An assessment of proliferative and enzyme activity in transitional mucosa adjacent to colonic cancer

Nucleolar organizer regions (AgNOR) and subepithelial vascularization as field cancerization markers in oral mucosa biopsies of alcoholic and smoking patients

OBJECTIVE

The aim of this study was to show that variations in nucleolar organizer regions (AgNOR) and the increase in subepithelial vascularization could reveal changes related to markers of field cancerization in alcoholic and smoking patients who have not yet expressed clinical or histological malignant lesions.

STUDY DESIGN

Quantitative variations in epithelial AgNOR and in the vascularization of the underlying connective tissue were assessed by image analysis in histologically normal biopsy specimens from alcohol drinkers and smoking patients (DS). AgNORs were evidenced by silver staining and vessel walls were labeled by immunohistochemical demonstration of the CD34 antigen. Samples of oral mucosa of nonalcoholic, nonsmoking patients (NDS) obtained during surgical procedures served as controls. Eight parameters related to number, volume, and shape of nuclei and AgNORs, and 4 parameters related to number and diameter of vascular sections were evaluated. Differences between DS and NDS groups were statistically evaluated by means of ANOVA test and posterior Bonferroni comparisons.

RESULTS

The morphometric analysis revealed more irregular-shaped AgNORs in the superficial and suprabasal layers of the oral mucosa of DS patients. The suprabasal layers also exhibited a significantly larger number of AgNORs. The normal oral mucosa of DS patients exhibited a greater vascular density, with predominance of small-caliber blood vessels underlying the basement membrane.

CONCLUSION

The variations in AgNOR and epithelial vascularization would be practical biomarkers to evaluate changes underlying the augmented risk of cancerization in oral mucosa.

Prostanoids, ornithine decarboxylase, and polyamines in primary chemoprevention of familial adenomatous polyposis

BACKGROUND & AIMS

Familial adenomatous polyposis because of germline mutation of the adenomatous polyposis coli gene is characterized by development of colorectal adenomas and, ultimately, colorectal cancer. The usefulness of colorectal mucosal compounds to predict the effect on adenoma development of primary chemoprevention with the nonsteroidal anti-inflammatory drug sulindac was evaluated.

METHODS

A randomized, double-blind, placebo-controlled study of 41 subjects genotypically affected with familial adenomatous polyposis but phenotypically unaffected was conducted. Patients received either sulindac or placebo for 48 months, and development of new adenomas was evaluated. The levels of 5 prostanoids, ornithine decarboxylase, and polyamines were measured serially in normal-appearing rectal mucosa.

RESULTS

There were no statistically significant differences between treatment groups in baseline levels of prostanoids, ornithine decarboxylase, or polyamines. At conclusion of the study, 4 of 5 prostaglandin levels were statistically significantly lower in the sulindac group than in the placebo group. Among the subset of patients taking sulindac, 3 of 5 prostaglandin levels were statistically significantly lower in patients who were polyp free than in those who developed polyps. By contrast, there were no statistically significant differences in ornithine decarboxylase or polyamines between treatment groups or in those on sulindac who were polyp free compared with those who developed polyps.

CONCLUSIONS

Colorectal mucosal prostaglandin levels, but not ornithine decarboxylase or polyamines, may be valuable biomarkers to assess appropriate drug dosage and medication compliance in patients undergoing primary chemoprevention therapy with sulindac. Reduction of mucosal prostaglandin levels may be necessary to achieve chemopreventive benefit from this agent.

Review article: chemoprevention of colorectal cancer

Colorectal cancer is a disease with a high mortality at present, due to the late stage at which many cases present. Attention is therefore focusing on preventative strategies for colorectal cancer given that polyps appear to be identifiable and treatable precursor lesions of this disease. Endoscopic polypectomy has been shown to reduce the incidence of colorectal cancer and there is a good case for endoscopic screening of the general population. However, this will require a large amount of manpower and resources and its success will also depend on the overall compliance of the population. Epidemiological studies have shown that individuals reporting a regular intake of aspirin and other non-steroidal anti-inflammatory drugs have a reduced risk of developing colorectal polyps and cancer. Similarly, a number of natural substances, such as calcium and folate, when supplemented regularly in the diet, have also been linked to a possible decreased incidence of colorectal cancer. This has led to the concept of using such agents to reduce the number of cases of colorectal cancer. In this article, we review the current evidence for the use of these and other agents for the chemoprevention of colorectal cancer, together with theories as to their possible mechanisms of action.

Colorectal carcinoma associated with serrated adenoma--prevalence, histological features, and prognosis

Serrated adenoma has been proposed to be a distinct entity among colorectal neoplasms. Progression to frank carcinoma has been suggested in individual cases, but the prevalence of carcinomas originating from serrated adenomas and their clinico-pathological characteristics are not known. In the present study, a large series of colorectal cancers was analysed for the occurrence of serrated adenoma in association with carcinoma and clinico-pathological features were compared in cases with and without serrated adenoma. Specimens from 466 colorectal carcinoma patients undergoing operations between 1986 and 1996 were re-evaluated for the presence of juxtaposed serrated adenoma and carcinoma. Clinico-pathological features such as location, Dukes' stage, histological grade, mucinous differentiation, and prognosis were evaluated. Twenty-seven carcinomas (5.8%) were found in association with an adjacent serrated adenoma. Eight of the patients were male and 19 were female. All of these adenocarcinomas showed a serrated appearance resembling that of serrated adenomas. Nine (33%) cases were mucinous and a mucinous component was present in 11 (41%) additional cases. The majority of the tumours were located either in the caecum (14 cases; 51%) or in the rectum (9 cases; 33%). DNA microsatellite instability was more common in carcinomas associated with serrated adenoma (37.5%) than in other carcinomas (11.0%). It is concluded that carcinoma associated with serrated adenoma is a distinct type of colorectal neoplasm, accounting for 5.8% of all colorectal carcinoma cases in this study. Predilection for the caecum and the rectum may reflect their aetiological factors. Female preponderance is contrary to that reported for hyperplastic polyps and serrated adenomas.

Colossal crypts bordering colon adenomas in Apc(Min) mice express full-length Apc

Enlarged but nondysplastic crypts are frequently observed at the margins of colon tumors, forming what has been called a transitional epithelium. It is now thought that this is a reactive state and not a preneoplastic condition as previously suggested. We have used the mouse familial adenomatous polyposis model, ApcMin, to study these abnormal adenoma-associated crypts. We report that these nondysplastic crypts are enormous (as much as 10 times normal length) and branch more frequently than normal crypts. They express wild-type Apc protein and display the wild-type Apc allele. We conclude that the colossal crypts at adenoma margins have normal Apc gene function, consistent with the suggestion that their phenotype is a reactive state. The cause remains an open question, but the dramatic epithelial response hints at the presence of potent epithelial trophic factors in the vicinity of colon tumors.

Colonic retinoblastoma protein and proliferation in cancer and non-cancer patients

Both suppressor oncogene and proliferative activity are believed to indicate colon cancer risk. The retinoblastoma (Rb) gene is a suppressor oncogene affecting cell differentiation. Retinoblastoma gene inactivation is associated with tumour development. However, the relation of the Rb protein to cell proliferation and colon tumour formation is unknown. Retinoblastoma protein quantity was correlated with proliferative activity in flat, unaffected mucosa specimens from 36 cancer patients, 21 non-cancer control subjects and in 29 tumour tissue samples from cancer patients. Nuclear Rb protein was measured by using automated CAS-200 image analysis of monoclonal antibody labelled frozen sections from fresh, surgically removed tissue. All colon cells within 15 whole crypts were imaged. Proliferative activity was also measured by using analysis with Ki-67 monoclonal antibody. Retinoblastoma protein content correlated directly with proliferative activity in flat mucosa of non-cancer control subjects (r = 0.63; P < 0.001; n = 21). A significant correlation was also found in flat mucosa specimens of non-metastatic (Duke's stages A and B) cancer patients (r = 0.52; P < 0.01; n = 22). However, Rb protein did not correlate with proliferation in flat mucosa from metastatic (Duke's stages C and D) cancer patients (r = 0.03; NS; n = 14) or in cancer tissue (r = 0.068; NS; n = 29). Mucosal Rb protein in the colon normally increases as proliferation increases. Dissociation between Rb protein and colon proliferation may occur in flat mucosa in patients with a higher risk of metastatic tumour growth. Future studies comparing Rb protein quantity and proliferative activity may help identify high-risk colon cancer patients.

p21/WAF1/CIP1 expression in normal mucosa and in adenomas and adenocarcinomas of the colon: its relationship with differentiation

The immunoreactivity of p21 was evaluated in normal mucosa and in adenomas and adenocarcinomas of the human large bowel. In normal mucosa, p21 immunoreactivity was seen in the superficial third of the crypts (maturation compartment) and in surface (terminally differentiated) epithelium, and was mutually exclusive with Ki67/MIB1 reactivity. These data show that p21 expression is inversely related to proliferation and directly related to terminal differentiation. In adenomas, p21-reactive cells were frequently clustered in the superficial areas and were non-reactive for MIB1. In adenocarcinomas, p21 staining was heterogeneous: high p21 expression (19 cases) was associated with lower stage and lack of p53 overexpression. p21-reactive cells were devoid of MIB1 immunoreactivity, but no relationship could be found between p21 and MIB1 labelling indices. p21 heterogeneity may be related to alterations in the p53-dependent induction pathway: high p21 expression was associated with low to absent p53 reactivity, with presumed normal p53 function; low p21 expression was associated with p53 overexpression, with presumed p53 alteration resulting in loss of function.

Cell proliferation kinetics are abnormal in transitional mucosa adjacent to colorectal carcinoma

The transitional mucosa adjacent to colorectal carcinoma shows characteristic morphological and histochemical abnormalities that may be indicative of premalignant changes. Sixteen colorectal carcinomas were studied to analyse the proliferative activity and its distribution pattern in tissue samples from transitional mucosa located within 2 cm of the cancer and from uninvolved mucosa 10 cm from the cancer. Proliferative activity was assessed using a monoclonal antibody to proliferating cell nuclear antigen (PCNA). The total labelling index (percentage of labelled cells in a column) of transitional mucosa was not significantly different from that of uninvolved mucosa and normal control mucosa but it was significantly higher in cancer tissue (P < 0.001). An upward shift of the compartment of proliferating epithelial cells towards the bowel lumen was seen in transitional mucosa. The labelling index of the middle compartment (compartment 3) of the crypt in transitional mucosa was significantly higher than that in uninvolved mucosa and control mucosa (P < 0.001). Unstable cytokinetic change may already have started in apparently normal transitional mucosa. Assessment of cell proliferation kinetics by PCNA immunostaining may be useful in screening for heightened risk of the development of colorectal cancer.

Colorectal cancer and noncancer patients have similar labeling indices by microscopy and computed image analysis

The labeling index (LI), a microscopic measurement of proliferative activity in colonic crypts, is proposed as an indicator of colonic cancer risk. Computed image analysis of proliferative regions is less labor intensive and more objective than is direct microscopy but has not been validated for labeling indices by direct comparison. The authors compared colonic crypt proliferation in 26 cancer and 13 noncancer patients by using Ki-67 monoclonal antibody (McAb) labeling of flat mucosa obtained from surgically removed, frozen specimens. In cancer patients, the mucosa specimen was excised 10 cm away from the tumor, and the LI was determined microscopically for the whole crypt, the upper two thirds, and the upper one third of 15 crypts. Nuclear antigen levels of 15 whole crypts were determined by using the CAS-200 computed image analyzer (Cell Analysis Systems, Elmhurst, IL). Cancer and noncancer specimens were compared as were microscopically determined LI and stained nuclei specimens by using image analysis. No statistically significant difference in proliferative activity of whole crypts, or the upper two thirds of crypts, was observed between cancer specimens and noncancer specimens from using either technique. However, a significant correlation existed between microscopic analysis and computed image analysis of labeled nuclei. Computed image analysis using Ki-67 McAb labeling can be used instead of microscopy to determine crypt LI, but neither method can be used to distinguish cancer specimens from noncancer specimens.

Chromogranin positive cells in colorectal carcinoma and transitional mucosa

AIMS

Immunostaining of chromogranin identifies gastrointestinal mucosal endocrine cells. The detailed distribution and significance of chromogranin positive cells in colorectal carcinomas and in transitional mucosa remain unclear. The aim of this study was to clarify these aspects.

METHODS

The distribution of chromogranin positive cells was studied by immunohistochemical methods in normal epithelium remote from carcinoma, in transitional mucosa, and in carcinomas of the colorectum. In selected cases northern or western blot analyses were performed.

RESULTS

Chromogranin positive cells were seen in the lower third of the normal crypts and less frequently in transitional mucosa. Thirty five per cent (n = 38) of colorectal carcinomas showed immunohistochemically positive carcinoma cells in the tumour tissue. Northern and western blot analyses showed similar results. There was no difference in clinicopathological factors, including prognosis, between chromogranin positive cases of colorectal carcinoma (n = 38) and chromogranin negative cases (n = 70).

CONCLUSIONS

Neuroendocrine cell differentiation is controlled in transitional mucosa and the presence of chromogranin positive cells in carcinoma tissue does not influence the patient's prognosis.

Nucleolar organizer regions in lining epithelium adjacent to squamous cell carcinoma of human oral mucosa

BACKGROUND

The value of silver staining of nucleolar organizer regions (AgNOR) counts as a diagnostic aid has been reported for several neoplastic entities. Previous studies have proved the value of the morphometric evaluation of AgNOR in the detection of incipient cellular alterations.

METHODS

A morphometric analysis of AgNORs was performed in oral mucosa epithelium adjacent to squamous cell carcinoma compared with normal mucosa epithelium and the carcinomatous parenchyma.

RESULTS

Highly statistically significant differences in all 5 AgNOR-related parameters assessed were found between normal mucosa and mucosa adjacent to cancer. Conversely, the corresponding nuclear parameters failed to exhibit significant differences. The parameter AgNOR contour index plotted for individual cases affords a cutoff value that could prove useful in identifying epithelia at early stages of transformation.

CONCLUSIONS

AgNOR evidenced significant variations in epithelium adjacent to oral squamous cell carcinoma, which did not exhibit morphologic signs of atypia. Based on this study, AgNOR would be a quantitative, discriminative aid, easy to monitor in a pathology laboratory, in detecting incipient cellular alterations. These findings contribute to the issue of early diagnosis and to the knowledge of tumoral growth.

Differentiation-associated changes in mucin glycoprotein antigenicity in mucosa adjacent to rare gastrointestinal tract tumours of non-mucosal origin

We have investigated changes in mucin antigenicity and morphology in the perineoplastic mucosa adjacent to rare, predominantly non-mucosal gastrointestinal (GI) tumours. Twenty-nine tumours of small and large intestine, including primary mesenchymal and ectodermal tumours, were examined immunohistochemically using 11 monoclonal antibodies (MAbs) raised against SIMA and LIMA (small and large intestinal mucin antigens). Non-epithelial GI tumours were essentially non-reactive, while adjacent mucosa showed altered mucin expression and morphology, in particular, features of transitional mucosa (TM). Combinations of different SIMA epitopes were detected adjacent to all colorectal tumours, and, similarly, LIMA epitopes adjacent to small intestinal tumours. Specific patterns adjacent to certain tumours may reflect influences of factors produced by individual tumours on mucin composition. Altered antigenicity and morphology in TM thus appear to be reactive changes in response to a wide range of GI tumours, presumably as a consequence of factors secreted by the tumour and/or a host response to the tumour.

Intermediate biomarkers of increased risk for colorectal cancer: comparison of different methods of analysis and modifications by chemopreventive interventions

Intermediate biomarkers of abnormal cell growth and development have recently been used in chemoprevention trials in attempts to identify the efficacy of chemopreventive agents in human subjects. Measurements carried out include those related to cell proliferation, differentiation, and gene structure and expression in the colon. Among modified patterns of cell proliferation identified by microautoradiographic or immunoperoxidase assays, a characteristic expansion in the size of the proliferative compartment has been observed in normal-appearing colorectal mucosa of human subjects with disease increasing cancer risk; the same patterns have been induced by chemical carcinogens in rodents. Moreover, this intermediate biomarker has been modulated by chemopreventive agents in both rodents and humans. Newer intermediate biomarkers being studied for application to human chemopreventive programs include normal and abnormal patterns of expression of mucins, intermediate filaments and cytoskeletal proteins, and the structure and expression of a variety of genes associated with normal and abnormal cell development. The application of these various intermediate biomarkers to chemoprevention studies is increasing the ability of investigators to analyze the effects of novel chemopreventive agents in the colon and in other organs.

The clinical and biological significance of the transitional mucosa adjacent to colorectal cancer

The underlying nature of the transitional mucosa adjacent to colorectal cancer is defined and the evidence for and against the statement that this transitional mucosa involves primary premalignant change presented in this article. An association between mucin histochemical changes at the margins of resection and a poorer clinical outcome of patients has been recognized in patients with colorectal cancer after surgery. The retained transitional mucosa at the margins of resection appears to correlate with tumor recurrence and a poorer survival in patients who have undergone radical resection. It is considered that the transitional mucosa adjacent to colorectal cancer and its presence at the margins of resection may be an important prognostic marker for patients with large bowel cancer following radical resection.