Metaplasia as a premalignant pathology in the stomach

Longer examination time improves detection of gastric cancer during diagnostic upper gastrointestinal endoscopy

BACKGROUND & AIMS

It is not clear how the duration of upper endoscopy affects the detection of cancer or premalignant lesions that increase the risk for gastric cancer. We investigated whether the length of time spent performing esophagogastroduodenoscopy (EGD) affects the detection of important pathologic features of the stomach.

METHODS

We collected data from 837 symptomatic patients, during a 3-month period in 2010, who underwent a first diagnostic EGD at a tertiary university hospital in Singapore. Endoscopists were classified as fast or slow based on the mean amount of time it took them to perform a normal EGD examination. We used logistic regression to compare between groups the numbers of intestinal metaplasias, gastric atrophies, dysplasias, and cancers detected, using histologic analysis of biopsy samples collected during endoscopy as the standard.

RESULTS

Of 224 normal endoscopies, the mean duration was 6.6 minutes (range, 2-32 min). When we used 7 minutes as the cut-off time, 8 endoscopists were considered to have short mean examination times (mean duration, 5.5 ± 2.1 min; referred to as fast endoscopists), and 8 endoscopists were considered to have long mean examination times (mean duration, 8.6 ± 4.2 min; referred to as slow endoscopists). Eleven cancers and 81 lesions considered to pose risks for cancer were detected in 86 patients; 1.3% were determined to be cancer, 1.0% were determined to be dysplasia, and 8.7% were determined to be intestinal metaplasia and/or gastric atrophy. Slow endoscopists were twice as likely to detect high-risk lesions as fast endoscopists (odds ratio, 2.50; 95% confidence interval, 1.52-4.12), regardless of whether they were endoscopy staff or trainees. The slow endoscopists also detected 3-fold more neoplastic lesions (cancer or dysplasia; odds ratio, 3.42; 95% confidence interval, 1.25-10.38).

CONCLUSIONS

Endoscopists with mean EGD examination times longer than 7 minutes identified a greater number of high-risk gastric lesions than faster endoscopists. Examination time may be a useful indicator of quality assessment for upper endoscopy. Studies are required to test these findings in different populations.

Significance of expression of Sox2 and Cdx2 in gastric intestinal metaplasia

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

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

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

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

Inducible activation of Cre recombinase in adult mice causes gastric epithelial atrophy, metaplasia, and regenerative changes in the absence of "floxed" alleles

The epithelium of the mammalian gastric body comprises multiple cell types replenished by a single stem cell. The adult conformation of cell lineages occurs well after birth; hence, study of genes regulating stem cell activity is facilitated by inducible systems for gene deletion. However, there is a potential pitfall involving the commonly used inducible Cre recombinase system to delete genes: we report here that induction of Cre using standard doses of tamoxifen led to marked spasmolytic polypeptide-expressing metaplasia of the stomach within days and profound atrophy of the entire epithelium with foci of hyperplasia by 2 wk even in the absence of loxP-flanked alleles. Cre induction caused genotoxicity with TdT-mediated dUTP nick-end labeling (TUNEL)-positive apoptosis (TUNEL-positive cells) and increased levels of DNA damage markers (gammaH2AX, p53, DDIT3, GADD45A). Although Cre was expressed globally by use of a chicken actin promoter, the effects were almost entirely stomach specific. Despite severe injury, a subset of mice showed near complete healing of the gastric mucosa 11-12 wk after Cre induction, suggesting substantial gastric regenerative capacity. Finally, we show that nongenotoxic doses of tamoxifen could be used to specifically delete loxP-flanked Bmpr1a, the receptor for bone morphogenetic protein 2, 4, and 7, causing antral polyps and marked antral-pyloric hyperplasia, consistent with previous reports on Bmpr1a. Together, the results show dose-dependent, potentially reversible sensitivity of the gastric mucosa to Cre genotoxicity. Thus we propose that tamoxifen induction of Cre could be used to induce genotoxic injury to study the regenerative capacity of the gastric epithelial stem cell.

Targeted deletion of Kcne2 causes gastritis cystica profunda and gastric neoplasia

Gastric cancer is the second leading cause of cancer death worldwide. Predisposing factors include achlorhydria, Helicobacter pylori infection, oxyntic atrophy and TFF2-expressing metaplasia. In parietal cells, apical potassium channels comprising the KCNQ1 α subunit and the KCNE2 β subunit provide a K⁺ efflux current to facilitate gastric acid secretion by the apical H⁺K⁺ATPase. Accordingly, genetic deletion of murine Kcnq1 or Kcne2 impairs gastric acid secretion. Other evidence has suggested a role for KCNE2 in human gastric cancer cell proliferation, independent of its role in gastric acidification. Here, we demonstrate that 1-year-old Kcne2^−/− mice in a pathogen-free environment all exhibit a severe gastric preneoplastic phenotype comprising gastritis cystica profunda, 6-fold increased stomach mass, increased Ki67 and nuclear Cyclin D1 expression, and TFF2- and cytokeratin 7-expressing metaplasia. Some Kcne2^−/−mice also exhibited pyloric polypoid adenomas extending into the duodenum, and neoplastic invasion of thin walled vessels in the sub-mucosa. Finally, analysis of human gastric cancer tissue indicated reduced parietal cell KCNE2 expression. Together with previous findings, the results suggest KCNE2 disruption as a possible risk factor for gastric neoplasia.

Advance in relationship between TFF3 and gastric cancer

Trefoil factor family (TFF) consists of three members, including TFF1, TFF2 and TFF3. TFF has such functions as maintaining gut mucosal integrity, promoting epithelial cell restitution, as well as cell signal transduction, modulating apoptosis and enhancing invasion. Therefore, TFF plays crucial roles in the process of inflammation and tumorigenesis. Researches recently have indicated that TFF3 plays an important role in gastric cancer, especially in intestinal gastric carcinoma.

Bile acid induces expression of COX-2 through the homeodomain transcription factor CDX1 and orphan nuclear receptor SHP in human gastric cancer cells

The caudal-related homeobox gene, CDX1, encodes for an intestinal-specific transcription factor and is involved in the induction of intestinal metaplasia (IM) of the stomach in gastric cancer. Gastric IM induced by bile reflux is a precancerous gastric adenocarcinomal lesion and has been associated with the induction of cyclooxygenase-2 (COX-2). In this study, we demonstrate the molecular mechanisms underlying the transcriptional regulation of COX-2 by bile acid in gastric cells. We noted that the ectopic expression of CDX1 enhanced COX-2 gene expression and that bile acid was associated with the induction of CDX1 expression. Furthermore, the induction of CDX1 by bile acid was mediated by the orphan nuclear receptor, small heterodimer partner (SHP). Finally, it was verified that the expression of COX-2, CDX1, SHP and CCAAT element-binding protein beta messenger RNA in human IM lesions were significantly higher than in lesions associated with gastritis. Collectively, these results reveal that bile acid induces an increase in the gene expression of COX-2 via the sequential transcriptional induction of SHP and CDX1 in precancerous lesions of human gastric cancer.

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.

Accelerated progression of gastritis to dysplasia in the pyloric antrum of TFF2 -/- C57BL6 x Sv129 Helicobacter pylori-infected mice

Trefoil factor family 2 (TFF2) is up-regulated in Helicobacter spp.-infected gastric tissues of both humans and mice. To ascertain the biological effects of TFF2 in vivo, TFF2(-/-) C57BL/6 x Sv129 and wild-type (WT) C57BL/6 x Sv129 mice were orally infected with Helicobacter pylori SS1. Mice were evaluated for gastric H. pylori colonization, pathology, and cytokine profiles at 6 and 19 months post inoculation (pi). At 6 months pi, there was a significant difference (P < 0.05) for epithelial criteria (mucosal defects, atrophy, hyperplasia, pseudopyloric metaplasia, and dysplasia) in the corpus of TFF2(-/-) versus WT mice. At 19 months pi, a similar statistical difference in epithelial parameters was noted in the antrum of TFF2(-/-) versus WT mice (P < 0.01). All of the TFF2(-/-) H. pylori-infected mice had high-grade antral dysplasia, including gastric intraepithelial neoplasia, which was statistically significant (P < 0.05) compared with the infected WT mice. Levels of interferon-gamma were markedly elevated in the gastric mucosa of infected TFF2(-/-) mice at both 6 and 19 months pi. TFF2 provided a cytoprotective and/or anti-inflammatory effect against the progression of premalignant lesions of the gastric corpus at 6 months pi and in the pyloric antrum in H. pylori-infected mice at 19 months pi. These data support a protective role for TFF2 in part by modulating levels of gastric interferon-gamma in the development of H. pylori-associated premalignancy of the distal stomach.