) and multicrypt ACF were counted to evaluate the effect of mofezolac on early carcinogenesis. Another group of rats were injected with AOM or saline and fed a 10% beef tallow diet (with or without 0.12% mofezolac) for 44 wk to evaluate the effect of mofezolac on tumor incidence and number. To explore the mechanism behind the effect of mofezolac on carcinogenesis, the proliferation of normal-appearing colonic mucosa surrounding the tumor was evaluated by BrdU incorporation assay, and the expression of β-catenin in the normal-appearing colonic mucosa was analyzed by Western blot.

RESULTS: At week 12, the number of ACF in the mofezolac group was significantly lower than that in the control group (P < 0.05). At week 44, tumor incidence and multiplicity were significantly lower in the mofezolac group than in the control group (66.7% vs 100%, and 2.5 ± 2.3 vs 5.3 ± 1.2, respectively; both P < 0.05). Proliferative cells were much fewer in the mofezolac group than in the control group (5 ± 0.82 vs 3.25 ± 0.50; 7.75 ± 0.96 vs 4.75 ± 0.50, both P < 0.05). Besides, the distribution of proliferative cells in saline- and AOM-treated rats was similar to that under physiological condition. Down-regulation of β-catenin expression was also observed in the mofezolac group when compared with the control group.

CONCLUSION: Mofezolac effectively suppresses beef tallow-promoted colon carcinogenesis in rats probably by down-regulating β-catenin expression and inhibiting colonic proliferation.

Conjugated linoleic acid suppresses colon carcinogenesis in azoxymethane-pretreated rats with long-term feeding of diet containing beef tallow

BACKGROUND

We have indicated previously that long-term feeding of beef tallow increases colorectal cancer in rats. In this study, we investigated the effects of conjugated linoleic acid (CLA) on colon carcinogenesis in rats under long-term feeding of beef tallow diets, pretreated with azoxymethane (AOM).

METHODS

Six-week-old male Sprague-Dawley rats were fed with 10% beef tallow diet only, 10% beef tallow with 1% CLA in triglyceride form (CLA-TG), or 10% beef tallow with 1% CLA in free fatty acid form (CLA-FFA). Colon carcinogenesis was induced by two intraperitoneal injections of AOM. Aberrant crypt foci (ACFs) were examined at 12 weeks. Cancer, cell proliferation, apoptosis, Wnt signaling, and the arachidonic acid cascade were examined at 44 weeks.

RESULTS

At 12 weeks, CLA-TG and CLA-FFA attenuated the increase in ACFs induced by 10% beef tallow and AOM pretreatment. At 44 weeks, both forms of CLA attenuated multiple colon cancers, and CLA-FFA reduced the incidence of colon cancer to 50% of that seen with CLA-TG. CLA-TG and CLA-FFA decreased the number of 5-bromo-2'-deoxyuridine-positive cells in AOM-pretreated rats fed with 10% beef tallow. CLA-FFA increased the number of apoptotic cells and the activity of caspase-3 in the colon mucosa, and CLA-TG enhanced the activity of caspase-3. Both forms of CLA suppressed Wnt signaling and the arachidonic acid cascade in rats treated with beef tallow and AOM.

CONCLUSION

These results suggested that CLA-TG and CLA-FFA suppressed colon carcinogenesis in rats with long-term feeding of a 10% beef tallow diet, through several mechanisms. The results of the present study with rats might be applicable to humans.

Oncogenic KRAS is not necessary for Wnt signalling activation in APC-associated FAP adenomas

Recent studies have suggested that APC loss alone may be insufficient to promote aberrant Wnt/beta-catenin signalling. Our aim was to comprehensively characterize Wnt signalling components in a set of APC-associated familial adenomatous polyposis (FAP) tumours. Sixty adenomas from six FAP patients with known pathogenic APC mutations were included. Somatic APC and KRAS mutations, beta-catenin immunostaining, and qRT-PCR of APC, MYC, AXIN2 and SFRP1 were analysed. Array-comparative genomic hybridization (aCGH) was also assessed in 26 FAP adenomas and 24 paired adenoma-carcinoma samples. A somatic APC alteration was present in 15 adenomas (LOH in 11 and four point mutations). KRAS mutations were detected in 10% of the cases. APC mRNA was overexpressed in adenomas. MYC and AXIN2 were also overexpressed, with significant intra-case heterogeneity. Increased cytoplasmic and/or nuclear beta-catenin staining was seen in 94% and 80% of the adenomas. beta-Catenin nuclear staining was strongly associated with MYC levels (p value 0.03) but not with KRAS mutations. Copy number aberrations were rare. However, the recurrent chromosome changes observed more frequently contained Wnt pathway genes (p value 0.012). Based on beta-catenin staining and Wnt pathway target genes alterations the Wnt pathway appears to be constitutively activated in all APC-FAP tumours, with alterations occurring both upstream and downstream of APC. Wnt aberrations are present at both the DNA and the RNA level. Somatic profiling of APC-FAP tumours provides new insights into the role of APC in tumourigenesis.

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.

Germinated brown rice (GBR) reduces the incidence of aberrant crypt foci with the involvement of beta-catenin and COX-2 in azoxymethane-induced colon cancer in rats

Chemoprevention has become an important area in cancer research due to the failure of current therapeutic modalities. Epidemiological and preclinical studies have demonstrated that nutrition plays a vital role in the etiology of cancer. This study was conducted to determine the chemopreventive effects of germinated brown rice (GBR) in rats induced with colon cancer. GBR is brown rice that has been claimed to be richer in nutrients compared to the common white rice. The male Sprague Dawley rats (6 weeks of age) were randomly divided into 5 groups: (G1) positive control (with colon cancer, unfed with GBR), (G2) fed with 2.5 g/kg of GBR (GBR (g)/weight of rat (kg)), (G3) fed with 5 g/kg of GBR, (G4) fed with 10 g/kg of GBR and (G5) negative control (without colon cancer, unfed with GBR). GBR was administered orally once daily via gavage after injection of 15 mg/kg of body weight of azoxymethane (AOM) once a week for two weeks, intraperitonially. After 8 weeks of treatment, animals were sacrificed and colons were removed. Colonic aberrant crypt foci (ACF) were evaluated histopathologically. Total number of ACF and AC, and multicrypt of ACF, and the expression of beta-catenin and COX-2 reduced significantly (p < 0.05) in all the groups treated with GBR (G2, G3 and G4) compared to the control group (G1). Spearman rank correlation test showed significant positive linear relationship between total beta-catenin and COX-2 score (Spearman's rho = 0.616, p = 0.0001). It is demonstrated that GBR inhibits the development of total number of ACF and AC, and multicrypt of ACF, reduces the expression of beta-catenin and COX-2, and thus can be a promising dietary supplement in prevention of colon cancer.

Optimization of visibility and quantification of aberrant crypt foci in colonic mucosa in Wistar rats

PURPOSE

Test immersion of microscopy samples in water as an aid to visualizing and quantifying aberrant crypt foci (ACF) in rat colon mucosa.

METHODS

Carcinogenesis was induced with azoxymethane in Wistar rats kept on a conventional diet or a hypercaloric diet containing unsaturated fat. Fifteen weeks after induction, colon samples were retrieved and fixated in a 10% formaldehyde solution. The samples were divided into segments (distal, middle, proximal) and stained with 1% toluidine blue. The technique tested in the study consisted of immersing microscopy samples in distilled water in order to eliminate the problem of light reflection known from conventional microscopy.

RESULTS

When samples were immersed in water during microscopy, significantly more ACF could be visualized in all colon segments than with the conventional method proposed by Bird.

CONCLUSION

Immersing microscopy samples in water aids the visualization and quantification of aberrant crypt foci in rat colon mucosa fixed in formaldehyde.

Suppressive effect of sulindac on branch duct-intraductal papillary mucinous neoplasms

BACKGROUND

When considering surgery for branch duct-intraductal papillary mucinous neoplasms (BD-IPMNs) with suspected malignancy, it should be recognized that these lesions are frequently multifocal and are usually found in elderly patients with potential comorbidities that could affect the outcome of surgery. Clinical trials of chemoprevention have been conducted for a wide variety of malignancies.

METHODS

Twenty-two BD-IPMN patients participated in the trial at our institution from June 2004 to January 2007. Ten of the 22 patients who rejected surgical therapy although their lesions or clinical symptoms met the criteria for surgical resection of the International Association of Pancreatology guidelines were assigned to the treatment group. Sulindac (150 mg twice daily) and omeprazole (20 mg once daily) were administered to these patients for 18 months. The remaining 12 patients comprised the control group. Branch duct diameter and mural nodule heights were monitored by either magnetic resonance cholangiopancreatography (MRCP) or computed tomography (CT) and by endoscopic ultrasonography (EUS).

RESULTS

Both branch duct diameter and mural nodule height of BD-IPMNs in the treatment group were significantly reduced, while those in the control group were unchanged. Immunohistochemical staining for cyclooxygenase-1 and -2 was negative in hyperplasia, adenoma and carcinoma portions of resected pancreatic specimens but was clearly positive for glutathione-S-transferase pi (GST-pi), suggesting that GST-pi is a putative target molecule for sulindac.

CONCLUSIONS

Although a larger scale randomized controlled study is needed in future, the present results suggest the promise of chemoprevention of carcinoma derived from BD-IPMNs by sulindac.

Long-term ingestion of reduced glutathione suppressed an accelerating effect of beef tallow diet on colon carcinogenesis in rats

PURPOSE

We have shown previously that long-term feeding of beef tallow increases colorectal cancer in rats. This study investigated the effects of enzymic antioxidant, reduced glutathione (GSH), on colon carcinogenesis in rats fed with beef tallow.

METHODS

Colon carcinogenesis was induced by intraperitoneal injection of azoxymethane (AOM) to rats. Rats were fed with 10% beef tallow supplemented with or without 1% GSH in drinking water. Aberrant crypt foci (ACF) and expression of beta-catenin in colonic mucosa were examined at 12 weeks. Cancers, related substances of oxidative stress and arachidonic acid cascade in plasma and normal colonic mucosa were determined at 44 weeks.

RESULTS

GSH attenuated the number of ACF increased by beef tallow, but GSH had no influence on expression of beta-catenin increased by AOM. Incidence of colon cancer was no different with or without GSH, but GSH attenuated the number of colon cancers in each rat. GSH suppressed plasma malondialdehyde concentration. GSH increased GSH concentration and activities of catalase, glutathione peroxidase and superoxide dismutase in colonic mucosa, and decreased cyclooxygenase-2, prostaglandin E2 and thromboxane B2 levels.

CONCLUSIONS

This study indicated that GSH suppressed the number of ACF, but the attenuation of colon carcinogenesis was limited to the number of colon cancers, although anti-oxidative effects and suppressive effects of arachidonic acid cascade were demonstrated by several indexes. These results suggested that colon carcinogenesis enhanced by beef tallow was partly caused by oxidative stress and arachidonic acid cascade, which were reduced by GSH.

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.

Reliability and accuracy of the endoscopic appearance in the identification of aberrant crypt foci

BACKGROUND

Aberrant crypt foci (ACF) have emerged as a putative precursor to colorectal adenoma, with potential use as a biomarker of colorectal cancer. However, there are wide differences in ACF prevalence, dysplasia, and histologic confirmation rates across studies. These differences may, in part, be because of variability in identification of endoscopic criteria.

OBJECTIVE

To systematically evaluate the accuracy and reliability of various endoscopic criteria used to identify ACF when using magnification chromoendoscopy (MCE).

DESIGN

Images obtained via MCE were shown to participating endoscopists who diagnosed them as ACF or not and who assessed them for the endoscopic characteristics used to identify ACF in the literature.

MAIN OUTCOME MEASUREMENTS

The predictive ability of the endoscopic criteria (crypt number, staining, margin, crypt size, epithelial thickness, and lumen shape) for histologic confirmation of ACF, and their reliability across endoscopists. The accuracy of the examiners in identifying ACF that were histologically confirmed was also assessed.

RESULTS

The interrater agreement rate for all except one of the endoscopic criteria (crypt number) was low and did not improve with training. None of the criteria could significantly predict histologic confirmation of ACF. Despite training exercises, accuracy of endoscopists to correctly identify a histologically proven ACF remained low.

LIMITATIONS

Still images with x40 optical magnification were analyzed rather than real-time endoscopy. All ACF samples were hyperplastic; none were dysplastic.

CONCLUSIONS

No endoscopic criteria evaluated by our study predicted histologic confirmation of ACF. MCE had low accuracy and poor reliability.

Colonic adenoma patients have higher incidence of hyperplastic polyps on surveillance colonoscopy

OBJECTIVES

To determine the incidence of hyperplastic polyps in patients undergoing surveillance colonoscopy and to compare with the prevalence in individuals undergoing index colonoscopy.

PATIENTS AND METHODS

This prospective observational study included patients with index colonoscopy findings of adenomas, adenoma with concomitant hyperplastic polyps and advanced neoplasia who subsequently underwent surveillance colonoscopy. Patient characteristics, indications for colonoscopy, interval between examinations and findings were recorded. These findings were compared with our control group that comprised of patients who underwent index colonoscopy during the same period.

RESULTS

Study group consisted of 108 patients (median age 61.5 years) who underwent index colonoscopy for indications including, weight loss, rectal bleeding, altered bowel habits and anaemia. On index colonoscopy, adenomas, adenoma with concomitant hyperplastic polyps and advanced neoplasia were present in 61, 35 and 12 patients, respectively. Surveillance colonoscopy was performed after a mean follow-up period of 29 +/- 17 months. Findings on surveillance examination included hyperplastic polyps in 35 and 57% of patients with past adenomas and adenoma with concomitant hyperplastic polyps, respectively. Control group included 3852 symptomatic patients who had index colonoscopy (median age, 65 years). Hyperplastic polyps, adenomas and advanced neoplasia were found in 155 (4%), 388 (10%) and 60 (1.5%) of patients, respectively. Hyperplastic polyps and adenoma were significantly higher in study group as compared with control group (P >0.5).

CONCLUSION

Incidence of hyperplastic polyps is significantly higher on surveillance colonoscopy as compared with the prevalence on index colonoscopy. This may signify a continuous spectrum of biological evolution between hyperplastic polyps and adenomas.

Chemoprevention of colorectal cancer-experimental and clinical aspects-

Colorectal cancer is a leading cause of cancer-related mortality worldwide. Therefore, an appropriate prevention strategy should be urgently established. Chemoprevention involves the use of oral agents to suppress the development of cancer. Recent progress in the molecular analysis of colorectal cancer has revealed many candidate molecules for chemoprevention. Many new agents targeting these molecules have also been developed. These agents are largely classified into three categories: 1) Signal transduction modulators including epidermal growth factor (EGF) receptor inhibitors, anti-vascular endothelial growth factor (VEGF) antibodies, and inhibitors of oncogene products. 2) Epigenetic modulators including peroxisome proliferative activated receptor (PPAR)-gamma agonists, estrogen receptor (ER)-beta, and histone deacetylase inhibitors. 3) Anti-inflammatory modulators including cyclooxygenase (COX)-2, EP 1-4, and NF-kB. Of these agents, some actually proceeded to human clinical trials, and have been shown to be active chemopreventive agents.

Nanoscale cellular changes in field carcinogenesis detected by partial wave spectroscopy

Understanding alteration of cell morphology in disease has been hampered by the diffraction-limited resolution of optical microscopy (>200 nm). We recently developed an optical microscopy technique, partial wave spectroscopy (PWS), which is capable of quantifying statistical properties of cell structure at the nanoscale. Here we use PWS to show for the first time the increase in the disorder strength of the nanoscale architecture not only in tumor cells but also in the microscopically normal-appearing cells outside of the tumor. Although genetic and epigenetic alterations have been previously observed in the field of carcinogenesis, these cells were considered morphologically normal. Our data show organ-wide alteration in cell nanoarchitecture. This seems to be a general event in carcinogenesis, which is supported by our data in three types of cancer: colon, pancreatic, and lung. These results have important implications in that PWS can be used as a new method to identify patients harboring malignant or premalignant tumors by interrogating easily accessible tissue sites distant from the location of the lesion.

Endoscopy, morphology, morphometry and molecular markers: predicting cancer risk in colorectal adenoma

The evaluation of short- and long-term risk for developing cancer in patients with colorectal adenomas is controversial. Good, reliable predictors of cancer risk in any adenoma are currently lacking and are limited to adenoma size, number and histologic type. In fact, the evaluation of any adenoma or precancer lesion (e.g., hyperplastic polyps, serrated adenoma or aberrant crypt foci) within the colorectum may be assessed by a number of techniques ranging from direct visualization through the endoscope, to microscopic assessment, and to evaluation at the molecular level. Emerging techniques may yield improved methods of adenoma risk-assessment in the near future. For one, newer endoscopy technologies include chromoendoscopy or endocytoscopy, which now render endoscopists able to resolve the surface and subsurface mucosa at cellular resolution in vivo and in real time - thus, bringing the microscope to the patient's bedside. This new era in endoscopic imaging is dubbed 'histoendoscopy'. Further, while traditional views of classifying protruding and sessile lesions include those of Haggitt, the sm-classification, the Japanese and the so-called Vienna classifications to evaluate neoplasia, the development of new molecular techniques may give way to new methods of classifying preneoplasia and precancerous lesions. This review discusses some pros and cons of risk evaluation technologies in the colorectal tract by endoscopy, microscopy, and quantitative and molecular features. The morphometry-based studies performed over the past decades for the quantitative assessment of cellular and nuclear features within adenomas have failed to yield results amenable for clinical translation and are unlikely to improve further and gain widespread use with current technology. Rather, emerging knowledge of pathway-specific markers through the outlining of a molecular classification will likely be the basis for improved detection and diagnosis. The emerging genomic and proteomic technologies allowing for noninvasive tests to detect (asymptomatic) cancer and neoplasia are discussed. Lastly, the importance of recognizing bias and pitfalls and the adherence to guidelines for biomarker research are addressed.

Anticarcinogenic efficacy of phytic acid extracted from rice bran on azoxymethane-induced colon carcinogenesis in rats

This study is carried out to determine the potential of phytic acid extracted from rice bran in the suppression of colon carcinogenesis induced by azoxymethane (AOM) in rats. Seventy-two male Sprague-Dawley rats were divided into 6 groups with 12 rats in each group. The intended rats for cancer treatment received two intraperitoneal injections of AOM in saline (15mg/kg bodyweight) over a 2-week period. The treatments of phytic acid were given in two concentrations: 0.2% (w/v) and 0.5% (w/v) during the post-initiation phase of carcinogenesis phase via drinking water. The colons of the animals were analyzed for detection and quantification of aberrant crypt foci (ACF) after 8 weeks of treatment. The finding showed treatment with 0.2% (w/v) extract phytic acid (EPA) gave the greatest reduction in the formation of ACF. In addition, phytic acid significantly suppressed the number of ACF in the distal, middle and proximal colon as compared to AOM alone (p<0.05). For the histological classification of ACF, treatment with 0.5% (w/v) commercial phytic acid (CPA) had the highest percentage (71%) of non-dysplastic ACF followed by treatment with 0.2% (w/v) EPA (61%). Administration of phytic acid also reduced the incidence and multiplicity of total tumors even though there were no significant differences between groups. In conclusion, this study found the potential value of phytic acid extracted from rice bran in reducing colon cancer risk in rats.

Simultaneous exposure to dietary acrylamide and corn oil developed carcinogenesis through cell proliferation and inhibition of apoptosis by regulating p53-mediated mitochondria-dependent signaling pathway

To investigate whether simultaneous exposure to acrylamide (ACR) and long-term dietary corn oil induces colon cancer by inhibiting the tumor suppressor gene p53-mediated mitochondria-dependent apoptosis in rats. Male Sprague-Dawley rats were given intraperitoneal injections of ACR at dose of 10 mg/kgbw and diets supplemented with 10% corn oil for 8 wks; and then rats were still fed with diets supplemented with 10% oil for other 48 wks. Colonic aberrant crypt foci (ACF) and tumors, including adenomas and carcinomas, were examined at 12, 24, 36, 48 week post ACR-exposure. Colonic apoptosis and cell proliferation, expression of Wild type (wt) p53, Bcl-2, Bax and caspase-3, were detected at 48 week post ACR-exposure. ACF was found at 12 week and colon cancer invasion was found at 48 week in ACR rats on long-term dietary corn oil. Apoptosis was decreased and cell proliferation was increased in colonic mucosa in ACR-treated rats on dietary corn oil compared to vehicle rats on basal diet ( P < 0.05). In ACR rats on dietary corn oil, mitochondrial wt p53 was significantly inhibited through decreased mitochondrial localization of wt p53 and increased cytosolic p53, resulting in the up-regulation of Bcl-2 and the down-regulation of Bax in the mitochondria, also inhibition of the release of cytochrome-c from the mitochondria into the cytosol and protein level of caspase-3 ( P < 0.05). Results suggest that simultaneous exposure to ACR and long-term dietary corn oil induces development of colon cancer partly by inhibiting the tumor suppressor gene p53-mediated mitochondria-dependent apoptosis.

A multicenter study of prevalence and risk factors for aberrant crypt foci

BACKGROUND & AIMS

Aberrant crypt foci (ACF) are the putative precursor of colorectal adenomas. However, there are limited data available on the prevalence and risk factors for ACF.

METHODS

Subjects from the Prostate, Lung, Colorectal and Ovarian cancer screening trial were recruited for an ACF study, with subjects with adenoma history being oversampled. By using a standardized protocol of magnified chromoendoscopy with methylene blue staining (up to the middle rectal fold), ACF were photo-documented and removed for histologic evaluation.

RESULTS

A total of 505 (66% male; 55% > or =70 y) subjects from 4 institutions were examined; 42% had no adenoma, 32% had nonadvanced distal adenoma, and 25% had advanced distal adenoma at the baseline Prostate, Lung, Colorectal and Ovarian cancer screening trial examination (8.2 years before ACF examination on average). A total of 68% of this population had 1 or more ACF, 43% had 1 to 3, 19% had 4 to 6, and 5% had 7 or more. Baseline adenoma status was not associated with ACF prevalence (range, 66%-69%) or mean number of ACF (range, 3.1-3.5). Of 143 endoscopic ACF examined histologically, 68.5% were confirmed to be ACF. In a logistic model, current (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.2-5.6) and former smoking (OR, 1.6; 95% CI, 1.1-2.5) were associated with higher ACF prevalence; a body mass index greater than 30 was associated with lower prevalence (OR, 0.53; 95% CI, 0.35-0.8). Age, sex, family history of colorectal cancer, and aspirin/nonsteroidal anti-inflammatory drug use were not associated significantly with ACF prevalence.

CONCLUSIONS

ACF prevalence and number were not associated with adenoma history, and only 68.5% of endoscopic ACF were confirmed histologically. These results raise concern about the use of ACF as a surrogate marker of colorectal cancer risk.

Rectal mucosal microvascular blood supply increase is associated with colonic neoplasia

PURPOSE

Endoscopic examination has proven effective in both detecting and preventing colorectal cancer; however, only about a quarter of eligible patients undergo screening. Even if the compliance rate increased, limited endoscopic capacity and cost would be prohibitive. There is a need for an accurate method to target colonoscopy to those most at risk of harboring colonic neoplasia. Exploiting field carcinogenesis seems to be a promising avenue. Our group recently reported that an early increase in blood supply (EIBS) is a reliable marker of field carcinogenesis in experimental models. We now investigate whether in situ detection of EIBS in the rectum can predict neoplasia elsewhere in the colon.

EXPERIMENTAL DESIGN

We developed a novel polarization-gated spectroscopy fiber-optic probe that allows depth-selective interrogation of microvascular blood content. Using the probe, we examined the blood content in vivo from the rectal mucosa of 216 patients undergoing screening colonoscopy.

RESULTS

Microvascular blood content was increased by approximately 50% in the endoscopically normal rectal mucosa of patients harboring advanced adenomas when compared with neoplasia-free patients irrespective of lesion location. Demographic factors and nonneoplastic lesions did not confound this observation. Logistic regression using mucosal oxyhemoglobin concentration and patient age resulted in a sensitivity of 83%, a specificity of 82%, and an area under the receiver operating characteristic curve of 0.88 for the detection of advanced adenomas.

CONCLUSIONS

Increased microvascular blood supply in the normal rectal mucosa is associated with the presence of clinically significant neoplasia elsewhere in the colon, supporting the development of rectal EIBS as a colon cancer risk-stratification tool.

Aberrant crypt foci: endoscopic assessment and cell kinetics characterization

BACKGROUND AND AIMS

Aberrant crypt foci (ACF) are preneoplastic lesions in animal models of colorectal cancer. The aim of the study is to investigate if ACF are involved in human colorectal carcinogenic process and if they can be helpful in predicting the presence of a colorectal neoplasia.

METHODS

The study included, between 2003 and 2005, 182 patients, 62 with adenoma, 55 with colorectal carcinoma, 53 without colorectal lesions, and 12 with nonneoplastic mucosal polyps. The number of rectal ACF was determined by colonoscopy. Proliferation and apoptosis indexes were evaluated by immunohistochemistry in rectal ACF, in normal rectal mucosa, and in carcinomatous tissue.

RESULTS

The mean number of rectal ACF in patients with rectal neoplasia was 12.64, significantly higher than in patients with neoplastic lesions elsewhere in the colon (p=0.01). The apoptosis index in ACF of patients with colorectal carcinoma or adenoma aged 50 years or older was significantly lower than in younger patients (1.3% vs 2.7%, p=0.01) and, in patients with carcinoma, lower than in normal mucosa (1.1% vs 2.1%, p=0.002). The proliferation index was significantly higher in ACF of patients with colorectal neoplasia aged less than 50 years than in normal mucosa (10.9% vs 7.7%, p=0.02). The apoptosis index in ACF foci of patients with carcinoma (1.1%) was significantly lower than in patients without lesions (2.2%) and than in normal mucosa (2%). The mean number of ACF is significantly higher in patients with polyps larger than 1 cm (11.28 vs 6.27, p=0.02).

CONCLUSION

Aberrant crypt foci probably precede the appearance of neoplasia and may be helpful in predicting the presence of a colorectal neoplastic lesion.