The MUC6 secretory mucin gene is expressed in a wide variety of epithelial tissues

Organization of the human intestine at single-cell resolution

The intestine is a complex organ that promotes digestion, extracts nutrients, participates in immune surveillance, maintains critical symbiotic relationships with microbiota and affects overall health1. The intesting has a length of over nine metres, along which there are differences in structure and function2. The localization of individual cell types, cell type development trajectories and detailed cell transcriptional programs probably drive these differences in function. Here, to better understand these differences, we evaluated the organization of single cells using multiplexed imaging and single-nucleus RNA and open chromatin assays across eight different intestinal sites from nine donors. Through systematic analyses, we find cell compositions that differ substantially across regions of the intestine and demonstrate the complexity of epithelial subtypes, and find that the same cell types are organized into distinct neighbourhoods and communities, highlighting distinct immunological niches that are present in the intestine. We also map gene regulatory differences in these cells that are suggestive of a regulatory differentiation cascade, and associate intestinal disease heritability with specific cell types. These results describe the complexity of the cell composition, regulation and organization for this organ, and serve as an important reference map for understanding human biology and disease.

Primary endometrial gastric (gastro-intestinal)-type carcinoma: A practical approach

The latest WHO classification of the female genital tract tumors introduces a new type of carcinoma: the primary gastric-type (or gastro-intestinal type) carcinoma of the endometrium. This type of neoplasm tends to have a poor outcome, making its correct diagnostic important. As little is known about this entity and given its quite challenging diagnosis, we aim to review existing data about it and propose a practical diagnostic approach. There are currently 11 cases published in 8 articles fitting the precise definition of a primary gastric-type carcinoma of the endometrium. Three main differential diagnoses must be excluded before considering this tumor: endometrioid adenocarcinoma with mucinous (Müllerian-type) differentiation, endocervical primary, and gastro-intestinal primary. Morphological aspects of this tumor can be heterogeneous and confusing; in this context, immunochemistry can be helpful to highlight the gastric or intestinal differentiation, but also to eliminate a mucinous endometrioid adenocarcinoma of Müllerian-type, by the constant negativity of estrogen receptors. A metastasis of a primary gastro-intestinal tract carcinoma must also be excluded by clinical, endoscopic and imaging work-up. Finally, an endometrial extension of a primary endocervical gastric-type carcinoma should be ruled out by complete sampling of the cervix. Intestinal type endocervical adenocarcinoma is easier to eliminate since this is an HPV-associated neoplasm.

Expression of MUC-2, MUC-6, NAPE-PLD, IL-6 and IL-13 in Healthy and Metaplastic Bronchial Epithelium

Background: The normal tissue structure of the respiratory system is necessary to provide adequate protection of the airways and lungs. Prolonged exposure to trigger factors can result in adaptive mechanism activation and lead to the development of chronic pulmonary diseases or even dysplastic changes. Materials and methods: Respiratory system material with a pseudostratified ciliated epithelium was obtained from 12 patients (aged 16 to 95), and material with a stratified squamosa epithelium was obtained from six patients (aged 23 to 93). Routine staining was performed, and an immunohistochemistry was conducted for MUC-2, MUC-6, NAPE-PLD, IL-6 and IL-13. Results: Inflammatory processes were not detected in any of the specimens. A number of correlations were identified, with the most important being a strong positive correlation for IL-13 between the alveolar epithelium and alveolar macrophages and a strong positive correlation for IL-6 between the alveolar epithelium and alveolar macrophages in the stratified squamous epithelium group. We also detected a statistically significant difference in IL-6 in alveolar macrophages. Conclusions: There were no signs of dysplastic changes in either group. Increased secretion of IL-13 in the stratified squamous epithelium group shows its involvement in metaplastic changes in the bronchial epithelium. The secretion of atypical factors by hyaline cartilage demonstrates its plasticity and adaptability.

Regulation of MUC6 Methylation Correlates with Progression of Gastric Cancer

PURPOSE

This study aimed to investigate the mechanistic downregulation of mucin 6 (MUC6) and its influence on the progression of gastric cancer (GC).

MATERIALS AND METHODS

The expression of MUC6 was examined in 40 GC patients. The methylation status of the MUC6 promoter region was investigated using GC cell lines and GC tissue specimens by immunohistochemistry and/or quantitative polymerase chain reaction (qPCR). MUC6 was knocked down in the gastric epithelial cells (GES-1) cell and overexpressed in the SGC7901 cell. The effects of MUC6 knockdown and overexpression on cell migration and invasion were examined using Transwell assays. The effects of demethylation and methylation on MUC6 expression were examined by western blot, qPCR, or double luciferase reporter assays.

RESULTS

The expression of MUC6 in GC with lymph node metastasis and poor pathological stage was significantly lower than that in GC without lymph node metastasis and good pathological stage, respectively. While cell migration and invasion were significantly decreased after overexpression of MUC6, these abilities significantly increased after the knockdown of MUC6. The methylation levels of MUC6 in GC tissues and GC cell lines were significantly higher than those in para-cancerous tissues and normal GES. Promoter methylation could significantly reduce the binding of related transcription factors to the MUC6 promoter. The expression of MUC6 increased with the concentration and time of action of demethylation drugs.

CONCLUSION

Expression of MUC6 was regulated by promotor methylation. This methylation of the MUC6 promoter may lead to significant downregulation of MUC6 in GC and promote the progression of GC.

Clinicopathological and prognostic significance of immunophenotypic characterization of endocervical adenocarcinoma using CLDN18, CDH17, and PAX8 in association with HPV status

In 2020, the WHO published a new system for classifying invasive endocervical adenocarcinoma based on histological features and high-risk human papillomavirus (HPV) infection. However, immunophenotypes of each histological subtype require further investigation. We immunohistochemically analyzed 66 invasive endocervical adenocarcinomas using three cell-lineage-specific markers: claudin 18 (CLDN18) for gastric, cadherin 17 (CDH17) for intestinal, and PAX8 for Müllerian epithelial cells. We identified five immunophenotypes of endocervical adenocarcinoma: gastric (21%); intestinal (14%); gastrointestinal (11%); Müllerian (35%); and not otherwise specified (NOS) (20%). Adenocarcinomas with gastric immunophenotype, characterized by aging (p = 0.0050), infrequent HPV infection (p < 0.0001), concurrent lobular endocervical glandular hyperplasia (p = 0.0060), lymphovascular invasion (p = 0.0073), advanced clinical stage (p = 0.0001), and the poorest progression-free (p < 0.0001) and overall (p = 0.0023) survivals, were morphologically compatible with gastric-type adenocarcinoma of the WHO 2020 classification. Conversely, most adenocarcinomas with Müllerian (91%) and intestinal (89%) immunophenotypes were HPV associated and morphologically compatible with usual- or intestinal-type adenocarcinomas of the WHO 2020 classification. The morphology of adenocarcinomas with gastrointestinal immunophenotype was intermediate or mixed between those of gastric and intestinal immunophenotypes; 57% were HPV associated. Adenocarcinomas with NOS immunophenotype were mainly HPV associated (85%) and histologically poorly differentiated. Multivariate analysis revealed that gastric (p = 0.008), intestinal + gastrointestinal (p = 0.0103), and NOS (p = 0.009) immunophenotypes were independent predictors of progression-free survival. Immunophenotypes characterized by CLDN18, CDH17, and PAX8 exhibited clinicopathological relevance and may improve the diagnostic accuracy and prognostic value of conventional histological classification.

Early Gastric Cancer: identification of molecular markers able to distinguish submucosa-penetrating lesions with different prognosis

BACKGROUND

Early Gastric Cancer (EGC) reaches 25% of the gastric cancers surgically treated in some areas of Northeastern Italy and is usually characterized by a good prognosis. However, among EGCs classified according to Kodama's criteria, Pen A subgroup is characterized by extensive submucosal invasion, lymph node metastases and worse prognosis, whereas Pen B subgroup by better prognosis. The aim of the study was to characterize the differences between Pen A, Pen B and locally advanced gastric cancer (T3N0) in order to identify biomarkers involved in aggressiveness and clinical outcome.

METHODS

We selected 33 Pen A, 34 Pen B and 20 T3N0 tumors and performed immunohistochemistry of mucins, copy number variation analysis of a gene panel, microsatellite instability (MSI), TP53 mutation and loss of heterozygosity (LOH) analyses.

RESULTS

Pen A subgroup was characterized by MUC6 overexpression (p = 0.021). Otherwise, the Pen B subgroup was significantly associated with the amplification of GATA6 gene (p = 0.002). The higher percentage of MSI tumors was observed in T3N0 group (p = 0.002), but no significant differences between EGC types were found. Finally, TP53 gene analysis showed that 32.8% of Pen tumors have a mutation in exons 5-8 and 50.0% presented LOH. Co-occurrence of TP53 mutation and LOH mainly characterized Pen A tumors (p = 0.022).

CONCLUSIONS

Our analyses revealed that clinico-pathological parameters, microsatellite status and frequency of TP53 mutations do not seem to distinguish Pen subgroups. Conversely, the amplification of GATA6 was associated with Pen B, as well as the overexpression of MUC6 and the TP53^mut/LOH significantly characterized Pen A.

Tepotinib Inhibits the Epithelial-Mesenchymal Transition and Tumor Growth of Gastric Cancers by Increasing GSK3β, E-Cadherin, and Mucin 5AC and 6 Levels

Aberrant expression of mucins (MUCs) can promote the epithelial–mesenchymal transition (EMT), which leads to enhanced tumorigenesis. Carcinogenesis-related pathways involving c-MET and β-catenin are associated with MUCs. In this study, we characterized the expression of EMT-relevant proteins including MET, β-catenin, and E-cadherin in human gastric cancer (GC) cell lines, and further characterized the differential susceptibility of these cell lines compared with the c-MET inhibitor tepotinib. We assessed the antitumor activity of tepotinib in GC cell lines. The effects of tepotinib on cell viability, apoptotic cell death, EMT, and c-MET and β-catenin signaling were evaluated by 3-(4,5 dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl)-2H-tetrazolium (MTS), flow cytometry, Western blotting, and qRT-PCR. The antitumor efficacy was assessed in MKN45 xenograft mice. Tepotinib treatment induced apoptosis in c-MET-amplified SNU620, MKN45, and KATO III cells, but had no effect on c-MET-reduced MKN28 or AGS cells. Tepotinib treatment also significantly reduced the protein levels of phosphorylated and total c-MET, phosphorylated and total ERK, β-catenin, and c-MYC in SNU620 and MKN45 cells. In contrast, this drug was only slightly active against KATO III cells. Notably, tepotinib significantly reduced the expression of EMT-promoting genes such as MMP7, COX-2, WNT1, MUC5B, and c-MYC in c-MET-amplified GC cells and increased the expression of EMT-suppressing genes such as MUC5AC, MUC6, GSK3β, and E-cadherin. In a mouse model, tepotinib exhibited good antitumor growth activity along with increased E-cadherin and decreased phosphorylated c-MET (phospho-c-MET) protein levels. Collectively, these results suggest that tepotinib suppresses tumor growth and migration by negatively regulating c-MET-induced EMT. These findings provide new insights into the mechanism by which MUC5AC and MUC6 contribute to GC progression.

Alzheimer Disease Pathology-Associated Polymorphism in a Complex Variable Number of Tandem Repeat Region Within the MUC6 Gene, Near the AP2A2 Gene

We found evidence of late-onset Alzheimer disease (LOAD)-associated genetic polymorphism within an exon of Mucin 6 (MUC6) and immediately downstream from another gene: Adaptor Related Protein Complex 2 Subunit Alpha 2 (AP2A2). PCR analyses on genomic DNA samples confirmed that the size of the MUC6 variable number tandem repeat (VNTR) region was highly polymorphic. In a cohort of autopsied subjects with quantitative digital pathology data (n = 119), the size of the polymorphic region was associated with the severity of pTau pathology in neocortex. In a separate replication cohort of autopsied subjects (n = 173), more pTau pathology was again observed in subjects with longer VNTR regions (p = 0.031). Unlike MUC6, AP2A2 is highly expressed in human brain. AP2A2 expression was lower in a subset analysis of brain samples from persons with longer versus shorter VNTR regions (p = 0.014 normalizing with AP2B1 expression). Double-label immunofluorescence studies showed that AP2A2 protein often colocalized with neurofibrillary tangles in LOAD but was not colocalized with pTau proteinopathy in progressive supranuclear palsy, or with TDP-43 proteinopathy. In summary, polymorphism in a repeat-rich region near AP2A2 was associated with neocortical pTau proteinopathy (because of the unique repeats, prior genome-wide association studies were probably unable to detect this association), and AP2A2 was often colocalized with neurofibrillary tangles in LOAD.

Prognostic Factors for Surgically Resected Intraductal Papillary Neoplasm of the Bile Duct: A Retrospective Cohort Study

BACKGROUND

To date, postoperative prognostic factors for intraductal papillary neoplasm of the bile duct (IPNB) have not been well-established. This study aimed to examine the histopathologic features and postoperative prognosis of the two IPNB subclassifications, as well as factors affecting prognosis, based on the authors' experience at a single institution.

METHODS

The study enrolled 83 patients who underwent surgical resection for pathologically diagnosed IPNB at the authors' institution. The clinicopathologic features and postoperative outcomes for these patients were examined. The study also investigated postoperative prognostic factors for IPNB using uni- and multivariate analyses.

RESULTS

More than half of the tumors (64%) diagnosed as IPNB were early-stage cancer (UICC Tis or T1). However, none were diagnosed as benign. The multivariate analysis showed that lymph node metastasis (hazard ratio [HR], 5.78; p = 0.002) and bile duct margin status with carcinoma in situ (D-CIS; HR, 5.10; p = 0.002) were independent prognostic factors, whereas MUC6 expression showed only a marginal influence on prediction of prognosis (HR, 0.32; p = 0.07). The tumor recurrence rate and the proportion of locoregional recurrence were significantly greater among the patients with D-CIS than among those with negative bile duct margins, including those patients with low-grade dysplasia. The patients with D-CIS showed a significantly poorer prognosis than those with negative bile duct margins (5-year survival, 38% versus 87%; p = 0.0002).

CONCLUSIONS

Evaluation of resected IPNBs showed cancer in all cases. Avoiding positive biliary stumps during surgery, including resection of carcinoma in situ, would improve the prognosis for patients with IPNB.

Evidence from ileum and liver transcriptomes of resistance to high-salt and water-deprivation conditions in camel

Camels have evolved various resistance characteristics adaptive to their desert habitats. In the present study, we used high-throughput sequencing to investigate stress-induced alternative splicing events as well as different genes involved in resistance to water deprivation and salt absorption in the ileum and liver in Camelus bactrianus. Through association analyses of mRNA, miRNA and lncRNA, we sought to explicate how camels respond to high salt and water scarcity conditions. There were two modes by which genes driven by alternative splicing were enriched to molecular functions, invoking of which was potentially fixed by organ and stress types. With qRT-PCR detection, the differentially expressed MUC6, AQP5, LOC105076960, PKP4, CDH11, TENM1, SDS, LOC105061856, PLIN2 and UPP2 were screened as functionally important genes, along with miR-29b, miR-484, miR-362-5p, miR-96, miR-195, miR-128 and miR-148a. These genes contributed to cellular stress resistance, for instance by reducing water loss, inhibiting excessive import of sodium, improving protective barriers and sodium ion homeostasis, and maintaining uridine content. The underlying competing endogenous RNAs referred to LNC001664, let-7e and LOC105076960 mRNA in ileum, and LNC001438, LNC003417, LNC001770, miR-199c and TENM1 mRNA in liver. Besides competent interpretation to resistance, there may be inspirations for curing human diseases triggered by high-salt intake.

The MUC6/AP2A2 Locus and Its Relevance to Alzheimer's Disease: A Review

We recently reported evidence of Alzheimer's disease (AD)-linked genetic variation within the mucin 6 (MUC6) gene on chromosome 11p, nearby the adaptor-related protein complex 2 subunit alpha 2 (AP2A2) gene. This locus has interesting features related to human genomics and clinical research. MUC6 gene variants have been reported to potentially influence viral-including herpesvirus-immunity and the gut microbiome. Within the MUC6 gene is a unique variable number of tandem repeat (VNTR) region. We discovered an association between MUC6 VNTR repeat expansion and AD pathologic severity, particularly tau proteinopathy. Here, we review the relevant literature. The AD-linked VNTR polymorphism may also influence AP2A2 gene expression. AP2A2 encodes a polypeptide component of the adaptor protein complex, AP-2, which is involved in clathrin-coated vesicle function and was previously implicated in AD pathogenesis. To provide background information, we describe some key knowledge gaps in AD genetics research. The "missing/hidden heritability problem" of AD is highlighted. Extensive portions of the human genome, including the MUC6 VNTR, have not been thoroughly evaluated due to limitations of existing high-throughput sequencing technology. We present and discuss additional data, along with cautionary considerations, relevant to the hypothesis that MUC6 repeat expansion influences AD pathogenesis.

High-fat Diet Alters the Glycosylation Patterns of Duodenal Mucins in a Murine Model

High-fat diet (HFD) alters the glycosylation patterns of intestinal mucins leading to several health problems. We studied by histochemical and lectin-binding methods mucin alterations in the duodenum of mice fed a HFD for 25 weeks. Histochemical methods included periodic acid-Schiff, alcian blue pH 2.5, and high-iron diamine. Lectin-binding experiments were performed with SBA, PNA, WGA, MAA-II, SNA, ConA, UEA-I, LTA, and AAA. SBA, PNA, WGA, MAA-II, and SNA were tested also after desulfation and ConA after periodate-sodium borohydrate treatments (paradoxical ConA). Duodenal mucins are secreted by Brunner's glands and goblet cells in the villi. Brunner's glands of HFD mice showed increased secreting activity and a general reduction of glycosylated residuals, such as fucose and terminal α1,4-linked GlcNAc. Moreover, a general reduction of glycosylated residuals in the goblet cells of villi such as the fucosylated and sulfated ones was observed. Since the cited residuals are involved in cytoprotective and cytostatic functions, as well as in interactions with the intestinal microbiota and protection against parasites and inflammatory disorders, we conclude that HFD can predispose duodenum to several possible health disorders.

EGF-Containing Membrane-Bound Mucins: A Hidden ErbB2 Targeting Pathway?

Membrane-bound mucins belong to a heterogeneous family of large O-glycoproteins involved in numerous cancers and inflammatory diseases of the epithelium. Some of them are also involved in protein-protein interactions, with receptor tyrosine kinase ErbB2, and fundamental and clinical data showed that these complexes have a detrimental impact on cancer outcome, thus raising interest in therapeutic targeting. This paper aims to demonstrate that MUC3, MUC4, MUC12, MUC13, and MUC17 have a common evolutionary origin and share a common structural organization with EGF-like and SEA domains. Theoretical structure-function relationship analysis of the conserved domains indicated that the studied membrane-bound mucins share common biological properties along with potential specific functions. Finally, the potential druggability of these complexes is discussed, revealing ErbB2-related pathways of cell signaling to be targeted.

Engineering drug delivery systems to overcome mucosal barriers for immunotherapy and vaccination

Mucosal surfaces protect our bodies from pathogens and external irritants using a system of biological barriers. Overcoming these barriers is a significant drug delivery challenge, particularly for immunotherapies that aim to modulate the local immune response. Reaching local lymphoid tissues and draining lymph nodes (LNs) requires crossing the mucus mesh, mucosal epithelium, and either targeting M cells covering lymphoid tissues or utilizing lymphatic transport that shuttles molecules and particulates from the periphery to the LN. We first highlight the barrier properties of mucus and mucosal epithelium, and the function of the mucosal immune system. We then dive into existing drug delivery technologies that have been engineered to overcome each of these barriers. We particularly focus on novel strategies for targeting lymphoid tissues, which has been shown to enhance immunotherapies and vaccinations, via directly targeting LNs, lymphatic vessels, and M cells that transport samples of mucosal content to the lymphoid tissues.

Primary Vaginal Gastric-type Adenocarcinoma and Vaginal Adenosis Exhibiting Gastric Differentiation: Report of a Series With Detailed Immunohistochemical Analysis

So-called gastric-type adenocarcinoma and related premalignant lesions have been characterized in the cervix, but similar lesions are not widely recognized in the vagina. We report a series of 11 vaginal glandular lesions exhibiting gastric differentiation, comprising 5 cases of adenocarcinoma and 6 of adenosis. All cases occurred in adults (aged 33 to 69) with no known history of diethylstilboestrol exposure. The vaginal adenocarcinomas exhibited morphologic features identical to gastric-type adenocarcinoma of the cervix, but 1 case additionally demonstrated basaloid and sarcomatoid components, which have not been previously reported in cervical gastric-type adenocarcinoma. Immunohistochemically, the adenocarcinomas were positive for MUC6 (4/5), PAX8 (3/5), CK7 (5/5), CK20 (1/5), CDX2 (5/5), CA19.9 (5/5), CEA (4/5), CA125 (5/5), and hepatocyte nuclear factor 1β (5/5). p16, estrogen receptor, and Napsin A were negative in all cases tested, whereas p53 exhibited mutation-type staining in 3/5 cases. In all 5 adenocarcinomas, a component of adenosis with benign or atypical nuclear features was identified; the adenosis displayed gastric morphology in 4 cases and tuboendometrial morphology in 1. The 6 cases of pure vaginal adenosis (without associated adenocarcinoma) all contained gastric-type mucinous glands together with tuboendometrial glands in 2 cases. There was focal intestinal differentiation with goblet cells in all 6 cases and neuroendocrine cells with eosinophilic granules in 3. Cytologic atypia was observed in 4/6 cases of pure vaginal adenosis. Immunohistochemically, the gastric-type adenosis (10 cases) was positive for MUC6 (10/10), estrogen receptor (5/10), PAX8 (8/10), CK7 (9/9), CK20 (2/9), CDX2 (5/9), CA19.9 (8/9), CEA (6/9), CA125 (6/9), hepatocyte nuclear factor 1β (10/10), and Napsin A (1/10). p53 exhibited wild-type immunoreactivity in all 10 cases, whereas p16 was negative in all cases tested. Scattered individual chromogranin-positive cells were present in all 5 cases of pure adenosis tested. Follow-up was available in 4 of the adenocarcinoma cases, with 3 patients dead of disease within 1 to 3 years and 1 patient alive with disease at 1 year. The morphologic and immunohistochemical findings in our study suggest a close relationship between vaginal gastric-type adenocarcinoma and adenosis exhibiting gastric differentiation. This probably represents a distinct pathway of vaginal gastric-type carcinogenesis analogous to that occurring in the cervix. We propose that gastric-type adenocarcinoma be recognized as a distinct histologic subtype of vaginal adenocarcinoma while vaginal adenosis of gastric-type represents a novel subtype of adenosis that requires further study to clarify its biological potential.

Immunophenotypic Comparison of Neoplasms of the Appendix, Right Colon, and Left Colon in Search of a Site-Specific Phenotypic Signature

Aims. The proximal colon derives from the midgut endoderm, the distal one third derives from the hindgut endoderm, and the distal anal canal is of ectodermal origin. At least 5 molecular subtypes of colorectal carcinomas (CRC) have been identified, and some have a marked preferential right-sided location. Histologically, some CRC are much more common in the appendix. We hypothesized that these findings suggest the existence of diverse molecular genetic colonic subregions and compared the expression of classic and recently discovered colorectal markers in tumors at various locations to determine if a site-specific immunophenotypic signature could be identified. Methods and Results. Immunostains for CK7, CK20, MUC2, MUC5AC, MUC6, SATB2, DCR3/TNF6B, CDX2, Ki-67, and MMR proteins were performed on 17 appendiceal low-grade mucinous neoplasms and 6 crypt cell adenocarcinomas of the appendix, 15 right-sided and 15 left-sided mucinous adenocarcinomas, 17 right-sided and 15 left-sided conventional adenocarcinomas, and 5 signet ring cell adenocarcinomas (SRCCA). Statistically significant differences in the expression of MUC2, MUC5AC, MUC6, CK7, and SATB2 by site and/or histologic type were documented. MMR deficiency showed a significant correlation with MUC5AC and MUC6 expression. DCR3, CDX2, and CK20 expression was consistent throughout the colon. A CK7+/CK20+ phenotype was most common in appendiceal tumors and SRCCA. Conclusions. Statistically significant differences in the expression of some markers by histologic type and site were documented, supporting the existence of regional molecular genetic heterogeneity in the colon that result in site-specific epigenetic susceptibilities, tumor phenotypes, and immunophenotypes.

Subtyping of IPMN

Intraductal papillary mucinous neoplasms (IPMNs) characteristically consist of mucin-filled dilated ducts lined with neoplastic cells forming papillae with a diverse range of morphologies and varying grades of atypia. Based on morphological characteristics and immunohistochemical reaction against mucin proteins, IPMNs are classified into four distinct subtypes: gastric, intestinal, pancreatobiliary, and oncocytic. In this chapter, histomorphological criteria and techniques of immunohistochemical staining and its evaluation for subtyping IPMNs are described.

Modeling Spatial Correlation of Transcripts with Application to Developing Pancreas

Recently high-throughput image-based transcriptomic methods were developed and enabled researchers to spatially resolve gene expression variation at the molecular level for the first time. In this work, we develop a general analysis tool to quantitatively study the spatial correlations of gene expression in fixed tissue sections. As an illustration, we analyze the spatial distribution of single mRNA molecules measured by in situ sequencing on human fetal pancreas at three developmental time points–80, 87 and 117 days post-fertilization. We develop a density profile-based method to capture the spatial relationship between gene expression and other morphological features of the tissue sample such as position of nuclei and endocrine cells of the pancreas. In addition, we build a statistical model to characterize correlations in the spatial distribution of the expression level among different genes. This model enables us to infer the inhibitory and clustering effects throughout different time points. Our analysis framework is applicable to a wide variety of spatially-resolved transcriptomic data to derive biological insights.

Trefoil factor family 2 protein: a potential immunohistochemical marker for aiding diagnosis of lobular endocervical glandular hyperplasia and gastric-type adenocarcinoma of the uterine cervix

Gastric-type adenocarcinoma (GA) is an aggressive subtype of cancer of the uterine cervix. Several immunohistochemical markers for gastric mucins, such as mucin 6 (MUC6) and N-acetylglucosamine α1 → 4galactose → R (αGlcNAc-R), which is recognized by HIK1083 antibody, have been introduced for diagnosis of GA and lobular endocervical glandular hyperplasia (LEGH). However, MUC6 is also expressed in normal endocervical glands and HIK1083 antibody has limited availability. Trefoil factor family 2 protein (TFF2) is secreted by gastric, but not normal endocervical glands. Here, we evaluated TFF2 immunostaining for detection of a gastric immunophenotype in endocervical glandular lesions. We compared TFF2, αGlcNAc-R, and MUC6 expression in 103 endocervical glandular lesions: LEGH (n = 23), adenocarcinoma in situ/microinvasive adenocarcinoma (AIS-MIA) (n = 29), and invasive adenocarcinoma (usual type [UA], n = 26; GA, n = 11; intestinal type [IA], n = 2; signet ring cell type [Sig], n = 2; and mucinous adenocarcinoma not otherwise specified [NOS], n = 10). TFF2 and αGlcNAc-R expression was completely concordant in each subtype: LEGH (100%), AIS-MIA (44.8%), UA (26.9%), GA (90.9%), IA (100%), Sig (0%), and NOS (20%). TFF2 staining scores were significantly correlated with those of αGlcNAc-R in these lesions. TFF2 and αGlcNAc-R immunoreactivity was present in cytoplasmic mucins and luminal secretions. TFF2 and αGlcNAc-R were not expressed in the normal endocervical glands. MUC6 was frequently expressed in normal endocervical glands and endocervical glandular lesions. Endocervical adenocarcinomas sometimes stained only for MUC6. TFF2 is a promising immunohistochemical marker and its identification in uterine cervical secretion is a potentially useful diagnostic test for endocervical glandular lesions with gastric differentiation.

Expression of Gastric Markers Is Associated with Malignant Potential of Nonampullary Duodenal Adenocarcinoma

BACKGROUND

Sporadic nonampullary duodenal epithelial tumors (NADETs) are uncommon, and thus their clinicopathological features have not been fully assessed.

AIMS

In this study, we have analyzed a series of early sporadic NADETs, focusing on various immunohistological features.

METHODS

We conducted a multicenter retrospective analysis of 68 patients with endoscopically resected sporadic NADETs. Associations between immunohistological features and clinicopathological features were statistically analyzed.

RESULTS

The 68 patients consisted of 46 men (68%) and 22 women (32%) with a mean age of 60.7 ± 12.2 years (range 37-85 years). The 68 tumors were composed of 39 adenomas (57%) and 29 early-stage adenocarcinomas (43%). Duodenal adenocarcinomas were larger in size than adenomas and had papillary architecture in their pathological diagnosis with statistical significance. Duodenal adenocarcinomas also demonstrated a significantly higher expression of gastric markers (MUC5AC and MUC6) and a higher MIB-1 index. Duodenal adenomas were contrastively apt to express intestinal markers (MUC2, CDX1 and CDX2). Of the 68 cases analyzed, there were only 3 tumors positive for p53 staining, all of which were adenocarcinoma. When 7 submucosal invasive cancers and 21 intramucosal cancers were compared, submucosal invasion was positively associated with expression of MUC5AC. Also, submucosal invasion showed strong association with double-positivity of MUC5AC and MUC6.

CONCLUSIONS

Our results indicate that immunohistochemical evaluation is useful for predicting malignant potential of NADETs, especially focusing on the expression of gastrointestinal markers.

Identification of a low frequency missense mutation in MUC6 contributing to pulmonary artery hypertension by whole-exome sequencing

Pulmonary arterial hypertension (PAH) represents a progressive disease characterized by abnormally high blood pressure in the pulmonary artery. Although mutations in the bone morphogenetic receptor 2 (BMPR2) are found in 80% of heritable, their low penetrance suggests that other unidentified genetic modifiers are required for this disease. In this report, whole-exome sequencing (WES) and a linkage analysis were performed on genomic DNA isolated from four affected relatives and one non-affected relative in two PAH families. By focusing on meaningful variants which were presented in the four affected family members, but not presented in the non-affected individual, 49 SNP and eight indel variants in 39 genes were identified as candidates. Further high-throughput multiplex genotyping and Sanger sequencing were carried out to confirm the putative causal mutations in 150 individuals (30 idiopathic PAH [IPAH] patients, 30 chronic thromboembolic pulmonary hypertension [CTEPH] patients, and 90 normal controls). A heterozygous and deleterious mutation in the gene MUC6 (p.Pro1716Ser) was confirmed in the IPAH group (20/30, 67%) and CTEPH group (1/30, 3.33%); no variant was detected in the 90 normal controls. MUC6, which is short for mucin 6, encodes high molecular weight glycoprotein produced by many epithelial tissues and forms an insoluble mucous barrier that protects the lumens. We re-confirmed this low frequency mutation with the 1000 Genomes database across all species; no population or frequency data of this allele were acquired. We also found that this mutation site was highly conserved in different species and predicted MUC6 has the protection function of the airway and pneumoangiogram based on genomic sequence data. The compound heterozygous MUC6 gene mutation (p.Pro1716Ser) suggests a novel disease mechanism leading to PAH.

Ductal Mucus Obstruction and Reduced Fluid Secretion Are Early Defects in Chronic Pancreatitis

Objective: Defective mucus production in the pancreas may be an important factor in the initiation and progression of chronic pancreatitis (CP), therefore we aimed to (i) investigate the qualitative and quantitative changes of mucus both in human CP and in an experimental pancreatitis model and (ii) to correlate the mucus phenotype with epithelial ion transport function.

Design: Utilizing human tissue samples and a murine model of cerulein induced CP we measured pancreatic ductal mucus content by morphometric analysis and the relative expression of different mucins in health and disease. Pancreatic fluid secretion in CP model was measured in vivo by magnetic resonance cholangiopancreatography (MRCP) and in vitro on cultured pancreatic ducts. Time-changes of ductal secretory function were correlated to those of the mucin production.

Results: We demonstrate increased mucus content in the small pancreatic ducts in CP. Secretory mucins MUC6 and MUC5B were upregulated in human, Muc6 in mouse CP. In vivo and in vitro fluid secretion was decreased in cerulein-induced CP. Analysis of time-course changes showed that impaired ductal ion transport is paralleled by increased Muc6 expression.

Conclusion: Mucus accumulation in the small ducts is a combined effect of mucus hypersecretion and epithelial fluid secretion defect, which may lead to ductal obstruction. These results suggest that imbalance of mucus homeostasis may have an important role in the early-phase development of CP, which may have novel diagnostic and therapeutic implications.

A Sensitive and Rapid Method to Determin the Adhesion Capacity of Probiotics and Pathogenic Microorganisms to Human Gastrointestinal Mucins

Mucus is the habitat for the microorganisms, bacteria and yeast that form the commensal flora. Mucins, the main macromolecules of mucus, and more specifically, the glycans that cover them, play essential roles in microbial gastrointestinal colonization. Probiotics and pathogens must also colonize mucus to have lasting positive or deleterious effects. The question of which mucin-harboured glycan motifs favour the adhesion of specific microorganisms remains very poorly studied. In the current study, a simple test based on the detection of fluorescent-labeled microorganisms raised against microgram amounts of mucins spotted on nitrocellulose was developed. The adhesion of various probiotic, commensal and pathogenic microorganisms was evaluated on a panel of human purified gastrointestinal mucins and compared with that of commercially available pig gastric mucins (PGM) and of mucins secreted by the colonic cancer cell line HT29-MTX. The latter two proved to be very poor indicators of adhesion capacity on intestinal mucins. Our results show that the nature of the sialylated cores of O-glycans, determined by MALDI MS-MS analysis, potentially enables sialic acid residues to modulate the adhesion of microorganisms either positively or negatively. Other identified factors affecting the adhesion propensity were O-glycan core types and the presence of blood group motifs. This test should help to select probiotics with enhanced adhesion capabilities as well as deciphering the role of specific mucin glycotopes on microbial adhesion.

Probiotic supplementation affects the glycan composition of mucins secreted by Brunner's glands of the pig duodenum

The effect of a dietary probiotic blend on the carbohydrate composition of mucins secreted by the Brunner's glands in the duodenum of growing-finishing pigs was investigated by means of conventional (periodic acid-Schiff, Alcian Blue pH 2.5, high iron diamine staining) and lectin (15 lectins) histochemistry. Pigs were assigned to two dietary treatments: a control basal diet without the probiotic blend (No-Pro) and a test diet that included the probiotic blend (Pro). Duodenal tissue fragments were fixed in 4% phosphate-buffered-saline-buffered paraformaldehyde, dehydrated through a graded alcohol series, and embedded in paraffin wax. The secretory cells of the Brunner's glands from No-Pro pigs primarily produced neutral glycoproteins and a small amount of acidic non-sulphated mucins. This glycan pattern was opposite that of the Brunner's glands from Pro animals. A comparison of lectin-binding profiles of the secretory cells of Brunner's glands in these two groups showed that in Pro pigs, there was (i) a decrease in N-linked glycans containing α1,2-linked fucose (Con A, UEA I); (ii) a loss of complex types of N-glycans (PHA-L, PHA-E) terminating with lactosamine (RCA₁₂₀), α1,6- and α1,3-linked fucose (LTA), and α-galactose (GSA I-B₄), as well as of O-glycans with terminal Galβ1,3GalNAc (PNA); and (iii) an increase in O-glycans containing GalNAc HPA. No-Pro and Pro samples showed no change in the expression of α2,6 sialoglycans and terminal GlcNAc residues and no affinity for MAL II, DBA, and SBA. These results indicate that probiotic supplementation affects the glycan composition of mucins produced in the Brunner's glands of growing-finishing pigs. These changes could effectively act on the gastrointestinal function and health status of these animals because the probiotic blend induced higher growth performance and meat quality in the test probiotic group than it did in the control basal diet group (Tufarelli et al., 2017).

Uncommon hereditary gynaecological tumour syndromes: pathological features in tumours that may predict risk for a germline mutation

The most common hereditary gynaecological tumour syndromes are hereditary breast and ovarian cancer syndrome and Lynch syndrome. However, pathologists also may encounter gynaecological tumours in women with rare hereditary syndromes. Many of these tumours exhibit distinctive gross and microscopic features that are associated with a risk for an inherited gene mutation. The sensitivity and specificity of these tumour pathology features for predicting an inherited mutation vary depending on the syndrome. By recognising these tumour features, pathologists may potentially contribute to the diagnosis of an unsuspected syndrome by recommending referral of the patient for formal risk assessment by genetic counselling. Patients additionally benefit from diagnosis of an inherited syndrome because many also carry a lifetime risk for developing primary malignancies outside of the gynaecological tract. Early diagnosis of an inherited syndrome permits early screening, detection, and management of additional malignancies associated with the syndrome. This review highlights these rare syndromes and their tumour pathology, including Peutz-Jeghers syndrome (gastric type mucinous carcinoma of the cervix; ovarian sex cord tumour with annular tubules); hereditary leiomyoma renal cell carcinoma syndrome (uterine leiomyoma); tuberous sclerosis complex (uterine PEComa; uterine lymphangioleiomyomatosis); DICER1 syndrome (ovarian Sertoli-Leydig cell tumour; cervical embryonal rhabdomyosarcoma); rhabdoid tumour predisposition syndrome 2 (small cell carcinoma of the ovary, hypercalcaemic type); Cowden syndrome (endometrial endometrioid adenocarcinoma); naevoid basal cell carcinoma syndrome (ovarian fibroma); and Von Hippel-Lindau syndrome (clear cell papillary cystadenoma of the broad ligament).

Physicochemical properties of mucus and their impact on transmucosal drug delivery

Mucus is a selective barrier to particles and molecules, preventing penetration to the epithelial surface of mucosal tissues. Significant advances in transmucosal drug delivery have recently been made and have emphasized that an understanding of the basic structure, viscoelastic properties, and interactions of mucus is of great value in the design of efficient drug delivery systems. Mucins, the primary non-aqueous component of mucus, are polymers carrying a complex and heterogeneous structure with domains that undergo a variety of molecular interactions, such as hydrophilic/hydrophobic, hydrogen bonds and electrostatic interactions. These properties are directly relevant to the numerous mucin-associated diseases, as well as delivering drugs across the mucus barrier. Therefore, in this review we discuss regional differences in mucus composition, mucus physicochemical properties, such as pore size, viscoelasticity, pH, and ionic strength. These factors are also discussed with respect to changes in mucus properties as a function of disease state. Collectively, the review seeks to provide a state of the art roadmap for researchers who must contend with this critical barrier to drug delivery.

Foamy gland changes in gastric-type endocervical neoplasia

Foamy gland (FG) change is a distinctive morphological alteration most widely recognised in adenocarcinomas of the prostate and pancreas, and characterised by cells showing prominent cytoplasmic microvacuolation often with deceptively bland nuclear appearances. To our knowledge, FG alteration has not been described in endocervical neoplasia. We report four patients with gastric-type endocervical neoplasms (3 invasive and 1 in situ) in which FG change was present in 30-80% of the tumour cells. The mean age was 56.5 years (range 45-66 years) and three patients, one of whom also had post-coital bleeding, had atypical glandular cells detected on cervical cytology. Three cases showed a pure gastric phenotype and benign gastric-type changes including pyloric metaplasia, tunnel clusters and/or lobular endocervical glandular hyperplasia were also present. These cases were MUC6 positive and p16 negative on immunohistochemistry while HPV was not detected. One adenocarcinoma showed a mixed histological pattern including usual-type endocervical carcinoma and gastric-type adenocarcinoma: only the latter component expressed MUC6 and this case was p16 and HPV18 positive. This report expands the morphological spectrum exhibited by gastric-type endocervical lesions and the range of anatomical sites in which neoplasms with FG features may be encountered.

Expression Of Mucin Gene Products in Laryngeal Squamous Cancer

OBJECTIVE: Mucins are high-molecular-weight glycoproteins present at the outer surface of mammalian cells. The objective of this study was to examine the expression of mucin (MUC) genes 3, 4, 5AC, 5B, 6, and 7 in early and late laryngeal squamous cancer using the in situ hybridization technique.

STUDY DESIGN: Retrospective analysis of pathological archive specimens.

RESULTS: While MUC 3 and 7 are expressed in a small proportion of early cancers, MUC 5AC, 5B, and 6 are not expressed in laryngeal squamous cancer. MUC 4 was expressed in 13 of the 30 patients. Ten patients and 3 patients with stage 1 and stage 4 disease respectively expressed MUC 4 gene (Fisher's exact, P = 0.02). MUC 4-positive patients had a definite trend towards better survival (log rank test, P = 0.05). In the presence of tumor stage and comorbidity grade, Cox's proportional hazards model failed to statistically confirm the survival advantage provided by MUC 4 gene expression.

CONCLUSION: There is a survival advantage for patients with advanced-stage nonmetastatic cancer when the MUC 4 gene is expressed.AIMS: To study the expression of mucin (MUC) genes 3, 4, 5AC, 5B, 6, and 7 in early and advanced squamous cell cancer of the larynx; to attempt to correlate changes in gene expression with tumor stage by studying stage I and stage IV (AJCC, 1988) tumors.

Molecular determinants for lymph node metastasis in clinically early-stage endometrial cancer

Patients with occult lymph node metastasis in endometrioid-type endometrial cancer (EC) are prone to the development of recurrences and have worse outcomes compared with patients without lymph node metastasis. In the current study, the aim was to identify molecular parameters associated with lymph node metastasis in EC clinically early-stage disease. A univariate analysis of differentially expressed genes, proteins and clinicopathological parameters (including myometrial invasion and tumor grade) was performed, comparing EC patients with and without lymph node metastasis (n=262 patients from The Cancer Genome Atlas). Significant parameters were introduced in a multivariate model and a gene expression pathway analysis. Lymph node metastasis was associated with expression of 268 unique genes (P<0.001), 19 unique proteins (P<0.05), tumor grade and myometrial invasion in univariate analysis. Multivariate analysis demonstrated 10 genes independently associated with lymph node metastasis and 4 independently associated proteins. Myometrial invasion was the only independent clinicopathological parameter associated with lymph node status. The enrichment pathway analysis demonstrated that expression of epidermal growth factor receptor, Bcl2 antagonist of cell death and phosphatase and tensin homolog pathways were significantly involved in lymph node metastasis (P≤0.001). A gene expression signature to predict lymph node status in EC was created for future validation. Few studies have focused on the association between EC's molecular characteristics and nodal metastasis. Defining molecular risk factors for EC lymphatic nodal metastasis may help to individualize treatment and improve patient outcomes.

Comparative glycopattern analysis of mucins in the Brunner's glands of the guinea-pig and the house mouse (Rodentia)

The mucins secreted by the Brunner's glands and the duodenal goblet cells of the Guinea-pig and the house mouse were compared by conventional and FITC-conjugated lectin histochemistry. Methylation/saponification and sialidase digestion were performed prior to lectin binding to detect the residues subterminal to sulfated groups and sialic acid, respectively. In the Guinea-pig the Brunner's glands produce class-III stable sulfosialomucins. Sialic acid is mostly 2,6-linked to galactose or to N-acetylgalactosamine and is in part O-acetylated in C7, C8, and C9. Sulfated groups are probably linked to sialic acid and N-acetylgalactosamine. Terminal residuals of N-acetylglucosamine, galactose, N-acetylgalactosamine and fucose linked in α1,2, α1,3, and α1,4 are also present. Duodenal goblet cells of the Guinea-pig present a lower number of residuals in respect to the Brunner's glandular ones, with sialic acid and N-acetylgalactosamine subterminal to sulfated groups. In the house mouse the Brunner's glands produce class-III stable neutral mucins, binding to same lectins as in the Guinea-pig except for those specific to sialic acid. A diversity of fucosylated residuals higher than in the Guinea-pig is observed. The mouse duodenal goblet cells lack stable class-III mucins, have little sialic acid and present a lower number of residuals in respect to the correspondent Brunner's glands. Regulation of the acidic intestinal microenvironment, prevention of pathologies and hosting of microflora can explain the observed results and the differences observed between the two rodents.

Exploring the role and diversity of mucins in health and disease with special insight into non-communicable diseases

Mucins are major glycoprotein components of the mucus that coats the surfaces of cells lining the respiratory, digestive, gastrointestinal and urogenital tracts. They function to protect epithelial cells from infection, dehydration and physical or chemical injury, as well as to aid the passage of materials through a tract i.e., lubrication. They are also implicated in the pathogenesis of benign and malignant diseases of secretory epithelial cells. In Human there are two types of mucins, membrane-bound and secreted that are originated from mucous producing goblet cells localized in the epithelial cell layer or in mucous producing glands and encoded by MUC gene. Mucins belong to a heterogeneous family of high molecular weight proteins composed of a long peptidic chain with a large number of tandem repeats that form the so-called mucin domain. The molecular weight is generally high, ranging between 0.2 and 10 million Dalton and all mucins contain one or more domains which are highly glycosylated. The size and number of repeats vary between mucins and the genetic polymorphism represents number of repeats (VNTR polymorphisms), which means the size of individual mucins can differ substantially between individuals which can be used as markers. In human it is only MUC1 and MUC7 that have mucin domains with less than 40% serine and threonine which in turn could reduce number of PTS domains. Mucins can be considered as powerful two-edged sword, as its normal function protects from unwanted substances and organisms at an arm's length while, malfunction of mucus may be an important factor in human diseases. In this review we have unearthed the current status of different mucin proteins in understanding its role and function in various non-communicable diseases in human with special reference to its organ specific locations. The findings described in this review may be of direct relevance to the major research area in biomedicine with reference to mucin and mucin associated diseases.

Aberrant expression of annexin A10 is closely related to gastric phenotype in serrated pathway to colorectal carcinoma

Annexin A10 (ANXA10) is a member of the ANX family that is normally expressed in gastric mucosa. ANXA10 was recently observed to be upregulated in sessile serrated adenoma, a precursor to microsatellite-unstable colorectal cancer. We investigated the use of ANXA10 in diagnosing colorectal carcinoma. In an immunohistochemical analysis, the intensity and quantity of ANXA10, MUC5AC, MUC6 and CDX2 in 123 colorectal carcinomas were graded. We determined the molecular status of BRAF and KRAS mutations, as well as the microsatellite instability status and the CpG island methylator phenotype in all colorectal carcinomas, and subcategorized into four molecular subgroups according to the molecular derangements. Nuclear ANXA10 staining was present in 36 colorectal carcinomas, exhibiting a strong significant association with the BRAF mutation status (P<0.0001) and positive CpG island methylator phenotype (P<0.0001), and a borderline significant association with high levels of microsatellite instability (P=0.072). The ANXA10-positive colorectal carcinomas were frequently positive for MUC5AC and MUC6, and were associated with absent or reduced CDX2 expression (all P<0.0001). According to a classification and regression tree analysis, ANXA10 is a superior marker for the molecular subtyping of colorectal carcinomas and represents a specific marker for colorectal cancers of the serrated pathway. Our results indicated that ANXA10 expression is implicated in gastric programming in serrated-pathway-associated colorectal carcinoma. ANXA10-positive colorectal carcinoma is highly associated with the molecular features of the serrated neoplasia pathway.

Squamoid cyst of pancreatic ducts: a case series describing novel immunohistochemistry, cytology, and quantitative cyst fluid chemistry

Squamoid cyst of pancreatic ducts (SCPD) is a benign pancreatic cyst often misdiagnosed preoperatively as a mucinous cyst. The histopathologic features are well described but the cytology and quantitative fluid chemistry profiles from fine-needle aspiration have not been reported. This case series discusses the cytology and cyst fluid chemistry profiles in 2 SCPDs and describes morphologic and immunohistochemical features that have not been previously reported. Fine-needle aspiration of 2 SCPDs yielded acellular debris lacking mucin or exfoliated squamous cells. Two cysts had elevated fluid carcinoembryonic antigen (CEA) and amylase levels. Positive immunohistochemical staining included cytokeratin 5/6, pCEA, synaptophysin, and chromogranin (both focal). MUC2 and MUC5AC showed negativity in all cases, while PAX8 showed negative nuclear staining. An accurate preoperative diagnosis of SCPD is potentially difficult in the setting of elevated fluid CEA levels, and acellular cytology as a mucinous cyst cannot be confidently excluded.

Proteomic mucin profiling for the identification of cystic precursors of pancreatic cancer

BACKGROUND

Pancreatic cystic lesions (PCLs) are increasingly frequent radiological incidentalomas, with a considerable proportion representing precursors of pancreatic cancer. Better diagnostic tools are required for patients to benefit from this development.

METHODS

To evaluate whether cyst fluid mucin expression could predict malignant potential and/or transformation in PCLs, a proteomic method was devised and prospectively evaluated in consecutive patients referred to our tertiary center for endoscopic ultrasound-guided aspiration of cystic lesions from May 2007 through November 2008 (discovery cohort) and from December 2008 through October 2012 (validation cohort). Cytology and cyst fluid carcinoembryonic antigen (CEA; premalignancy > 192 ng/mL, malignancy > 1000 ng/mL) were routinely analyzed, and samples were further processed as follows: one-dimensional gel electrophoresis, excision of high-mass areas, tryptic digestion and nano-liquid chromatography-tandem mass spectrometry, with peptide identification by Mascot software and an in-house mucin database. All diagnostic evaluations were blinded to proteomics results. Histology was required to confirm the presence/absence of malignant transformation. All statistical tests were two-sided.

RESULTS

Proteomic mucin profiling proved statistically significantly more accurate (97.5%; 95% confidence interval [CI] = 90.3% to 99.6%) than cytology (71.4%; 95% CI = 59.8% to 80.9%; P < .001) and cyst fluid CEA (78.0%; 95% CI = 65.0% to 87.3%; P < .001) in identifying the 37 (out of 79; 46.8%) lesions with malignant potential (ie, premalignant or malignant tumors). The accuracy of proteomics was nearly identical (96.6% vs 98.0%) between the discovery (n = 29) and validation (n = 50) cohorts. Furthermore, mucin profiling predicted malignant transformation, present in 16 out of 29 (discovery cohort: 9, validation cohort: 20) lesions with available histology, with 89.7% accuracy (95% CI = 71.5% to 97.3%) (for the validation cohort only: 95.0%; 95% CI = 73.1% to 99.7%). This markedly exceeded corresponding results for cytology (51.7%; 95% CI = 32.9% to 70.1%; P = .003) and CEA (57.1%; 95% CI = 34.4% to 77.4%; P = .02).

CONCLUSIONS

Proteomic cyst fluid mucin profiling robustly discriminates benign, premalignant, and malignant PCLs. Consequently, it may improve pancreatic cancer prevention and reduce the morbidity burden of unwarranted pancreatic surgery.

Proposal for a morphological classification of intraductal papillary neoplasm of the bile duct (IPN-B)

PURPOSE

We propose a morphological classification of intraductal papillary neoplasm of the bile duct (IPN-B).

METHODS

A retrospective analysis of 16 patients with IPN-B who had undergone surgical resection was conducted. These 16 cases were classified into three types based on the primary lesion's anatomical location: branch duct type (6 cases), main duct type (5 cases) and mixed type (5 cases). In this paper we have analyzed the characteristics of IPN-B according to our new classification.

RESULTS

All branch duct type IPN-B was located in the left lobe and 5 of them were resected by left hepatectomy without extrahepatic bile duct resection (EBDR). On the other hand, all patients with main duct and mixed type IPN-B underwent EBDR in addition to hepatectomy or pancreatoduodenectomy. Microscopically, 2 of 6 patients with branch duct type IPN-B had no malignant component and, in the remaining 4 patients, cancer invasion was restricted to within the ductal wall. There were no cases of branch duct type IPN-B with lymph node metastasis and superficial intraductal tumor spread. In contrast, all patients with main duct and mixed duct type IPN-B had the malignant component. In all cases, lymph node metastasis was not observed, but superficial intraductal tumor spread was frequently found in extrahepatic bile duct lesions: 3 of main duct type and 3 of mixed type. Four patients with superficial intraductal spread had non-curative resection due to a cancer-positive ductal margin. Most patients with IPN-B obtained a good prognosis, but two patients with a cancer-positive ductal margin developed local recurrence.

CONCLUSIONS

Our classification vividly reflects clinical and pathological characteristics of IPN-B and is useful to determine appropriate surgical strategy.

Regulated traffic of anion transporters in mammalian Brunner's glands: a role for water and fluid transport

The Brunner's glands of the proximal duodenum exert barrier functions through secretion of glycoproteins and antimicrobial peptides. However, ion transporter localization, function, and regulation in the glands are less clear. Mapping the subcellular distribution of transporters is an important step toward elucidating trafficking mechanisms of fluid transport in the gland. The present study examined 1) changes in the distribution of intestinal anion transporters and the aquaporin 5 (AQP5) water channel in rat Brunner's glands following second messenger activation and 2) anion transporter distribution in Brunner's glands from healthy and disease-affected human tissues. Cystic fibrosis transmembrane conductance regulator (CFTR), AQP5, sodium-potassium-coupled chloride cotransporter 1 (NKCC1), sodium-bicarbonate cotransporter (NBCe1), and the proton pump vacuolar ATPase (V-ATPase) were localized to distinct membrane domains and in endosomes at steady state. Carbachol and cAMP redistributed CFTR to the apical membrane. cAMP-dependent recruitment of CFTR to the apical membrane was accompanied by recruitment of AQP5 that was reversed by a PKA inhibitor. cAMP also induced apical trafficking of V-ATPase and redistribution of NKCC1 and NBCe1 to the basolateral membranes. The steady-state distribution of AQP5, CFTR, NBCe1, NKCC1, and V-ATPase in human Brunner's glands from healthy controls, cystic fibrosis, and celiac disease resembled that of rat; however, the distribution profiles were markedly attenuated in the disease-affected duodenum. These data support functional transport of chloride, bicarbonate, water, and protons by second messenger-regulated traffic in mammalian Brunner's glands under physiological and pathophysiological conditions.

The gastrointestinal mucus system in health and disease

Mucins--large, highly glycosylated proteins--are important for the luminal protection of the gastrointestinal tract. Enterocytes have their apical surface covered by transmembrane mucins and goblet cells produce the secreted gel-forming mucins that form mucus. The small intestine has a single unattached mucus layer, which in cystic fibrosis becomes attached, accounting for the intestinal manifestations of this disease. The stomach and colon have two layers of mucus; the inner layer is attached and the outer layer is less dense and unattached. In the colon, the outer mucus layer is the habitat for commensal bacteria. The inner mucus layer is impervious to bacteria and is renewed every hour by surface goblet cells. The crypt goblet cells have the ability to restitute the mucus layer by secretion, for example after an ischaemic challenge. Proteases of certain parasites and some bacteria can cleave mucins and dissolve the mucus as part of their pathogenicity. The inner mucus layer can, however, also become penetrable to bacteria by several other mechanisms, including aberrations in the immune system. When bacteria reach the epithelial surface, the immune system is activated and inflammation is triggered. This mechanism might occur in some types of ulcerative colitis.

Intraductal tubular neoplasms of the bile ducts

Although most tumors of the bile ducts are predominantly invasive, some have an exophytic pattern within the bile ducts; these intraductal papillary neoplasms usually have well-formed papillae at the microscopic level. In this study, however, we describe a novel type of intraductal neoplasm of the bile ducts with a predominantly tubular growth pattern and other distinctive features. Ten cases of biliary intraductal neoplasms with a predominantly tubular architecture were identified in the files of the Pathology Department at Memorial Sloan-Kettering Cancer Center from 1983 to 2006. For each of these cases we studied the clinical presentation, histologic and immunohistochemical features (9 cases only), and the clinical follow-up of the patients. Three male and 7 female patients (38 to 78 y) presented with obstructive jaundice or abdominal pain. Eight of the patients underwent a partial hepatectomy; 2 underwent a laparoscopic bile duct excision, followed by a pancreatoduodenectomy in one of them. The tumors range in size from 0.6 to 8.0 cm. The intraductal portions of the tumors (8 intrahepatic, 1 extrahepatic hilar, 1 common bile duct) were densely cellular and composed of back-to-back tubular glands and solid sheets with minimal papillary architecture. The cells were cuboidal to columnar with mild to moderate cytologic atypia. Foci of necrosis were present in the intraductal component in 6 cases. An extraductal invasive carcinoma component was present in 7 cases, composing <25% of the tumor in 4 cases, and >75% in 1 case. It was observed by immunohistochemical analysis that the tumor cells expressed CK19, CA19-9, MUC1, and MUC6 in most cases and that SMAD4 expression was retained. MUC2, MUC5AC, HepPar1, synaptophysin, chromogranin, p53, and CA125 were negative in all cases and most were negative for CEA-M and B72.3. Four patients were free of tumor recurrence after 7 to 85 months (average, 27 mo). Four patients with an invasive carcinoma component suffered metastases, 1 after local intraductal recurrence. However, the occurrence of metastasis in 3 of these patients was quite late (average, 52 mo). Intraductal tubular neoplasm of the bile ducts is a biliary intraductal neoplasm with a distinctive histologic pattern resembling the recently described intraductal tubulopapillary neoplasm of the pancreas. Immunohistochemical features are similar to those of other pancreatobiliary-type carcinomas. However, this tumor may be hard to recognize as intraductal because of its complex architecture. When the tumor is entirely intraductal, the outcome appears to be favorable, but metastases can occur when invasive carcinoma is present, even after many years.

Intraductal papillary neoplasm arising from peribiliary glands connecting with the inferior branch of the bile duct of the anterior segment of the liver

Intraductal papillary neoplasms of the bile duct are generally thought to arise from neoplastic papillary proliferation of epithelial cells lining the bile duct. We herein report a case with findings that strongly suggested that the biliary cystic tumor might have derived from a peribiliary gland. A 69-year-old female was found to have a cystic lesion with intracystic protrusions at the anterior segment of the right hepatic lobe and underwent hepatic anterior segment resection. Fluoroscopy of the resected specimen injected with contrast medium into the cyst revealed a connection between the cystic lesion and the bile ducts. The cyst was multilocular in appearance. On microscopic examination, the cyst was located within the portal tract of the inferior branch of the anterior segment and connected with the inferior branch of the bile duct. The wall of the hepatic cyst lacked an ovarian-like stroma. The tumor was composed of papillary and glandular components, and the tumor cells were similar to gastric foveolar and pyloric gland epithelia and regarded as adenoma. These tumor cells were positive for MUC 5AC, MUC6, and HIK1083. The tumor was finally diagnosed as an intraductal papillary neoplasm of the bile duct (adenoma, gastric type) arising from a peribiliary gland.

Mucins in inflammatory bowel diseases and colorectal cancer

The gastrointestinal tract is protected by a mucus barrier with both secreted and cell-surface mucins contributing to the exclusion of luminal microbes and toxins. Alterations in the structure and/or quantity of mucins alter the barrier function of mucus and could play roles in initiating and maintaining mucosal inflammation in inflammatory bowel diseases (IBD), and in driving cancer development in the intestine. The aim of this review is to focus on the roles of the mucins in IBD. The polymorphisms of mucin genes that have been associated with susceptibility to IBD, and alterations in mucin expression as well as factors that regulate production of the mucins in IBD, are summarized. Data from animal models of intestinal inflammation, which support the importance of mucins in IBD and cancer development, are also discussed.

Lactobacillus adhesion to mucus

Mucus provides protective functions in the gastrointestinal tract and plays an important role in the adhesion of microorganisms to host surfaces. Mucin glycoproteins polymerize, forming a framework to which certain microbial populations can adhere, including probiotic Lactobacillus species. Numerous mechanisms for adhesion to mucus have been discovered in lactobacilli, including partially characterized mucus binding proteins. These mechanisms vary in importance with the in vitro models studied, which could significantly affect the perceived probiotic potential of the organisms. Understanding the nature of mucus-microbe interactions could be the key to elucidating the mechanisms of probiotic adhesion within the host.

Epigenetic regulation of mucin genes in human cancers

Mucins are high molecular weight glycoproteins that play important roles in diagnostic and prognostic prediction and in carcinogenesis and tumor invasion. Regulation of expression of mucin genes has been studied extensively, and signaling pathways, transcriptional regulators, and epigenetic modification in promoter regions have been described. Detection of the epigenetic status of cancer-related mucin genes is important for early diagnosis of cancer and for monitoring of tumor behavior and response to targeted therapy. Effects of micro-RNAs on mucin gene expression have also started to emerge. In this review, we discuss the current views on epigenetic mechanisms of regulation of mucin genes (MUC1, MUC2, MUC3A, MUC4, MUC5AC, MUC5B, MUC6, MUC16, and MUC17) and the possible clinical applications of this epigenetic information.

Aberrant expression of TFF1, TFF2, and PDX1 and their diagnostic value in lobular endocervical glandular hyperplasia

Lobular endocervical glandular hyperplasia (LEGH) is a distinct benign glandular lesion expressing gastric gland mucous cell-type mucin (N-acetylglucosaminα1 → 4galactose → R [GlcNAcα1 → 4Gal → R]). To investigate histogenesis and diagnostic markers of LEGH, we examined the immunohistochemical expression profile of gastric surface mucous cell (MUC5AC and TFF1), gastric gland mucous cell (MUC6, TFF2, and GlcNAcα1 → 4Gal → R), gastric pyloric epithelial cell (PDX1), and endocervical cell (keratan sulfate) markers in normal endocervix samples and benign glandular lesions (nabothian cysts, tunnel clusters, and LEGHs). MUC5AC and MUC6 were expressed in normal endocervical mucosa and benign glandular lesions. TFF1, TFF2, GlcNAcα1 → 4Gal → R, and PDX1 were expressed only in LEGH. Keratan sulfate was expressed in normal endocervical mucosa and benign glandular lesions. In LEGH, gastric surface mucous cell and gastric gland mucous cell differentiation were demonstrated, and transdifferentiation from endocervical mucosa into gastric pyloric mucosa was suggested. In addition to GlcNAcα1 → 4Gal → R, TFF1, TFF2, and PDX1 are additional useful markers for LEGH.

Role of mucins in the skin during benign and malignant conditions

Skin-related diseases comprise a major health challenge to the practicing physician, and constitute a significant psychological, social and financial burden to the society. Further, skin cancer, especially non-melanoma skin cancer is currently the leading type of malignancy in the Western world. Given the huge burden of skin diseases, there is growing emphasis on understanding their pathophysiology, and towards their early detection. Mucins are high-molecular weight O- and N-linked glycoproteins that have emerged in recent years as important molecules in maintaining health and in promoting or protecting against inflammation and cancer. They have also begun to emerge as highly specific diagnostic and prognostic markers and novel therapeutic targets in several malignant disorders. However, their role in cutaneous pathologies has remained largely obscured. The present review provides the expression patterns and proposed role of mucins in the healthy skin and various benign and malignant skin diseases. The review has immense clinical significance as the availability of highly specific reagents including monoclonal antibodies against mucins makes them extremely attractive targets for specific diagnosis and/or immunotherapy of benign and malignant cutaneous diseases.

Pancreatic lymphoepithelial cysts express CEA and can contain mucous cells: potential pitfalls in the preoperative diagnosis

Pancreatic lymphoepithelial cysts are rare benign cysts that cannot be reliably differentiated from neoplastic mucinous cysts preoperatively. Although elevated cyst fluid carcinoembryonic antigen (CEA) levels support a diagnosis of a mucinous cyst, the finding of increased CEA levels in lymphoepithelial cysts prompted this study. Nine resected lymphoepithelial cysts were examined for expression of CEA, carbohydrate antigen (CA) 19-9, CK7, p63, PAS-D and a panel of mucins. The pathology data were correlated with clinical information, including serum, cyst fluid and imaging studies. By computed tomography scan, although most lymphoepithelial cysts appeared cystic, 23% were described as masses. The endoscopic ultrasound findings were variable, but the lymphoepithelial cysts tended to be hypoechoic cystic lesions or masses. On cytology, 44% of the cysts had squamous cells, 67% had glandular cells and 56% had atypical cells. The cysts were resected because of size ≥3 cm (89%), symptoms (44%) and/or elevated cyst fluid CEA levels (33%). The cyst fluid CEA levels in the three cysts tested were >450 ng/ml. Histopathologically, all cysts were lined by mature, stratified squamous-type cells and produced keratin. Mucous cells were present in 78% of the cysts. The immunohistochemical profile of the squamous lining was CK7+, p63+, MUC1+, MUC4+, MUC2-, MUC5AC- and MUC6-. Even though lymphoepithelial cysts are lined by squamous-type epithelium, all our resected lymphoepithelial cysts expressed CEA and/or CA19-9, many contained mucous cells, and three exhibited markedly elevated cyst fluid CEA levels. Although cyst fluid CEA levels >200 ng/ml support the diagnosis of mucinous neoplasms, this study emphasizes the need for clinicians and pathologists to recognize that lymphoepithelial cysts can mimic neoplastic mucinous cysts clinically, radiographically and on cyst fluid CEA analysis.

Short rare MUC6 minisatellites-5 alleles influence susceptibility to gastric carcinoma by regulating gene

The human MUC6 gene, which is reported to be expressed in the stomach and gall bladder, is clustered on chromosome 11p15.5 with other secreted mucins. In this study, the genomic structure of MUC6 has been analyzed and five VNTR (minisatellites; MS1-MS5) were identified. These minisatellites were analyzed in genomic DNA extracted from 1,103 controls, 470 gastric cancer patients, and multigenerational families. Five novel minisatellites were found to be polymorphic and transmitted through meiosis by Mendelian inheritance in families. We evaluated allelic variation in these minisatellites to determine if such variation affected the susceptibility to gastric cancer. A significant association (odds ratio [OR]=7.08) between short rare MUC6-MS5 alleles and relative risks were observed for gastric cancer (95% confidence interval [CI], 1.43-35.19; P=0.005). To investigate the function of minisatellite alleles of MUC6-MS5, we examined the effects on gene expression from luciferase reporters when inserted with minisatellites. Interestingly, when the shortest allele (7TR) was inserted in the promoter, the expression level decreased over 20-fold (P<0.001) in normal and cancer cell lines. Furthermore, the cancer-specific rare allele (TR8) also showed decreased expression levels in cancer cells. Therefore, we suggest that the short rare MUC6-MS5 alleles may be related to cancer development by the regulation of MUC6 expression.

An immunohistochemical profile of the so-called bile duct adenoma: clues to pathogenesis

The so-called bile duct adenoma and peribiliary glands are characterized by the expression of two foregut antigens (designated D10 and 1F6) and secretion of acid mucin. On account of this similarity in phenotype and their frequent close association with a large caliber bile duct, it was earlier suggested that bile duct adenoma represent a peribiliary gland hamartoma. Here, we compare the expression of 13 tissue antigens in bile duct adenomas, other benign bile duct lesions, and various foregut-derived tissues, to further investigate the bile duct adenoma phenotype and pathogenesis. Antibodies to 4 intestinal mucins, 3 cytokeratins, and CDX2, were not informative. Five foregut antigens (D10, 1F6, MUC6, MUC5AC, and TFF2) and secretion of acid mucin were of use in distinguishing bile duct adenoma from other hepatic lesions. 1F6 and MUC6 were normally present in bile ductules and canals of Hering, whereas the epithelium lining the larger bile ducts stained focally for D10, MUC5AC, MUC6, or TFF2 in, respectively, 21%, 36%, 43%, and 100% of the livers examined. Thirty-six bile duct adenomas examined were distinguished by expression of MUC6 (94% of bile duct adenoma), MUC5AC (90%), TFF2 (80%), D10 (67%), and 1F6 (61%), and varying degrees of acid mucin secretion (100%). Of 30 bile duct adenoma tested for all 5 antigens, 40% expressed all 5, 27% expressed 4, 17% expressed 3, 13% expressed 2, and 1 expressed only MUC6. Peribiliary glands invariably expressed D10, 1F6, MUC6, and TFF2, and showed acid mucin secretion, with MUC5AC present in the inflamed peribiliary glands of 3/4 livers with recurrent pyogenic cholangitis, but none of the glands of the other 23 normal or diseased livers tested. The acini of pyloric gland metaplasia in gallbladder and terminal ileum also stained for D10, 1F6, MUC6, and TFF2, with MUC5AC focally present in the gastric foveolar metaplasia overlying the pyloric gland metaplasia but not in the metaplastic glands. MUC6 was expressed in 92% of ductular reactions, 1F6 in 42%, and D10 in 25%. Focal expression of MUC6, or TFF2 was observed in 1 or 2 examples of 14 von Meyenburg complexes and 6 polycystic livers, with staining for acid mucin generally obvious only in the glycocalyx of the epithelium of these two types of lesions. The distinguishing feature of so-called bile duct adenoma is their display of the same phenotype as pyloric gland metaplasia. It is concluded that they develop as a localized biliary healing response equivalent to the function of a peribiliary gland or pyloric gland metaplasia in the foregut.