Bile acids induce ectopic expression of intestinal guanylyl cyclase C Through nuclear factor-kappaB and Cdx2 in human esophageal cells

Efficacy of Linaclotide in Functional Dyspepsia and Constipation-Predominant Irritable Bowel Syndrome Overlap: A Randomized Trial

BACKGROUND AND AIM

Linaclotide is effective in relieving constipation-predominant irritable bowel syndrome symptoms. However, few studies focus on the efficacy of linaclotide for overlapping symptoms of functional dyspepsia among irritable bowel syndrome patients. This study aimed to assess the efficacy of linaclotide compared with lactulose in patients with functional dyspepsia and constipation-predominant irritable bowel syndrome overlap.

METHODS

Seventy-eight patient were randomized (2:1) to receive linaclotide 290 μg or lactulose 20 mL daily for 4 weeks. The primary endpoint was the overall treatment satisfaction for gastrointestinal symptom relief. The secondary endpoints included score changes in functional dyspepsia, constipation-predominant irritable bowel syndrome symptoms, and psychological status.

RESULTS

Seventy-one patients (47 with linaclotide and 24 with lactulose) completed the study. A higher proportion of patients receiving linaclotide reported partial or complete relief of gastrointestinal symptoms compared with patients receiving lactulose (87.2% vs. 54.2%, p = 0.002). Dyspeptic symptoms (postprandial fullness/early satiety and bloating) and bowel symptoms (stool frequency, consistency, straining, sensation of complete evacuation, and lower abdominal discomfort) showed greater improvement in linaclotide-treated patients than in lactulose group (p < 0.05).

CONCLUSIONS

Linaclotide shows better efficacy for functional dyspepsia and constipation-predominant irritable bowel syndrome overlap compared with lactulose.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05134584.

A review of potential mechanisms and treatments of gastric intestinal metaplasia

Gastric intestinal metaplasia (GIM) is a pathological process where gastric mucosal epithelial cells are replaced by intestinal-type cells, serving as a precursor lesion for gastric cancer. This transformation involves various genetic and environmental factors, affecting key genes and signaling pathways. Recent research has revealed complex mechanisms, including changes in gene expression, abnormal signaling pathway activation, and altered cell behavior. This review summarizes the latest research on GIM, discussing its pathogenesis, current treatment strategies, and potential efficacy of emerging approaches like gene editing, microbiome interventions, and integrative medicine. By exploring these strategies, we aim to provide more effective treatments for GIM and reduce gastric cancer incidence. The review also highlights the importance of interdisciplinary studies in understanding GIM mechanisms and improving treatment strategies.

CircJPH1 regulates the NF-κB/HERC5 axis to promote the malignant progression of esophageal squamous cell carcinoma through binding to XRCC6

Esophageal squamous cell carcinoma (ESCC) is a prevalent and malignant cancer with an unknown pathogenesis and a poor prognosis; therefore, the identification of effective biomarkers and targets is crucial for its diagnosis and treatment. Circular (circ)RNAs are prominent functional biomarkers and therapeutic targets in various diseases, particularly cancer, due to their widespread expression and regulatory mechanisms. Our study aimed to investigate the therapeutic potential of circRNA for ESCC. We identified Hsa_circ_0137111 for the first time as one of the most significantly up-regulated genes in ESCC sequencing and named it circJPH1. The results of the present study demonstrated an enhanced expression of circJPH1 in ESCC tissues. Moreover, circJPH1-knockdown could significantly inhibit the proliferation, migration, and invasion of ESCC cells, while its overexpression promoted these characteristics. In addition, circJPH1 promoted ESCC cell tumor growth in vivo. For the first time, mass spectrometry and RNA pull-down analysis revealed the interaction of X-ray repair cross-complementary 6 (XRCC6) protein with circJPH1, thereby promoting its nuclear translocation. Consequently, the nuclear factor kappa-B (NF-κB) signaling pathway was activated, leading to an up-regulation of HECT and RLD domain containing E3 ubiquitin protein ligase 5 (HERC5), thereby promoting ESCC progression. In summary, the present study elucidated the regulatory impact of circJPH1 on ESCC progression in vitro and in vivo, thereby indicating its potential role in ESCC treatment.

Gastric intestinal metaplasia: progress and remaining challenges

Most gastric cancers arise in the setting of chronic inflammation which alters gland organization, such that acid-pumping parietal cells are lost, and remaining cells undergo metaplastic change in differentiation patterns. From a basic science perspective, recent progress has been made in understanding how atrophy and initial pyloric metaplasia occur. However, pathologists and cancer biologists have long been focused on the development of intestinal metaplasia patterns in this setting. Arguably, much less progress has been made in understanding the mechanisms that lead to the intestinalization seen in chronic atrophic gastritis and pyloric metaplasia. One plausible explanation for this disparity lies in the notable absence of reliable and reproducible small animal models within the field, which would facilitate the investigation of the mechanisms underlying the development of gastric intestinal metaplasia (GIM). This review offers an in-depth exploration of the current state of research in GIM, shedding light on its pivotal role in tumorigenesis. We delve into the histological subtypes of GIM and explore their respective associations with tumor formation. We present the current repertoire of biomarkers utilized to delineate the origins and progression of GIM and provide a comprehensive survey of the available, albeit limited, mouse lines employed for modeling GIM and engage in a discussion regarding potential cell lineages that serve as the origins of GIM. Finally, we expound upon the myriad signaling pathways recognized for their activity in GIM and posit on their potential overlap and interactions that contribute to the ultimate manifestation of the disease phenotype. Through our exhaustive review of the progression from gastric disease to GIM, we aim to establish the groundwork for future research endeavors dedicated to elucidating the etiology of GIM and developing strategies for its prevention and treatment, considering its potential precancerous nature.

Receptor Guanylyl Cyclase C and Cyclic GMP in Health and Disease: Perspectives and Therapeutic Opportunities

Receptor Guanylyl Cyclase C (GC-C) was initially characterized as an important regulator of intestinal fluid and ion homeostasis. Recent findings demonstrate that GC-C is also causally linked to intestinal inflammation, dysbiosis, and tumorigenesis. These advances have been fueled in part by identifying mutations or changes in gene expression in GC-C or its ligands, that disrupt the delicate balance of intracellular cGMP levels and are associated with a wide range of clinical phenotypes. In this review, we highlight aspects of the current knowledge of the GC-C signaling pathway in homeostasis and disease, emphasizing recent advances in the field. The review summarizes extra gastrointestinal functions for GC-C signaling, such as appetite control, energy expenditure, visceral nociception, and behavioral processes. Recent research has expanded the homeostatic role of GC-C and implicated it in regulating the ion-microbiome-immune axis, which acts as a mechanistic driver in inflammatory bowel disease. The development of transgenic and knockout mouse models allowed for in-depth studies of GC-C and its relationship to whole-animal physiology. A deeper understanding of the various aspects of GC-C biology and their relationships with pathologies such as inflammatory bowel disease, colorectal cancer, and obesity can be leveraged to devise novel therapeutics.

The Role of CCN1 in Esophageal Adenocarcinoma: What We Have Learned From the Lab

Background: Esophageal cancer is one of the most common and deadliest cancers in the world, particularly esophageal adenocarcinoma. There has never been a special drug to treat it.Purpose: This article summarizes the work that we have done in our laboratory about the role of CCN1 in esophageal cancer and gives a new perspective of CCN1 biology.Research Design: This is a review article. Study Sample: The work was done using validated cell lines and fixed human tissue slides.Data Collection and Analysis: This is a review article, therefore, no data collection or analysis was involved.Results: CCN1 is a matricellular protein supporting adhesion, migration, and survival in normal cells, but in the esophageal cancer cells, it induces TRAIL-mediated apoptosis. CCN1 promotes TRAIL and its death receptor expression but downregulates the decoy receptors and survivin in a p53-dependant manner. It was thought that CCN1 relies on TNF to induce apoptosis, but our study found that these two molecules antagonize each other. CCN1 promotes TNFR1 cleavage and uses the soluble product to block TNF signaling, while TNF upregulates PGLYRP1 to overcome this obstacle because PGLYRP1 is a secreted protein that competes with TNF for TNFR1 binding. As a result, when CCN1 and TNF are present together in the vicinity of esophageal tumors, they cancel each other out.Conclusions: Based on our laboratory study, CCN1 has much potential to be a candidate for the treatment of esophageal cancer.

Tumor microenvironment characterization in esophageal cancer identifies prognostic relevant immune cell subtypes and gene signatures

Esophageal cancer (ESCA) is a common malignancy in the digestive system with a high mortality rate and poor prognosis. Tumor microenvironment (TME) plays an important role in the tumorigenesis, progression and therapy resistance of ESCA, whereas its role in predicting clinical outcomes has not been fully elucidated. In this study, we comprehensively estimated the TME infiltration patterns of 164 ESCA patients using Gene Set Variation Analysis (GSVA) and identified 4 key immune cells (natural killer T cell, immature B cell, natural killer cell, and type 1 T helper cell) associated with the prognosis of ESCA patients. Besides, two TME groups were defined based on the TME patterns with different clinical outcomes. According to the expression gene set between two TME groups, we built a model to calculate TMEscore based on the single-sample gene-set enrichment analysis (ssGSEA) algorithm. TMEscore systematically correlated the TME groups with genomic characteristics and clinicopathologic features. In conclusion, our data provide a novel TMEscore which can be regarded as a reliable index for predicting the clinical outcomes of ESCA.

Guanylyl cyclase 2C (GUCY2C) in gastrointestinal cancers: recent innovations and therapeutic potential

INTRODUCTION

Gastrointestinal (GI) cancers account for the second leading cause of cancer-related deaths in the United States. Guanylyl cyclase C (GUCY2C) is an intestinal signaling system that regulates intestinal fluid and electrolyte secretion as well as intestinal homeostasis. In recent years, it has emerged as a promising target for chemoprevention and therapy for GI malignancies.

AREAS COVERED

The loss of GUCY2C signaling early in colorectal tumorigenesis suggests it could have a significant impact on tumor initiation. Recent studies highlight the importance of GUCY2C signaling in preventing colorectal tumorigenesis using agents such as linaclotide, plecanatide, and sildenafil. Furthermore, GUCY2C is a novel target for immunotherapy and a diagnostic marker for primary and metastatic diseases.

EXPERT OPINION

There is an unmet need for prevention and therapy in GI cancers. In that context, GUCY2C is a promising target for prevention, although the precise mechanisms by which GUCY2C signaling affects tumorigenesis remain to be defined. Furthermore, clinical trials are exploring its role as an immunotherapeutic target for vaccines to prevent metastatic disease. Indeed, GUCY2C is an emerging target across the disease continuum from chemoprevention, to diagnostic management, through the treatment and prevention of metastatic diseases.

GUCY2C as a biomarker to target precision therapies for patients with colorectal cancer

Introduction

Colorectal cancer (CRC) is one of the most-deadly malignancies worldwide. Current therapeutic regimens for CRC patients are relatively generic, based primarily on disease type and stage, with little variation. As the field of molecular oncology advances, so too must therapeutic management of CRC. Understanding molecular heterogeneity has led to a new-found promotion for precision therapy in CRC; underlining the diversity of molecularly targeted therapies based on individual tumor characteristics.

Areas covered

We review current approaches for the treatment of CRC and discuss the potential of precision therapy in advanced CRC. We highlight the utility of the intestinal protein guanylyl cyclase C (GUCY2C), as a multi-purpose biomarker and unique therapeutic target in CRC. Here, we summarize current GUCY2C-targeted approaches for treatment of CRC.

Expert opinion

The GUCY2C biomarker has multi-faceted utility in medicine. Developmental investment of GUCY2C as a diagnostic and therapeutic biomarker offers a variety of options taking the molecular characteristics of cancer into account. From GUCY2C-targeted therapies, namely cancer vaccines, CAR-T cells, and monoclonal antibodies, to GUCY2C agonists for chemoprevention in those who are at high risk for developing colorectal cancer, the utility of this protein provides many avenues for exploration with significance in the field of precision medicine.

HDAC6/HNF4α loop mediated by miR-1 promotes bile acids-induced gastric intestinal metaplasia

BACKGROUND

Gastric intestinal metaplasia (IM) is considered a precancerous lesion, and bile acids (BA) play a critical role in the induction of IM. Ectopic expression of HNF4α was observed in a BA-induced IM cell model. However, the mechanisms underlying the upregulation of the protein in IM cells remains to be elucidated.

METHODS

The effects of HNF4α on gastric mucosal cells in vivo were identified by a transgenic mouse model and RNA-seq was used to screen downstream targets of deoxycholic acid (DCA). The expression of pivotal molecules and miR-1 was detected by immunohistochemistry and in situ hybridization in normal, gastritis and IM tissue slides or microarrays. The transcriptional regulation of HDAC6 was investigated by chromatin immunoprecipitation (ChIP) and luciferase reporter assays.

RESULTS

The transgenic mouse model validated that HNF4α stimulated the HDAC6 expression and mucin secretion in gastric mucosa. Increased HDAC6 and HNF4α expression was also detected in the gastric IM cell model and patient specimens. HNF4α could bind to and activate HDAC6 promoter. In turn, HDAC6 enhanced the HNF4α protein level in GES-1 cells. Furthermore, miR-1 suppressed the expression of downstream intestinal markers by targeting HDAC6 and HNF4α.

CONCLUSIONS

Our findings show that the HDAC6/HNF4α loop regulated by miR-1 plays a critical role in gastric IM. Blocking the activation of this loop could be a potential approach to preventing BA-induced gastric IM or even gastric cancer (GC).

Mechanical characterization of bio composite films as a novel drug carrier platform for sustained release of 5-fluorouracil for colon cancer: Methodological investigation

In this study, we employed Pectin (PC) as a matrix that is hybridized with three different nucleobase (NB) units (cytosine, thymine, uracil) to generate pectin-nucleobase(PC-NB) biocomposite films stabilized through bio-multiple hydrogen bonds (BMHBs) as drug carrier for anticancer 5-Fluorouracil (5-FU). Prepared biocomposite films were characterized by Fourier Transform Infra-red Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimmetry Analysis (TGA) and Scanning Electron Microscope (SEM). Mechanical and sorption properties were also evaluated. In vitro drug release performed in both acidic pH 1.2 (stomach pH) and alkaline pH 7.4 (intestinal pH) showed that incorporation of nucleobases into pectin significantly restricted release rate of 5-FU particularly under acidic condition (pH 1.2). Hemolysis assays demonstrated that PC-NB-5-FU biocomposite film drug carriers were hemocompatible. Confocal microscope analysis indicates facilitated cellular uptake of PC-NB-5-FU film in HT-29 colon cancer cell line, which in turn result in a higher potential of apoptosis. Confocal imaging of fluorescent live/dead cell indicators and MTT assay outcomes, both demonstrated significant decreases in cellular viability of PC-NB-5-FU biocomposite films. Collectively, our findings indicate that this PC-NB-5-FU biocomposite films can be conferred as a proficient formulation for targeted delivery of colon cancer drugs.

Molecular Dynamics in Esophageal Adenocarcinoma: Who's in Control?

Esophageal adenocarcinoma (EAC) is one of the fastest-growing cancers in the world. It occurs primarily due to the chronic gastroesophageal reflux disease (GERD), during which the esophageal epithelium is frequently exposed to the acidic fluid coming up from the stomach. This triggers gene mutations in the esophageal cells, which may lead to EAC development. While p53 is activated to get rid of the mutated cells, NFκB orchestrates the remaining cells to heal the wound. However, if the mutations happen to TP53 (a common occasion), the mutant product turns to support tumorigenesis. In this case, NFκB goes along with the mutant p53 to facilitate cancer progression. TRAIL is one of the cytokines produced in response to GERD episodes and it can kill cancer cells selectively, but its clinical use has not been as successful as expected, because some highly sophisticated defense mechanisms against TRAIL have developed during the malignancy. To clear the obstacles for TRAIL action, using a second agent to disarm the cancer cells is required. CCN1 appears to be such a molecule. While supporting normal esophageal cell growth, CCN1 suppresses malignant transformation by inhibiting NFκB and kills the EAC cell through TRAIL-mediated apoptosis.

Role of Kruppel-Like Factor 5 in Deoxycholic Acid-Mediated Intestinal Transdifferentiation of Esophageal Squamous Epithelium

Barrett's esophagus (BE) is an acquired condition in which normal squamous epithelium is replaced with metaplastic columnar epithelium as a consequence of gastroesophageal reflux disease. BE is known as a precursor of esophageal adenocarcinoma. Currently, the molecular mechanism underlying epithelial metaplasia in BE patients remains unknown. Therefore, we investigated the role of Krüppel-like factor 5 (KLF5) signaling in the initiation of BE-associated metaplasia. Sprague-Dawley (SD) rats were used to create a surgical model of bile reflux injury. Immunohistochemistry was performed to analyze human and mouse esophageal specimens. Human esophageal squamous epithelial (HET-1A) cells were treated with bile acid and used in transfection experiments. Quantitative real-time PCR and western blot analysis were performed to detect the expression of KLF5, CDX2, MUC2 and villin. Epithelial tissue from both the rat BE model and human BE patients strongly expressed KLF5, CDX2, MUC2, and villin. Bile acid treatment also increased the expression of KLF5, CDX2, MUC2 and villin in esophageal epithelial cells in a time-dependent manner. Moreover, siRNA-mediated knockdown of KLF5 blocked the expression of CDX2, MUC2 and villin, but transfection of a KLF5 expression vector into esophageal epithelial cells promoted their transdifferentiation into columnar-like cells, as demonstrated by increased expression of the intestinal markers CDX2, MUC2 and villin. Thus, in addition to its function as a transcription factor, KLF5 may be linked to an increased risk of BE development.

Barretts's carcinogenesis

Barrett's esophagus is considered a precancerous lesion of esophageal adenocarcinoma (EAC). Long‐segment Barrett's esophagus, which is generally associated with intestinal metaplasia, has a higher rate of carcinogenesis than short‐segment Barrett's esophagus, which is mainly composed of cardiac‐type mucosa. However, a large number of cases reportedly develop EAC from the cardiac‐type mucosa which has the potential to involve intestinal phenotypes. There is no consensus regarding whether the definition of Barrett's epithelium should include intestinal metaplasia. Basic researches using rodent models have provided information regarding the origins of Barrett's epithelium. Nevertheless, it remains unclear whether differentiated gastric columnar epithelium or stratified esophageal squamous epithelium undergo transdifferentiation into the intestinal‐type columnar epithelium, transcommittment into the columnar epithelium, or whether the other pathways exist. Reflux of duodenal fluid including bile acids into the stomach may occur when an individual lies down after eating, which could cause the digestive juices to collect in the fornix of the stomach. N‐nitroso‐bile acids are produced with nitrites that are secreted from the salivary glands, and bile acids can drive expression of pro‐inflammatory cytokines via EGFR or the NF‐κB pathway. These steps may contribute significantly to carcinogenesis.

SOX2 interferes with the function of CDX2 in bile acid-induced gastric intestinal metaplasia

Background

Intestinal metaplasia (IM) is a premalignant lesion associated with gastric cancer. Both animal and clinical studies have revealed that bile acid reflux and subsequent chronic inflammation are key causal factors of IM. Previous studies indicated that SOX2, the key transcription factor in gastric differentiation, was downregulated during IM development while CDX2, the pivotal intestine-specific transcription factor was upregulated significantly. However, it remains unclear whether the downregulation of SOX2 promotes gastric IM emergence or is merely a concomitant phenomenon. In addition, the underlying mechanisms of SOX2 downregulation during IM development are unclear.

Methods

Gastric cell lines were treated with deoxycholic acid (DCA) in a dose-dependent manner. The expression of CDX2 and miR-21 in gastric tissue microarray were detected by immunohistochemistry and in situ hybridization. Coimmunoprecipitation and immunofluorescence were performed to ascertain the interaction of SOX2 and CDX2. Luciferase reporter assays were used to detect the transcriptional activity of CDX2, and confirm miR-21 binding to SOX2 3′-UTR. The protein level of SOX2, CDX2 and downstream IM-specific genes were investigated using western blotting. mRNA level of miR-21, SOX2, CDX2 and downstream IM-specific genes were detected by qRT-PCR.

Results

Bile acid treatment could suppress SOX2 expression and simultaneously induce expression of CDX2 in gastric cell lines. Furthermore, we demonstrated that SOX2 overexpression could significantly inhibit bile acid- and exogenous CDX2-induced IM-specific gene expression, including KLF4, cadherin 17 and HNF4α expression. In contrast, SOX2 knockdown had the opposite effect. A dual-luciferase reporter assay demonstrated that SOX2 overexpression could significantly suppress CDX2 transcriptional activity in HEK293T cells. CDX2 and SOX2 could form protein complexes in the nucleus. In addition, bile acid induced the expression of miR-21. The inhibition of SOX2 in bile acid-treated gastric cell lines was rescued by miR-21 knockdown.

Conclusions

These findings suggested that SOX2 can interfere with the transcriptional activity of CDX2 in bile acid-induced IM and that miR-21 might play a key role in this process, which shed new lights in the prevention of gastric cancer.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0739-8) contains supplementary material, which is available to authorized users.

Bile acids promote gastric intestinal metaplasia by upregulating CDX2 and MUC2 expression via the FXR/NF-κB signalling pathway

Bile acids serve a critical role in the induction of gastric intestinal metaplasia (IM) and gastric carcinogenesis. The present study investigated the effects of bile acids on the induction of gastric IM formation. The results demonstrated that the expression levels of caudal-related homeobox transcription factor 2 (CDX2), mucin 2 (MUC2) and farnesoid X receptor (FXR) were increased in vitro and in vivo following treatment with bile acids, and CDX2 transcriptionally activated MUC2 expression. Furthermore, knockdown of FXR attenuated bile acid-enhanced CDX2 promoter activity and protein expression. Conversely, the FXR agonist GW4064 synergistically enhanced bile acid-induced CDX2 promoter activity. Bile acid treatment led to an increase in nuclear factor (NF)-κB activity and protein expression. Treatment with GW4064 or the FXR antagonist Z-guggulsterone enhanced or attenuated bile acid-induced NF-κB activity, respectively. In addition, quantitative chromatin immunoprecipitation confirmed that bile acids led to enhanced binding of p50 to the CDX2 promoter, whereas this effect was not observed for p65. Treatment with GW4064 or Z-guggulsterone enhanced and attenuated the binding activity of p50 to the CDX2 promoter, respectively. These results indicated that bile acids may activate the FXR/NF-κB signalling pathway, thereby upregulating CDX2 and MUC2 expression in normal gastric epithelial cells.

Guts and Gall: Bile Acids in Regulation of Intestinal Epithelial Function in Health and Disease

Epithelial cells line the entire surface of the gastrointestinal tract and its accessory organs where they primarily function in transporting digestive enzymes, nutrients, electrolytes, and fluid to and from the luminal contents. At the same time, epithelial cells are responsible for forming a physical and biochemical barrier that prevents the entry into the body of harmful agents, such as bacteria and their toxins. Dysregulation of epithelial transport and barrier function is associated with the pathogenesis of a number of conditions throughout the intestine, such as inflammatory bowel disease, chronic diarrhea, pancreatitis, reflux esophagitis, and cancer. Driven by discovery of specific receptors on intestinal epithelial cells, new insights into mechanisms that control their synthesis and enterohepatic circulation, and a growing appreciation of their roles as bioactive bacterial metabolites, bile acids are currently receiving a great deal of interest as critical regulators of epithelial function in health and disease. This review aims to summarize recent advances in this field and to highlight how bile acids are now emerging as exciting new targets for disease intervention.

hTERT promotes gastric intestinal metaplasia by upregulating CDX2 via NF-κB signaling pathway

Background

hTERT has been reported involved in the proliferation and metastasis of gastric cancer, but the role of hTERT in gastric intestinal metaplasia, a premalignant lesion of the gastric mucosa was unknown. The aim of the present study was to investigate the role of hTERT in GIM and the effect of hTERT on CDX2 expression in gastric cells.

Results

Experiments showed that expression of hTERT was significantly higher in GIM than in normal gastric mucosa. Moreover, hTERT increased the KLF4 level via NF-κB during GIM. Furthermore, KLF4 is involved in the up-regulation of CDX2 induced by hTERT, and hTERT can interact with p50, thereby increasing the level of CDX2.

Materials and Methods

Immunohistochemistry was used to detect the expression of hTERT in gastric intestinal metaplasia tissue. Then, effect of hTERT on the expression of CDX2 was detected by qRT-PCR, WB and dual luciferase experiment. The role of p65 and p50 in the regulation of CDX2 were further detected by WB, CO-IP and ChIP.

Conclusions

We may conclude that hTERT promotes GIM by up-regulating CDX2 via NF-κB signaling pathway.

Consistent expression of guanylyl cyclase-C in primary and metastatic gastrointestinal cancers

BACKGROUND

The transmembrane receptor guanylate cyclase-C (GCC) has been found to be expressed in colorectal cancers. However, limited data are available on GCC protein expression in non-colorectal gastrointestinal tumors and few studies have reported whether GCC protein expression was consistently preserved in synchronous primary and metastatic cancer tissues.

METHODS

GCC protein status was assessed by immunohistochemistry in tumor specimens from individuals (n = 627) with gastrointestinal tumors, including esophageal (n = 130), gastric (n = 276), pancreatic (n = 136), and colorectal (n = 85) primary and metastatic tumors. Tissue specimens consisted of tissue microarrays containing esophageal, gastric, pancreatic tumors, and whole-slide tissue sections from colorectal cancer patients with matching primary and metastatic tumors.

RESULT

Among the evaluated esophageal, gastric, and pancreatic tumors, the frequency of GCC positivity at the protein level ranged from 59% to 68%. GCC was consistently expressed in primary and matched/synchronous metastatic lesions of colorectal cancer tissues derived from the same patients.

CONCLUSION

This observational study demonstrated the protein expression of GCC across various gastrointestinal malignancies. In all cancer histotypes, GCC protein localization was observed predominantly in the cytoplasm compared to the membrane region of tumor cells. Consistent immunohistochemistry detection of GCC protein expression in primary colorectal cancers and in their matched liver metastases suggests that the expression of GCC is maintained throughout the process of tumor progression and formation of metastatic disease.

Acidified bile acids enhance tumor progression and telomerase activity of gastric cancer in mice dependent on c-Myc expression

c-Myc overexpression has been implicated in several malignancies including gastric cancer. Here, we report that acidified bile acids enhance tumor progression and telomerase activity in gastric cancer via c-Myc activation both in vivo and in vitro. c-Myc mRNA and protein levels were assessed in ten primary and five local recurrent gastric cancer samples by quantitative real-time polymerase chain reaction and western blotting analysis. The gastric cancer cell line MGC803 was exposed to bile salts (100 μmol/L glycochenodeoxycholic acid and deoxycholic acid) in an acid medium (pH 5.5) for 10 min daily for 60 weeks to develop an MGC803-resistant cell line. Control MGC803 cells were grown without acids or bile salts for 60 weeks as a control. Cell morphology, proliferation, colony formation and apoptosis of MGC803-resistant cells were analyzed after 60 weeks. To determine the involvement of c-Myc in tumor progression and telomere aging in MGC803-resistant cells, we generated xenografts in nude mice and measured xenograft volume and in vivo telomerase activity. The c-Myc and hTERT protein and mRNA levels were significantly higher in local recurrent gastric cancer samples than in primary gastric cancer samples. MGC803-resistant cells showed a marked phenotypic change under normal growth conditions with more clusters and acini, and exhibited increased cell viability and colony formation and decreased apoptosis in vitro. These phenotypic changes were found to be dependent on c-Myc activation using the c-Myc inhibitor 10058-F4. MGC803-resistant cells also showed a c-Myc-dependent increase in xenograft growth and telomerase activity in vivo. In conclusion, these observations support the hypothesis that acidified bile acids enhance tumor progression and telomerase activity in gastric cancer and that these effects are dependent on c-Myc activity. These findings suggest that acidified bile acids play an important role in the malignant progression of local recurrent gastric cancer.

Antibody-drug conjugate directed against the guanylyl cyclase antigen for the treatment of gastrointestinal malignancies

Antibody-directed cancer chemotherapy in the form of antibody-drug conjugates (ADCs) may improve the therapeutic index with the potential to enhance efficacy and decrease systemic toxicity. ADCs consist of three key components including an antibody that specifically binds to the target, a toxic agent and a linker which releases the toxic agent inside tumor cells. A novel ADC, MLN0264 (TAK-264) was recently investigated in patients with gastrointestinal (GI) malignancies. TAK-264 is an anti- guanylyl cyclase C (GCC) antibody conjugated via a protease-cleavable linker to the potent anti-microtubule agent monomethyl auristatin E (MMAE) (linker and toxin licensed from Seattle Genetics). Following binding to GCC, the ADC is internalized and transported to lysosomes where MMAE is released to bind to tubulin, leading to cell cycle arrest and apoptosis. This GCC targeting ADC has been evaluated in clinical studies in patients with advanced gastrointestinal malignancies. The early findings from Phase 1 study have shown preliminary activity signals in gastric, gastroesophageal, and pancreatic cancer. Results from two phase II studies in pancreatic and gastoesophageal adenocarcinoma showed only limited activity. Antibody-drug-conjugates offer a promising therapeutic modality aimed at providing target-directed cancer chemotherapy. Herein we discuss the GCC target and gastrointestinal malignancies where GCC based targeted therapies could further evolve and offer a significant clinical benefit.

Survivin activates NF‑κB p65 via the IKKβ promoter in esophageal squamous cell carcinoma

Survivin and transcription factor p65 (NF‑κB p65) participate in the progression of esophageal squamous cell carcinoma (ESCC). However, the mechanism of NF‑κB p65 activation in ESCC remains to be elucidated. The aim of the present study was to investigate the role of survivin in the activation of NF‑κB p65 in ESCC. The expression levels of survivin, NF‑κB p65, inhibitor of nuclear factor κB kinase subunit α (IKKα) and inhibitor of nuclear factor κB kinase subunit β (IKKβ) were detected in ESCC tissue samples. Eca109 and KYSE150 cells were cultured and survivin activity was modulated via transfection with an overexpression plasmid, a small hairpin RNA plasmid and a specific inhibitor. Quantitative reverse transcription-polymerase chain reaction and western blotting assays were conducted to assess the effects of survivin on the expression levels of IKKα, IKKβ and NF‑κB p65. Cell cycle and apoptosis assays were conducted to detect surviving-dependent cellular behavior changes. In addition, the luciferase reporter gene assay and chromatin immunoprecipitation assay were conducted to determine the genomic sites responsible for surviving-induced activation of NF‑κB p65. The present study demonstrated that the expression of survivin is positively correlated with IKKα and IKKβ in ESCC tissues. Survivin affected the mRNA and protein expression levels of IKKα, IKKβ, and NF‑κB p65 in Eca109 and KYSE150 cells. Furthermore, survivin increased the transcriptional activity of the IKKβ promoter and bound to the IKKβ promoter region in the Eca109 cells. Downregulation of survivin arrested the cell cycle at the G2/M phase and induced apoptosis. Results of the present study suggest that survivin activates NF‑κB p65 in Eca109 cells via binding to the IKKβ promoter region and upregulating IKKβ promoter transcriptional activity. Survivin overexpression activates NF‑κB p65, which is important in the acquisition and maintenance of the oncogenic characteristics of ESCC.

Immature myeloid progenitors promote disease progression in a mouse model of Barrett's-like metaplasia

Cdx2, an intestine specific transcription factor, is expressed in Barrett's esophagus (BE). We sought to determine if esophageal Cdx2 expression would accelerate the onset of metaplasia in the L2-IL-1β transgenic mouse model for Barrett's-like metaplasia. The K14-Cdx2::L2-IL-1β double transgenic mice had half as many metaplastic nodules as control L2-IL-1β mice. This effect was not due to a reduction in esophageal IL-1β mRNA levels nor diminished systemic inflammation. The diminished metaplasia was due to an increase in apoptosis in the K14-Cdx2::L2-IL-1β mice. Fluorescence activated cell sorting of immune cells infiltrating the metaplasia identified a population of CD11b+Gr-1+ cells that are significantly reduced in K14-Cdx2::L2-IL-1β mice. These cells have features of immature granulocytes and have immune-suppressing capacity. We demonstrate that the apoptosis in K14-Cdx2::L2-IL-1β mice is CD8+ T cell dependent, which CD11b+Gr-1+ cells are known to inhibit. Lastly, we show that key regulators of CD11b+Gr-1+ cell development, IL-17 and S100A9, are significantly diminished in the esophagus of K14-Cdx2::L2-IL-1β double transgenic mice. We conclude that metaplasia development in this mouse model for Barrett's-like metaplasia requires suppression of CD8+ cell dependent apoptosis, likely mediated by immune-suppressing CD11b+Gr-1+ immature myeloid cells.

Farnesoid X receptor signal is involved in deoxycholic acid-induced intestinal metaplasia of normal human gastric epithelial cells

The farnesoid X receptor (FXR) signaling pathway is known to be involved in the metabolism of bile acid, glucose and lipid. In the present study, we demonstrated that 400 µmol/l deoxycholic acid (DCA) stimulation promotes the proliferation of normal human gastric epithelial cells (GES-1). In addition, DCA activated FXR and increased the expression of intestinal metaplasia genes, including caudal-related homeobox transcription factor 2 (Cdx2) and mucin 2 (MUC2). The treatment of FXR agonist GW4064/antagonist guggulsterone (Gug.) significantly increased/decreased the expression levels of FXR, Cdx2 and MUC2 protein in DCA-induced GES-1 cells. GW4064/Gug. also enhanced/reduced the nuclear factor-κB (NF-κB) activity and binding of the Cdx2 promoter region and NF-κB, the most common subunit p50 protein. Taken together, the results indicated that DCA is capable of modulating the expression of Cdx2 and the downstream MUC2 via the nuclear receptor FXR-NF-κB activity in normal gastric epithelial cells. FXR signaling pathway may therefore be involved in the intestinal metaplasia of human gastric mucosa.

Risk factors affecting the Barrett's metaplasia-dysplasia-neoplasia sequence

Esophageal adenocarcinoma has the fastest growing incidence rate of any cancer in the United States, and currently carries a very poor prognosis with 5 years relative survival rates of less than 15%. Current curative treatment options are limited to esophagectomy, a procedure that suffers from high complication rates and high mortality rates. Metaplasia of the esophageal epithelium, a condition known as Barrett’s esophagus (BE), is widely accepted as the precursor lesion for adenocarcinoma of the esophagus. Recently, radio-frequency ablation has been shown to be an effective method to treat BE, although there is disagreement as to whether radio-frequency ablation should be used to treat all patients with BE or whether treatment should be reserved for those at high risk for progressing to esophageal adenocarcinoma while continuing to endoscopically survey those with low risk. Recent research has been targeted towards identifying those at greater risk for progression to esophageal adenocarcinoma so that radio-frequency ablation therapy can be used in a more targeted manner, decreasing the total health care cost as well as improving patient outcomes. This review discusses the current state of the literature regarding risk factors for progression from BE through dysplasia to esophageal adenocarcinoma, as well as the current need for an integrated scoring tool or risk stratification system capable of differentiating those patients at highest risk of progression in order to target these endoluminal therapies.

Modification of Helicobacter pylori Peptidoglycan Enhances NOD1 Activation and Promotes Cancer of the Stomach

Helicobacter pylori (H. pylori) is the strongest known risk factor for gastric carcinogenesis. One cancer-linked locus is the cag pathogenicity island, which translocates components of peptidoglycan into host cells. NOD1 is an intracellular immune receptor that senses peptidoglycan from Gram-negative bacteria and responds by inducing autophagy and activating NF-κB, leading to inflammation-mediated bacterial clearance; however chronic pathogens can evade NOD1-mediated clearance by altering peptidoglycan structure. We previously demonstrated that the H. pylori cag(+) strain 7.13 rapidly induces gastric cancer in Mongolian gerbils. Using 2D-DIGE and mass spectrometry, we identified a novel mutation within the gene encoding the peptidoglycan deacetylase PgdA; therefore, we sought to define the role of H. pylori PgdA in NOD1-dependent activation of NF-κB, inflammation, and cancer. Coculture of H. pylori strain 7.13 or its pgdA(-) isogenic mutant with AGS gastric epithelial cells or HEK293 epithelial cells expressing a NF-κB reporter revealed that pgdA inactivation significantly decreased NOD1-dependent NF-κB activation and autophagy. Infection of Mongolian gerbils with an H. pylori pgdA(-) mutant strain led to significantly decreased levels of inflammation and malignant lesions in the stomach; however, preactivation of NOD1 before bacterial challenge reciprocally suppressed inflammation and cancer in response to wild-type H. pylori. Expression of NOD1 differs in human gastric cancer specimens compared with noncancer samples harvested from the same patients. These results indicate that peptidoglycan deacetylation plays an important role in modulating host inflammatory responses to H. pylori, allowing the bacteria to persist and induce carcinogenic consequences in the gastric niche.

Guggulsterone, a plant-derived inhibitor of NF-TB, suppresses CDX2 and COX-2 expression and reduces the viability of esophageal adenocarcinoma cells

BACKGROUND/AIMS

Induction by bile acid of caudal type homeobox 2 (CDX2) and cyclooxygenase-2 (COX-2) expression via nuclear factor-κB (NF-κB) activation is a critical event in the development of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). Guggulsterone (GS) is a plant sterol that inhibits NF-κB activity. Here, we evaluated whether GS has either or both chemopreventive or therapeutic effects against EAC.

METHODS

Two EAC cells lines were treated with deoxycholic acid (DCA) in the presence of GS or vehicle. The levels of transcription and translation of IκBα, CDX2, and COX-2 were determined. Prostaglandin E2 (PGE2) levels, cell viability, and cell cycle distribution were assessed as well.

RESULTS

GS inhibited DCA-induced IκBα phosphorylation. GS and the NF-κB inhibitor BAY11-7085 suppressed DCA-induced CDX2 and COX-2 expression in EAC cells. GS also suppressed basal transcription levels of CDX2 and COX-2 and reduced constitutive synthesis of COX-2 and PGE2. Further, GS reduced the viability of EAC cells, increased their numbers in the apoptotic sub-G1 fraction.

CONCLUSION

GS suppressed DCA-induced and NF-κB-dependent activation of CDX2 and COX-2 expression. Further, GS also reduced the viability of EAC cells. GS may serve as candidate for preventing and treating EAC and BE.

Pharmacologic treatments for esophageal disorders

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on the role for ketamine and other alternative treatments in esophageal disorders; the use of linaclotide in the treatment of esophageal pain; the alginate test as a diagnostic criterion in gastroesophageal reflux disease (GERD); the use of baclofen in treatment of GERD; the effects of opioids on the esophagus; the use of antagonists on the receptor level in GERD; the effect of local formulation of drugs on the esophageal mucosa; and the use of electroencephalographic fingerprints to predict the effect of pharmacological treatment.

Upregulation of miRNA-143, -145, -192, and -194 in esophageal epithelial cells upon acidic bile salt stimulation

Barrett's esophagus (BE) is a metaplastic condition of the distal esophagus that occurs because of chronic gastroesophageal reflux. Previous studies have identified BE-specific microRNAs (miRNAs) in comparison with normal squamous epithelium (SQ). We hypothesized that BE-specific miRNAs could be induced in esophageal SQ cells by exposure to acid and/or bile salts. We aimed to determine whether BE-specific miRNAs are upregulated in an esophageal SQ cell line (Het-1A) in an environment with acid and/or bile salts and whether this is nuclear factor-κB (NF-κB) dependent. Acid and/or bile salt incubations were performed in Het-1A cells. Experiments were performed with or without inhibiting the NF-κB pathway. Quantitative reverse transcriptase polymerase chain reaction was performed to determine expression of miRNA-143, -145, -192, -194, cyclo-oxygenase-2 (COX2), mucin 2 (MUC2), and sex determining region Y-box 9. For validation, we determined levels of these miRNAs in biopsies from patients with reflux esophagitis and normal SQ. Significantly increased expression levels of miRNA-143 (2.7-fold), -145 (2.6-fold), -192 (2.0-fold), -194 (2.2-fold), COX2, MUC2, and sex determining region Y-box 9 were found upon acidic bile salt incubation, but not upon acid or bile salt alone. NF-κB pathway inhibition significantly decreased miRNA-143, -192, -194, COX2, and MUC2 expression. Additionally, miRNA-143, -145 and -194 expression was increased in reflux esophagitis biopsies compared with normal SQ, but no changes were found in miRNA-192 expression. Our findings suggest that upregulation of BE-specific miRNAs by acidic bile may be an early event in the transition of SQ to BE and that their expression is partly regulated by the NF-κB pathway.

Chemoprevention of esophageal adenocarcinoma in a rat model by ursodeoxycholic acid

Reflux of bile acid into the esophagus induces esophagitis, inflammation-stimulated hyperplasia, metaplasia such as Barrett's esophagus (BE), and esophageal adenocarcinoma (EAC). Caudal-type homeobox 2 (Cdx2) via nuclear factor (NF)-κB induced by bile acid is an important factor in the development of BE and EAC. In colorectal cancer, experimental data suggest a chemopreventive effect of ursodeoxycholic acid (UDCA). We hypothesized that UDCA may protect against the esophageal inflammation-metaplasia-carcinoma sequence by decreasing the overall proportion of the toxic bile acids. Wistar male rats that underwent a duodenoesophageal reflux procedure were divided into two groups. One group was given commercial chow (control group), and the other was given experimental chow containing UDCA (UDCA group). The animals were killed at 40 weeks after surgery, and their bile and esophagus were examined. In the UDCA group, the esophagitis was milder and the incidence of BE was significantly lower (p < 0.05) than in the control group, and EAC was not observed (p < 0.05). In analysis of the compartment of bile acid, UDCA was markedly increased in the UDCA group compared with the control group (32.7 ± 11.4 vs. 0.82 ± 0.33 mmol/L, p < 0.05) and cholic acid was decreased (32.7 ± 4.05 vs. 60.9 ± 8.26 mmol/L, p < 0.05). Expression intensity of Cdx2 and NF-κB was greater in the control group than in the UDCA group (p < 0.05). UDCA may be a chemopreventive agent against EAC by varying the bile acid composition.

Glutathione Peroxidase 7 Suppresses Bile Salt-Induced Expression of Pro-Inflammatory Cytokines in Barrett's Carcinogenesis

Esophageal adenocarcinoma (EAC) is the most frequent malignancy in the esophagus in the US and its incidence has been rising rapidly in the past few decades. Chronic gastroesophageal reflux disease (GERD), where the esophageal epithelium is abnormally exposed to acid and bile salts, is a pro-inflammatory condition that is the main risk factor for the development of Barrett's esophagus (BE) and its progression to EAC. Glutathione peroxidase 7 (GPX7) is frequently silenced through DNA hypermethylation during Barrett's tumorigenesis. In this study, we investigated the role of GPX7 in regulating the bile salts-induced inflammatory signaling in Barrett's carcinogenesis. Using quantitative real-time PCR (qRT-PCR), we demonstrated a significant induction in the expression levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-8) and chemokines (CXCL-1 and CXCL-2) in esophageal cells after exposure to acidic (pH4) or neutral (pH7) bile salts. Western blot analysis showed that exposure to acidic and neutral bile salts increased p-NF-κB-p65 (S536) protein levels independent of ROS. Reconstitution of GPX7 expression in EAC cells abolished the increase of p-p65 (S536) protein levels and mRNA expression of cytokines and chemokines upon treatment with acidic and neutral bile salts. Examination of human primary EAC tissues by qRT-PCR demonstrated significant overexpression of cytokines (TNF-α, IL-1β and IL-8) in EAC samples, as compared to normal samples, with significant inverse correlation with GPX7 expression level. Taken together, the loss of GPX7 expression promotes bile salt-induced activation of pro-inflammatory cytokines and chemokines; important contributors to GERD-associated Barrett's carcinogenesis.

Pulsatile exposure to simulated reflux leads to changes in gene expression in a 3D model of oesophageal mucosa

Oesophageal exposure to duodenogastroesophageal refluxate is implicated in the development of Barrett's metaplasia (BM), with increased risk of progression to oesophageal adenocarcinoma. The literature proposes that reflux exposure activates NF-κB, driving the aberrant expression of intestine-specific caudal-related homeobox (CDX) genes. However, early events in the pathogenesis of BM from normal epithelium are poorly understood. To investigate this, our study subjected a 3D model of the normal human oesophageal mucosa to repeated, pulsatile exposure to specific bile components and examined changes in gene expression. Initial 2D experiments with a range of bile salts observed that taurochenodeoxycholate (TCDC) impacted upon NF-κB activation without causing cell death. Informed by this, the 3D oesophageal model was repeatedly exposed to TCDC in the presence and absence of acid, and the epithelial cells underwent gene expression profiling. We identified ~300 differentially expressed genes following each treatment, with a large and significant overlap between treatments. Enrichment analysis (Broad GSEA, DAVID and Metacore™; GeneGo Inc) identified multiple gene sets related to cell signalling, inflammation, proliferation, differentiation and cell adhesion. Specifically NF-κB activation, Wnt signalling, cell adhesion and targets for the transcription factors PTF1A and HNF4α were highlighted. Our data suggest that HNF4α isoform switching may be an early event in Barrett's pathogenesis. CDX1/2 targets were, however, not enriched, suggesting that although CDX1/2 activation reportedly plays a role in BM development, it may not be an initial event. Our findings highlight new areas for investigation in the earliest stages of BM pathogenesis of oesophageal diseases and new potential therapeutic targets.

Loss of glutathione peroxidase 7 promotes TNF-α-induced NF-κB activation in Barrett's carcinogenesis

Esophageal adenocarcinoma (EAC) is a classic example of inflammation-associated cancer, which develops through GERD (gastroesophageal reflux disease)-Barrett's esophagus (BE)-dysplasia-adenocarcinoma sequence. The incidence of EAC has been rising rapidly in the USA and Western countries during the last few decades. The functions of glutathione peroxidase 7 (GPX7), an antioxidant enzyme frequently silenced during Barrett's tumorigenesis, remain largely uncharacterized. In this study, we investigated the potential role of GPX7 in regulating nuclear factor-kappaB (NF-κB) activity in esophageal cells. Western blot analysis, immunofluorescence and luciferase reporter assay data indicated that reconstitution of GPX7 expression in CP-A (non-dysplastic BE cells) and FLO-1 (EAC cells) abrogated tumor necrosis factor-α (TNF-α)-induced NF-κB transcriptional activity (P < 0.01) and nuclear translocation of NF-κB-p65 (P = 0.01). In addition, we detected a marked reduction in phosphorylation levels of components of NF-κB signaling pathway, p-p65 (S536), p-IκB-α (S32) and p-IKKα/β (S176/180), as well as significant suppression in induction of NF-κB target genes [TNF-α, interleukin (IL)-6, IL-8, IL-1β, CXCL-1 and CXCL-2] following treatment with TNF-α in GPX7-expressing FLO-1 cells as compared with control cells. We validated these effects by knockdown of GPX7 expression in HET1A (normal esophageal squamous cells). We found that GPX7-mediated suppression of NF-κB is independent of reactive oxygen species level and GPX7 antioxidant function. Further mechanistic investigations demonstrated that GPX7 promotes protein degradation of TNF-receptor 1 (TNFR1) and TNF receptor-associated factor 2 (TRAF2), suggesting that GPX7 modulates critical upstream regulators of NF-κB. We concluded that the loss of GPX7 expression is a critical step in promoting the TNF-α-induced activation of proinflammatory NF-κB signaling, a major player in GERD-associated Barrett's carcinogenesis.

Single nucleotide polymorphisms of caudal type homeobox 1 and 2 are associated with Barrett's esophagus

BACKGROUND

Barrett's esophagus (BE), the premalignant lesion of esophageal adenocarcinoma, is believed to develop as a result of chronic gastroesophageal reflux disease (GERD). Approximately 10 % of subjects with GERD progress to BE. Genetic, epigenetic and other risk factors may contribute to this inter-individual variability. Caudal type homeobox 1 (Cdx1) and Caudal type homeobox 2 (Cdx2) play important regulatory roles in the development of human BE.

AIMS

To determine associations between Cdx1 and Cdx2 single nucleotide polymorphisms (SNPs) and BE.

METHODS

Genomic DNA was extracted from blood samples collected from BE (n = 109) and GERD (n = 223) patients for genotyping of 5 SNPs each of Cdx1 and Cdx2 using TaqMan allelic discrimination assays. Odds ratios and 95 % confidence intervals of SNPs and haplotypes were calculated with a logistic regression model adjusted for factors including age, sex and hiatal hernia. Interactions between genetic variants and these three risk factors were also analyzed.

RESULTS

Older age (≥50 years), male sex and hiatal hernia were significantly associated with BE (P < 0.001). Five variants of Cdx1 SNPs (rs3776082, rs717746 and rs3776083), one Cdx1 haplotype, and three variants of Cdx2 SNPs (rs4769585 and rs3812863) were associated with BE (P < 0.05). Statistically significant interactions were detected between most of these SNPs and the three risk factors (P < 0.05).

CONCLUSION

Certain SNPs of Cdx1 and Cdx2 and their interactions with other risk factors are associated with BE, and may contribute to human susceptibility to BE.

Reduced expression of αGlcNAc in Barrett's oesophagus adjacent to Barrett's adenocarcinoma--a possible biomarker to predict the malignant potential of Barrett's oesophagus

AIMS

Gastric gland mucin contains O-glycans exhibiting terminal α1,4-linked N-acetylglucosamine residues (αGlcNAc). Recently we demonstrated that mice deficient in αGlcNAc in gastric gland mucin develop gastric adenocarcinoma spontaneously, indicating that αGlcNAc is a tumour suppressor for gastric cancer. However, the role of αGlcNAc in Barrett's oesophagus (BO) remains unknown. In this study, we investigated whether reduced αGlcNAc expression in BO is associated with development of Barrett's adenocarcinoma (BAC).

METHODS AND RESULTS

Thirty-five BO lesions adjacent to BAC were examined by immunohistochemistry for αGlcNAc, MUC6 and CDX2. As controls, 35 BO lesions without BAC obtained from patients with oesophageal squamous cell carcinoma were also analysed. Expression of αGlcNAc relative to its scaffold MUC6 in BO adjacent to BAC was reduced significantly compared to control BO. Decreased αGlcNAc expression in BO adjacent to BAC was particularly significant in patients with smaller tumour size (<20 mm) and minimal invasion of tumour cells to the superficial muscularis mucosae. There was also a significant inverse correlation between αGlcNAc and CDX2 expression in BO adjacent to BAC.

CONCLUSIONS

Decreased expression of αGlcNAc compared with MUC6 in BO is a possible hallmark in predicting BAC development.

[Barrett's esophagus: analyses from human and experimental animal studies]

Whereas attention in the past has been focused on goblet cells as the primary marker for Barrett's esophagus (BE), the recent change in the definition now includes the non-goblet cell columnar cell-lined esophagus. In the present study the histological features of neoplasia of the lower esophagus and esophago-gastric junction in a German cohort were examined using immunohistochemical staining for MUC, CD10, intestinal and gastric type major tight junction proteins (claudins). Experimental studies using rat duodenogastric content reflux models have also been performed and data show that most neoplastic lesions of the esophageal glands in humans express gastric mucin phenotypes. Cardiac type mucosa was the main histological type in the surrounding mucosa of neoplastic lesions; however, most cardiac type mucosa has intestinal type tight junction proteins. BE with goblet cells has been reported to originate from stem cells located in the basal layer of esophageal squamous cell epithelium in previous models. However, the cardiac type mucosa seems to develop from the site of the stomach and not from the basal layer of esophageal squamous cell epithelium according to our model.

Aberrant expression of Wnt and Notch signal pathways in Barrett's esophagus

BACKGROUND

Specialized intestinal metaplasia (SIM) mucosa observed in Barrett's esophagus (BE) has been a hot research topic due to the close relationship with adenocarcinoma of esophagus (ACE). Earlier studies found that SIM mucosa was similar to normal intestinal epithelium on morphology and histology. The signal pathway involved in conformation of intestinal epithelium may be a critical initiator for BE.

METHODS

The expressions of key regulators (Tcf4, Cdx2, Hes1 and Math1) in Wnt and Notch signal pathways were measured in 41 paired esophageal biopsies. Cell morphological changes in normal esophagus were compared among groups treated by acid, bile acid and the mixture of both media.

RESULTS

The expression levels of regulators (Tcf4, Cdx2, Hes1 and Math1) were found significantly increased in SIM, C ≥ 3Mn and high-grade dysplasia (HGD) groups. Distinct ultrastructure changes and highly expressed key regulators were also detected at the seventh day for group treated by 400 μmol bile acid.

CONCLUSIONS

Aberrant expressed regulators in Wnt and Notch pathways were observed in BE tissue and normal esophageal cells treated by acid, bile acid and the mixture of both media. This study provided preliminary data to understand the mechanism of BE conformation.

GC-C gene silencing inhibits the growth of subcutaneously implanted gastric tumors in nude mice

AIM: To study the effect of GC-C gene silencing on the biological behaviors of subcutaneously implanted gastric tumors and to explore the possible mechanisms involved.

METHODS: Non-transfected SGC-7901 cells (SGC-7901 group), SGC-7901 cells transfected cell with an empty plasmid (PRNA group), and those transfected with a shRNA targeting the GC-C gene (GC-C-shRNA group) were subcutaneously inoculated into nude mice. Then, the histologically intact xenograft tissues were subcutaneously transplanted to nude mice to observe the condition of nude mice and determine the rate of tumor survival and growth velocity. The levels of GC-C mRNA and protein were determined by RFQ-PCR and Western blot, respectively. The heteromorphism and necrosis of tumor cells were observed after HE staining. The expression of CXCR4 protein was detected by Western blot and immunohistochemistry.

RESULTS: The rate of tumor survival and the condition of nude mice did not differ significantly among the three groups. Compared to the SGC-7901 group and PRNA group, the tumors grew more slowly and became smaller in the GC-C-shRNA group (all P < 0.05). The reduced rate of tumor growth velocity and volume in the GC-C-shRNA group were 33.7% and 33.2%, respectively, and GC-C gene silencing efficiency was 66.8% and 64.4%, respectively (P < 0.05). The expression of GC-C protein decreased by 50.0% and 49.6%, respectively (P < 0.05), and the degree of tumor heteromorphism and necrosis and expression of CXCR4 protein in the GC-C-shRNA group decreased obviously (all P < 0.05).

CONCLUSION: GC-C gene silencing slows the growth velocity of gastric tumors in vivo possibly in a CXCR4-dependent manner.

Notch signaling pathway and Cdx2 expression in the development of Barrett's esophagus

Cdx2 expression in esophageal stem cells induced by reflux bile acids may be an important factor for development of Barrett's esophagus, whereas Notch signaling is a molecular signaling pathway that plays an important role in the determination of cell differentiation. ATOH1 (a factor associated with Notch signaling) plays an important role in differentiation of stem cells into goblet cells. However, the relationship between the Notch signaling pathway and Cdx2 expression in the development of Barrett's esophagus has not been explored. The aim of this study was to investigate the interrelationship between Notch signaling and Cdx2 in esophageal epithelial cells. The expressions of Cdx2, MUC2, and intracellular signaling molecules related to Notch signaling (Notch1, Hes1, and ATOH1) were examined using real-time polymerase chain reaction (PCR) and immunohistochemical staining with biopsy specimens obtained from esophageal intestinal metaplasia (IM) with goblet cells (IM⁺) and columnar epithelium not accompanied by goblet cells (IM⁻). For in vitro experiments, we employed human esophageal epithelial cell lines (OE33, OE19, and Het-1A). After forced Cdx2 expression by applying a Cdx2 expression vector to the cells, changes in the expressions of Notch1, Hes1, ATOH1, Cdx2, and MUC2 were analyzed by real-time PCR and western blot analysis. Changes in expressions of Notch1, Hes1, ATOH1, Cdx2, and MUC2 in cells were analyzed following stimulation with bile acids in the presence or absence of Cdx2 blocking with Cdx2-siRNA. Suppressed Hes1 and enhanced ATOH1 and MUC2 expressions were identified in IM⁺ specimens. Forced expression of Cdx2 in cells suppressed Hes1, and enhanced ATOH1 and MUC2 expressions, whereas bile acids suppressed Hes1, and enhanced ATOH1, Cdx2, and MUC2 expressions. On the other hand, these effects were blocked by siRNA-based Cdx2 downregulation. Enhanced expression of Cdx2 by stimulation with bile acids may induce intestinal differentiation of esophageal columnar cells by interaction with the Notch signaling pathway.

Gastro-oesophageal reflux disease is associated with up-regulation of desmosomal components in oesophageal mucosa

AIMS

Gastro-oesophageal reflux disease (GERD) is associated with impaired epithelial barrier function. This study was aimed at investigating the role of desmosomal proteins in relation to GERD.

METHODS AND RESULTS

Ninety-five patients with GERD-related symptoms (erosive, n = 51; non-erosive, n = 44) and 27 patients lacking those symptoms were included. Endoscopic and histological characterization of oesophagitis was performed according to the Los Angeles and Ismeil-Beigi criteria, respectively. Multiple biopsies were taken from the oesophageal mucosa of each patient. Gene expression analysis of plakoglobin, desmoglein-1, desmoglein-2 and desmoglein-3 was performed by quantitative real time (RT)-polymerase chain reaction and immunohistochemistry in the oesophageal mucosa. Routine histology revealed specific GERD-related alterations, such as dilatation of intercellular spaces (DIS), basal cell hyperplasia (BCH), and elongation of the papillae, in the oesophageal mucosa of patients with GERD, as compared with controls (all parameters: P < 0.05). All four genes and corresponding proteins were found to be up-regulated by between 1.7 and 8.1-fold (transcript level, P < 0.05; protein level, P < 0.05). Induced gene expression levels of plakoglobin, desmoglein-1 and desmoglein-2 correlated significantly with DIS and BCH.

CONCLUSIONS

Taken together, the uniform up-regulation of desmosomal genes/proteins in the oesophageal mucosa of patients with GERD supports the concept of architectural and molecular changes in the desmosomal compartment in the pathogenesis of GERD.

Cdx function is required for maintenance of intestinal identity in the adult

The homeodomain transcription factors Cdx1 and Cdx2 are expressed in the intestinal epithelium from early development, with expression persisting throughout the life of the animal. While our understanding of the function of Cdx members in intestinal development has advanced significantly, their roles in the adult intestine is relatively poorly understood. In the present study, we found that ablation of Cdx2 in the adult small intestine severely impacted villus morphology, proliferation and intestinal gene expression patterns, resulting in the demise of the animal. Long-term loss of Cdx2 in a chimeric model resulted in loss of all differentiated intestinal cell types and partial conversion of the mucosa to a gastric-like epithelium. Concomitant loss of Cdx1 did not exacerbate any of these phenotypes. Loss of Cdx2 in the colon was associated with a shift to a cecum-like epithelial morphology and gain of cecum-associated genes which was more pronounced with subsequent loss of Cdx1. These findings suggest that Cdx2 is essential for differentiation of the small intestinal epithelium, and that both Cdx1 and Cdx2 contribute to homeostasis of the colon.

Molecular mechanisms of Barrett's esophagus

Barrett's esophagus (BE) is defined as the metaplastic conversion of esophageal squamous epithelium to intestinalized columnar epithelium. As a premalignant lesion of esophageal adenocarcinoma (EAC), BE develops as a result of chronic gastroesophageal reflux disease (GERD). Many studies have been conducted to understand the molecular mechanisms of this disease. This review summarizes recent results involving squamous and intestinal transcription factors, signaling pathways, stromal factors, microRNAs, and other factors in the development of BE. A conceptual framework is proposed to guide future studies. We expect elucidation of the molecular mechanisms of BE to help in the development of improved management of GERD, BE, and EAC.

Ectopic expression of guanylyl cyclase C and endogenous ligand guanylin correlates significantly with Helicobacter pylori infection in gastric carcinogenesis

The molecular mechanisms leading to gastric carcinogenesis still remain unclear. Recently, several studies demonstrated that over-expression of guanylyl cyclase C (GCC) has been detected in intestinal-type gastric cancer (GC) and precursor lesions. Our objective was to explore the expression levels of GCC and endogenous ligands guanylin (GN) and uroguanylin (UGN) and the correlation between Helicobacter pylori (H. pylori) and GCC, GN, and UGN expressions in patients at different stages from normal mucosa to superficial gastritis, atrophic gastritis, intestinal metaplasia (IM), dysplasia, and finally adenocarcinoma. The expression of GCC and GN was absent in the distal normal gastric tissues and superficial gastritis in all cases, whereas they were measured in IM, dysplasia, and GC. The expression of GCC and GN was closely related to intestinal-type GC. From superficial gastritis to gastric carcinomas, the H. pylori positive rate was 19.7, 33.3, 69.6, 80.0, and 82.1%, respectively. The positive correlation was found between GCC and GN in IM, dysplasia, and GC. Also, the positive correlation was found between GCC, GN, and H. pylori infection in them. These results demonstrate that the detection of GCC and GN will be beneficial to diagnosis human gastric carcinoma and precancerous lesions. Ectopic expression of GCC and GN in human gastric mucosa and H. pylori infection may play an important role in the carcinogenesis of the intestinal-type GC.

Bile acid-induced expression of activation-induced cytidine deaminase during the development of Barrett's oesophageal adenocarcinoma

Activation-induced cytidine deaminase (AID) induces somatic mutations in various host genes of non-lymphoid tissues, thereby contributing to carcinogenesis. We recently demonstrated that Helicobacter pylori infection and/or proinflammatory cytokine stimulation triggers aberrant AID expression in gastric epithelial cells, causing mutations in the tumour-suppressor TP53 gene. The findings of the present study provide evidence of ectopic AID expression in Barrett's oesophagus and Barrett's oesophageal adenocarcinoma, a cancer that develops under chronic inflammatory conditions. Immunoreactivity for endogenous AID was observed in 24 of 28 (85.7%) specimens of the columnar cell-lined Barrett's oesophagus and in 20 of 22 (90.9%) of Barrett's adenocarcinoma, whereas weak or no AID protein expression was detectable in normal squamous epithelial cells of the oesophagus. We validated these results by analysing tissue specimens from another cohort comprising 16 cases with Barrett's oesophagus and four cases with Barrett's adenocarcinoma. In vitro treatment of human non-neoplastic oesophageal squamous-derived cells with sodium salt deoxycholic acid induced ectopic AID expression via the nuclear factor-kappaB activation pathway. These findings suggest that aberrant AID expression occurs in a substantial proportion of Barrett's epithelium, at least in part due to bile acid stimulation. Considering the genotoxic activity of AID, our current findings suggest that aberrant AID expression might enhance the susceptibility to genetic alterations in Barrett's columnar-lined epithelial cells, leading to cancer development.