Key elements of the BMP/SMAD pathway co-localize with CDX2 in intestinal metaplasia and regulate CDX2 expression in human gastric cell lines

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.

MicroRNA-148b secreted by bovine oviductal extracellular vesicles enhance embryo quality through BPM/TGF-beta pathway

BACKGROUND

Extracellular vesicles (EVs) and their cargoes, including MicroRNAs (miRNAs) play a crucial role in cell-to-cell communication. We previously demonstrated the upregulation of bta-mir-148b in EVs from oviductal fluid of cyclic cows. This miRNA is linked to the TGF-β pathway in the cell proliferation. Our aim was to verify whether miR-148b is taken up by embryos through gymnosis, validate its target genes, and investigate the effect of miR-148b supplementation on early embryo development and quality.

METHODS

Zygotes were cultured in SOF + 0.3% BSA (Control) or supplemented with: 1 µM miR-148b mimics during: D1-D7 (miR148b) or D1-D4 (miR148b-OV: representing miRNA effect in the oviduct) or D4-D7 (miR148b-UT: representing miRNA effect in the uterus) or 1 µM control mimics was used during: D1-D7 (CMimic). Embryos at ≥ 16-cells and D7 blastocysts (BD7) were collected to examine the mRNA abundance of transcripts linked to the TGF-β pathway (TGFBR2, SMAD1, SMAD2, SMAD3, SMAD5, BMPR2, RPS6KB1, POU5F1, NANOG), total cell number (TC), trophectoderm (TE), and inner cell mass (ICM) were also evaluated. One-way ANOVA was used for all analyses.

RESULTS

We demonstrated that miR-148b can be taken up in both 16-cell embryos and BD7 by gymnosis, and we observed a decrease in SMAD5 mRNA, suggesting it's a potential target of miR-148b. Cleavage and blastocysts rates were not affected in any groups; however, supplementation of miR-148b mimics had a positive effect on TC, TE and ICM, with values of 136.4 ± 1.6, 92.5 ± 0.9, 43.9 ± 1.3 for miR148b and 135.3 ± 1.5, 92.6 ± 1.2, 42.7 ± 0.8, for miR148b-OV group. Furthermore, mRNA transcripts of SMAD1 and SMAD5 were decreased (P ≤ 0.001) in 16-cell embryos and BD7 from miR148b and miR148b-OV groups, while POU5F1 and NANOG were upregulated (P ≤ 0.001) in BD7 and TGFBR2 was only downregulated in 16-cell embryos. pSMAD1/5 levels were higher in the miR148b and miR148b-OV groups.

CONCLUSIONS

Our findings suggest that supplementation of bta-miR-148b mimics during the entire culture period (D1 - D7) or from D1 - D4 improves embryo quality and influences the TGF-β signaling pathway by altering the transcription of genes associated with cellular differentiation and proliferation. This highlights the importance of miR-148b on embryo quality and development.

Metabolic switching, growth kinetics and cell yields in the scalable manufacture of stem cell-derived insulin-producing cells

BACKGROUND

Diabetes is a disease affecting over 500 million people globally due to insulin insufficiency or insensitivity. For individuals with type 1 diabetes, pancreatic islet transplantation can help regulate their blood glucose levels. However, the scarcity of cadaveric donor islets limits the number of people that could receive this therapy. To address this issue, human pluripotent stem cells offer a potentially unlimited source for generating insulin-producing cells through directed differentiation. Several protocols have been developed to make stem cell-derived insulin-producing cells. However, there is a lack of knowledge regarding the bioprocess parameters associated with these differentiation protocols and how they can be utilized to increase the cell yield.

METHODS

We investigated various bioprocess parameters and quality target product profiles that may influence the differentiation pipeline using a seven-stage protocol in a scalable manner with CellSTACKs and vertical wheel bioreactors (PBS-Minis).

RESULTS

Cells maintained > 80% viability through all stages of differentiation and appropriately expressed stage-specific markers. During the initial four stages leading up to the development of pancreatic progenitors, there was an increase in cell numbers. Following pancreatic progenitor stage, there was a gradual decrease in the percentage of proliferative cells, as determined by Ki67 positivity, and a significant loss of cells during the period of endocrine differentiation. By minimizing the occurrence of aggregate fusion, we were able to enhance cell yield during the later stages of differentiation. We suggest that glucose utilization and lactate production are cell quality attributes that should be considered during the characterization of insulin-producing cells derived from stem cells. Our findings also revealed a gradual metabolic shift from glycolysis, during the initial four stages of pancreatic progenitor formation, to oxidative phosphorylation later on during endocrine differentiation. Furthermore, the resulting insulin-producing cells exhibited a response to several secretagogues, including high glucose.

CONCLUSION

This study demonstrates process parameters such as glucose consumption and lactate production rates that may be used to facilitate the scalable manufacture of stem cell-derived insulin-producing cells.

The prognostic potential of CDX2 in colorectal cancer: Harmonizing biology and clinical practice

Adjuvant chemotherapy following surgical intervention remains the primary treatment option for patients with localized colorectal cancer (CRC). However, a significant proportion of patients will have an unfavorable outcome after current forms of chemotherapy. While reflecting the increasing complexity of CRC, the clinical application of molecular biomarkers provides information that can be utilized to guide therapeutic strategies. Among these, caudal-related homeobox transcription factor 2 (CDX2) emerges as a biomarker of both prognosis and relapse after therapy. CDX2 is a key transcription factor that controls intestinal fate. Although rarely mutated in CRC, loss of CDX2 expression has been reported mostly in right-sided, microsatellite-unstable tumors and is associated with aggressive carcinomas. The pathological assessment of CDX2 by immunohistochemistry can thus identify patients with high-risk CRC, but the evaluation of CDX2 expression remains challenging in a substantial proportion of patients. In this review, we discuss the roles of CDX2 in homeostasis and CRC and the alterations that lead to protein expression loss. Furthermore, we review the clinical significance of CDX2 assessment, with a particular focus on its current use as a biomarker for pathological evaluation and clinical decision-making. Finally, we attempt to clarify the molecular implications of CDX2 deficiency, ultimately providing insights for a more precise evaluation of CDX2 protein expression.

Inhibition of BMP2 and BMP4 Represses Barrett's Esophagus While Enhancing the Regeneration of Squamous Epithelium in Preclinical Models

BACKGROUND & AIMS

Barrett's esophagus is considered to be a metaplastic lesion that predisposes for esophageal adenocarcinoma. Development of Barrett's esophagus is considered to be driven by sonic hedgehog mediated bone morphogenetic protein (BMP) signaling. We aimed to investigate in preclinical in vivo models whether targeting canonical BMP signaling could be an effective treatment for Barrett's esophagus.

METHODS AND RESULTS

Selective inhibition of BMP2 and BMP4 within an in vivo organoid model of Barrett's esophagus inhibited development of columnar Barrett's cells, while favoring expansion of squamous cells. Silencing of noggin, a natural antagonist of BMP2, BMP4, and BMP7, in a conditional knockout mouse model induced expansion of a Barrett's-like neo-columnar epithelium from multi-lineage glands. Conversely, in this model specific inhibition of BMP2 and BMP4 led to the development of a neo-squamous lineage. In an ablation model, inhibition of BMP2 and BMP4 resulted in the regeneration of neo-squamous epithelium after the cryoablation of columnar epithelium at the squamocolumnar junction. Through lineage tracing the generation of the neo-squamous mucosa was found to originate from K5+ progenitor squamous cells.

CONCLUSIONS

Here we demonstrate that specific inhibitors of BMP2 and BMP4 attenuate the development of Barrett's columnar epithelium, providing a novel potential strategy for the treatment of Barrett's esophagus and the prevention of esophageal adenocarcinoma.

The role of bile acid in intestinal metaplasia

A precancerous lesion of gastric cancer (GC), intestinal metaplasia (IM) is a pathological transformation of non-intestinal epithelium into an intestinal-like mucosa. It greatly raises the risk of developing the intestinal type of GC, which is frequently observed in the stomach and esophagus. It is understood that esophageal adenocarcinoma's precursor lesion, chronic gastroesophageal reflux disease (GERD), is what causes Barrett's esophagus (BE), an acquired condition. Recently, Bile acids (BAs), which are one of the compositions of gastric and duodenal contents, have been confirmed that it led to the occurrence and development of BE and gastric intestinal metaplasia (GIM). The objective of the current review is to discuss the mechanism of IM induced by bile acids. This review serves as a foundation for further research aimed at improving the way BE and GIM are currently managed.

Morphogen Signals Shaping the Gastric Glands in Health and Disease

The adult gastric mucosa is characterised by deep invaginations of the epithelium called glands. These tissue architectural elements are maintained with the contribution of morphogen signals. Morphogens are expressed in specific areas of the tissue, and their diffusion generates gradients in the microenvironment. Cells at different positions in the gland sense a specific combination of signals that instruct them to differentiate, proliferate, regenerate, or migrate. Differentiated cells perform specific functions involved in digestion, such as the production of protective mucus and the secretion of digestive enzymes or gastric acid. Biopsies from gastric precancerous conditions usually display tissue aberrations and change the shape of the glands. Alteration of the morphogen signalling microenvironment is likely to underlie those conditions. Furthermore, genes involved in morphogen signalling pathways are found to be frequently mutated in gastric cancer. We summarise the most recent findings regarding alterations of morphogen signalling during gastric carcinogenesis, and we highlight the new stem cell technologies that are improving our understanding of the regulation of human tissue shape.

Upregulation of oncogene Activin A receptor type I by Helicobacter pylori infection promotes gastric intestinal metaplasia via regulating CDX2

BACKGROUND

Activin A receptor type I (ACVR1) is involved in tumorigenesis. However, the underlying molecular mechanisms of ACVR1 in gastric cancer (GC) and its association with Helicobacter pylori remained unclear.

MATERIALS AND METHODS

The Cancer Genome Atlas (TCGA) and Gene Expression Profiling Interactive Analysis (GEPIA) database were utilized to explore the ACVR1 expression in GC and normal control and its association with survival. The ACVR1 was knocked out using CRISPR/Cas-9; RNA sequencing analysis was performed in AGS cells with ACVR1 knockout and normal control. Functional experiments (CCK-8, colony-forming, and transwell assays) were conducted to demonstrate the role of ACVR1 in cell proliferation, invasion, and metastasis. H. pylori-infected C57/BL6 models were established. ACVR1, p-Smad1/5, and CDX2 were detected in AGS cells cocultured with H. pylori strains. The CDX2 and key elements of BMP signaling pathway were detected in AGS cells with ACVR1 knockout and normal control. In addition, Immunohistochemistry was performed to detect the ACVR1 and CDX2 expression in gastric samples.

RESULTS

ACVR1 expression was higher in GC than normal control from TCGA, GEPIA, and samples collected from our hospital (p < 0.05). ACVR1 promoted cell proliferation, migration, and invasion in vitro. Both cagA⁺ and cagA^- H. pylori could upregulate the expression ACVR1 (p < 0.05). Downregulation of ACVR1 inhibited the H. pylori-induced cell proliferation, migration, and invasion (p < 0.05). H. pylori increased the expression of p-Smad 1/5 and CDX2. The CDX2 and key elements of BMP signaling pathway were downregulated in AGS cells with ACVR1 knockout. ACVR1 and CDX2 were upregulated in the stage of intestinal metaplasia (IM). Moreover, ACVR1 and CDX2 expressions were higher in H. pylori-positive group than H. pylori-negative group (p < 0.05).

CONCLUSION

Our data indicate that H. pylori infection increases ACVR1 expression, promoting gastric IM via regulating CDX2, which is an essential step in H. pylori carcinogenesis.

The role of SOX family transcription factors in gastric cancer

Gastric cancer (GC) is a leading cause of death worldwide. GC is the third-most common cause of cancer-related death after lung and colorectal cancer. It is also the fifth-most commonly diagnosed cancer. Accumulating evidence has revealed the role of signaling networks in GC progression. Identification of these molecular pathways can provide new insight into therapeutic approaches for GC. Several molecular factors involved in GC can play both onco-suppressor and oncogene roles. Sex-determining region Y (Sry)-box-containing (SOX) family members are transcription factors with a well-known role in cancer. SOX proteins can bind to DNA to regulate cellular pathways via a highly conserved domain known as high mobility group (HMG). In the present review, the roles of SOX proteins in the progression and/or inhibition of GC are discussed. The dual role of SOX proteins as tumor-promoting and tumor-suppressing factors is highlighted. SOX members can affect upstream mediators (microRNAs, long non-coding RNAs and NF-κB) and down-stream mediators (FAK, HIF-1α, CDX2 and PTEN) in GC. The possible role of anti-tumor compounds to target SOX pathway members in GC therapy is described. Moreover, SOX proteins may be used as diagnostic or prognostic biomarkers in GC.

CDX2 and Reg IV expression and correlation in gastric cancer

Background

Ectopic expression of CDX2 is associated with the development and progression of gastric cancer. Previous studies showed that CDX2 may be an upstream regulator of Reg IV expression in gastric cancer, and our previous report showed that Reg IV upregulated SOX9 expression and enhanced cell migration and invasion in gastric cancer cells. However, the regulatory roles of CDX2 have not been clarified in gastric cancer, and the correlation between CDX2 and Reg IV requires further study.

Methods

CDX2 and Reg IV were examined in gastric cancer specimens and paired adjacent tissues via real-time PCR and immunohistochemistry (IHC). The association between CDX2 and Reg IV was assessed using the χ²-test and Spearman’s rank correlation. To verify their relationship, knockdown and exogenous expression of CDX2 or Reg IV were performed in AGS and MKN-45 gastric cancer cells, and their expression was subsequently analyzed via a real-time PCR and western blotting. Wound-healing and Transwell assays were used to examine migration and invasion in AGS and MKN-45 cells following CDX2 silencing or overexpression.

Results

A positive correlation was observed between CDX2 and Reg IV expression at the mRNA and protein levels in gastric cancer tissues. CDX2 silencing significantly downregulated Reg IV expression, and CDX2 overexpression significantly upregulated Reg IV expression in AGS and MKN-45 cells. Neither Reg IV silencing nor overexpression had any effect on CDX2 protein expression in AGS or MKN-45 cells, even though both affected the expression of CDX2 mRNA. Functionally, CDX2 silencing significantly inhibited cell migration and invasion, and CDX2 overexpression significantly promoted cell migration and invasion in AGS and MKN-45 cells.

Conclusions

Our findings demonstrate that CDX2 expression was positively correlated with that of Reg IV in gastric cancer, and CDX2 promoted cell migration and invasion through upregulation of Reg IV expression in AGS and MKN-45 cells.

Caudal type homeoboxes as a driving force in Helicobacter pylori infection-induced gastric intestinal metaplasia

(H. pylori), a common pathogenic bacterium in the stomach, has been demonstrated to be a major cause of gastric cancer (GC). The typical pathological evolution of H. pylori infection-induced GC involves development from gastric atrophy, via intestinal metaplasia (IM) and dysplasia, to intestinal-type GC. During this process, IM is considered to be an "irreversible point" that significantly increases the risk for GC. Therefore, the elucidation of the mechanism underlying IM is of great significance for the prevention and treatment of gastric mucosal carcinogenesis associated with H. pylori infection. Caudal type homeoboxes (CDXs) are transcription factors involved in intestinal differentiation establishment and the maintenance of normal intestinal mucosa and IM. H. pylori infection increases the expression of CDXs through epigenetic regulation, the nuclear factor-kappaB signaling pathway and its downstream proinflammatory factors, and the transforming growth factor-beta signaling pathway, leading to the progression from normal gastric mucosa to IM. However, the precise mechanisms of gastric intestinal metaplasia have not yet been fully elucidated. In this review, we focus on research progress revealing the functions of CDXs in H. pylori infection-induced IM, as well as the regulators modulating this process.

BMP4 promotes the metastasis of gastric cancer by inducing epithelial-mesenchymal transition via ID1

Epithelial-mesenchymal transition (EMT) is a crucial process for cancer cells to acquire metastatic potential, which primarily causes death in gastric cancer (GC) patients. Bone morphogenetic protein 4 (BMP4) is a member of the TGF-β family that plays an indispensable role in human cancers. However, little is known about its roles in GC metastasis. In this study, BMP4 was found to be frequently overexpressed in GC tissues and was correlated with poor patient's prognosis. BMP4 was upregulated in GC cell lines and promoted EMT and metastasis of GC cells both in vitro and in vivo, whereas knockdown of BMP4 significantly inhibited EMT and metastasis of GC cells. Furthermore, the inhibitor of DNA binding 1 (also known as DNA-binding protein inhibitor ID1) was identified as a downstream target of BMP4 using PCR arrays and was upregulated via SMAD1/5/8 phosphorylation. ID1 knockdown attenuated BMP4-induced EMT and invasion in GC cells. Moreover, ID1 overexpression in BMP4 knockdown cells restored the promotion of EMT and cell invasion. In summary, BMP4 induced EMT and promoted GC metastasis by upregulating ID1 expression. Antagonizing BMP4 could be a potential therapeutic strategy for GC metastasis.

BMP Signaling in Development, Stem Cells, and Diseases of the Gastrointestinal Tract

The bone morphogenetic protein (BMP) pathway is essential for the morphogenesis of multiple organs in the digestive system. Abnormal BMP signaling has also been associated with disease initiation and progression in the gastrointestinal (GI) tract and associated organs. Recent studies using animal models, tissue organoids, and human pluripotent stem cells have significantly expanded our understanding of the roles played by BMPs in the development and homeostasis of GI organs. It is clear that BMP signaling regulates GI function and disease progression that involve stem/progenitor cells and inflammation in a tissue-specific manner. In this review we discuss these new findings with a focus on the esophagus, stomach, and intestine.

Silencing Smad4 attenuates sensitivity of colorectal cancer cells to cetuximab by promoting epithelial‑mesenchymal transition

The aberrant expression of tumor suppressor Smad4 often occurs in colorectal cancer (CRC), and this phenomenon is believed to be associated with drug resistance. The present study aimed to investigate the effects of Smad4 on the sensitivity of CRC cells to cetuximab, and the possible mechanism underlying such an effect. A total of 629 colorectal adenocarcinoma cases were downloaded from The Cancer Genome Atlas (TCGA) database, and a Smad4 mutation rate of ~21% was demonstrated among the cases. Low expression of Smad4 was present in CRC tissues analyzed by TCGA and in four CRC cell lines, as determined by reverse transcription‑quantitative PCR (RT‑qPCR) and western blot analysis. Cell Counting kit‑8 (CCK‑8) was used to measure the effects of different concentrations of cetuximab on SW480 cell viability at 24 and 48 h. The results demonstrated that treatment of SW480 cells with 20 µg/ml cetuximab for 48 h markedly reduced cell viability. In addition, plasmids were transfected into SW480 cells to induce Smad4 silencing or overexpression. Silencing Smad4 attenuated the sensitivity of SW480 CRC cells to cetuximab; this effect was reflected in increased cell viability and slightly increased migration and invasion, as determined by CCK‑8, wound scratch and Transwell analyses. RT‑qPCR and western blotting was performed to assess the expression levels of apoptosis‑ and epithelial‑mesenchymal transition (EMT)‑related genes. Silencing Smad4 partly reversed the effects of cetuximab on the mRNA and protein expression levels of vimentin, Bax/Bcl‑2 and E‑cadherin. However, Smad4 overexpression enhanced SW480 cell sensitivity to cetuximab. In conclusion, Smad4 may serve a vital role in the sensitivity of CRC cells to chemotherapeutic drugs by promoting EMT.

Clinicopathological Characterization and Prognostic Implication of SMAD4 Expression in Colorectal Carcinoma

Background

SMAD family member 4 (SMAD4) has gained attention as a promising prognostic factor of colorectal cancer (CRC) as well as a key molecule to understand the tumorigenesis and progression of CRC.

Methods

We retrospectively analyzed 1,281 CRC cases immunohistochemically for their expression status of SMAD4, and correlated this status with clinicopathologic and molecular features of CRCs.

Results

A loss of nuclear SMAD4 was significantly associated with frequent lymphovascular and perineural invasion, tumor budding, fewer tumor-infiltrating lymphocytes, higher pT and pN category, and frequent distant metastasis. In contrast, tumors overexpressing SMAD4 showed a significant association with sporadic microsatellite instability. After adjustment for TNM stage, tumor differentiation, adjuvant chemotherapy, and lymphovascular invasion, the loss of SMAD4 was found to be an independent prognostic factor for worse 5-year progression-free survival (hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.01 to 1.60; p=.042) and 7-year cancer-specific survival (HR, 1.45; 95% CI, 1.06 to 1.99; p=.022).

Conclusions

We confirmed the value of determining the loss of SMAD4 immunohistochemically as an independent prognostic factor for CRC in general. In addition, we identified some histologic and molecular features that might be clues to elucidate the role of SMAD4 in colorectal tumorigenesis and progression.

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.

[Role of Inhibitory Transforming Growth Factor-β Signal Smad7 in Helicobacter pylori-associated Gastric Damage]

Background/Aims

Transforming growth factor-beta (TGF-β) is a cytokine implicated in the susceptibility, development, and progression of gastrointestinal cancer and certain other neoplasms. In the later stages of cancer, TGF-β not only acts as a bystander of host-immune response, but also contributes to cell growth, invasion, and metastasis. In the current study, we generated gastric mucosal cells that stably express Smad7, and explored the Helicobacter pylori-associated biological changes between mock-transfected and Smad7-transfected RGM1 cells.

Methods

RGM1 cells stably transfected with Smad7 were infected with H. pylori, and molecular changes in apoptotic markers and inflammatory mediators were examined. Several candidate genes were explored in Smad7-overexpressing cells after H. pylori infection.

Results

Overexpression of Smad7 in RGM1 cells significantly increased the H. pylori-induced cytotoxicity compared to mock-transfected cells. Exaggerated increases in inflammatory mediators, cyclooxygenase 2, inducible NO synthase, and augmented apoptosis were noted in Smad7-overexpressing cells, whereas mitigated heme oxygenase 1 was noted in Smad7- overexpressing cells. These phenomena were reversed in cells transfected with Smad7 siRNA.

Conclusions

These data suggest that inhibition of Smad7 is a possible target for mitigating H. pylori-associated inflammation.

Status of Epstein-Barr Virus Coinfection with Helicobacter pylori in Gastric Cancer

Epstein-Barr virus is a ubiquitous human herpesvirus whose primary infection causes mononucleosis, Burkett's lymphoma, nasopharyngeal carcinoma, autoimmune diseases, and gastric cancer (GC). The persistent infection causes malignancies in lymph and epithelial cells. Helicobacter pylori causes gastritis in human with chronic inflammation. This chronic inflammation is thought to be the cause of genomic instability. About 45%-word population have a probability of having both pathogens, namely, H. pylori and EBV. Approximately 180 per hundred thousand population is developing GC along with many gastric abnormalities. This makes GC the third leading cause of cancer-related death worldwide. Although lots of research are carried out individually for EBV and H. pylori, still there are very few reports available on coinfection of both pathogens. Recent studies suggested that EBV and H. pylori coinfection increases the occurrence of GC as well as the early age of GC detection comparing to individual infection. The aim of this review is to present status on coinfection of both pathogens and their association with GC.

SOX2 Inhibition Promotes Promoter Demethylation of CDX2 to Facilitate Gastric Intestinal Metaplasia

BACKGROUND

Gastric intestinal metaplasia (IM) is regarded as a premalignant lesion, conferring risks for gastric cancer development. An intestinal transcription factor, CDX2, plays a vital role in establishing and maintaining IM. SOX2, an HMG-box transcription factor, is expressed in normal gastric mucosa and downregulated in IM. Therefore, it is important to elucidate the mutual interaction of SOX2 and CDX2 in gastric IM.

AIMS

This study aims to evaluate the negative correlation between SOX2 and CDX2 in mRNA expression and promoter methylation and to illuminate the effect of SOX2 on the promoter methylation of CDX2.

METHODS

Immunohistochemistry, real-time PCR and methylation-specific polymerase chain reaction assays were performed to evaluate the expression and promoter methylation of SOX2 and CDX2 in IM tissues from patients. SOX2 knockdown and CDX2 overexpression were performed in GES-1 cells to further clarify the relationship between SOX2 and CDX2.

RESULTS

A negative correlation between SOX2 and CDX2 was found in 120 gastric IM specimens. Additionally, significant DNA demethylation of CDX2 promoter in clinical IM specimens was observed concomitantly with partial methylation of the SOX2 promoter. Furthermore, SOX2 knockdown in GES-1 cells triggered promoter demethylation of CDX2. Finally, the phenotype shift of gastric intestinal metaplasia in GES-1 cells, marked by MUC2 expression, was effectively induced by the combination of SOX2 RNAi and CDX2 overexpression.

CONCLUSIONS

Aberrant DNA methylation of SOX2 and CDX2 genes contributes to the development of IM. Notably, SOX2 may play a role in establishing and maintaining the methylation status of the CDX2 gene in gastric tissues and cells.

A SMAD4 mutation indicative of juvenile polyposis syndrome in a family previously diagnosed with Menetrier's disease

BACKGROUND

Menetrier's disease (MD) is a rare disease with unknown aetiology, characterized by hypertrophic folds within the fundus and body of the stomach.

AIMS

We investigated mutations of the candidate genes SMAD4, BMPR1A, TGF-α, and PDX1 within a family with MD.

METHODS

A large 4-generation family with MD was identified. This family had 5 cases of MD, 1 case of MD and juvenile polyposis syndrome (JPS) and 3 cases of JPS. Participants provided saliva for DNA extraction and completed a health questionnaire designed to assess conditions that may be found in patients with MD. Following pedigree analysis, we sequenced the coding regions of the SMAD4 and BMPR1A genes and the regulatory regions of the TGF-α and PDX1 genes in affected and non-affected family members.

RESULTS

No mutations were identified in the sequenced regions of BMPR1A, TGF-α, or PDX1. A dominant 1244_1247delACAG mutation of SMAD4 was identified in each of the subjects with JPS as well as in each of the subjects with MD. Although this mutation segregated with disease, there were also unaffected/undiagnosed carriers.

CONCLUSION

The 1244_1247delACAG mutation of SMAD4 is the cause of JPS and the likely cause of MD in a large family initially diagnosed with MD.

The characterization of an intestine-like genomic signature maintained during Barrett's-associated adenocarcinogenesis reveals an NR5A2-mediated promotion of cancer cell survival

Barrett’s oesophagus (BO), an intestinal-type metaplasia (IM), typically arising in conjunction with gastro-oesophageal reflux disease, is a prominent risk factor for the development of oesophageal adenocarcinoma (OAC). The molecular similarities between IM and normal intestinal tissues are ill-defined. Consequently, the contribution of intestine-enriched factors expressed within BO to oncogenesis is unclear. Herein, using transcriptomics we define the intestine-enriched genes expressed in meta-profiles of BO and OAC. Interestingly, 77% of the genes differentially expressed in a meta-profile of BO were similarly expressed in intestinal tissues. Furthermore, 85% of this intestine-like signature was maintained upon transition to OAC. Gene networking analysis of transcription factors within this signature revealed a network centred upon NR5A2, GATA6 and FOXA2, whose over-expression was determined in a cohort of BO and OAC patients. Simulated acid reflux was observed to induce the expression of both NR5A2 and GATA6. Using siRNA-mediated silencing and an NR5A2 antagonist we demonstrate that NR5A2-mediated cancer cell survival is facilitated through augmentation of GATA6 and anti-apoptotic factor BCL-XL levels. Abrogation of NR5A2-GATA6 expression in conjunction with BCL-XL co-silencing resulted in synergistically increased sensitivity to chemotherapeutics and photo-dynamic therapeutics. These findings characterize the intestine-like signature associated with IM which may have important consequences to adenocarcinogenesis.

Inactivation of NKX6.3 in the stomach leads to abnormal expression of CDX2 and SOX2 required for gastric-to-intestinal transdifferentiation

Intestinal metaplasia in gastric mucosa is considered a preneoplastic lesion that progresses to gastric cancer. However, the molecular networks underlying this lesion formation are largely unknown. NKX6.3 is known to be an important regulator in gastric mucosal epithelial differentiation. In this study, we characterized the effects of NKX6.3 that may contribute to gastric intestinal metaplasia. NKX6.3 expression was significantly reduced in gastric mucosae with intestinal metaplasia. The mRNA expression levels of both NKX6.3 and CDX2 predicted the intestinal metaplasia risk, with an area under the receiver operating characteristic curve value of 0.9414 and 0.9971, respectively. Notably, the NKX6.3 expression level was positively and inversely correlated with SOX2 and CDX2, respectively. In stable AGS(NKX6.3) and MKN1(NKX6.3) cells, NKX6.3 regulated the expression of CDX2 and SOX2 by directly binding to the promoter regions of both genes. Nuclear NKX6.3 expression was detected only in gastric epithelial cells without intestinal metaplasia. Furthermore, NKX6.3-induced TWSG1 bound to BMP4 and inhibited BMP4-binding activity to BMPR-II. These data suggest that NKX6.3 might function as a master regulator of gastric differentiation by affecting SOX2 and CDX2 expression and the NKX6.3 inactivation may result in intestinal metaplasia in gastric epithelial cells.

Differentiation reprogramming in gastric intestinal metaplasia and dysplasia: role of SOX2 and CDX2

AIMS

Intestinal metaplasia (IM), which results from de-novo expression of CDX2, and dysplasia are precursor lesions of gastric cancer that are associated with an increased risk for cancer development. There is much evidence suggesting a role for the transcription factor SOX2 in gastric differentiation. The aim of this study was to attempt to establish the relationship of SOX2 with CDX2 and with the differentiation reprogramming that characterizes gastric carcinogenesis, to assess their involvement in IM and dysplasia.

METHODS AND RESULTS

Characterization of gastric (SOX2, MUC5AC, and MUC6) and intestinal (CDX2 and MUC2) markers in normal gastric mucosa, in 55 foci of IM and in 26 foci of dysplasia, was performed by immunohistochemistry. SOX2 was expressed in the normal gastric mucosa, in the presumptive stem cell compartment, and was maintained in 7% of the complete (MUC5AC-negative) and 85% of the incomplete (MUC5AC-positive) IM subtypes. Twelve per cent of the dysplastic lesions expressed SOX2, and the association with MUC5AC was lost. CDX2 was present in all IMs and dysplastic lesions.

CONCLUSIONS

SOX2 is associated with gastric differentiation in incomplete IM and is lost in the progression to dysplasia, whereas CDX2 is acquired de novo in IM and maintained in dysplasia. This suggests that the balance between gastric and intestinal differentiation programmes impacts on the gastric carcinogenesis cascade progression.

Shigella dysenteriae modulates BMP pathway to induce mucin gene expression in vivo and in vitro

Mucosal epithelial cells in the intestine act as the first line of host defense against pathogens by increasing mucin production for clearance. Despite this fact, the underlying molecular mechanisms by which Shigella dysenteriae transduce mucin gene expression remain poorly defined. The goal of this study was to determine the role of Bone morphogenetic protein (BMP) pathway in mucin gene expression during S. dysenteriae infection. In this study we demonstrate that S. dysenteriae activates BMP signaling to induce MUC2 and MUC5AC gene expression in rat ileal loop model and in vitro. We also observed that BMP pathway regulates CDX2 expression which plays a critical role in induction of MUC2 gene during S. dysenteriae infection. In SMAD4 silenced cells S. dysenteriae infection did not abrogate MUC2 and MUC5AC gene expression whereas in CDX2 silenced cells it induces differential expression of MUC5AC gene. These results suggest that SMAD4-CDX2 induces MUC2 gene expression whereas SMAD4 directly influences differential expression of MUC5AC gene. Altogether, our results show that during S. dysenteriae infection the BMP pathway modulates inflammatory transcription factors CDX2 and SMAD4 to induce MUC2 and MUC5AC gene expression which plays a key role in the regulation of host mucosal defense thereby paving a cue for therapeutic application.

Methylation-mediated gene silencing as biomarkers of gastric cancer: A review

Despite a decline in the overall incidence of gastric cancer (GC), the disease remains the second most common cause of cancer-related death worldwide and is thus a significant global health problem. The best means of improving the survival of GC patients is to screen for and treat early lesions. However, GC is often diagnosed at an advanced stage and is associated with a poor prognosis. Current diagnostic and therapeutic strategies have not been successful in decreasing the global burden of the disease; therefore, the identification of reliable biomarkers for an early diagnosis, predictive markers of recurrence and survival and markers of drug sensitivity and/or resistance is urgently needed. The initiation and progression of GC depends not only on genetic alterations but also epigenetic changes, such as DNA methylation and histone modification. Aberrant DNA methylation is the most well-defined epigenetic change in human cancers and is associated with inappropriate gene silencing. Therefore, an increasing number of genes methylated at the promoter region have been targeted as possible biomarkers for different purposes, including early detection, classification, the assessment of the tumor prognosis, the development of therapeutic strategies and patient follow-up. This review article summarizes the current understanding and recent evidence regarding DNA methylation markers in GC with a focus on the clinical potential of these markers.

Temporal regulation of mRNAs for select bone morphogenetic proteins (BMP), BMP receptors and their associated SMAD proteins during bovine early embryonic development: effects of exogenous BMP2 on embryo developmental progression

BACKGROUND

We previously demonstrated embryotrophic actions of maternal (oocyte-derived) follistatin during bovine early embryogenesis. Classical actions of follistatin are attributed to inhibition of activity of growth factors including activins and bone morphogenetic proteins (BMP). However, temporal changes in BMP mRNA in early bovine embryos and the effects of exogenous BMP on embryo developmental progression are not understood. The objectives of present studies were to characterize mRNA abundance for select BMP, BMP receptors and BMP receptor associated SMADs during bovine oocyte maturation and early embryogenesis and determine effects of addition of exogenous BMP protein on early development.

METHODS

Relative abundance of mRNA for BMP2, BMP3, BMP7, BMP10, SMAD1, SMAD5, ALK3, ALK6, ALK2, BMPR2, ACVR2A and ACVR2B was determined by RT-qPCR analysis of germinal vesicle (GV) and in vitro matured metaphase II (MII) oocytes and in vitro produced embryos collected at pronuclear, 2-cell (C), 4C, 8C, 16C, morula and blastocyst stages. Effects of addition of recombinant human BMP2 (0, 1, 10 and 100 ng/ml) during initial 72 h of embryo culture on early cleavage (within 30 h post insemination), total cleavage, development to 8C-16C and blastocyst stages and blastocyst mRNA abundance for markers of inner cell mass (NANOG) and trophectoderm (CDX2) were also determined.

RESULTS

Abundance of mRNA for BMP2, BMP10, SMAD1, SMAD5, ALK3, ALK2, BMPR2 and ACVR2B was elevated in MII oocytes and/or pronuclear stage embryos (relative to GV) and remained elevated through the 8C -16C stages, whereas BMP3, BMP7 and ALK2 mRNAs were transiently elevated. Culture of embryos to the 8C stage in the presence of α-amanitin resulted in increased abundance for all of above transcripts examined relative to untreated 8C embryos. Effects of addition of exogenous BMP2 on early cleavage rates and rates of development to 8C-16C and blastocyst stages were not observed, but BMP2 treatment increased blastocyst mRNA for CDX2 and NANOG.

CONCLUSIONS

Abundance of maternally derived mRNAs for above BMP system components are dynamically regulated during oocyte maturation and early embryogenesis. Exogenous BMP2 treatment does not influence progression to various developmental endpoints, but impacts characteristics of resulting blastocysts. Results support a potential role for BMPs in bovine early embryogenesis.

Generation of insulin-producing β-like cells from human iPS cells in a defined and completely xeno-free culture system

Human induced pluripotent stem (hiPS) cells are considered a potential source for the generation of insulin-producing pancreatic β-cells because of their differentiation capacity. In this study, we have developed a five-step xeno-free culture system to efficiently differentiate hiPS cells into insulin-producing cells in vitro. We found that a high NOGGIN concentration is crucial for specifically inducing the differentiation first into pancreatic and duodenal homeobox-1 (PDX1)-positive pancreatic progenitors and then into neurogenin 3 (NGN3)-expressing pancreatic endocrine progenitors, while suppressing the differentiation into hepatic or intestinal cells. We also found that a combination of 3-isobutyl-1-methylxanthine (IBMX), exendin-4, and nicotinamide was important for the differentiation into insulin single-positive cells that expressed various pancreatic β-cell markers. Most notably, the differentiated cells contained endogenous C-peptide pools that were released in response to various insulin secretagogues and high levels of glucose. Therefore, our results demonstrate the feasibility of generating hiPS-derived pancreatic β-cells under xeno-free conditions and highlight their potential to treat patients with type 1 diabetes.

Antral atrophy, intestinal metaplasia, and preneoplastic markers in Mexican children with Helicobacter pylori-positive and Helicobacter pylori-negative gastritis

Chronic inflammation and infection are major risk factors for gastric carcinogenesis in adults. As chronic gastritis is common in Mexican children, diagnosis of Helicobacter pylori and other causes of gastritis are critical for the identification of children who would benefit from closer surveillance. Antral biopsies from 82 Mexican children (mean age, 8.3 ± 4.8 years) with chronic gastritis (36 H pylori+, 46 H pylori-) were examined for gastritis activity, atrophy, intestinal metaplasia (IM), and immunohistochemical expression of gastric carcinogenesis biomarkers caudal type homeobox 2 (CDX2), ephrin type-B receptor 4 (EphB4), matrix metalloproteinase 3 (MMP3), macrophage migration inhibitory factor (MIF), p53, β-catenin, and E-cadherin. Atrophy was diagnosed in 7 (9%) of 82, and IM, in 5 (6%) of 82 by routine histology, whereas 6 additional children (7%) (3 H pylori+) exhibited aberrant CDX2 expression without IM. Significant positive correlations were seen between EphB4, MMP3, and MIF (P<.0001). Atrophy and follicular pathology were more frequent in H pylori+ biopsies (P<.0001), whereas IM and CDX2 expression showed no significant correlation with H pylori status. Antral biopsies demonstrating atrophy, IM, and/or aberrant CDX2 expression were seen in 21.95% (18/82) of the children, potentially identifying those who would benefit from closer surveillance and preventive dietary strategies. Biomarkers CDX2, EphB4, MMP3, and MIF may be useful in the workup of pediatric gastritis.

Reduced expression of bone morphogenetic protein receptor IA in pancreatic cancer is associated with a poor prognosis

Background:

The expression of SMAD4, the central component of the transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signalling pathways, is lost in 50% of pancreatic cancers and is associated with a poor survival. Although the TGF-β pathway has been extensively studied and characterised in pancreatic cancer, there is very limited data on BMP signalling, a well-known tumour-suppressor pathway. BMP signalling can be lost not only at the level of SMAD4 but also at the level of BMP receptors (BMPRs), as has been described in colorectal cancer.

Methods:

We performed immunohistochemical analysis of the expression levels of BMP signalling components in pancreatic cancer and correlated these with survival. We also manipulated the activity of BMP signalling in vitro.

Results:

Reduced expression of BMPRIA is associated with a significantly worse survival, primarily in a subset of SMAD4-positive cancers. In vitro inactivation of SMAD4-dependent BMP signalling increases proliferation and invasion of pancreatic cancer cells, whereas inactivation of BMP signalling in SMAD4-negative cells does not change the proliferation and invasion or leads to an opposite effect.

Conclusion:

Our data suggest that BMPRIA expression is a good prognostic marker and that the BMP pathway is a potential target for future therapeutic interventions in pancreatic cancer.

DNA methylation of Smad4 promoter in gastric cancer in Xinjiang Kazak patients

AIM: To determine the relationship between methylation of the Smad4 promoter and the incidence of gastric cancer (GC) in Kazakh Chinese in Xinjiang Uygur Autonomous Region of China.

METHODS: Thirty patients with gastric cancer and 30 normal individuals were recruited from Kazak Autonomous Prefecture, an area with a high prevalence of gastric cancer. MassARRAY was used to detect Smad4 promoter methylation in samples taken from both GC patients and healthy controls.

RESULTS: The mean CpG methylation rate in GC was higher than that in normal gastric tissue (26.5% vs 21.7%). The mean methylation rates in CpG 3-4 and CpG 10-11 in GC were significantly higher than those in normal controls (19.1% vs 10.9%; 20.3% vs 11.5%, both P < 0.05).

CONCLUSION: The Smad4 promoter methylation status is correlated with the presence of GC in Kazakh Chinese. Changes in the methylation of CpG 3-4 and/or CpG 10-11 of the Smad4 gene may lead to the development of GC.

H. pylori induces the expression of Hath1 in gastric epithelial cells via interleukin-8/STAT3 phosphorylation while suppressing Hes1

Chronic gastritis associated with Helicobacter pylori is a leading cause of gastric intestinal metaplasia (IM), which arises from abnormal cell differentiation of the epithelium in the gastric mucosa. However, the mechanisms involved in H. pylori-mediated IM remain elusive. The aim of our study was to explore the effects and the underlying mechanisms of H. pylori on the abnormal expression of Hath1 and Sox2 and to reveal its relationship to the development of gastric IM. We found that Hath1 and Sox2 were overexpressed in gastric IM tissue. Hath1 expression was up-regulated, whereas Sox2 expression, which was independent of the CagA virulence factor, was down-regulated in gastric epithelial cells and coincided with increased IL-6 and IL-8 levels in the culture media. Stimulation with H. pylori-related cytokine IL-8, but not IL-6 or IL-1β, was induced by Hath1 expression in the gastric epithelial cells. Although IL-8 and IL-6 levels correlated with STAT3 (signal transducer and activator of transcription) phosphorylation before and after H. pylori eradication in the gastric mucosa, only the blocking of IL-8-induced STAT3 activation using AG490 or STAT3-targeting RNA interference altered Hath1 expression. Additionally, we found that H. pylori down-regulated Hes1, which is a direct downstream target gene of Notch signaling and a repressor of Hath1 expression. These findings suggest that H. pylori induced inflammation up-regulate Hath1 expression via interleukin-8/STAT3 (IL-8) phosphorylation while suppressing Hes1, which provides a novel molecular connection between a H. pylori infection and intestinal metaplasia.

CDX2 regulation by the RNA-binding protein MEX3A: impact on intestinal differentiation and stemness

The homeobox transcription factor CDX2 plays a crucial role in intestinal cell fate specification, both during normal development and in tumorigenic processes involving intestinal reprogramming. The CDX2 regulatory network is intricate, but it has not yet been fully uncovered. Through genome-wide screening of a 3D culture system, the RNA-binding protein MEX3A was identified as putatively involved in CDX2 regulation; therefore, its biological relevance was addressed by setting up cell-based assays together with expression studies in murine intestine. We demonstrate here that MEX3A has a repressive function by controlling CDX2 levels in gastric and colorectal cellular models. This is dependent on the interaction with a specific binding determinant present in CDX2 mRNA 3'untranslated region. We have further determined that MEX3A impairs intestinal differentiation and cellular polarization, affects cell cycle progression and promotes increased expression of intestinal stem cell markers, namely LGR5, BMI1 and MSI1. Finally, we show that MEX3A is expressed in mouse intestine, supporting an in vivo context for interaction with CDX2 and modulation of stem cell properties. Therefore, we describe a novel CDX2 post-transcriptional regulatory mechanism, through the RNA-binding protein MEX3A, with a major impact in intestinal differentiation, polarity and stemness, likely contributing to intestinal homeostasis and carcinogenesis.

Identification of the novel differentiation marker MS4A8B and its murine homolog MS4A8A in colonic epithelial cells lost during neoplastic transformation in human colon

The CD20-homolog Ms4a8a has recently been shown to be a marker for alternatively activated macrophages but its expression is not restricted to hematopoietic cells. Here, MS4A8A/MS4A8B expression was detected in differentiated intestinal epithelium in mouse and human, respectively. Interestingly, no MS4A8B expression was found in human colon carcinoma. Forced overexpression of MS4A8A in the murine colon carcinoma cell line CT26 led to a reduced proliferation and migration rate. In addition, MS4A8A-expressing CT26 cells displayed an increased resistance to hydrogen peroxide-induced apoptosis, which translated in an increased end weight of subcutaneous MS4A8A+ CT26 tumors. Gene profiling of MS4A8A+ CT26 cells revealed a significant regulation of 225 genes, most of them involved in cytoskeletal organization, apoptosis, proliferation, transcriptional regulation and metabolic processes. Thereby, the highest upregulated gene was the intestinal differentiation marker cytokeratin 20. In conclusion, we show that MS4A8A/MS4A8B is a novel differentiation marker of the intestinal epithelium that supports the maintenance of a physiological barrier function in the gut by modulating the transcriptome and by conferring an increased resistance to reactive oxygen species. The absence of MS4A8B in human colonic adenocarcinomas shown in this study might be a helpful tool to differentiate between healthy and neoplastic tissue.

Gastric Helicobacter infection induces iron deficiency in the INS-GAS mouse

There is increasing evidence from clinical and population studies for a role of H. pylori infection in the aetiology of iron deficiency. Rodent models of Helicobacter infection are helpful for investigating any causal links and mechanisms of iron deficiency in the host. The aim of this study was to investigate the effects of gastric Helicobacter infection on iron deficiency and host iron metabolism/transport gene expression in hypergastrinemic INS-GAS mice. INS-GAS mice were infected with Helicobacter felis for 3, 6 and 9 months. At post mortem, blood was taken for assessment of iron status and gastric mucosa for pathology, immunohistology and analysis of gene expression. Chronic Helicobacter infection of INS- GAS mice resulted in decreased serum iron, transferrin saturation and hypoferritinemia and increased Total iron binding capacity (TIBC). Decreased serum iron concentrations were associated with a concomitant reduction in the number of parietal cells, strengthening the association between hypochlorhydria and gastric Helicobacter-induced iron deficiency. Infection with H. felis for nine months was associated with decreased gastric expression of iron metabolism regulators hepcidin, Bmp4 and Bmp6 but increased expression of Ferroportin 1, the iron efflux protein, iron absorption genes such as Divalent metal transporter 1, Transferrin receptor 1 and also Lcn2 a siderophore-binding protein. The INS-GAS mouse is therefore a useful model for studying Helicobacter-induced iron deficiency. Furthermore, the marked changes in expression of gastric iron transporters following Helicobacter infection may be relevant to the more rapid development of carcinogenesis in the Helicobacter infected INS-GAS model.

Gastric intestinal metaplasia revisited: function and regulation of CDX2

Intestinal metaplasia of the stomach is a preneoplastic lesion that appears following Helicobacter pylori infection and confers increased risk for gastric cancer development. However, the molecular networks connecting infection to lesion formation and the cellular origin of this lesion remain largely unknown. A more comprehensive understanding of how intestinal metaplasia arises and is maintained will be a major breakthrough towards developing novel therapeutic interventions. Furthermore, after ascertaining the pivotal role of CDX2 in establishing and maintaining intestinal metaplasia, it becomes important to decipher the upstream molecular pathways leading to its ectopic expression. Here, we review the pathophysiology of intestinal metaplasia in the context of the molecular network involved in its establishment and maintenance, with emphasis on CDX2 function and regulation.

Helicobacter pylori and the BMP pathway regulate CDX2 and SOX2 expression in gastric cells

Helicobacter pylori infection is the main risk factor for intestinal metaplasia (IM) and gastric cancer development. IM is a pre-neoplastic lesion, induced by the transcription factor CDX2, where the gastric mucosa is converted to an intestinal phenotype. We previously demonstrated that key elements of the bone morphogenetic protein (BMP) pathway co-localize with CDX2 in IM and upregulate CDX2 expression in gastric cell lines. These observations, together with the hypothesis that CDX2 could be repressed by SOX2, led us to test whether H. pylori, through BMPs, SOX2 and CDX2 could participate in a molecular network critical for the development of IM. AGS cells with and without SMAD4 knock-down were co-cultured with H. pylori or BMP2 to assess the expression of BMP pathway members as well as CDX2 and SOX2 by qPCR and western blot. Proximity ligation assay (PLA) was also performed to evaluate SMAD proteins interaction. Immunohistochemistry and western blot were performed in gastric samples from mice infected with Helicobacter spp. to measure Smad4, pSmad1/5/8, Cdx2 and Sox2 expression in vivo. Increased expression and activity of the BMP pathway accompanied by CDX2 upregulation and SOX2 downregulation were observed in AGS cells co-cultured with H. pylori or BMP2. These effects were impaired by downregulation of the BMP pathway. Finally, infected mice present BMP pathway upregulation, focal Cdx2 expression and decreased Sox2. These results provide a novel link between H. pylori infection and the BMP pathway in the regulation of intestinal and gastric-specific genes that might be relevant for gastric IM.

Inflammation and Barrett's carcinogenesis

Barrett's esophagus (BE) is one of the most common premalignant lesions in which normal squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium. Esophageal adenocarcinoma (EA) develops through progression from BE to low- and high-grade dysplasia (LGD/HGD) and to adenocarcinoma. It is widely accepted that inflammation can increase cancer risk, promoting tumor progression. Therefore, inflammation is regarded as the seventh hallmark of cancer. In recent years, the inflammation-cancer connection of Barrett's carcinogenesis has been intensively studied, unraveling genetic abnormalities. Besides genetic alterations, inflammation is also epigenetically linked to loss of protein expression through transcriptional silencing via promoter methylation. Key mediators linking inflammation and Barrett's carcinogenesis include reactive oxygen species (ROS), NFκB, inflammatory cytokines, prostaglandins, and specific microRNAs (miRNAs). Therefore, the decipherment of molecular pathways that contain these and novel inflammatory key mediators is of major importance for diagnosis, therapy, and prognosis. The detailed elucidation of the signaling molecules involved in Barrett's carcinogenesis will be important for the development of pharmaceutical inhibitors. We herein give an overview of the current knowledge of the inflammation-mediated genetic and epigenetic alterations involved in Barrett's carcinogenesis. We highlight the role of oxidative stress and deregulated DNA damage checkpoints besides the NFκB pathway.

Different subtypes of intraductal papillary mucinous neoplasm in the pancreas have distinct pathways to pancreatic cancer progression

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN) is recognized as a precursor lesion to pancreatic cancer, a unique pathological entity. IPMN has subtypes with different clinical characteristics. However, the molecular mechanisms of cancer progression from IPMN remain largely unknown. In this study we examined the differences in genetic alteration(s) among the IPMN subtypes.

METHODS

Surgically resected IPMNs (n = 25) were classified into four subtypes by hematoxylin and eosin (H&E) and mucin immunostaining. Mutations in KRAS, BRAF, and PIK3CA genes and expression of CDKN2A, TP53, SMAD4, phospho-ERK, and phospho-SMAD1/5/8 proteins were examined.

RESULTS

There were 11 gastric, 11 intestinal, one pancreatobiliary, and two oncocytic types in this study. We then compared the two major subtypes, gastric-type and intestinal-type IPMN. Gastric-type IPMN showed a significantly higher incidence of KRAS mutations (9/11, 81.8%) compared with intestinal type (3/11, 27.3%; p < 0.05), although the intestinal type showed a higher grade of dysplasia than gastric type (p < 0.01). All cases with KRAS mutations showed phospho-ERK immunostaining. In contrast, intestinal type (9/11, 81.8%) showed more frequent SMAD1/5/8 phosphorylation compared with gastric-type IPMN (3/11, 27.3%; p < 0.05%).

CONCLUSIONS

There may be distinct mechanisms of pancreatic cancer progression in the different subtypes of IPMN. In particular, KRAS mutation and bone morphogenetic protein-SMAD signaling status may be crucial diverging steps for the two representative pathways to pancreatic cancer in IPMN patients.

Current and emerging approaches to define intestinal epithelium-specific transcriptional networks

Upon developmental or environmental cues, the composition of transcription factors in a transcriptional regulatory network is deeply implicated in controlling the signature of the gene expression and thereby specifies the cell or tissue type. Novel methods including ChIP-chip and ChIP-Seq have been applied to analyze known transcription factors and their interacting regulatory DNA elements in the intestine. The intestine is an example of a dynamic tissue where stem cells in the crypt proliferate and undergo a differentiation process toward the villus. During this differentiation process, specific regulatory networks of transcription factors are activated to target specific genes, which determine the intestinal cell fate. The expanding genomewide mapping of transcription factor binding sites and construction of transcriptional regulatory networks provide new insight into how intestinal differentiation occurs. This review summarizes the current overview of the transcriptional regulatory networks driving epithelial differentiation in adult intestine. The novel technologies that have been implied to study these networks are presented and their prospects for implications in future research are also addressed.

Metastatic function of BMP-2 in gastric cancer cells: the role of PI3K/AKT, MAPK, the NF-κB pathway, and MMP-9 expression

Bone morphogenetic proteins (BMPs) have been implicated in tumorigenesis and metastatic progression in various types of cancer cells, but the role and cellular mechanism in the invasive phenotype of gastric cancer cells is not known. Herein, we determined the roles of phosphoinositide 3-kinase (PI3K)/AKT, extracellular signal-regulated protein kinase (ERK), nuclear factor (NF)-κB, and matrix metalloproteinase (MMP) expression in BMP-2-mediated metastatic function in gastric cancer. We found that stimulation of BMP-2 in gastric cancer cells enhanced the phosphorylation of AKT and ERK. Accompanying activation of AKT and ERK kinase, BMP-2 also enhanced phosphorylation/degradation of IκBα and the nuclear translocation/activation of NF-κB. Interestingly, blockade of PI3K/AKT and ERK signaling using LY294002 and PD98059, respectively, significantly inhibited BMP-2-induced motility and invasiveness in association with the activation of NF-κB. Furthermore, BMP-2-induced MMP-9 expression and enzymatic activity was also significantly blocked by treatment with PI3K/AKT, ERK, or NF-κB inhibitors. Immunohistochemistry staining of 178 gastric tumor biopsies indicated that expression of BMP-2 and MMP-9 had a significant positive correlation with lymph node metastasis and a poor prognosis. These results indicate that the BMP-2 signaling pathway enhances tumor metastasis in gastric cancer by sequential activation of the PI3K/AKT or MAPK pathway followed by the induction of NF-κB and MMP-9 activity, indicating that BMP-2 has the potential to be a therapeutic molecular target to decrease metastasis.

HNF1α and CDX2 transcriptional factors bind to cadherin-17 (CDH17) gene promoter and modulate its expression in hepatocellular carcinoma

Cadherin-17 (CDH17) belongs to the cell adhesion cadherin family with a prominent role in tumorigenesis. It is highly expressed in human hepatocellular carcinoma (HCC) and is proposed to be a biomarker and therapeutic molecule for liver malignancy. The present study aims to identify the transcription factors which interact and regulate CDH17 promoter activity that might contribute to the up-regulation of CDH17 gene in human HCC. A 1-kb upstream sequence of CDH17 gene was cloned and the promoter activity was studied by luciferase reporter assay. By bioinformatics analysis, deletion and mutation assays, and chromatin immunoprecipitation studies, we identified hepatic nuclear factor 1α (HNF1α) and caudal-related homeobox 2 (CDX2) binding sites at the proximal promoter region which modulate the CDH17 promoter activities in two HCC cell lines (Hep3B and MHCC97L). A consistent down-regulation of CDH17 and the two transcriptional activators (HNF1α and CDX2) expression was found in the liver of mouse during development, as well as in human liver cancer cells with less metastatic potential. Suppression of HNF1α and CDX2 expression by small interfering RNA (siRNA) significantly down-regulated expressions of CDH17 and its downstream target cyclin D1 and the viability of HCC cells in vitro. In summary, we identified the minimal promoter region of CDH17 that is regulated by HNF1α and CDX2 transcriptional factors. The present findings enhance our understanding on the regulatory mechanisms of CDH17 oncogene in HCC, and may shed new insights into targeting CDH17 expression as potential therapeutic intervention for cancer treatment.

Pinin modulates expression of an intestinal homeobox gene, Cdx2, and plays an essential role for small intestinal morphogenesis

Pinin (Pnn), a nuclear speckle-associated protein, has been shown to function in maintenance of epithelial integrity through altering expression of several key adhesion molecules. Here we demonstrate that Pnn plays a crucial role in small intestinal development by influencing expression of an intestinal homeobox gene, Cdx2. Conditional inactivation of Pnn within intestinal epithelia resulted in significant downregulation of a caudal type homeobox gene, Cdx2, leading to obvious villus dysmorphogenesis and severely disrupted epithelial differentiation. Additionally, in Pnn-deficient small intestine, we observed upregulated Tcf/Lef reporter activity, as well as misregulated expression/distribution of beta-catenin and Tcf4. Since regulation of Cdx gene expression has been closely linked to Wnt/beta-catenin signaling activity, we explored the possibility of Pnn's interaction with beta-catenin, a major effector of the canonical Wnt signaling pathway. Co-immunoprecipitation assays revealed that Pnn, together with its interaction partner CtBP2, a transcriptional co-repressor, was in a complex with beta-catenin. Moreover, both of these proteins were found to be recruited to the proximal promoter area of Cdx2. Taken together, our results suggest that Pnn is essential for tight regulation of Wnt signaling and Cdx2 expression during small intestinal development.

Pathophysiology of intestinal metaplasia of the stomach: emphasis on CDX2 regulation

IM (intestinal metaplasia) of the stomach is a pre-neoplastic lesion that usually follows Helicobacter pylori infection and that confers increased risk for gastric cancer development. After setting the role played by CDX2 (Caudal-type homeobox 2) in the establishment of gastric IM, it became of foremost importance to unravel the regulatory mechanisms behind its de novo expression in the stomach. In the present paper, we review the basic pathology of gastric IM as well as the current knowledge on molecular pathways involved in CDX2 regulation in the gastric context.

Cdx genes, inflammation, and the pathogenesis of intestinal metaplasia

Intestinal metaplasia (IM) is a biologically interesting and clinically relevant condition in which one differentiated type of epithelium is replaced by another that is morphologically similar to normal intestinal epithelium. Two classic examples of this are gastric IM and Barrett's esophagus (BE). In both, a chronic inflammatory microenvironment, provoked either by Helicobacter pylori infection of the stomach or acid and bile reflux into the esophagus, precedes the metaplasia. The Caudal-related homeodomain transcription factors Cdx1 and Cdx2 are critical regulators of the normal intestinal epithelial cell phenotype. Ectopic expression of Cdx1 and Cdx2 occurs in both gastric IM as well as in BE. This expression precedes the onset of the metaplasia and implies a causal role for these factors in this process. We review the observations regarding the role of chronic inflammation and the Cdx transcription factors in the pathogenesis of gastric IM and BE.

BMP4 induction of trophoblast from mouse embryonic stem cells in defined culture conditions on laminin

Because mouse embryonic stem cells (mESCs) do not contribute to the formation of extraembryonic placenta when they are injected into blastocysts, it is believed that mESCs do not differentiate into trophoblast whereas human embryonic stem cells (hESCs) can express trophoblast markers when exposed to bone morphogenetic protein 4 (BMP4) in vitro. To test whether mESCs have the potential to differentiate into trophoblast, we assessed the effect of BMP4 on mESCs in a defined monolayer culture condition. The expression of trophoblast-specific transcription factors such as Cdx2, Dlx3, Esx1, Gata3, Hand1, Mash2, and Plx1 was specifically upregulated in the BMP4-treated differentiated cells, and these cells expressed trophoblast markers. These results suggest that BMP4 treatment in defined culture conditions enabled mESCs to differentiate into trophoblast. This differentiation was inhibited by serum or leukemia inhibitory factor, which are generally used for mESC culture. In addition, we studied the mechanism underlying BMP4-directed mESC differentiation into trophoblast. Our results showed that BMP4 activates the Smad pathway in mESCs inducing Cdx2 expression, which plays a crucial role in trophoblast differentiation, through the binding of Smad protein to the Cdx2 genomic enhancer sequence. Our findings imply that there is a common molecular mechanism underlying hESC and mESC differentiation into trophoblast.

Cdx genes, inflammation and the pathogenesis of Barrett's metaplasia

Metaplasia is the conversion of one cell or tissue type to another and can predispose patients to neoplasia. Perhaps one of the best-known examples of metaplasia is Barrett's metaplasia (BM), a pathological condition in which the distal oesophageal epithelium switches from stratified squamous to intestinal-type columnar epithelium. BM predisposes to oesophageal adenocarcinoma and is the consequence of long-term acid bile reflux. The incidence of BM and oesophageal adenocarcinoma has risen dramatically in recent years. A key event in the pathogenesis of BM is the induction of oesophageal CDX2 expression. Importantly, recent data reveal the molecular mechanisms that link inflammation in the development of Barrett's metaplasia, CDX2 and the progression to cancer. This review highlights the relationship between inflammation, metaplasia and carcinogenesis.

Epithelial metaplasia: adult stem cell reprogramming and (pre)neoplastic transformation mediated by inflammation?

Throughout adult life, new developmental commitment of adult stem cells causes metaplastic conversions to occur frequently in some organs. These reversible epithelial replacements are almost always observed in association with chronic inflammation and persistent irritation. Although metaplasia is not synonymous with dysplasia, clinical surveillance has demonstrated that these adaptive processes have an increased susceptibility to evolve into cancer. We propose that cytokines and other soluble factors released by both epithelial and inflammatory cells might alter the transcription-factor expression profile of stem cells and lead to the development of metaplasia. Furthermore, inflammatory mediators might also promote the malignant transformation of epithelial metaplasia by inducing genetic and epigenetic changes and by preventing the immune system from mounting an efficient anti-tumour immune response. A better understanding of the molecular mechanisms leading to metaplasia might help in the design of new therapies for neoplastic and degenerative diseases.

Role of Smad4 in cancer invasion and metastasis

Transforming growth factor beta (TGF-β) is a ubiquitous and essential regulator of cellular and physiologic processes including proliferation, differentiation, migration, cell survival, angiogenesis and immunosurveillance. The tumor suppressor gene Smad4 (DPC4) is the central intracellular mediator of transforming growth factor-β-Smad(TGF-β-Smad) signaling, which is a key pathway in cancer invasion and metastasis. This review focuses on the mechanisms whereby the Smads are modified and regulated, and summarizes current views on the role of Smad4 in tumorigenesis, with emphasis on cancer invasion and metastasis.

Juvenile polyps have gastric differentiation with MUC5AC expression and downregulation of CDX2 and SMAD4

CDX2 is a homeobox transcription factor that works as a master gene in intestinal differentiation, both in the colon and in aberrant locations such as intestinal metaplasia (IM) of the stomach. Transgenic mice with Cdx2 expression in the stomach develop IM and Cdx2(+/-) mice develop hamartomatous polyps in the colon presenting gastric differentiation. We previously observed regulation of CDX2 by the BMP/SMAD pathway in the gastric context. Here, we hypothesized that juvenile polyps, which are hamartomatous polyps caused by mutations in members of the BMP/SMAD pathway, might recapitulate the gastric differentiation observed in Cdx2(+/-) mice due to SMAD4 and CDX2 downregulation. We characterized SMAD4 and CDX2 expression in a series of 18 solitary juvenile polyps and 2 polyps from juvenile polyposis (JP) patients, one with a germline SMAD4 mutation and one with a germline BMPRIA mutation, as well as the expression of an intestinal differentiation marker, MUC2 (by immunohistochemistry and in situ hybridization), and gastric differentiation markers, MUC5AC and MUC6 (by immunohistochemistry). We observed that juvenile polyps have a heterogeneous expression of CDX2, MUC2 and SMAD4, with negative areas, and 15 of the 18 solitary polyps and the JP case with SMAD4 mutation exhibit de novo expression of MUC5AC but not MUC6. In conclusion, juvenile polyps have gastric transdifferentiation associated with downregulation of CDX2 and SMAD4, lending support to the role of the BMP/SMAD pathway in CDX2 regulation.

Differential gene expression in normal esophagus and Barrett's esophagus

PURPOSE

As the premalignant lesion of human esophageal adenocarcinoma (EAC), Barrett's esophagus (BE) is characterized by intestinal metaplasia in the normal esophagus (NE). Gene expression profiling with microarray and serial analysis of gene expression (SAGE) may help us understand the potential molecular mechanism of human BE.

METHODS

We analyzed three microarray datasets (two cDNA arrays and one oligonucleotide array) and one SAGE dataset with statistical tools, significance analysis of microarrays (SAM) and SAGE(Poisson), to identify individual genes differentially expressed in BE. Gene set enrichment analysis (GSEA) was used to identify a priori defined sets of genes that were differentially expressed. These gene sets were grouped according to either certain signaling pathways (GSEA curated), or the presence of consensus binding sequences of known transcription factors (GSEA motif). Immunohistochemical staining (IHC) was used to validate differential gene expression.

RESULTS

Both SAM and SAGE(Poisson) identified 68 differentially expressed genes (55 BE genes and 13 NE genes) with an arbitrary cutoff ratio (> or =4-fold). With IHC on matched pairs of NE and BE tissues from 6 patients, these genes were grouped into 6 categories: category I (25 genes only expressed in BE), category II (5 genes only expressed in NE), category III (8 genes expressed more in BE than in NE), and category IV (2 genes expressed more in NE than in BE). Differential expression of the remaining genes was not confirmed by IHC either due to false discovery (category V), or lack of proper antibodies (category VI). Besides individual genes, the TGFbeta pathway and several transcription factors (CDX2, HNF1, and HNF4) were identified by GSEA as enriched pathways and motifs in BE. Apart from 9 target genes known to be up-regulated in BE, IHC staining confirmed up-regulation of 19 additional CDX1 and CDX2 target genes in BE.

CONCLUSION

Our data suggested an important role of CDX1 and CDX2 in the development of BE. The IHC-confirmed gene list will lead to future studies on the molecular mechanism of BE.