Abnormalities of lectin histochemistry in familial polyposis coli and hereditary nonpolyposis colorectal cancer

Colonic carcinogenesis along different genetic routes: glycophenotyping of tumor cases separated by microsatellite instability/stability

Different genetic routes account for colonic carcinogenesis. However, when analyzing colon cancer specimens, separation into different groups based on genetic alterations is commonly not performed. Thus, we here initiate the comparative phenotyping considering microsatellite instability/stability for clinical specimens. The focus is given to glycan epitopes, expression of which is known to be modulated by signal-transducing proteins that act as key regulators of normal colon epithelial growth and differentiation. In addition to six plant lectins used as sensors, the presence of two adhesion/growth-regulatory galectins is studied. Overall, a considerable level of intra- and interindividual heterogeneity is revealed. Alterations in the proportion of stained cells between tumor-adjacent and malignant epithelia concerned plant lectins, which bind substituted N-glycan cores, α2,6-sialylated branch ends, core 1 O-glycans and N-acetylgalactosamine. A tendency for changes was noted between microsatellite-unstable and microsatellite-stable cases for core substitution (bisected N-glycan, presence of β1,6-branching) and status of α2,6-sialylation. Statistical significance was reached for presence of galectin-3, found to be elevated in microsatellite-stable compared to microsatellite-unstable tumors. These results emphasize the potential of distinct signaling pathways to regulate certain aspects of the glycophenotype in vivo and thus delineate a perspective to discern functionally relevant deviations in expression of endogenous lectins and their counter-receptors.

Evolution of the nomenclature for the hereditary colorectal cancer syndromes

The hereditary forms of colorectal cancer have been given many names historically as the manifestations have been gradually understood. Lynch syndrome has had several names, most prominently 'Hereditary Nonpolyposis Colorectal Cancer' or HNPCC. Clarification of the genetic basis and full phenotypic expression of this disease mandates a more clinically useful name that clarifies the consideration of non-colonic cancers in a family history, and unifies the diagnosis around the germline mutation in a DNA mismatch repair (MMR) gene. The term 'Lynch syndrome' is proposed for the autosomal dominant disease caused by a germline mutation in a DNA MMR gene.

Spectral markers in preneoplastic intestinal mucosa: an accurate predictor of tumor risk in the MIN mouse

BACKGROUND

We have reported recently that microarchitectural analysis of the histologically normal mucosa using a novel optics technology, four-dimensional elastic light scattering fingerprinting (ELF), provided unprecedented sensitivity for early detection of colon carcinogenesis. In the present study, we explored the ability of four-dimensional ELF to identify an inherited predisposition to colorectal cancer, an issue of considerable importance for optimizing population screening strategies.

METHODS

We used the MIN mouse, a model whose germ line adenomatous polyposis coli truncation leads to spontaneous intestinal tumorigenesis, thus replicating the human syndrome, familial adenomatous polyposis. Spectral markers were assessed by four-dimensional ELF analysis in MIN mice at preneoplastic time points and compared with age-matched controls (C57BL6 mice with wild-type adenomatous polyposis coli). To assess the responsiveness of spectral markers to chemopreventive agents, a subset of MIN mice was supplemented with celecoxib 1,500 ppm.

RESULTS

Spectral slope, fractal dimension, and principal component 3 were dramatically altered in the uninvolved MIN mouse mucosa at the earliest time points. Furthermore, alteration in spectral variables increased over time, consonant with the microarchitectural underpinnings of subsequent tumorigenesis. Additionally, these markers spatially correlated with future adenoma development (small intestine > colon). Short-term treatment with the potent chemopreventive agent, celecoxib, resulted in near normalization of fractal dimension and principal component 3.

CONCLUSIONS

We report, for the first time, that spectral markers, assayed by four-dimensional ELF, were able to sensitively identify a genetic predisposition for intestinal tumorigenesis before the occurrence of phenotypic manifestations. Moreover, the reversal of spectral markers by celecoxib treatment supports the neoplastic relevance.

Differential expression of sialic acid and N-acetylgalactosamine residues on the cell surface of intestinal epithelial cells according to normal or metastatic potential

In this study we investigated the levels of expression of sialic acid and N-acetylgalactosamine residues on the cell surface of a normal intestinal epithelium cell line, IEC-6, and in two colon adenocarcinoma cell lines with different metastatic potential, Caco-2 and HCT-116. Glycoprotein expression was estimated initially by cytochemistry with WGA and HPA lectins and biochemistry with isolated plasma membrane fractions of the cells. Fluorescence and electron microscopic analyses revealed differences in the expression profile of carbohydrates recognized by the lectins used on the cell surface of IEC-6, Caco-2, and HCT-116 cells. Lectin blotting identified a range of eight HPA-binding glycoprotein bands with molecular weights of 16-66 kD in Caco-2 cells, six glycoproteins of 16-36 kD, and three protein bands of 35, 24, and 21 kD in IEC-6 cells. A minor band of 66 kD and a major one of 50 kD for WGA-binding glycoproteins were observed in IEC-6 cells and seven glycoproteins of 18-97 kD in Caco-2 and HCT-116 cells but with a visible higher expression of these glycoproteins in the latter. Furthermore, significant quantitative difference in levels of expression of WGA- but not of HPA-binding glycoconjugates was noted, as analyzed by high-resolution scanning electron microscopy using backscattered electron images of cells incubated with gold-labeled lectins.

Effects of low dose aspirin (81 mg) on proliferating cell nuclear antigen and Amaranthus caudatus labeling in normal-risk and high-risk human subjects for colorectal cancer

Epidemiological, experimental, and clinical observations provide support for a colorectal cancer chemopreventive role for aspirin. We have evaluated the effects of aspirin on proliferation biomarkers in normal-risk and high-risk human subjects for colorectal cancer. Colorectal biopsies were obtained at baseline and at 24h after 28 daily doses of 81 mg of aspirin from 13 high-risk and 15 normal-risk subjects for colorectal cancer. We evaluated aspirin's effects on proliferating cell nuclear antigen (PCNA) immunohistochemistry and epithelial mucin histochemistry using the lectin, Amaranthus caudatus agglutinin (ACA) in crypt sections from rectal biopsies. The baseline whole crypt PCNA LIs differed significantly between normal-risk and high-risk subjects. PCNA LIs are not affected by 28 days of aspirin at 81 mg daily. ACA LIs are decreased by 28 days of aspirin at 81 mg daily in both normal-risk and high-risk subjects. Aspirin's effects on ACA LIs may have mechanistic and biological implications that deserve further attention. PCNA and ACA LIs are not useful as proliferation biomarkers for aspirin's chemopreventive activity in morphologically normal human colorectal mucosa.

Lectin histochemistry as a predictor of dysplasia grade in colorectal adenomas

Lectins are sugar-binding proteins that bind to specific cellular carbohydrates, commonly affecting cellular physiology. Phaseolus vulgaris leucoagglutinin (PHA), ulex europaeus isoagglutinin-I (UEA-I), wheat germ agglutinin (WGA) and peanut agglutinin (PNA) are among the most well studied lectins in various tissues. The purpose of this study was to detect the above lectins binding sites and so examine alterations in glycoconjugate expression in neoplastic cells of 52 colorectal adenomas with various clinicopathologic characteristics and proliferation rates. Lectin histochemistry was performed in paraffin sections with and without neuraminidase treatment. Proliferative fraction was determined by immunolabelling for Proliferating Cell Nuclear Antigen. PHA was the more frequently positive lectin in the examined specimens; however, it was simultaneously detected in normal colonic mucosa and so was WGA. The frequency of high grade dysplasia was significantly greater in older patients and in samples with UEA-I positivity without neuraminidase pretreatment. UEA-I-reactive adenomas were generally characterized by high cell proliferation rates. A statistical model based on patients age and UEA-I binding without neuraminidase treatment can generally predict grade of dysplasia in 83% of adenomas and particularly high grade dysplasia in up to 93% of adenomas; so, such a model may be potentially useful for the early detection of neoplasia, for instance in exfoliative cells from the large intestine.

Hereditary non-polyposis colorectal cancer: an updated review

INTRODUCTION

Colorectal cancer is the commonest cause of death due to malignancy in non-smokers in the western countries. The two main hereditary types of colorectal cancer are familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC), constituting approximately 10% of all cases of colorectal cancer. The main aim of this review is to reappraise the current advances in the genetics and diagnosis of HNPCC.

METHODS

A Medline search was carried out to identify papers published from 1970 to 1999 on HNPCC. Embase and Cochrane databases were also searched. Reference lists of retrieved articles were carefully searched for additional articles.

RESULTS AND CONCLUSIONS

Recent technological advances in the genetics of HNPCC have refined the criteria for diagnosis and management of HNPCC, however current policies regarding the testing of pedigrees are not clearly established. We believe that with the rapid development in this area definitive clinical guidelines will need to be available in future for the management of HNPCC.

Phytic acid in wheat bran affects colon morphology, cell differentiation and apoptosis

Wheat bran (WB) and its component phytic acid (PA) have both been shown to decrease early biomarkers of colon carcinogenesis, i.e. the PCNA labeling index of cell proliferation and certain aberrant crypt foci parameters. However, it is not known how WB and PA alter other biomarkers of colon cancer risk, such as rate of apoptosis and degree of differentiation, or how they affect colon morphology. Thus, the objectives of this study were to determine the effects of WB on these parameters, to see if PA contributes to these effects and whether there is a difference between endogenous and exogenously added PA. Five groups of azoxymethane-treated male Fischer 344 rats were fed a basal control diet (BD) or BD supplemented with either 25% wheat bran, 25% dephytinized wheat bran (DWB), 25% DWB plus 1.0% PA or 1.0% PA for 100 days. The WB, DWB and PA diets significantly increased the rate of apoptosis and cell differentiation in the whole crypt and the top 40% of the crypt. The WB, DWB and PA diets also significantly increased cell apoptosis in the bottom 60% of the crypt, while all the treatment groups significantly increased cell differentiation versus the BD group in the bottom 60% of the crypt. In addition, the WB, DWB and PA diets decreased the number of crypts per millimeter of colon, while the DWB and PA diets also decreased crypt height measured as number of cells. It is concluded that WB, partly due to its dietary fiber and endogenous PA, and exogenous PA when added to a low fiber diet can increase cell apoptosis and differentiation and favorably affect colon morphology.

Tumor burden and clonality in multiple intestinal neoplasia mouse/normal mouse aggregation chimeras

Aggregation chimeras were formed between C57BL/6 mice heterozygous for the Apc(min) (Min) mutation and wild-type SWR mice, that differ in their Pla2g2a status, a modifier of Apc(min), and also in their resistance to intestinal polyp formation. Variation in the dolichos biflorus agglutinin-staining patterns of the intestines of these mouse strains was used to determine the chimeric composition of the intestine in individual mice and to examine the clonal composition of adenomas. Macroscopic adenoma numbers in chimeric mice were compared with the expected adenoma numbers based on the percentage of C57BL/6J-Apc(min/+) epithelium in individual mice. These results unexpectedly show that there was no apparent inhibitory effect of the SWR-derived (Pla2g2a wild-type) tissue on adenoma formation in the C57BL/6J-Apc(min/+) epithelium. This suggests that the main genetic modifiers of the Min phenotype act at a cellular or crypt-restricted level with no discernable systemic effect. All adenomas were seen to contain C57BL/6J-Apc(min/+)-derived epithelium, confirming that the germ-line mutation of the mApc gene is necessary to initiate tumorigenesis in this model system, and that the mApc gene acts in a cell autonomous fashion.

Clinical models of chemoprevention for colon cancer

Colon cancer is a common malignancy in the westernized world and is incurable in its advanced stages. This article summarizes the currently available information on colorectal cancer chemoprevention. A brief outline of the incidence and etiologic factors is followed by a discussion of the evidence on which chemopreventive strategies for colon cancer are modeled. This includes a description of the development of surrogate endpoint biomarkers and experimental models to study colorectal cancer chemopreventives, a review of the promising colorectal cancer chemopreventives, and a discussion of the issues to be addressed in the design of future chemoprevention trials. The article concludes with an emphasis on the development and validation of biomarkers and selection of high-risk cohorts using genetic and epidemiologic tools as the main goals of future colon cancer chemoprevention trials before large-scale, risk-reduction trials are conducted.

Detection of colorectal neoplasia with peanut-agglutinin (PNA)-reactive carbohydrate structures in rectal mucus

In contrast to normal colorectal mucosa, peanut-agglutinin-(PNA)-reactive glycoconjugates are commonly expressed in most colorectal carcinomas and in some pre-malignant conditions such as adenomas and ulcerative colitis. Since enzymatically detectable galactose-beta1-3-N-acetyl-galactosamine residues are found in rectal mucus obtained from patients with carcinoma of the large bowel, it was investigated here whether PNA-reactive carbohydrate structures in rectal mucus can be exploited in the detection of colorectal neoplasia. Samples of rectal mucus obtained from 261 randomly selected patients with colorectal symptoms were applied on nitrocellulose filters. The presence of PNA-reactive glycoconjugates in mucus samples was determined by a peroxidase-conjugated PNA-overlay procedure. The results were correlated to findings from total colonoscopy/surgery and histopathology. PNA-reactive carbohydrate structures were detected in 76% of patients with carcinoma (p < 0.005), in 62% of patients with adenoma (p < 0.005), in 69% of patients with inflammatory bowel disease (p < 0.005), and in 38% of patients with hyperplastic polyps (NS), in contrast to 21% of the control subjects with macroscopically normal colorectal mucosa. These results show that PNA-reactive carbohydrate alterations in rectal mucus correlates with neoplastic and hyperproliferative conditions of the colorectal mucosa. The specificity of the PNA test for colorectal neoplasia was 76%. Therefore the use of more discriminate carbohydrate probes are needed for the pre-symptomatic detection of colorectal neoplasia.

Relationship among colonocyte proliferation, differentiation, and apoptosis as a function of diet and carcinogen

To determine the relationship among colonocyte proliferation, differentiation, and apoptosis as a function of fiber and carcinogen, we conducted a 2 x 2 factorial design study with two fibers (pectin or cellulose) and two injection protocols (azoxymethane or saline) in male Sprague-Dawley rats. Rats were killed six weeks after the injections, and in vivo cell proliferation was measured by incorporation of bromodeoxyuridine into DNA, differentiation by binding of the lectin Dolichos biflorus agglutinin, and apoptosis by immunoperoxidase detection of digoxigenin-labeled genomic DNA. In the proximal colon, pectin decreased differentiation and apoptosis, resulting in a greater number of cells per crypt column. In the distal colon, pectin increased cell proliferation, resulting in more crypts per millimeter of colon and a greater number of surface cells. Azoxymethane increased cell proliferation and decreased differentiation and apoptosis in the proximal and the distal colon. This resulted in a greater number of surface cells proximally and more crypts per millimeter of colon distally. These results illustrate the importance of considering all three parameters (proliferation, differentiation, and apoptosis) when evaluating neoplastic growth.

Detection of Tn, sialosyl-Tn and T antigens in hereditary nonpolyposis colorectal cancer

The simple mucin-type carbohydrate antigens Tn, sialosyl-Tn, T and the 'cryptic' sialylated variant of the last represent the mucin core oligosaccharide structures that are produced in the initial steps of the mucin biosynthetic pathway. Utilizing monoclonal antibodies anti-Tn antigen (HB-Tn1), anti-sialosyl-Tn antigen (HB-STn1), anti-T antigen (HB-T1) and the biotinylated Amaranthus caudatus agglutinin (ACA), we have investigated the expression of the simple mucin-type carbohydrate antigens in hereditary nonpolyposis colorectal cancer (HNPCC; 15 cases) compared with sporadic colorectal cancer (CRC; 60 cases) and normal colonic mucosa (30 cases). A variable positivity of Tn, sialosyl-Tn, T and the cryptic sialylated form of this latter antigen was encountered in both HNPCC and sporadic CRC cases; in addition, in normal colonic mucosa a constant reactivity was encountered only for Tn and the cryptic sialylated form of T, while negative results were always obtained for sialosyl-Tn and T antigens. Statistical analysis, performed using a Chi-square test, showed significantly lower (P = 0.037) expression of sialosyl-Tn and higher (P = 0.022) expression of T in HNPCC than in sporadic CRC, suggesting a greater presence of beta 1,3 galactosyltransferase activity in HNPCC than in sporadic CRC. We were unable to identify a peculiar phenotype for HNPCC with simultaneous evaluation of reactivity for HB-Tn1, HB-STn1, HB-T1 and ACA; the biological significance of the preferential expression of T antigen in HNPCC remains to be investigated.

Colorectal mucin histochemistry in health and disease: a critical review

Neoplastic, inflammatory and regenerative processes affecting colorectal mucosa are associated with alterations in structure of epithelial mucin. This review collates mucin-, lectin-, and immuno-histochemical observations on colorectal mucins and introduces recent molecular genetic insights into the structure of the protein backbone of mucins. The numerous structural modifications uncovered by the various technical approaches have been reduced to a few manageable principles that are of relevance to both researcher and diagnostic pathologist. Particular attention is drawn to the need to appreciate the limited specificities of probes, the confounding influences of anatomical site and genetic factors (necessitating the use of appropriate positive and negative control tissues) and the precise location of secretory material. In the past, insufficient attention has been given to the effects of altered differentiation including metaplasia and differing lineage expression in epithelial disorders of growth. It is likely that certain changes loosely ascribed to goblet cell mucin, such as neo-expression of blood group antigens and anomalous expression of core carbohydrate structures, do not occur at all. Critical examination of available data point to only two consistent and unequivocal changes affecting goblet cell mucin in pathological processes: loss of O-acetyl substituents at sialic acid C4 and C7,8,9 and increased sialylation. Furthermore, there are no neoplasia-specific alterations in mucins documented to date. All neoplasia-associated changes have been described in non-neoplastic lesions also.

Glycoconjugates of the normal human colorectum: a lectin histochemical study

Previous studies of the normal human colorectum by lectin histochemistry have used a mixture of tissues, including those derived from colons harbouring neoplasia and inflammatory bowel diseases. In the current investigation, tissues from patients without either of these conditions have been examined with a wide panel of lectins, encompassing specificities directed against both N- and O-linked sequences, using an avidin peroxidase revealing system and evaluated with a semiquantitative scoring method. The results of binding of these lectins have been compared with those seen in the resection margins of (at least 5 cm away from) colorectal carcinomas. Consistent regional variations were noted between right- and left-sided colonic tissues, with more diverse glycan structures and a greater sialyl content in the distal colon. There was evidence of graduation of formation of oligosaccharide chains in developing crypts, possibly related to the maturation and expression of glycosyl transferases responsible for the incorporation of mannose residues of N-linked oligosaccharides and of N-acetylgalactosamine and N-acetylglucosamine. Comparison with previous reports has revealed some variations, possibly related to tissue fixation and processing and to lectin concentrations employed, which raises the question of standardization of methodologies in lectin histochemical investigations.

The lectin Griffonia simplicifolia I-A4 (GS I-A4) specifically recognizes terminal alpha-linked N-acetylgalactosaminyl groups and is cytotoxic to the human colon cancer cell lines LS174t and SW1116

The lectin GS I-A4 binds to terminal alpha-N-acetylgalactosaminyl (GalNAc) groups (which include the Tn antigen), but not to the closely related tumor-associated epitope, sialylated Tn antigen. The lectin also precipitates asialo OSM, but not its native sialylated form. Lectin histochemistry with human colonic tissues showed that GS I-A4 specifically stained specimens of colon cancer and colonic tissues from individuals with FAP; however, normal colonic tissues from patients without colonic disease were rarely stained with this lectin. Glycoconjugates bound by GS I-A4 were observed on the surface membranes of 2 human colon cancer cell lines, LS174t and SW1116, when fluorescein isothiocyanate (FITC)-conjugated GS I-A4 was used. GS I-A4 was toxic to these 2 human colon cancer cell lines in monolayer culture. A dose-response study conducted using 10-160 micrograms/ml, of GS I-A4 demonstrated significant dose-related toxicity against LS174t and SW1116 cells. At concentrations > 80 micrograms/ml, > 99% of LS174t and > 90% of SW1116 cells were killed. Four mM GalNAc specifically inhibited the cytotoxic effect of GS I-A4 (p < 0.001), whereas 4mM N-acetylglucosamine (GlcNAc) had no effect. Two other lectins that recognize terminal alpha-GalNAc residues, DBA and LBL, were significantly less cytotoxic to the colon cancer cells than GS I-A4. In the light of these findings, we speculate that GS I-A4 may have potential use as a diagnostic agent against colorectal cancer.

Dolichos biflorus agglutinin binding in hereditary bowel cancer

Dolichos biflorus agglutinin (DBA) binds specifically to N-acetylgalactosamine (GalNAc), one of the 5 sugars contributing to the oligosaccharide component of human colorectal goblet cell mucin. DBA binds to goblet cells of the upper crypt and surface epithelium within the proximal colon and to the majority of goblet cells of the distal large bowel. DBA therefore serves as a marker of colorectal goblet cell differentiation with a distinct proximal to distal gradient effect. Previous reports indicate significant loss of DBA reactivity within morphologically normal colorectal mucosa derived from at-risk members of hereditary non-polyposis colorectal cancer (HNPCC) families. This finding could not be confirmed in the present study. Reduced binding was a relatively consistent finding in transitional mucosa, hyperplastic polyps and carcinoma, with adenomas displaying a more varied pattern of loss. Reduced binding by DBA may be explained by several mechanisms and may not necessarily reflect loss of GalNAc. The concept that lectins can be used to identify stepwise changes that occur during neoplastic evolution should not be accepted uncritically.

Prognostic value of the histochemical expression of helix pomatia agglutinin in advanced colorectal cancer. A univariate and multivariate analysis

PURPOSE

The expression of helix pomatia agglutinin in advanced colorectal cancer was evaluated in order to determine whether helix pomatia agglutinin could serve as an effective prognostic indicator.

METHODS

Using the histochemical procedure, the expression of helix pomatia agglutinin was studied in 117 patients with primary colorectal cancer. Sixty of 117 patients who died of either recurrence or metastasis within two years (Group 1) after resection were compared with the other 57 patients who survived for five years or longer (Group 2).

RESULTS

The helix pomatia agglutinin-positive expression was seen in 34 cases of Group 1 and in only 15 cases of Group 2 (P < 0.01). Lymph node metastasis, lymphatic invasion, venous invasion, mucin production, and helix pomatia agglutinin expression all had a significant correlation with the prognosis in the univariate analysis; however, only lymph node metastasis, venous invasion, and helix pomatia agglutinin expression were prognostic factors with a significant difference in the multivariate analysis.

CONCLUSIONS

Histochemical expression of helix pomatia agglutinin will indeed aid in accurately predicting the prognosis of patients with advanced colorectal cancer.

Evolution of hereditary bowel cancer

Familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC) are both inherited as autosomal dominant conditions in which the mutation gives rise to a tendency to produce precancerous adenomas. However these two forms of hereditary bowel cancer show important differences at the clinical, pathological and molecular genetic levels. It is argued that the first tissue manifestation of FAP is the unicryptal adenoma. The existence of a preceding field change characterised by diffuse hyperproliferation and various altered phenotypes does not stand up to critical scrutiny. The processes of neoplastic evolution in FAP and HNPCC are compared in detail. It is suggested that an understanding of the function of the FAP and HNPCC genes will lead to the development of cancer prevention strategies aimed at blocking the earliest stages of neoplastic development.

Identification of hereditary nonpolyposis colorectal cancer in the general population. The 6-year experience of a population-based registry

BACKGROUND

Hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome) is an autosomal dominant disease characterized by early-onset intestinal neoplasms, localization of tumors in the proximal colon, and frequent association with cancers at other sites, especially the endometrium, skin, and stomach. The identification of HNPCC is often difficult, owing to the lack of biomarkers and the extreme frequency of sporadic colorectal cancer in the Western World.

METHODS

The authors reviewed the clinical data and the family trees of all patients (n = 817) with colorectal malignancies registered in the local health district between 1984-1989 with the following objectives: (1) to identify families with HNPCC and (2) to establish the frequency of the syndrome in northern Italy. Six clinical criteria were defined (vertical transmission, familial aggregation, early age at onset, right colon localization, multiple tumors, and mucinous carcinoma), all indicative of an increased possibility of HNPCC:

RESULTS

The registered families were divided into various subgroups according to the presence (in the nuclear pedigree) of four or more criteria (41 families, 5.0% of total), three criteria (58 families, 7%), two criteria (73, 8.9%), or less than two criteria (203 families, 24.8%). The remaining 380 case families did not show criteria suggesting a genetic component. One hundred thirty-three genealogic trees were extended further to gather information on second-degree and third-degree relatives. The expanded pedigrees were further analyzed to ascertain if they met the recently proposed requisites for HNPCC: Nineteen of 37 (51%) families with four criteria met the minimum requisites and could therefore be considered HNPCC: Similarly, HNPCC was diagnosed in six extended pedigrees of the three-criteria (16.6%) and in three families (8.5%) of the two-criteria subgroups. The difference in the detection of HNPCC among various subgroups was statistically significant (P < 0.001). From the observed findings, the frequency of HNPCC in this population can be estimated to be between 3.4-4.5% of all cases of colorectal cancer.

CONCLUSIONS

HNPCC can be identified in the general population through the data of a colorectal cancer registry if the nuclear pedigrees of all incident cases are traced and a proportion of them selectively expanded. The observed frequency of HNPCC was rather consistent with previous estimates in other populations.

Genetics, natural history, tumor spectrum, and pathology of hereditary nonpolyposis colorectal cancer: an updated review

Hereditary nonpolyposis colorectal cancer (HNPCC) dates to Warthin's description of family G, which he began studying in 1895. Warthin's observations were not fully appreciated until 1966 when two families with an autosomal dominant inheritance pattern of nonpolyposis colorectal cancer (CRC) and endometrial cancer were described. This condition was first termed the "cancer family syndrome" and was later renamed HNPCC. Some have proposed that HNPCC consists of at least two syndromes: Lynch syndrome I, with hereditary predisposition for CRC having early (approximately 44 years) age of onset, a proclivity (70%) for the proximal colon, and an excess of synchronous and metachronous colonic cancers and Lynch syndrome II, featuring a similar colonic phenotype accompanied by a high risk for carcinoma of the endometrium. Transitional cell carcinoma of the ureter and renal pelvis and carcinomas of the stomach, small bowel, ovary, and pancreas also afflict some families. Current estimates indicate that HNPCC may account for as much as 6% of the total CRC burden. There are no known premonitory phenotypic signs or biomarkers of cancer susceptibility in the Lynch syndromes. This report will summarize current knowledge, with emphasis on the manner in which this knowledge can be employed effectively for diagnosis and management of HNPCC.

Ulex europaeus agglutinin-1 binding in hereditary bowel cancer

Ulex europaeus agglutinin-1 (UEA-1) binds specifically to alpha-L-fucose, the terminal sugar of blood group substances H2 and Ley the expression of which is confined mainly to the proximal colon. The aim of the study was to determine whether there is neo-expression of alpha-L-fucose in the normal appearing mucosa of the distal bowel in subjects with or at risk of hereditary bowel cancer. UEA-1 binding was investigated by means of a direct lectin-peroxidase technique in tissues derived from patients with familial adenomatous polyposis (9) and affected (16) or at risk of (14) hereditary non-polyposis colorectal cancer. Control tissues were obtained from normal subjects and patients with sporadic bowel cancer and no family history of the condition. There was increased expression of alpha-L-fucose in some adenomas (mosaic pattern), in most carcinomas (diffuse), in hyperplastic polyps (crypt base), but not in normal appearing mucosa or transitional mucosa (adjacent to carcinoma) in any of the groups of patients examined. In view of the negative findings for normal-appearing mucosa, the suggestion that there is a pre-neoplastic field change in subjects at risk of hereditary bowel cancer may be unfounded.

Colon cancer genetics

The terms "hereditary," "sporadic," and "familial" colorectal cancer (CRC) suggest a knowledge of causation; however, current understanding of CRC does not permit categorization of differing CRC risks in accord with their cause per se. Despite these serious shortcomings, these terms are defined operationally on the basis of a family history of cancer, and when available, additional phenotypic information. The sporadic type occurs in the absence of a family history of CRC in a first-degree relative. The familial type occurs when at least one first-degree relative has CRC. Both these categories require the exclusion of hereditary CRC. In the case of hereditary CRC, this type is defined as a family history of CRC occurring in a pattern that indicates autosomal-dominant inheritance, which also may involve certain phenotypic signs (depending on the specific disorder, i.e., florid adenomatous polyps, benign and malignant extracolonic lesions, cancer of unusually early onset, and multiple primary cancer, particularly synchronous and metachronous CRC). Although this operational classification does not produce etiologically homogeneous groups, it is believed to have pragmatic utility with respect to planning targeted surveillance and management strategies. Because of the distinctive natural history of CRC in hereditary syndromes, it is of paramount clinical importance to identify hereditary CRC when it does occur. Even in patients with no evidence of hereditary CRC syndrome, their family history may be second only to age in determining the best CRC screening program for those who are asymptomatic. In an attempt to provide a perspective on the clinical evaluation of CRC risk, research was reviewed on pathologic features and biomarkers that may be related to CRC causes, especially the genetic basis of CRC susceptibility. The long-term objective of studies on the genetic epidemiology of CRC is primary and secondary prevention through development of targeted management and surveillance recommendations (based on an understanding of CRC causation) that is relevant to hereditary, familial, and sporadic CRC.

Precursors of colorectal carcinoma. Biopsy and biologic markers

The term biologic marker (biomarker) of colorectal cancer refers in this article to an early preclinical phenotypic characteristic that relates to the risk for developing this cancer. Putative biologic markers in the normal colorectal mucosa of patients at risk include abnormal cell proliferation as determined by kinetic studies, ornithine decarboxylase activity, and polyamine synthesis. Alterations of mucin synthesis have been studied using both histochemical stains and lectin-binding techniques. Blood group and related carbohydrate antigens also have been evaluated as potential biomarkers in the normal mucosa. Biopsy small (less than 5 mm) polyps encountered at endoscopy has become a standard practice. Although a small polyp found to be an adenoma has a low likelihood of harboring high-grade dysplasia or invasive carcinoma, it represents an indicator of risk for colorectal neoplasia. Hyperplastic polyps, however, even though they have certain epidemiologic associations with colorectal neoplasia, are controversial as putative biomarkers of clinical relevance. Current research supports a concept of a field defect of the colorectal mucosa at risk for neoplasia, which may be identified by phenotypic abnormalities of the normal mucosa and the development of small adenomas.

Lectin reactivities as intermediate biomarkers in premalignant colorectal epithelium

Normal colonic epithelial cells undergo maturation as they traverse the crypt to the lumenal surface. The binding of lectins to goblet cell mucins and other glycoconjugates changes as the cells migrate and differentiate. Additional stepwise modifications in glycoconjugate expression occur in premalignant and malignant neoplasms that may be detected by lectin binding studies. The lectins Dolichos biflorus agglutinin (DBA) and soybean agglutinin (SBA) have been developed as markers of differentiation in normal-appearing colonic epithelium. Using a quantitative biometric system to score tissues, reduced levels of lectin binding have been found in rectal tissue from patients with familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer. The lectin Amaranthus caudatus agglutinin (ACA) binds to a cytoplasmic glycoconjugate expressed at the base of the colonic crypt and serves as a possible proliferation marker in the distal, but not proximal, colon. ACA binding increases in tandem with increased levels of proliferation (using BrdU incorporation) in neoplastic tissues. Binding by the peanut lectin (PNA) occurs late in the adenoma-to-carcinoma sequence--in larger adenomas and in cancers--and serves as a marker of advancing neoplasia. Lectins identify the stepwise changes that occur during normal differentiation, proliferation and in advancing neoplasia. By selecting the appropriate probe, biomarkers may be developed for early, intermediate, and late events in colorectal cancer.