The role of Cdx2 in Barrett's metaplasia. Biochem Soc Trans. 2010;38:364-369. [PMID: 20298184 DOI: 10.1042/BST0380364]

Biologically targeted discovery-replication scan identifies G×G interaction in relation to risk of Barrett's esophagus and esophageal adenocarcinoma

Inherited genetics represents an important contributor to risk of esophageal adenocarcinoma (EAC), and its precursor Barrett's esophagus (BE). Genome-wide association studies have identified ∼30 susceptibility variants for BE/EAC, yet genetic interactions remain unexamined. To address challenges in large-scale G×G scans, we combined knowledge-guided filtering and machine learning approaches, focusing on genes with (1) known/plausible links to BE/EAC pathogenesis (n = 493) or (2) prior evidence of biological interactions (n = 4,196). Approximately 75 × 106 SNP×SNP interactions were screened via hierarchical group lasso (glinternet) using BEACON GWAS data. The top ∼2,000 interactions retained in each scan were prioritized using p values from single logistic models. Identical scans were repeated among males only (78%), with two independent GWAS datasets used for replication. In overall and male-specific primary replications, 11 of 187 and 20 of 191 interactions satisfied p < 0.05, respectively. The strongest evidence for secondary replication was for rs17744726×rs3217992 among males, with consistent directionality across all cohorts (Pmeta = 2.19 × 10-8); rs3217992 "T" was associated with reduced risk only in individuals homozygous for rs17744726 "G." Rs3217992 maps to the CDKN2B 3' UTR and reportedly disrupts microRNA-mediated repression. Rs17744726 maps to an intronic enhancer region in BLK. Through in silico prioritization and experimental validation, we identified a nearby proxy variant (rs4841556) as a functional modulator of enhancer activity. Enhancer-gene mapping and eQTLs implicated BLK and FAM167A as targets. The first systematic G×G investigation in BE/EAC, this study uncovers differential risk associations for CDKN2B variation by BLK genotype, suggesting novel biological dependency between two risk loci encoding key mediators of tumor suppression and inflammation.

Ectopic expression of HNF4α in Het1A cells induces an invasive phenotype

Barrett's oesophagus (BO) is a pathological condition in which the squamous epithelium of the distal oesophagus is replaced by an intestinal-like columnar epithelium originating from the gastric cardia. Several somatic mutations contribute to the intestinal-like metaplasia. Once these have occurred in a single cell, it will be unable to expand further unless the altered cell can colonise the surrounding squamous epithelium of the oesophagus. The mechanisms by which this happens are still unknown. Here we have established an in vitro system for examining the competitive behaviour of two epithelia. We find that when an oesophageal epithelium model (Het1A cells) is confronted by an intestinal epithelium model (Caco-2 cells), the intestinal cells expand into the oesophageal domain. In this case the boundary involves overgrowth by the Caco-2 cells and the formation of isolated colonies. Two key transcription factors, normally involved in intestinal development, HNF4α and CDX2, are both expressed in BO. We examined the competitive ability of Het1A cells stably expressing HNF4α or CDX2 and placed in confrontation with unmodified Het1A cells. The key result is that stable expression of HNF4α, but not CDX2, increased the ability of the cells to migrate and push into the unmodified Het1A domain. In this situation the boundary between the cell types is a sharp one, as is normally seen in BO. The experiments were conducted using a variety of extracellular substrates, which all tended to increase the cell migration compared to uncoated plastic. These data provide evidence that HNF4α expression could have a potential role in the competitive spread of BO into the oesophagus as HNF4α increases the ability of cells to invade into the adjacent stratified squamous epithelium, thus enabling a single mutant cell eventually to generate a macroscopic patch of metaplasia.

CDX-2 Expression in Esophageal Biopsies Without Goblet Cell Intestinal Metaplasia May Be Predictive of Barrett's Esophagus

BACKGROUND

CDX-2 is a nuclear homeobox transcription factor not normally expressed in esophageal and gastric epithelia, reported to highlight intestinal metaplasia (IM) in the esophagus. Pathological absence of goblet cells at initial screening via hematoxylin and eosin (HE) and alcian blue (AB) staining results in patient exclusion from surveillance programs.

AIMS

This study aimed to determine whether non-goblet cell IM, as defined by CDX-2 positivity, can be considered to be a precursor to Barrett's esophagus (BE).

METHODS

This study received IRB approval (17,284). Patients with gastroesophageal reflux disease (n = 181) who underwent upper-gastrointestinal endoscopy with biopsies of the distal esophagus to rule out BE using HE/AB staining and CDX-2 immunostaining were followed for 3 years. Initial and follow-up staining results were evaluated for age/sex.

RESULTS

Differences between development of goblet cell IM in CDX-2-negative and CDX-2-positive groups were evaluated. A Kaplan-Meier curve showed that, out of the 134 patients initially positive for CDX-2, 25 (18.7%) had developed goblet cell IM after 2 years and 106 (79.1%) after 3 years. Conversely, of the 47 patients initially negative for CDX-2, 8 (17.9%) developed goblet cell IM after 24 months and only 11 (23.8%) after 40 to 45 months (P = .049; age-adjusted Cox proportional hazard regression model).

CONCLUSION

In cases that are initially AB negative and CDX-2 positive, CDX-2 was demonstrated to have a potential prognostic utility for early detection of progression to BE. CDX-2 expression is significantly predictive for risk of goblet cell IM development 40 to 45 months after initial biopsy.

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.

Lineage Plasticity in Cancer Progression and Treatment

Historically, it has been widely presumed that differentiated cells are determined during development and become irreversibly committed to their designated fates. In certain circumstances, however, differentiated cells can display plasticity by changing their identity, either by dedifferentiation to a progenitor-like state or by transdifferentiation to an alternative differentiated cell type. Such cellular plasticity can be triggered by physiological or oncogenic stress, or it can be experimentally induced through cellular reprogramming. Notably, physiological stresses that promote plasticity, such as severe tissue damage, inflammation, or senescence, also represent hallmarks of cancer. Furthermore, key drivers of cellular plasticity include major oncogenic and tumor suppressor pathways and can be exacerbated by drug treatment. Thus, plasticity may help cancer cells evade detection and treatment. We propose that cancer can be considered as a disease of excess plasticity, a notion that has important implications for intervention and treatment.

The multipotency-to-commitment transition in Caenorhabditis elegans-implications for reprogramming from cells to organs

In animal embryos, cells transition from a multipotential state, with the capacity to adopt multiple fates, into an irreversible, committed state of differentiation. This multipotency-to-commitment transition (MCT) is evident from experiments in which cell fate is reprogrammed by transcription factors for cell type-specific differentiation, as has been observed extensively in Caenorhabditis elegans. Although factors that direct differentiation into each of the three germ layer types cannot generally reprogram cells after the MCT in this animal, transcription factors for endoderm development are able to do so in multiple differentiated cell types. In one case, these factors can redirect the development of an entire organ in the process of "transorganogenesis". Natural transdifferentiation also occurs in a small number of differentiated cells during normal C. elegans development. We review these reprogramming and transdifferentiation events, highlighting the cellular and developmental contexts in which they occur, and discuss common themes underlying direct cell lineage reprogramming. Although certain aspects may be unique to the model system, growing evidence suggests that some mechanisms are evolutionarily conserved and may shed light on cellular plasticity and disease in humans.

Expression of SOX9 and CDX2 in nongoblet columnar-lined esophagus predicts the detection of Barrett's esophagus during follow-up

The diagnosis of Barrett's esophagus in the United States requires both endoscopically evident columnar-lined esophagus and the presence of goblet cells by histology. Currently, there is no consensus on how patients with nongoblet columnar-lined esophagus should be followed. In this study, we investigated whether biomarkers can be used to predict the detection of goblet cells in follow-up biopsies. Patients with nongoblet columnar-lined esophagus were identified. In 13 of these cases, goblet cells were detected in subsequent follow-up endoscopic biopsies (Barrett's group). Additionally, 26 cases that remained negative for goblet cells in follow-up biopsies served as controls. Immunohistochemistry for CDX2, SOX9, BMP4, SHH, and MUC2 was performed on the initial biopsies and graded independently by at least two pathologists in a masked manner. CDX2 was positive in the nongoblet columnar epithelium of 7/13 cases in the Barrett's group and in 4/26 controls (sensitivity 54%, specificity of 85%, odds ratio (OR) 6.4). Strong and diffuse immunoreactivity for SOX9 was detected in 10/13 cases in the Barrett's group and in 1/26 controls (sensitivity 77%, specificity 96%, OR 83.3). Combining CDX2 and SOX9 as a panel increased sensitivity to 85%, although the specificity decreased to 85% (OR 30.3). SHH, BMP4, and MUC2 expression showed no significant difference between the Barrett's and control groups. In patients with nongoblet columnar-lined esophagus, SOX9 and CDX2 may be useful in identifying a subset of patients who have a higher risk of being diagnosed for Barrett's esophagus (developing goblet cells) and need closer follow-up.

The clinical perspectives of CDX2 expression in colorectal cancer: a qualitative systematic review

INTRODUCTION

Homeobox genes are often deregulated in cancer. They can have both oncogenic and tumor-suppressing potential. The Caudal-related homeobox transcription factor 2 (CDX2) is an intestine-specific transcription factor. It is implicated in differentiation, proliferation, cell-adhesion, and migration. CDX2 has been proposed as a tumor suppressor in colorectal cancer but its role is still controversial. This systematic review were undertaken in order to clarify CDX2s role in colorectal cancer.

METHODS

A literature search was performed in the MEDLINE database from 1966 to February 2014. Only studies in which all or a part of the experimental design were performed on human colorectal cancer tissue were included. Thus, studies solely performed in cell-lines or animal models were excluded.

RESULTS

Fifty-two articles of relevance were identified. CDX2 expression was rarely lost in colorectal cancers, however the expression pattern may often be heterogeneous within the tumor and can be selectively down regulated at the invasive front and in tumor buddings. Loss of CDX2 expression is probably correlated to tumor grade, stage, right-sided tumor location, MMR-deficiency, CIMP, and BRAF mutations. The CDX2 gene is rarely mutated but the locus harboring the gene is often amplified and may suggest CDX2 as a linage-survival oncogene. CDX2 might be implicated in cell proliferation and migration through cross-talk with the Wnt-signaling pathway, tumor-stroma proteins, and inflammatory cytokines.

CONCLUSION

A clear role for CDX2 expression in colorectal cancer remains to be elucidated, and it might differ in relation to the underlying molecular pathways leading to the cancer formation.

Hacking cell differentiation: transcriptional rerouting in reprogramming, lineage infidelity and metaplasia

Initiating neoplastic cell transformation events are of paramount importance for the comprehension of regeneration and vanguard oncogenic processes but are difficult to characterize and frequently clinically overlooked. In epithelia, pre-neoplastic transformation stages are often distinguished by the appearance of phenotypic features of another differentiated tissue, termed metaplasia. In haemato/lymphopoietic malignancies, cell lineage ambiguity is increasingly recorded. Both, metaplasia and biphenotypic leukaemia/lymphoma represent examples of dysregulated cell differentiation that reflect a history of trans-differentiation and/or epigenetic reprogramming. Here we compare the similarity between molecular events of experimental cell trans-differentiation as an emerging therapeutic concept, with lineage confusion, as in metaplasia and dysplasia forecasting tumour development.

Liver-intestine-cadherin is a sensitive marker of intestinal differentiation during Barrett's carcinogenesis

BACKGROUND

Histopathologic differentiation between the stages of Barrett's carcinogenesis is often challenging. Liver-intestine (LI)-cadherin, an intestine-specific marker, is involved in intestinal metaplasia development in gastric and colon cancers and could be of value in diagnosis and differentiation.

AIMS

To examine the expression of LI-cadherin in the sequence of Barrett's carcinogenesis and to evaluate its association with clinicopathological data.

METHODS

LI-cadherin expression was immunohistologically investigated, by use of anti-CDH17 antibody, in gastric mucosa (GM) biopsies taken from the cardia (n = 9), in Barrett's esophagus (BE) without intraepithelial neoplasia (without IEN) (n = 9) and BE with low-grade IEN (n = 11), and in esophageal adenocarcinoma (ADC) (n = 13).

RESULTS

The immunoreactivity score was highest in adenocarcinoma (mean IRS = 4.0), and dropped gradually from BE with IEN and BE without IEN (mean IRS = 2.0) to cardia mucosa (IRS = 0). Similarly, the intensity of staining and the percentage of positive cells increased during the sequential stages of BE carcinogenesis. Comparative analysis showed that LI-cadherin expression was significantly different between cardiac epithelium and ADC. Also, percentage of positive cells in GM was significantly different from that in BE with IEN. LI-cadherin IRS was lower for tumors with poor differentiation than for moderately differentiated tumors, but the difference was not statistically significant.

CONCLUSIONS

LI-cadherin is a sensitive marker of intestinal metaplasia and can be helpful for early histologic diagnosis of Barrett's esophagus; it is, however, not significantly different between BE with and without IEN, and cannot be used to distinguish between these.

Barrett's esophagus and esophageal cancer: an overview

Although esophageal cancer (EC) is the eighth most common cancer in several European countries, it is one of deadliest worldwide. The most frequent predisposing factor implicated in its development is Barrett's esophagus (BE), an acquired metaplastic transformation of the esophageal lining cells from normal squamous epithelium into specialised or intestinal-like columnar epithelium. The major risk factor for BE is gastroesophageal reflux disease. Although BE is in itself a benign and often asymptomatic disorder, its clinical importance stems from the recognition that it represents the main precursor lesion for the development of esophageal adenocarcinoma (AC), a tumor that is rapidly increasing especially in developed countries and is associated with a low survival rate. This paper provides an overview of the epidemiology and natural history of BE as well as of the possible pathogenetic mechanisms underlying the development of BE and its progressive transition to AC. New diagnostic tests are described, recommendations for screening and surveillance are provided and surgical and ablative procedures to treat dysplastic lesions and early neoplasia are discussed. Claimed chemopreventive agents and biomarkers that in the near future may help identify people with a higher risk of EC are also considered.

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.

Study of FoxA pioneer factor at silent genes reveals Rfx-repressed enhancer at Cdx2 and a potential indicator of esophageal adenocarcinoma development

Understanding how silent genes can be competent for activation provides insight into development as well as cellular reprogramming and pathogenesis. We performed genomic location analysis of the pioneer transcription factor FoxA in the adult mouse liver and found that about one-third of the FoxA bound sites are near silent genes, including genes without detectable RNA polymerase II. Virtually all of the FoxA-bound silent sites are within conserved sequences, suggesting possible function. Such sites are enriched in motifs for transcriptional repressors, including for Rfx1 and type II nuclear hormone receptors. We found one such target site at a cryptic “shadow” enhancer 7 kilobases (kb) downstream of the Cdx2 gene, where Rfx1 restricts transcriptional activation by FoxA. The Cdx2 shadow enhancer exhibits a subset of regulatory properties of the upstream Cdx2 promoter region. While Cdx2 is ectopically induced in the early metaplastic condition of Barrett's esophagus, its expression is not necessarily present in progressive Barrett's with dysplasia or adenocarcinoma. By contrast, we find that Rfx1 expression in the esophageal epithelium becomes gradually extinguished during progression to cancer, i.e, expression of Rfx1 decreased markedly in dysplasia and adenocarcinoma. We propose that this decreased expression of Rfx1 could be an indicator of progression from Barrett's esophagus to adenocarcinoma and that similar analyses of other transcription factors bound to silent genes can reveal unanticipated regulatory insights into oncogenic progression and cellular reprogramming.

FoxA transcriptional regulatory proteins are “pioneer factors” that engage silent genes, helping to endow the competence for activation. About a third of the DNA sites we found to be occupied by FoxA in the adult liver are at genes that are silent. Analysis of transcription factor binding motifs near the FoxA sites at silent genes revealed a co-occurrence of motifs for the transcriptional repressors Rfx1 and type II nuclear hormone receptors (NHR-II). Further analysis of one such region downstream of the Cdx2 gene shows that it is a cryptic enhancer, in that it functions poorly unless Rfx1 or NHR-II binding is prevented, in which case FoxA1 promotes enhancer activity. Cdx2 encodes a transcription factor that promotes intestinal differentiation; ectopic expression of Cdx2 in the esophagus can help promote metaplasia and cancer. By screening numerous staged samples of human tissues, we show that Rfx1 expression is extinguished during the progression to esophageal adenocarcinoma and thus may serve as a marker of cancer progression. These studies exemplify how the analysis of pioneer factors bound to silent genes can reveal a basis for the competence of cells to deregulate gene expression and undergo transitions to cancer.

Significance of expression of Sox2 and Cdx2 in gastric intestinal metaplasia

AIM: To investigate the significance of expression of sex determining region Y-box 2 (Sox2) and caudal type homeobox transcription factor 2 (Cdx2) in gastric intestinal metaplasia (IM).

METHODS: The expression of SOX2 and CDX2 proteins in 80 paraffin-embedded specimens of gastritis and mild/moderate/severe IM was detected by immunohistochemistry. The mRNA levels of Sox2 and Cdx2 in 40 endoscopic biopsy specimens of gastritis and mild/moderate/severe IM were quantified by real-time Q-PCR.

RESULTS: Both SOX2 and CDX2 proteins were located in the nuclei of normal gastric and normal intestinal epithelial cells. The positive rates of SOX2 and CDX2 protein expression in gastritis and mild/moderate/severe IM were 94.4% and 5.6%, 75.0% and 50.0%, 23.5% and 85.7%, and 9.5% and 90.5%, respectively (all P < 0.05). The relative expression levels of Sox2 and Cdx2 mRNAs in gastritis and mild/moderate/severe IM were 0.5778 ± 0.0778 and 0.0517 ± 0.0218, 0.1496 ± 0.0384 and 0.1402 ± 0.0300, and 0.1131 ± 0.0384 and 0.3453 ± 0.0537, respectively (all P < 0.05). The levels of Sox2 transcripts decreased but those of Cdx2 transcripts increased with the progression of IM. There is an inverse correlation between the expression levels of Sox2 and Cdx2 (r < 0).

CONCLUSION: Down-regulation of Sox2 and ectopic expression of Cdx2 were found in the progression of gastric IM.