Genetic variants in frizzled-related protein (FRZB) and the risk of colorectal neoplasia

Objective  The Wnt/APC/β-catenin signaling pathway, which includes frizzled-related protein (FRZB), plays a critical role in the development of colorectal cancer, and recent evidence suggests that the functional polymorphism, FRZB Arg324Gly, may be associated with risk for this disease. To determine if this finding could be replicated, we investigated the association between two FRZB polymorphisms (Arg324Gly and Arg200Trp) and the risk of colorectal adenoma and cancer in nested case–control studies. Methods  Participants consisted of 1,709 adenoma cases, 620 cancer cases, and 1,849 controls within the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CI) for the associations with colorectal neoplasia. Results  No association was observed for either polymorphism or any haplotypes with colorectal adenoma or colorectal cancer (p > 0.05 for all). Conclusion  Our study does not support the previously observed association between the FRZB 324Gly variant and colorectal cancer risk. However, further study of additional genetic variants within this pathway is still warranted, given the important role of the Wnt signaling pathway in colorectal carcinogenesis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Detection of stool DNA mutations before and after treatment of colorectal neoplasia

BACKGROUND: Whether stool DNA abnormalities arise solely from colorectal neoplastic lesions or are due to more pervasive field effects is not known. In the current study, the authors conducted a prospective multicenter study to evaluate the performance of stool-based DNA testing in a large cohort and to examine whether the findings before treatment persist after surgical resection and/or adjuvant therapy. METHODS: Patients with newly diagnosed colorectal carcinoma or advanced adenomas (AA) provided stool samples before therapy, 1-3 months after surgical resection, and 6-9 months postresection. Stool samples were analyzed using the multi-target DNA assay panel (MTAP) consisting of 23 markers: 21 mutations in the p53, K-ras, and APC genes, a microsatellite instability marker (BAT-26), and the DNA integrity assay (DIA), a marker of loss of apoptosis. RESULTS: Overall, 49 of 91 individuals (54%) tested positive with the MTAP test. The sensitivity of the MTAP test was 63% for invasive tumors compared with 26% for AA. Individuals whose lesions had a more advanced TNM stage or were located distal to the splenic flexure were significantly more likely to have a positive MTAP test. Of the 79 samples collected at 1-3 months after surgical resection of the neoplasm, 14 (18%) had a positive MTAP result, 12 of which were positive for DIA only. Of those collected at 6-9 months of follow-up, 5 of 72 (7%) tested positive on the MTAP panel. CONCLUSIONS: Although many samples collected 1-3 months after surgical resection of the colorectal neoplasm tested positive on the MTAP, most were negative by 6-9 months, indicating that stool DNA abnormalities disappear after treatment of the neoplastic lesions. Surgery and chemoradiation appear to induce transient DIA abnormalities that may be independent of the presence of neoplasia.     

Ornithine decarboxylase levels in the rectal mucosa of patients with colonic neoplasia

Ornithine decarboxylase (ODC) activity in biopsy specimens of normal-appearing rectal mucosa was measured in 15 control patients, 5 patients with colon adenomas, and 11 patients with colon cancer. While women had significantly higher ODC activity than men, ODC activity was increased regardless of gender in the rectal mucosal biopsies of patients with benign or malignant colonic neoplasia compared with those of controls. The positive predictive value of ODC activity for remote colonic neoplasia was 61% for women and 91% for men. The results provide a rationale for long-term studies of ODC activity in rectal mucosa as a biological marker of high risk for large bowel neoplasia.     

EVALUATION OF REVERSE PASSIVE HEMAGGLUTINATION （RPHA） FECAL OCCULT BLOOD TEST IN SCREENING OF COLORECTAL NEOPLASIA

ＥＶＡＬＵＡＴＩＯＮＯＦＲＥＶＥＲＳＥＰＡＳＳＩＶＥＨＥＭＡＧＧＬＵＴＩＮＡＴＩＯＮ（ＲＰＨＡ）ＦＥＣＡＬＯＣＣＵＬＴＢＬＯＯＤＴＥＳＴＩＮＳＣＲＥＥＮＩＮＧＯＦＣＯＬＯＲＥＣＴＡＬＮＥＯＰＬＡＳＩＡＹｕＨａｉ；ＺｈｏｕＬｕｎ；ＺｈｅｎＢｅｉｙｉ；Ｑ...     

An evaluation of rectal epithelial proliferation measurement as biomarker of risk for colorectal neoplasia and response in intervention studies.

Colorectal carcinogenesis is preceded by a phase of epithelial hyperproliferation. Detection and measurement of this hyperproliferation could be useful as a marker of risk for neoplasia or a measure of response to intervention therapy. Today, bromodeoxyuridine labelling and immunohistology is the easiest to perform and most standardized technique for evaluating proliferation in experimental and human studies. In general, measurement of proliferation has fulfilled expectation in experimental studies, however, in humans it has been less conclusive. The reasons are multifactorial and include: limitations in obtaining tissue samples and sampling error, the type of labelling technique used, lack of an objective method for quantifying proliferation and confounding factors influencing the degree of proliferation. The use of matched controls, sophisticated statistical analysis and the search for trends and not just statistical significance, is to be recommended. At present, evaluation of rectal epithelial proliferation is of limited value in assessing risk for colorectal neoplasia in the individual. On the other hand, it seems a useful biomarker of response within the context of a matched control intervention trial.     

Phosphodiesterases in non-neoplastic appearing colonic mucosa from patients with colorectal neoplasia

Background

Intracellular signaling through cyclic nucleotides, both cyclic AMP and cyclic GMP, is altered in colorectal cancer. Accordingly, it is hypothesized that an underlying mechanism for colorectal neoplasia involves altered function of phosphodiesterases (PDEs), which affects cyclic nucleotide degradation. Here we present an approach to evaluate the function of selected cyclic nucleotide-PDEs in colonic endoscopic biopsies from non-neoplastic appearing mucosa.

Methods

Biopsies were obtained from patients with and without colorectal neoplasia. Activities of PDEs were characterized functionally by measurements of transepithelial ion transport and their expression and localization by employing real-time qPCR and immunohistochemistry.

Results

In functional studies PDE subtype-4 displayed lower activity in colorectal neoplasia patients (p?=?0.006). Furthermore, real-time qPCR analysis showed overexpression of subtype PDE4B (p?=?0.002) and subtype PDE5A (p?=?0.02) in colorectal neoplasia patients. Finally, immunohistochemistry for 7 PDE isozymes demonstrated the presence of all 7 isozymes, albeit with weak reactions, and with no differences in localization between colorectal neoplasia and control patients. Of note, quantification of PDE subtype immunostaining revealed a lower amount of PDE3A (p?=?0.04) and a higher amount of PDE4B (p?=?0.02) in samples from colorectal neoplasia patients.

Conclusion

In conclusion, functional data indicated lower activity of PDE4 subtypes while expressional and abundance data indicated a higher expression of PDE4B in patients with colorectal neoplasia. We suggest that cyclic nucleotide-PDE4B is overexpressed as a malfunctioning protein in non-neoplastic appearing colonic mucosa from patients with colorectal neoplasia. If a predisposition of reduced PDE4B activity in colonic mucosa from colorectal neoplasia patients is substantiated further, this subtype could be a potential novel early diagnostic risk marker and may even be a target for future medical preventive treatment of colorectal cancer.

     

Molecular discrimination between alpha-fetoprotein from patients with hepatocellular-carcinoma and nonneoplastic liver-diseases by their carbohydrate structures (review)

Serum alpha-fetoprotein (AFP) is a good marker of HCC. However, this protein also increases moderately in non-neoplastic liver diseases. The serum concentration of AFP in HCC at the time of initial diagnosis has become lower thanks to the advancement of imaging modalities. These clinical circumstances have lead to the need of molecular discrimination of AFP between HCC and benign liver diseases. This has been attained by taking advantage of the reactivity of AFP with various lectins. The relative amount of the Lens culinaris agglutinin (LCA)-reactive species of AFP is significantly greater in HCC than in benign liver diseases. Molecular basis of this variation is the fucosylation of sugar chain at innermost N-acetyl-glucosamine. On the other hand, the concanavalin A (Con A)-nonreactive species of AFP increases in AFP-producing gastrointestinal carcinoma as compared with HCC and benign liver diseases. Molecular basis of Con A-nonreactive variants is the N-acetylglucosaminylation of the mannose residue at the trimannosyl core, although the position to be modified can be different. Therefore, the terms 'fucosylation and glucosaminylation indices' have been introduced to express the percentages of LCA-reactive and Con A-nonreactive species of AFP, respectively. The reactivity of AFP to erythroagglutinating phytohemagglutinin of Phaseolus vulgaris (E-PHA) also provides useful information for discrimination between HCC and benign liver diseases. These indices together with the measurement of E-PHA molecular variants are useful to detect HCC even if the disease is at an early stage. Furthermore, they seem to serve the prediction of HCC in the follow-up course of chronic liver diseases. Thus, not only qualitative but also quantitative measurements of lectin-based molecular variants of AFP provide us valuable information for the differential diagnosis of various liver diseases.     

A novel high-specificity approach for colorectal neoplasia: Detection of K-ras2 oncogene mutation in normal mucosa

There is an important need for a high-specificity approach to colorectal cancer. Approximately 50% of colorectal tumors contain K-ras gene mutations, which occur as an early step in carcinogenesis. K-ras mutations were detectable not only in tumors but also in microscopically normal colorectal mucosa close to carcinomas in some patients with colorectal cancer. This is the first systematic analysis of K-ras mutations in normal colonic mucosa at multiple consistently-selected locations. A total of 480 normal colonic mucosal samples were obtained from 80 subjects, including 65 patients with sporadic colorectal cancer and 15 controls in whom a colorectal neoplasm was ruled out endoscopically. Normal mucosal samples were obtained at multiple consistently-selected locations using biopsy forceps during colonoscopy. Mutant allele-specific amplification (MASA)-PCR was performed; this could detect a K-ras mutation in normal colonic mucosa even though it was only sparsely present. The K-ras mutation was found in histologically normal mucosa from colorectal cancer patients (20 of 65 cases; 41 of 390 loci) by MASA-PCR, especially frequent (51%; 19 of 37 cases) when the tumor showed a K-ras mutation. In contrast, no mutation was found in normal mucosa from 15 controls (90 loci). K-ras mutation in normal mucosa showed a significant association with the presence of colorectal cancer (p = 0.008). The specificity of the MASA-PCR method for colorectal neoplasms was thus 100%. We conclude that detection of K-ras mutations in normal colonic mucosa might serve as a high-specificity approach to colorectal cancer.     

Elevated serum matrix metalloproteinase 9 (MMP-9) concentration predicts the presence of colorectal neoplasia in symptomatic patients

Early detection of polyps or colorectal carcinoma can reduce colorectal carcinoma-associated deaths. Previous studies have demonstrated raised serum levels of matrix metalloproteinase 9 (sMMP-9) in a range of cancers. The aim of this study was to investigate the role of sMMP-9 levels in identifying colorectal neoplasia. Consenting patients donated a blood sample and were assessed by proforma-led history and physical examination. Samples were analysed for sMMP-9 concentration (enzyme-linked immuno-sorbant assay) and compared to final diagnoses. Logistic regression modelling determined independent factors associated with neoplasia. A total of 365 patients were recruited of whom 300 were analysed, including 46 normal controls. A total of 27 significant adenomas and 63 malignancies were identified. The median sMMP-9 concentration was 443 ng ml(-1) (IQR: 219-782; mean: 546). Patients with neoplasia had significantly elevated sMMP-9 levels (P<0.001). Logistic regression modelling identified elevated log(sMMP-9) as the most significant predictor of neoplasia (chi(2)=38.33, P<0.001). Other significant factors were age, sex, smoking history, abdominal pain and weight loss. The model accurately predicted neoplasia in 77.3% of cases. Sensitivity and specificity were 77.9 and 77.1%. sMMP-9 estimation can accurately stratify patient to low- or high-risk cohorts. Serum sampling is a potential means of avoiding unnecessary colonoscopy and reducing patient anxiety, iatrogenic morbidity and mortality, and cost.     

Similarity of the phenotypic patterns associated with BRAF and KRAS mutations in colorectal neoplasia

Activation of the RAS/RAF/extracellular signal-regulated kinase-mitogen-activated protein kinase/extracellular signal-regulated kinase/mitogen-activated protein kinase pathway by RAS mutations is commonly found in human cancers. Recently, we reported that mutation of BRAF provides an alternative route for activation of this signaling pathway and can be found in melanomas, colorectal cancers, and ovarian tumors. Here we perform an extensive characterization of BRAF mutations in a large series of colorectal tumors in various stages of neoplastic transformation. BRAF mutations were found in 11 of 215 (5.1%) colorectal adenocarcinomas, 3 of 108 (2.8%) sporadic adenomas, 1 of 63 (1.6%) adenomas from familial adenomatous polyposis (FAP) patients, and 1 of 3 (33%) hyperplastic polyps. KRAS mutations were detected in 34% of carcinomas, 31% of sporadic adenomas, 9% of FAP adenomas, and no hyperplastic polyps. Eight of 16 BRAF mutations were V599E, the previously described hotspot, and none of these was associated with a KRAS mutation in the same lesion. The remaining eight mutations involve other conserved amino acids in the kinase domain, and 62.5% have a KRAS mutation in the same tumor. Our data suggest that BRAF mutations are, to some extent, biologically similar to RAS mutations in colorectal cancer because both occur at approximately the same stage of the adenoma-carcinoma sequence, both are associated with villous morphology, and both are less common in adenomas from FAP cases. By contrast, colorectal adenocarcinomas with BRAF mutations are associated with early Dukes' tumor stages (P = 0.006) and no such relationship was observed for KRAS mutations. The presence in some colorectal neoplasms of mutations in both BRAF and KRAS suggests that modulation of the RAS-RAF-extracellular signal-regulated kinase-mitogen-activated protein kinase/extracellular signal-regulated kinase/mitogen-activated protein kinase signaling pathway may occur by mutation of multiple components.     

Expression of Bcl-2 and c-ErbB-2 in colorectal neoplasia

Several studies have been demonstrated the value of c-ErbB-2 and Bcl-2 in predicting the biological behaviour of tumors. The aim of this study was to investigate Bcl-2 and c-ErbB-2 expression in colorectal carcinomas and the correlation between their presence and other clinicopathologic parameters. Eighty-six colorectal carcinomas and 17 adenomas were stained with Bcl-2 and c-ErbB-2 immunohistochemically. Staining patterns were assessed semi-quantitatively and correlated with tumor size, Duke s classification, tumor differentiation, mucinous characteristic and anatomic locations. We detected Bcl-2 expression in 10 of 17 adenomas (58.8 %) and 31 of 86 carcinomas (36.04 %). Positive staining in normal mucosa was observed only in the compartment of cryptic cells. However neither the difference in the rates of Bcl-2 positivity in adenoma and carcinoma groups, nor the correlation with other mentioned clinicopathological parameters, were found statistically significant. Bcl-2 expression was found to be significantly high in mucinous carcinomas. Expression of c-ErbB-2 was observed in 12 of 86 (13.95 %) carcinomas. It was not detected in adenomas and normal mucosa. Although the incidence of c-ErbB-2 in nonmucinous carcinoma was higher than that of mucinous carcinoma, this was not significant. In addition we were unable to show any significant relation between c-ErbB-2 expression and other clinicopathologic features. Our result suggest that c-ErbB-2 protein expression in colorectal carcinomas, is not very frequent event. There is no correlation between c-ErbB-2 expression and malignant potential of colorectal carcinomas. Higher expressions of Bcl-2 in adenomas than carcinomas suggest us a possible role of Bcl-2 in early carcinogenesis of colon. However since we were unable to find any significant correlation between Bcl-2 expression and other parameters the impact of this gene on biological behavior is still unclear for us.     

Association of a common polymorphism in the human GH1 gene with colorectal neoplasia

BACKGROUND: Growth hormone (GH) may be associated with the development of colorectal tumors directly and/or indirectly via an increased plasma level of insulin-like growth factor-I (IGF-I), which has been associated with colorectal cancer risk. Because a T-to-A polymorphism in the human GH1 gene at position 1663 is putatively associated with lower levels of GH and IGF-I, we investigated the relationship of this polymorphism to the risk of colorectal neoplasia. METHODS: We analyzed data from two case-control studies conducted in Hawaii: a population-based study of 535 case patients with colorectal adenocarcinoma and 650 control subjects and a sigmoidoscopy screening-based study with 139 case patients with adenoma and 202 control subjects. All subjects were tested for the GH1 polymorphism. Logistic regression was used to adjust for known risk factors. Plasma IGF-I and IGF binding protein-3 (IGFBP-3) levels were measured in a subset of 293 subjects in the adenoma study (135 case patients and 158 control subjects). All statistical tests were two-sided. RESULTS: Adjusted odds ratios (ORs) for colorectal cancer associated with T/T, T/A, and A/A genotypes were 1.00, 0.75 (95% confidence interval [CI] = 0.58 to 0.99), and 0.62 (95% CI = 0.43 to 0.90), respectively (P(trend) =.006). Adjusted ORs for adenoma were 1.00, 0.76 (95% CI = 0.46 to 1.24), and 0.62 (95% CI = 0.31 to 1.22), respectively (P(trend) =.17). Data from both studies consistently showed that the A allele was associated with a lower risk of colorectal neoplasia than the T allele, although the association with adenoma was not statistically significant. These associations were consistently suggested in Caucasians and Native Hawaiians but not in Japanese. The ratio of plasma IGF-I/IGFBP-3 was lower in individuals with the A allele than in individuals with the T allele (P =.01). CONCLUSION: The human T1663A GH1 gene polymorphism, which may confer lower levels of GH and IGF-I, appears to be associated with a decreased risk of colorectal cancer.     

Aspirin in the chemoprevention of colorectal neoplasia: an overview

Considerable evidence supports the effectiveness of aspirin for chemoprevention of colorectal cancer (CRC) in addition to its well-established benefits in the prevention of vascular disease. Epidemiologic studies have consistently observed an inverse association between aspirin use and risk of CRC. A recent pooled analysis of a long-term posttrial follow-up of nearly 14,000 patients from four randomized, cardiovascular disease prevention trials showed that daily aspirin treatment for about five years was associated with a 34% reduction in 20-year CRC mortality. A separate metaanalysis of nearly 3,000 patients with a history of colorectal adenoma or cancer in four randomized adenoma prevention trials showed that aspirin reduced the occurrence of advanced adenomas by 28% and any adenoma by 17%. Aspirin has also been shown to be beneficial in a clinical trial of patients with Lynch syndrome, a hereditary CRC syndrome; in those treated with aspirin for at least two years, there was a 50% or more reduction in the risk of CRC commencing five years after randomization and after aspirin had been discontinued. A few observational studies have shown an increase in survival among patients with CRC who use aspirin. Taken together, these findings strengthen the case for consideration of long-term aspirin use in CRC prevention. Despite these compelling data, there is a lack of consensus about the balance of risks and benefits associated with long-term aspirin use, particularly in low-risk populations. The optimal dose to use for cancer prevention and the precise mechanism underlying aspirin's anticancer effect require further investigation.     

Positive correlation of insulin-like growth factor-II with proliferating cell index in patients with colorectal neoplasia.

BACKGROUND: Insulin-like growth factor-II (IGF-II) stimulates cell proliferation and is considered a potential risk factor for colorectal cancer. Tumor levels of IGF-II seem to positively correlate with colorectal cancer cell proliferation. This investigation examined the association of circulating IGF-II to the proliferating cell index (PCI) of tumor and matched normal mucosa in patients with colorectal neoplasia. METHODS: Circulating IGF-II level (ng/mL) was determined in the peripheral blood plasma by ELISA. The proliferating cells in tumor or matched normal mucosa were immunohistochemically stained using the primary antibody against Ki-67. Computer image analysis was used and PCI was expressed as the percentage of Ki-67-positive cells/total counted cells. RESULTS: Sixty-four patients were evaluated; 45 had colorectal neoplasia (27 males/18 females; mean age, 66.8 +/- 11.8 years) and 19 had hyperplastic polyps (6 males and 13 females; mean age, 58.4 +/- 14.4 years). Among patients with colorectal neoplasia, blood IGF-II levels were positively correlated with PCI in the matched normal mucosa (r = 0.46, P < 0.05) but not in the tumor. In patients with hyperplastic polyps, blood IGF-II levels were not correlated with the PCI in the polyps. Blood IGF-II levels were higher in colorectal cancer patients with Dukes' C/D stage (P < 0.01) or with positive lymph nodes (P < 0.01). CONCLUSION: Circulating IGF-II positively correlated with PCI in normal colonic mucosa of patients with colorectal neoplasia, suggesting that IGF-II may have a role in initiating the carcinogenic pathway by stimulating cell proliferation. Blood IGF-II was increased in advanced colorectal cancer, indicating that it might enhance colorectal cancer progression and be a useful marker of poor prognosis.