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

A Review of Therapeutic Effects and the Pharmacological Molecular Mechanisms of Chinese Medicine Weifuchun in Treating Precancerous Gastric Conditions

Patients with precancerous gastric conditions are at a high risk for gastric carcinoma. The Chinese medicine Weifuchun (WFC) is used in treating chronic superficial gastritis and in postoperative adjuvant treatment of gastric cancer. Both monotherapy and combination therapy of WFC with other drugs can result in a favorable therapeutic outcome. WFC can dramatically improve clinical outcomes in patients with gastric precancerous lesions by targeting multiple pathways including pathways involved in the pharmacological action of Radix Ginseng Rubra (red ginseng), Rabdosia amethystoides, and fried Fructus Aurantii, including regulation of NF-κB, RUNX3/TGF-beta/Smad, Hedgehog (Hh) and Wnt signaling pathways, modulation of the expression of oncogenes and tumor suppressor genes, and indirect inhibition of Helicobacter pylori (Hp) by maintaining gastric microbial ecosystem. In this review, we will discuss the clinical efficacy and therapeutic regimen of WFC for gastric precancerous lesions and the molecular mechanisms involved. This review will highlight WFC-based therapeutic strategies in disrupting progress to gastric cancer and provide more information on the pharmacological mechanisms of WFC and its clinical application for the treatment of precancerous gastric lesions.

Gastric cancer - histopathological correlations between tumor and non-tumor gastric mucosa changes

Gastric cancer is a widely geographically distributed malignancy with high prevalence, therefore being a serious health problem that needs standardized methods for early diagnosis and treatment. The aim of the study was to evaluate the correlation of some epidemiological and clinical data with the histological features. The study group was made up of 66 patients that underwent surgical removal of the gastric neoplasm, and the pathological exam showed the morphological features of the tumor, as well as the ones of the unaffected mucosal tissue. Topographically, the highest incidence of the tumor was registered in the gastric antrum, but in recent years, an increased incidence of the superior gastric pole localization was recorded. The macroscopic aspects reveal that the ulcerated type 2 Borrmann is the most frequent, and alongside type 3 Borrmann, the ulcer-infiltrative type represents most of the gastric antrum cancers. The analysis of the tumor invasion showed that most carcinomas underwent surgery when the tumor invaded the serosa (pT3) or even the perigastric tissues (pT4). In our research, we chose Goseki’s microscopic classification because of its best coverage of the histological heterogeneity of the gastric carcinomas, providing information about the percentage of the cellular and secretory differentiation with direct impact on the invasion of the tumor. In more than 70% of the cases, the patients showed lesions of severe chronic atrophic gastritis of the non-tumor mucosa. Lately, the incidence of Helicobacter pylori has been 5.5%, lower than indicated by mainstream literature. We observed that the incidence of type 3 incomplete intestinal metaplasia, as the most commonly involved factor in the etiopathogenesis of gastric neoplasms, was encountered in 36.3% of the cases, this percentage rising proportionally with age and being frequently associated with antrum tumors. In conclusion, the permanent analysis of the relation between epidemiological data and some histological features might be relevant for the characterization of the tumoral process or the non-tumor gastric mucosa, leading to an evaluation of the prognosis.

Phenotype characteristics of gastric epithelial mucus in patients with different gastric diseases: from superficial gastritis to gastric cancer

Background

Gastric gland mucin is important for maintaining the basic function of the gastric mucosa, protecting it from foreign substances and reducing the occurrence of gastric diseases. Exploring the phenotype of gastric gland mucus changes during the progression of gastric disease is of great clinical significance.

Methods

A total of 483 patients with different gastric diseases were collected in this study, including 82 superficial gastritis (SG), 81 atrophic gastritis (AG), 168 dysplasia (GD), and 152 gastric cancer (GC). Mucin staining was performed using HID-ABpH2.5-PAS method and was further grouped according to the mucin coloration.

Results

The phenotypic characteristics of mucin during disease progression were divided into neutral, acidic, and mucus-free types. Furthermore, acidic mucus can be divided into type I, type II, and type III. The SG group was dominated by neutral mucus (100%), and the AG was dominated by acid mucus (81.48%), which gradually increased with the severity of atrophy (P < 0.05). The GD and GC groups were dominated by mucus-free (43.45%, 78.29%), and as the degree of GD worsened, neutral and acidic mucus gradually decreased and mucus-free increased (P < 0.001). From the SG, AG, GD, and GC progression, neutral and acidic mucus gradually decreased, and mucus- free gradually increased. Acidic mucin revealed that type III (red-brown black) mucin was predominant in AG, GD, and GC, and increased with the degree of AG, GD, as well as the biological behavior of GC. In the lesion adjacent to high-grade GD or GC, type III acid mucin is predominant.

Conclusion

There were three mucin phenotypes in the process of gastric diseases. With the disease progression, the trend of phenotypic change was that neutral and acidic mucus gradually decreased and mucus-free increased. The appearance of type III mucin suggested a relatively serious phase of gastric diseases and may be a more suitable candidate for follow-up monitoring of patients with GC risk.

Occurrence of gastric cancer in patients with atrophic gastritis during long-term follow-up

BACKGROUND

Additional data on the incidence of gastric neoplasia in the Chinese atrophic gastritis (AG) population during long-term follow-up are needed and the influence of the endoscopic surveillance interval on gastric neoplasia occurrence remains unknown.

AIMS

Retrospectively investigated the occurrence of gastric cancer (GC) and precancerous lesions in AG patients during long-term follow-up and assessed risk factors, such as the endoscopic surveillance interval for the development of gastric neoplasia.

METHODS

This study enrolled 332 AG patients who underwent initial gastroscopy from 2002 to 2005. Following parameters were collected: age, gender, smoking history, H. pylori infection, location of atrophy and intestinal metaplasia (IM), surveillance interval, follow-up duration, and neoplasia occurrence.

RESULTS

Gastric neoplasia was diagnosed in 16 patients. The annual incidence rates per person-year of total gastric neoplasia, gastric high-grade intraepithelial neoplasia (HGIN), early GC and advanced GC were 0.53%, 0.07%, 0.20% and 0.33%, respectively. A multivariate Cox analysis not accounting for the extent of AG and/or IM showed that the risk factors for GC development among AG patients included the presence of AG and/or IM involving both antral and corporal (p<.001, HR 2.898) and H. pylori infection (p=.018, HR 3.946). In the extensive AG and/or IM group, a 2- to 3-year surveillance interval might be instructive in early detection of GC (p=.008, HR 0.015).

CONCLUSIONS

Our data reveal an annual incidence rate of 0.53% per person-year for GC and HGIN in AG patients. A 2- to 3-year surveillance interval may be suitable for patients with extensive AG and/or IM.

The evolving role of endoscopy in the diagnosis of premalignant gastric lesions

Gastric adenocarcinoma is a disease that is often detected late, at a stage when curative treatment is unachievable. This must be addressed through changes in our approach to the identification of patients at increased risk by improving the detection and risk assessment of premalignant changes in the stomach, including chronic atrophic gastritis and intestinal metaplasia. Current guidelines recommend utilising random biopsies in a pathology-led approach in order to stage the extent and severity of gastritis and intestinal metaplasia. This random method is poorly reproducible and prone to sampling error and fails to acknowledge recent advances in our understanding of the progression to gastric cancer as a non-linear, branching evolutionary model. Data suggest that recent advances in endoscopic imaging modalities, such as narrow band imaging, can achieve a high degree of accuracy in the stomach for the diagnosis of these premalignant changes. In this review, we outline recent data to support a paradigm shift towards an endoscopy-led approach to diagnosis and staging of premalignant changes in the stomach. High-quality endoscopic interrogation of the chronically inflamed stomach mucosa, supported by targeted biopsies, will lead to more accurate risk assessment, with reduced rates of under or missed diagnoses.

COX-2 gene expression and methylation profile in Sapajus apella as an experimental model for gastric adenocarcinoma

Gastric cancer (GC) remains one of the main causes of cancer-related death worldwide. There are two distinct histological types of GC: diffuse and intestinal. The latter is characterized by the presence of pre-neoplastic lesions. One of the most frequently altered enzymes in intestinal GC is COX-2, an important lesion marker. This work aimed to study COX-2 methylation and expression in N-methyl-N-Nitrosurea (MNU)-induced intestinal GC in six Sapajus apella animals. The partial promoter sequence of S. apella COX-2 gene was obtained and used to identify transcription factors and cis-regulatory element binding sites. The COX-2 methylation pattern was assessed using Methylation-Specific PCR (MSP), and expression was analyzed by immunohistochemistry (IHQ). A total of 20 samples were obtained. A 675 bp fragment of the S. apella COX-2 promoter region was obtained, and it was 99.2% and 68.2% similar to H. sapiens and S. boliviensis, respectively. Similar to humans, several transcription factors and cis-regulatory element binding sites were identified in the S. apella sequence. MSP revealed that all samples were methylated. However, IHQ results demonstrated positive COX-2 expression in all pre-neoplastic and tumoral samples. The results suggest that the analyzed fragment is not crucial in COX-2 regulation of GC in S. apella.

Metaplasia: tissue injury adaptation and a precursor to the dysplasia-cancer sequence

Metaplasia is the replacement of one differentiated somatic cell type with another differentiated somatic cell type in the same tissue. Typically, metaplasia is triggered by environmental stimuli, which may act in concert with the deleterious effects of microorganisms and inflammation. The cell of origin for intestinal metaplasia in the oesophagus and stomach and for pancreatic acinar-ductal metaplasia has been posited through genetic mouse models and lineage tracing but has not been identified in other types of metaplasia, such as squamous metaplasia. A hallmark of metaplasia is a change in cellular identity, and this process can be regulated by transcription factors that initiate and/or maintain cellular identity, perhaps in concert with epigenetic reprogramming. Universally, metaplasia is a precursor to low-grade dysplasia, which can culminate in high-grade dysplasia and carcinoma. Improved clinical screening for and surveillance of metaplasia might lead to better prevention or early detection of dysplasia and cancer.

miR-30-HNF4γ and miR-194-NR2F2 regulatory networks contribute to the upregulation of metaplasia markers in the stomach

OBJECTIVE

Intestinal metaplasia and spasmolytic polypeptide-expressing metaplasia (SPEM) are considered neoplastic precursors of gastric adenocarcinoma and are both marked by gene expression alterations in comparison to normal stomach. Since miRNAs are important regulators of gene expression, we sought to investigate the role of miRNAs on the development of stomach metaplasias.

DESIGN

We performed miRNA profiling using a quantitative reverse transcription-PCR approach on laser capture microdissected human intestinal metaplasia and SPEM. Data integration of the miRNA profile with a previous mRNA profile from the same samples was performed to detect potential miRNA-mRNA regulatory circuits. Transfection of gastric cancer cell lines with selected miRNA mimics and inhibitors was used to evaluate their effects on the expression of putative targets and additional metaplasia markers.

RESULTS

We identified several genes as potential targets of miRNAs altered during metaplasia progression. We showed evidence that HNF4γ (upregulated in intestinal metaplasia) is targeted by miR-30 and that miR-194 targets a known co-regulator of HNF4 activity, NR2F2 (downregulated in intestinal metaplasia). Intestinal metaplasia markers such as VIL1, TFF2 and TFF3 were downregulated after overexpression of miR-30a in a HNF4γ-dependent manner. In addition, overexpression of HNF4γ was sufficient to induce the expression of VIL1 and this effect was potentiated by downregulation of NR2F2.

CONCLUSIONS

The interplay of the two transcription factors HNF4γ and NR2F2 and their coordinate regulation by miR-30 and miR-194, respectively, represent a miRNA to transcription factor network responsible for the expression of intestinal transcripts in stomach cell lineages during the development of intestinal metaplasia.

[Continual self-renewal of the gastric epithelium by cell differentiation: implications for carcinogenesis]

BACKGROUND

The gastric mucosa and its glands represent a close interactive barrier to the outside world. This delicate surface is protected by a multilayered mucus barrier which contains among others the mucins MUC5AC and MUC6 and the trefoil factor family peptide TFF2. Furthermore, two types of gastric glands form delicate homeostatic systems, i.e. the fundic and antral glands, which show continual bidirectional self-renewal via differentiation from stem and progenitor cells. It was the aim of this study to analyze the self-renewal of these gastric units.

MATERIAL AND METHODS

Three characteristic regions (i.e. foveolar, proliferative zone and lower gland regions) were isolated from fundic and antral units by the use of laser microdissection and expression profiles concerning known marker genes were generated by reverse transcription polymerase chain reaction (RT-PCR) analysis.

RESULTS

The surface mucous cells (SMCs) of fundic and antral units characteristically differed in the expression of certain secretory genes. Furthermore, the maturation of mucous neck cells and their trans-differentiation into chief cells as well as the maturation of antral SMCs and antral gland cells occurred in a stepwise manner.

DISCUSSION

The correct maturation particularly of mucous neck cells and their trans-differentiation into chief cells is critical for homeostatic self-renewal of fundic units. Dysregulation of this multistep process can result in generation of the spasmolytic polypeptide-expressing metaplasia (SPEM) lineage which is characterized by its strong ectopic TFF2 expression. Chronic inflammation is known to support SPEM formation. The SPEM lineage is a precancerous lesion which can further differentiate into intestinal metaplasia.

Intestinal metaplasia and anastomotic recurrence of gastric carcinoma

Intestinal metaplasia (IM) of the stomach has been shown to increase the relative risk of gastric cancer. Endoscopic surveillance has been proposed and advocated for populations at risk. Those patients who had undergone surgery for gastric malignancy exhibited precancerous lesions such as atrophic gastritis and IM, and the possibility of anastomotic recurrence is higher than for the patients who had undergone benign gastric surgery. At present, there are no other recognized good markers of gastric dysplasia or cancer. We reviewed the literature on IM of the stomach to ascertain whether residual premalignant (type III) IM may predispose to anastomotic recurrence of gastric cancer.

Screening for and surveillance of gastric cancer

Although the prevalence of gastric cancer (GC) progressively decreased during the last decades, due to improved dietary habit, introduction of food refrigeration and recovered socio-economic level, it still accounts for 10% of the total cancer-related deaths. The best strategy to reduce the mortality for GC is to schedule appropriate screening and surveillance programs, that rises many relevant concerns taking into account its worldwide variability, natural history, diagnostic tools, therapeutic strategies, and cost-effectiveness. Intestinal-type, the most frequent GC histotype, develops through a multistep process triggered by Helicobacter pylori (H. pylori) and progressing from gastritis to atrophy, intestinal metaplasia (IM), and dysplasia. However, the majority of patients infected with H. pylori and carrying premalignant lesions do not develop GC. Therefore, it remains unclear who should be screened, when the screening should be started and how the screening should be performed. It seems reasonable that screening programs should target the general population in eastern countries, at high prevalence of GC and the high-risk subjects in western countries, at low prevalence of GC. As far as concern surveillance, currently, we are lacking of standardized international recommendations and many features have to be defined regarding the optimal diagnostic approach, the patients at higher risk, the best timing and the cost-effectiveness. Anyway, patients with corpus atrophic gastritis, extensive incomplete IM and dysplasia should enter a surveillance program. At present, screening and surveillance programs need further studies to draw worldwide reliable recommendations and evaluate the impact on mortality for GC.

Secondary prevention of epidemic gastric cancer in the model of Helicobacter pylori-associated gastritis

Irrespective of its etiology, long-standing, non-self-limiting gastric inflammation (mostly in Helicobacter pylori-associated cases) is the cancerization ground on which epidemic (intestinal-type) gastric carcinoma (GC) can develop. The natural history of invasive gastric adenocarcinoma encompasses gastritis, atrophic mucosal changes, and intraepithelial neoplasia (IEN). The topography, the extent and the severity of the atrophic changes significantly correlate with the risk of developing both IEN and GC. In recent years, both noninvasive (serological) tests and invasive (endoscopy/biopsy) procedures have been proposed to stratify patients according to different classes of GC risk. As a consequence, different patient-tailored GC secondary prevention strategies have been put forward. This review summarizes the histological features of H. pylori-related gastritis and the natural history of the disease. Histological and serological strategies to assess GC risk as well as the clinical management of atrophic gastritis patients are also discussed.

The role of inflammation in gastric cancer

Gastric cancer, despite its declining incidence rate, is still the second cause of cancer-related death worldwide, killing 750,000 people each year and remaining the second common type of cancer. The best examples of inflammation-associated cancer in human beings may be gastric cancer. Understanding the molecular mechanism of the inflammation in gastric carcinogenesis is important for developing new strategies against gastric cancer.

CDX1 confers intestinal phenotype on gastric epithelial cells via induction of stemness-associated reprogramming factors SALL4 and KLF5

Intestinal metaplasia of the stomach, a mucosal change characterized by the conversion of gastric epithelium into an intestinal phenotype, is a precancerous lesion from which intestinal-type gastric adenocarcinoma arises. Chronic infection with Helicobacter pylori is a major cause of gastric intestinal metaplasia, and aberrant induction by H. pylori of the intestine-specific caudal-related homeobox (CDX) transcription factors, CDX1 and CDX2, plays a key role in this metaplastic change. As such, a critical issue arises as to how these factors govern the cell- and tissue-type switching. In this study, we explored genes directly activated by CDX1 in gastric epithelial cells and identified stemness-associated reprogramming factors SALL4 and KLF5. Indeed, SALL4 and KLF5 were aberrantly expressed in the CDX1(+) intestinal metaplasia of the stomach in both humans and mice. In cultured gastric epithelial cells, sustained expression of CDX1 gave rise to the induction of early intestinal-stemness markers, followed by the expression of intestinal-differentiation markers. Furthermore, the induction of these markers was suppressed by inhibiting either SALL4 or KLF5 expression, indicating that CDX1-induced SALL4 and KLF5 converted gastric epithelial cells into tissue stem-like progenitor cells, which then transdifferentiated into intestinal epithelial cells. Our study places the stemness-related reprogramming factors as critical components of CDX1-directed transcriptional circuitries that promote intestinal metaplasia. Requirement of a transit through dedifferentiated stem/progenitor-like cells, which share properties in common with cancer stem cells, may underlie predisposition of intestinal metaplasia to neoplastic transformation.

Gastric carcinogenesis

Gastric cancer is the second most common cancer worldwide and the second most common cause of cancer-related deaths. Despite complete resection of gastric cancer and lymph node dissection, as well as improvements in chemotherapy and radiotherapy, there are still 700 000 gastric cancer-related deaths per year worldwide and more than 80% of patients with advanced gastric cancer die of the disease or recurrent disease within 1 year after diagnosis. None of the treatment modalities we have been applying today can influence the overall survival rates: at present, the overall 5-year relative survival rate for gastric cancer is about 28%. Cellular metaplasia due to chronic inflammation, injury and repair are the most documented processes for neoplasia. It appears that chronic inflammation stimulates tumor development and plays a critical role in initiating, sustaining and advancing tumor growth. It is also evident that not all inflammation is tumorigenic. Additional mutations can be acquired, and this leads to the cancer cell gaining a further growth advantage and acquiring a more malignant phenotype. Intestinalization of gastric units, which is called “intestinal metaplasia”; phenotypic antralization of fundic units, which is called “spasmolytic polypeptide-expressing metaplasia”; and the development directly from the stem/progenitor cell zone are three pathways that have been described for gastric carcinogenesis. Also, an important factor for the development of gastrointestinal cancers is peritumoral stroma. However, the initiating cellular event in gastric metaplasia is still controversial. Understanding gastric carcinogenesis and its precursor lesions has been under intense investigation, and our paper attempts to highlight recent progress in this field of cancer research.

Epigenetic regulation of Delta-Like1 controls Notch1 activation in gastric cancer

The Notch signaling pathway drives proliferation, differentiation, apoptosis, cell fate, and maintenance of stem cells in several tissues. Aberrant activation of Notch signaling has been described in several tumours and in gastric cancer (GC), activated Notch1 has been associated with de-differentiation of lineage-committed stomach cells into stem progenitors and GC progression. However, the specific role of the Notch1 ligand (DLL1) in GC has not yet been elucidated. To assess the role of DLL1 in GC cancer, the expression of Notch1 and its ligands DLL1 and Jagged1, was analyzed in 8 gastric cancer cell lines (KATOIII, SNU601, SNU719, AGS, SNU16, MKN1, MKN45, TMK1). DLL1 expression was absent in KATOIII, SNU601, SNU719 and AGS. The lack of DLL1 expression in these cells was associated with promoter hypermethylation and 5-aza-2’deoxycitidine caused up-regulation of DLL1. The increase in DLL1 expression was associated with activation of Notch1 signalling, with an increase in cleaved Notch1 intracellular domain (NICD) and Hes1, and down-regulation in Hath1. Concordantly, Notch1 signalling was activated with the overexpression of DLL1. Moreover, Notch1 signalling together with DLL1 methylation were evaluated in samples from 52 GC patients and 21 healthy control as well as in INS-GAS mice infected with H. pylori and randomly treated with eradication therapy. In GC patients, we found a correlation between DLL1 and Hes1 expression, while DLL1 methylation and Hath1 expression were associated with the diffuse and mixed type of gastric cancer. Finally, none of the samples from INS-GAS mice infected with H. pylori, a model of intestinal-type gastric tumorigenesis, showed promoter methylation of DLL1. This study shows that Notch1 activity in gastric cancer is controlled by the epigenetic silencing of the ligand DLL1, and that Notch1 inhibition is associated with the diffuse type of gastric cancer.

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.

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.

Operative link for gastritis assessment vs operative link on intestinal metaplasia assessment

AIM: To compare the reliability of gastritis staging systems in ranking gastritis-associated cancer risk in a large series of consecutive patients.

METHODS: Gastric mucosal atrophy is the precancerous condition in which intestinal-type gastric cancer (GC) most frequently develops. The operative link for gastritis assessment (OLGA) staging system ranks the GC risk according to both the topography and the severity of gastric atrophy (as assessed histologically on the basis of the Sydney protocol for gastric mucosal biopsy). Both cross-sectional and long-term follow-up trials have consistently associated OLGA stages III-IV with a higher risk of GC. A recently-proposed modification of the OLGA staging system (OLGIM) basically incorporates the OLGA frame, but replaces the atrophy score with an assessment of intestinal metaplasia (IM) alone. A series of 4552 consecutive biopsy sets (2007-2009) was retrieved and reassessed according to both the OLGA and the OLGIM staging systems. A set of at least 5 biopsy samples was available for all the cases considered.

RESULTS: In 4460 of 4552 cases (98.0%), both the high-risk stages (III + IV) and the low-risk stages (0 +I + II) were assessed applying the OLGA and OLGIM criteria. Among the 243 OLGA high-risk stages, 14 (5.8%) were down-staged to a low risk using OLGIM. The 67 (1.5%) incidentally-found neoplastic lesions (intraepithelial or invasive) were consistently associated with high-risk stages, as assessed by both OLGA and OLGIM (P < 0.001 for both). Two of 34 intestinal-type GCs coexisting with a high-risk OLGA stage (stage III) were associated with a low-risk OLGIM stage (stage II).

CONCLUSION: Gastritis staging systems (both OLGA and OLGIM) convey prognostically important information on the gastritis-associated cancer risk. Because of its clinical impact, the stage of gastritis should be included as a conclusive message in the gastritis histology report. Since it focuses on IM alone, OLGIM staging is less sensitive than OLGA staging in the identification of patients at high risk of gastric cancer.

Gastritis: the histology report

Gastritis is defined as inflammation of the gastric mucosa. In histological terms, it is distinguishable into two main categories, i.e. non-atrophic and atrophic. In the gastric mucosa, atrophy is defined as the loss of appropriate glands. There are several etiological types of gastritis, their different etiology being related to different clinical manifestations and pathological features. Atrophic gastritis (resulting mainly from long-standing Helicobacter pylori infection) is a major risk factor for the onset of (intestinal type) gastric cancer. The extent and site of the atrophic changes correlate significantly with the cancer risk. The current format for histology reporting in cases of gastritis fails to establish an immediate link between gastritis phenotype and risk of malignancy. Building on current knowledge of the biology of gastritis, an international group of pathologists [Operative Link for Gastritis Assessment (OLGA)] has proposed a system for reporting gastritis in terms of its stage (the OLGA Staging System): this system places the histological phenotypes of gastritis on a scale of progressively increasing gastric cancer risk, from the lowest (Stage 0) to the highest (Stage IV). The aim of this tutorial is to provide unequivocal information on how to standardize histology reports on gastritis in diagnostic practice.

A comparison of primary oesophageal squamous epithelial cells with HET-1A in organotypic culture

BACKGROUND INFORMATION

Carcinoma of the oesophagus is the sixth leading cause of cancer death in the western world and is associated with a 5-year survival of less than 15%. Recent evidence suggests that stromal-epithelial interactions are fundamental in carcinogenesis. The advent of co-culture techniques permits the investigation of cross-talk between the stroma and epithelium in a physiological setting. We have characterized a histologically representative oesophageal organotypic model and have used it to compare the most commonly used squamous oesophageal cell line, HET-1A, with primary oesophageal squamous cells for use in studies of the oesophageal epithelium in vitro.

RESULTS

When grown in an organotypic culture with normal fibroblasts, the oesophageal carcinoma cell lines OE21 (squamous) and OE19 (adenocarcinoma) morphologically resembled the tumour of origin with evidence of stromal invasion and mucus production, respectively. However, HET-1A cells, which were derived from normal squamous oesophageal cells, appeared dysplastic and failed to display evidence of squamous differentiation. By comparison with primary oesophageal epithelial cells, the HET-1A cells were highly proliferative and did not express the epithelial markers E-cadherin or CK5/6 (casein kinase 5/6), or the stratified epithelial marker ΔNp63, but did express the mesenchymal markers vimentin and N-cadherin.

CONCLUSION

Studies of epithelial carcinogenesis will benefit from culture systems which allow manipulation of the stromal and epithelial layers independently. We have developed an organotypic culture using primary oesophageal squamous cells and fibroblasts in which a stratified epithelium with a proliferative basal layer that stains strongly for ΔNp63 develops. This model will be suitable for the study of the molecular events in the development of Barrett's oesophagus. The most commonly used normal oesophageal squamous cell line, HET-1A, does not have the characteristics of normal oesophageal squamous cells and should not be used in models of the normal oesophageal epithelium. Until more representative cell lines are available, future studies in oesophageal cancer will be reliant on the availability and manipulation of primary tissue.

Expression of TERT in precancerous gastric lesions compared to gastric cancer

The objective of this study was to determine the levels of TERT mRNA and TERT protein expression in stomach precancerous lesions such as intestinal metaplasia (IM) and gastric ulcer (GU) and compare them to gastric cancer (GC). Real-time PCR was performed to detect TERT mRNA expression levels in 35 biopsies of IM, 30 of GU, and 22 of GC and their respective normal mucosas. TERT protein was detected by immunohistochemistry in 68 samples, 34 of IM, 23 of GU, and 11 of GC. Increased TERT mRNA expression levels were observed in a significant number of cases, i.e., 46% of IM, 50% of GU, and 79% of GC. The relative mean level of TERT mRNA after normalization with the β-actin reference gene and comparison with the respective adjacent normal mucosa was slightly increased in the IM and GU groups, 2.008 ± 2.605 and 2.730 ± 4.120, respectively, but high TERT mRNA expression was observed in the GC group (17.271 ± 33.852). However, there were no statistically significant differences between the three groups. TERT protein-positive immunostaining was observed in 38% of IM, 39% of GU, and 55% of GC. No association of TERT mRNA and protein expression with Helicobacter pylori infection or other clinicopathological variables was demonstrable, except for the incomplete type vs the complete type of IM. This study confirms previous data of the high expression of both TERT mRNA and protein in gastric cancer and also demonstrates this type of changed expression in IM and GU, thus suggesting that TERT expression may be deregulated in precursor lesions that participate in the early stages of gastric carcinogenesis.

Gene expression profiling of metaplastic lineages identifies CDH17 as a prognostic marker in early stage gastric cancer

BACKGROUND & AIMS

Intestinal metaplasia (IM) and spasmolytic polypeptide-expressing metaplasia (SPEM) are precursors to gastric carcinogenesis. We sought to identify molecular biomarkers of gastric metaplasias and gastric cancer by gene expression profiling of metaplastic lesions from patients.

METHODS

Complementary DNA microarray analysis was performed on IM and SPEM cells isolated from patient samples using laser capture microdissection. Up-regulated transcripts in metaplastic lesions were confirmed by immunostaining analysis in IM, SPEM, and gastric cancer tissues. Proteins that were highly expressed specifically in gastric cancer tissues were analyzed for their association with survival in a test set (n = 450) and a validation set (n = 502) of samples from gastric cancer patients.

RESULTS

Compared with normal chief cells, 858 genes were differentially expressed in IM or SPEM samples. Immunostaining was detected for 12 proteins, including 3 new markers of IM (ACE2, LGALS4, AKR1B10) and 3 of SPEM (OLFM4, LYZ, DPCR1). Of 13 proteins expressed in IM or SPEM, 8 were expressed by 17%-50% of human gastric cancer tissues (MUC13, OLFM4, CDH17, KRT20, MUC5AC, LGALS4, AKR1B10, REG4). Expression of CDH17 or MUC13 correlated with patient survival in the test and validation sets. Multivariate analysis showed that CDH17 was an independent prognostic factor in patients with stage I or node-negative disease.

CONCLUSIONS

We identified several novel biomarkers for IM, SPEM, and gastric cancer using gene expression profiling of human metaplastic lesions. Expression of CDH17 and MUC13 was up-regulated in gastric cancer tissues. CDH17 is a promising prognostic marker for early stage gastric cancer.

Impaired gastric gland differentiation in Peutz-Jeghers syndrome

Gastrointestinal hamartomatous polyps in the Peutz-Jeghers cancer predisposition syndrome and its mouse model (Lkb1(+/-)) are presumed to contain all cell types native to the site of their occurrence. This study aimed to explore the pathogenesis of Peutz-Jeghers syndrome polyposis by characterizing cell types and differentiation of the epithelium of gastric polyps and predisposed mucosa. Both antral and fundic polyps were characterized by a deficit of pepsinogen C-expressing differentiated gland cells (antral gland, mucopeptic, and chief cells); in large fundic polyps, parietal cells were also absent. Gland cell loss was associated with an increase in precursor neck cells, an expansion of the proliferative zone, and an increase in smooth muscle alpha-actin expressing myofibroblasts in the polyp stroma. Lack of pepsinogen C-positive gland cells identified incipient polyps, and even the unaffected mucosa of young predisposed mice displayed an increase in pepsinogen C negative glands (25%; P = 0045). In addition, in small intestinal polyps, gland cell differentiation was defective, with the absence of Paneth cells. There were no signs of metaplastic differentiation in any of the tissues studied, and both the gastric and small intestinal defects were seen in Lkb1(+/-) mice, as well as polyps from patients with Peutz-Jeghers syndrome. These results identify impaired epithelial differentiation as the earliest pathological sign likely to contribute to tumorigenesis in individuals with inherited Lkb1 mutations.

Early events during neoplastic progression in Barrett's esophagus

Barrett's esophagus is a condition in which the stratified squamous epithelium of the distal esophagus is replaced by specialized intestinal metaplasia. Clinical management of Barrett's esophagus, like many other "premalignant" conditions, is characterized by overdiagnosis of benign early changes that will not cause death or suffering during the lifetime of an individual and underdiagnosis of life-threatening early disease. Recent studies of a number of different types of cancer have revealed much greater genomic complexity than was previously suspected. This genomic complexity could create challenges for early detection and prevention if it develops in premalignant epithelia prior to cancer. Neoplastic progression unfolds in space and time, and Barrett's esophagus provides one of the best models for rapid advances, including "gold standard" cohort studies, to distinguish individuals who do and do not progress to cancer. Specialized intestinal metaplasia has many properties that appear to be protective adaptations to the abnormal environment of gastroesophageal reflux. A large body of evidence accumulated over several decades implicates chromosome instability in neoplastic progression from Barrett's esophagus to esophageal adenocarcinoma. Small, spatial scale studies have been used to infer the temporal order in which genomic abnormalities develop during neoplastic progression in Barrett's esophagus. These spatial studies have provided the basis for prospective cohort studies of biomarkers, including DNA content abnormalities (tetraploidy, aneuploidy) and a biomarker panel of 9p LOH, 17p LOH and DNA content abnormalities. Recent advances in SNP array technology provide a uniform platform to assess chromosome instability.

Relationship between TFF3 expression and gastric cardiac carcinogenesis

AIM: To explore the relationship between the expression of trefoil factor 3 (TFF3) protein and the evolution of gastric cardiac adenocarcinoma.

METHODS: The streptavidin-peroxidase immunohistochemistry method was used to detect TFF3 protein expression in 24 cardiac gastritis specimens, 52 intestinal metaplasia specimens, 65 specimens of intestinal metaplasia with dysplasia and 35 gastric cardiac adenocarcinoma specimens from a high incidence area of gastric cardiac adenocarcinoma in Henan.

RESULTS: TFF3 protein is predominantly expressed in the striated border of the columnar cells in cardiac gastritis and intestinal metaplasia tissues, and in the cytoplasm in dysplasia and carcinoma tissues. The positive rates of TFF3 protein in cardiac gastritis, intestinal metaplasia, dysplasia, and carcinoma tissues were 20.8%, 44.2%, 46.2% and 54.3%, respectively. The expression of TFF3 was correlated well with the pathological grade of the lesions (r = 0.232, P < 0.05). The location of TFF3 expression was correlated with the pathological types of the lesions (Kappa = 0.490).

CONCLUSION: Overexpression of TFF3 protein in the cytoplasm is involved in gastric cardiac carcinogenesis and might be one of important risk factors for gastric cardiac adenocarcinoma.

Intestinal metaplasia in liver of rats after partial hepatectomy and treatment with acetylaminofluorene

OBJECTIVES

The liver is widely recognized for its ability to self-regenerate after damage. Hepatocyte replication is the primary source of liver restoration, although hepatic stem cells (of one kind or another) may be a secondary font, only brought into effect when primary regeneration is severely compromised.

MATERIALS AND METHODS

In experiments using small rodents, such an injury can be inflicted by surgically removing a large portion of the liver followed by treatment with hepatotoxin 2-acetylaminofluorene. Regeneration by hepatocyte replication is blocked and thus, stem cell involvement is promoted. However, other responses may be stimulated and this study describes the presence of mucinous glandular structures in the healing liver after two-thirds of its volume was removed via hepatectomy followed by treatment with 2-acetylaminofluorene.

RESULTS

Unique observation of intestinal metaplastic cells was seen under alcian blue/periodic acid-Schiff staining.

CONCLUSION

The existence of this phenotype (along with oval cells and small hepatocyte-like cells) is evidence of multipotency of progenitors involved in the hepatic healing response.

Gastrointestinal differentiation marker Cytokeratin 20 is regulated by homeobox gene CDX1

CDX1 is a transcription factor that plays a key role in intestinal development and differentiation. However, the downstream targets of CDX1 are less well defined than those of its close homologue, CDX2. We report here the identification of downstream targets of CDX1 using microarray gene-expression analysis and other approaches. Keratin 20 (KRT20), a member of the intermediate filament and a well-known marker of intestinal differentiation, was initially identified as one of the genes likely to be directly regulated by CDX1. CDX1 and KRT20 mRNA expression were significantly correlated in a panel of 38 colorectal cancer cell lines. Deletion and mutation analysis of the KRT20 promoter showed that the minimum regulatory region for the control of KRT20 expression by CDX1 is within 246 bp upstream of the KRT20 transcription start site. ChIP analysis confirmed that CDX1 binds to the predicted CDX elements in this region of the KRT20 promoter in vivo. In addition, immunohistochemistry showed expression of CDX1 parallels that of KRT20 in the normal crypt, which further supports their close relationship. In summary, our observations strongly imply that KRT20 is directly regulated by CDX1, and therefore suggest a role for CDX1 in maintaining differentiation in intestinal epithelial cells. Because a key feature of the development of a cancer is an unbalanced program of proliferation and differentiation, dysregulation of CDX1 may be an advantage for the development of a colorectal carcinoma. This could, therefore, explain the relatively frequent down regulation of CDX1 in colorectal carcinomas by hypermethylation.