Expression of Pdx-1 in human gastric metaplasia and gastric adenocarcinoma

[Characteristics of gastric neuroendocrine tumors and the PDX-1 transcription factor expression]

OBJECTIVE

To study the features of gastric neuroendocrine tumors (NETs) and the diagnostic and prognostic significance of PDX-1 expression in them.

MATERIAL AND METHODS

207 NETs identified in 56 men and 115 women (59 had multiple NETs), and 94 cases of gastric cancer (comparison group) were studied morphologically and immunohistochemically.

RESULTS

In more than half of the cases (54.93%), NETs were localized in the body of the stomach; the cardiac and antral parts of the stomach accounted for 8.64% and 11.73%, respectively. NETs of the cardiac region predominated in men, and of the body and antrum - in women. NETs of the cardiac region predominated in men, and of the body and antrum - in women. The vast majority of NETs were highly differentiated (89.20%), of which Grade 1, 2 and 3 were 55.41%, 40.76% and 3.82%, respectively. Neuroendocrine carcinomas (NEC) accounted for 10.80% of all NET cases. NECs were more often localized in the cardiac part of the stomach and accounted for 35.71% of all NETs in the cardiac part. The share of NEC among all NETs of the antrum was 15.79%, of the body of the stomach - only 3.37%. Metastases were found in 17.90% of NETs. Expression of PDX-1 was detected in 44.73% of NETs, 70% of NECs and 74.50% of gastric cancers.

CONCLUSION

PDX-1 is involved in the mechanisms of precancerous and cancerous lesions of the stomach and its overexpression is detected in the majority of the most malignant NETs and gastric cancers.

Group 2 Innate Lymphoid Cells Coordinate Damage Response in the Stomach

BACKGROUND & AIMS

Severe injury to the lining of the stomach leads to changes in the epithelium (reprogramming) that protect and promote repair of the tissue, including development of spasmolytic polypeptide-expressing metaplasia (SPEM) and tuft and foveolar cell hyperplasia. Acute gastric damage elicits a type-2 inflammatory response that includes production of type-2 cytokines and infiltration by eosinophils and alternatively activated macrophages. Stomachs of mice that lack interleukin 33 (IL33) or interleukin 13 (IL13) did not undergo epithelial reprogramming after drug-induced injury. We investigated the role of group 2 innate lymphoid cells (ILC2s) in gastric epithelial repair.

METHODS

Acute gastric injury was induced in C57BL/6J mice (wild-type and RAG1 knockout) by administration of L635. We isolated ILC2s by flow cytometry from stomachs of mice that were and were not given L635 and performed single-cell RNA sequencing. ILC2s were depleted from wild-type and RAG1-knockout mice by administration of anti-CD90.2. We assessed gastric cell lineages, markers of metaplasia, inflammation, and proliferation. Gastric tissue microarrays from patients with gastric adenocarcinoma were analyzed by immunostaining.

RESULTS

There was a significant increase in the number of GATA3-positive ILC2s in stomach tissues from wild-type mice after L635-induced damage, but not in stomach tissues from IL33-knockout mice. We characterized a marker signature of gastric mucosal ILC2s and identified a transcription profile of metaplasia-associated ILC2s, which included changes in expression of Il5, Il13, Csf2, Pd1, and Ramp3; these changes were validated by quantitative polymerase chain reaction and immunocytochemistry. Depletion of ILC2s from mice blocked development of metaplasia after L635-induced injury in wild-type and RAG1-knockout mice and prevented foveolar and tuft cell hyperplasia and infiltration or activation of macrophages after injury. Numbers of ILC2s were increased in stomach tissues from patients with SPEM compared with patients with normal corpus mucosa.

CONCLUSIONS

In analyses of stomach tissues from mice with gastric tissue damage and patients with SPEM, we found evidence of type 2 inflammation and increased numbers of ILC2s. Our results suggest that ILC2s coordinate the metaplastic response to severe gastric injury.

Single-Cell Transcriptional Analyses Identify Lineage-Specific Epithelial Responses to Inflammation and Metaplastic Development in the Gastric Corpus

BACKGROUND & AIMS

Chronic atrophic gastritis can lead to gastric metaplasia and increase risk of gastric adenocarcinoma. Metaplasia is a precancerous lesion associated with an increased risk for carcinogenesis, but the mechanism(s) by which inflammation induces metaplasia are poorly understood. We investigated transcriptional programs in mucous neck cells and chief cells as they progress to metaplasia mice with chronic gastritis.

METHODS

We analyzed previously generated single-cell RNA-sequencing (scRNA-seq) data of gastric corpus epithelium to define transcriptomes of individual epithelial cells from healthy BALB/c mice (controls) and TxA23 mice, which have chronically inflamed stomachs with metaplasia. Chronic gastritis was induced in B6 mice by Helicobacter pylori infection. Gastric tissues from mice and human patients were analyzed by immunofluorescence to verify findings at the protein level. Pseudotime trajectory analysis of scRNA-seq data was used to predict differentiation of normal gastric epithelium to metaplastic epithelium in chronically inflamed stomachs.

RESULTS

Analyses of gastric epithelial transcriptomes revealed that gastrokine 3 (Gkn3) mRNA is a specific marker of mouse gastric corpus metaplasia (spasmolytic polypeptide expressing metaplasia, SPEM). Gkn3 mRNA was undetectable in healthy gastric corpus; its expression in chronically inflamed stomachs (from TxA23 mice and mice with Helicobacter pylori infection) identified more metaplastic cells throughout the corpus than previously recognized. Staining of healthy and diseased human gastric tissue samples paralleled these results. Although mucous neck cells and chief cells from healthy stomachs each had distinct transcriptomes, in chronically inflamed stomachs, these cells had distinct transcription patterns that converged upon a pre-metaplastic pattern, which lacked the metaplasia-associated transcripts. Finally, pseudotime trajectory analysis confirmed the convergence of mucous neck cells and chief cells into a pre-metaplastic phenotype that ultimately progressed to metaplasia.

CONCLUSIONS

In analyses of tissues from chronically inflamed stomachs of mice and humans, we expanded the definition of gastric metaplasia to include Gkn3 mRNA and GKN3-positive cells in the corpus, allowing a more accurate assessment of SPEM. Under conditions of chronic inflammation, chief cells and mucous neck cells are plastic and converge into a pre-metaplastic cell type that progresses to metaplasia.

Interleukin 27 Protects From Gastric Atrophy and Metaplasia During Chronic Autoimmune Gastritis

BACKGROUND & AIMS

The association between chronic inflammation and gastric carcinogenesis is well established, but it is not clear how immune cells and cytokines regulate this process. We investigated the role of interleukin 27 (IL27) in the development of gastric atrophy, hyperplasia, and metaplasia (preneoplastic lesions associated with inflammation-induced gastric cancer) in mice with autoimmune gastritis.

METHODS

We performed studies with TxA23 mice (control mice), which express a T-cell receptor against the H+/K+ adenosine triphosphatase α chain and develop autoimmune gastritis, and TxA23xEbi3-/- mice, which develop gastritis but do not express IL27. In some experiments, mice were given high-dose tamoxifen to induce parietal cell atrophy and spasmolytic polypeptide-expressing metaplasia (SPEM). Recombinant IL27 was administered to mice with mini osmotic pumps. Stomachs were collected and analyzed by histopathology and immunofluorescence; we used flow cytometry to measure IL27 and identify immune cells that secrete IL27 in the gastric mucosa. Single-cell RNA sequencing was performed on immune cells that infiltrated stomach tissues.

RESULTS

We identified IL27-secreting macrophages and dendritic cell in the corpus of mice with chronic gastritis (TxA23 mice). Mice deficient in IL27 developed more severe gastritis, atrophy, and SPEM than control mice. Administration of recombinant IL27 significantly reduced the severity of inflammation, atrophy, and SPEM in mice with gastritis. Single-cell RNA sequencing showed that IL27 acted almost exclusively on stomach-infiltrating CD4+ T cells to suppress expression of inflammatory genes.

CONCLUSIONS

In studies of mice with autoimmune gastritis, we found that IL27 is an inhibitor of gastritis and SPEM, suppressing CD4+ T-cell-mediated inflammation in the gastric mucosa.

Mucins, trefoil factors and pancreatic duodenal homeobox 1 expression in spasmolytic polypeptide expressing metaplasia and intestinal metaplasia adjacent to gastric carcinomas

INTRODUCTION

Gastric cancers are the second cause of cancer related deaths all around the world but gastric carcinogenesis remains a mystery. Intestinal metaplasia (IM) and spasmolytic polypeptide expressing metaplasia (SPEM) are the two types of preneoplastic metaplasias. In this study, we aimed to investigate expression of Pancreatic duodenal homeobox 1 (PDX1), mucins (MUCs), trefoil factors (TFFs) in SPEM and IM surrounding gastric carcinomas.

MATERIAL AND METHODS

Tissue samples of tumor adjacent gastric mucosa including IM (n = 61) and SPEM (n = 36) from 70 gastrectomy specimens were used for immunohistochemical analysis of PDX1, mucins (MUC5AC, MUC6) and trefoil factors (TFF2, TFF3).

RESULTS

Nuclear expression of PDX1 was present in both SPEM (32/36) and IM (60/61) and there was no significant difference in expression of PDX1 between the two types of metaplasias. While TFF3 and MUC5AC were abundant in IM, SPEM showed 100% expression of TFF2 and MUC6 and also lower positivity with TFF3 and MUC5AC. PDX1 positivity was related to expression of MUC5AC (60/61, p < 0.001) and TFF3 (60/61, p < 0.001) in IM and also associated with expression of MUC5AC (14/32, p < 0.05), MUC6 (32/32, p < 0.001), TFF2 (32/32, p < 0.001) and TFF3 (9/32, p < 0.05) in SPEM. Coexpression of TFF3 and TFF2 was present in 10 of 36 (27.7%) samples of SPEM and also 29 of 61 (47.5%) samples of IM exhibited dual expression of trefoil peptides.

CONCLUSIONS

PDX1 may affect the development of SPEM and IM. Expression patterns of TFFs and MUCs may indicate that IM evolves from SPEM.

[Differential diagnostic value of the expression of the transcription factor PDX-1 in neuroendocrine and non-neuroendocrine tumors of the pancreas and other organs]

An important role in the differentiation of tissues in different organs is played by transforming factors (TFs); pancreatic and duodenal homebox 1 (PDX-1) is one of the earliest factors for pancreatic cells. Many malignant tumors, including neuroendocrine tumors (NETs), are similar in structure, and therefore the actual problem of oncomorphology is to search for narrow-specific markers and TFs.

AIM

to comparatively analyze and assess the value of the expression of the TF PDX-1 in NETs and non-NETs of different localization and histogenetic origin.

MATERIAL AND METHODS

Anti-PDX-1 antibodies were used to study 528 tumors divided into 3 groups: Group 1 included 394 NETs, among them there were those of the pancreas (n=173), stomach (n=46), bowel (n=65), lung (n=40), thymus (n=8), kidney (n=6), Merkel's cell carcinomas (n=14), NETs of the breast (n=3), larynx (n=2), trachea (n=2), bladder (n=1), and metastatic NETs (n=34) of unknown primary site; Group 2 consisted of 16 tumors, of them there were paragangliomas (n=6), medullary thyroid cancers (MTC) (n=6) and adrenal pheochromocytomas (APCC) (n=4); Group 3 comprised 118 non-NETs, among them there were tumors of the pancreas (n=54), stomach (n=26), bowel (n=17), lung (n=11), breast (n=3), kidney (n=4), adrenal glands (n=2), and bladder (n=1).

RESULTS

PDX-1 was positive in 75.1% (130/173) of pancreatic NETs, all insulinomas (50/50), gastrinomas (11/11), somatostatinomas (3/3), ACTH-producing tumors (2/2); PDX-1 was positive in the non-functioning pancreatic NETs, all PPomas (19/19), 76.1% (35/46) of NETs without the hormone detected, 50% (2/4) of calcitoninomas, and 21.1% (8/38) of silent glucagonomas. PDX-1 was positive in 32.4% (11/34) of carcinoids and 50% (6/12) of neuroendocrine carcinomas, all duodenal NETs (18/18), 90% (9/10) of rectal carcinoids and 30.8% (4/13) colonic carcinoids, 37.5% (3/8) of thymic/mediastinal carcinoids, 66.7% (4/6) of kidney carcinoids, and 37.5% (9/24) of metastatic NETs of unknown primary site. PDX-1 was negative in all carcinoids of the colon and sigmoid (0/5), ileum and jejunum (0/24), lung (0/40), trachea (0/2), larynx (0/2), Merkel's cell carcinoma (0/14), breast (0/3), bladder (0/1), as well as MTC (0/6), APCC (0/4), and paragangliomas (0/6). PDX-1-positive non-NETs included 81.8% (18/22) of adenocarcinomas (AC) and all serous cystic, mucinous cystic, intraductal and acinar cell tumors of the pancreas (4/4, 3/3, 2/2, and 3/3), 57.1% of AC (8/14) and 83.3% of signet ring cell carcinomas of the stomach (10/12), 56.2% AC of the bowel (9/17), bladder cancer (1/1). PDX-1 was negative in all anaplastic cancers (0/2) and solid pseudopapillary tumors of the pancreas (0/20), cancers of the lung (0/11), kidney (0/4), breast (0/3), and adrenal glands (0/2).

CONCLUSION

The expression of PDX-1 is very specific for most digestive tract NETs and non-NETs. Pancreatic ductal and acinar cell tumors and gastric signet ring cell carcinomas are most commonly PDX-1-positive. Most tumors that do not originate from the digestive tract have a PDX-1 negative immunophenotype.

Host factors influence Barrett's carcinogenesis: findings from a mouse gastroduodenal reflux model

BACKGROUND

Rat gastroduodenal reflux models have been used for analyzing Barrett's carcinogenesis. Mice seem to be more useful than rats for studies targeting genes.

METHODS

We induced gastroduodenal contents reflux by esophagojejunostomy using C57BL/6J mice. Mice were divided into a standard diet and high-fat diet groups and kept for 60 weeks. Bile was sampled from the gallbladder to analyze bile acid fractions, and the esophagus was removed for a histological investigation. Human esophagogastric junction adenocarcinoma cells (OE19) were exposed to taurocholic acid (TCA), after which cell proliferative activity was measured. Rat esophageal cancer cell lines, ESCC-DR and ESCC-DRtca with higher malignant potential induced by continuous TCA exposure, were used to perform comprehensive genetic analysis (CGH).

RESULTS

Barrett's epithelium onset occurred in all mice, and no differences in histological changes were noted between the standard diet and high-fat diet groups. However, no development of adenocarcinoma was noted. Most of the mouse bile acid was taurine conjugates. In the experiment using OE-19 cells, TCA promotes cell proliferation in a dose-dependent manner. Array CGH analysis revealed a large number of chromosomal abnormalities in the ESCC-DR, in addition to genetic abnormalities such as in the UGT2B gene, the substrate of which is bile acid. TCA administration resulted in more chromosomal abnormalities being detected.

CONCLUSIONS

We showed the effects of TCA in cancer progression in vitro. However, Barrett's adenocarcinoma onset rates differ between mice and rats despite undergoing similar reflux stimulation including taurine-conjugated bile acids being detected in mouse bile juice. These results suggest that host factors seem to influence Barrett's carcinogenesis.

Columnar Metaplasia in Three Types of Surgical Mouse Models of Esophageal Reflux

BACKGROUND AND AIMS

Esophageal adenocarcinoma develops in the setting of gastroesophageal reflux and columnar metaplasia in distal esophagus. Columnar metaplasia arising in gastroesophageal reflux models has developed in rat; however, gastroesophageal reflux models in mice have not been well-characterized.

METHODS

One hundred thirty-five C57Bl/6J mice aged 8 weeks old were divided into the following operations: esophagogastrojejunostomy (side-to-side) (EGJ), esophageal separation and esophagojejunostomy (end-to-side) (EJ), and EJ and gastrectomy (end-to-side) (EJ/TG). The animals were euthanized after 40 weeks and the histology of the junction was examined. Immunohistochemistry for p53, PDX-1, and CDX-2 was performed.

RESULTS

Metaplasia developed in 15/33 (45.5%) of EGJ, 0/38 (0%) of EJ, and 6/39 (15.4%) of EJ/TG (P < .05) and dysplasia developed 7/33 (21.2%) of EGJ, 0% of EJ, and 1/39 (2.6%) of EJ/TG. p53 was positive in all of the dysplastic regions, 12/15 (80%) metaplasias in the EGJ model, and 1/6 (16.7%) metaplasia in the EJ/TG model. CDX-2 was positive in all cases of metaplasias, but decreased in some cases of dysplasia. PDX-1 was positive in 7/8 (88%) cases of dysplasia and in 15/21 (71%) cases of metaplasia (P < .05).

CONCLUSIONS

The EGJ model, which causes reflux of gastric acid and duodenal content, developed metaplasia and dysplasia most frequently. No metaplasia developed in the EJ model in which gastric juice and duodenal content mixed before reflux. Thus, duodenal contents alone can induce columnar metaplasia and dysplasia; however, the combination of gastric acid with duodenal content reflux can cause metaplasia and dysplasia more efficiently.

Murine Models of Gastric Corpus Preneoplasia

Intestinal-type gastric adenocarcinoma evolves in a field of pre-existing metaplasia. Over the past 20 years, a number of murine models have been developed to address aspects of the physiology and pathophysiology of metaplasia induction. Although none of these models has achieved true recapitulation of the induction of adenocarcinoma, they have led to important insights into the factors that influence the induction and progression of metaplasia. Here, we review the pathologic definitions relevant to alterations in gastric corpus lineages and classification of metaplasia by specific lineage markers. In addition, we review present murine models of the induction and progression of spasmolytic polypeptide (TFF2)-expressing metaplasia, the predominant metaplastic lineage observed in murine models. These models provide a basis for the development of a broader understanding of the physiological and pathophysiological roles of metaplasia in the stomach.

Characterization of progressive metaplasia in the gastric corpus mucosa of Mongolian gerbils infected with Helicobacter pylori

Spasmolytic polypeptide-expressing metaplasia (SPEM) and intestinal metaplasia are considered neoplastic precursors of gastric adenocarcinoma in humans. Loss of parietal cells causes the development of SPEM in the gastric corpus and then chronic inflammation drives SPEM toward a more proliferative lineage. Mongolian gerbils infected with Helicobacter pylori develop chronic gastritis and metaplasia, mimicking aspects of human gastritis with H. pylori infection. We therefore examined metaplastic lineages in the gastric corpus mucosa of gerbils infected by H. pylori strain 7.13, which produces rapid onset of severe inflammation. Six weeks following H. pylori infection, Griffonia simplicifolia lectin II (GSII)-positive SPEM developed in the base of oxyntic glands in association with parietal cell loss and inflammation. In association with severe inflammation, SPEM glands evolved into aberrant phenotypes, including branched lesions, dilated lesions, and penetrating invasive glands. Mucin 4 (MUC4) was up-regulated in SPEM and progressive SPEM. Clusterin was expressed in the tips of branched and dilated lesions and throughout regions of invasive glands. Intriguingly, clusterin-positive regions in these lesions expressed Ki67 and matrix metalloproteinase 7 (MMP-7). These same regions were also positive for expression of phospho-IkBα, suggestive of activated NFkB signalling. These findings suggest that clusterin-positive regions in progressive phenotypes of SPEM have invasive characteristics. Thus, H. pylori infection in gerbils induces SPEM, which then can progress to further aberrant and invasive metaplastic phenotypes. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Expression of Activated Ras in Gastric Chief Cells of Mice Leads to the Full Spectrum of Metaplastic Lineage Transitions

BACKGROUND & AIMS

Gastric cancer develops in the context of parietal cell loss, spasmolytic polypeptide-expressing metaplasia (SPEM), and intestinal metaplasia (IM). We investigated whether expression of the activated form of Ras in gastric chief cells of mice leads to the development of SPEM, as well as progression of metaplasia.

METHODS

We studied Mist1-CreERT2Tg/+;LSL-K-Ras(G12D)Tg/+ (Mist1-Kras) mice, which express the active form of Kras in chief cells on tamoxifen exposure. We studied Mist1-CreERT2Tg/+;LSL-KRas (G12D)Tg/+;R26RmTmG/+ (Mist1-Kras-mTmG) mice to examine whether chief cells that express active Kras give rise to SPEM and IM. Some mice received intraperitoneal injections of the Mitogen-activated protein kinase kinase (MEK) inhibitor, selumetinib, for 14 consecutive days. Gastric tissues were collected and analyzed by immunohistochemistry, immunofluorescence, and quantitative polymerase chain reaction.

RESULTS

Mist1-Kras mice developed metaplastic glands, which completely replaced normal fundic lineages and progressed to IM within 3-4 months after tamoxifen injection. The metaplastic glands expressed markers of SPEM and IM, and were infiltrated by macrophages. Lineage tracing studies confirmed that the metaplasia developed directly from Kras (G12D)-induced chief cells. Selumetinib induced persistent regression of SPEM and IM, and re-established normal mucosal cells, which were derived from normal gastric progenitor cells.

CONCLUSIONS

Expression of activated Ras in chief cells of Mist1-Kras mice led to the full range of metaplastic lineage transitions, including SPEM and IM. Inhibition of Ras signaling by inhibition of MEK might reverse preneoplastic metaplasia in the stomach.

Identification of alanyl aminopeptidase (CD13) as a surface marker for isolation of mature gastric zymogenic chief cells

Injury and inflammation in the gastric epithelium can cause disruption of the pathways that guide the differentiation of cell lineages, which in turn can cause persistent alterations in differentiation patterns, known as metaplasia. Metaplasia that occurs in the stomach is associated with increased risk for cancer. Methods for isolating distinct gastric epithelial cell populations would facilitate dissection of the molecular and cellular pathways that guide normal and metaplastic differentiation. Here, we identify alanyl aminopeptidase (CD13) as a specific surface marker of zymogenic chief cells (ZCs) in the gastric epithelium. We show that 1) among gastric epithelial cells alanyl aminopeptidase expression is confined to mature ZCs, and 2) its expression is lost en route to metaplasia in both mouse and human stomachs. With this new marker coupled with new techniques that we introduce for dissociating gastric epithelial cells and overcoming their constitutive autofluorescence, we are able to reliably isolate enriched populations of ZCs for both molecular analysis and for the establishment of ZC-derived ex vivo gastroid cultures.

Establishment of novel in vitro mouse chief cell and SPEM cultures identifies MAL2 as a marker of metaplasia in the stomach

Oxyntic atrophy in the stomach leads to chief cell transdifferentiation into spasmolytic polypeptide expressing metaplasia (SPEM). Investigations of preneoplastic metaplasias in the stomach are limited by the sole reliance on in vivo mouse models, owing to the lack of in vitro models for distinct normal mucosal lineages and metaplasias. Utilizing the Immortomouse, in vitro cell models of chief cells and SPEM were developed to study the characteristics of normal chief cells and metaplasia. Chief cells and SPEM cells isolated from Immortomice were cultured and characterized at both the permissive (33°C) and the nonpermissive temperature (39°C). Clones were selected on the basis of their transcriptional expression of specific stomach lineage markers (named ImChief and ImSPEM) and protein expression and growth were analyzed. The transcriptional expression profiles of ImChief and ImSPEM cells were compared further by using gene microarrays. ImChief cells transcriptionally express most chief cell markers and contain pepsinogen C and RAB3D-immunostaining vesicles. ImSPEM cells express the SPEM markers TFF2 and HE4 and constitutively secrete HE4. Whereas ImChief cells cease proliferation at the nonpermissive temperature, ImSPEM cells continue to proliferate at 39°C. Gene expression profiling of ImChief and ImSPEM revealed myelin and lymphocyte protein 2 (MAL2) as a novel marker of SPEM lineages. Our results indicate that the expression and proliferation profiles of the novel ImChief and ImSPEM cell lines resemble in vivo chief and SPEM cell lineages. These cell culture lines provide the first in vitro systems for studying the molecular mechanisms of the metaplastic transition in the stomach.

Down-regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5: a novel mechanism for inhibition of cellular proliferation and insulin secretion by somatostatin

Somatostatin (SST) is a regulatory peptide and acts as an endogenous inhibitory regulator of the secretory and proliferative responses of target cells. SST’s actions are mediated by a family of seven transmembrane domain G protein-coupled receptors that comprise five distinct subtypes (SSTR1-5). SSTR5 is one of the major SSTRs in the islets of Langerhans. Homeodomain-containing transcription factor pancreatic and duodenal homeobox-1 (PDX-1) is essential for pancreatic development, β cell differentiation, maintenance of normal β cell functions in adults and tumorigenesis. Recent studies show that SSTR5 acts as a negative regulator for PDX-1 expression and that SSTR5 mediates somatostatin’s inhibitory effect on cell proliferation and insulin expression/excretion through down-regulating PDX-1 expression. SSTR5 exerts its inhibitory effect on PDX-1 expression at both the transcriptional level by down-regulating PDX-1 mRNA and the post-translational level by enhancing PDX-1 ubiquitination. Identification of PDX-1 as a transcriptional target for SSTR5 may help in guiding the choice of therapeutic cancer treatments.

Notch1 activation up-regulates pancreatic and duodenal homeobox-1

Transcription factor pancreatic and duodenal homeobox-1 (PDX-1) plays an essential role in pancreatic development, β-cell differentiation, maintenance of normal β-cell function and tumorigenesis. PDX-1 expression is tightly controlled through a variety of mechanisms under different cellular contexts. We report here that overexpression of Notch1 intracellular domain (NICD), an activated form of Notch1, enhanced PDX-1 expression in both PDX-1 stable HEK293 cells and mouse insulinoma β-TC-6 cells, while NICD shRNA inhibited the enhancing effect. NICD-enhanced PDX-1 expression was accompanied by increased insulin expression/secretion and cell proliferation in β-TC-6 cells, which was reversed by NICD shRNA. Cre activation-induced specific expression of NICD in islet β cells of transgenic β^NICD+/+ mice induced increased expression of PDX-1, insulin and proliferating cell nuclear antigen (PCNA) and decreased expression of p27 with accompanied fasting hyperinsulinemia and hypoglycemia and altered responses to intraperitoneal glucose tolerance test. Systemically delivered NICD shRNA suppressed islet expression of PDX-1 and reversed the hypoglycemia and hyperinsulinemia. Moreover, expression levels of NICD were correlated with those of PDX-1 in human pancreatic neuroendocrine tumor. Thus, Notch1 acts as a positive regulator for PDX-1 expression, cooperates with PDX-1 in the development of insulin overexpression and islet cell neoplasia and represents a potential therapeutic target for islet neoplasia.

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

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

The ubiquitin ligase Mindbomb 1 coordinates gastrointestinal secretory cell maturation

After cell fate specification, differentiating cells must amplify the specific subcellular features required for their specialized function. How cells regulate such subcellular scaling is a fundamental unanswered question. Here, we show that the E3 ubiquitin ligase Mindbomb 1 (MIB1) is required for the apical secretory apparatus established by gastric zymogenic cells as they differentiate from their progenitors. When Mib1 was deleted, death-associated protein kinase-1 (DAPK1) was rerouted to the cell base, microtubule-associated protein 1B (MAP1B) was dephosphorylated, and the apical vesicles that normally support mature secretory granules were dispersed. Consequently, secretory granules did not mature. The transcription factor MIST1 bound the first intron of Mib1 and regulated its expression. We further showed that loss of MIB1 and dismantling of the apical secretory apparatus was the earliest quantifiable aberration in zymogenic cells undergoing transition to a precancerous metaplastic state in mouse and human stomach. Our results reveal a mechanistic pathway by which cells can scale up a specific, specialized subcellular compartment to alter function during differentiation and scale it down during disease.

Proteomic profiling of paraffin-embedded samples identifies metaplasia-specific and early-stage gastric cancer biomarkers

Early diagnosis and curative resection are the predominant factors associated with increased survival in patients with gastric cancer. However, most gastric cancer cases are still diagnosed at later stages. Since most pathologic specimens are archived as FFPE samples, the ability to use them to generate expression profiles can greatly improve cancer biomarker discovery. We sought to uncover new biomarkers for stomach preneoplastic metaplasias and neoplastic lesions by generating proteome profiles using FFPE samples. We combined peptide isoelectric focusing and liquid chromatography-tandem mass spectrometry analysis to generate proteomic profiles from FFPE samples of intestinal-type gastric cancer, metaplasia, and normal mucosa. The expression patterns of selected proteins were analyzed by immunostaining first in single tissue sections from normal stomach, metaplasia, and gastric cancer and later in larger tissue array cohorts. We detected 60 proteins up-regulated and 87 proteins down-regulated during the progression from normal mucosa to metaplasia to gastric cancer. Two of the up-regulated proteins, LTF and DMBT1, were validated as specific markers for spasmolytic polypeptide-expressing metaplasia and intestinal metaplasia, respectively. In cancers, significantly lower levels of DMBT1 or LTF correlated with more advanced disease and worse prognosis. Thus, proteomic profiling using FFPE samples has led to the identification of two novel markers for stomach metaplasias and gastric cancer prognosis.

Downregulation of pancreatic-duodenal homeobox 1 expression in breast cancer patients: a mechanism of proliferation and apoptosis in cancer

Pancreatic-duodenal homeobox 1 (PDX-1) is a transcription factor that regulates embryological pancreas development and insulin expression in adult islets. The current study investigated the expression profile and potential role of PDX-1 in breast cancer. Immunohistochemistry was performed to determine the expression pattern of PDX-1 in breast cancer and adjacent benign breast tissues. In addition, cell proliferation and the cell cycle were evaluated following the transient inhibition of PDX-1 with antisense oligonucleotides in MCF-7 human breast cancer cells. Real-time PCR and western blotting were conducted to investigate the correlation between PDX-1, P53, Ki-67, Caspase 3 and Caspase 8. These experiments demonstrated that PDX-1 was downregulated in human breast cancer tissue compared with adjacent normal breast tissue. Knockdown of PDX-1 expression in vitro in MCF-7 breast cancer cells promoted cell proliferation and disrupted the cell cycle, as demonstrated by the overexpression of P53 and Ki-67 at the mRNA and protein levels. In conclusion, the current study shows that PDX-1 regulates cell proliferation and the cell cycle in human breast cancer cells by altering the expression of the cell cycle-related genes, P53 and Ki-67. These data suggest that PDX-1 is a putative tumor suppressor in breast cancer.

Negative regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5

Somatostatin receptor subtype 5 (SSTR5) mediates the inhibitory effect of somatostatin and its analogs on insulin expression/secretion and islet cell proliferation. We provide biochemical and genetic evidence that SSTR5 exerted its physiological actions via down-regulating pancreatic and duodenal homeobox-1 (PDX-1), a β-cell-specific homeodomain-containing transcription factor. Cotransfection of SSTR5 with PDX-1 resulted in dose-dependent inhibition of PDX-1 expression in human embryonic kidney 293 cells. SSTR5 agonist RPL-1980 inhibited PDX-1 expression and abolished glucagon-like peptide 1-stimulated PDX-1 expression in mouse insulinoma β-TC-6 cells. SSTR5 knockdown by short hairpin RNA led to increased PDX-1 expression that was accompanied by enhanced insulin secretion stimulated by high glucose in β-TC6 cells and alternated expressions of cell cycle proteins that favor cell proliferation in mouse insulinoma MIN6 cells. Quantitative RT-PCR analysis showed that cotransfected SSTR5 inhibited PDX-1 mRNA expression, whereas knockdown of SSTR5 increased PDX-1 mRNA expression. In addition, we found that cotransfected wild-type SSTR5 increased PDX-1 ubiquitination in human embryonic kidney 293 cells, whereas SSTR5 P335L, a hypofunctional single nucleotide polymorphism of SSTR5, inhibited PDX-1 ubiquitination. SSTR5 knockout resulted in increased expression of PDX-1, insulin, and proliferating cell nuclear antigen in the islets of sstr(-/-) mice. Immunohistochemistry analysis showed that SSTR5 P335L was associated with elevated expression of PDX-1 in human pancreatic neuroendocrine tumor. Taken together, our studies demonstrated that SSTR5 is a negative regulator for PDX-1 expression and that SSTR5 may mediate the inhibitory effects of somatostatin and its analogs on insulin expression/secretion and cell proliferation via down-regulating PDX-1 at both transcriptional and posttranslational levels.

Pdx1 expression in pancreatic precursor lesions and neoplasms

Pancreatic and duodenal homeobox (Pdx1) is a homeobox transcription factor required for the embryonic development of the pancreas. Pdx1 expression has been earlier identified in pancreatic ductal adenocarcinomas and endocrine neoplasms. This study characterizes Pdx1 protein expression in pancreatic precursor lesions and neoplasms, including pancreatic intraepithelial neoplasia (PanIN, n=32), intraductal papillary mucinous neoplasm (IPMN, n=88), mucinous cystic neoplasm (MCN, n=3), acinar cell carcinoma (ACC, n=8), pancreatic endocrine neoplasm (PEN, n=44), pancreatoblastoma (PB, n=1), solid pseudopapillary neoplasm (n=8), invasive ductal adenocarcinoma (n=67), and nondysplastic ductal epithelium. A mouse monoclonal antibody for Pdx1 was used to examine archived surgical pathology cases and tissue microarrays containing >655 tissue cores from more than 250 pancreatic specimens. Immunohistochemical labeling for Pdx1 was performed using standard methods and scored for percentage and intensity of nuclear labeling. Among non-neoplastic pancreatic tissues, Pdx1 nuclear protein was expressed in islet cells, cells of the centroacinar cell compartment, and non-neoplastic ductal epithelium. No expression of Pdx1 was seen in non-neoplastic acinar cells. Among pancreatic neoplasms, Pdx1 consistently labeled >50% of the tumor cells in 87.5% of ACC cases and 38.6% of PEN cases. Pdx1 expression was variable in invasive ductal adenocarcinoma and precursor lesions of ductal adenocarcinomas (PanIN, IPMN, and MCN). A single case of PB was examined and it showed Pdx1 in the acinar component, but no expression in squamoid nests. Solid pseudopapillary neoplasms did not express Pdx1. This study shows Pdx1 expression in precursor lesions of ductal adenocarcinomas, PEN, ACC, and a case of PB. In the immunohistochemical evaluation of neoplasms of the pancreas, Pdx1 expression is not a finding specific to PENs and ductal adenocarcinomas, but also occurs in precursor lesions (PanIN, IPMN, MCN) and other neoplasms of the pancreas.

The relationship among PDX1, CDX2, and mucin profiles in gastric carcinomas; correlations with clinicopathologic parameters

PURPOSE

Several studies performed on pancreatic-duodenal homeobox 1 (PDX1) have demonstrated a loss of expression and negative tumor modulator effect in gastric carcinoma. Relations between PDX1 and gastric metaplasia, differentiated type of gastric carcinoma, and the early stage of the disease have been exhibited in previous reports. The aim of this study was to examine expressions of PDX1, caudal type homeobox 2 (CDX2) and mucin (MUC) profiles to address the role of PDX1 in gastric carcinogenesis and its relationship with CDX2.

METHODS

Seventy gastrectomy specimens were analyzed immunohistochemically for PDX1, CDX2, MUC2, MUC5AC, and MUC6 expressions. The sum of cytoplasmic and nuclear PDX1 immunostaining and PDX1 positivity were assessed. All of the antibodies were examined for a correlation with tumor type, clinicopathologic parameters, and metaplasias. The relation of Ki-67 proliferation index with the expression profiles was also investigated.

RESULTS

Neither PDX1 (66/70) nor CDX2 (37/70) and the mucin profiles (MUC2:11/70, MUC5AC:48/70, MUC6:41/70) showed a significant difference between differentiated and undifferentiated types of gastric carcinoma and clinicopathologic parameters. The PDX1 expression frequency was 94.3%, with an average PDX1 score of 8.8 ± 4.2. PDX1 and CDX2 expression showed a significant difference (P = 0.026 and P = 0.002, respectively) among the phenotypic classification of gastric carcinomas. All of the gastric and intestinal mixed-phenotype gastric carcinomas (GI-type) showed both PDX1 and CDX2 immunopositivity. Except for the relation of PDX1 score with MUC6 expression, no significant difference was detected between PDX1 and CDX2, MUC2, and MUC5AC expressions. A relationship between CDX2 and MUC2 and also between MUC5AC and MUC6 was found statistically. The Ki-67 proliferation index revealed a significant positive correlation with PDX1, CDX2, and MUC2 positivity.

CONCLUSIONS

PDX1 expression revealed a higher positivity in gastric carcinomas than the previous studies and showed no relation with tumor type, clinicopathologic parameters, CDX2 expression, or mucin profiles. However, a significant relation of PDX1 and CDX2 expressions among phenotypic classification of gastric carcinomas reveals an idea about similar functions for PDX1 and CDX2 in the evolution of gastric carcinoma.

The hypofunctional effect of P335L single nucleotide polymorphism on SSTR5 function

BACKGROUND

Somatostatin receptor subtype 5 (SSTR5) mediates the inhibitory effect of somatostatin on insulin expression/secretion and cell proliferation. A number of single nucleotide polymorphisms (SNPs) of SSTR5 have been identified, including P335L, a nonsynonymous SNP located in the protein C-terminal region and encrypted by the codon CCG (proline) or the codon CTG (leucine). In the present study we sought to determine the distribution of the SSTR5 P335L SNP in a cohort of pancreatic cancer patients and whether the P335L SNP affected cellular function of SSTR5 in human pancreatic cancer.

METHODS

The P335L germline genotype of 246 patients with pancreatic cancer (213 Caucasians, 16 Hispanics, and 17 African Americans) and 17 human pancreatic cell lines was determined with the TaqMan SNP Genotyping assay. Human SSTR5 leucine variant (L335) was generated by performing site-directed mutagenesis using SSTR5 proline variant (P335) as a template. Transient transfections were performed in HEK293, Mia PaCa-2, and β-TC-6 cells using Lipofectamine 2000. The expression of SSTR5 L335 was determined with a mouse monoclonal anti-SSTR5 L335 antibody generated in our laboratory. The cell proliferation rate was measured by performing MTS assays. Insulin concentration was measured by performing ELISA assays.

RESULTS

Genotyping of the patients' blood indicated that the frequency of the T allele (CT and TT genotypes) in codon 335 of SSTR5 in Caucasians, Hispanics, and African Americans was 52, 69, and 35%, respectively, which was race-dependent. Statistical analysis indicated that association between the frequency of the T allele and the existence of pancreatic cancer in each race missed significance perhaps due to limited sample size. In 17 tested human pancreatic cancer cell lines, 5 (Capan-2, HPAF-II, Panc03.27, Panc-1, and -3) were homozygous (TT genotype) and 9, including Mia PaCa-2, were heterozygous (CT genotype). Overexpression of SSTR5 L335 in Mia PaCa-2 cells enhanced cell proliferation compared to overexpression of SSTR5 P335. Overexpression of SSTR5 P335 enhanced the inhibitory effect of SSTR5 agonist RPL-1980 on cell proliferation of Mia PaCa-2 cells and glucose-stimulated insulin secretion from mouse insulinoma cells, while overexpression of SSTR5 L335 blocked the inhibitory effect of RPL-1980. Overexpression of SSTR5 L335 enhanced PDX-1 expression in Mia PaCa-2 cells. A specific monoclonal antibody was generated to detect SSTR5 P335L.

CONCLUSION

SSTR5 P335L SNP widely exists in the human population, in patients with pancreatic cancer, and is race-dependent. The SNP is also present in selected human pancreatic cancer cell lines. In contrast to SSTR5 P335, overexpression of the SSTR5 L335 variant resulted in cellular proliferation and PDX-1 overexpression in human pancreatic cancer cells. Its overexpression blocked the inhibitory effect of an SSTR5-specific analog on human pancreatic cancer cell proliferation and on glucose-stimulated insulin secretion from mouse insulinoma cells. These data suggest that SSTR5 P335L is a hypofunctional protein with a potentially harmful effect on function, as well as potential latent effect, and therefore it could affect the clinical response to somatostatin analog therapy for patients with pancreatic cancer.

Defining the cancer master switch

BACKGROUND

Recent research has focused on signaling cascades and their interactions yielding considerable insight into which genetic pathways are targeted and how they tend to be altered in tumors. Therapeutic interventions now can be designed based on the knowledge of pathways vital to tumor growth and survival. These critical targets for intervention, master switches for cancer, are termed so because the tumor attempts to "flip the switch" in a way that promotes its survival, whereas molecular therapy aims to "switch off" signals important for tumor-related processes.

METHODS

Literature review.

CONCLUSIONS

Defining useful targets for therapy depends on identifying pathways that are crucial for tumor growth, survival, and metastasis. Because not all signaling cascades are created equal, selecting master switches or targets for intervention needs to be done in a systematic fashion. This discussion proposes a set of criteria to define what it means to be a cancer master switch and provides examples to illustrate their application.

Gastric epithelial stem cells

Advances in our understanding of stem cells in the gastrointestinal tract include the identification of molecular markers of stem and early progenitor cells in the small intestine. Although gastric epithelial stem cells have been localized, little is known about their molecular biology. Recent reports describe the use of inducible Cre recombinase activity to indelibly label candidate stem cells and their progeny in the distal stomach, (ie, the antrum and pylorus). No such lineage labeling of epithelial stem cells has been reported in the gastric body (corpus). Among stem cells in the alimentary canal, those of the adult corpus are unique in that they lie close to the lumen and increase proliferation following loss of a single mature progeny lineage, the acid-secreting parietal cell. They are also unique in that they neither depend on Wnt signaling nor express the surface marker Lgr5. Because pathogenesis of gastric adenocarcinoma has been associated with abnormal patterns of gastric differentiation and with chronic tissue injury, there has been much research on the response of stomach epithelial stem cells to inflammation. Chronic inflammation, as induced by infection with Helicobacter pylori, affects differentiation and promotes metaplasias. Several studies have identified cellular and molecular mechanisms in spasmolytic polypeptide-expressing (pseudopyloric) metaplasia. Researchers have also begun to identify signaling pathways and events that take place during embryonic development that eventually establish the adult stem cells to maintain the specific features and functions of the stomach mucosa. We review the cytologic, molecular, functional, and developmental properties of gastric epithelial stem cells.

PDX-1: demonstration of oncogenic properties in pancreatic cancer

BACKGROUND

Pancreatic-duodenal homeobox 1 (PDX-1) is a transcription factor that regulates embryologic pancreas development and insulin expression in the adult islet; however, it is overexpressed in many types of cancer, including pancreatic cancer. The purpose of this study was to investigate the role of PDX-1 in tumorigenesis in human cells.

METHODS

In vitro cell proliferation, invasion, and transformation were performed in human embryonic kidney cell line (HEK 293), pancreatic cancer cell line MIA PaCa2, and human pancreatic ductal epithelial (HPDE) cells transiently or stably expressing PDX-1 or green fluorescent protein (GFP) PDX-1, with or without cotransfection of PDX-1 short hairpin RNA (shRNA). In vivo tumor formation was carried out in severe combined immunodeficiency (SCID) mice with subcutaneous injection of HEK 293 and MIA PaCa2 stably transfected cells. Cell cycle was analyzed by Western blot or immunostaining. Microarray of RNA from pancreatic adenocarcinoma cells with and without PDX-1 shRNA was performed and analyzed.

RESULTS

Transient and stable expressing PDX-1 significantly increased cell proliferation and invasion in HEK 293, human pancreatic ductal epithelial (HPDE), and MIA PaCa2 cells versus controls (P < .05), human PDX-1 shRNA reversed these effects. Expression of PDX-1 significantly increased colony formation in HEK 293, HPDE, and MIA PaCa2 cells versus controls in vitro (P < .05). PDX-1 promoted HEK 293 and MIA PaCa2 tumor formation in SCID mice as compared with that of control (P < .05). PDX-1 overexpression disrupted cell cycles proteins. PDX-1 expression was confirmed by Western blot and tracked by viewing of GFP-PDX-1 expression. Microarray data support an oncogenic role of PDX-1 in pancreas cancer cells.

CONCLUSIONS

PDX-1 induced increased cell proliferation, invasion, and colony formation in vitro, and resulted in markedly increased HEK 293 and MIA PaCa2 tumor formation in SCID mice. These data suggest that PDX-1 is a potential oncogene that regulates tumorigenesis.

The transcription factor MIST1 is a novel human gastric chief cell marker whose expression is lost in metaplasia, dysplasia, and carcinoma

The lack of reliable molecular markers for normal differentiated epithelial cells limits understanding of human gastric carcinogenesis. Recognized precursor lesions for gastric adenocarcinoma are intestinal metaplasia and spasmolytic polypeptide expressing metaplasia (SPEM), defined here by ectopic CDX2 and TFF2 expression, respectively. In mice, expression of the bHLH transcription factor MIST1, normally restricted to mature chief cells, is down-regulated as chief cells undergo experimentally induced metaplasia. Here, we show MIST1 expression is also a specific marker of human chief cells. SPEM, with and without MIST1, is present in human lesions and, akin to murine data, likely represents transitional (TFF2(+)/MIST1(+) = "hybrid"-SPEM) and established (TFF2(+)/MIST1(-) = SPEM) stages. Co-visualization of MIST1 and CDX2 shows similar progressive loss of MIST1 with a transitional, CDX2(+)/MIST1(-) hybrid-intestinal metaplasia stage. Interinstitutional analysis and comparison of findings in tissue microarrays, resection specimens, and biopsies (n > 400 samples), comprising the entire spectrum of recognized stages of gastric carcinogenesis, confirm MIST1 expression is restricted to the chief cell compartment in normal oxyntic mucosa, rare in established metaplastic lesions, and lost in intraepithelial neoplasia/dysplasia and carcinoma of various types with the exception of rare chief cell carcinoma ( approximately 1%). Our findings implicate MIST1 as a reliable marker of mature, healthy chief cells, and we provide the first evidence that metaplasia in humans arises at least in part from the chief cell lineage.

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.

Intra- and interobserver reproducibility of interpretation of immunohistochemical stains of prostate cancer

The evaluation of immunohistochemistry (IHC) is usually semiquantitative, and thus subject to observer variability. We analyzed the reproducibility of different IHC measures. Fifty TMA cores of prostate cancer were stained for PDX-1, a transcription factor overexpressed in the cytoplasm of prostate cancer cells. The strongest intensity was scored 0-3 and 1-3 was used for extent (1-33%, 34-66%, and 67-100%). The stains were evaluated twice by four observers: two genitourinary pathologists, and two medical doctors with no formal pathology training. Staining intensity was also measured with automated image analysis. The pathologists read the slides faster than nonpathologists (total time 88 and 178 min, respectively, p = 0.03). Mean weighted kappa for intraobserver agreement was 0.85 (range 0.81-0.89) for intensity and 0.43 (range 0.38-0.51) for extent with similar results among pathologists and nonpathologists. Mean weighted kappa for interobserver agreement was 0.80 (range 0.77-0.84) for intensity and 0.21 (range 0.11-0.26) for extent. The subjective estimations of intensity correlated with results of image analysis (r = 0.61-0.66, p < 0.001), but the correlation between observers was stronger (r = 0.75-0.81) and correlated better with Gleason grade. Thus, subjective assessment of intensity can be done with a high level of reproducibility while estimation of staining extent is less reliable. Although educated pathologists were faster, the level of pathology training is not crucial for obtaining reproducible results in the analysis of TMA-based studies.

Immunohistochemical staining for CDX-2, PDX-1, NESP-55, and TTF-1 can help distinguish gastrointestinal carcinoid tumors from pancreatic endocrine and pulmonary carcinoid tumors

Well-differentiated neuroendocrine tumors (WDNET) of the gastrointestinal tract, pancreas, and lung are histologically similar. Thus, predicting the site of origin of a metastasis is not possible on morphologic grounds. Prior immunohistochemical studies of WDNET have yielded conflicting results, and pancreatic and duodenal homeobox factor-1 (PDX-1) has not previously been evaluated in this context. We therefore analyzed the expression of CDX-2, PDX-1, TTF-1, and neuroendocrine secretory protein-55 (NESP-55), a recently described member of the chromogranin family, in primary and metastatic WDNET. In total, 64 gastrointestinal carcinoids (5 stomach; 5 duodenum; 31 ileum; 11 appendix; and 12 rectum); 39 pancreatic endocrine tumors (PET); and 20 pulmonary carcinoid tumors were studied. PET were positive for NESP-55 (16/39) and PDX-1 (11/39); 3/31 also showed heterogeneous positivity for CDX-2. Ileal carcinoids were exclusively positive for CDX-2 (30/31) and negative for all other markers. Appendiceal carcinoids were uniformly positive for CDX-2 (11/11). All rectal carcinoids were negative for CDX-2 and TTF-1; 2/12 were positive for PDX-1, and 1/12 for NESP-55. The gastric and duodenal carcinoids were only positive for PDX-1 (7/10). TTF-1 positivity was confined to pulmonary carcinoids (7/20); 1/20 was positive for NESP-55; and all were negative for CDX-2 and PDX-1. NESP-55 and PDX-1 positivity, in the presence of negative CDX-2 and TTF-1, was 97% specific for PET. The sensitivity and specificity of CDX-2 positivity for predicting an ileal primary, when PDX-1, NESP-55, and TTF-1 were negative, was 97% and 91%, respectively. TTF-1 positivity was confined to pulmonary carcinoids in our study but was present in only about a third of cases. A panel of these 4 markers may be useful in predicting the primary site of metastatic WDNET.

Amphiregulin-deficient mice develop spasmolytic polypeptide expressing metaplasia and intestinal metaplasia

BACKGROUND & AIMS

The loss of parietal cells from the fundic mucosa leads to the emergence of metaplastic lineages associated with an increased susceptibility to neoplastic transformation. Both intestinal metaplasia (IM) and spasmolytic polypeptide (TFF2/SP) expressing metaplasia (SPEM) have been identified in human stomach, but only SPEM is present in most mouse models of gastric metaplasia. We previously determined that loss of amphiregulin (AR) promotes SPEM induced by acute oxyntic atrophy. We have now examined whether SPEM in the AR-/- mouse predisposes the stomach to gastric neoplasia.

METHODS

Gross pathology of 18-month-old wild-type, AR-/-, and TGF-alpha-/- mice were examined. Ki-67, beta-catenin, Pdx-1, TFF3, and TFF2/SP expression was analyzed by immunohistochemistry. Metaplastic gastric mucosa was analyzed by dual immunostaining for TFF2/SP with MUC2 or TFF3.

RESULTS

By 18 months of age, more than 70% of AR-/- mice developed SPEM while 42% showed goblet cell IM labeled with MUC2, TFF3, and Pdx-1. A total of 28% had invasive gastric lesions in the fundus. No antral abnormalities were observed in AR-/- mice. Metaplastic cell lineages in AR-/- mice showed increases in cell proliferation and cytosolic beta-catenin expression. Dual staining for TFF2/SP with MUC2 or TFF3 showed glands containing both SPEM and IM with intervening cells expressing both TFF2/SP and MUC2 or TFF2/SP and TFF3.

CONCLUSIONS

AR-/- mice develop SPEM, which gives rise to goblet cell IM and invasive fundic dysplastic lesions. The AR-/- mouse represents the first mouse model for spontaneous development of fundic SPEM with progression to IM.

Intestinal metaplasia: a premalignant lesion involved in gastric carcinogenesis

Despite a plateau in incidence, gastric cancer remains a significant problem globally. The majority of gastric cancer is associated with histologically recognizable premalignant stages as first described by Pelayo Correa in the mid-1970s. The mortality from gastric cancer remains high especially in Western countries where, arguably, the index of suspicion of gastric cancer in patients presenting with upper abdominal symptoms is lower than in high prevalence countries. What is the evidence that intestinal metaplasia (IM) is a premalignant condition? What should the clinician know about IM and the relative risks of progression to gastric cancer? Finally, what are the current and future strategies that may help stratify patients into high risk and low risk for the development of gastric cancer? This review focuses on gastric IM and outlines some of the literature that discusses it as a premalignant condition. It also reviews the issue of surveillance of patients with IM in order to attempt to reduce the significant mortality of gastric cancer by detection of earlier stages of disease which are eminently treatable.

The gastric epithelial progenitor cell niche and differentiation of the zymogenic (chief) cell lineage

In the mammalian gastrointestinal tract, the cell fate decisions that specify the development of multiple, diverse lineages are governed in large part by interactions of stem and early lineage progenitor cells with their microenvironment, or niche. Here, we show that the gastric parietal cell (PC) is a key cellular component of the previously undescribed niche for the gastric epithelial neck cell, the progenitor of the digestive enzyme secreting zymogenic (chief) cell (ZC). Genetic ablation of PCs led to failed patterning of the entire zymogenic lineage: progenitors showed premature expression of differentiated cell markers, and fully differentiated ZCs failed to develop. We developed a separate mouse model in which PCs localized not only to the progenitor niche, but also ectopically to the gastric unit base, which is normally occupied by terminally differentiated ZCs. Surprisingly, these mislocalized PCs did not maintain adjacent zymogenic lineage cells in the progenitor state, demonstrating that PCs, though necessary, are not sufficient to define the progenitor niche. We induced this PC mislocalization by knocking out the cytoskeleton-regulating gene Cd2ap in Mist1(-/-) mice, which led to aberrant E-cadherin localization in ZCs, irregular ZC-ZC junctions, and disruption of the ZC monolayer by PCs. Thus, the characteristic histology of the gastric unit, with PCs in the middle and ZCs in the base, may depend on establishment of an ordered adherens junction network in ZCs as they migrate into the base.

Expression of PDX-1 in prostate cancer, prostatic intraepithelial neoplasia and benign prostatic tissue

Pancreatic duodenal homeobox 1 (PDX-1), a Hox type transcription factor, is necessary for differentiation of exocrine and endocrine pancreas, and regulates insulin gene transcription. PDX-1 expression was studied by immunohistochemistry on a tissue microarray (TMA) of 289 primary prostate cancers (PCa) from radical prostatectomy (RP) specimens with median follow-up of 48.9 months. We separately arrayed benign prostatic tissue, atrophy, high-grade prostatic intraepithelial neoplasia (HGPIN) and PCa from 40 men and also 17 lymph node metastases. Intensity and extent of immunoreactivity and their product (IRp) were evaluated by two independent observers. PDX-1 was overexpressed in cancer vs benign tissue (p<0.001), but also in atrophy and HGPIN vs cancer (p<0.001 and p=0.022, respectively). PDX-1 expression did not correlate with biochemical recurrence, but decreased with higher Gleason pattern (p<0.001) and in metastases vs primary PCa (p<0.001). Weighted kappa for interobserver agreement of intensity, extent and IRp was 0.65, 0.13 and 0.54, respectively. Presence of PDX-1 protein in benign and malignant prostatic tissue was confirmed by Western blot. In view of recent attention to the role of insulin systems in men with PCa, this protein is of interest in the pathogenesis of PCa.

PDX-1 acts as a potential molecular target for treatment of human pancreatic cancer

OBJECTIVES

The purpose of this study was to investigate whether pancreatic and duodenal homeobox factor 1 (PDX-1) could serve as a potential molecular target for the treatment of pancreatic cancer.

METHODS

Cell proliferation, invasion capacity, and protein levels of cell cycle mediators were determined in human pancreatic cancer cells transfected with mouse PDX-1 (mPDX-1) alone or with mPDX-1 short hairpin RNA (shRNA) and/or human PDX-1 shRNA (huPDX-1 shRNA). Tumor cell growth and apoptosis were also evaluated in vivo in PANC-1 tumor-bearing severe combined immunodeficient mice receiving multiple treatments of intravenous liposomal huPDX-1 shRNA.

RESULTS

mPDX-1 overexpression resulted in the significant increase of cell proliferation and invasion in MIA PaCa2, but not PANC-1 cells. This effect was blocked by knocking down mPDX-1 expression with mPDX-1 shRNA. Silencing of huPDX-1 expression in PANC-1 cells inhibited cell proliferation in vitro and suppressed tumor growth in vivo which was associated with increased tumor cell apoptosis. PDX-1 overexpression resulted in dysregulation of the cell cycle with up-regulation of cyclin D, cyclin E, and Cdk2 and down-regulation of p27.

CONCLUSIONS

PDX-1 regulates cell proliferation and invasion in human pancreatic cancer cells. Down-regulation of PDX-1 expression inhibits pancreatic cancer cell growth in vitro and in vivo, implying its use as a potential therapeutic target for the treatment of pancreatic 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.

A molecular signature of gastric metaplasia arising in response to acute parietal cell loss

BACKGROUND & AIMS

Loss of gastric parietal cells is a critical precursor to gastric metaplasia and neoplasia. However, the origin of metaplasia remains obscure. Acute parietal cell loss in gastrin-deficient mice treated with DMP-777 leads to the rapid emergence of spasmolytic polypeptide/trefoil factor family 2 (TFF2)-expressing metaplasia (SPEM) from the bases of fundic glands. We now sought to characterize more definitively the pathway for emergence of SPEM.

METHODS

Emerging SPEM lineages in gastrin-deficient mice treated with DMP-777 were examined for immunolocalization of TFF2, intrinsic factor, and Mist1, and morphologically with electron microscopy. Emerging SPEM was isolated with laser-capture microdissection and RNA was analyzed using gene microarrays. Immunohistochemistry in mouse and human samples was used to confirm up-regulated transcripts.

RESULTS

DMP-777-induced SPEM was immunoreactive for TFF2 and the differentiated chief cell markers, Mist1 and intrinsic factor, suggesting that SPEM derived from transdifferentiation of chief cells. Microarray analysis of microdissected SPEM lineages induced by DMP-777 showed up-regulation of transcripts associated with G1/S cell-cycle transition including minichromosome maintenance deficient proteins, as well as a number of secreted factors, including human epididymis 4 (HE4). HE4, which was absent in the normal stomach, was expressed in SPEM of human and mouse and in intestinal metaplasia and gastric cancer in human beings.

CONCLUSIONS

Although traditionally metaplasia was thought to originate from normal mucosal progenitor cells, these studies indicate that SPEM evolves through either transdifferentiation of chief cells or activation of a basal cryptic progenitor. In addition, induction of metaplasia elicits the expression of secreted factors, such as HE4, relevant to gastric preneoplasia.