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At least 19 recordsLinked to original sources
PubMed1990

Association between extent of colonic mucosal sialomucin change and subsequent local recurrence after curative excision of primary colorectal cancer.

Two interrelated studies were carried out to determine whether extent of sialomucin change adjacent to a primary colorectal carcinoma predicted local tumour invasiveness and risk of local recurrence. In the first, depth of tumour penetration was correlated with the length of the sialomucin band adjacent to 72 primary colorectal cancers. There was a significant (P less than 0.05) increase in sialomucin band length adjacent to tumours invading adjacent structures compared with those which had not (Mann-Whitney U test), although there was no overall correlation between depth of penetration, Duke's classification or degree of differentiation (Kruskal-Wallis test). A sialomucin band of greater than 3 cm was associated with a 70 per cent probability of adjacent structure (T4) invasion. These observations were then tested prospectively in a second study involving 256 patients to determine whether the presence of a greater than 3 cm sialomucin band could predict local recurrence. Presence of a greater than 3 cm sialomucin band was a significant (x2 = 7.12, d.f. = 1, P less than 0.001) and independent predictor of local but not distant recurrence. In addition both the interval to local recurrence and survival were significantly shorter if a greater than 3 cm sialomucin band was present. However the accuracy of greater than 3 cm sialomucin band as a predictive test for local recurrence was only 70 per cent. The extent of sialomucin adjacent to a primary colorectal cancer does provide a crude assessment of tumour invasiveness and risk of local recurrence.

Aged↗
PubMedDate not supplied

Influence of sialomucins at the resection margin on survival of patients with colorectal cancer.

In a multicentre prospective trial, 281 patients undergoing "curative" resection for colorectal cancer were followed for a mean of 13.6 months (SD 7.2 months). The presence or absence of sialomucin at the resection margin was studied histochemically using the high iron diamine-alcian blue (HID-AB) stain. There were 49 deaths relating to tumour recurrence: 21 in the sialomucin positive group (n = 77) and 28 in the sialomucin negative group (n = 204) (p less than 0.02). Life table survival was correlated against the presence or absence of sialomucin in the resection margin. At the mean follow-up (13.6 months) 85.6% of patients were alive in the sialomucin negative group, and 76.4% of patients were alive in the sialomucin positive group. Regression analysis predicts 32.8% and 18.9% five year survivals for sialomucin negative and positive groups respectively. There was no significant statistical correlation between the presence of sialomucin in the resection margin and the Dukes staging, site or tumour differentiation. The appearance of sialomucin in either resection margin appears to be an early marker of poor prognosis for patients with colorectal cancer.

Adult↗
PubMed2000

Detection of sialomucin complex (MUC4) in human ocular surface epithelium and tear fluid.

PURPOSE: To evaluate human ocular surface epithelium and tear fluid for the presence of sialomucin complex (MUC4), a high-molecular-weight heterodimeric glycoprotein composed of mucin (ASGP-1) and transmembrane (ASGP-2) subunits. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis assays were used to identify sialomucin complex RNA in ocular surface epithelia. Immunoprecipitation and immunoblot analysis were used to identify immunoreactive species in human tears and in the corneal and conjunctival epithelia using antibodies specific for carbohydrate and peptide epitopes on the sialomucin complex subunits. Immunofluorescence staining was used to detect sialomucin complex in frozen sections and impression cytology specimens of human cornea and conjunctival epithelia. RESULTS: ASGP-1- and ASGP-2-specific sequences were amplified from RNA extracted from both conjunctival and corneal epithelial biopsies by RT-PCR. Sialomucin complex transcripts were also detected in these tissues by Northern blot analysis, with a greater level of RNA detected in the peripheral than the central corneal epithelium. Sialomucin complex was immunoprecipitated from tear fluid samples and both corneal and conjunctival epithelia and detected by immunoblot analysis with specific anti-ASGP-1 and anti-ASGP-2 antibodies. The ASGP-1 peptide antibody HA-1 stained the full thickness of the corneal and conjunctival epithelia. In contrast, antibody 15H10, which reacts against a carbohydrate epitope on ASGP-1, stained only the superficial epithelial layers of these tissues. No staining was observed in the conjunctival goblet cells. CONCLUSIONS: Sialomucin complex was originally identified in rat mammary adenocarcinoma cells and has recently been shown to be produced by the ocular surface epithelia of rats. Furthermore, it has been identified as the rat homologue of human MUC4 mucin. The present studies show that it is expressed in the stratified epithelium covering the surface of the human eye and is present in human tear fluid. Expression of a carbohydrate-dependent epitope on the mucin subunit (ASGP-1) of sialomucin complex occurs in a differentiation-dependent fashion. Sialomucin complex joins MUC1 as another membrane mucin produced by the human ocular surface epithelia but is also found in the tear fluid, presumably in a soluble form, as found on the rat ocular surface.

Antibody Specificity↗
PubMed1997

Sialomucin expression is associated with erbB-2 oncoprotein overexpression, early recurrence, and cancer death in non-small-cell lung cancer.

Mucin production, when heavily sialylated, can promote cancer cell invasion and metastasis, and modulate the immune recognition system of the host. To explore the prognostic implication of sialomucin expression in lung cancer, we studied 116 patients with non-small-cell lung cancer (NSCLC). Tumor specimens were stained immunohistochemically with monoclonal antibodies (mAbs) against mucin glycoprotein (17Q2, HMFG2, SM3), and histochemically with periodic acid-Schiff/alcian blue to differentiate neutral mucin from acid mucin, and with high-iron diamine/alcian blue to differentiate sialomucin from sulfomucin. The expression status of two established molecular prognostic factors, the p53 and erbB-2 oncoproteins, were evaluated immunohistochemically. The staining was performed on two separately archived, paraffin-embedded tumor blocks for each patient, with normal lung as a control. Correlations were subsequently made among stains and various clinicopathologic factors. All analyses were blinded, and included Kaplan-Meier survival estimates with Cox proportional hazards regression modeling. Associations were established among adenocarcinoma histotype and erbB-2 overexpression, sialomucin expression, and 17Q2 and HMFG2 immunohistochemical positivity (p < 0.05). Sialomucin expression was closely linked to erbB-2 overexpression (p = 0.01). Significant univariate predictors (p < 0.05) of recurrence and cancer death were surgical stage, p53 expression, erbB-2 overexpression, and sialomucin expression. These four factors remained as independent predictors of early recurrence (p < 0.05) after multivariate analysis. For cancer death prediction, p53 and sialomucin expression had a marginal effect. We concluded that sialomucin expression is also a poor indicator of prognosis, which is associated with erbB-2 oncoprotein overexpression, early postoperative recurrence, and cancer death in NSCLC.

Actuarial Analysis↗
PubMed1998

Sialomucins are characteristically O-acylated in poorly differentiated and colloid prostatic adenocarcinomas.

Mucinous glycoproteins are secreted by prostatic adenocarcinomas and might play important roles in tumor invasion and metastasis. Their histochemical properties on routine biopsy specimens have not been fully characterized. We present a histochemical study of mucin in 21 prostatic adenocarcinomas, with particular focus on the demonstration of different types of sialomucins. We applied the following histochemical techniques to routinely processed, formalin-fixed, paraffin-embedded tissue sections: Alcian blue (pH 2.5) and periodic acid-Schiff to reveal both acidic and neutral mucins; high iron diamine and Alcian blue (pH 2.5) to show sulfated and acidic nonsulfated mucosubstances simultaneously; periodic acid borohydride, potassium hydroxide, and periodic acid-Schiff to demonstrate O-acylated sialic acids; periodic acid thionine-Schiff, potassium hydroxide, and periodic acid-Schiff to differentiate pre-existing glycols from those revealed after saponification procedures; and periodic acid borohydride and periodic acid-Schiff to show C9-O-acylated sialic acid. These techniques are useful tools for demonstrating neutral and acidic (sialo- and sulfo-) mucins and di(C8,C9- or C7,C9-)-O-acylated, tri(C7,C8,C9-)-O-acylated and mono(C9)-O-acylated sialomucins. Most prostatic adenocarcinomas showed acidic mucins, with sialomucins predominating over sulfomucins. Well-differentiated and moderately differentiated noncolloid tumors had non-O-acylated sialomucins. Poorly differentiated tumors contained mono-O-acylated (C9) sialomucins, and colloid-type tumors secreted mono-, di-, and tri-O-acylated sialoglycoproteins. Acidic mucins, mainly sialomucins, constitute the major secretory component in prostatic adenocarcinomas, and our results show that the O-acylation of these sialoglycoproteins inversely correlates with tumor differentiation. Well-differentiated and moderately differentiated tumors are not O-acylated, whereas the poorly differentiated ones characteristically have O-acylated sialomucins in C9. Adenocarcinomas of the colloid type, thought to bear a poor prognosis, are the most heavily O-acylated.

Acetylation↗
PubMed1987

Influence of sialomucin at the resection margin on local tumour recurrence and survival of patients with colorectal cancer: a multivariate analysis.

In a multicentre prospective trial 358 patients undergoing curative surgery for colorectal cancer were followed for a median 18.0 months (+/- 7.2 months). The presence or absence of sialomucin in either resection margin was studied using the high iron diamine-alcian blue stain. There was evidence of excess sialomucin at one or other resection margin in 106 patients (29.6 per cent). Apart from sigmoid carcinomas occurring more often in the sialomucin positive group, there were no significant differences in any histological or clinical parameters between groups. Survival analysis for the events 'death', 'local recurrence', and 'all recurrence' was undertaken using the Cox regression model. The best prognostic variables selected in a stepwise fashion for death and all recurrence were 'Dukes' classification', 'sialomucin present' and 'histological differentiation'. The best prognostic variables selected for local recurrence were 'sialomucin present', 'Dukes' classification' and 'histological differentiation'. Sialomucin in a resection margin is an important independent prognostic variable for the development of local tumour recurrence and of subsequent survival for patients with colorectal carcinoma.

Aged↗
PubMed1986

Sialomucins at resection margin and likelihood of recurrence in colorectal carcinoma.

Oncogenic transformation of colonic epithelium is accompanied by changes in surface carbohydrate, notably an increased secretion of sialomucins at the expense of the normally predominant sulphomucins. In a multicentre prospective trial the correlation between the presence of sialomucins at the resection margin and the subsequent development of local recurrence was studied in 250 patients who had undergone "curative" resection for colorectal carcinoma with a mean follow up period of 14 months. Nineteen of 70 patients (27.1%) with a sialomucin predominant pattern at either resection margin developed local recurrence compared with 15 of 180 patients (8.3%) with a mixed or sulphomucin predominant pattern (p less than 0.01). Increased sialomucin staining at the resection margins was associated with reduced survival in these patients (p less than 0.01). At a mean of 14 months of follow up 153 patients (85%) were alive in the sulphomucin group and 53 patients (76%) were alive in the sialomucin group. Regression analysis predicted five year survivals of 32.8% and 18.9% for the sulphomucin and sialomucin groups respectively. Abnormal mucus production at the resection margin in patients treated for colorectal carcinoma appears to identify those with a higher risk of local recurrence and reduced survival.

Aged↗
PubMed1992

Sialomucin in middle ear cholesteatoma perimatrix.

Mucosubstance histochemistry of human middle ear cholesteatoma revealed that sialomucins are abundant and sulfomucins present in small amounts in the glandlike structures of the cholesteatoma perimatrix. Based on the study, various glycoproteins were injected into the dermis of the external ear canal and infiltrated into the tympanic membranes of guinea pigs. Tympanic membranes were obtained 7 days later and light- and electron-microscopically studied. Injection of a sialomucin from bovine submaxillary gland resulted in marked proliferation of epidermis and degeneration of the lamina propria. Asialomucin prepared from sialomucin by hydrolysis produced mild thickening of the epidermis but the lamina propria was not degenerated. Fetuin and bovine serum albumin did not cause proliferation of the epidermis. Cholesterol granuloma formed in some of the specimens injected with sialomucin. The presence of sialomucin in cholesteatoma perimatrix and these experimental studies using tympanic membranes of guinea pigs suggests that sialomucins participate in the proliferation of epidermis and degeneration of subepidermal connective tissue in human middle ear cholesteatoma.

Animals↗
PubMed1989

Complexity of MAM-6, an epithelial sialomucin associated with carcinomas.

The complexity of epithelial sialomucins was investigated by immunoprecipitation and membrane immunofluorescence, using monoclonal antibodies (MAbs) against MAM-6 and other sialomucins. MAbs against MAM-6 immunoprecipitated from a variety of sources either one or two sialylated glycoproteins with apparent molecular weights of over 400,000 under reducing as well as nonreducing conditions. The electrophoretic mobility of each MAM-6 glycoprotein as isolated from serum, milk, and cell lines of different individuals showed considerable variation. The differences in molecular weight of the MAM-6 glycoproteins were also reflected at the level of MAM-6 precursors which are less heavily glycosylated. Therefore, large differences in apparent molecular weight (150,000 and over) are most likely due to a variable protein backbone. We used this molecular polymorphism to prove that 11 MAbs against different sialomucins, obtained from various investigators, precipitated sialomucins generated from common precursor molecules. The pattern of reactivity of the MAbs with carcinoma cell lines was complex. All but the two MAbs, directed against putative carbohydrate epitopes, immunoprecipitated the precursor molecule from each cell line. However, some of them were unable to immunoprecipitate the mature form of MAM-6 from these cell lines. These results indicate that those epitopes are masked, probably due to cell line- or possibly cell type-dependent variations in glycosylation of the epithelial sialomucin. Even within a single cell line mature molecules with different epitopes were observed. The differential reactivity of the MAbs was confirmed by membrane immunofluorescence. These results show that MAM-6 belongs to a family of epithelial sialomucins with a polymorphic protein backbone and extensive variation in glycosylation.

Antibodies, Monoclonal↗
PubMed1994

Differences in terminal carbohydrate structures of sialomucin in the murine nasal cavity.

Terminal carbohydrate structures of sialomucin in the murine nasal cavity were characterized by means of lectin histochemistry. Two kinds of biotinylated lectins (Maackia amurensis agglutinin and Sambucus nigra agglutinin), which recognize sialic acid residues, showed marked differences in their respective labeling patterns when used as epithelial probes. Maackia amurensis agglutinin labeled the epithelial goblet cells, Bowman's glands, and all cell surfaces of both olfactory and respiratory epithelium. In contrast, Sambucus nigra agglutinin labeled cell surfaces and Bowman's glands in the murine olfactory epithelium, but did not label the murine respiratory epithelium. These results indicate that sialomucin in the murine nasal cavity has two different terminal carbohydrate structures. Our data show that sialomucin in the murine respiratory epithelium has a Neu5Ac(alpha 2-3)Gal sequence, while sialomucin in the murine olfactory epithelium has both alpha 2-3 and alpha 2-6 binding sequences. These results suggest that different carbohydrate structures of sialomucin in the nasal cavity may reflect differences in susceptibility to bacterial colonization and viral infection between respiratory and olfactory epithelium, and influence rheological properties of nasal secretion.

Animals↗
PubMed1985

Sialomucins in the assessment of dysplasia and cancer-risk patients with ulcerative colitis treated with colectomy and ileo-rectal anastomosis.

The clinical notes and histology of 374 patients treated by colectomy and ileo-rectal anastomosis for ulcerative colitis were reviewed. Only those with definite diagnosis of ulcerative colitis and follow-up rectal biopsies were included (171 cases). Morphology and patterns of mucin secretion were investigated to assess whether abnormal mucin with predominance of sialomucins is a useful indicator of malignancy-risk. Carcinoma has developed in six patients and 'precancer' in seven. The results show coexistence of dysplasia and sialomucin even in the absence of inflammation in all but three biopsies; in contrast the presence of both dysplasia and normal mucin profile was found in less than 1%. A significant correlation was noted between an inflamed mucosa and the development of cancer or precancer, the presence of sialomucins and the appearance of dysplasia. Sialomucins showed a greater sensitivity in detecting cancer than dysplasia (75% versus 30%). However, dysplasia was notably more specific (94% compared with 50%), hence its greater predictive value as indicator of malignancy (50% as against 15% for a positive sialomucin result). Mucin stains on routine fixed paraffin-embedded tissue provide a simple screening method to sharpen the assessment of dysplasia and cancer-risk in patients with ulcerative colitis despite the limitations referred to above. The lack of definite evidence of dysplasia in four patients who developed malignancy without premalignant changes in the rectal biopsies emphasises the need for frequent multiple biopsies in patients with an ileo-rectal anastomosis for ulcerative colitis.

Biopsy↗
PubMed1992

Molecular cloning of the transmembrane component of the 13762 mammary adenocarcinoma sialomucin complex. A new member of the epidermal growth factor superfamily.

Ascites sublines of the 13762 rat mammary adenocarcinoma have a cell surface sialomucin complex composed of the sialomucin ascites sialoglycoprotein-1 (ASGP-1) and the membrane-associated glycoprotein ASGP-2. The sialomucin complex is synthesized as a high M(r) precursor, pre-sialomucin complex (pSMC-1). To characterize the structure of the membrane-associated component of this complex, a lambda gt11 cDNA expression library was constructed using mRNA from 13762 rat mammary adenocarcinoma cells and screened with polyclonal antibody against ASGP-2. The strongest antibody-binding clone, designated lambda ASGP2.9-1, had a 1.3-kilobase (kb) insert, and hybridized to a 9-kb transcript in 13762 cell mRNA. The large size of this transcript was expected, since the estimated molecular mass of pSMC-1 is greater than 250 kDa. To obtain the full sequence of ASGP-2, a longer cDNA (5.4 kb), designated pASGP1/2.1, was subsequently cloned by screening a plasmid library with an oligonucleotide complementary to the 5' end of the phage insert. The amino acid sequence derived from nucleotide sequence of pASGP1/2.1 showed a 12-amino acid identity with amino acid sequence obtained from the NH2 terminus of ASGP-2, indicating the entire ASGP-2 coding region was included in the cDNA. Furthermore, an 18-amino acid identity with the NH2 terminus of a 6-kDa CNBr fragment of ASGP-2 was also observed in the cDNA sequence. The polypeptide contains several distinct domains, including a hydrophobic transmembrane domain, a short (20 residue) COOH-terminal cytoplasmic tail, and a large extracellular domain with 24 potential N-glycosylation sites. These properties correspond to features of ASGP-2 and pSMC-1 predicted by previous biochemical studies. Most interestingly, the extracellular domain contains two cysteine-rich sequences, each of which has a segment with strong similarities to proteins with epidermal growth factor activity. Since our recent studies show that ASGP-2 can modulate epidermal growth factor receptor phosphorylation activity, these results provide structural evidence to support the role of the heterodimeric sialomucin complex as a bifunctional modulator of cellular interactions and cell proliferation.

Adenocarcinoma↗
PubMedDate not supplied

Structural and functional aspects of tumor cell sialomucins.

Sialomucins are abundant on the surfaces of certain ascites tumor cells and have been implicated in the escape of tumors from immune destruction and metastasis. They are large, highly glycosylated glycoproteins which are rich in serine and threonine and have a variety of 0-linked oligosaccharides. The sialomucin (ASGP-1) or 13762 rat mammary adenocarcinoma ascites cells represents more than 0.5% of the total cell protein and can be isolated from cell membranes by centrifugation in 4 M guanidine hydrochloride-cesium chloride. ASGP-1 can also be isolated from membranes or cells by nonionic detergent extraction as a 1:1 complex with a second glycoprotein ASGP-2. Studies with the fluorescent lectins peanut agglutinin, which binds ASGP-1, and Concanavalin A, which binds ASGP-2, indicate that the glycoproteins are present at the cell surface as a complex. ASGP-1 is shed into cell culture medium or ascites fluid, apparently by a proteolytic cleavage mechanism. 13762 ascites cells grown in culture or as solid tumors lose their ASGP-1. The sialomucin reappears with extensive passage of the tumor cells in ascites form. Studies on the biosynthesis of ASGP-1 indicate that carbohydrate is being added over nearly the entire period of transit of ASGP-1 from the site of polypeptide synthesis to the plasma membrane. The negatively charged, rod-like structure of the sialomucins suggests that they may play a role in inhibiting recognition or binding processes necessary for the immune destruction of these tumor cells.

Animals↗
PubMed1990

Predominance of sialomucin secretion in malignant and premalignant pancreatic lesions.

Sialomucin and sulphomucin-secreting cells were studied in the normal and pathologic human pancreas with the high iron diamine-alcian blue technique which allows differentiation between the two types of mucin. In six normal autopsy pancreata, only sulphomucin was found. In benign lesions of either calcifying chronic pancreatitis (seven cases) or obstructed chronic pancreatitis (six cases), sulphomucins were widely predominant. In contrast, malignant lesions (pancreatic adenocarcinoma [12 cases], cystadenocarcinoma [two cases]) or premalignant lesions (mucinous cystadenoma [one case], ductectatic mucinous cystadenoma [four cases], villous adenoma of the main pancreatic duct [two cases]) showed a predominant sialomucin secretion, except for three poorly differentiated pancreatic carcinomas that did not show mucin staining. The sialomucin positivity was not observed at distance from the malignant lesions. In one case of benign enteroid cyst, sulphomucins predominated. These findings indicate a preponderance of sialomucin secretion in malignant or premalignant pancreatic lesions.

Chronic Disease↗
PubMed2006

Nepmucin, a novel HEV sialomucin, mediates L-selectin-dependent lymphocyte rolling and promotes lymphocyte adhesion under flow.

Lymphocyte trafficking to lymph nodes (LNs) is initiated by the interaction between lymphocyte L-selectin and certain sialomucins, collectively termed peripheral node addressin (PNAd), carrying specific carbohydrates expressed by LN high endothelial venules (HEVs). Here, we identified a novel HEV-associated sialomucin, nepmucin (mucin not expressed in Peyer's patches [PPs]), that is expressed in LN HEVs but not detectable in PP HEVs at the protein level. Unlike conventional sialomucins, nepmucin contains a single V-type immunoglobulin (Ig) domain and a mucin-like domain. Using materials affinity-purified from LN lysates with soluble L-selectin, we found that two higher molecular weight species of nepmucin (75 and 95 kD) were decorated with oligosaccharides that bind L-selectin as well as an HEV-specific MECA-79 monoclonal antibody. Electron microscopic analysis showed that nepmucin accumulates in the extended luminal microvillus processes of LN HEVs. Upon appropriate glycosylation, nepmucin supported lymphocyte rolling via its mucin-like domain under physiological flow conditions. Furthermore, unlike most other sialomucins, nepmucin bound lymphocytes via its Ig domain, apparently independently of lymphocyte function-associated antigen 1 and very late antigen 4, and promoted shear-resistant lymphocyte binding in combination with intercellular adhesion molecule 1. Collectively, these results suggest that nepmucin may serve as a dual-functioning PNAd in LN HEVs, mediating both lymphocyte rolling and binding via different functional domains.

Amino Acid Sequence↗
PubMed1995

Immunohistochemical detection of O-acetylated sialomucins in intestinal metaplasia and carcinoma of the stomach.

Eighty-two selected gastric mucosal biopsy or resection specimens were stained both conventionally, to classify subtypes of intestinal metaplasia and carcinoma, and immunohistochemically with a mouse monoclonal antibody (MMM-17), raised against normal human colonic mucin, which has an affinity for di- and/or tri-O-acetylated sialomucin. The aims of the study were to reassess the prevalence of O-acetylated sialomucins in normal, metaplastic and carcinomatous gastric mucosa and to investigate whether the production of these mucins by intestinal metaplasia is related to its associated mucosal pathology. O-acetylated sialomucins were not seen in normal mucosa. They were, however, prevalent in all sub-types of metaplastic (64.8%) and carcinomatous (42.9%) mucosa. Type 1 intestinal metaplasia was significantly more likely to contain this type of mucin if Helicobacter pylori infection was identifiable in the adjacent gastric mucosa (81.0% v. 38.5%, P < 0.025). Type 3 showed a similar, albeit nonsignificant, relationship (100% v. 62.5%). O-acetylated sialomucins are, therefore, much more prevalent in gastric intestinal metaplasia and carcinoma than previously recognized by conventional staining techniques. The production of this type of mucin by intestinal metaplasia may reflect an adaptive response to alterations in the luminal environment such as an increase in bacterial content.

Acetylation↗
PubMed1993

Distribution of O-acetylated sialomucin in the normal and diseased gastrointestinal tract shown by a new monoclonal antibody.

AIMS: To produce and characterise a monoclonal antibody specific for O-acetylated sialomucin and to assess its use in immunohistochemistry on a panel of normal and diseased intestinal tissue samples. METHODS: Mouse monoclonal antibodies were developed following immunisation with highly purified human colonic mucin. One of these (MMM-17) showed strong binding to mucin throughout the normal colon with relative lack of binding to colon cancer tissue. The binding epitope of MMM-17 was then characterised by screening for agglutination activity against a panel of human and animal erythrocytes and by assessment of its binding to a range of normal and chemically treated slot blotted mucins. Further immunohistochemical studies were then performed on formalin fixed, normal, and diseased human intestinal samples. RESULTS: Binding of MMM-17 to slot blotted human colonic mucin was reduced by 38 (SD 14%) (n = 4) by alkali treatment of the mucin, sequential alkali and sialidase treatment completely abolished binding. Sialidase treatment alone, however, caused only an 11 (11%) reduction in binding. MMM-17 failed to agglutinate any human, rabbit, rat or mouse erythrocytes. These findings were compatible with specificity of MMM-17 for sialomucins O-acetylated at the C-7 or C-8 positions on the sialic acid. Strong staining by MMM-17 was found in all goblet cells throughout all 40 normal colonic and rectal samples studied, but staining was absent in seven of 13 colorectal carcinomas. Normal duodenum (n = 16) and normal ileum (n = 3) all showed occasional positive goblet cells. The normal gastric antral mucosa was generally negative B MMM-17, but in all of 15 cases of gastritis with intestinal metaplasia the metaplastic glands were strongly positive for MMM-17. CONCLUSION: Monoclonal antibody MMM-17 has specificity for O-acetylated sialomucins and its binding depends both on the position of O-acetylation and on the adjacent oligosaccharide structure. Preliminary studies using the antibody on archival tissue samples support the previous reports of reduced O-acetylation in colon cancer demonstrated by indirect histochemistry and show the neo-formation of O-acetylated sialomucin in intestinal metaplasia in the stomach.

Animals↗
PubMed1998

Quantitative analysis of mRNA encoding MUC1, MUC2, and MUC5AC genes: a correlation between specific mucin gene expression and sialomucin expression in non-small cell lung cancer.

The expression of mucins is important for tumor invasiveness and metastasis. In our previous report (Am. J. Respir. Crit. Care Med. 1997; 155:1419-1427), non-small cell lung cancers bearing sialomucin expression tended to relapse earlier than those without sialomucin. However, it remained unclear whether the expression of sialomucin in lung cancer is caused by an abnormal glycosylation process or by the expression of a specific mucin gene product. To address this problem, we established a modified quantitative competitive polymerase chain reaction (QC-PCR) analysis. RNA internal standards of MUC1, MUC2, and MUC5AC non-tandem repeat sequences were constructed, and known copy numbers of mucin RNA internal standards were introduced into reverse transcription-polymerase chain reactions (RT-PCR) for each mucin gene in order to compete with native mucin gene RNA during the reaction. The RNA of Gbeta-like gene (a housekeeping gene) was used as internal control for the RNA analysis. Twenty-five lung cancer tissues (13 adenocarcinomas and 12 squamous cell carcinomas) were used for analysis. Mann-Whitney rank sum test was applied to compare the expression amounts of different mucin genes in tissues. The results revealed that adenocarcinoma expressed higher amounts of MUC5AC gene than did squamous cell carcinoma (P = 0.03). The expression amount of MUC5AC correlated positively with the expression status of sialomucin (P = 0.012). Further studies are anticipated to elucidate the underlying mechanism contributing to this phenomenon.

Adenocarcinoma↗