Aberrant expression of CDX2 in the gastric mucosa with and without intestinal metaplasia: effect of eradication of Helicobacter pylori

Hepatocyte nuclear factor 4α as a sensitive marker for uterine endocervical adenocarcinomas and their precursors

CONTEXT

Hepatocyte nuclear factor (HNF)-4α is a marker of gastrointestinal tumor differentiation; however, its expression in endocervical tumors remains unclear.

OBJECTIVE

We aimed to assess the utility of HNF4α expression as a marker for endocervical adenocarcinomas (ECAs) and adenocarcinoma in situs (AISs), and to establish a minimal panel for distinguishing them from nonneoplastic endocervical glandular lesions and metastases.

DESIGN

HNF4α expression was analyzed immunohistochemically (positive, H-score ≥10) in 323 tissue samples: 57 endocervical neoplasms including 35 glandular neoplasms and 22 squamous neoplasms, 144 nonneoplastic endocervical lesions, and 122 tumors from other organs. The panel for distinguishing endocervical glandular neoplasms from nonneoplastic glands and from metastases comprised HNF4α, p16, CDX2, and SATB2; staining was assessed.

RESULTS

HNF4α was expressed significantly in ECAs and AISs, both HPV-independent and -associated types, but not in nonneoplastic glandular and squamous lesions (p < 0.05). The immunohistochemical detection sensitivity and specificity for endocervical ECA and AIS were 77% and 95%, respectively. For AIS alone, these were 79% and 94%, and for ECA alone, 75% and 94%, respectively. Either HNF4α(+) or p16(+) or double positive identified endocervical gland and squamous neoplasms (sensitivity, 96%; specificity, 76%). HNF4α(+) and SATB2(-) and CDX2(-) profiles suggested ECAs (sensitivity, 69%; specificity, 88%). HNF4α(+) and SATB2(+) or CDX2(+) profiles suggested adenocarcinomas of the gastrointestinal or genital tract (sensitivity, 81%; specificity, 88%).

CONCLUSIONS

HNF4α is a promising marker for detecting both HPV-independent and -associated ECAs and AIS with high accuracy. Its combination with p16, CDX2, and SATB2 has potential use in diagnostic panels.

Gastric Intestinal Metaplasia: Real Culprit or Innocent Bystander as a Precancerous Condition for Gastric Cancer?

Gastric intestinal metaplasia (GIM), which denotes conversion of gastric mucosa into an intestinal phenotype, can occur in all regions of the stomach, including cardiac, fundic, and pyloric mucosa. Since the earliest description of GIM, its association with gastric cancer of the differentiated (intestinal) type has been a well-recognized concern. Many epidemiologic studies have confirmed GIM to be significantly associated with subsequent gastric cancer development. Helicobacter pylori, the principal etiologic factor for gastric cancer, plays the most important role in predisposing to GIM. Although the role of GIM in the stepwise progression model of gastric carcinogenesis (the so-called "Correa cascade") has come into question recently, we review the scientific evidence that strongly supports this long-standing model and propose a new progression model that builds on the Correa cascade. Eradication of H pylori is the most important method for preventing gastric cancer globally, but the effect of eradication on established GIM, is limited, if any. Endoscopic surveillance for GIM may, therefore, be necessary, especially when there is extensive corpus GIM. Recent advances in image-enhanced endoscopy with integrated artificial intelligence have facilitated the identification of GIM and neoplastic lesions, which will impact preventive strategies in the near future.

From microbiota toward gastro-enteropancreatic neuroendocrine neoplasms: Are we on the highway to hell?

Gut microbiota is represented by different microorganisms that colonize the intestinal tract, mostly the large intestine, such as bacteria, fungi, archaea and viruses. The gut microbial balance has a key role in several functions. It modulates the host's metabolism, maintains the gut barrier integrity, participates in the xenobiotics and drug metabolism, and acts as protection against gastro-intestinal pathogens through the host's immune system modulation. The impaired gut microbiota, called dysbiosis, may be the result of an imbalance in this equilibrium and is linked with different diseases, including cancer. While most of the studies have focused on the association between microbiota and gastrointestinal adenocarcinomas, very little is known about gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs). In this review, we provide an overview concerning the complex interplay between gut microbiota and GEP NENs, focusing on the potential role in tumorigenesis and progression in these tumors.

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.

Green epithelium revealed by narrow-band imaging (NBI): a feature for practical assessment of extent of gastric cancer after H. pylori eradication

Background and study aims Assessment of the extent of gastric cancer detected by endoscopy after successful eradication of H. pylori is often difficult even with narrow-band imaging (NBI)-magnifying endoscopy. Using the latter modality, it has often been noted that the cancerous area has a brownish color surrounded by green epithelium (GE). If the histological origin of this GE could be clarified, it could be of practical use for endoscopic assessment of the extent of cancer.

Materials and methods The endoscopic appearance of gastric cancer after eradication therapy was classified into four types: (A) cancer brownish, surrounding mucosa green; (B) cancer brownish, surrounding mucosa brownish; (C) cancer green, surrounding mucosa brownish; and (D) cancer green, surrounding mucosa green. A histological series of sections taken from tissues in each endoscopic view was stained with HE, and also for CDX2, MUC2, CD10 and MUC5AC. Staining intensity was evaluated by microscopy using a visual analog scale ranging from 0 to 3+: intensities of 0 and 1+ were rated as negative, and those of 2+ and 3+ as positive. Positive or negative immunostaining was examined for each type of endoscopic appearance A – D.

Results Among 42 lesions examined, 16 were type A, 18 type B, 6 type C and 2 type D. MUC2 was positive in the surrounding mucosa in 100 % of type A and D cases, but in only 28 % and 17 % of type B and C cases, respectively.

Conclusions GE observed by NBI-endoscopy corresponds to MUC2-positive mucosa and is thought to be a feature for practical assessment of the extent of cancer.

Endoscopic and Immunohistochemical Characteristics of Gastric Cancer with versus without Helicobacter Pylori Eradication

BACKGROUND/AIMS

The rate of gastric cancer (GC) after Helicobacter pylori eradication has gradually increased; therefore, we investigate the clinicopathological features of GC following eradication in comparison with those of GC with H. pylori infection.

METHODS

This study included 50 subjects with GC after eradication (GCE) and 151 patients with GC with H. pylori infection (GCI). Clinicopathological factors were assessed. The manifestation of GC was further evaluated using immunohistochemical analysis and in situ hybridization.

RESULTS

Macroscopic analysis revealed a significantly higher ratio of depressed type /elevated type in the GCE compared with the GCI (30/19 vs. 61/77, p = 0.041). The gastric phenotype was more common in the GCE compared with the GCI, and the proportion of CDX2-positive cases was lower in the GCE (8 out of 18; 44.4%) compared with the GCI (18 out of 19; 94.7%; p = 0.00082). Ki-67 labeling index was significantly lower in the GCE (32.03 ± 22.15) compared with the GCI (79.20 ± 14.87, p < 0.0001). No patient in the GCE showed evidence of Epstein-Barr virus infection.

CONCLUSION

The clinicopathological characteristics of GC following H. pylori eradication differ from those of GC in patients with H. pylori infection in terms of morphology, mucin phenotype, and proliferation rate.

CDX2 Expression in Gastric Carcinoma: A Clinicopathological Study

Background: Gastric cancer accounts for 7.8% of cancers worldwide and adenocarcinoma is the commonest histological type. Both gastric and intestinal phenotypic cell markers are expressed in gastric carcinomas. CDX2 is an intestinal transcription factor, which can be demonstrated in intestinal metaplasia and gastric carcinomas of the intestinal type. Unlike colorectal carcinomas, the role of CDX2 in gastric carcinomas as a prognostic variable is yet to be established. Ki-67 is a transcription factor expressed in the growth and synthetic phases of the cell cycle. Aims and Objectives: The aims of the study were to analyze CDX2 expression and Ki-67 labeling index in different histological types of gastric carcinomas and their relationship with the patients' clinicopathological parameters. Materials and Methods: A total of 50 gastric carcinoma cases were evaluated histologically and phenotypically, along with assessment of CDX2 expression and Ki-67 labeling index. Gastric carcinomas were grouped into intestinal and diffuse types, according to Lauren classification. A semiquantitative microscopic evaluation of CDX2 expression and Ki-67 labeling index was performed and correlated with the patients' clinicopathological parameters. Results: Increased CDX2 expression correlated with higher proportion of intestinal type gastric carcinomas and a lower proportion of lymph node metastasis, lymphovascular and perineural invasion. On the other hand, high Ki-67 labeling index was found in high grade tumors with lymphovascular invasion. Conclusions: The results of our study suggest that CDX2 might be a useful marker in predicting the prognosis of patients with gastric carcinoma. Accordingly, Ki-67 index seems to be useful in identifying a group of patients with aggressive tumors.

Expression of CDX2 in gastric cardia adenocarcinoma and its correlation with H. pylori and cell proliferation

BACKGROUND

Gastric cardia cancer (GCC) is located in the distal stomach, and strongly correlates with atrophic gastritis and Helicobacter pylori (H.pylori) infection. Caudal-related homeobox transcription factor 2 (CDX2) is homeobox gene encoding an intestine-specific transcription factor usually expressed in the intestinal epithelium cells. However, in several recent published papers, CDX2 was found to be aberrantly expressed in gastric, thyroid and ovarian cancer.

RESULTS

Higher expression of CDX2 was found in GCC tissues in comparison with non-malignant cardia mucosa (p<0.05). Moreover, immunohistochemical analysis demonstrated that CDX2 expression correlated with lymphatic metastasis. In addition, we found that CDX2 expression progressively increased with the level of H. pylori infection (p<0.05), and also correlated with cell proliferation, based on Ki67 staining.

METHODS

To investigate the relationship between CDX2, cell proliferation and H. pylori infection, we detected CDX2, Ki62 and H.pylori expression in 83 non-malignant gastric cardia mucosacases and 60 GCC specimens in the Chaoshan area, a high-risk region for esophageal and gastric cardia cancer.

CONCLUSION

These findings provide pathological evidence that H. pylori infectionis a driving force of gastric cardia carcinogenesis by upregulating CDX2 and inducing inflammation. These results provide new pathological evidence that H. pylori infection induces GCC tumorigenesis.

Follow-Up Study on CDX1 and CDX2 mRNA Expression in Noncancerous Gastric Mucosae After Helicobacter pylori Eradication

BACKGROUND

Changes in CDX1/CDX2 in gastric mucosae following Helicobacter pylori eradication have not been clarified yet.

AIMS

To evaluate the changes in CDX1/CDX2 expression after H. pylori eradication, in relation to the reversibility of intestinal metaplasia (IM).

METHODS

Time course of CDX1/CDX2 expressions was investigated in 176 subjects with various gastroduodenal disorders. Among them, 132 patients were H. pylori positives; H. pylori were eradicated in 107 of them; 13 failed to eradicate; and 12 did not receive H. pylori eradication therapy. Forty-four subjects were H. pylori negatives. Expression levels in CDX1 and CDX2 from noncancerous gastric mucosae of the corpus, as well as the histologic findings of gastric mucosae, were evaluated during the follow-up.

RESULTS

Average follow-up duration was 33.7 months (range 2-97 months). Expression levels in both CDX1 and CDX2 mRNAs were correlated with IM grade in the corpus (ρ = 0.633 and 0.554, respectively, all P < 0.001). Changes in CDX1/CDX2 mRNA expressions following H. pylori eradication showed only insignificant results; IM grade at the antrum and corpus showed a tendency to decrease after H. pylori eradication without statistical significance (P > 0.05). However, histologic improvement of IM at the corpus was associated with a decrease in CDX2 mRNA expression during the follow-up (linear mixed model, P for slope = 0.015).

CONCLUSIONS

In this study, eradication of H. pylori did not show any beneficial effects on aberrant CDX1/CDX2 expressions or IM. Reversibility of IM may be associated with a decrease in CDX2 mRNA expression.

Transcommitment: Paving the Way to Barrett's Metaplasia

Barrett's esophagus is the condition in which metaplastic columnar epithelium that predisposes to cancer development replaces stratified squamous epithelium in the distal esophagus. Potential sources for the cell or tissue of origin for metaplastic Barrett's epithelium are reviewed including native esophageal differentiated squamous cells, progenitor cells native to the esophagus located within the squamous epithelium or in the submucosal glands or ducts, circulating bone marrow-derived stem cells, and columnar progenitor cells from the squamocolumnar junction or the gastric cardia that proximally shift into the esophagus to fill voids left by damaged squamous epithelium. Wherever its source the original cell must undergo molecular reprogramming (i.e., either transdifferentiation or transcommitment) to give rise to specialized intestinal metaplasia. Transcription factors that specify squamous, columnar, intestinal, and mucus-secreting epithelial differentiation are discussed. An improved understanding of how esophageal columnar metaplasia forms could lead to development of effective treatment or prevention strategies for Barrett's esophagus. It could also more broadly inform upon normal tissue development and differentiation, wound healing, and stem cell biology.

Comparative analysis of gastrointestinal microbiota between normal and caudal-related homeobox 2 (cdx2) transgenic mice

Background/Aims

Caudal-related homeobox 2 (Cdx2) is expressed in the human intestinal metaplastic mucosa and induces intestinal metaplastic mucosa in the Cdx2 transgenic mouse stomach. Atrophic gastritis and intestinal metaplasia commonly lead to gastric achlorhydria, which predisposes the stomach to bacterial overgrowth. In the present study, we determined the differences in gut microbiota between normal and Cdx2 transgenic mice, using quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

Methods

Twelve normal (control) and 12 Cdx2 transgenic mice were sacrificed, and the gastric, jejunal, ileac, cecal and colonic mucosa, and feces were collected. To quantitate bacterial microbiota, we used real-time qRTPCR with 16S rRNA gene-targeted, species-specific primers.

Results

The total numbers of bacteria in the gastric, jejunal, ileac, cecal, and colonic mucosa of the Cdx2 transgenic mice were significantly higher than those of the normal mice. The Bacteroides fragilis group and also Prevotella were not detected in the stomach of the normal mice, although they were detected in the Cdx2 transgenic mice. Moreover, the Clostridium coccoides group, Clostridium leptum subgroup, Bacteroides fragilis group, and Prevotella were not detected in the jejunum or ileum of the normal mice, although they were detected in the Cdx2 transgenic mice. The fecal microbiota of the normal mice was similar to that of the Cdx2 transgenic mice.

Conclusions

Our results showed the differences in composition of gut microbiota between normal and Cdx2 transgenic mice, which may be caused by the development of gastric achlorhydria and intestinal metaplasia in Cdx2 transgenic mice.

Utilization of CDX2 expression in diagnosing pancreatic ductal adenocarcinoma and predicting prognosis

CDX2, a master transcriptional regulator of intestinal cell differentiation and survival, has been used as a marker to indicate colorectal lineage in adenocarcinomas of unknown origin. Pancreatic ductal adenocarcinoma (PDAC) is one of the most common causes for adenocarcinomas of unknown origin, but CDX2 expression in pancreatic disease remains unclear. In this study, we systemically and extensively investigated the expression and role of CDX2 in PDAC. We reported that CDX2 expression is weak and heterogeneous is all normal pancreas and chronic pancreatitis. It is largely expressed in epithelial-lining cells of pancreatic ducts including main ducts, inter-lobular ducts, intra-lobular ducts, intercalated ducts and centroacinar cells, but not in acinar cells or islet cells. CDX2 expression is down regulated during the transformation process from PanIN to PDAC. Only one third of PDACs retain some degree of CDX2 expression, and this group of PDACs have reduced median survival time compared to that of CDX2 negative group (308 days vs. 586 days, p = 0.0065). Metastatic PDACs remain similar expression pattern to that of the primary sites. Our study clearly demonstrates CDX2 expression in pancreatic diseases including PDAC, which is practically important when CDX2 is used to establish the primary sites of adenocarcinomas of unknown origin. In addition, our study also provides CDX2 as a prognostic marker for PDAC and implicates an important role of CDX2 in the development of normal pancreas and PDAC.

Transgenic overexpression of cdx1b induces metaplastic changes of gene expression in zebrafish esophageal squamous epithelium

Cdx2 has been suggested to play an important role in Barrett's esophagus or intestinal metaplasia (IM) in the esophagus. To investigate whether transgenic overexpression of cdx1b, the functional equivalent of mammalian Cdx2 in zebrafish, may lead to IM of zebrafish esophageal squamous epithelium, a transgenic zebrafish system was developed by expressing cdx1b gene under the control of zebrafish keratin 5 promoter (krt5p). Gene expression in the esophageal squamous epithelium of wild-type and transgenic zebrafish was analyzed by Affymetrix microarray and confirmed by in situ hybridization. Morphology, mucin expression, cell proliferation, and apoptosis were analyzed by hematoxylin & eosin (HE) staining, Periodic acid Schiff (PAS) Alcian blue staining, proliferating cell nuclear antigen (PCNA) immunohistochemical staining, and TUNEL assay as well. cdx1b was found to be overexpressed in the nuclei of esophageal squamous epithelial cells of the transgenic zebrafish. Ectopic expression of cdx1b disturbed the development of this epithelium in larval zebrafish and induced metaplastic changes in gene expression in the esophageal squamous epithelial cells of adult zebrafish, that is, up-regulation of intestinal differentiation markers and down-regulation of squamous differentiation markers. However, cdx1b failed to induce histological IM, or to modulate cell proliferation and apoptosis in the squamous epithelium of adult transgenic zebrafish.

No association between the CDX2 G543C polymorphism and risk of gastric atrophy and cancer

Ectopic expression of CDX2 in the stomach is closely associated with chronic Helicobacter pylori (H. pylori) infection and intestinal metaplasia. Whether CDX2 has tumor suppression or tumorigenesis potential remains to be elucidated. In this study, we investigated the association between the CDX2 G543C polymorphism (silent mutation) and the risk for H. pylori-induced gastric atrophy and cancer as well as H. pylori infection, using 454 Japanese subjects undergoing a health checkup and 202 gastric cancer patients. The frequency of the minor allele was the same as previously reported in China, but different from that reported in England. CDX2 G543C was not associated with risk of H. pylori infection, gastric atrophy, or gastric cancer, although the point estimate for non-cardiac differentiated gastric cancer as compared to controls with gastric atrophy was 2.22 (95%CI=0.17-29.4). In conclusion, our results indicate that the CDX2 G543C polymorphism is unlikely to affect the H. pylori infection-gastric atrophy-gastric cancer sequence.

Expression and significance of homeodomain protein Cdx2 in gastric carcinoma and precancerous lesions

AIM: To investigate the expression and significance of caudal-related homeobox transcription factor (Cdx2) in gastric carcinoma (GC) and precancerous lesions.

METHODS: The expression of Cdx2 in GC, precancerous lesions and normal gastric mucosa were detected using immunohistochemical method. Hematoxylin and eosin staining, alcian blue/periodic acid-schiff and high iron diamine/alcian blue staining were used to classify intestinal metaplasia (IM) and GC.

RESULTS: Cdx2 was not detected in normal gastric mucosa. Cdx2 expression was detected in 87.1% (101/116) of IM, 50% (36/72) of dysplasia and 48.2% (41/85) of GC. The Cdx2-expressing cells in IM were more prevalent than in dysplasia and carcinoma (P < 0.05). There was no relationship between Cdx2 expression and the classification of IM or the degree of dysplasia. Expression of Cdx2 was significantly higher in intestinal-type carcinoma than in diffuse and mixed-type carcinoma (P < 0.05). Positive expression of Cdx2 was mainly found in moderately to well differentiated GC. There was a negative association between nuclear Cdx2 expression and lymph node metastasis and tumor, nodes, metastasis stage of GC (P < 0.05). The patients with Cdx2-positive expression showed a higher survival rate than those with Cdx2-negative expression (P = 0.038). Multivariate analysis revealed that the expression of Cdx2 and lymph node metastasis were independent prognostic indicators of GC (P < 0.05).

CONCLUSION: Cdx2 may be closely related to IM and the intestinal-type GC and implicate better biological behavior and outcome. Cdx2 is useful for predicting the prognosis of GC.

The Role of CDX2 in Intestinal Metaplasia Evaluated Using Immunohistochemistry

Background/Aims

Intestinal metaplasia (IM) has been regarded as a premalignant condition. This study evaluated the role of the transforming factor CDX2 according to the severity and type of IM.

Methods

This analysis was performed on 383 subjects with IM in the antrum and/or body, with diagnoses that were categorized as controls, dysplasias, and gastric cancers. The IM grades were classified into four groups as negative, mild, moderate or severe using the updated Sydney scoring system. The IM subtypes were categorized as type I, type II, and type III using high iron diamine and alcian blue (pH 2.5) staining. The CDX2 expression in the IM foci was evaluated using immunohistochemistry in specimens from the antrum and/or body.

Results

CDX2 expression increased according to IM severity (p=0.001) but was not associated with the IM subtype (p=0.881) in the antrum specimens. Similarly, CDX2 expression increased according to the IM grade (p=0.001) but was not associated with the IM subtype (p=0.755) in the body specimens. CDX2 expression was also increased according to baseline disease in the antrum, especially dysplastic and GC group (p=0.003), but not in the body (p=0.582). However, status of Helicobacter pylori infection was not associated with CDX2 expression in the antrum (p=0.692) and body (p=0.271).

Conclusions

These results show that CDX2 expression is associated with the IM grade regardless of the IM subtype and that it was more frequent in the dysplasia group. These results suggest that CDX2 expression might play an important role in the progression of IM in various environments that can affect neoplastic change.

Predictability of Gastric Intestinal Metaplasia by Mottled Patchy Erythema Seen on Endoscopy

BACKGROUND

Intestinal metaplasia (IM) is regarded as a premalignant lesion. However, endoscopic diagnosis of IM has been considered difficult. Using endoscopy, we found a unique pattern of erythema, "Mottled Patchy Erythema (MPE)," which includes severe IM. Helicobacter pylori (Hp) infection itself can cause erythema, which reflects histologic changes in the gastric mucosa. Therefore we enrolled Hp eradication patients to validate the relation between MPE and pathologic findings.

METHODS

We enrolled patients with chronic gastritis who underwent successful Hp eradication at least 6 months before the study. We defined MPE as multiple flat or depressed erythematous lesions. When encountering MPE on endoscopy, we performed biopsy on both the MPE site and non-MPE site. The non-MPE site was defined as an adjacent mucosa located within 3 cm of the MPE site. All biopsy specimens were evaluated immunohistochemically for IM subtype using MUC2, MUC5AC, MUC6, CD10, and CDX2 stains. The degree of IM was defined according to the Updated Sydney System. The diagnostic accuracy of the MPE findings for pathologic IM was calculated. The relation between MPE and IM subtype was also assessed.

RESULTS

A total of 102 patients were selected for the study. Of these, 55 (54%) patients had MPE. Biopsy specimens were taken from the MPE sites and non-MPE sites from these 55 patients. The IM percentages and median scores of IM were both significantly higher at the MPE sites (P < 0.001) than at the non-MPE sites. The sensitivity and specificity for MPE in the detection of histologic IM were 72.7% and 84.1%, respectively. No significant associations were observed in the expression of MUC2, MUC5AC, MUC6, CD10, and CDX2 between the MPE sites and non-MPE sites. There were no significant differences in the ratios (complete/incomplete) of IM subtypes between the two groups.

CONCLUSIONS

MPE is a useful endoscopic finding to detect histologic IM without the use of chromoendoscopy and magnifying endoscopy. However, the IM subtype is difficult to identify. In the era of Hp eradication, MPE has the potential to become a predictive finding for the risk of gastric cancer.

Genetic Mechanisms and Aberrant Gene Expression during the Development of Gastric Intestinal Metaplasia and Adenocarcinoma

Gastric adenocarcinoma occurs via a sequence of molecular events known as the Correa’s Cascade which often progresses over many years. Gastritis, typically caused by infection with the bacterium H. pylori, is the first step of the cascade that results in gastric cancer; however, not all cases of gastritis progress along this carcinogenic route. Despite recent antibiotic intervention of H. pylori infections, gastric adenocarcinoma remains the second most common cause of cancer deaths worldwide. Intestinal metaplasia is the next step along the carcinogenic sequence after gastritis and is considered to be a precursor lesion for gastric cancer; however, not all patients with intestinal metaplasia develop adenocarcinoma and little is known about the molecular and genetic events that trigger the progression of intestinal metaplasia into adenocarcinoma. This review aims to highlight the progress to date in the genetic events involved in intestinal-type gastric adenocarcinoma and its precursor lesion, intestinal metaplasia. The use of technologies such as whole genome microarray analysis, immunohistochemical analysis and DNA methylation analysis has allowed an insight into some of the events which occur in intestinal metaplasia and may be involved in carcinogenesis. There is still much that is yet to be discovered surrounding the development of this lesion and how, in many cases, it develops into a state of malignancy.

Cell lineage dynamics in the process leading to intestinal metaplasia

BACKGROUND

Gene expression in the early stage of the transition to intestinal metaplasia in human gastric mucosa has not been determined. In this study, we investigated the temporal relationship between cell lineage changes and intestine-specific gene expression in the process leading to intestinal metaplasia, using Cdx2-transgenic mice.

METHODS

Cellular phenotypes were analyzed by immunohistochemistry and were compared with the gene expression profiles of cell lineage markers by real-time polymerase chain reaction.

RESULTS

Up to postnatal day (PD) 20, the gastric mucosae of Cdx2-transgenic mice were histologically similar to those of their normal littermates. However, at approximately PD 20, we observed the sporadic appearance of glands in which all the epithelial cells expressed Cdx2 (Cdx2-diffuse positive glands). In the Cdx2-diffuse positive glands, parietal cells had disappeared, the proliferating zone had moved from the isthmus to the base, and absorptive cells and goblet cells were recognized. In contrast, the surrounding mucosa retained the phenotype of the gastric gland in which only some of the epithelial cells expressed Cdx2. During PDs 30 and 40, the entire fundic mucosa changed to transdifferentiated mucosa that was a composite of intestinal metaplasia and spasmolytic polypeptide-expressing metaplasia. An increase in the expression of intestine-specific genes, with a reciprocal decrease in gastric-specific gene expression, began much earlier than the emergence of Cdx2-diffuse positive glands.

CONCLUSIONS

A dramatic increase in intestine-specific gene expression precedes the morphological appearance of intestinal metaplasia and spasmolytic polypeptide-expressing metaplasia.

CDX1 and CDX2 expression in intestinal metaplasia, dysplasia and gastric cancer

Intestinal metaplasia (IM) has been regarded as a premalignant condition. However, the pathogenesis of IM is not fully understood. The aim of this study was to evaluate the role of CDX1 and CDX2 in the formation of IM and the progression to dysplasia and gastric cancer (GC). A total of 270 subjects included 90 with GC, dysplasia and age- and sex-matched controls. Real-time PCR (RT-PCR) was performed with body specimens for CDX1 and CDX2. The expression of CDX2 was significantly higher in H. pylori positive group than H. pylori negative group (P = 0.045). CDX1 and CDX2 expression increased proportional to the IM grade of the body (P < 0.001). CDX2 expression was significantly higher in incomplete type of IM than in complete type (P = 0.045). The expression of CDX1 in dysplasia group was significantly higher than in the control group (P = 0.001); in addition, CDX1 and CDX2 in cancer group was significantly higher than control group (P < 0.001, and P < 0.001, respectively). Aberrant expression of CDX1 and CDX2 correlated with H. pylori infection and grade of IM in the body. Furthermore, the results suggest that CDX1 and CDX2 play a role in the progression to GC and dysplasia.

Expression of Claudin-2 in intestinal metaplastic mucosa of Cdx2-transgenic mouse stomach

OBJECTIVE

Cdx2 is expressed in human intestinal metaplastic mucosa and induces intestinal metaplastic mucosa in Cdx2-transgenic mouse stomach. Claudin-2 is a structural component of tight junctions in the intestine and Cdx2 activates the Claudin-2 promoter in the human intestinal epithelial cell line Caco-2. Our aim is to evaluate the expression of Claudin-2 in intestinal metaplastic mucosa of Cdx2-transgenic mouse stomach.

MATERIAL AND METHODS

The Claudin-2 expression in the normal gastric mucosa and normal intestinal mucosa of wild type mice and the intestinal metaplastic mucosa of Cdx2-transgenic mice was analyzed by immunohistochemistry, Western blotting and quantitative real-time PCR (qRT-PCR).

RESULTS

Claudin-2 was expressed in the base of the glands in intestine and intestinal metaplasia while it was not expressed in the body of stomach. Claudin-2 expression was found in the antrum of stomach, while it was weaker than that in the intestine and the intestinal metaplasia. Claudin-2 was also detected in intestinal metaplasia, colon and ileum by both Western blotting and qRT-PCR while it was not detected in gastric body.

CONCLUSION

These results suggest that Cdx2 plays an important role in the expression of Claudin-2 in vivo.

Relevance of high virulence Helicobacter pylori strains and futility of CDX2 expression for predicting intestinal metaplasia after eradication of infection

OBJECTIVE

Different Helicobacter pylori genotypes are associated with distinct inflammatory responses and consequent development of pre-neoplastic lesions, namely intestinal metaplasia (IM), which is dependent on the expression of CDX2. We aimed to evaluate IM progression/regression in the context of H. pylori eradication, bringing into play the effect of the virulence of infecting H. pylori strains and the hypothesis that CDX2 expression might be a marker for later development of IM.

MATERIAL AND METHODS

Sixty-five male volunteers were evaluated by endoscopy before H. pylori eradication and after a median six-year follow-up. Histological diagnosis was performed at baseline and follow-up, and baseline H. pylori genotypes and CDX2 expression in non-metaplastic foci were also assessed.

RESULTS

Fifty-one individuals remained free from infection at follow-up. Six out of 27 who had no metaplastic lesions at baseline developed IM. CDX2 nuclear expression was observed in 15 of the 21 cases (71.4%) showing no progression to IM, and in three out of six cases (50%) with progression to IM (p = 0.367). Six of the 24 cases with IM at baseline showed regression to less severe outcomes, which was less frequent in those infected with high-virulence strains (7.7% vs. 50%, p = 0.047). In the latter there is a significant persistence of lymphoid follicles.

CONCLUSIONS

Our results support that under infection with high virulence H. pylori strains, IM is a point of difficult return in the gastric carcinogenic pathway. The appearance of CDX-expressing cells in non-metaplastic foci was not associated with the development of IM during the six-year follow-up.

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.

Direct repression of Sonic Hedgehog expression in the stomach by Cdx2 leads to intestinal transformation

Shh (Sonic Hedgehog) is a morphogen involved in gastric fundic gland differentiation in the adult. Shh expression is reduced in Helicobacter pylori-associated intestinal metaplastic change of the gastric epithelium and mice that lack Shh show intestinal transformation of the gastric mucosa. Similarly, in the stomach of Cdx2 (caudal-type homeobox 2)-transgenic mice, the gastric mucosa is replaced by intestinal metaplastic mucosa. The aim of the present study was to use Cdx2-transgenic mice to investigate: (i) Shh expression in the intestinal metaplastic mucosa of the Cdx2-transgenic mouse stomach; and (ii) the relationship between Shh and Cdx2. We determined that Shh mRNA levels were dramatically reduced in the intestinal metaplastic mucosa of the Cdx2-transgenic mouse stomach compared with the normal (wild-type) mouse stomach. This was not due to hypermethylation of the Shh promoter, but instead we showed that Cdx2 directly bound to the TATA box region of the Shh promoter. Cdx2 also down-regulated transcription of the Shh gene in the human gastric carcinoma cell lines AGS, MKN45 and MKN74. In conclusion, Cdx2 reduced Shh expression by binding to the unmethylated Shh promoter in the intestinal metaplastic mucosa of Cdx2-transgenic mouse stomach.

Modelling Barrett's oesophagus

Barrett's oesophagus is the replacement of normal squamous oesophageal epithelium with an intestinalized columnar epithelium. Although some insight has been gained as to what Barrett's oesophagus is, how this columnar epithelium emerges from within a stratified squamous epithelium remains an unanswered question. We have sought to determine whether oesophageal keratinocytes can be trans-differentiated into Barrett's oesophagus cells. Using an Affymetrix microarray, we found unexpectedly that gene-expression patterns in the Barrett's oesophagus were only slightly more similar to the normal small intestine than they were to the normal oesophagus. Thus gene-expression patterns suggest significant molecular similarities remain between Barrett's oesophagus cells and normal squamous oesophageal epithelium, despite their histological resemblance with intestine. We next determined whether directed expression of intestine-specific transcription factors could induce intestinalization of keratinocytes. Retroviral-mediated Cdx2 (Caudal-type homeobox 2) expression in immortalized human oesophageal keratinocytes engineered with human telomerase reverse transcriptase (EPC2-hTERT cells) could be established transiently, but not maintained, and was associated with a reduction in cell proliferation. Co-expression of cyclin D1 rescued proliferation in the Cdx2-expressing cells, but co-expression of dominant-negative p53 did not. Cdx2 expression in the EPC2-hTERT.D1 cells did not induce intestinalization. However, when combined with treatments that induce chromatin remodelling, there was a significant induction of Barrett's oesophagus-associated genes. Studies are ongoing to determine whether other intestinal transcription factors, either alone or in combination, can provoke greater intestinalization of oesophageal keratinocytes. We conclude that, on the basis of gene-expression patterns, Barrett's oesophagus epithelial cells may represent an intermediate between oesophageal keratinocytes and intestinal epithelial cells. Moreover, our findings suggest that it may be possible to induce Barrett's oesophagus epithelial cells from oesophageal keratinocytes by altering the expression of certain critical genes.

Bile acids induce cdx2 expression through the farnesoid x receptor in gastric epithelial cells

Clinical and experimental studies showed that the reflux of bile into the stomach contributes to the induction of intestinal metaplasia of the stomach and gastric carcinogenesis. Caudal-type homeobox 2 (Cdx2) plays a key role in the exhibition of intestinal phenotypes by regulating the expression of intestine-specific genes such as goblet-specific gene mucin 2 (MUC2). We investigated the involvement of the farnesoid X receptor (FXR), a nuclear receptor for bile acids, in the chenodeoxycholic acid (CDCA)-induced expression of Cdx2 and MUC2 in normal rat gastric epithelial cells (RGM-1 cells). RGM-1 cells were treated with CDCA or GW4064, an FXR agonist, in the presence or absence of guggulsterone, an FXR antagonist. CDCA induced dose-dependent expression of Cdx2 and MUC2 at both the mRNA and protein levels. The maximum stimulation of Cdx2 and MUC2 mRNA induced by CDCA was observed at 3 h and by 6 h, respectively. GW4064 also induced expression of these molecules. The effects of CDCA and GW4064 on expression of Cdx2 and MUC2 were abolished by guggulsterone. These findings suggest that bile acids may induce gastric intestinal metaplasia and carcinogenesis through the FXR.

Pathogenic bacteria induce colonic PepT1 expression: an implication in host defense response

BACKGROUND & AIMS

Expression of the di/tripeptide transporter PepT1 has been observed in the colon under inflammatory conditions; however, the inducing factors and underlying mechanisms remain unknown. Here, we address the effects of pathogenic bacteria on colonic PepT1 expression together with its functional consequences.

METHODS

Human colonic HT29-Cl.19A cells were infected with the attaching and effacing enteropathogenic Escherichia coli (EPEC). Wild-type and PepT1 transgenic mice or cultured colonic tissues derived from these mice were infected with Citrobacter rodentium, a murine attaching and effacing pathogen related to EPEC.

RESULTS

EPEC induced PepT1 expression and activity in HT29-Cl.19A cells by intimately attaching to host cells through lipid rafts. Induction of PepT1 expression by EPEC required the transcription factor Cdx2. PepT1 expression reduced binding of EPEC to lipid rafts, as well as activation of nuclear factor-kappaB and mitogen-activated protein kinase and production of interleukin-8. Accordingly, ex vivo and in vivo experiments revealed that C rodentium induced colonic PepT1 expression and that, compared with their wild-type counterparts, PepT1 transgenic mice infected with C rodentium exhibited decreased bacterial colonization, production of proinflammatory cytokines, and neutrophil infiltration into the colon.

CONCLUSIONS

Our findings demonstrate a molecular mechanism underlying the regulation of colonic PepT1 expression under pathologic conditions and reveal a novel role for PepT1 in host defense via its capacity to modulate bacterial-epithelial interactions and intestinal inflammation.

Transgenic Cdx2 induces endogenous Cdx1 in intestinal metaplasia of Cdx2-transgenic mouse stomach

Cdx1 and Cdx2, which are transcription factors regulating normal intestinal development, have been studied as potential key molecules in the pathogenesis of the precancerous intestinal metaplasia of the human stomach. However, the regulation of Cdx1 expression in the intestinal metaplasia is poorly understood. Cdx2-expressing gastric mucosa of Cdx2-transgenic mouse stomach was replaced by intestinal metaplastic mucosa. The aim of this study was to investigate the following: (a) Cdx1 expression in the intestinal metaplastic mucosa of the Cdx2-transgenic mouse stomach; and (b) the relationship between Cdx1 and Cdx2. A mouse model of intestinal metaplasia, the Cdx2-transgenic mouse, was used to investigate Cdx1 gene expression by RT-PCR. DNA methylation profile analysis was performed by bisulfite sequencing, and the interaction of Cdx2 with the Cdx1 promoter was examined by chromatin immunoprecipitation assay, electrophoretic mobility shift assay, and luciferase reporter assays. Cdx2 mRNA was expressed in the Cdx2-transgenic mouse stomach. However, endogenous Cdx2 mRNA was not expressed in the intestinal metaplasia of the Cdx2-transgenic mouse stomach. On the other hand, endogenous Cdx1 mRNA and protein were expressed in the intestinal metaplasia of the Cdx2-transgenic mouse stomach. The Cdx1 promoter was unmethylated in the intestinal metaplasia of the Cdx2-transgenic mouse stomach. Chromatin immunoprecipitation assay and electrophoretic mobility shift assay showed that Cdx2 was bound to the Cdx1 promoter region in the intestinal metaplasia and the normal intestine. Cdx2 upregulated and siRNA-Cdx2 downregulated the transcriptional activity of the Cdx1 gene in the human gastric carcinoma cell lines AGS, MKN45, and MKN74. In conclusion, transgenic Cdx2 induced endogenous Cdx1 through the binding of Cdx2 to the unmethylated Cdx1 promoter region in the intestinal metaplasia of the Cdx2-transgenic mouse stomach.

Intestinal metaplasia in gallbladder correlates with high amylase levels in bile in patients with a morphologically normal pancreaticobiliary duct

We reported previously that intestinal metaplasia in the gallbladder is strongly associated with expression of caudal-related homeobox transcription factor Cdx2. It has been documented that occult pancreatobiliary reflux, even in the absence of pancreaticobiliary maljunction, is associated with elevated risk of biliary malignancy. We ascertained the correlation between intestinal metaplasia in the gallbladder and occult pancreatobiliary reflux. In 196 patients with a normal pancreaticobiliary ductal arrangement who had undergone laparoscopic cholecystectomy, we performed intraoperative cholangiography and measured amylase levels in bile sampled from the gallbladder. The cutoff value for high cystic amylase was defined as a biliary amylase level higher than the normal upper limit of serum amylase (215 IU/L). We also retrospectively reviewed the cholecystectomized tissue specimens to investigate the presence of intestinal metaplasia and expression of Cdx2. Then, we explored the relationship between intestinal metaplasia in the gallbladder and occult choledocho-pancreatic reflux. Intestinal metaplasia was found in 16.8% (33/196) of the gallbladders. The prevalence of choledocho-pancreatic reflux revealed by intraoperative cholangiography was not significantly different between cases with intestinal metaplasia (5/33, 15.2%) and those without (25/163, 15.3%; P = .81). However, in cases with intestinal metaplasia, the rate of high cystic amylase (13/33, 39.4%) was significantly higher compared with cases without intestinal metaplasia (26/163, 16.0%, P = .005). In conclusion, intestinal metaplasia in the gallbladder is significantly correlated with high amylase levels in bile in patients with a morphologically normal pancreaticobiliary ductal arrangement.

Alterations of gastric homeoprotein expression in Helicobacter pylori infection, incisural antralisation, and intestinal metaplasia

PURPOSE

This study was to determine whether gastric expression of homeoproteins is altered in Helicobacter pylori infection, incisural antralisation, and intestinal metaplasia (IM).

METHODS

Gastric biopsy specimens were taken from 98 patients with non-ulcer dyspepsia for the detection of H. pylori infection; histological examinations; immunohistochemical staining of CDX2, PDX1, PAX6, and NKX6.1.

RESULTS

Of the patients, 38 were positive for H. pylori infection, 44 had antral-type mucosa at the incisura, and 22 had IM in the stomach. At the incisura, the expression of PDX1, NKX6.1, and PAX6 in cytoplasm compartment was down-regulated in antral-type mucosa compared with that in the transitional- or body-type mucosa (all P<0.01). The expression of PDX1, PAX6, and NKX6.1 in cytoplasm at the incisura was down-regulated in H. pylori-infected patients compared with that in those without H. pylori infection (all P<0.01). CDX2 expression in whole stomach was up-regulated, but PDX1 expression at the incisura was down-regulated in patients with IM compared with that in those without IM (all P<0.01).

CONCLUSIONS

Gastric expression of PDX1, PAX 6, and NKX6.1 is down-regulated in H. pylori infection and incisural antralisation. CDX2 is up-regulated but PDX1 is down-regulated in the presence of IM.

Induction of intestinalization in human esophageal keratinocytes is a multistep process

Barrett's esophagus (BE) is the replacement of normal squamous esophageal mucosa with an intestinalized columnar epithelium. The molecular mechanisms underlying its development are not understood. Cdx2 is an intestine-specific transcription factor that is ectopically expressed in BE, but its role in this process is unclear. Herein, we describe a novel cell culture model for BE. Retroviral-mediated Cdx2 expression in immortalized human esophageal keratinocytes [EPC-human telomerase reverse transcriptase (hTERT)] could transiently be established but not maintained and was associated with a reduction in cell proliferation. Coexpression of cyclin D1, but not a dominant-negative p53, rescued proliferation in the Cdx2-expressing cells. Cdx2 expression in the EPC-hTERT.D1 cells decreased cell proliferation but did not induce intestinalization. We investigated for other treatments to enhance intestinalization and found that acidic culture conditions uniformly killed EPC-hTERT.D1.Cdx2 cells. However, treatment with 5-aza-2-deoxycytidine (5-AzaC) to demethylate epigenetically silenced genes did appear to be tolerated. Multiple Cdx2 target genes, markers of intestinal differentiation and markers of BE, were induced by this 5-AzaC treatment. More interestingly, the expression level of several of these genes was enhanced only in the EPC-hTERT.D1-Cdx2 cells treated with 5-AzaC. Two of these, SLC26a3/DRA (downregulated in adenoma) and Na+/H+ exchanger 2 (NHE2), were not previously known to be elevated in BE; however, we confirmed their elevation in BE tissue samples. 5-AzaC treatment also induced cell senescence, even at low doses. We conclude that ectopic proliferation signals, alterations in epigenetic gene regulation and the inhibition of tumor suppressor mechanisms are required for Cdx2-mediated intestinalization of human esophageal keratinocytes in BE.

Comprehensive evaluation of CDX2 in invasive cervical adenocarcinomas: immunopositivity in the absence of overt colorectal morphology

CDX2 is a member of the caudal-related homeobox gene family that is expressed during the normal development of the intestinal tract. In addition to staining adenocarcinomas of the alimentary system, studies have demonstrated CDX2 positivity in a percentage of ovarian mucinous and endometrioid tumors, carcinoids, and some adenocarcinomas of other sites such as the urinary bladder, prostate, lung, and pancreas. However, CDX2 immunostaining in cervical adenocarcinomas has not been examined in detail with comparison to important clinicopathologic characteristics including histopathologic subtype, tumor stage, and patient follow-up. In this study of 81 invasive cervical adenocarcinomas, 24 of the cases (30%) demonstrated nuclear positivity. Ten of the 15 (67%) endometrioid tumors had positive nuclear staining, compared with 7 of the 33 (21%) endocervical "usual-type" carcinomas, and 7 of the 33 (21%) remaining subtypes (adenosquamous, glassy cell, clear cell, serous, villoglandular, enteric). The frequency of nuclear staining for the endometrioid subtype was significantly different compared with that for the endocervical and other subtypes (P=0.003). Some cases showed granular cytoplasmic staining with or without corresponding nuclear positivity. Positive nuclear or cytoplasmic staining for CDX2 did not correlate with disease stage or patient outcome. Our results indicate that cervical adenocarcinomas can show nuclear immunopositivity for CDX2 even in the absence of overt morphologic features of colorectal differentiation. The frequency and pattern of CDX2 staining in the more common histologic subtypes of cervical adenocarcinoma (endocervical usual-type and endometrioid) is parallel to that which is seen for adenocarcinomas of the upper gastrointestinal tract and pancreaticobiliary system.

Helicobacter pylori infection induces a reversible expression of the CDX2 transcription factor protein in human gastric epithelium

OBJECTIVE

The homeobox gene CDX2 is implicated in the appearance of intestinal metaplasia in Helicobacter pylori gastritis. The aim of this study was to investigate whether CDX2 expression in gastric mucosa occurs before the appearance of overt intestinal metaplasia in H. pylori gastritis, and whether or not this expression is reversible.

MATERIAL AND METHODS

CDX2 was studied by immunohistochemistry in a cohort of 38 patients with H. pylori gastritis before and after eradication (mean follow-up 6.3 years) of H. pylori. A cohort of 49 individuals with healthy stomachs was analysed as a control.

RESULTS

In the control group no immunostaining of CDX2 in the epithelial cells of the gastric body was found, while in 57% of the cases a mild, aberrant nuclear immunostaining of CDX2 in the non-metaplastic epithelial cells in antrum, designated as "positive staining of single cells" (PSSC), was found. In H. pylori gastritis, the PSSC was seen in antrum and corpus in 100% and 26% of the cases, respectively. The prevalence of antral PSSC was significantly increased (on average by 4-fold) in H. pylori gastritis as compared with controls. After eradication of H. pylori, the prevalence of PSSC decreased significantly in antrum but not in corpus.

CONCLUSIONS

Expression of CDX2 at low intensity is common in the epithelium of normal antrum, and this expression is enhanced in H. pylori gastritis. Expression of CDX2 is reversible at least in antrum after eradication of H. pylori infection.

Biology of intestinal metaplasia in 2008: more than a simple phenotypic alteration

This review concentrates on one main aspect of cancerization in the oesophagus and stomach: principally, intestinal metaplasia. There are at least two other important pathways that lead to cancer and do not need such a morphological transformation. One is the gastric type of carcinoma on the Lauren classification, which arises directly from the stem cell zone and is the signet ring form of cancer, while the other is spasmolytic polypeptide-expressing metaplasia (SPEM)--spasmolytic polypeptide (TFF2) expressing metaplasia, where the gastric glands become filled with TFF2-expressing cells and may also lead to gastric dysplasia and cancer. The development of intestinal metaplasia is complex. Here, we examine intestinal metaplasia in molecular terms, noting the over-expression of Cdx1, Cdx2, Pdx1, Oct1, TFF3 and the downregulation of Hedgehog signalling; Runx3 is deactivated by epigenetic silencing, and pathways such as Wnt and MARK/ERK are involved. These changes start to explain the principles of the development of intestinal metaplasia and suggest that the regulation of these genes is of importance in the development of gastric cancer.

Multilayered epithelium in a rat model and human Barrett's esophagus: similar expression patterns of transcription factors and differentiation markers

Background

In rats, esophagogastroduodenal anastomosis (EGDA) without concomitant chemical carcinogen treatment leads to gastroesophageal reflux disease, multilayered epithelium (MLE, a presumed precursor in intestinal metaplasia), columnar-lined esophagus, dysplasia, and esophageal adenocarcinoma. Previously we have shown that columnar-lined esophagus in EGDA rats resembled human Barrett's esophagus (BE) in its morphology, mucin features and expression of differentiation markers (Lab. Invest. 2004;84:753–765). The purpose of this study was to compare the phenotype of rat MLE with human MLE, in order to gain insight into the nature of MLE and its potential role in the development of BE.

Methods

Serial sectioning was performed on tissue samples from 32 EGDA rats and 13 patients with established BE. Tissue sections were immunohistochemically stained for a variety of transcription factors and differentiation markers of esophageal squamous epithelium and intestinal columnar epithelium.

Results

We detected MLE in 56.3% (18/32) of EGDA rats, and in all human samples. As expected, both rat and human squamous epithelium, but not intestinal metaplasia, expressed squamous transcription factors and differentiation markers (p63, Sox2, CK14 and CK4) in all cases. Both rat and human intestinal metaplasia, but not squamous epithelium, expressed intestinal transcription factors and differentiation markers (Cdx2, GATA4, HNF1α, villin and Muc2) in all cases. Rat MLE shared expression patterns of Sox2, CK4, Cdx2, GATA4, villin and Muc2 with human MLE. However, p63 and CK14 were expressed in a higher proportion of rat MLE compared to humans.

Conclusion

These data indicate that rat MLE shares similar properties to human MLE in its expression pattern of these markers, not withstanding small differences, and support the concept that MLE may be a transitional stage in the metaplastic conversion of squamous to columnar epithelium in BE.

Quantitative analysis of the effect of Helicobacter pylori on the expressions of SOX2, CDX2, MUC2, MUC5AC, MUC6, TFF1, TFF2, and TFF3 mRNAs in human gastric carcinoma cells

OBJECTIVE

To investigate the phenotypic characters of carcinoma cells and the response of gastric epithelial cells to Helicobacter pylori (H. pylori) infection using the gastric carcinoma cell lines.

MATERIAL AND METHODS

Real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to assess the effect of H. pylori infection on mRNA levels of transcription factors (SOX2 and CDX2), mucin core proteins (MUC2, MUC5AC, and MUC6), and trefoil factor family peptides (TFF) (TFF1, TFF2, and TFF3) in gastric carcinoma cells (AGS, MKN45, and KATO III cells). H. pylori ATCC 43504 and its isogenic cag pathogenicity island (PAI) deleted mutant were used.

RESULTS

These cell lines expressed mixed gastric and intestinal phenotypes. The intestinal phenotype predominated in AGS cells and gastric phenotypes in MKN45 and KATO III cells. In all three cell lines, H. pylori infection inhibited SOX2 mRNA expression, but induced the three TFFs mRNAs. In AGS cells, H. pylori induced cag PAI-dependent mRNA expression of CDX2, MUC2, MUC5AC, and MUC6. mRNA expressions of CDX2, MUC5AC, and MUC6 were inhibited in KATO III cells, whereas MUC2 mRNA expression was unchanged. In MKN45 cells, H. pylori induced the three MUCs mRNAs but inhibited CDX2 mRNA expression.

CONCLUSIONS

This study provides a useful platform for selecting appropriate cell lines to model H. pylori-related changes in the gastric epithelium that mirror the changes seen in vivo. The outcome of H. pylori infection may reflect changes in the mucus gel layer caused by altered expression of mucins and TFF peptides.

Re-expression of sonic hedgehog and reduction of CDX2 after Helicobacter pylori eradication prior to incomplete intestinal metaplasia

Loss of Sonic Hedgehog (Shh) and aberrant CDX2 expression are early changes correlating with the presence of intestinal metaplasia that occur in the gastric mucosa prior to neoplastic transformation. The aim of this study was to compare the improvement in corpus gastritis with Shh and CDX2 expression after H. pylori eradication between subjects at high risk for gastric cancer and controls. The usefulness of serum pepsinogen levels as a predictor of resolved corpus gastritis was also examined. Seventy patients with endoscopic resection for early gastric cancer and 30 controls were studied. Expression of Shh and CDX2 were evaluated by immunostaining. Serum levels of pepsinogen I before eradication in the patients scored as having improvement of corpus atrophy were significantly higher than in the patients without improvement (<0.01). Residual inflammation at the corpus lesser curve was more frequently detected in the cancer group than in the controls (OR 4.6 95% C.I. 1.6-13.5) and in the mucosa with incomplete intestinal metaplasia rather than in those without incomplete intestinal metaplasia (OR 7.6 95% C.I. 2.4-24.3). Atrophy, expression of Shh and CDX2 at the corpus lesser curve significantly improved in mucosa without incomplete intestinal metaplasia (p < 0.01), but not in mucosa with incomplete intestinal metaplasia. In conclusion, H. pylori eradication prior to development of incomplete intestinal metaplasia improves corpus gastritis and may prevent gastric cancer. Pepsinogen I may be a useful marker in patients with a residual higher risk of gastric cancer after H. pylori eradication.

Overexpression of CDX2 perturbs HOX gene expression in murine progenitors depending on its N-terminal domain and is closely correlated with deregulated HOX gene expression in human acute myeloid leukemia

The mechanisms underlying deregulation of HOX gene expression in AML are poorly understood. The ParaHox gene CDX2 was shown to act as positive upstream regulator of several HOX genes. In this study, constitutive expression of Cdx2 caused perturbation of leukemogenic Hox genes such as Hoxa10 and Hoxb8 in murine hematopoietic progenitors. Deletion of the N-terminal domain of Cdx2 abrogated its ability to perturb Hox gene expression and to cause acute myeloid leukemia (AML) in mice. In contrast inactivation of the putative Pbx interacting site of Cdx2 did not change the leukemogenic potential of the gene. In an analysis of 115 patients with AML, expression levels of CDX2 were closely correlated with deregulated HOX gene expression. Patients with normal karyotype showed a 14-fold higher expression of CDX2 and deregulated HOX gene expression compared with patients with chromosomal translocations such as t(8:21) or t(15;17). All patients with AML with normal karyotype tested were negative for CDX1 and CDX4 expression. These data link the leukemogenic potential of Cdx2 to its ability to dysregulate Hox genes. They furthermore correlate the level of CDX2 expression with HOX gene expression in human AML and support a potential role of CDX2 in the development of human AML with aberrant Hox gene expression.

Interaction of Toll-like receptors with bacterial components induces expression of CDX2 and MUC2 in rat biliary epithelium in vivo and in culture

The mechanism of transformation of biliary epithelium leading to intestinal metaplasia, which is significantly involved in biliary diseases, remains unclear. CDX2, an intestine-specific transcription factor, is thought to regulate intestinal mucin MUC2 (mucus core protein) expression. We took advantage of polycystic kidney (PCK) rats as a model of chronic suppurative cholangitis with intestinal metaplasia and of cultured biliary epithelial cells (BECs) from PCK rats to clarify the causal relation between bacterial components such as pathogen-associated molecular patterns (PAMPs) and the development of intestinal metaplasia of bile ducts. Histological, immunohistochemical, and in situ hybridization studies were conducted in PCK rat livers. In cultured BECs, CDX2 and MUC2 were expressed following treatment with PAMPs and inhibitors (anti-Toll-like receptor (TLR)2/TLR4 antibody, nuclear factor-kappaB (NF-kappaB) inhibitor MG132). Chronic suppurative cholangitis with intestinal metaplasia developed as the PCK rats aged, and intestinal metaplasia and aberrant CDX2 and MUC2 expression developed in parallel. Intraluminal bacteria and the expression of TLR2 and TLR4 in BECs were demonstrated in the bile ducts, showing chronic suppurative cholangitis. In cultured BECs, treatment with PAMPs induced upregulation of CDX2 and MUC2 expression, and this effect was abolished by pretreatment with anti-TLR2 and anti-TLR4 antibody and MG132. A knockdown of CDX2 by CDX2 small interfering RNA inhibited MUC2 expression in cultured BECs induced by PAMPs, and transfection of CDX2 expression vector induced MUC2 expression. In conclusion, bacterial components may induce upregulation of the CDX2 expression followed by MUC2 expression via TLR and the NF-kappaB system in cultured BECs, and could be related to the development of intestinal metaplasia of the bile ducts.

Gastric-and-intestinal mixed-type intestinal metaplasia: aberrant expression of transcription factors and stem cell intestinalization

Helicobacter pylori plays a causative role in the development of chronic atrophic gastritis, intestinal metaplasia (IM), and stomach cancer. Although IM has long attracted attention as a putative preneoplastic lesion for stomach cancers, its clinicopathologic significance has yet to be clarified in detail. Using gastric and intestinal epithelial cell markers, IM was here divided into two major types: a gastric-and-intestinal (GI) mixed type and a solely intestinal (I) type. In the former, gastric and intestinal phenotypic markers appeared not only at the glandular but also at the cellular level. Furthermore, neuroendocrine cells also showed intestinalization along with their exocrine counterparts. In animal models, GI-type IM was found to appear first, followed by the solely I type. Summarizing these data, it was suggested that IM might be caused by the gradual intestinalization of stem cells from the GI to the I type. The molecular mechanisms of IM include the ectopic expression of CDX1, CDX2, OCT-1, and members of the Erk pathway. Suppression of the expression of gastric transcription factors such as SOX2, genes that are involved in the Sonic hedgehog pathway, and RUNX3, a tumor suppressor gene, could be additional relevant alterations. The expression of PDX1 may also be associated with pseudopyloric gland metaplasia and IM. Detailed analysis of gene regulation may shed light on the molecular bases of gastric lesions, leading to strategies for chemoprevention.

Discussion on the reversibility of gastric intestinal metaplasia

Gastric intestinal metaplasia (IM), as precancerous lesion of the stomach, is closely associated with the development of gastric cancer. Whether gastric IM can be reversed is still in controversy. Epidemiological evidence showed that IM was reversible after long-term following up, but the reversed degree was low. Besides H pylori infection, deficiency of vitamin C in the gastric mucosa, shortage of gastric acid and/or bile reflux can cause this precancerous condition. The pathogenesis of gastric IM, in which H pylori virulence factors, intestine-specific transcription factors, and microsatellite instability are involved, is being investigated at the present time, but it can't be affirmed that IM is a kind of phenotype alteration in gastric epithelial cells induced by stem cell mutation. It is fairly difficult to make diagnosis for IM unless careful endoscopic evaluation is performed and proper biopsy sites are selected. Eradication of H pylori alone may not be enough to reverse IM, and its combination with other chemopreventive agents and/or Chinese medicine may be an effective strategy.

A close relationship between intestinal metaplasia and Cdx2 expression in human gallbladders with cholelithiasis

We previously reported a case of a human gallbladder with cholelithiasis consisting of intestinal metaplasia with the expression of caudal-related homeobox transcription factor (Cdx2). However, it is unclear how often intestinal metaplasia and Cdx2 expression occur in human, nontumorous gallbladders with cholelithiasis. We studied the incidence of intestinal metaplasia and Cdx2 expression in human gallbladders with cholelithiasis. Gallbladders were resected under laparoscopy from 103 patients with cholelithiasis between September 2003 and March 2005. The mean age of the patients was 59.6 +/- 15.0 years (range, 22-92 years). We retrospectively reviewed these cases to look for the presence of intestinal metaplasia and the expression of Cdx2. In addition, the characteristics of intestinal metaplasia were examined by immunostaining for Muc2, chromogranin A, and serotonin. Intestinal metaplasia was found in 11.7% (12/103) of the gallbladders with cholelithiasis. The mean ages of patients with and without intestinal metaplasia were 60.8 +/- 15.4 and 59.4 +/- 14.9 years, respectively. Cdx2, Muc2, chromogranin A, and serotonin were expressed in 91.7% (11/12), 91.7% (11/12), 83.3% (10/12), and 50.0% (6/12) in intestinal metaplastic mucosa, respectively. Only one case (1.1%) that expressed Cdx2 without intestinal metaplasia did not express Muc2, chromogranin A, and serotonin. We found that 10.7% (11/103) of nontumorous gallbladders resected because of cholelithiasis under laparoscopy revealed intestinal metaplasia with Cdx2 expression.

Helicobacter pylori-induced atrophic gastritis progressing to gastric cancer exhibits sonic hedgehog loss and aberrant CDX2 expression

BACKGROUND

The loss of sonic hedgehog is an early change that occurs in the mucosa prior to neoplastic transformation and correlates with the type of intestinal metaplasia. Aberrant expression of CDX has also been shown to correlate with the development of intestinal metaplasia.

AIM

To examine CDX2 expression in the non-cancerous mucosa of patients with gastric cancer and compared it to CDX2 expression in controls with intestinal metaplasia.

METHODS

Sixty patients who had undergone endoscopic mucosal resection for early gastric cancer and 60 gender- and age-matched controls were studied. Two specimens each were obtained from the greater and lesser curves of the corpus and from the greater curve of the antrum. Expression of CDX2 and sonic hedgehog were evaluated by immunostaining.

RESULTS

Gastric cancer was associated with a higher frequency of incomplete intestinal metaplasia (OR = 8.3; 95%CI, 3.7-18.9, P < 0.001). CDX2 negatively correlated with sonic hedgehog expression, however, multivariate analysis revealed that CDX2 correlated with the intestinal metaplasia scores. Sonic hedgehog indices were lower and CDX2 staining in the corpus lesser curve was higher in the cancer group than in the controls. Sonic hedgehog indices in the corpus decreased and CDX2 indices in both areas increased in patients in the ascending order of those without intestinal metaplasia, those with complete intestinal metaplasia and those with incomplete intestinal metaplasia (P < 0.001).

CONCLUSIONS

Loss of sonic hedgehog expression and aberrant expression of CDX2 correlates with the type of intestinal metaplasia and may play a role in carcinogenesis.

CDX2 does not suppress tumorigenicity in the human gastric cancer cell line MKN45

CDX2 is a Drosophila caudal-related homeobox transcription factor that is expressed specifically in the intestine. In mice, ectopic expression of CDX2 in the gastric mucosa gives rise to intestinal metaplasia and in one model, gastric carcinoma. In humans, increased CDX2 expression is associated with gastric intestinal metaplasia and tubular adenocarcinomas. These patterns of expression have shown that CDX2 is important for the initiation of intestinal metaplasia in the gastric mucosa, but the role of CDX2 in established gastric cancer remains unclear. We sought to determine whether CDX2 contributes to tumorigenic potential in established gastric cancer. The CDX2 gene in MKN45 gastric carcinoma cells was disrupted using targeted homologous recombination. The resulting CDX2-/- cells are essentially identical to their parental cells, with the exception of CDX2 ablation. We found no significant differences in the proliferation of CDX2-/- cells compared to CDX2+/+ cells, in vitro or in vivo. Molecular analyses show that loss of CDX2 predominantly altered the expression of genes involved in intestinal glandular differentiation and adhesion. However, there were no microscopic differences in tumor differentiation. We conclude that disruption of CDX2 in MKN45 cells does not significantly affect their tumorigenic potential.

Helicobacter pylori eradication to prevent gastric cancer: Underlying molecular and cellular mechanisms

Numerous cellular and molecular events have been described in development of gastric cancer. In this article, we overviewed roles of Helicobacter pylori (H pylori) infection on some of the important events in gastric carcinogenesis and discussed whether these cellular and molecular events are reversible after cure of the infection. There are several bacterial components affecting gastric epithelial kinetics and promotion of gastric carcinogenesis. The bacterium also increases risks of genetic instability and mutations due to NO and other reactive oxygen species. Epigenetic silencing of tumor suppressor genes such as RUNX3 may alter the frequency of phenotype change of gastric glands to those with intestinal metaplasia. Host factors such as increased expression of growth factors, cytokines and COX-2 have been also reported in non-cancerous tissue in H pylori-positive subjects. It is noteworthy that most of the above phenomena are reversed after the cure of the infection. However, some of them including overexpression of COX-2 continue to exist and may increase risks for carcinogenesis in metaplastic or dysplastic mucosa even after successful H pylori eradication. Thus, H pylori eradication may not completely abolish the risk for gastric carcinogenesis. Efficiency of the cure of the infection in suppressing gastric cancer depends on the timing and the target population, and warrant further investigation.