Colorectal Precancerous Lesions Research Articles

Epigenetic silencing of monoallelically methylated miRNA loci in precancerous colorectal lesions.

Epigenetic silencing of protein-encoding genes is common in early-stage colorectal tumorigenesis. Less is known about the methylation-mediated silencing of genes encoding microRNAs (miRNAs), which are also important epigenetic modulators of gene expression. Using quantitative PCR, we identified 56 miRNAs that were expressed in normal colorectal mucosa and in HT29 colorectal cancer cells treated with demethylating agents but not in untreated HT29 cells, suggesting that they probably undergo methylation-induced silencing during colorectal tumorigenesis. One of these, miR-195, had recently been reported to be underexpressed in colorectal cancers and to exert tumor-suppressor effects in colorectal cancer cells. We identified the transcription start site (TSS) for primary miRNA (pri-miR)-497/195, the primary precursor that yields miR-195 and another candidate on our list, miR-497, and a single CpG island upstream to the TSS, which controls expression of both miRNAs. Combined bisulfite restriction analysis and bisulfite genomic sequencing studies revealed monoallelic methylation of this island in normal colorectal mucosa (50/50 samples) and full methylation in most colorectal adenomas (38/50; 76%). The hypermethylated precancerous lesions displayed significantly downregulated expression of both miRNAs. Similar methylation patterns were observed at two known imprinted genes, MEG3 and GNAS-AS1, which encode several of the 56 miRNAs on our list. Imprinting at these loci was lost in over half the adenomas (62% at MEG3 and 52% at GNAS-AS1). Copy-number alterations at MEG3, GNAS-AS1 and pri-miR-497/195, which are frequent in colorectal cancers, were less common in adenomas and confined to tumors displaying differential methylation at the involved locus. Our data show that somatically acquired, epigenetic changes at monoallelically methylated regions encoding miRNAs are relatively frequent in sporadic colorectal adenomas and might contribute to the onset and progression of these tumors.

Clinical diagnostic value of (18)F-FDG PET-CT in incidental finding of focal hypermetabolism focus in the colon and rectum

To investigate the value of incidental focal (18)F-FDG uptake in the colon and rectum and characteristics of functional anatomic form for differential diagnosis of colorectal benign or malignant diseases. Clinical data and images of incidental focal hypermetabolism focus in colon and rectum of 37 individuals undergoing (18)F-FDG PET-CT were analyzed retrospectively. According to the eventual outcomes of pathological examination and clinical follow-up, these cases were divided into four subgroups: malignant disease, benign tumor (including precancerous change), inflammation and physiological uptake. Radioactive uptake level (SUVmax) and change of delayed imaging (RI) of focal hypermetabolism focus were compared between groups. The data analysis was performed using variance analysis. The average SUVmax was 6.3±3.7, 8.8±6.5, 5.2±1.4, and 3.8±0.9 in malignant disease (n=11), benign (precancerous) tumor (n=9), inflammation (n=9) and physiological uptaking (n=8) respectively. The average SUVmax was 7.6±5.6 in benign and malignant tumor, and 4.7±1.5 in inflammation and physiological uptake. The distinction of average SUVmax was not statistically significant between benign and malignant tumor or inflammation and physiological uptake. But it was higher in tumors as compared to inflammation or physiological uptake with a statistically difference (P<0.05). The RI was 0.3±0.2, 0.4±0.1, 0.3±0.2, 0.4±0.2 in above 4 groups respectively, and the differences were not statistically significant. The incidental focal hypermetabolism focus in the colon the rectum during (18)F-FDG PET-CT may indicate potential colorectal malignant diseases and precancerous lesions. SUVmax value in focal hypermetabolism focus in the colon and rectum can help to distinguish tumor from inflammation or physiological uptake. But there is no diagnostic value for distinguishing malignant disease from benign tumor.

Präkanzerosen im Kolon

Preneoplastic lesions of colorectal carcinoma can be divided in non-serrated and serrated lesions. Non-serrated lesions include conventional adenomas (tubular, tubulovillous and villous) and dysplasias associated with inflammatory bowel disease like flat intraepithelial neoplasia, dysplasia-associated lesions or masses (DALM) and adenoma-like masses (ALM). Conventional adenomas are mostly sporadic, but also found in hereditary adenomatous-polyposis syndromes. Hamartous polyposis syndromes are also associated with colorectal cancer. Serrated lesions include hyperplastic polyps, sessile serrated adenomas and traditional serrated adenomas. Based on these precancerous colorectal lesions different molecular subtypes were identified. Histological subtype, size and grade of dysplasia of polyps are essential for risk assessment of colorectal cancer.

Serum-Based DNA Methylation Biomarkers in Colorectal Cancer: Potential for Screening and Early Detection

Colorectal cancer (CRC) is the third most common cause of cancer-related death in the United States. Early identification and treatment of pre-cancerous colorectal lesions, or node-negative CRC are highly effective interventions that substantially reduce disease-specific mortality. Colonoscopy remains a highly effective primary screening tool based on its excellent diagnostic accuracy, and its ability to remove pre-cancerous lesions. However, the nature of the procedure limits compliance with colonoscopy intended for population-based CRC screening. A significant advance in the screening and care of these patients could be realized by blood-based biomarkers, which could accurately identify patients at-risk for CRC development whom might benefit from early and/or more frequent surveillance for disease. We reviewed and herein discuss the potential for serum based DNA methylation biomarkers for screening and early detection of CRC.

Molecular pathways undergoing dramatic transcriptomic changes during tumor development in the human colon

BackgroundThe malignant transformation of precancerous colorectal lesions involves progressive alterations at both the molecular and morphologic levels, the latter consisting of increases in size and in the degree of cellular atypia. Analyzing preinvasive tumors of different sizes can therefore shed light on the sequence of these alterations.MethodsWe used a molecular pathway-based approach to analyze transcriptomic profiles of 59 colorectal tumors representing early and late preinvasive stages and the invasive stage of tumorigenesis. Random set analysis was used to identify biological pathways enriched for genes differentially regulated in tumors (compared with 59 samples of normal mucosa).ResultsOf the 880 canonical pathways we investigated, 112 displayed significant tumor-related upregulation or downregulation at one or more stages of tumorigenesis. This allowed us to distinguish between pathways whose dysregulation is probably necessary throughout tumorigenesis and those whose involvement specifically drives progression from one stage to the next. We were also able to pinpoint specific changes within each gene set that seem to play key roles at each transition. The early preinvasive stage was characterized by cell-cycle checkpoint activation triggered by DNA replication stress and dramatic downregulation of basic transmembrane signaling processes that maintain epithelial/stromal homeostasis in the normal mucosa. In late preinvasive lesions, there was also downregulation of signal transduction pathways (e.g., those mediated by G proteins and nuclear hormone receptors) involved in cell differentiation and upregulation of pathways governing nuclear envelope dynamics and the G2>M transition in the cell cycle. The main features of the invasive stage were activation of the G1>S transition in the cell cycle, upregulated expression of tumor-promoting microenvironmental factors, and profound dysregulation of metabolic pathways (e.g., increased aerobic glycolysis, downregulation of pathways that metabolize drugs and xenobiotics).ConclusionsOur analysis revealed specific pathways whose dysregulation might play a role in each transition of the transformation process. This is the first study in which such an approach has been used to gain further insights into colorectal tumorigenesis. Therefore, these data provide a launchpad for further exploration of the molecular characterization of colorectal tumorigenesis using systems biology approaches.

Metabonomic Variations Associated with AOM-Induced Precancerous Colorectal Lesions and Resveratrol Treatment

Resveratrol (Res), 3,5,4'-trihydroxy-trans-stilbene, is an antioxidant found in the skin of red grapes and in several other plants. This phenolic compound has been recently reported to possess cancer chemopreventive activity that inhibits the process of carcinogenesis. However, the mechanisms underlying its anticancer effects remain largely unresolved. In this study, we investigated the chemoprotective effects of dietary Res in an azoxymethane (AOM) induced precancerous colorectal lesion model in male Wistar rats. The metabolic alterations in urine, sera, and colonic tissues of experimental rats perturbed by AOM intervention as well as the Res treatment were measured by a gas chromatography time-of-flight mass spectrometry (GC-TOFMS) analysis. Significant alterations of metabolites were observed in AOM group in urine, sera, and colonic tissues, which were attenuated by Res treatment and concurrent with the histopathological improvement with significantly decreased aberrant crypt foci (ACF) incidence. Representative metabolites include depleted glucose, β-hydroxybutyrate (ketone body), hypoxanthine, and elevated branched chain amino acids (isoleucine and valine) and tryptophan in colonic tissue, as well as elevated serum aminooxyacetate and urinary 4-hydroxyphenylacetate and xanthurenate. These metabolic changes suggest that the preventive effect of Res is associated with attenuation of impaired glucose and lipid metabolism and elevated protein breakdown in colonic tissues from AOM-exposed rats. It also appears that Res induced significant metabolic alterations independent of the AOM-induced metabolic changes. The significantly altered metabolites identified in Res-AOM group relative to AOM group include arachidonate, linoleate, glutamate, docosahexaenoate, palmitelaidate, 2-aminobutyrate, pyroglutamate, and threonate, all of which are involved in inflammation and oxidation processes. This suggests that Res exerts the chemopreventive effects on ACF formation by anti-inflammatory and antioxidant mechanisms in addition to amelioration of AOM-induced mitochondrial disruption.

Human stool vimentin, oncostatin M receptor and tissue factor pathway inhibitor 2 gene methylation analysis for the detection of colorectal neoplasms

To explore the feasibility of detecting vimentin, oncostatin M receptor (OMSR) and tissue factor pathway inhibitor 2 (TFPI2) gene methylation status in stool samples as a noninvasive screening tool for colorectal cancer and precancerous lesions. Stool samples were collected from 60 patients with colorectal cancer, 17 patients with adenoma and 30 normal volunteers. And fecal DNA was extracted and vimentin, OMSR and TFPI2 gene methylation status was analyzed by methylation-specific polymerase chain reaction (MSP). The methylated vimentin, OMSR and TFPI2 was detected in 53.3% (32/60), 68.3% (41/60) and 75.0% (45/60) of colorectal cancer, and 5, 7 and 11 cases of colorectal adenoma respectively. The sensitivities of combined study, using three markers for the detection of colorectal cancer and colorectal adenomas, were 86.7% (26/30) and 76.5% (13/17) respectively. And the specificity was 86.7% (52/60). As a feasible epigenetic marker, promoter hypermethylation for vimentin, OMSR and TFPI2 in stool samples is a sensitive, specific and noninvasive alternative for colorectal cancer screening.

Prognostic Significance of PKC-ζ and Cortactin Expression in Colorectal Carcinoma

Objective To investigate the relationship between in colorectal cancer,precancerous lesions(adenomatous polyps),and normal tissues and analyze the prognostic impact of PKC-ζ and Cortactin in colorectal cancer. Methods The expressions of PKC-ζ and Cortactin were examined by SP immunohistochemistry in colorectal cancer,colorectal adenomas and colorectal tissues adjacent to adenocarcinomas(normal tissues).Results(1)The positive rates of PKC-ζ and Cortactin in colorectal cancer tissues were significantly higher than those of colorectal tissue adjacent to adenocarcinomas(normal tissues) and colorectal adenomas(P0.05).(2)There was a significant correlation between PKC-ζ and Cortactin expression and tumor cell differentiation,invasive depth,lymph node metastasis and TNM stage(P0.05),but no statistically correlation between PKC-ζ and Cortactin expression and the age,gender,localization of tumor,tumor size and histological types(P0.05).(3)There was a positive correlation between PKC-ζ and Cortactin(r=0.574,P0.05).Conclusion PKC-ζ and Cortactin might be valuable markers in predicting the prognosis of the colorectal cancer and molecule targets for therapy.The combined detection of the PKC-ζ and Cortactin might be a more appropriate method to identify invasion and metastasis and predict the prognosis of colorectal cancer.

The Cooperative Italian FLIN Study Group: prevalence and clinico-pathological features of colorectal laterally spreading tumors

Laterally spreading tumors (LSTs) are increasingly recognized as important precursors of colorectal carcinoma. The clinical behavior of these large nonpolypoid lesions is still uncertain. The aim of the present study was to assess prevalence and clinico-pathological features of LSTs in a large Italian cohort of patients. The study was a subgroup analysis of a large database of patients undergoing total colonoscopy. The database originated from a multicenter cross-sectional observational study involving 80 centers throughout Italy. Data from 27,400 total colonoscopies were analyzed. Precancerous lesions were detected in 5609 patients. Of these, LSTs were identified in 254 patients (4.5%; 95% confidence interval [CI] 3.5-6.2). Granular-type LSTs (G-LSTs) accounted for 83% of the cases (211/254). LSTs were predominant in the proximal colon (154, 60.6%). A total 231 lesions were endoscopically removed, with histology being available for 242. Neoplasia was confirmed in 225 lesions (93.4%) (143 low grade adenoma, 76 high grade adenoma, and six submucosal cancer). The six cases of submucosally invasive carcinoma were diagnosed in five G-LST and one nongranular LST (NG-LST). The risk of containing advanced histology was not increased in G-LST compared with NG-LST (odds ratio [OR] 1.55, 95%CI 0.73-3.27); it was significantly higher in lesions with large nodules (OR 3.09, 95%CI 1.05-9.04; P = 0.041) or depressed surface (OR 4.27, 95%CI 1.24-14.61; P = 0.021). LSTs represent approximately 5% of all precancerous colorectal lesions in the Italian population and are prevalent in the proximal colon. These lesions are no more likely to harbor advanced histology than similar-sized polypoid lesions. Large nodularity or depressed surface are risk factors for advanced histology.

Mutational Hotspots in the Mitochondrial D-Loop Region of Cancerous and Precancerous Colorectal Lesions in Egyptian Patients

Mutations in the mitochondrial genome (mtDNA) are associated with different types of cancer, specifically colorectal cancer (CRC). However, few studies have been performed on precancerous lesions, such as ulcerative colitis (UC) lesions and adenomatous polyps (AP). The aim of this study was to identify mtDNA mutations in the cancerous and precancerous lesions of Egyptian patients. An analysis of the mutations found in six regions of the mtDNA genome (ND1, ND5, COI, tRNAser, D-loop 1, and 2) in 80 Egyptian patients (40 CRC, 20 UC, and 20 AP) was performed using polymerase chain reaction-single-strand conformational polymorphism techniques and followed up by direct sequencing. The overall incidence of mutations was 25%, 25%, and 35% in CRC, UC, and AP cases, respectively. Although there was no common mutation pattern within each group, a large number of mutations were detected in the D-loop region in all of the groups. Some mutations (e.g., T414G) were detected repeatedly in precancerous (UC and AP) and cancerous lesions. Mutations detected in patients with CRC were predominantly found in the ND1 gene (40%). Our preliminary study suggests that Egyptian patients with CRC have a large number of mtDNA mutations, especially in the D-loop region, which have not been previously reported. Mutations in the mtDNA of precancerous lesions (i.e., AP and UC) may contribute to transformation events that lead to CRC.

Preinvasive colorectal lesion transcriptomes correlate with endoscopic morphology (polypoid vs. nonpolypoid)

Improved colonoscopy is revealing precancerous lesions that were frequently missed in the past, and ∼30% of those detected today have nonpolypoid morphologies ranging from slightly raised to depressed. To characterize these lesions molecularly, we assessed transcription of 23,768 genes in 42 precancerous lesions (25 slightly elevated nonpolypoid and 17 pedunculated polypoid), each with corresponding samples of normal mucosa. Nonpolypoid versus polypoid morphology explained most gene expression variance among samples; histology, size, and degree of dysplasia were also linked to specific patterns. Expression changes in polypoid lesions frequently affected cell-cycling pathways, whereas cell-survival dysregulation predominated in nonpolypoid lesions. The latter also displayed fewer and less dramatic expression changes than polypoid lesions. Paradigmatic of this trend was progressive loss through the normal > nonpolypoid > polypoid > cancer sequence of TMIGD1 mRNA and protein. This finding, along with TMIGD1 protein expression patterns in tissues and cell lines, suggests that TMIGD1 might be associated with intestinal-cell differentiation. We conclude that molecular dysregulation in slightly elevated, nonpolypoid, precancerous colorectal lesions may be somewhat less severe than that observed in classic adenomatous polyps.

A New and Highly Sensitive Screening Tool for Colorectal Adenomatous Polyps Using a Spot Urine Metabolomics Test

• Colorectal cancer (CRC) is a major public health concern • Adenomatous polyps are precursors of CRC and their identification is the basis for population-based CRC screening programs • Current world-wide population-based screening uses guaiac-based fecal occult blood tests (FOBT) which has a sensitivity of 5-30% for adenomatous polyps • Newer fecal immunochemical tests (FITs) use antibodies directed against human globin and have a sensitivity of 20-67% for colonic adenomas • Urine metabolomics has the potential to be a more accurate and patient-friendly screening test for colorectal cancer and precancerous lesions.

Pit pattern classification for diagnosis of early colorectal cancers and precancerous lesions

Objective To evaluate pit pattern analysis for detection of early colorectal carcinoma and precancerous lesions. Methods A total of 162 lesions in 144 patients were examined with magnifying colonoscopy after staining, and their pit patter was analyzed with morphology and pathologic diagnosis. Results With confirmation of pathology, there were 34 non-neoplastic lesions and 128 neoplastic ones, in which 12 were carcinomas. The pit patterns in most non-neoplastic lesions （76. 5%, 26/34） were type Ⅰ or Ⅱ , and those in most neoplastic lesions （96. 1% , 123/128） was type Ⅲ, Ⅳ or Ⅴ. Pit patterns of cancerous lesions were mainly type Ⅴ （75.0%, 9/12）, and those of 3 cases of advanced cancers were all type Ⅴ N. Conclusion Pit pattern classification is a very important tool to differentiate between neoplastic, nonneoplastic lesions and early cancer, which helps to decide later therapeutic intervention. Key words: Endoscopy,digestive system; Intestinal neoplasms; Pit pattern; Staining

Performance of Epigenetic Markers SEPT9 and ALX4 in Plasma for Detection of Colorectal Precancerous Lesions

BackgroundScreening for colorectal cancer (CRC) has shown to reduce cancer-related mortality, however, acceptance and compliance to current programmes are poor. Developing new, more acceptable non-invasive tests for the detection of cancerous and precancerous colorectal lesions would not only allow preselection of individuals for colonoscopy, but may also prevent cancer by removal of precancerous lesions.MethodsPlasma from 128 individuals (cohort I – exploratory study: 73 cases / 55 controls ) was used to test the performance of a single marker, SEPT9, using a real-time quantitative PCR assay. To validate performance of SEPT9, plasma of 76 individuals (cohort II – validation study: 54 cases / 22 controls) was assessed. Additionally, improvement of predictive capability considering SEPT9 and additionally ALX4 methylation was investigated within these patients.ResultsIn both cohorts combined, methylation of SEPT9 was observed in 9% of controls (3/33), 29% of patients with colorectal precancerous lesions (27/94) and 73% of colorectal cancer patients (24/33). The presence of both SEPT9 and ALX4 markers was analysed in cohort II and was observed in 5% of controls (1/22) and 37% of patients with polyps (18/49). Interestingly, also 3/5 (60%) patients with colorectal cancer were tested positive by the two marker panel in plasma.ConclusionsWhile these data confirm the detection rate of SEPT9 as a biomarker for colorectal cancer, they also show that methylated DNA from advanced precancerous colorectal lesions can be detected using a panel of two DNA methylation markers, ALX4 and SEPT9. If confirmed in larger studies these data indicate that screening for colorectal precancerous lesions with a blood-based test may be as feasible as screening for invasive cancer.

Effects of cyclooxygenase-2 and proliferating cell nuclear antigen on the onset and development of familial adenomatous polyposis

Long-term use of cyclooxygenase-2 (COX-2) inhibitors can reduce the incidence of digestive cancers, such as colorectal cancers. Proliferating cell nuclear antigen (PCNA) is an important marker of cellular abnormal proliferation. This study was to evaluate the roles and correlation of COX-2 and PCNA in the onset and development of familial adenomatous polyposis (FAP) diseases. Thirty-six specimens of FAP adenomas tissues and 32 specimens of FAP carcinoma tissues from 11 FAP families, and 34 specimens of normal colonic mucosa were collected under colonoscopy from November 2004 to July 2007 in the General Hospital of Beijing Military Command. Immunohistochemistry was used to detect the expressions of COX-2 and PCNA. The positive expression rates of COX-2 in normal colonic mucosa, FAP adenoma, and carcinoma tissues were 0 (0/34), 80.6% (29/36), and 93.8% (30/32), respectively. Proliferation index (PI) in normal mucosa, FAP adenoma, and carcinoma tissues were 17.79+/-7.49, 34.47+/-10.57, and 71.75+/-9.22, respectively. Expressions of COX-2 and PCNA were significantly higher in the FAP adenoma and the carcinoma tissues than in the normal colonic mucosa(P<0.01). The expression of PCNA was significantly higher in the FAP carcinoma tissues than in the FAP adenoma (P<0.01). The expression of PCNA was higher in the FAP adenoma tissues with positive COX-2 than in the FAP adenomas tissues with negative COX-2 (P<0.01). COX-2 may play an important role in the development of FAP adenomas and colorectal carcinogenesis. COX-2 and PCNA may be important factors in the research on colorectal precancerous lesions and interventional therapy for colorectal neoplasm.

ER-β expression in large bowel adenomas: Implications in colon carcinogenesis

Background A pivotal role of oestrogen receptor-beta has been suggested in colon carcinogenesis in humans. However, few data are available on oestrogen receptor-beta in colorectal pre-cancerous lesions. Aim In the present study, we evaluated oestrogen receptor-beta expression and its possible correlation with proliferative activity and apoptosis in colorectal adenomas and normal colon tissue. Patients/methods Adenomatous tissue from 25 patients with colonic polyps, and normal tissue from 25 controls were used. Oestrogen receptor-beta expression, colonocyte proliferation (expressed as PCNA positivity) and apoptosis were evaluated. Results In adenomatous tissue, a significant reduction of oestrogen receptor-beta was observed compared to normal mucosa (10.1 ± 5.5% vs. 44.2 ± 13.7; p < 0.03), while the expression of oestrogen receptor-alpha remained unvaried. Cell proliferative activity significantly increased in adenomatous tissue compared to normal mucosa (59.3 ± 7.1 vs. 18.5 ± 8.8; p < 0.0001), doubling the PCNA/apoptosis ratio. An inverse correlation was found between oestrogen receptor-beta and PCNA expression in adenomas ( r = −0.81), a datum confirmed by confocal microscopy evaluation. Conclusions Our data demonstrate, for the first time, a significant reduction of oestrogen receptor-beta expression already in the pre-cancerous phase of colon carcinogenesis. This suggests a role of selective oestrogen receptor-beta agonists in the prevention of colorectal cancer.

Tissue carcinoembryonic antigen and dna aneuploidy in precancerous and cancerous colorectal lesions

Chronic inflammatory bowel disease (CIBD) and colorectal adenoma are considered as precancerous conditions and lesions of large bowel carcinoma, respectively. They, therefore, may be used to study the behavior of such different factors as tumor-associated antigens and nuclear DNA content abnormalities in colorectal carcinogenesis. Tissue concentrations of carcinoembryonic antigen (CEA) were significantly higher in those precancerous lesions (CIBD: 61 +/- 11.2 ng/mg, adenoma: 70 +/- 6 ng/mg; mean +/- standard error of the mean) than in normal colonic mucosa (36 +/- 4.7 ng/mg). Colorectal carcinoma had still higher tissue levels (437 +/- 108.2 ng/mg). No correlation between tissue CEA and tumor differentiation could be found, but there was a significant difference between aneuploid (747 +/- 354 ng/mg) and diploid (139 +/- 43 ng/mg) tumors. Using flow cytometry DNA aneuploidy was present in 31.6%, 10.5%, and 51.6% of CIBD, colorectal adenoma, and carcinoma, respectively. These data suggest that the occurrence of aneuploidy is not strongly dependent on a malignant transformation, but it may also be present in premalignant colorectal lesions without cellular dysplasia.