Gastric-type mucin and TFF-peptide expression in Barrett's oesophagus is disturbed during increased expression of MUC2

Molecules involved in the development of Barrett's esophagus phenotype in chronic eosinophilic esophagitis

This paper aims to investigate the molecules involved in development of Barrett's esophagus (BE) in human eosinophilic esophagitis (EoE). Histopathological, immunohistochemical, real-time PCR Immuno blot, and ELISA analyses are performed to identify the signature genes and proteins involved in the progression of BE in EoE. We detected characteristic features of BE like intermediate columnar-type epithelial cells, induced BE signature genes like ErbB3, CDX1, ErbB2IP in the esophageal mucosa of patients with EoE. In addition, we had observed several BE-associated proteins such as TFF3, p53 and the progression markers like EGFR, p16, MICA, MICB, and MHC molecules in esophageal biopsies of patients with chronic EoE. Interestingly, we also detected mucin-producing columnar cells and MUC-2, MUC-4, and MUC5AC genes and proteins along with induced IL-9 in patients with chronic EoE. A strong correlation of IL-9 with mucin genes is observed that implicated a possible role for IL-9 in the transformation of esophageal squamous epithelial cells to columnar epithelial cells in patients with EoE. These findings indicate that IL-9 may have an important role in BE development in patients with chronic EoE. We also discovered that IL-9 stimulates mucin-producing and barrier cell transcripts and proteins such CK8/18, GATA4, SOX9, TFF1, MUC5AC, and tight junction proteins in primary esophageal epithelial cells when exposed to IL-9. Taken together, these findings provide evidence that indeed IL-9 has a role in the initiation and progression of BE characteristics like development of mucin-producing columnar epithelial cells in patients with chronic EoE.NEW & NOTEWORTHY Intermediate columnar-type epithelial cells are observed in biopsies of patients with EoE. Induced BE signature genes (CK8/18, CDX1 GATA4, SOX9, and Occludin) were observed in patients with chronic EoE. Induction of IL-9 and its correlation with eosinophils mucin-producing genes and proteins was observed in patients with EoE. Induced IL-9 may be responsible for the development of BE in patients with chronic EoE.

Transcription factor-mediated intestinal metaplasia and the role of a shadow enhancer

Here, Singh et al. show extensive but selective recruitment of intestinal enhancers by CDX2 in gastric cells and that HNF4A-mediated ectopic CDX2 expression in the stomach occurs through a conserved shadow cis-element. These findings identify mechanisms for TF-driven intestinal metaplasia and a likely pathogenic TF hierarchy.

Barrett's esophagus (BE) and gastric intestinal metaplasia are related premalignant conditions in which areas of human stomach epithelium express mixed gastric and intestinal features. Intestinal transcription factors (TFs) are expressed in both conditions, with unclear causal roles and cis-regulatory mechanisms. Ectopic CDX2 reprogrammed isogenic mouse stomach organoid lines to a hybrid stomach–intestinal state transcriptionally similar to clinical metaplasia; squamous esophageal organoids resisted this CDX2-mediated effect. Reprogramming was associated with induced activity at thousands of previously inaccessible intestine-restricted enhancers, where CDX2 occupied DNA directly. HNF4A, a TF recently implicated in BE pathogenesis, induced weaker intestinalization by binding a novel shadow Cdx2 enhancer and hence activating Cdx2 expression. CRISPR/Cas9-mediated germline deletion of that cis-element demonstrated its requirement in Cdx2 induction and in the resulting activation of intestinal genes in stomach cells. dCas9-conjugated KRAB repression mapped this activity to the shadow enhancer's HNF4A binding site. Altogether, we show extensive but selective recruitment of intestinal enhancers by CDX2 in gastric cells and that HNF4A-mediated ectopic CDX2 expression in the stomach occurs through a conserved shadow cis-element. These findings identify mechanisms for TF-driven intestinal metaplasia and a likely pathogenic TF hierarchy.

Hybrid Stomach-Intestinal Chromatin States Underlie Human Barrett's Metaplasia

BACKGROUND & AIMS

Tissue metaplasia is uncommon in adults because established cis-element programs resist rewiring. In Barrett's esophagus, the distal esophageal mucosa acquires a predominantly intestinal character, with notable gastric features, and is predisposed to developing invasive cancers. We sought to understand the chromatin underpinnings of Barrett's metaplasia and why it commonly displays simultaneous gastric and intestinal properties.

METHODS

We profiled cis-regulatory elements with active histone modifications in primary human biopsy materials using chromatin immunoprecipitation followed by DNA sequencing. Mutations in Barrett's esophagus were examined in relation to tissue-specific enhancer landscapes using a random forest machine-learning algorithm. We also profiled open chromatin at single-cell resolution in primary Barrett's biopsy specimens using the assay for transposase-accessible chromatin. We used 1- and 2-color immunohistochemistry to examine protein expression of tissue-restricted genes.

RESULTS

Barrett's esophagus bears epigenome fingerprints of human stomach and intestinal columnar, but not esophageal squamous, epithelia. Mutational patterns were best explained as arising on the epigenome background of active gastric cis-elements, supporting the view that adjoining stomach epithelium is a likely tissue source. Individual cells in Barrett's metaplasia coexpress gastric and intestinal genes, reflecting concomitant chromatin access at enhancers ordinarily restricted to one or the other epithelium. Protein expression of stomach-specific mucins; CLDN18; and a novel gastric marker, ANXA10, showed extensive tissue and subclonal heterogeneity of dual stomach-intestinal cell states.

CONCLUSIONS

These findings reveal mixed and dynamic tissue-restricted chromatin states and phenotypic heterogeneity in Barrett's esophagus. Pervasive intragland variation argues against stem-cell governance of this phenotype.

Molecular Profile of Barrett's Esophagus and Gastroesophageal Reflux Disease in the Development of Translational Physiological and Pharmacological Studies

Barrett's esophagus (BE) is a premalignant condition caused by gastroesophageal reflux disease (GERD), where physiological squamous epithelium is replaced by columnar epithelium. Several in vivo and in vitro BE models were developed with questionable translational relevance when implemented separately. Therefore, we aimed to screen Gene Expression Omnibus 2R (GEO2R) databases to establish whether clinical BE molecular profile was comparable with animal and optimized human esophageal squamous cell lines-based in vitro models. The GEO2R tool and selected databases were used to establish human BE molecular profile. BE-specific mRNAs in human esophageal cell lines (Het-1A and EPC2) were determined after one, three and/or six-day treatment with acidified medium (pH 5.0) and/or 50 and 100 µM bile mixture (BM). Wistar rats underwent microsurgical procedures to generate esophagogastroduodenal anastomosis (EGDA) leading to BE. BE-specific genes (keratin (KRT)1, KRT4, KRT5, KRT6A, KRT13, KRT14, KRT15, KRT16, KRT23, KRT24, KRT7, KRT8, KRT18, KRT20, trefoil factor (TFF)1, TFF2, TFF3, villin (VIL)1, mucin (MUC)2, MUC3A/B, MUC5B, MUC6 and MUC13) mRNA expression was assessed by real-time PCR. Pro/anti-inflammatory factors (interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-13, tumor necrosis factor α, interferon γ, granulocyte-macrophage colony-stimulating factor) serum concentration was assessed by a Luminex assay. Expression profile in vivo reflected about 45% of clinical BE with accompanied inflammatory response. Six-day treatment with 100 µM BM (pH 5.0) altered gene expression in vitro reflecting in 73% human BE profile and making this the most reliable in vitro tool taking into account two tested cell lines. Our optimized and established combined in vitro and in vivo BE models can improve further physiological and pharmacological studies testing pathomechanisms and novel therapeutic targets of this disorder.

Notch Signaling Pathway Is Inhibited in the Development of Barrett's Esophagus: An In Vivo and In Vitro Study

OBJECTIVE

To explore the role of Notch signaling in the development of Barrett's esophagus.

METHODS

Patients with esophagectomy and gastric interposition were recruited as a human model of gastroesophageal reflux disease. The expressions of Notch signaling genes in normal esophagus from surgical specimen and columnar metaplasia in the esophageal remnant after esophagectomy were evaluated by real time quantitative Polymerase Chain Reaction (RT-qPCR) and immunohistochemistry (IHC). For in vitro experiments, Het-1A cells were treated with hydrochloric acid, deoxycholic acid, mixture of hydrochloric acid and deoxycholic acid, or Notch1-siRNA, and expressions of Notch1, Hes1, MUC2, and K13 were evaluated via RT-qPCR and western blot.

RESULTS

Samples were obtained from 36 patients with columnar metaplasia in the esophageal remnant. Both IHC and RT-qPCR indicated that Notch1 and Hes1 expressions were significantly higher in normal esophagus than that in metaplasia. Hydrochloric acid and deoxycholic acid suppressed Notch1, Hes1, and K13 expressions, in concert with increasing MUC2 expressions. Notch inhibition by Notch1-siRNA contributed to the downregulation of Notch1, Hes1, and K13 expressions, whereas MUC2 expression was enhanced.

CONCLUSIONS

Both hydrochloric acid and deoxycholic acid could suppress Notch signaling pathway in esophageal epithelial cells, and inhibited Notch signaling has important functions in the development of Barrett's esophagus.

Goblet Cell Ratio in Combination with Differentiation and Stem Cell Markers in Barrett Esophagus Allow Distinction of Patients with and without Esophageal Adenocarcinoma

The increasing incidence of esophageal adenocarcinoma (EAC) is mirrored by the increasing prevalence of Barrett esophagus, a precursor lesion resulting in a large number of individuals "at risk" for this lethal malignancy. Among patients with Barrett esophagus, only about 0.3% annually will develop EAC. Because large numbers of patients are followed in endoscopic surveillance, there is a need for risk prediction among a growing population of patients with Barrett esophagus. We identified four potential biomarkers from an inflammation (IL1β)-dependent mouse model of Barrett esophagus and tested them in 189 patients with Barrett esophagus with and without high-grade dysplasia (HGD)/early cancer (T1). The primary goal was to distinguish patients with Barrett esophagus with no evidence of dysplasia from those with dysplasia. Increasing stem cell marker LGR5 and niche cell marker DCLK1 and decreasing differentiation marker (secretory mucus cells, TFF2⁺ cells) correlated with elevated tumor score in the mouse. Having outlined the origin of those markers in the Barrett esophagus mouse model, we showed the applicability for human Barrett esophagus. We compared 94 patients with nondysplastic Barrett esophagus tissue with 95 patients with Barrett esophagus and HGD or early cancer. Low levels of TFF2 (AUC 87.2%) provided the best discrimination between nondysplastic Barrett esophagus and Barrett esophagus with cancer, followed by high levels of DCLK1 (AUC 83.4%), low goblet cell ratio (AUC 79.4%), and high LGR5 (AUC 71.4%). The goblet cell ratio, rather than the presence of goblet cells per se, was found to be an important discriminator. These findings may be useful in developing future risk prediction models for patients with Barrett esophagus and ultimately to improve EAC surveillance. Cancer Prev Res; 10(1); 55-66. ©2016 AACR.

Trefoil Factor Expression in a Human Model of the Early Stages of Barrett's Esophagus

BACKGROUND

Trefoil proteins are believed to have an important role in mucosal protection and repair in the gastrointestinal tract. They are well recognized in Barrett's esophagus and considered a potential biomarker for the condition. Metaplasia occurring in the esophageal remnant after esophagectomy is a human model for the early stages of development of Barrett's esophagus.

AIMS

To assess expression of trefoil proteins in post-esophagectomy columnar epithelium and to use trefoils as a molecular tool to understand regenerative mucosa in the esophagus.

METHODS

Patients with columnar metaplasia in the esophageal remnant were recruited from a large esophago-gastric cancer center. Trefoil factor expression was determined using immunohistochemical techniques.

RESULTS

Samples were obtained from 37 patients. TFF1 and TFF2 were expressed by all samples in a similar pattern to that described in studies of sporadic Barrett's esophagus. TFF3 was less widely expressed and was significantly associated with time elapsed between surgery and endoscopy. Median time from surgery to endoscopy was 8.1 years for patients with TFF3 expression versus 3.4 years for those without (p = 0.004).

CONCLUSIONS

Widespread expression of trefoils in this environment suggests that these proteins have an important role in development of Barrett's metaplasia. TFF3 expression may be absent in the early stages of metaplasia and may represent more established columnar epithelium. Biopsy samples from post-esophagectomy patients provide a valuable resource to study the early stages of Barrett's esophagus.

The Barrett's Gland in Phenotype Space

Barrett's esophagus is characterized by the erosive replacement of esophageal squamous epithelium by a range of metaplastic glandular phenotypes. These glandular phenotypes likely change over time, and their distribution varies along the Barrett's segment. Although much recent work has addressed Barrett's esophagus from the genomic viewpoint-its genotype space-the fact that the phenotype of Barrett's esophagus is nonstatic points to conversion between phenotypes and suggests that Barrett's esophagus also exists in phenotype space. Here we explore this latter concept, investigating the scope of glandular phenotypes in Barrett's esophagus and how they exist in physical and temporal space as well as their evolution and their life history. We conclude that individual Barrett's glands are clonal units; because of this important fact, we propose that it is the Barrett's gland that is the unit of selection in phenotypic and indeed neoplastic progression. Transition between metaplastic phenotypes may be governed by neutral drift akin to niche turnover in normal and dysplastic niches. In consequence, the phenotype of Barrett's glands assumes considerable importance, and we make a strong plea for the integration of the Barrett's gland in both genotype and phenotype space in future work.

Barrett oesophagus: lessons on its origins from the lesion itself

Barrett oesophagus develops when the lower oesophageal squamous epithelium is replaced with columnar epithelium, which shows both intestinal and gastric differentiation. No consensus has been reached on the origin of Barrett oesophagus. Theories include a direct origin from the oesophageal-stratified squamous epithelium, or by proximal migration of the gastric cardiac epithelium with subsequent intestinalization. Variations of this theory suggest the origin is a distinctive cell at the squamocolumnar junction, the oesophageal gland ducts, or circulating bone-marrow-derived cells. Much of the supporting evidence comes from experimental models and not from studies of Barrett mucosa. In this Perspectives article, we look at the Barrett lesion itself: at its phenotype, its complexity, its clonal architecture and its stem cell organization. We conclude that Barrett glands are unique structures, but share many similarities with gastric glands undergoing the process of intestinal metaplasia. We conclude that current evidence most strongly supports an origin from stem cells in the cardia.

Expression and localization of trefoil factor family genes in rat submandibular glands

The trefoil factor (TFF) family, which comprises TFF1, TFF2 and TFF3, plays an essential role in epithelial regeneration within the gastrointestinal tract. All three TFFs are present in human saliva; TFF3 is the predominant trefoil peptide. Little is known about the expression and tissue distribution of TFFs in rats, which are commonly used as a model system for human studies. We investigated the localization of the TFF genes that encode secretory peptides in rat submandibular glands (SMG). All three TFFs were expressed in rat SMG, although their location varied. Substantial amounts of TFF1 were detected only in the cytoplasm of epithelial cells in the SMG granular convoluted tubules (GCT), while TFF2 and TFF3 were widely distributed in the cytoplasm of epithelial cells of intercalated ducts (ID), striated ducts (SD) and interlobular ducts (ILD). The three TFFs also were detected especially in the lumens of the SD and ILD. Semi-quantitative RT-PCR and in situ hybridization experiments confirmed TFF1, TFF2 and TFF3 mRNA expressions in the SMG. Greater expression of TFF peptides and mRNA was observed in male rats than in females. The broad expression of TFFs in rat SMG cells and lumens suggests that TFFs function in this organ by their secretion into the duct lumens. We also found differences in TFF expression profiles between rat and human SMG; therefore, caution should be exercised when using rats as a model for human TFF studies.

Bile acid and inflammation activate gastric cardia stem cells in a mouse model of Barrett-like metaplasia

Esophageal adenocarcinoma (EAC) arises from Barrett esophagus (BE), intestinal-like columnar metaplasia linked to reflux esophagitis. In a transgenic mouse model of BE, esophageal overexpression of interleukin-1β phenocopies human pathology with evolution of esophagitis, Barrett-like metaplasia and EAC. Histopathology and gene signatures closely resembled human BE, with upregulation of TFF2, Bmp4, Cdx2, Notch1, and IL-6. The development of BE and EAC was accelerated by exposure to bile acids and/or nitrosamines, and inhibited by IL-6 deficiency. Lgr5(+) gastric cardia stem cells present in BE were able to lineage trace the early BE lesion. Our data suggest that BE and EAC arise from gastric progenitors due to a tumor-promoting IL-1β-IL-6 signaling cascade and Dll1-dependent Notch signaling.

Whole genome expression array profiling highlights differences in mucosal defense genes in Barrett's esophagus and esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) has become a major concern in Western countries due to rapid rises in incidence coupled with very poor survival rates. One of the key risk factors for the development of this cancer is the presence of Barrett's esophagus (BE), which is believed to form in response to repeated gastro-esophageal reflux. In this study we performed comparative, genome-wide expression profiling (using Illumina whole-genome Beadarrays) on total RNA extracted from esophageal biopsy tissues from individuals with EAC, BE (in the absence of EAC) and those with normal squamous epithelium. We combined these data with publically accessible raw data from three similar studies to investigate key gene and ontology differences between these three tissue states. The results support the deduction that BE is a tissue with enhanced glycoprotein synthesis machinery (DPP4, ATP2A3, AGR2) designed to provide strong mucosal defenses aimed at resisting gastro-esophageal reflux. EAC exhibits the enhanced extracellular matrix remodeling (collagens, IGFBP7, PLAU) effects expected in an aggressive form of cancer, as well as evidence of reduced expression of genes associated with mucosal (MUC6, CA2, TFF1) and xenobiotic (AKR1C2, AKR1B10) defenses. When our results are compared to previous whole-genome expression profiling studies keratin, mucin, annexin and trefoil factor gene groups are the most frequently represented differentially expressed gene families. Eleven genes identified here are also represented in at least 3 other profiling studies. We used these genes to discriminate between squamous epithelium, BE and EAC within the two largest cohorts using a support vector machine leave one out cross validation (LOOCV) analysis. While this method was satisfactory for discriminating squamous epithelium and BE, it demonstrates the need for more detailed investigations into profiling changes between BE and EAC.

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.

A novel dietary-related model of esophagitis and Barrett's esophagus, a premalignant lesion

Barrett's esophagus (BE) is a premalignant lesion in which columnar epithelium (containing goblet cells) replaces esophageal squamous cells. Previous evidence suggested that hydrophobic bile acids and zinc deficiency each play a role in BE development. We fed wild-type C57BL/6 mice a zinc-deficient diet containing the hydrophobic bile acid, deoxycholic acid for various times up to 152 days. All mice fed this diet developed esophagitis by 69 days on the diet and 63% of the mice on this diet for 88 to 152 days also developed a BE-like lesion. Esophageal tissues showed thickened mucosa, increased proliferation, and increased expression of markers associated with oxidative and nitrosative stress. The newly formed BE-like lesions expressed Mucin-2, a marker of columnar differentiation. They also showed translocation of the p65 subunit of nuclear factor-kappaB and beta -catenin to the nucleus and typical histological changes associated with BE lesions. This mouse model of esophagitis and BE is expected to contribute to a deeper understanding of BE pathogenesis and to strategies for prevention of BE progression to cancer.

Identification of Fn14/TWEAK receptor as a potential therapeutic target in esophageal adenocarcinoma

Given the poor survival rate and efficacy of current therapy for esophageal adenocarcinoma (EAC), there is a need to identify and develop new therapeutic targets for treatment. Microarray analysis (Affymetrix U133A GeneChips, Robust Multi-Chip Analysis) was used to expression profile 11 normal squamous and 18 Barrett's esophagus biopsies, 7 surgically resected EACs and 3 EAC cell lines. Two hundred transcripts representing potential therapeutic targets were identified using the following criteria: significant overexpression in EAC by analysis of variance (p = 0.05, Benjamini Hochberg false discovery rate); 3-fold increase in EAC relative to normal and Barrett's esophagus and expression in at least 2 of the 3 EAC cell lines. From the list of potential targets we selected TNFRSF12A/Fn14/TWEAK receptor, a tumor necrosis factor super-family receptor, for further validation based on its reported role in tumor cell survival and potential as a target for therapy. Fn14 protein expression was confirmed in SEG-1 and BIC-1 cell lines, but Fn14 was not found to affect tumor cell survival after exposure to chemotherapeutics as expected. Instead, a novel role in EAC was discovered in transwell assays, in which modulating Fn14 expression affected tumor cell invasion. Fn14's potential as a therapeutic target was further supported by immunohistochemistry on a tissue microarray of patient samples that showed that Fn14 protein expression increased with disease progression in EAC.

Predictors for squamous re-epithelialization of Barrett's esophagus after endoscopic biopsy

BACKGROUND AND AIM

Acid suppressive therapy has been reported to regress Barrett's esophagus. However, it is still controversial as to whether all Barrett's esophagus patients respond to this therapy. The factors that might facilitate newly developed squamous re-epithelialization after biopsy excision of Barrett's mucosa were evaluated to identity individuals who may favorably respond to the regression therapy.

METHODS

Two hundred and forty-seven biopsy sites from 185 patients with Barrett's esophagus were examined by endoscopy to investigate possible squamous re-epithelialization of Barrett's mucosa after endoscopic biopsy. Before endoscopic examination, all participants were requested to answer questionnaires concerning sociodemographic characteristics, lifestyle habits and drugs usage. The mucin phenotype, Cdx2 expression, cyclooxygenase-2 expression, cellular proliferation and apoptosis of Barrett's mucosa were immunohistochemically investigated in the biopsy samples taken from Barrett's esophagus. The influence of these factors on the newly developed squamous re-epithelialization of Barrett's mucosa after endoscopic biopsy excision was evaluated.

RESULTS

By multivariate analysis, the independent factors that favored squamous re-epithelialization were the gastric mucin predominant phenotype of Barrett's mucosa and the absence of Cdx2 protein expression. In Barrett's mucosa with the gastric predominant mucin phenotype, proton pump inhibitor administration, the absence of reflux esophagitis and a low proliferating cell nuclear antigen index were found to be independent predictors for squamous re-epithelialization.

CONCLUSIONS

The absence of the intestinal predominant mucin phenotype was a positive predictor for newly developed squamous re-epithelialization at the site of biopsy of Barrett's mucosa. Only Barrett's esophagus with the gastric predominant mucin phenotype may predict a favorable response to acid suppressive therapy.

Tissue localization of human trefoil factors 1, 2, and 3

Trefoil factors (TTFs) are small, compact proteins coexpressed with mucins in the gastrointestinal tract. Three trefoil factors are known in mammals: TFF1, TFF2, and TFF3. They are implicated to play diverse roles in maintenance and repair of the gastrointestinal channel. We compared the expression pattern of the three trefoil factors analyzing mRNA from a panel of 20 human tissues by conventional reverse transcriptase (RT) PCR and, in addition, by real-time PCR. These findings were supported by immunohistochemical analysis of paraffin-embedded human tissues using rabbit polyclonal antibodies raised against these factors. TFF1 showed highest expression in the stomach and colon, whereas TFF2 and TFF3 showed highest expression in stomach and colon, respectively. All three TFFs were found in the ducts of pancreas. Whereas TFF2 was found to be restricted to these two tissues, the structurally more closely related TFF1 and TFF3 showed a more general tissue distribution and were found to colocalize on an array of mucosal surfaces. This is the first thorough parallel description of the tissue distribution of TFFs in normal tissues, and it provides a baseline for similar analysis in diseased tissues.

Localization of TFF3 peptide in human esophageal submucosal glands and gastric cardia: differentiation of two types of gastric pit cells along the rostro-caudal axis

TFF3 (trefoil factor family 3), which is a major secretory product of the gastric antrum and the intestine, but which is nearly absent in the gastric corpus, plays a key role in the maintenance of mucosal integrity. Here, we have systematically investigated TFF3 expression in the esophagus and gastric cardia by the use of reverse transcription/polymerase chain reaction (RT-PCR) analysis and immunohistochemistry. Synthesis of TFF3, but not TFF1 or TFF2, is detectable in esophageal submucosal glands. The stratified squamous epithelium is devoid of TFF synthesis. Prominent TFF3 expression starts at the Z-line with a sharply decreasing gradient toward the cardia. Immunohistochemistry has localized TFF3 to surface mucous cells of the proximal cardia. TFF3 distribution differs characteristically from that of TFF1 (secreted primarily by superficial surface mucous cells), whereas TFF3, together with the mucin MUC5AC, is also found in deeper lying cells toward the isthmus. This is the first report of TFF3 as a typical secretory peptide of esophageal submucosal glands and gastric cardia. The different expression patterns of TFF3 and TFF1 in the cardia suggest a stepwise maturation of surface mucous cells from TFF3/MUC5AC-positive cells close to the isthmus to TFF1/TFF3/MUC5AC-positive cells at the pit. The gradient of TFF3 expression along the gastric rostro-caudal axis defines two types of gastric pit cells: those secreting TFF3 in the cardia and the antrum and those nearly devoid of TFF3 synthesis in the corpus. This indicates the special requirement, particularly of the esophagogastric junction, for TFF3-triggered protection and repair.

The expression of MUC4 and MUC5AC is related to the biologic malignancy of intraductal papillary mucinous neoplasms of the pancreas

OBJECTIVE

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas show heterogeneous proliferations with latent malignancy. Mucins (MUC) are high-molecular-weight glycoproteins, with an aberrant expression profile in various malignancies. Recently, MUC4 and MUC5AC expressions have been demonstrated to correlate with the unfavorable and the favorable prognosis of pancreatic duct cell carcinoma, respectively. However, little is known about these mucin expressions in IPMNs.

METHODS

To clarify the role of MUC4 and MUC5AC expressions in IPMNs, the expression profiles of MUC4 and MUC5AC were investigated in 50 lesions from 17 specimens with 16 IPMNs by immunohistochemistry, using each of their specific antibodies.

RESULTS

The expression of MUC4 was found in the lesions ranging from adenoma to cancer lesions of IPMNs, whereas it was undetectable in normal and hyperplastic lesions. Frequent expression of MUC4 is found in the higher grade of IPMNs (borderline and cancer lesions; 16/18 lesions, 94%). The differences were independently significant (P < 0.001) when the cutoff point was set between adenoma and borderline IPMNs. Similarly, frequent expression of MUC5AC was detected in the lesions from adenoma to cancer of IPMNs (32/34, 94%), whereas no intense expression was detected in normal or hyperplastic lesions. The significant difference was found when the cutoff point was set between hyperplasia and adenoma of IPMNs (P < 0.001).

CONCLUSIONS

These results indicated that the expressions of MUC4 and MUC5AC are potential markers to distinguish adenoma or above malignant lesions of IPMNs from lesser malignant ones, respectively.

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.

Gastric and intestinal differentiation in Barrett's metaplasia and associated adenocarcinoma

Intestinal metaplasia is a prerequisite criterion for the diagnosis of Barrett's metaplasia and the sole columnar esophageal lining associated with malignancy. It is recognized by the presence of goblet cells, but columnar non-goblet elements, producing gastric or intestinal proteins, are the prevalent cell population. The cellular heterogeneity of Barrett's metaplasia is well documented but the relationship between the distinct cell subtypes and neoplasia is unclear. Our aim was to clarify the relationship between the different metaplastic populations and malignancy in order to investigate putative markers for risk stratification of Barrett's patients. We studied 46 columnar-lined esophageal segments, 15 with associated adenocarcinoma. The presence of the gastric, MUC5AC and MUC6, and the intestinal, MUC2, proteins was evaluated in metaplastic (columnar and goblet) and neoplastic cells. In neoplasia MUC5AC and MUC6 were detected in 100% and 86.6% of the cases, respectively. In metaplasia there were no differences in MUC5AC and MUC6 immunoreactivity, between cases with and without associated neoplasia, except for goblet elements producing MUC6 that were exclusive of metaplasia adjacent to adenocarcinoma (P < 0.05). MUC2 was present in 86.6% of the neoplasia. In metaplasia it was restricted to Barrett's cases and was more frequent in areas with intestinal metaplasia. Columnar-lined esophagus without intestinal metaplasia did not express MUC2. Our study suggests a relationship between the metaplastic population with gastric phenotype and malignancy, and points to the involvement of columnar as well as goblet elements in tumorigenesis. The association between goblet cells aberrantly producing MUC6 and the presence of neoplasia suggests they may be useful for risk stratification.

Cyclooxygenase-2 expression and cell proliferation are increased in MUC2-positive area of columnar-lined esophagus

Columnar-lined esophagus is composed of intestinal type and gastric type epithelium. Only the specialized or intestinal type columnar epithelium is susceptible to the development of esophageal adenocarcinoma. The aim of the present paper was to evaluate the expression of cyclooxygenase (COX) and microsomal prostaglandin E synthase (mPGES) in gastric-type and intestinal-type metaplasia in columnar-lined esophagus and compare these with cell proliferation. Biopsy specimens of 30 columnar-lined esophagus patients were collected, and immunohistochemistry was performed for secretory mucins (MUC2, MUC5AC), COX, mPGES and cell proliferation (Ki-67). The MUC2-positive area had higher COX-2 expression and cell proliferation than the MUC5AC-positive area. There was a close correlation between COX-2 expression and cell proliferation. In contrast, the expression of COX-1, mPGES-1 and -2 was similar between intestinal metaplasia and gastric metaplasia. In conclusion, intestinal-type columnar-lined esophagus possesses COX-2 expression and a higher proliferation potential, suggesting that esophageal adenocarcinoma may arise from specialized columnar-lined esophagus.

Accurate discrimination of Barrett's esophagus and esophageal adenocarcinoma using a quantitative three-tiered algorithm and multimarker real-time reverse transcription-PCR

Esophageal adenocarcinoma (EA) is increasing faster than any other cancer in the U.S. In this report, we first show that EA can be distinguished from normal esophagus (NE) and esophageal squamous cell carcinoma by plotting expression values for EpCam, TFF1, and SBEM in three-dimensional Euclidean space. For monitoring progression of Barrett's esophagus (BE) to EA, we developed a highly sensitive assay for limited quantities of tissue whereby 50 ng of RNA are first converted to cDNA using 16 gene-specific primers. Using a set of training tissues, we developed a novel quantitative three-tiered algorithm that allows for accurate (overall accuracy = 61/63, 97%) discrimination of BE versus EA tissues using only three genes. The gene used in the first tier of the algorithm is TSPAN: samples not diagnosed as BE or EA by TSPAN in the first tier are then subjected to a second-tier analysis using ECGF1, followed by a third-tier analysis using SPARC. Addition of TFF1 and SBEM to the first tier (i.e., a five-gene marker panel) increases the overall accuracy of the assay to 98% (62/63) and results in mean molecular diagnostic scores (+/- SD) that are significantly different between EA and BE samples (3.19 +/- 1.07 versus -2.74 +/- 1.73, respectively). Our results suggest that relatively few genes can be used to monitor progression of BE to EA.

New Molecular Concepts of Barrett’s Esophagus: Clinical Implications and Biomarkers

Barrett's esophagus (BE) represents the most serious histological consequence of gastroesophageal reflux disease (GERD) that develops in 5-10% of patients with GERD. Given that BE is the only known precursor to esophageal adenocarcinoma (EA), a systematic endoscopic biopsy protocol can detect EAs at an early stage. However, endoscopic and histopathological evaluation of BE are not adequate for effective screening of high risk patients. Therefore, molecular abnormalities associated with BE have been considered as surrogate markers and their use as such is proposed. Flow cytometry is the most useful adjunct to histology, and ploidy status of BE is an independent risk factor. Cyclin D1 overexpression is inversely correlated with survival in EA. C-erbB2 (+) patients have poorer prognosis. High plasma adenomatous polyposis coli levels correlate with reduced patient survival. p53 expression allows patient risk for EA stratification. Nuclear factor-kappaB overexpression inversely correlates with good response to adjuvant chemotherapy and radiotherapy in EA. Patients with cyclooxygenase-2 overexpression have reduced survival rates. Increased E-cadherin staining is associated with shorter survival in EA patients who received chemoradiotherapy. Finally, existing data cannot rule out a correlation between EA and colorectal tumors. Seventeen BE molecular alterations yielded noteworthy clinical implications. Apart from endoscopy and histology, these data allow for better risk stratification for patients with BE and for more efficient and timely therapeutic approaches.

Barrett's oesophagus with predominant intestinal metaplasia correlates with superficial cyclo-oxygenase-2 expression, increased proliferation and reduced apoptosis: changes that are partially reversed by non-steroidal anti-inflammatory drugs usage

BACKGROUND

Cyclo-oxygenase-2 expression has been reported to play an important role in the metaplasia-dysplasia-carcinoma sequence in Barrett's oesophagus. However, the existence of cyclo-oxygenase-2 expressing cells in Barrett's epithelium is still uncertain.

AIM

To identify the cells that express cyclo-oxygenase-2 protein and to investigate the relationship between cyclo-oxygenase-2 expression and mucin-phenotype of Barrett's epithelium.

METHODS

Sections from 466 biopsy samples of Barrett's epithelium from 358 non-medicated patients were immunohistochemically examined for the cyclo-oxygenase-2 expression, mucin-phenotype, cell proliferation and apoptosis.

RESULTS

Cyclo-oxygenase-2 expression was detected in 71.0% of Barrett's epithelium biopsy samples. In Barrett's epithelium with the gastric predominant mucin-phenotype, cyclo-oxygenase-2 expression was mainly found in stromal and deep epithelial cells, whereas in intestinal predominant mucin-phenotype, it was mostly in superficial epithelial cell. A significant elevation of proliferating cell nuclear antigen index and suppression of apoptotic index was observed in Barrett's epithelium with superficial epithelial cyclo-oxygenase-2 expression. Neither such elevation of proliferating cell nuclear antigen index nor the suppression of apoptotic index could be found in chronic non-steroidal anti-inflammatory drugs users.

CONCLUSIONS

Barrett's epithelium with intestinal mucin and superficial epithelial cyclo-oxygenase-2 expression possess a higher proliferation potential, but this risk may be thwarted by non-steroidal anti-inflammatory drugs administration.

MUC1 and MUC2 in pancreatic neoplasia

MUCs are glycoproteins with various roles in homeostasis and carcinogenesis. Among other actions, MUC1 may inhibit cell-cell and cell-stroma interactions and function as a signal transducer, participating in cancer progression. In contrast, MUC2 is normally found only in goblet cells, where it contributes to the protective barrier function of these cells. Recently, a tumour suppressor role has been demonstrated for MUC2, and both MUC1 and MUC2 appear to have important roles in pancreatic neoplasia. MUC1 appears to be a marker of aggressive phenotype and may facilitate the vascular spread of carcinoma cells. In contrast, MUC2 is rarely detectable in aggressive pancreatic tumours, but is commonly expressed in intraductal papillary mucinous neoplasms (IPMNs), which are rare, indolent tumours, in intestinal IPMNs, and in indolent colloid carcinomas. MUC2 appears to be not only a marker of this indolent pathway, but also partly responsible for its less aggressive nature. Thus, in pancreatic neoplasia, MUC1 and MUC2 have potential diagnostic and prognostic value as markers of aggressive and indolent phenotypes, respectively, and have potential as therapeutic targets.

Trefoil factor family (TFF) peptides and cancer progression

TFF peptides are involved in mucosal maintenance and repair through motogenic and antiapoptotic activities. These peptides are overexpressed during inflammatory processes and cancer progression. They also function as scatter factors, proinvasive and angiogenic agents. Such a divergence is related to the pathophysiological state of tissues submitted to persistent aggressive situations during digestive processes in the normal gastrointestinal tract, inflammatory and neoplastic diseases. In agreement with this model, TFF peptides are connected with multiple oncogenic pathways. As a consequence, the TFF signaling pathways may serve as potential targets in the control of chronic inflammation and progression of human solid tumors.

TFF3 expression at the esophagogastric junction is increased in gastro-esophageal reflux disease (GERD)

At the gastric cardia, the molecular mechanisms of inflammation and metaplasia are incompletely understood. Thus, the aim of this study was to determine the expression of TFF1, TFF2 and TFF3 at this site and correlate these data with Helicobacter pylori infection or gastro-esophageal reflux disease (GERD). In 27 patients without intestinal metaplasia at the cardia, endoscopic biopsies were obtained for histology and RT-PCR. TFF1 and TFF2 were expressed in all cardia samples. TFF3 expression was significantly more frequent at the cardia (n = 15/24) than in the corpus (n = 2/26). TFF3 expression at the cardia was mainly observed in GERD patients, and there was a clear tendency towards higher interleukin-8 (IL-8) transcription levels; whereas TFF3 expression was not correlated with the H. pylori status or to tumor necrosis factor-alpha (TNF-alpha) expression. The expression of TFF3 at the cardia may represent an adaptation to GERD and precede the development of Barrett's esophagus.

Differentiation pathways in duodenal and ampullary carcinomas: a comparative study on mucin and trefoil peptide expression, including gastric and colon carcinomas

Duodenal carcinomas, such as ampullary tumors, may be a heterogeneous group of neoplasms that share differentiation features with gastric or colorectal carcinomas. Because of the cell- and tissue-specific expression patterns of mucins and trefoil peptides, these markers were used to investigate the differentiation status of duodenal and ampullary carcinomas in comparison with gastric and colorectal carcinomas. Adenocarcinomas (14 duodenal, 10 gastric, 11 ampullary and 10 colorectal) were examined immunohistochemically for the mucin gene products MUC1, MUC2, MUC5AC, MUC6 and the trefoil peptides TFF1 and TFF2. The tumors' expression profile for MUC5AC, MUC6 and TFF1 was used to distinguish between gastric- and intestinal-directed differentiation. The mucins that were most often expressed in the individual tumor types were MUC1 (duodenal and ampullary carcinomas), MUC2 (colorectal carcinomas) and MUC5AC (gastric carcinomas). Further classification focusing on the expression profile for MUC5AC, MUC6 and TFF1 revealed that 21% of the duodenal and 45% of the ampullary carcinomas demonstrated mainly gastric differentiation (positivity for all three markers or only two of them). The remaining duodenal and ampullary carcinomas showed nongastric, i.e., intestinal differentiation (all three markers negative or only one marker positive). The gastric differentiation pattern characterized 60% of gastric carcinomas. Colorectal carcinomas showed intestinal differentiation in 100% of cases. Duodenal carcinomas have a heterogeneous mucin expression pattern that is mainly related to either gastric differentiation or intestinal differentiation. This also holds for ampullary carcinomas. Among the markers used, MUC5AC, MUC6 and TFF1 are most useful for revealing differentiation pathways in duodenal and ampullary carcinoma.