Mucin glycoproteins in neoplasia

Immunohistochemical analysis of colorectal cancer with gastric phenotype: claudin-18 is associated with poor prognosis

Claudin-18 plays a key role in constructing tight junctions, and altered claudin-18 expression has been documented in various human malignancies; however, little is known about the biological significance of claudin-18 in colorectal cancer (CRC). The aim of this study is to investigate the significance of claudin-18 expression in CRC and its association with clinicopathological factors. We performed clinicopathological analysis of claudin-18 expression in a total of 569 CRCs by immunohistochemistry. Moreover, we investigated the association between claudin-18 and various markers including gastric/intestinal phenotype (MUC5AC, MUC6, MUC2 and CD10), CDX2, claudin-3, claudin-4, p53 and Ki-67. Claudin-18 expression was detected in 21 of the 569 CRCs (4%) and was seen exclusively on the cell membrane. Positive expression of claudin-18 showed a significant correlation with positive expression of MUC5AC (P < 0.0001) and negative expression of CDX2 (P= 0.0013). The prognosis of patients with positive claudin-18 expression was significantly poorer than in negative cases (P= 0.0106). Multivariate analysis revealed that T grade, M grade and claudin-18 expression were independent predictors of survival in patients with CRC. We revealed that claudin-18 expression correlates with poor survival in patients with CRC and is associated with the gastric phenotype.

Interaction between circulating galectin-3 and cancer-associated MUC1 enhances tumour cell homotypic aggregation and prevents anoikis

Background

Formation of tumour cell aggregation/emboli prolongs the survival of circulating tumour cells in the circulation, enhances their physical trapping in the micro-vasculature and thus increases metastatic spread of the cancer cells to remote sites.

Results

It shows here that the presence of the galactoside-binding galectin-3, whose concentration is markedly increased in the blood circulation of cancer patients, increases cancer cell homotypic aggregation under anchorage-independent conditions by interaction with the oncofetal Thomsen-Friedenreich carbohydrate (Galβ1,3GalNAcα-, TF) antigen on the cancer-associated transmembrane mucin protein MUC1. The galectin-3-MUC1 interaction induces MUC1 cell surface polarization and exposure of the cell surface adhesion molecules including E-cadherin. The enhanced cancer cell homotypic aggregation by galectin-MUC1 interaction increases the survival of the tumour cells under anchorage-independent conditions by allowing them to avoid initiation of anoikis (suspension-induced apoptosis).

Conclusion

These results suggest that the interaction between free circulating galectin-3 and cancer-associated MUC1 promotes embolus formation and survival of disseminating tumour cells in the circulation. This provides new information into our understanding of the molecular mechanisms of cancer cell haematogenous dissemination and suggests that targeting the interaction of circulating galectin-3 with MUC1 in the circulation may represent an effective therapeutic approach for preventing metastasis.

RNA interference suppression of mucin 5AC (MUC5AC) reduces the adhesive and invasive capacity of human pancreatic cancer cells

BACKGROUND

MUC5AC is a secretory mucin normally expressed in the surface muconous cells of stomach and bronchial tract. It has been known that MUC5AC de novo expression occurred in the invasive ductal carcinoma and pancreatic intraepithelial neoplasm with no detectable expression in normal pancreas, however, its function remains uncertain. Here, we report the impact of MUC5AC on the adhesive and invasive ability of pancreatic cancer cells.

METHODS

We used two MUC5AC expressing cell lines derived from human pancreatic cancer, SW1990 and BxPC3. Small-interfering (si) RNA directed against MUC5AC were used to assess the effects of MUC5AC on invasion and adhesion of pancreas cancer cells in vitro and in vivo. We compared parental cells (SW1990 and BxPC3) with MUC5AC suppressed cells by si RNA (si-SW1990 and si-BxPC3).

RESULTS

MUC5AC was found to express in more than 80% of pancreatic ductal carcinoma specimens. Next we observed that both of si-SW1990 and si-BxPC3 showed significantly lower adhesion and invasion to extracellular matrix components compared with parental cell lines. Expression of genes associated with adhesion and invasion including several integerins, matrix metalloproteinase (MMP) -3 and vascular endothelial growth factor (VEGF) were down-regulated in both MUC5AC suppressed cells. Furthermore, production of VEGF and phosphorylation of VEGFR-1 were significantly reduced by MUC5AC down regulation. Both of si-SW1990 and si-BxPC3 attenuated activation of Erk1/2. In vivo, si-SW1990 did not establish subcutaneous tumor in nude mice.

CONCLUSIONS

Knockdown of MUC5AC reduced the ability of pancreatic cancer cells to adhesion and invasion, suggesting that MUC5AC might contribute to the invasive motility of pancreatic cancer cells by enhancing the expression of integrins, MMP-3, VEGF and activating Erk pathway.

A comprehensive analysis of common genetic variation in MUC1, MUC5AC, MUC6 genes and risk of stomach cancer

OBJECTIVE

MUC1, MUC5AC, and MUC6 are main constituents of the mucus barrier in the stomach, which protects the underlying epithelium from acid, proteases, mechanical trauma, and pathogenic microorganisms. Accumulating evidence implicates potential roles of MUC1, MUC5AC, and MUC6 genetic variation in the development of stomach cancer.

METHODS

We evaluated the relationship between common genetic variations in these genes and stomach cancer risk, using an LD-based tagSNP approach in a population-based case-control study conducted in Warsaw, Poland, during 1994-1996. We genotyped 6, 8, and 14 tagSNPs in MUC1, MUC5AC, and MUC6 genes, respectively, among 273 cases newly diagnosed with stomach cancer and 377 controls.

RESULTS

Each of the six tagSNPs tested across the MUC1 region showed statistically significant associations with an increased risk of stomach cancer. Carriers of the haplotype ACTAA rare alleles of rs4971052, rs4276913, rs4971088, rs4971092, and rs4072037 had a nearly doubled risk (OR = 1.93, 95% CI = 1.49-2.48) compared to the referent haplotype GTAAG. Out of the eight tagSNPs across MUC5AC region, only minor allele of rs868903 was significantly associated with an increased risk of stomach cancer (OR = 1.80, 95% CI = 1.22-2.63).

CONCLUSIONS

Overall, our data provide evidence that some common variations in MUC1 and MUC5AC genes contribute to an elevated risk of stomach cancer. Further studies are needed to confirm these novel findings.

An O-glycosyltransferase promotes cell adhesion during development by influencing secretion of an extracellular matrix integrin ligand

Protein secretion and localization are crucial during eukaryotic development, establishing local cell environments as well as mediating cell interactions, signaling, and adhesion. In this study, we demonstrate that the glycosyltransferase, pgant3, specifically modulates integrin-mediated cell adhesion by influencing the secretion and localization of the integrin ligand, Tiggrin. We demonstrate that Tiggrin is normally O-glycosylated and localized to the basal matrix where the dorsal and ventral cell layers adhere in wild type Drosophila wings. In pgant3 mutants, Tiggrin is no longer O-glycosylated and fails to be properly secreted to this basal cell layer interface, resulting in disruption of integrin-mediated cell adhesion in the wing. pgant3-mediated effects are dependent on enzymatic activity, as mutations that form a stable protein yet abrogate O-glycosyltransferase activity result in Tiggrin accumulation within the dorsal and ventral cells comprising the wing. Our results provide the first in vivo evidence for the role of O-glycosylation in the secretion of specific extracellular matrix proteins, thus altering the composition of the cellular "microenvironment" and thereby modulating developmentally regulated cell adhesion events. As alterations in cell adhesion are a hallmark of cancer progression, this work provides insight into the long-standing association between aberrant O-glycosylation and tumorigenesis.

Role of the Epstein-Barr virus-encoded latent membrane protein-1, LMP1, in the pathogenesis of nasopharyngeal carcinoma

Although frequently expressed in Epstein-Barr virus (EBV)-positive malignancies, the contribution of the oncogenic latent membrane protein-1 (LMP1) to the pathogenesis of nasopharyngeal carcinoma remains to be fully defined. As a key effector in EBV-driven B-cell transformation in vitro, LMP1 also displays oncogenic properties in rodent fibroblasts, and exhibits similar effects in epithelial cells. LMP1 functions as a viral mimic of the TNFR family member, CD40, engaging a plethora of signaling pathways including: NF-kappaB, JNK/p38 (SAPK), PI3-kinase and ERK-MPK. The constitutive activation of these pathways appears central in the ability of LMP1 to induce multiple morphological and phenotypic alterations. Here we review the effects of LMP1 on epithelial cell growth transformation, and its putative role in the pathogenesis of nasopharyngeal carcinoma, focusing on key areas of proliferation, survival, cell motility and invasion.

Heparin as an inhibitor of cancer progression

Heparin is frequently used in the treatment of cancer-associated thromboembolism. Accumulating clinical evidence indicates that cancer patients treated with unfractionated and low-molecular weight heparin (LMWH) survive longer than patients treated by other anticoagulants, especially patients in the early stage of the disease. Experimental analysis from a number of animal models constantly provides evidence for the ability of heparin to attenuate metastasis. The non-anticoagulant activity of heparin on metastasis includes the ability to inhibit cell-cell-interaction through blocking of P- and L-selectin, to inhibit extracellular matrix protease heparanase, and to inhibit angiogenesis. This chapter summarizes current experimental evidence on the biology of heparin during cancer progression, with the focus on potential mechanism of heparin antimetastatic activity.

Mucins in ovarian cancer diagnosis and therapy

Ovarian cancer is the most lethal gynecologic malignancy and the five-year survival rate is only 35% after diagnosis. Epithelial ovarian cancer is a highly metastatic disease characterized by widespread peritoneal dissemination and ascites. The death incidences from ovarian cancer could be significantly lowered by developing new methods for the early diagnosis and treatment of this fatal disease. Several potential markers have been identified recently. However, mucins are the most promising markers for ovarian cancer diagnosis. Mucins are large extracellular, heavily glycosylated proteins and their aberrant expression has been implicated in the pathogenesis of a variety of cancers, including ovarian cancer. This review will summarize known facts about the pathological and molecular characteristics of ovarian cancer, the current status of ovarian cancer markers, as well as general information about mucins, the putative role of mucins in the progression of ovarian cancer and their potential use for the early diagnosis and treatment of this disease.

A new model for the presentation of tumor-associated antigens and the quest for an anticancer vaccine: a solution to the synthesis challenge via ring-closing metathesis

Fully synthetic, carbohydrate-based antitumor vaccine candidates have been synthesized in highly clustered modes. Multiple copies of tumor-associated carbohydrate antigens, Tn and STn, were assembled on a single cyclic peptide scaffold in a highly convergent manner. Ring-closing metathesis-mediated incorporation of an internal cross-linker was also demonstrated. In particular, this rigidified cross-linked construct would enhance a cluster-recognizing antibody response by retaining an appropriate distance between glycans attached to the peptide platform. Details of the design and synthesis of highly clustered antigens are described herein.

Current status of mucins in the diagnosis and therapy of cancer

Mucins are the most abundant high molecular weight glycoproteins in mucus. Their nature and glycosylation content dictates the biochemical and biophysical properties of viscoelastic secretions, pointing out an important role in diverse biological functions, such as differentiation, cell adhesions, immune responses, and cell signaling. Mucins are expressed in tubular organs by specialized epithelial cells in the body. Their aberrant expression is well documented in a variety of inflammatory or malignant diseases. From a prognosis point of view, their expression and alterations in glycosylation are associated with the development and progression of malignant diseases. Therefore, mucins can be used as valuable markers to distinguish between normal and disease conditions. Indeed, this alteration in glycosylation patterns generates several epitopes in the oligosaccharide side chains that can be used as diagnostic and/or prognostic markers. Furthermore, these characteristic tumor-associated epitopes are extensively used as appropriate immunotargets of malignant epithelial cells. Therefore, in an effort to detect and treat cancer at the earliest stage possible, mucins are analyzed as potential markers of disease for diagnosis, progression, and for therapeutic purposes. In this review, we focused on the current status of the distribution of mucins in normal and pathologic conditions and their clinical use both in cancer diagnosis and therapeutics treatments.

MUC2 mucin is a major carrier of the cancer-associated sialyl-Tn antigen in intestinal metaplasia and gastric carcinomas

Changes in mucin protein expression and in glycosylation are common features in pre-neoplastic lesions and cancer and are therefore used as cancer-associated markers. De novo expression of intestinal mucin MUC2 and cancer-associated sialyl-Tn antigen are frequently observed in intestinal metaplasia (IM) and gastric cancer. However, despite that these antigens often co-localize, MUC2 has not been demonstrated to be a carrier of sialyl-Tn. By using the in situ proximity ligation assay (in situ PLA), we herein could show that MUC2 is a major carrier of the sialyl-Tn antigen in all IM cases and in most gastric carcinoma cases. The requirement by in situ PLA for the presence of both antigens in close proximity increases the selectivity compared to measurement of co-localization, as determined by immunohistochemistry. Identification of the mucin which is the carrier of a carbohydrate structure offers unique advantages for future development of more accurate diagnostic and prognostic markers.

Circulating galectin-3 promotes metastasis by modifying MUC1 localization on cancer cell surface

Adhesion of circulating tumor cells to the blood vessel endothelium is a critical step in cancer metastasis. We show in this study that galectin-3, the concentration of which is greatly increased in the circulation of cancer patients, increases cancer cell adhesion to macrovascular and microvascular endothelial cells under static and flow conditions, increases transendothelial invasion, and decreases the latency of experimental metastasis in athymic mice. These effects of galectin-3 are shown to be a consequence of its interaction with cancer-associated MUC1, which breaks the "protective shield" of the cell-surface MUC1 by causing MUC1 polarization, leading to exposure of smaller cell-surface adhesion molecules/ligands including CD44 and ligand(s) for E-selectin. Thus, the interaction in the bloodstream of cancer patients between circulating galectin-3 and cancer cells expressing MUC1 bearing the galectin-3 ligand TF (Galbeta1,3GalNAc-) promotes metastasis. This provides insight into the molecular regulation of metastasis and has important implications for the development of novel therapeutic strategies for prevention of metastasis.

Prognostic significance of the expression of MUC1 and collagen type IV in advanced gastric carcinoma

Background

Scirrhous gastric carcinoma is characterized by excessive deposition of collagen in the stroma. However, the clinical significance of this fibrosis of the stomach has not been clarified. The aim of this study was to examine the fibrotic mechanism in several histological types of gastric carcinoma, and the combination of MUC1 and collagen type IV as a possible predictor of patient survival.

Methods

One hundred and two paraffin-embedded specimens of gastric carcinoma were examined by immunohistochemical staining using monoclonal antibodies against collagen type IV and MUC1.

Results

Collagen type IV-positive expression was significantly associated with depth of wall penetration (P = 0·025) and stage (P = 0·023). There was a significant relationship between MUC1-positive expression and interstitial collagen type IV-positive expression (P = 0·035). Survival was shorter for patients with the combination of MUC1-positive expression and interstitial collagen type IV-negative expression than for those with other expression patterns.

Conclusion

In patients with differentiated-type advanced gastric carcinoma, the combination of MUC1-positive and interstitial collagen type IV-negative expression may be a marker of unfavourable prognosis.

Ligation of tumour-produced mucins to CD22 dramatically impairs splenic marginal zone B-cells

CD22 [Siglec-2 (sialic acid-binding, immunoglobulin-like lectin-2)], a negative regulator of B-cell signalling, binds to alpha2,6- sialic acid-linked glycoconjugates, including a sialyl-Tn antigen that is one of the typical tumour-associated carbohydrate antigens expressed on various mucins. Many epithelial tumours secrete mucins into tissues and/or the bloodstream. Mouse mammary adenocarcinoma cells, TA3-Ha, produce a mucin named epiglycanin, but a subline of them, TA3-St, does not. Epiglycanin binds to CD22 and inhibits B-cell signalling in vitro. The in vivo effect of mucins in the tumour-bearing state was investigated using these cell lines. It should be noted that splenic MZ (marginal zone) B-cells were dramatically reduced in the mice bearing TA3-Ha cells but not in those bearing TA3-St cells, this being consistent with the finding that the thymus-independent response was reduced in these mice. When the mucins were administered to normal mice, a portion of them was detected in the splenic MZ associated with the MZ B-cells. Furthermore, administration of mucins to normal mice clearly reduced the splenic MZ B-cells, similar to tumour-bearing mice. These results indicate that mucins in the bloodstream interacted with CD22, which led to impairment of the splenic MZ B-cells in the tumour-bearing state.

Cadherin-catenin adhesion system and mucin expression: a comparison between young and older patients with gastric carcinoma

BACKGROUND

Young patients are thought to develop gastric carcinomas with a molecular genetic profile that is distinct from that of gastric carcinomas occurring at a later age. The aim of this study was to compare the clinicopathological features and expression patterns of the markers E-cadherin and beta-catenin, and mucins (MUC1, MUC2, MUC5AC, and MUC6) in young and older patients.

METHODS

The clinicopathological features and overall survival data of 62 young patients (age <or=40 years) with gastric cancer were retrospectively reviewed from hospital records and compared with the data for 453 older patients (age >40 years). A tissue microarray method and immunohistochemistry were used in order to analyze marker expression in paraffin-embedded tissue blocks obtained from both groups.

RESULTS

The young group presented a higher percentage of diffuse-type tumors in comparison to the older group (P<0.01). The rates of positivity for E-cadherin and beta-catenin membranous expression patterns and mucin (MUC2, MUC5AC and MUC6) positivity were higher in the young group (P<0.01). Although young patients showed a lower frequency of alterations in marker expression and had significantly better survival rates than the older patients, neither age nor the marker expression pattern were found to be independent prognostic factors of survival. Only stage, tumor size, and tumor location persisted as prognostic factors for patients with gastric cancer.

CONCLUSION

Biological markers of cellular adhesion and gastric differentiation were differently expressed in young and older patients. Our findings support the hypothesis that young patients develop carcinomas with a different genetic pathway compared to the pathway of tumors occurring at a later age, and we suggest further investigations to assess the prognostic relevance of the markers to specific subgroups.

Collision-induced dissociation tandem mass spectrometry for structural elucidation of glycans

The complexity of glycans poses a major challenge for structure elucidation. Tandem mass spectrometry is currently an efficient and powerful technique for the structural characterization of glycans. Collision-induced dissociation (CID) is most commonly used, and involves first isolating the glycan ions of interest, translationally exciting them, and then striking them with inert target gas to fragment the precursor ions. The structural information of the glycan can be obtained from the fragment ions of the tandem MS spectra. In this chapter, sustained off-resonance irradiation-collision-induced dissociation (SORI-CID) implemented with matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI FT ICR MS) is demonstrated to be a useful analysis tool for structural elucidation of mucin-type O-glycans released from mucin glycoproteins. The mechanisms by which the glycans undergo fragmentations in the tandem mass analysis are also discussed.

Clinicopathological and prognostic significance of mucin phenotype in gastric cancer

BACKGROUND AND OBJECTIVES

Gastric and intestinal mucin phenotype cell markers are widely expressed in gastric carcinoma cells, irrespective of their tumor histological type. In the present study, we tried to reveal the clinicopathological significance of mucin phenotype in human gastric carcinomas. Moreover, we investigated the clinical significance of RUNX3 in association with mucin phenotype.

METHODS

The mucin expression of MUC5AC, MUC6, MUC2, and CD10 was evaluated in 97 gastric carcinomas by immunohistochemistry. Tumors were classified into gastric (G), gastric and intestinal mixed (GI), intestinal (I), and null (N) phenotype according to combination of mucin expression.

RESULTS

The rate of G, GI, I, and N phenotype was 40.0%, 38.1%, 10.3%, and 19.6%, respectively. Mucin phenotype was also significantly correlated with several clinicopathological findings. Patients with I phenotype had a significantly poorer prognosis than those with any other phenotypes. They also had a higher rate of postoperative liver metastasis. Multivariate analysis revealed that mucin phenotype was a significant independent prognostic factor. We suggested that Loss of RUNX3 expression might correlate with intestinal phenotype and postoperative outcome.

CONCLUSIONS

Mucin phenotype has a significant prognostic value and may be a useful marker for the treatment of human gastric carcinoma.

Recent insights into the biological roles of mucin-type O-glycosylation

In this special issue of the Glycoconjugate Journal focusing on glycosciences and development, we summarize recent advances in our understanding of the role of mucin-type O-glycans in development and disease. The presence of this widespread protein modification has been known for decades, yet identification of its biological functions has been hampered by the redundancy and complexity of the enzyme family controlling the initiation of O-glycosylation, as well as the diversity of extensions of the core sugar. Recent studies in organisms as diverse as mammals and Drosophila have yielded insights into the function of this highly abundant and evolutionarily-conserved protein modification. Gaining an understanding of mucin-type O-glycans in these diverse systems will elucidate crucial conserved processes underlying many aspects of development and homeostasis.

Glycoproteomic analyses of ovarian cancer cell lines and sera from ovarian cancer patients show distinct glycosylation changes in individual proteins

Ovarian cancer is difficult to diagnose in women because symptoms of the disease are often not noticed until the disease has progressed to an advanced untreatable stage. Although a serum test, CA125, is currently available to assist with monitoring treatment of ovarian cancer, this test lacks the necessary specificity and sensitivity for early detection. Therefore, better biomarkers of ovarian cancer are needed. A glycoprotein analysis approach was undertaken using high resolution Fourier transform ion cyclotron resonance mass spectrometry to analyze glycosylated proteins present in the conditioned media of ovarian cancer cell lines and in sera obtained from ovarian cancer patients and normal controls. In this study, glycosylated proteins were separated by gel electrophoresis, and individual glycoproteins were selected for glycosylation analysis and protein identification. The attached glycans from each protein were released and profiled by mass spectrometry. Glycosylation of a mucin protein and a large glycosylated protein isolated from the ES2 ovarian cancer cell line was determined to consist of mostly O-linked glycans. Four prominent glycoproteins of approximate 517, 370, 250, 163 kDa from serum samples were identified as two forms of apolipoprotein B-100, fibronectin, and immunoglobulin A1, respectively. Mass spectrometric analysis of glycans isolated from apolipoprotein B-100 (517 kD) showed the presence of small, specific O-linked oligosaccharides. In contrast, analysis of fibronectin (250 kD) and immunoglobulin A1 (163 kD) produced N-linked glycan fragments in forms that were sufficiently different from the glycans obtained from the corresponding protein band present in the normal serum samples. This study shows that not only a single protein but several are aberrantly glycosylated, and those abnormal glycosylation changes can be detected and may ultimately serve as glycan biomarkers for ovarian cancer.

Cathelicidin stimulates colonic mucus synthesis by up-regulating MUC1 and MUC2 expression through a mitogen-activated protein kinase pathway

Mucus forms the physical barrier along the gastrointestinal tract. It plays an important role to prevent mucosal damage and inflammation. Our animal study showed that antibacterial peptide 'cathelicidin' increased mucus thickness and prevented inflammation in the colon. In the current study, we examined the direct effect and mechanisms by which the peptide increased mucus synthesis in a human colonic cell line (HT-29). Human cathelicidin (LL-37) dose-dependently (10-40 microg/ml) and significantly stimulated mucus synthesis by increasing the D-[6-(3)H] glucosamine incorporation in the cells. Real-time PCR data showed that addition of LL-37 induced more than 50% increase in MUC1 and MUC2 mRNA levels. Treatment with MUC1 and MUC2 siRNAs normalized the stimulatory action of LL-37 on mucus synthesis. LL-37 also activated the phosphorylation of mitogen-activated protein (MAP) kinase in the cells. A specific inhibitor of the MAP kinase pathway, U0126, completely blocked the increase of MUC1 and MUC2 expression as well as mucus synthesis by LL-37. Taken together, LL-37 can directly stimulate mucus synthesis through activation of MUC1 and MUC2 expression and MAP kinase pathway in human colonic cells.

Synchronous orofacial granulomatosis and mucoepidermoid carcinoma: paraneoplastic syndrome or coincidence?

Some malignant neoplasias induce the appearance of local or systemic manifestations at distant sites, which can act as indicators of their presence in a process named paraneoplastic syndrome. Granulomatous reactions have already been described related to malignancies. This report describes a case of synchronous orofacial granulomatosis and mucoepidermoid carcinoma and discusses the significance of this association.

Down-modulation of B cell signal transduction by ligation of mucins to CD22

Epithelial cancer cells secrete mucins carrying carbohydrate antigens such as a sialyl-Tn antigen into cancer tissues and/or the bloodstream, in which mucins may interact with CD22 (Siglec-2). Mucins isolated from colon cancer cells and bovine submaxillary mucins bound to CD22 cDNA transfectants and a human B cell line, Daudi cell, and the binding of soluble recombinant CD22 to the mucins was confirmed by means of a plate assay. The binding specificity was demonstrated by the fact that the mucins bound to the recombinant CD22 with an intact ectodomain but not to that with a mutated ectodomain. Daudi cells were stimulated with anti-IgM F(ab')(2) in the presence or absence of mucins. Ligation of mucins to CD22 decreased the phosphorylation of CD22 and SHP-1 recruitment, and the phosphorylation of ERK-1/2 prominently. The in vivo effect of mucins on splenic B cells in the tumor-bearing state was investigated using mucin-producing (TA3-Ha) and non-producing (TA3-St) mammary adenocarcinoma-bearing mice. When fluorescence-labeled epiglycanins were administered to normal mice, a portion of them was taken up by the spleen and became associated with splenic B cells. We found that splenic B cells were reduced in TA3-Ha-bearing mice but not in TA3-St-bearing ones. These results suggest that in the tumor-bearing state a portion of the mucins in the bloodstream was taken up by the spleen and ligated to CD22 expressed on splenic B cells, which may have led to down-regulation of signal transduction.

DNA tumour viruses promote tumour cell invasion and metastasis by deregulating the normal processes of cell adhesion and motility

Approximately 15-20% of global cancer incidence is causally linked to viral infection, yet the low incidence of cancers in healthy infected individuals suggests that malignant conversion of virus-infected cells occurs after a long period as a result of additional genetic modifications. There are four families of viruses that are now documented to be involved in the development of human cancers which include members of the polyomavirus, hepadnavirus, papillomavirus and herpesvirus families. Although a number of these viruses are implicated in the aetiology of lymphomas or leukaemias, the vast majority are associated with malignancies of epithelial cells. In epithelial tissues, several classes of proteins are involved in maintaining tissue architecture, including those that promote cell-cell adhesion, and others, which mediate cell-matrix interactions. Proteins representative of all classes are frequently altered in malignant tumour cells that possess invasive and metastatic properties. Malignant tumour cells acquire mechanisms to degrade basement membranes and invade the underlying tissue. Many viruses encode proteins which engage signalling pathways that affect one or more of these mechanisms. It is believed that activation of these processes by chronic viral infection can, under certain circumstances, promote tumour cell invasion and metastasis. This review will take a brief look at the current knowledge of viral-induced alterations in cell motility and invasiveness in the context of tumour invasion and metastasis.

Alterations in mucin expression in ovarian mucinous tumors: immunohistochemical analysis of MUC2, MUC5AC, MUC6, and CD10 expression

The aim of this study was to evaluate the immunohistochemical expression of MUC2, MUC5AC, MUC6, and CD10 in ovarian mucinous adenoma (MA), mucinous borderline tumor (MB), and mucinous adenocarcinoma (MC), and to analyze the relationship between prognosis and these expressions. The expression of MUC2, MUC5AC, MUC6, and CD10 was evaluated by immunohistochemical analysis in 29 cases of MA, 29 cases of MB, and 26 cases of MC and scored based on the percentage of positive cells. Moreover, the ovarian mucinous tumors were classified into 4 phenotypes based on the staining patterns: intestinal, gastrointestinal, gastric, and unclassified patterns. The gastrointestinal pattern and the expression of MUC2 and CD10 increased from MA to MC. Conversely, the gastric pattern and MUC5AC expression decreased from MA to MC. Low MUC2 expression in MC was correlated with a better long-term survival rate. MUC2 expression in MC may be a useful predictor of the clinical outcome. The expression patterns of MUC2, MUC5AC, MUC6, and CD10 indicated that intestinal metaplasia may arise from the gastric-like epithelium in MA and that a close association exists between carcinogenesis and intestinal metaplasia in major ovarian mucinous tumors.

Aberrant expression of SOX2 upregulates MUC5AC gastric foveolar mucin in mucinous cancers of the colorectum and related lesions

Mucinous colorectal cancers are characterized by abundant production of intestinal goblet cell mucin, MUC2 and frequent ectopic expression of gastric foveolar mucin, MUC5AC. SOX2, an HMG-box transcription factor expressed in gastric mucosa but not in intestine is thought to play an important role in regulating transcription and expression of gastric differentiation related genes. Herein, we investigated the possible role of SOX2 in MUC5AC transcription and in the development of mucinous cancers. We observed good correlation between SOX2 and MUC5AC message levels in most colon cancer cell lines. SOX2 expression significantly transactivated MUC5AC promoter/reporter constructs in 3 of 5 colon cancer cell lines. We also examined SOX2 expression in normal stomach and colon, nonmucinous and mucinous colorectal cancers, serrated polyps and conventional adenomas using immunohistochemistry and in situ hybridization. SOX2 was expressed in the nuclei of both gastric foveolar cells and fundic glands by immunohistochemistry and in the cytoplasm by in situ hybridization. SOX2 was not expressed in normal colon but was strongly expressed in serrated polyps, mucinous and signet ring cell carcinomas, but rarely in nonmucinous carcinomas and tubular adenomas. Concordant expression of SOX2 with MUC5AC was observed in these lesions. Our results suggest that SOX2 is important in the upregulation of gastric foveolar mucin, MUC5AC in colorectal mucinous and signet ring cell carcinomas. In addition, the expression of both SOX2 and MUC5AC in serrated polyps supports the hypothesis that these polyps may be predominant precursors of mucinous and signet ring cell carcinomas of the colorectum.

The metastatic T-cell hybridoma antigen/P-selectin glycoprotein ligand 1 is required for hematogenous metastasis of lymphomas

Using variants of the murine BW5147 lymphoma cell-line, we have previously identified 3 monoclonal antibodies (MAbs) that discriminate between metastatic and nonmetastatic BW5147-derived T-cell hybridomas and lymphomas, as well as BW5147-unrelated T-lymphomas. These MAbs were reported to recognize an identical membrane-associated sialoglycoprotein, termed "metastatic T-cell hybridoma antigen" (MTH-Ag). Here, we document that the expression pattern of the MTH-Ag on metastatic and nonmetastatic BW5147 variants correlates with that of the P-selectin glycoprotein ligand 1 (PSGL-1), a sialomucin involved in leukocyte recruitment to sites of inflammation. Moreover, the MAbs against the MTH-Ag recognize PSGL-1 when it is transfected in MTH-Ag-negative BW5147 variants, suggesting that the MTH-Ag is PSGL-1. Overexpression of MTH-Ag/PSGL-1 in MTH-Ag-negative BW5147 variants did not affect their in vivo malignancy. Yet, down-regulation of MTH-Ag/PSGL-1 expression on metastatic, MTH-Ag-positive BW5147 variants, using an RNA interference (RNAi) approach, resulted, in a dose-dependent manner, in a significant reduction of liver and spleen colonization and a delay in mortality of the recipient mice upon intravenous inoculation. Collectively, these results demonstrate that, although MTH-Ag/PSGL-1 overexpression alone may not be sufficient for successful dissemination and organ colonization, MTH-Ag/PSGL-1 plays a critical role in hematogenous metastasis of lymphoid cancer cells.

The value of combined use of survivin, cytokeratin 20 and mucin 7 mRNA for bladder cancer detection in voided urine

OBJECTIVES

To evaluate the value of combined use of survivin, cytokeratin (CK) 20 and mucin (MUC) 7 mRNA in comparison with voided urine cytology in the detection of bladder cancer patients.

METHODS

One hundred and fifty three patients and 20 healthy volunteers were evaluated by RT-PCR for detecting survivin, CK-20 and MUC7 mRNA in voided urine before cystoscopy. The three markers and cytology were evaluated independently or in combinations.

RESULTS

The overall sensitivity and specificity were 90.4 and 94.7% for survivin, 82.6 and 97.4% for CK-20, 62.6 and 94.7% for MUC7 and 46.0 and 100% for voided urine cytology. Combined sensitivity of voided urine cytology with the three biomarkers together was higher than either combined sensitivity of voided urine cytology with one of the biomarkers or than that of the biomarker alone.

CONCLUSIONS

Combined use of the three markers can improve the sensitivity for detecting bladder cancer.

Targeting glycosylation pathways and the cell cycle: sugar-dependent activity of butyrate-carbohydrate cancer prodrugs

Short-chain fatty acid (SCFA)-carbohydrate hybrid molecules that target both histone deacetylation and glycosylation pathways to achieve sugar-dependent activity against cancer cells are described in this article. Specifically, n-butyrate esters of N-acetyl-D-mannosamine (But4ManNAc, 1) induced apoptosis, whereas corresponding N-acetyl-D-glucosamine (But4GlcNAc, 2), D-mannose (But5Man, 3), or glycerol (tributryin, 4) derivatives only provided transient cell cycle arrest. Western blots, reporter gene assays, and cell cycle analysis established that n-butyrate, when delivered to cells via any carbohydrate scaffold, functioned as a histone deacetylase inhibitor (HDACi), upregulated p21WAF1/Cip1 expression, and inhibited proliferation. However, only 1, a compound that primed sialic acid biosynthesis and modulated the expression of a different set of genes compared to 3, ultimately killed the cells. These results demonstrate that the biological activity of butyrate can be tuned by sugars to improve its anticancer properties.

Threonine utilization for synthesis of acute phase proteins, intestinal proteins, and mucins is increased during sepsis in rats

We hypothesized that the dietary threonine demand for the anabolic response may be increased more than that of other essential amino acids during sepsis. Using a flooding dose of either L-[1 -13C]valine or L-[U -13C]threonine, we measured valine and threonine utilization for syntheses of plasma proteins (minus albumin), and wall, mucosal, and mucin proteins of the small intestine in infected (INF; d 2 and d 6 of postinfection) and control pair-fed (PF) rats. At d 2, the protein absolute synthesis rate (ASR) of INF rats was 21% (mucins) to 41% (intestinal wall) greater than that of PF when measured using valine as tracer, and 45% (mucosa) to 113% (mucins) greater than that of PF when measured with threonine as tracer. Plasma protein ASR was higher in INF than in PF rats, reaching 5- to 6-fold the value of PF. The utilization of both amino acid tracers for the protein synthesis was significantly increased by the infection in all compartments studied. The daily increased absolute threonine utilization for protein synthesis in gut wall plus plasma proteins was 446 micromol/d compared with 365 micromol/d for valine, and it represented 2.6 times the dietary threonine intake of rats at d 2. Most changes in protein ASR and threonine utilization observed at d 6 of postinfection were limited. In conclusion, sepsis increased the utilization of threonine for the anabolic splanchnic response. Because this threonine requirement is likely covered by muscle protein mobilization, increasing the threonine dietary supply would be an effective early nutritional management for patients with sepsis.

Trousseau's syndrome: multiple definitions and multiple mechanisms

In 1865, Armand Trousseau noted that unexpected or migratory thrombophlebitis could be a forewarning of an occult visceral malignancy. An analysis by Sack and colleagues in 1977 extended the term Trousseau's syndrome to include chronic disseminated intravascular coagulopathy associated with microangiopathy, verrucous endocarditis, and arterial emboli in patients with cancer, often occurring with mucin-positive carcinomas. In recent times the term has been ascribed to various clinical situations, ranging all the way from these classic descriptions to any kind of coagulopathy occurring in the setting of any kind of malignancy. These multiple definitions of Trousseau's syndrome are partly the consequence of multiple pathophysiologic mechanisms that apparently contribute to the hypercoagulability associated with cancer. Even the classic syndrome probably represents a spectrum of disorders, ranging from exaggerated fluid-phased thrombosis dependent on prothrombotic agents such as tissue factor to a platelet- and endotheliumum-based selectin-dependent microangiopathy associated with mucin-producing carcinomas, along with thrombin and fibrin production. Also considered here are recent hypotheses about genetic pathways within tumor cells that might trigger these thrombotic phenomena, and the reasons why therapy with heparins of various kinds remain the preferred treatment, probably because of their salutary actions on several of the proposed pathologic mechanisms.

Selectin Blocking Activity of a Fucosylated Chondroitin Sulfate Glycosaminoglycan from Sea Cucumber

Heparin is an excellent inhibitor of P- and L-selectin binding to the carbohydrate determinant, sialyl Lewis(x). As a consequence of its anti-selectin activity, heparin attenuates metastasis and inflammation. Here we show that fucosylated chondroitin sulfate (FucCS), a polysaccharide isolated from sea cucumber composed of a chondroitin sulfate backbone substituted at the 3-position of the beta-D-glucuronic acid residues with 2,4-disulfated alpha-L-fucopyranosyl branches, is a potent inhibitor of P- and L-selectin binding to immobilized sialyl Lewis(x) and LS180 carcinoma cell attachment to immobilized P- and L-selectins. Inhibition occurs in a concentration-dependent manner. Furthermore, FucCS was 4-8-fold more potent than heparin in the inhibition of the P- and L-selectin-sialyl Lewis(x) interactions. No inhibition of E-selectin was observed. FucCS also inhibited lung colonization by adenocarcinoma MC-38 cells in an experimental metastasis model in mice, as well as neutrophil recruitment in two models of inflammation (thioglycollate-induced peritonitis and lipopolysaccharide-induced lung inflammation). Inhibition occurred at a dose that produces no significant change in plasma activated partial thromboplastin time. Removal of the sulfated fucose branches on the FucCS abolished the inhibitory effect in vitro and in vivo. Overall, the results suggest that invertebrate FucCS may be a potential alternative to heparin for blocking metastasis and inflammatory reactions without the undesirable side effects of anticoagulant heparin.

The oncofetal Thomsen-Friedenreich carbohydrate antigen in cancer progression

The oncofetal Thomsen-Friedenreich carbohydrate antigen (Galbeta1-3GalNAcalpha1-Ser/Thr TF or T antigen) is a pan-carcinoma antigen highly expressed by about 90% of all human carcinomas. Its broad expression and high specificity in cancer have attracted many investigations into its potential use in cancer diagnosis and immunotherapy. Over the past few years increasing evidence suggests that the increased TF occurrence in cancer cells may be functionally important in cancer progression by allowing increased interaction/communication of the cells with endogenous carbohydrate-binding proteins (lectins), particularly the members of the galactoside-binding galectin family. This review focuses on the recent progress in understanding of the regulation and functional significance of increased TF occurrence in cancer progression and metastasis.

Mucin biosynthesis: identification of the cis-regulatory elements of human C2GnT-M gene

Mucin glycan is the primary determinant of mucin functions. These functions are expanded by three branch structures, including core 2, core 4, and blood group I, which are synthesized by core 2 beta1,6 N-acetylglucosaminyltransferase-M (C2GnT-M). Alteration of C2GnT-M gene expression is expected to have a profound effect on mucin functions, which prompted us to study the regulation of this gene. Quantitative real-time PCR analysis of the expression of this gene in 24 human tissues and airway epithelial cells showed that this gene was expressed primarily in mucus-secretory tissues. 5' Rapid amplification of cDNA ends analysis, coupled with sequence alignment with human genome database, revealed that this gene was comprised of three exons and two introns. Northern blotting using exon 1 probe showed the presence of this exon in all transcripts, suggesting the presence of cis-regulatory elements in the proximal region upstream of and/or near the transcription initiation site (+1). Analysis of this DNA region (-417/+187) by a promoter-reporter transient transfection assay, coupled with serial deletion and linker scanning mutagenesis, revealed two positive regulatory regions, including -291/-282, and -62/-43. Further, the promoter activity was enhanced by all-trans retinoic acid (ATRA) and IL-13. Thus, the promoter region is specific to hC2GnT-M gene and subject to regulation by ATRA and IL-13. These cis-regulatory elements may be useful for construction of a mucus cell-specific vector for therapy of mucus hypersecretory diseases.

Overproduction of PGE2 in peripheral blood monocytes of gastrointestinal cancer patients with mucins in their bloodstream

When monocytes from healthy donors were cultured in the presence of sera from patients with gastrointestinal cancer, PGE2 production from the monocytes was elevated. Serum proteins were fractionated on Sepharose 4B and the inducing activity was found in the excluded fractions. By excluding some mucins from the serum, the inducing activity was reduced effectively. The activity was also reduced by adding binding inhibitors to the scavenger receptor. These results suggest that peripheral blood monocytes in epithelial cancer patients may be continuously stimulated by mucins in the bloodstream through the scavenger receptor, resulting in overproduction of PGE2.

Clinicopathological implications of immunohistochemically demonstrated mucin core protein expression in hepatocellular carcinoma

METHODS

We examined the expression of mucin core protein 1 (MUC1) immunohistochemically in 186 surgical specimens of histopathologically nonmucinous hepatocellular carcinoma (HCC) and compared the clinicopathological features in patients with MUC1-positive HCC (MUC1-positive group) with those in patients with MUC1-negative HCC (MUC1-negative group).

RESULTS

MUC1 immunoreactively was present in 85 of the 186 HCCs. Of the clinicopathological variables examined, the serum concentration of alpha-fetoprotein, tumor differentiation, bile duct invasion, lymph node metastasis, and cytokeratin 19 expression exhibited significant associations with MUC1 expression. Although cumulative and tumor-free survival rates were not different between the two groups, the percentage of patients with first recurrence of HCC in distant organs (distant metastasis) within 2 years after surgery was significantly higher in the MUC1-positive group than in the MUC1-negative group (P = 0.0104). The risk ratio of MUC1 positivity for this type of distant metastasis was 3.156 (95% confidence interval, 1.064-9.358).

CONCLUSIONS

In patients with MUC1-positive HCC, careful follow-up is necessary, not only for intrahepatic recurrence but also for distant metastasis, after the resection of primary HCC.

Diagnostic utility of mucin profile in fine-needle aspiration specimens of the pancreas: an immunohistochemical study with surgical pathology correlation

BACKGROUND

The cytologic differentiation between neoplastic and reactive/reparative processes in the endoscopic ultrasound-guided fine-needle aspirations (EUS-FNA) of the pancreas can be difficult. Malignant transformation of the pancreatic ductal epithelium changes the expression of apomucins. The goal of the current study was to determine an optimal immunohistochemical panel of mucin (MUC) antibodies that would allow the cytomorphologic distinction of pancreatic ductal adenocarcinoma and its differentiation from reactive/reparative processes and inadvertently sampled gastric and duodenal mucosa.

METHODS

Pancreatic EUS-FNA specimens performed on 351 patients were reviewed. Expression profiles of MUC1, 2, 5AC, and 6 were examined on 56 cell block sections and 26 follow-up pancreatectomy specimens.

RESULTS

MUC1 and 6 expression was found in nonneoplastic pancreatic samples, whereas there was an absence of expression of MUC2 and 5AC. MUC2 was detected in mucosal goblets cells of the duodenum, MUC6 in Brunner glands, and MUC5AC in gastric foveolar cells. MUC5AC expression in differentiating ductal adenocarcinomas from benign conditions demonstrated better operating characteristics than either MUC1 or MUC6. The apomucin expression pattern both in cytology and follow-up surgical pathology specimens was similar. In surgical pathology specimens, the panel of 3 antibodies, MUC1+/MUC2-/MUC5AC+, was noted in 15 of 17 ductal carcinomas (88.2%). In nonneoplastic pancreatic tissue, the expression panel MUC1+/MUC2-/MUC5AC- was observed in 14 of 17 (82.4%) cases. In cytology specimens, the combination of MUC1+/MUC2-/MUC5AC+ was noted in 21 of 30 ductal carcinoma cases (70.0%), 3 of 6 atypical cases (50%), and 1 of 1 suspicious for malignancy cases (100%). The combination MUC1+/MUC2-/MUC5AC+ was not observed in any of the negative for malignancy or reactive cases (0 of 6).

CONCLUSIONS

The most optimal panel for the diagnosis of ductal adenocarcinoma in both the EUS-FNA specimens is a panel including MUC1/MUC2/MUC5AC, whereas a panel of all 4 antibodies (MUC1, 2, 5AC, and 6) will in addition aid in differentiating inadvertently sampled normal/reactive duodenal and gastric epithelium from neoplastic pancreatic tissue.

Different Progression of Tumor Xenografts between Mucin-Producing and Mucin–Non-Producing Mammary Adenocarcinoma-Bearing Mice

Previously, we found that MUC2 mucins could activate monocytes/macrophages through a scavenger receptor leading to cyclooxygenase (COX) 2 induction and overproduction of prostaglandin E2 (PGE2). To investigate the role of mucins in the tumor-bearing state, we compared s.c. tumor formation by using mucin-producing (TA3-Ha) and mucin-non-producing (TA3-St) cloned variants of mouse mammary adenocarcinomas. Expression of COX2 mRNA and protein and production of PGE2 were elevated in peritoneal macrophages stimulated with epiglycanin, which is a mucin-like glycoprotein produced by TA3-Ha cells. S.c. tumor tissues comprising TA3-Ha cells grew much faster than tissues comprising TA3-St cells. COX2 protein and vascular endothelial growth factor in TA3-Ha tumor tissues were elevated compared with the TA3-St tumor tissues. Although similar numbers of macrophages were observed immunochemically in the two types of tumor tissues, COX2 was induced prominently in the infiltrating macrophages in TA3-Ha tumor tissues but only faintly in TA3-St tumor tissues. Furthermore, angiogenesis progressed remarkably in TA3-Ha tumor tissues but only slightly in TA3-St tumor tissues. Epiglycanin-induced overproduction of PGE2 down-regulated interleukin-12 production by macrophages. IFN-gamma-producing CD4 T cells in spleens obtained from TA3-Ha tumor-bearing mice were significantly reduced compared with TA3-St tumor-bearing mice, suggesting that mucins cause PGE2-mediated immune suppression. Actually, the tumor growth of a TA3-Ha cell xenograft was suppressed effectively by oral administration of a COX2 inhibitor but that of a TA3-St cell one was not. These results suggest that mucins play an important role in tumor progression through overproduction of PGE2.

Evaluation of mucin expression patterns in gastric borderline (group III) lesions

BACKGROUND

Recommendations for diagnosis and treatment of gastric borderline (group III) lesions remain controversial. We examined mucin expression patterns in endoscopically resected and forceps biopsy samples.

METHODS

Sixty-three gastric lesions were histopathologically identified as belonging to group III on the basis of an endoscopic forceps biopsy. All of the patients underwent endoscopic resection, and the lesions were classified into group A (final diagnosis, adenocarcinoma) or group B (final diagnosis, adenoma). Immunostaining for MUC2, MUC5AC, MUC6, and CD10 was performed and the mucin phenotype determined. An additional 26 forceps biopsy samples from the above 63 patients were similarly evaluated.

RESULTS

The proportion of complete gastric (positive for MUC5AC and MUC6) plus gastric-predominant phenotypes was significantly higher in group A (58.0%) than in group B (18.7%) lesions (P < 0.05). The proportion of the complete intestinal (positive for MUC2 and CD10) phenotype was significantly higher in group B (68.8%) than in group A (19.4%) (P < 0.05). Similar results were also observed in the 26 forceps biopsy samples histopathologically diagnosed as group III lesions. The proportion of samples with a diffuse Ki-67 immunostaining pattern was significantly higher in group A than in group B (P < 0.05). p53 expression was significantly higher in group A (29.2%) than in group B (4.3%) (P < 0.05).

CONCLUSIONS

Immunostaining of forceps biopsy samples for the mucin phenotype may be helpful for diagnosing gastric borderline (group III) lesions.

Specific amino acids increase mucin synthesis and microbiota in dextran sulfate sodium-treated rats

During the anabolic response associated with inflammation, mucin synthesis and colonic protection may be compromised by the limited availability of specific amino acids. We therefore determined the effect of dietary amino acid supplementation on the microbiota, mucin status, and mucosal damage in dextran sulfate sodium (DSS)-treated rats. From 8 d before to 28 d after colitis induction, male Sprague-Dawley rats (10 mo old, n = 8/group) were fed a control diet supplemented or not with 2 different doses of an amino acid cocktail containing L-threonine, L-serine, L-proline, and L-cysteine. All diets were isonitrogenous (adjusted with L-alanine). The higher dose of amino acids increased the number of Muc2-containing goblet cells in the surface epithelium of the ulcerated area, stimulated mucin production in the colon, and restored the mucin amino acid composition and mucosal content to healthy, control values. The colonic mucin synthesis rate was specifically stimulated by 95%, whereas the protein turnover was unchanged. All bacterial populations, markedly altered by the DSS treatment, were promoted. In conclusion, in inflammatory situations, an increase in threonine, serine, proline, and cysteine dietary supply can promote mucin synthesis, reequilibrate the gut microbiota, and thus favor colonic protection and mucosal healing.

Clinicopathological characteristics, microsatellite instability, and expression of mucin core proteins and p53 in colorectal mucinous adenocarcinomas in relation to location

It has been suggested that right-sided and left-sided colorectal cancer may arise by different mechanisms. However, there have been few studies of mucinous adenocarcinoma (MA) in relation to location. Therefore, we analyzed clinicopathological characteristics, microsatellite instability (MSI), and expression of MUC1, MUC2, MUC5AC mucin core proteins, and p53 by immunohistochemistry in relation to tumor location. Ninety-six consecutive colorectal MAs and ninety-eight nonmucinous adenocarcinomas (nMAs) were investigated. Right-sided MAs, by comparison with those on the left side, were characterized by older age, larger tumor size, lower stage at presentation, peritumoral lymphocytic response, background of serrated adenoma, MSI-H phenotype, higher MUC2 and MUC5AC expression, and lower p53 protein overexpression. Right-sided nMAs, relative to those on the left side, were associated with MSI-H phenotype, higher MUC2 and MUC5AC expression, and lower p53 protein overexpression. Thus, MSI-H phenotype, expression of MUC2 and MUC5AC, and infrequent p53 protein overexpression are associated with right-sided location as well as mucinous histology. In univariate analysis, right-sided location had a favorable effect on disease specific survival of the patients with MA, although it is not an independent predictor of survival. Our results indicate that MA is a distinctive form of colorectal cancer and has different phenotypes depending on tumor location.

Expression profile of mucins (MUC2, MUC5AC and MUC6) in Helicobacter pylori infected pre-neoplastic and neoplastic human gastric epithelium

BACKGROUND

Helicobacter pylori (H. pylori) causes gastritis and intestinal metaplasia (IM) that may evolve to gastric carcinoma. The objective of this study was to compare the profile of mucins in the progressive stages of H. pylori infected pre-neoplastic and neoplastic human gastric epithelium. We used a panel of monoclonal antibodies with well-defined specificities of MUC2, MUC5AC and MUC6 to characterize the expression pattern of mucins by immunohistochemistry.

METHODS

RUT and ELISA were down for H. pylori confirmation. Human gastric biopsy sections were stained using immunohistochemistry with MUC2, MUC5AC and MUC6 antibodies.

RESULTS

MUC5AC was expressed in the superficial epithelium and the upper part of the gastric pits. MUC6 expression was detected in the lower part of the gastric glands. MUC2 was expressed in intestinal metaplasia, mostly in goblet cells. The mucin expression profile in the progressive stages of H. pylori infected human gastric epithelium allows the identification of intestinal metaplasia, which is characterized by a decreased expression of the gastric mucins (MUC5AC and MUC6) and de novo expression of MUC2.

CONCLUSION

In conclusion, our results suggest that there is altered expression of MUC5AC and MUC6 together with the aberrant expression of MUC2 in intestinal metaplasia, during the process of gastric carcinogenesis. The present study indicates that the MUC2 mucin expression pattern is a reliable marker of intestinal metaplasia, which appears in the context of H. pylori infected individuals.

Regulation of mucin expression: mechanistic aspects and implications for cancer and inflammatory diseases

Mucins are large multifunctional glycoproteins whose primary functions are to protect and lubricate the surfaces of epithelial tissues lining ducts and lumens within the human body. Several lines of evidence also support the involvement of mucins in more complex biological processes such as epithelial cell renewal and differentiation, cell signaling, and cell adhesion. Recent studies have uncovered the role of select mucins in the pathogenesis of cancer, underscoring the importance of a detailed knowledge about mucin biology. Under normal physiological conditions, the production of mucins is optimally maintained by a host of elaborate and coordinated regulatory mechanisms, thereby affording a well-defined pattern of tissue-, time-, and developmental state-specific distribution. However, mucin homeostasis may be disrupted by the action of environmental and/or intrinsic factors that affect cellular integrity. This results in an altered cell behavior that often culminates into a variety of pathological conditions. Deregulated mucin production has indeed been associated with numerous types of cancers and inflammatory disorders. It is, therefore, crucial to comprehend the underlying basis of molecular mechanisms controlling mucin production in order to design and implement adequate therapeutic strategies for combating these diseases. Herein, we discuss some physiologically relevant regulatory aspects of mucin production, with a particular emphasis on aberrations that pertain to pathological situations. Our views of the achievements, the conceptual and technical limitations, as well as the future challenges associated with studies of mucin regulation are exposed.

Formation of lactones from sialylated MUC1 glycopeptides

The tumor-associated carbohydrate antigens TN, T, sialyl TN and sialyl T are expressed on mucins in several epithelial cancers. This has stimulated studies directed towards development of glycopeptide-based anticancer vaccines. Formation of intramolecular lactones involving sialic acid residues and suitably positioned hydroxyl groups in neighboring saccharide moieties is known to occur for glycolipids such as gangliosides. It has been suggested that these lactones are more immunogenic and tumor-specific than their native counterparts and that they might find use as cancer vaccines. We have now investigated if lactonization also occurs for the sialyl TN and T antigens of mucins. It was found that the model compound sialyl T benzyl glycoside , and the glycopeptide Ala-Pro-Asp-Thr-Arg-Pro-Ala from the tandem repeat of the mucin MUC1, in which Thr stands for the 2,3-sialyl-T antigen, lactonized during treatment with glacial acetic acid. Compound gave the 1''--> 2' lactone as the major product and the corresponding 1''--> 4' lactone as the minor product. For glycopeptide the 1''--> 4' lactone constitued the major product, whereas the 1''--> 2' lactone was the minor one. When lactonized was dissolved in water the 1''--> 4' lactone underwent slow hydrolysis, whereas the 1''--> 2' remained stable even after a 30 days incubation. In contrast the corresponding 2,6-sialyl-TN glycopeptide did not lactonize in glacial acetic acid.

Prognostic significance of combined expression of MUC1 and adhesion molecules in advanced gastric cancer

The objective of the present study was to evaluate the combination of MUC1 and the status of adhesion molecules in advanced gastric cancers as a possible predictor of patient survival. Two hundred and two paraffin-embedded specimens of gastric carcinoma were examined by immunohistochemical staining using monoclonal antibodies against MUC1 mucin, E-cadherin and beta-catenin. The expression of MUC1 was considered positive if at least 10% of the neoplastic cells were stained. E-cadherin and beta-catenin were classified into four groups. Only a membranous pattern, which was stained as strongly as normal epithelial cells, was judged as normal. The absent pattern (loss of staining), cytoplasmic pattern (cytoplasmic staining with loss of membranous expression), and heterogeneous pattern (cytoplasmic staining with preservation of membranous expression) were considered abnormal. There was a significant relationship between MUC1-positive expression and abnormal expression of E-cadherin (P=0.017). The cancer with abnormal E-cadherin expression or MUC1-positive expression increased, indicating that the cancer invasion was deep. Survival analysis of the outcome revealed that the survival time for those with abnormal E-cadherin/MUC1-positive expression was shorter than for those with other expression patterns. Multivariate analysis revealed that patients with abnormal E-cadherin/MUC1-positive expression had a poorer prognosis with significance (P<0.0001). In conclusion, abnormal E-cadherin/MUC1-positive expression pattern in advanced gastric cancer is an independent unfavorable prognostic marker.