Mucus-associated gastrointestinal antigens in transitional mucosa adjacent to human colonic adenocarcinomas: their 'fetal-type' association

Progression of tumors arising from large ACF is associated with the MUC5AC expression during rat colon MNNG carcinogenis

Aberrant crypt foci (ACF) are microscopic lesions which have been postulated to precede the development of adenomas, precursors of colon cancer. The gastric M1/MUC5AC mucin has also been described as an early marker of colon carcinogenesis in the human and in the rat. To study changes in mucin expression associated with the genesis of tumors, Wistar rats were treated by intrarectal instillations of MNNG, twice a week for 2 weeks, and were sacrificed 10 (n = 20), 14 (n = 20), 22 (n = 20), 30 (n = 10) and 66 (n = 16) weeks after the beginning of the treatment. In the treated rats, the MUC5AC mucin was mainly expressed in ACF compared with the histologically normal mucosae, which showed few isolated MUC5AC-positive normal crypts. During carcinogenesis, the percentage of large ACF [> or =10 aberrant crypts] increased and the number of MUC5AC-positive (NCs) decreased. At Week 30, small tumors were observed arising from large ACF, both types of lesions expressing MUC5AC. At Week 66, large tumors showed remnants of MUC5AC-positive ACF in their adjacent mucosae. This observation suggests that the expression of MUC5AC is associated with the ACF/adenoma sequence and supports the notion of large ACF as precursors of adenomas/adenocarcinomas. Moreover, the expression of MUC5AC in the transitional mucosa adjacent to both rat and human colon tumors suggests that some human tumors could arise from large ACF, and reinforces the concept of the premalignant potential of these lesions.

Biopathologic characteristics of DNA content in crypt cells of transitional mucosa adjacent to carcinomas of the rectum and rectosigmoid

The transitional mucosa (TM) adjacent to carcinomas of the large bowel shows histologic and mucin histochemical changes that may indicate premalignant change and may be of prognostic value after radical resection. In this study, 10 anterior resection specimens from patients with carcinomas of the rectum and rectosigmoid were used to compare the nuclear DNA content in TM with those in cancer tissue and with those in nontransitional mucosa (N-TM; i.e., uninvolved mucosa remote from tumors showing normal histologic and mucin histochemical features). The nuclear DNA content was assessed using DNA image cytometry on Feulgen-stained sections. As compared with N-TM, crypts in TM contained greater numbers of cells, were elongated, and were more likely to be branched with marked sialomucin secretion, accompanied by a marked reduction in the normal sulfomucin content. The mean nuclear DNA content in the upper, middle, and lower thirds of crypts was significantly higher in TM than in N-TM, and the nuclear DNA content in TM exhibited no correlation to that in tumors. The results suggest that TM adjacent to carcinomas of the rectum and rectosigmoid has higher proliferative activity, providing further evidence that TM may be an unstable premalignant change.

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.

Transitional mucosa in human colorectal lesions

Mucosa adjacent to colorectal disease was studied mucin-histochemically. Selected specimens were also studied immunohistochemically for carcinoembryonic antigen (CEA). Transitional mucosa, which showed elongation of crypts and marked sialomucin secretion, accompanied by a marked reduction in the normal sulfomucin content, was evident in 96 of 100 carcinomas (96 percent), 18 of 36 adenomas (50 percent), and 10 of 30 metaplastic polyps (33 percent). When considering the appearance of transitional mucosa, not only in the neoplastic lesions such as carcinoma or adenoma but also in the begin polyp, the transitional change adjacent to the carcinoma cannot be classified as a precancerous phenomenon; rather, it is a secondary one. The mucin-histochemical study disclosed transitional mucosa in all the 21 carcinomas less than 1 cm in diameter and immunohistochemical staining for CEA showed no remarkable change in the adjacent mucosa. Thus, it seems apparent that a change in mucous secretion precedes that of CEA expression in the mucosa adjacent to the carcinoma.

Sialomucin at the resection margins and likelihood of local recurrence of carcinoma of the rectum after anterior resection

The histochemical changes in mucin at the postoperative resection margins in carcinoma of the upper and middle third of the rectum after anterior resection were studied retrospectively in 52 patients. The sialomucinous change was most likely to occur at the intestinal margins of those patients who had tumour recurrence (P less than 0.001). The histological types of tumour, degree of differentiation, Dukes' stages and their distance from the anal verge were virtually the same in patients with and without tumour recurrence. By using high iron diamine-alcian blue staining technique we identified patients with higher risk conditions of tumour recurrence after anterior resection. This technique should increase the likelihood of a cure for patients with recurrent carcinoma of the rectum after anterior resection.

Colonic epithelium reactive monoclonal antibodies. Identification and immunohistochemical localization of the target epitopes

We have produced a small library of colonic mucosa and colorectal carcinoma reactive monoclonal antibodies (MoAbs) by immunizations with extracts of human colon cancer tissue and a human colon cancer cell line. Hybridoma supernatants were tested on (normal and neoplastic) human tissues by immunoperoxidase methods to evaluate organ or tissue specificity. Initial biochemical characterization of the target antigens was performed by gelpermeation chromatography, Western blotting and competition assays. Based upon the immunoreactivity patterns and the characteristics of the antigen four groups of MoAbs could be distinguished. The first group concerns the antibodies PARLAM 3, 9 and 10. These antibodies react with an 87 kDa protein moiety in high molecular weight (2-5 x 10(6) Da) glycoproteins. In intestinal and colon mucosa these antibodies showed diffuse binding with goblet cells. In colon carcinoma decreased reactivity with these MoAbs was found. The second group consists of antibodies PARLAM 8, 12 and 13. These antibodies react with large (greater than 5 x 10(6) Da) glycoproteins, most likely with carbohydrate epitopes. By immunohistochemistry in normal colon mucosa the antibodies all show granular supranuclear reactivity with goblet cells. These antibodies show increased reactivity with colon adenomas and adenocarcinomas. A third group is formed by PARLAM 2, which also reacts with a large (greater than 5 x 10(6) Da) glycoprotein, showing a granular distribution in goblet cells. In colon carcinomas more extensive expression is found than in normal colonic mucosa. Finally, the fourth group consists of PARLAM 11, which also reacts with a large (greater than 5 x 10(6) Da) glycoprotein, located in the brush border of colonic columnar cells. These antibodies might be useful tools for the analysis of the expression of mucin related glycoproteins in normal, preneoplastic and neoplastic colon mucosa.

Intestinal mucin antigens in ulcerative colitis and their relationship with malignancy

The expression of two intestinal mucin-associated antigens large intestine mucin antigen (LIMA) and small intestine mucin antigen (SIMA) were investigated by indirect immunoperoxidase staining of rectal mucosa from patients suffering from ulcerative colitis with (n = 6) and without (n = 31) associated carcinoma and in noncolitic controls (n = 40). The aim was to assess the relationship between antigen patterns and malignant change. SIMA, which is localised predominantly in the small intestine, is virtually undetectable in the normal adult colonic mucosa. However, this antigen is present in the foetal colon and colonic carcinoma. LIMA is expressed in normal colonic mucosa, but absent from the small intestine. LIMA staining patterns were not significantly different among the three groups. In contrast, expression of SIMA was significantly higher in the patients who had developed carcinoma (6/6) than in the noncancer group (7/71) (P less than 0.001). The presence of SIMA was also significantly related to areas of dysplasia compared to normal (P = .03) or inflammation (P less than .05), but it did not differ from mucosa showing "indefinite" atypia. The finding of 31% SIMA-positive biopsies associated with severe inflammation in colitis with active disease, but no evidence of malignancy, is difficult to explain at the present stage. A followup study would be necessary to determine its significance. Perhaps the most important finding is the increased frequency of SIMA-positive foci in histologically normal mucosa in carcinoma patients compared with the noncancer group (P less than .001), suggesting a field change. These observations may be prove useful for the identification of patients who may be at risk of developing carcinoma.

Ectopic expression of the Y (Ley) antigen defined by monoclonal antibody 12-4LE in distal colonic adenocarcinomas

Monoclonal antibody (MAb) 12-4LE reacts specifically with the alpha Fuc(1-2) beta Gal(1-4) [alpha Fuc(1-3)]GlcNAc-R synthetic oligosaccharide and consequently characterizes the Y (Ley) antigen. In normal individuals, this MAb reacts more strongly on samples from blood group O persons, indicating that the Y structure is better recognized when terminal A or B sugars are not added to the Y structure. In fetal and normal adult gastrointestinal tract, this antibody reacts with the epithelium of stomach, small intestine and proximal colon, but not of distal colon. In the adult, cells from the surface epithelium of the gastric, small intestinal and cecal mucosae express the Y antigen according to the secretor phenotype of each individual, thus characterizing the so-called "upward differentiation" pattern. In contrast, mucus cells of the pylorus and duodenal Brünner glands, as well as Paneth cells, always express the Y antigen irrespective of secretor phenotype, thereby characterizing the so-called "downward differentiation" pattern. Proximal fetal colonic mucosa has the same genetic control as the downward differentiation pattern of the adult. Distal fetal colonic mucosa is negative with anti-Y, as in the adult. Y antigen was not expressed in hyperplastic (10 cases), juvenile (5 cases) or adenomatous (43 cases) polyps, except for some spreading villous adenomas in which rare Y-positive foci could be observed but which were not specifically associated with dysplastic glands. Polyps from familiar polyposis did not express this antigen. In adenocarcinomas, the Y antigen was expressed in 41/45 (91%) of distal tumors and 15/35 (43%) of cecal tumors, independently of ABO phenotype. The ectopic expression of this Y antigen on distal colon adenocarcinomas may be a useful tool in the detection of distal colonic carcinomas.

Transitional mucosa of the colon and tumor growth factors

Transitional mucosa of the colon is the tissue immediately adjacent to a cancer, which has histochemical and ultrastructural features similar to those seen in neoplasia. Therefore, it has been hypothesized in the past that this tissue represents the premalignant antecedent to colonic adenocarcinoma. Other investigators have disputed this explanation because similar changes are found adjacent to colonic lesions other than adenocarcinoma. The hypothesis offered here suggests that transitional mucosa may result from the paracrine influence of tumor growth factors released by the tumor. Candidate peptide hormones known to be produced by tumors are proposed, and a framework is outlined to explain the occurrence of transitional mucosa adjacent to non-neoplastic lesions. Transitional mucosa may be both a genuine reflection of the transformed phenotype and yet a "reactive" phenomenon secondary to the presence of the adjacent tumor.

Differentiation antigens in fetal human pancreas. Reexpression in cancer

An antiserum was raised against pancreatic extracts obtained from human fetuses under 5 months of gestational age. After absorption with adult tissues, this antiserum specifically recognized antigens located in the cytoplasm of fetal pancreatic acini. All of the examined pancreatic tissues, ranging from 3 to 5 months of gestational age, showed a strong positive reaction of most of the acinar cells. The number of stained acini and the staining intensity gradually decreased from 5 months onwards and by the 7th-8th month only a few cells remained positive. Adult pancreas was completely negative as were a variety of normal adult and fetal tissues. This antiserum also reacted with tumor structures in 18/18 pancreatic adenocarcinomas as well as with pancreatic acini in the vicinity of tumor. Primary carcinomas of the liver, large bowel, stomach, breast, urinary bladder, lung and other localizations did not react with this antiserum. In some cases of chronic pancreatitis (3/12) a reaction was observed in a few acinar cells. Immunoblot assay after polyacrylamide electrophoresis revealed, in both fetuses and tumors, two main antigens of approximately 60 kDa and 110 kDa relative molecular weight. Several minor components were also observed. These results suggest that our polyclonal antiserum defines a new group of oncodevelopmental antigens with high organ specificity.

Differentiation features of human pancreatic tumor cells maintained in nude mice and in culture: immunocytochemical and ultrastructural studies

A poorly differentiated human pancreatic adenocarcinoma was maintained in nude mice for more than 3 years. When tumor fragments from xenografts were cultivated in suspension, some became adherent, allowing cell culture. Cytochemical, immunocytological and ultrastructural methods were used to study cell differentiation in both solid tumors and cultures. Pancreatic differentiation features such as cell polarization, production of secretory granules, and M1 and M3 mucus-associated antigens were maintained in the tumor cells, in vivo and in vitro. Moreover, in long-term cell cultures, cells were able to organize themselves spontaneously into duct-like structures. Other differentiation features such as production of pancreatic enzymes and hormones were not expressed. However, differentiation patterns such as an intestinal-like brush border and the presence of the M3 antigen associated with intestinal mucus were observed in both xenografts and cultures. This study shows the possible differentiation patterns which can be expressed by the hypothetical tumor pancreatic stem cell in nude mice as well as in culture.

Differences in the expression of mucus-associated antigens between proximal and distal human colon adenocarcinomas

An immunohistological study showed differences in the expression of mucus-associated gastric M1 and intestinal M3 antigens between the proximal (100 cases) and distal (200 cases) colonic adenocarcinomas. Such a regional difference was not observed in the normal colon. A total of 55% and 78% of proximal tumours produced M1 and M3 antigens, respectively (versus 13% and 47% in the distal tumours). The high percentage of M1 positive proximal cancers could be explained by the higher percentage (i) of mucus-producing tumours, such as signet ring cell (6% vs 1%) or mucinous adenocarcinomas (29% vs 11%); and (ii) of M1(+) well-differentiated adenocarcinomas (45% vs 8.5%) and the presence of undifferentiated carcinoma producing M1 antigens (12% vs 0%). These latter carcinomas were found in older patients (mean age 78 years vs 66 years). These results suggest that, on the proximal side, the stem cells were more often engaged in a differentiation process involving the expression of M antigens than were those of the distal side. Moreover, the proximal stem cells more frequently produce a foetal differentiation program showing simultaneous expression of M3 and M1 antigens (in 48% of proximal tumours, vs 11.5% for the distal side). Around 12% of proximal adenocarcinomas (vs 2% of distal tumours) contained stem cells engaged in a cell differentiation program not observed in the normal adult or foetal colon, involving the predominant expression of M1 antigens associated with an undifferential histological pattern.

Early precancerous modifications in the mucus of human and rat distal colon: a comparative immunohistologic study

The M1 antigens, associated with gastric fucomucin, the early oncofetal precancerous marker for the distal colon, were studied using the immunoperoxidase method in the distal colon. We compared human tumoral mucosa with that of rats during DMH-induced carcinogenesis. In both cases we examined histologically normal mucosa, mucinous hyperplasia, glands with serrated epithelium and hypermature goblet cells like those observed in human hyperplastic polyps, dysplasia, and transitional mucosa. We were able to assess similarities between these rat and human mucosae in terms of the tissue and cell location of these M1 antigens as well as the frequency of occurrence in the different comparative lesions. Thus, we demonstrated that such similarities can be observed not only at a histologic level, but also on a molecular level. The presence of M1 antigens in the human distal colon is comparable to mucous modifications induced by a chemical carcinogen, as observed during DMH-induced carcinogenesis in the rat.

A scanning electron microscopy study of changes in the colonic mucus layer during chemical carcinogenesis

Scanning electron microscopy was used to examine the appearances of the colonic mucus layer of rats during chemical carcinogenesis with dimethylhydrazine. The normal colonic mucus layer had a dense homogeneous appearance and provided a complete cover for the mucosal epithelium. At high magnifications tiny fenestrations could be seen in this mucus layer. During carcinogenesis these fenestrations enlarged, increased in number, and coalesced, causing focal defects in the mucus layer, which eventually broke into strands and clumps of mucus. The findings indicate that the colonic mucus layer develops progressive abnormalities during carcinogenesis which result in breakdown of its integrity and exposure of the mucosal epithelium to colonic contents.

Gastric carcinoma with argyrophilic cells: light microscopic, electron microscopic, and immunochemical study

An immunochemical study of a gastric adenocarcinoma with argyrophilic cells showed two areas of tumor that react differently with the usual histochemical reagents as well as with immune sera against gastrin and mucoprotein associated with antigens. Ninety per cent of the tumor cells were PAS positive and contained M2 antigen, and some also contained M1 antigen. About 30 per cent of the M2-positive cells stained strongly with an antigastrin serum as well as with the argyrophilic reagents. The remaining 10 per cent of tumor cells were signet-ring cells located in several clumps in the tumor. These cells were positive for both PAS and alcian blue and contained intestinal M3 antigen. Forty-five per cent of them also contained M1 gastric antigens. Carcinoembryonic antigen (CEA) was found in the cytoplasm of each tumor cell. The presence of CEA and M1 antigen together indicates a fetal pattern, suggesting that the cells originate from very immature gastrointestinal stem cells.

Clinical aspects of gastrointestinal mucus

In such a bird's eye view of a very complicated and complex literature it is inevitable that significant contributions, particularly from earlier investigators, will have been overlooked. We have tried, however, to provide a reasonable framework for the many presentations and discussions which will take place at this conference. As in the past, it is evident that much needs to be done to reconcile the excellent histochemical studies of gastrointestinal mucus in many diseases with the increasing knowledge of mucin structure and composition. This will only be achieved by extraction of highly pure mucin from diseased bowel. In this regard, post mortem material provides an opportunity for mucin researchers which is not available to workers in other fields because of relative freedom from decomposition. The wedding of mucin technology with immunology is also a major priority. Immunoassay techniques provide the answer to quick and accurate product identification in secretion studies. Specific monoclonal antibodies will provide the route to structural differentiation of antigens in complex mixtures. It is also evident that we must seek to develop a variety of controllable models for the study of functional parameters of mucus in physiological conditions, parasite rejection, neoplasia and inflammatory states. Promising initiatives have been touched upon in this review, but these must only be the beginning. One must conclude, however, by recognizing that advances in knowledge have been truly remarkable since the last conference in 1976. One senses that some of the keys which will one day unlock the gates of this "ill-defined" kingdom are already in hand, while the remainder are at least within reach.

Intestinal M3 antigen, a marker for the intestinal-type differentiation of gastric carcinomas

The mucus-associated intestinal M3 antigen, normally restricted to intestinal goblet cells, was found in 35 out of 100 gastric adenocarcinomas belonging to intestinal (19/64) as well as diffuse (16/36) types according to Laurén's classification. often accompanying the other mucus-associated gastric M1 and M2 antigens. This M3 antigen was predominant over the gastric M antigens in 25 of these 35 tumors; 18 of these belonged to the histological intestinal type. According to the WHO classification, the M3 antigen was found to predominate in all mucinous adenocarcinomas (7/7), was never present in the undifferentiated carcinomas (0/8), but was also found in some tubulo-papillar (16/57) and signet-ring cell (12/27) adenocarcinomas. This antigen could be used as a new criterion and incorporated into a point system containing morphological and tumor cell behavioral considerations; then it would appear to be a good marker for intestinal-type differentiation. Indeed, 22 of these 25 gastric adenocarcinomas which produced predominantly M3 antigen showed such an intestinal-like differentiation. The M antigen pattern of gastric carcinoma suggested a duodenal rather than colonic-type differentiation.