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C R Boland

Publications and source records attributed to C R Boland.

At least 91 records · Page 5Linked to original sources
PubMed1990

The carbohydrate composition of mucin in colonic cancer.

Mucins synthesized in colonic cancer are known to be different from those in the normal colon; however, the biochemical differences between these mucins have not been defined. We have purified mucins from samples of nonneoplastic (normal) human colon and colon cancer and found that the carbohydrate content of the cancer-associated mucins is 48% of that in the normal colon, including significant reductions in galactose, N-acetylglucosamine, N-acetylgalactosamine, and fucose. By subjecting the mucins to alkaline degradation, we determined that there are 19% fewer oligosaccharide chains per milligram of cancer-associated colonic mucin than there are in mucins from normal colons. We also found a reduction in mean oligosaccharide chain length in cancer-associated mucin (5.83 carbohydrate residues per chain) compared with those derived from normal colons (10.2 residues). Total and individual amino acid contents were greater in cancer-associated mucins, with the exception of three amino acids (threonine, serine, and proline), two of which represent the O-linked glycosylation sites for glycoproteins. Thus, mucins are aberrantly glycosylated in colon cancer, both in terms of the number and mean chain length of the oligosaccharide moiety. Because of their relative abundance in colonic tissue, mucins appear to be useful molecular species in the study of the derangements in protein glycosylation that occur during neoplasia.

Amino Acids↗
PubMed1990

Characterization of mucous cell synthetic functions in a new primary canine gastric mucous cell culture system.

Mucin is a critical component of the protective layer secreted by gastrointestinal mucous cells. A detailed understanding of the molecular processing of gastric mucin and the physiology of its secretion has been limited by the lack of an adequate model for their study. We have developed a primary culture system of canine gastric mucous cells that has permitted us to study their synthetic and secretory functions. It was found that [3H]glucosamine used for metabolic labeling studies was incorporated into both mucin and lipid components of gastric mucus. To measure mucin with this model, a new immunoassay was developed to quantitate canine gastric mucin. Mucin was purified from the canine stomach, a polyclonal antibody was generated, and an enzyme-linked immunosorbent assay for gastric mucin was established. Mast cells were frequent contaminants of the gastric mucous cell preparation, and two methods were developed to limit their contamination. A new culture system has been developed for the study of gastric mucous cells. These cells synthesize and secrete both mucin and phospholipids. This system will permit us to study the molecular processing of mucin and the physiology of its production and release.

Animals↗
PubMed1989

Analysis of cancer-associated colonic mucin by ion-exchange chromatography: evidence for a mucin species of lower molecular charge and weight in cancer.

Cancer-associated mucins in the colon are antigenically distinct and glycosylated differently from their normal counterparts. Mucin-rich glycoconjugate preparations were made from nine non-neoplastic colons, seven colon cancers, and two different xenografts from mucin-producing human colon cancer cell lines, and radiolabeled with 3H. The preparation was applied to a DEAE-cellulose ion-exchange column, and eluted with a discontinuous ascending NaCl gradient resulting in seven discrete fractions or 'species'. Over half of the 3H-labeled glycoconjugates from specimens of non-neoplastic colonic epithelium eluted in fraction V (eluted with 0.25 NaCl). Significantly less of the 3H-labeled glycoconjugates from specimens of colon cancer eluted in fraction V (34%, P less than 0.0005), and there were significant increases in glycoconjugates eluted in fractions IV (P less than 0.008), III (P less than 0.0005), and II (P less than 0.028). Additional samples were prepared without the radiolabeling procedures, chromatographed on a DEAE-cellulose ion-exchange column, and analyzed for monosaccharide content. Each of the fractions contained the monosaccharides expected in mucin-type glycoproteins, but only sialic acid was differentially expressed in the seven fractions or 'species', occurring principally in the more charged species. However, differences in sialic acid content were not sufficient to explain the differences in retention on the ion-exchange column, nor were differences in O-acetylation of the mucins. Mucin-type glycoconjugates from colon cancers are relatively less charged than those from the normal colon, and elute at lower ionic strengths. Of interest, cancer-associated mucins appear to be of lower molecular weight than their normal counterparts. Additional studies of oligosaccharide and apomucin structure will be required to explain the molecular basis of these differences in charge.

Adenocarcinoma↗
PubMed1988

Quantitation of lectin binding sites in human colon mucins by use of peanut and wheat germ agglutinins.

We have developed a novel method for quantitation of lectin binding sites in mucins derived from colon tissues. Binding of peanut agglutinin and wheat germ agglutinin was measured in extracts from normal and malignant human colon epithelium. Binding of wheat germ agglutinin was used as an estimate of the total mucin present in the tissue extract. Peanut agglutinin was found to bind to mucin from normal colon, but at levels that may be difficult to appreciate by fluorescence microscopy. The yield of mucin extracted from colon cancer was more variable than that from normal colon, and the binding ratio of peanut agglutinin to wheat germ agglutinin was greater in extracts from tumors than in normal tissues. Our findings confirm the histological observation that peanut agglutinin binds more avidly to mucins from colon cancer than to those from normal colon. The finding of peanut agglutinin binding sites in mucins front normal colon was not expected. The quantitative technique may have detected small numbers of binding sites not readily appreciable by fluorescence microscopy. Alternatively, the chromatographic method for measuring lectin binding may be sufficiently sensitive to detect nonspecific binding of the lectin to terminal galactose residues other than the Thomsen-Friedenreich antigen.

Arachis↗
PubMed1988

Assay of lectin binding sites in colon cancer-associated mucins: comparison of fluorescence microscopy with a quantitative chromatographic technique.

We have developed a technique for quantitation of binding of fluorescent lectins to glycoconjugates in specimens of tumors derived from cultured human colorectal cancer cells. Tumor cells were injected subcutaneously into nude mice, giving rise to xenografts that resemble primary human colorectal cancers. The tumors were extracted with saline and were subjected to dialysis and lyophilization. Standardized amounts of the tumor extract were then incubated with fluorescent lectins and subjected to gel permeation liquid chromatography to separate lectin bound to high molecular weight glycoproteins from free (unbound) lectin, and were quantitated using a spectrofluorometer. This assay permitted quantitative measurement of the lectin bound to high molecular weight glycoconjugates such as mucin. The results of this assay were compared with the standard histochemical assessment of tissue labeling by fluorescent lectins. A close correlation between the two techniques was found, especially when little or no labeling was present. Greater variations were observed at higher levels of labeling. The quantitative assay confirms that lectins bind to high molecular weight mucin-type glycoconjugates on fixed sections of tumors, and supports the use of semi-quantitative histochemical assessments of tissue labeling.

Adenocarcinoma↗
PubMed1988

Lectin histochemistry in colorectal polyps.

Lectin histochemistry has permitted an assessment of the glycoconjugate expression in colorectal polyps (Table 8). The T-antigen, a cancer-associated antigen, is expressed in colorectal adenomatous polyps. The apparent expression of T-antigen is related to the methodology used for its detection. FITC-PNA does not bind to glycoconjugates in the normal colon, however it is a sensitive marker for glycoconjugates secreted by colorectal cancers. The binding of FITC-PNA in adenomatous polyps is related to size and histology. The use of biotinylated PNA (followed by avidin-biotin-peroxidase) or PNA:anti-PNA is a more sensitive technique, and the result is that binding may be seen in the normal colon as well as most neoplastic lesions. The use of polyclonal and monoclonal antibodies to the T-antigen are more specific than the PNA:anti-PNA technique. Binding of PAb and MAb anti-T-antigen to colorectal polyps is related to the size of the polyp for both probes, and binding is also related to the degree of dysplasia for the MAb. The future of this work may be directed at an attempt to determine whether a family of closely related antigens are expressed in colorectal neoplasia with varying degrees of affinity for different probes of the T-antigen.

Colonic Neoplasms↗
PubMed1988

Searching for the face of neoplasia.

Modifications of blood group antigens are known to occur in neoplastic tissues of the gastrointestinal tract. We had used lectins, naturally occurring proteins used as molecular probes of carbohydrate structure, to identify a marker of premalignant epithelium in the colon. We used a similar approach to study metaplastic and neoplastic epithelium in the upper gastrointestinal tract, with an emphasis on Barrett's esophagus. The carbohydrate structures (i.e., the glycoconjugates) present faithfully reflected the morphological features, rather than the anatomical location, of each tissue. Of note, only minor modifications in carbohydrate structure were seen in low-grade dysplasia, whereas more distinct changes were seen in high-grade dysplasia and adenocarcinoma. This approach provides insight into the biochemistry and metabolism occurring with disordered maturation of the epithelial cell. The aim of this type of investigation is to develop sensitive markers of earlier neoplasia in the gastrointestinal tract.

Adenocarcinoma↗
PubMed1987

Mucin histochemistry in colonic polyps and cancer.

Mucins are the predominant glycoproteins found in gastrointestinal epithelia, and their structures differ according to the location in the GI tract and the state of cellular differentiation. Different forms of mucin are secreted in colonic polyps and cancers compared to those found in the normal colon. This paper reviews the methods available to probe mucin structure and the state of knowledge regarding the structures of neoplasia-associated mucins. Many of the assumptions made in the interpretation of classical histochemical stains on tissue sections have recently been questioned, and new insight into mucin structure has been gained from the development of newer methodologies such as lectin histochemistry and immunocytochemistry that use well-defined monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1987

Glycoconjugates in the colons of New World monkeys with spontaneous colitis. Association between inflammation and neoplasia.

A spontaneously occurring experimental model of chronic colitis has been described in three closely related species of New World monkeys. One species, Saguinus oedipus oedipus, has the additional feature of developing adenocarcinoma of the colon in this setting. Pathological and lectin histochemistry studies were undertaken in 50 such colonic specimens to determine if pathological or histochemical features were associated with the concomitant development of cancer. Chronic inflammation was found in all of the colons examined, and 14% had features of acute inflammation, which was significantly associated with those animals that developed cancer. An oncofetal glycoconjugate structure has been defined in human colons by the ability to bind peanut lectin. A similar glycoconjugate, probably a mucin, was expressed in the colons of 65% of these animals. A marked degree of expression of the mucin was significantly associated with those animals that developed cancer. A highly significant association was found between the presence of acute inflammation and the expression of the mucin. These studies demonstrate similarities in glycoconjugate expression between the human colon and the New World monkey model of spontaneous colitis. A form of mucin is expressed in these animals that is highly associated with both the presence of acute inflammation and the development of cancer elsewhere in the colon. In addition, an association between acute inflammatory activity and neoplasia was found, suggesting a potential etiologic linkage between the two.

Animals↗
PubMed1987

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.

Adenocarcinoma↗
PubMed1987

Glycoconjugate expression in normal, metaplastic, and neoplastic human upper gastrointestinal mucosa.

Glycoconjugate structure in upper gastrointestinal epithelium was studied using five lectins to determine the relationship between aberrant differentiation and glycoconjugate expression. Specimens of normal esophagus, stomach, and duodenum were examined and compared with specimens of columnar metaplasia in the esophagus (Barrett's esophagus) and specimens of adenocarcinoma of the esophagus and stomach. Specific terminal glycoconjugate structures were found for the esophagus, stomach, and duodenum. Minor differences were found between the antral and fundic gland mucosae, reflecting their respective cell populations. In biopsies of Barrett's esophagus, gastric-type columnar metaplasia expressed glycoconjugates indistinguishable from those in the normal stomach. In specialized-type columnar metaplasia, a more restricted expression of glycoconjugates was seen resembling the normal duodenum. The presence of low grade dysplasia in Barrett's esophagus associated with adenocarcinoma had no impact on glycoconjugate expression. However, a distinctive difference in glycosylation was seen in high grade dysplasia of the columnar-lined esophagus and in adenocarcinoma of the esophagus and stomach. Barrett's esophagus is a morphological mosaic in which the glycoconjugate expression resembles that seen in the normal stomach and duodenum. However, in high grade dysplasia and carcinoma, variable deletion of glycoconjugate expression can be found.

Adenocarcinoma↗
PubMed1986

Pseudomyxoma peritonei. Radiologic features.

Diagnostic radiologic features of pseudomyxoma peritonei consist of diffusely scattered plaques of calcifications in the abdomen, poorly defined soft tissue masses and ascites on plain abdominal radiographs, characteristic scalloping of the hepatic margin, numerous multilocular cystic masses with rims of curvilinear calcifications and compression of abdominal viscera without evidence of invasion at computed tomography, and an echogenic mantle with ascitic septations at ultrasonography. In an appropriate clinical setting, this spectrum of radiologic features is highly specific for the diagnosis of pseudomyxoma peritonei.

Humans↗
PubMed1986

Comparison of T-antigen expression in normal, premalignant, and malignant human colonic tissue using lectin and antibody immunohistochemistry.

The Thomsen-Friedenreich antigen has been implicated as a cancer-associated antigen in some human organs including the colon. Most previous studies of Thomsen-Friedenreich antigen expression in the colon used peanut agglutinin (PNA) to identify the immunodeterminant in tissues. However, evidence from other organs suggests that anti-T antibodies have specificities which differ from those of peanut lectin. To elucidate the nature of the T-immunodeterminant in colonic mucosa, we compared staining by PNA to that of a polyclonal (PAb) and monoclonal (MAb) anti-T antibody. PNA demonstrated the best sensitivity (91%) in cancer tissues but the lowest specificity (68%) in normal mucosa. Staining with MAb was only 76% sensitive but 100% specific. Sensitivity and specificity of PAb were intermediate between PNA and MAb. MAb stained fewer adenomatous polyps than either PNA or PAb, but staining appeared to correlate with premalignant features of the polyps. PNA-binding sites were more prevalent than either PAb or MAb in hyperplastic polyps. Cell cytoplasm was stained by both antibodies more often than by PNA. The majority of fetal colonic specimens stained with all three reagents suggesting that Thomsen-Friedenreich antigen may be an oncodevelopmental antigen in human colon. Differences in staining patterns in some tissues may be due to different antigenic specificities among PNA, PAb, and MAb.

Adenoma↗
PubMed1986

Cancer-associated colonic mucin in cultured human tumor cells and athymic (nude) mouse xenografts.

Mucins derived from colonic cancers differ immunologically and chemically from those in normal colonic epithelium. It has been demonstrated that the lectin from the peanut will bind to mucins present in colonic cancers and other neoplastic lesions but not to those from the normal colon. It was hypothesized, therefore, that in transformed colonic epithelium the glycosylation of mucins occurs differently than in normal epithelium. To rule out the possibility that the differences in oligosaccharide structure were due to postsecretory degradation, studies were designed to evaluate cancer-associated colonic mucins produced under more controlled conditions. We studied nine different cancer cell lines first in monolayer culture and then as xenografts in athymic or nude mice. Eight of the nine cell lines in monolayer culture synthesized glycoconjugates that were labeled by fluorescein-conjugated lectins. After injection into nude mice, eight of the nine cell lines produced tumors typical of human colonic cancer, and six of nine secreted mucin. The mucins produced by the xenografts were labeled at fluorescence microscopy by peanut lectin and other lectins, characteristic of what had been seen in other primary human colonic cancers. One cell line, LS174T, produced large amounts of mucin in the xenograft model. Mucin was purified from these tumors and characterized biochemically. It was demonstrated that mucin purified from the xenografts bound peanut lectin. Therefore, we have concluded that cancer-associated mucins are present in cultured colorectal tumor cells. The cancer-associated mucins are also found in nude mouse xenografts, indicating that they are not the result of postsecretory degradation by colonic flora or by tumor cell necrosis. The cell culture and xenograft can therefore be useful for studying the biosynthesis of cancer-associated mucins.

Animals↗
PubMed1985

Binding of lectins to goblet cell mucin in malignant and premalignant colonic epithelium in the CF-1 mouse.

The lectin peanut agglutinin binds to mucin secreted by neoplastic but not normal human colonic epithelial cells. Peanut agglutinin was found to bind to mucin secreted by experimentally induced neoplasms in the distal colons of CF-1 mice, but not in the distal colons of control animals. Serial examination of colonic tissues after exposure to carcinogen has revealed the "cancer-associated" mucin in histologically normal but potentially premalignant epithelium. Thus, in the chemical carcinogen-rodent model, a diffuse alteration in glycoprotein structure is found in that part of the murine colon that subsequently develops cancer, and this precedes the appearance of neoplastic tissue. Changes in mucin structure may prove to be useful in the identification of premalignant gastrointestinal epithelium in certain humans at high risk for colon cancer.

Animals↗
PubMed1985

Regional differences in normal and cancer-associated glycoconjugates of the human colon.

Because inherent regional differences in colonic epithelium may determine the biologic behavior of tumors originating from different sites, and inasmuch as colonic epithelial cells secrete mucins that may reflect the state of cell differentiation, colonic goblet cell mucin was analyzed with the use of fluorescein isothiocyanate-conjugated lectins and fluorescence microscopy in normal fetal and adult mucosa and in cancers of the proximal and distal colon. In the adult proximal colon only the goblet cell mucin in the upper portion of the crypts was specifically labeled by the lectin Dolichos biflorus agglutinin (DBA), whereas this gradient was progressively lost distally; mucin in the upper and lower crypts of the sigmoid colon and rectum bound the label uniformly. In fetuses less than 22 weeks of age, DBA bound only to mucin in the crypts of the distal colon. Seven of 12 (58%) cancers originating from the proximal colon bound DBA, whereas only 2 of 23 (9%) from the distal colon bound this lectin (P less than .005). Logistic regression analysis suggested that this difference may reflect the occurrence of larger tumors in the proximal colon. Regional differences in the binding of Ulex europaeus agglutinin (UEA-I) to nonneoplastic mucosa was similar to that found by others; predominant binding occurred in the proximal colon in the adult. No difference was noted for UEA-I binding to tumors of the proximal (8 of 12; 66.6%) versus distal (11 of 23; 48%) colon (P = .48). These findings may reflect regional differences in normal and tumor-related carbohydrate structures in mucin of the human colon.

Adult↗