Somatic mutations of the trefoil factor family 1 gene in gastric cancer

Decreased expression of gastrokine 1 and the trefoil factor interacting protein TFIZ1/GKN2 in gastric cancer: influence of tumor histology and relationship to prognosis

PURPOSE

Transcriptional profiling showed decreased expression of gastrokine 1 (GKN1) and the related trefoil factor interacting protein (TFIZ1/GKN2) in Helicobacter pylori infection. Decreased GKN1 and GKN2 mRNA expression has been reported in gastric adenocarcinoma. We have examined GKN1 and GKN2 protein expression in a large gastric cancer series, correlated expression with tumor subtype, and evaluated their utility as prognostic biomarkers.

EXPERIMENTAL DESIGN

GKN1, GKN2, and the trefoil factors TFF1 and TFF3 were examined in tissue microarrays from 155 distal gastric adenocarcinomas. Immunohistochemical expression was correlated with clinical outcome. GKN1 and GKN2 expression was measured by real-time PCR and Western analysis in samples of gastric cancer and adjacent nonneoplastic mucosa.

RESULTS

GKN1 was lost in 78% of diffuse and 42% of intestinal cancers (P < 0.0001, diffuse versus intestinal). GKN2 expression was lost in 85% of diffuse and 54% of intestinal type cancers (P < 0.002). GKN1 and GKN2 down-regulation were confirmed by Western and real-time PCR analysis. Loss of either protein was associated with significantly worse outcome in intestinal-type tumors by univariate analysis; and GKN2 loss remained a predictor of poor outcome in multivariate analysis (P < 0.033). TFF1 was lost in >70%, and TFF3 was expressed in approximately 50% of gastric cancers.

CONCLUSIONS

Loss of GKN1 and GKN2 expression occurs frequently in gastric adenocarcinomas, especially in the diffuse subtype. GKN1 and GKN2 loss are associated with shorter overall survival in the intestinal subtype.

STAT3 and STAT1 mediate IL-11-dependent and inflammation-associated gastric tumorigenesis in gp130 receptor mutant mice

Deregulated activation of STAT3 is frequently associated with many human hematological and epithelial malignancies, including gastric cancer. While exaggerated STAT3 signaling facilitates an antiapoptotic, proangiogenic, and proproliferative environment for neoplastic cells, the molecular mechanisms leading to STAT3 hyperactivation remain poorly understood. Using the gp130(Y757F/Y757F) mouse model of gastric cancer, which carries a mutated gp130 cytokine receptor signaling subunit that cannot bind the negative regulator of cytokine signaling SOCS3 and is characterized by hyperactivation of the signaling molecules STAT1 and STAT3, we have provided genetic evidence that IL-11 promotes chronic gastric inflammation and associated tumorigenesis. Expression of IL-11 was increased in gastric tumors in gp130(Y757F/Y757F) mice, when compared with unaffected gastric tissue in wild-type mice, while gp130(Y757F/Y757F) mice lacking the IL-11 ligand-binding receptor subunit (IL-11Ralpha) showed normal gastric STAT3 activation and IL-11 expression and failed to develop gastric tumors. Furthermore, reducing STAT3 activity in gp130(Y757F/Y757F) mice, either genetically or by therapeutic administration of STAT3 antisense oligonucleotides, normalized gastric IL-11 expression and alleviated gastric tumor burden. Surprisingly, the genetic reduction of STAT1 expression also reduced gastric tumorigenesis in gp130(Y757F/Y757F) mice and coincided with reduced gastric inflammation and IL-11 expression. Collectively, our data have identified IL-11 as a crucial cytokine promoting chronic gastric inflammation and associated tumorigenesis mediated by excessive activation of STAT3 and STAT1.

Are trefoil factors oncogenic?

Trefoil factors (TFFs), in particular TFF1, are classical estrogen-regulated genes and have served as markers of estrogen gene regulation by various environmental estrogens. TFFs are also regulated by several other factors including growth hormone (hGH), insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF) and various oncogenic stimuli. TFFs are secreted proteins present in serum and possess the potential to act as growth factors promoting cell survival, anchorage-independent growth and motility. Recent compelling evidence has emerged from experimental and clinical studies to indicate a pivotal role of TFFs in oncogenic transformation, growth and metastatic extension of common human solid tumours. This review will summarize the current evidence for the involvement of TFFs in human 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.

Phorbol ester up-regulates phospholipase D1 but not phospholipase D2 expression through a PKC/Ras/ERK/NFkappaB-dependent pathway and enhances matrix metalloproteinase-9 secretion in colon cancer cells

Despite its importance in cell proliferation and tumorigenesis, very little is known about the molecular mechanism underlying the regulation of phospholipase D (PLD) expression. PLD isozymes are significantly co-overexpressed with cancer marker genes in colorectal carcinoma. Phorbol 12-myristate 13-acetate (PMA) treatment, as a mitogenic signal in colon cancer cells, selectively increases PLD1 expression in transcription and post-transcription. Moreover, experiments using intraperitoneal injection of PMA into mice showed selective PLD1 induction in the intestine and lung tissues, which suggests its physiological relevance in vivo. Therefore, we have undertaken a detailed analysis of the effects of PMA on the promoter activity of PLD genes. Protein kinase C inhibitors, but not a protein kinase A inhibitor, were found to suppress the up-regulation of PLD1 but not PLD2. Dominant-negative mutants of Ras, Raf, and MEK suppressed the induction and activity of PLD1. Moreover, depletion of the supposedly involved proteins reduced the endogenous PLD1 protein level. An important role for NFkappaB as a downstream target of ERK in PMA-induced PLD1 induction was also demonstrated using the inhibitor, small interfering RNA, chromatin immunoprecipitation assay, and site-specific mutagenesis. Furthermore, inhibitors of these signaling proteins and depletion of PLD1 suppressed PMA-induced matrix metalloproteinase-9 secretion and PLD1 induction. In conclusion, we demonstrate for the first time that induction of PLD1 through a protein kinase C/Ras/ERK/NFkappaB-dependent pathway is involved in the secretion of matrix metalloproteinase-9 in colorectal cancer cells.

Decisions for extent of gastric surgery in gastric cancer patients: younger patients require more attention than the elderly

BACKGROUND AND OBJECTIVES

There is a prevailing belief that young patients with gastric adenocarcinomas have a more aggressive disease.

METHODS

We reviewed the prospectively collected database of 753 gastric adenocarcinomas patients who had undergone curative gastrectomy. Clinicopathological factors and the survival rates for each pathological TNM stage were compared between patients younger than 40 years of age and the others.

RESULTS

Fifty-four (9.8%) patients were younger than 40 years of age. The overall accuracy of the intra-operative stage was 62.5%; 54.0% in the young patients and 63.5% in older patients (P = 0.006). Intraoperative under-staging was more commonly seen in the younger patients when compared to the older patients. These trends were more prominent in patients with surgical stage I disease. Age proved to be an independent risk factor influencing the accuracy of intraoperative staging using a logistic regression analysis. There was no difference in overall 3-year survival rate between the two age groups for each pathological TNM stage.

CONCLUSIONS

The present study showed that intra-operative under-staging was more common in young patients with gastric cancer, especially with stage I disease. This finding raises the concern for inaccurate diagnosis and surgical under treatment in younger patients with stage I gastric cancer.

Attack and defence in the gastric epithelium - a delicate balance

The gastric epithelium is a complex structure formed into tubular branched gastric glands. The glands contain a wide variety of cell types concerned with the secretion of hydrochloric acid, proteases, mucus and a range of signalling molecules. All cell types originate from stem cells in the neck region of the gland, before migrating and differentiating to assume their characteristic positions and functions. Endocrine and local paracrine mediators are of crucial importance for maintaining structural and functional integrity of the epithelium, in the face of a hostile luminal environment. The first such mediator to be recognized, the hormone gastrin, was identified over a century ago and is now established as the major physiological stimulant of gastric acid secretion. Recent studies, including those using mice that overexpress or lack the gastrin gene, suggest a number of previously unrecognized roles for this hormone in the regulation of cellular proliferation, migration and differentiation. This review focuses on the identification of hitherto unsuspected gastrin-regulated genes and discusses the paracrine cascades that contribute to the maintenance of gastric epithelial architecture and secretory function. Helicobacter infection is also considered in cases where it shares targets and signalling mechanisms with gastrin.

Expression profiles of MUC mucins and trefoil factor family (TFF) peptides in the intrahepatic biliary system: physiological distribution and pathological significance

Mucin secreted by mucosal epithelial cells plays a role in the protection of the mucosal surface and also is involved in pathological processes. So far, MUC1-4, 5AC, 5B, 6-8, 11-13 and 15-17 genes coding the backbone mucin core protein have been identified in humans. Their diverse physiological distribution and pathological alterations have been reported. Trefoil factor family (TFF) peptides are mucin-associated molecules co-expressed with MUC mucins and involved in the maintenance of mucosal barrier and the biological behavior of epithelial and carcinoma cells. Intrahepatic biliary system is a route linking the bile canaliculi and the extrahepatic bile duct for the excretion of bile synthesized by hepatocytes. Biliary epithelial cells line in the intrahepatic biliary system, secreting mucin and other molecules involved in the maintenance and regulation of the system. In this review, the latest information regarding properties, expression profiles and regulation of MUC mucins and TFF peptides in the intrahepatic biliary system is summarized. In particular, we focus on the expression profiles and their significance of MUC mucins in developmental and normal livers, various hepatobiliary diseases and intrahepatic cholangiocarcinoma.

[Gastric adenocarcinoma: approach to a complex biological reality]

The authors review the complex biological reality of gastric adenocarcinoma from several viewpoints. It is a neoplasm histologically expressed as a dual process (intestinal and diffuse types) with a broad cytological diversity. From an epidemiological point of view, it behaves as an entity with a deep geographical asymmetry and a changing incidence, currently decreasing. There is a multifactorial etiology with a combination of genetic, infectious (H. pylori), nutritional and environmental factors. It might have a multiphasic gestation from precancerous lesions, though not always following a lineal sequence. We only know fragmentary portions of its pathogenesis whose common denominator is a potentially mutagenic mitogenic activation of the epithelial cells implicated. A good knowledge of this complex biological reality will allow the identification of better markers for an early diagnosis as well as vulnerable etiopathogenetic points for a useful prevention and therapy.

Differentiation of the Gastric Mucosa IV. Role of trefoil peptides and IL-6 cytokine family signaling in gastric homeostasis

Gastric trefoil peptides mediate mucosal repair by stimulating cell migration, inhibiting apoptosis and inflammation, and likely augmenting the barrier function of mucus. One of these, tff1, is a gastric-specific tumor suppressor gene, which when repressed is associated with gastric cancer progression. IL-6 family cytokines play an important role in maintaining gastric homeostasis by regulating tff1 and other mediators of mucosal proliferation, inflammation, angiogenesis, and apoptosis. In this review the signaling cascades downstream of the common IL-6 cytokine family coreceptor gp130 that contribute to control of this homeostasis are described, as are the pathological outcomes of imbalancing these pathways.

Trefoil factor family-1 mutations enhance gastric cancer cell invasion through distinct signaling pathways

BACKGROUND & AIMS

Trefoil factor family-1 (TFF1) is a key gastric tumor-suppressor gene. TFF1 knockout mice develop multiple gastric adenomas and carcinomas, and human gastric cancers typically lack TFF1 expression. Recently, TFF1 mutations have been found in human gastric cancer. The purpose of this study was to determine the functionality of these mutants.

METHODS

Recombinant wild-type TFF1 and the gastric cancer-associated TFF1 mutants (A10D and E13K) were produced and tested for their effect on gastric cancer cell proliferation, apoptosis, and invasion. Molecular modeling was used to guide the choice of mutants and to evaluate structure-function relationships.

RESULTS

Molecular modeling suggested that A10D and E13K altered the surface charge of the loop 1 region of TFF1 without disturbing protein stability. Recombinant wild-type TFF1 significantly inhibited cell growth; A10D and E13K lost this tumor-suppressive property along with the ability to block etoposide-induced apoptosis. Although wild-type TFF1 promoted cell invasion, A10D and E13K were even more pro-invasive. Invasion induced by both mutants was blocked by inhibiting PI3-kinase or phospholipase-C, but inhibiting Rho-associated kinase (ROCK) blocked only E13K-induced invasion.

CONCLUSIONS

The loss of tumor-suppressor activity and gain of invasiveness from single point mutations constitute evidence for a functional role of TFF1 mutations in gastric cancer. These site-directed mutagenesis experiments provide the tools for continued probing of signal transduction mechanisms and structural elements responsible for TFF1 functions.

Early-onset gastric cancers have a different molecular expression profile than conventional gastric cancers

Many studies examine the molecular genetics of gastric cancer, but few look at young patients in particular and there is no comparison of molecular expression between early-onset gastric cancer (< or = 45 years old) and conventional gastric cancers. Expression of cycloxygenase-2 (COX-2) is elevated in gastric adenocarcinomas compared to non-neoplastic mucosa, and in light of studies showing reduced risk of gastric cancer in nonsteroidal anti-inflammatory drug users, we have chosen to investigate the expression of COX-2 and related molecules in 113 early-onset gastric cancers and compare it with 91 conventional gastric cancers, using tissue microarrays. These markers include molecules known to be important in conventional gastric carcinogenesis, such as E-Cadherin, p53, COX-2, Trefoil Factor-1 (TFF1), beta-catenin, p16 and c-myc; as well as molecules not yet described as being important in gastric cancer, such as the transcription factor c-jun, the COX-2 mRNA stabilizer HuR, and C/EBP-beta, a transcription factor for COX-2. All markers showed a statistically significant difference between early-onset gastric cancers and conventional gastric cancers, using a chi2 test. In particular, early-onset gastric cancers displayed a COX-2 Low, TFF1-expressing phenotype, whereas COX-2 overexpression and loss of TFF1 was found in conventional cancers, and this difference between early-onset gastric cancers and conventional cancers remained statistically significant when adjusted for location and histology (P<0.0001 and P = 0.002 respectively). We found that COX-2 overexpression correlates significantly with loss of TFF1 (P = 0.001), overexpression of C/EBP-beta (P<0.001) and cytoplasmic HuR (P = 0.016). COX-2 was significantly associated with p53 positivity (P = 0.003). Abnormalities in E-Cadherin correlated significantly with diffuse phenotype, whereas high expression of COX-2, loss of TFF1 and overexpression of C/EBP-beta correlated with the intestinal phenotype. Our results provide further evidence that early-onset gastric cancer exhibits a distinctive expression profile that may have practical implications.

Pathology and molecular biology of gastric cancer

Several attempts to classify gastric cancer (GCA) have been made over the past decades. Most successful, and widely used, is the classification by Laurén, which distinguishes, by microscopical morphology alone, two main cancer pathogeneses, diffuse (DGCA) and intestinal (IGCA) subtypes, which appear clearly as dissimilar clinical and epidemiological entities. Here we review the main differences in epidemiology, histopathology, and molecular pathology of the two main subtypes of gastric carcinomas based on Laurén classification. In clinical practice, however, clinical staging, particularly in predicting the survival, still remains superior to all classifications of gastric cancer independent of cancer type. The existence of local precursor lesions or conditions of IGCA tumours, i.e. Helicobacter pylori gastritis, atrophic gastritis (AG), intestinal metaplasia (IM), adenoma, dysplasia, and intramucosal neoplasia, is firmly established. The links of DGCA with intestinal-type epithelium, AG or IM are poor, or do not exist. So far, H. pylori gastritis is the only universal precursor condition for DGCA. It implies that AG and achlorhydria are of minor significance and infrequent in the development of DGCA but are important steps in that of IGCA. Despite an increasing body of data, the overall view on molecular pathology of GCA remains fragmentary. No consistent differences in the molecular pathology of GCA subtypes to meet the Laurén classification have been established. With the exception of TP53, no gene mutation occurring regularly in both histological types of GCA has been reported. Chromosomal aberrations and loss of heterozygosity seem to be non-specific and do not follow any consistent route in the progression of GCA. Microsatellite instability is more commonly found in IGCA than in DGCA. The present epigenetic data suggest that most of the decrease (or loss) of gene expression may be explained by promoter hypermethylation which is more often found in IGCA. In DGCA specific genes such as CDH1 are more often hypermethylated. Compared with GCA, in premalignant condition lesions gene mutations and chromosomal aberrations are infrequent. Epigenetic dysregulation might also represent a major mechanism for altered gene expression in premalignant stages in gastric carcinogenesis.

Trefoil factor family-3 is associated with aggressive behavior of colon cancer cells

BACKGROUND AND AIM

Trefoil factor family 3 (TFF3) is expressed by intestinal epithelial cells and it mainly functions to protect the mucosa from injury. Expression of TFF3 has been correlated with a poor prognosis in patients with cancer, but little is known about whether TFF3 directly contributes to the malignant behavior of cancer cells. The present study was conducted to determine whether TFF3 expression contributes to the malignant behavior of cancer cells in vitro and in vivo.

METHODS

Two subclones of a metastatic rat colorectal cancer cell line, demonstrated previously to manifest aggressive (LN cells) and non-aggressive (LP cells) growth in vivo, were analyzed for expression of TFF3 and tested in assays of cancer cell migration, invasion, and apoptosis in vitro, and mortality in vivo.

RESULTS

The aggressive LN cell line endogenously expressed TFF3 and supported the transcription of a TFF3 promoter-driven reporter construct, whereas the non-aggressive LP cell line did not express TFF3. LN cells demonstrated enhanced migration, invasion, and less apoptosis compared to LP cells. Transfecting TFF3 into LP cells enhanced their ability to migrate, invade, block apoptosis, and behave more aggressively in vivo, thereby resembling the phenotype of LN cells.

CONCLUSIONS

In rat colon cancer cells, both endogenous and constitutive expression of TFF3 correlates with an aggressive phenotype. These data provide direct evidence that TFF3 contributes to the malignant behavior of cancer cells.

Intestinal trefoil factor promotes invasion in non-tumorigenic Rat-2 fibroblast cell

Intestinal trefoil factor (TFF3) is essential in regulating cell migration and maintaining mucosal integrity in gastrointestinal tract. We previously showed that TFF3 was overexpressed in gastric carcinoma. Whether TFF3 possesses malignant potential is not fully elucidated. We sought to investigate the effects of inducting TFF3 expression in a non-malignant rat fibroblast cell line (Rat-2) on the cell proliferation, invasion and the genes regulating cell invasion. Invasiveness and proliferation of transfected Rat-2 cell line were assessed using in vitro invasion chamber assay and colorimetric MTS assay. Differential mRNA expressions of invasion-related genes, namely, metalloproteinases (MMP-9), tissue inhibitors of metalloproteinases (TIMP-1), beta-catenin and E-cadherin, were determined by quantitative real-time polymerase chain reaction (PCR). We showed that TFF3 did not inhibit the proliferation of Rat-2 cells. We also demonstrated that transfection of TFF3 significantly promoted invasion of Rat-2 cells by 1.4- to 2.2-folds. There was an upregulation of beta-catenin (13.1-23.0%) and MMP-9 (43.4-92.2%) mRNA expression levels, and downregulation of E-cadherin (25.6-33.8%) and TIMP-1 (31.5-37.8%) in TFF3-transfected cells compared to controls during 48-h incubation. Our results suggested that TFF3 possesses malignant potential through promotion of cell invasiveness and alteration of invasion-related genes.

Altered expression of TFF-1 and CES-2 in Barrett's Esophagus and associated adenocarcinomas

Identification of biomarkers to recognize individuals with Barrett's esophagus (BE) predisposed to develop malignancy is currently a pressing issue. We utilized gene expression profiling to compare molecular signatures of normal esophagus and stomach, BE, and adenocarcinoma (AC) to identify such potential biomarkers. Over 22,000 genes were analyzed by oligonucleotide microarrays on 38 unique RNA Unsupervised and supervised clusterings were performed on a subset of 2849 genes that varied most significantly across the specimens. Immunohistochemistry (IHC) for two of the significantly differentially expressed gene products was performed on tissue microarrays. Unsupervised clustering identified two discernable molecular BE profiles, one of which was similar to normal gastric tissue ("BE1"), and another that was shared by several of the AC specimens ("BE2"). The BE1 profile included expression of several genes that have been described as tumor-suppressor genes, most notably trefoil factor 1 (TFF-1). The BE2 profile included expression of genes previously found overexpressed in cancers, such as carboxylesterase-2 (CES-2). IHC demonstrated the loss of TFF-1 late in the progression of BE to AC. It also revealed CES-2 as being upregulated in AC documented to have arisen in the presence of BE. These potential biomarkers, as well as the relative expression of genes from BE1 versus those from BE2, may be validated in the future to aid in risk stratification and guide treatment protocols in patients with BE and associated AC.

Gene deregulation in gastric cancer

Despite its decreasing frequency in the Western world during recent decades, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Due to the oligosymptomatic course of early gastric cancer, most cases are diagnosed in the advanced stages of the disease. The curative potential of current standard treatment continues to be unsatisfactory, despite multimodal approaches involving surgery, chemotherapy and radiotherapy. Novel therapeutics including small molecules and monoclonal antibodies are being developed and have been partially introduced into clinical use in connection with neoplastic diseases such as chronic myeloid leukemia, non-Hodgkin's lymphoma and colorectal cancer. Thorough understanding of the changes in gene expression occurring during gastric carcinogenesis may help to develop targeted therapies and improve the treatment of this disease. Novel molecular biology techniques have generated a wealth of data on up- and down-regulation, activation and inhibition of specific pathways in gastric cancer. Here, we provide an overview of the different aspects of aberrant gene expression patterns in gastric cancer.

Gastric achlorhydria in H/K-ATPase-deficient (Atp4a(-/-)) mice causes severe hyperplasia, mucocystic metaplasia and upregulation of growth factors

BACKGROUND

Gastric neoplasia is common in humans, yet controversy remains over contributions of chronic achlorhydria, gastrinemia and hyperplasia, to cancer risk. To study this, mice lacking the gastric H/K-ATPase (Atp4a(-/-) mice) were used to determine whether chronic loss of acid secretion, with attendant hypergastrinemia, predisposes to cancer phenotype.

METHODS

Atp4a(-/-) and Atp4a(+/+) mice, paired for age and gender, were examined at 3, 8, 12 and 20 months for histopathology, and for expression of the trefoil factor family (TFF)1-3, Reg IIIbeta, gamma and delta, osteopontin, CD44, chromogranin A, Crp-ductin, and galectin, all of which are important in cell growth.

RESULTS

By 8 months, the glandular stomach of the Atp4a(-/-) mice doubled in weight and thickness, and several modulators of growth were increased. Female Atp4a(-/-) mice were more hyperplastic than Atp4a(-/-) males at 12 and 20 months. By 1 year, severe mucocystic hyperplasia, incomplete intestinal metaplasia, ciliated metaplasia, a shift in mucins from neutral to acidic, and inflammation were widespread. Cells in the mucus pit zone developed a pyloric-type appearance, containing large hyaline-like, periodic acid-Schiff (PAS)-negative/alcian blue-negative inclusions. But critical characteristics of gastric neoplasia, such as nuclear atypia, invasion into the muscularis mucosa, and metastases were absent. In Atp4a(-/-) mice, chromogranin A and histidine decarboxylase, RegIIIgamma and delta, TFF3, osteopontin and CD44 were upregulated while Reg IIIbeta, and TFF1 were reduced.

CONCLUSIONS

Chronic achlorhydria and hypergastrinemia in aged Atp4a(-/-) mice produced progressive hyperplasia, mucocystic and incomplete intestinal metaplasia, and the upregulation of growth factors without histological evidence of neoplasia.

Multidisciplinary approach to understand the pathogenesis of gastric cancer

Gastric carcinoma remains a common disease worldwide with a dismal prognosis. Therefore, it represents a very important health problem. It occurs with a high incidence in Asia and is one of the leading causes of cancer death in the world. Although the incidence and mortality of gastric carcinoma are decreasing in many countries, gastric cancer still represents the second most frequent malignancies in the world and the fourth in Europe. The 5-year survival rate of gastric carcinoma is low. The etiology and pathogenesis are not yet fully known. The study of gastric cancer is important in clinical medicine as well as in public health. Over the past 15 years, integrated research in molecular pathology has clarified the details of genetic and epigenetic abnormalities of cancer-related genes in the course of the development and progression of gastric cancer. Gastric cancer, as all cancers, is the end result of the interplay of many risk factors as well as protective factors. Although epidemiological evidence indicates that environmental factors play a major role in gastric carcinogenesis, the role of immunological, genetic, and immunogenetic factors are thought to contribute to the pathogenesis of gastric carcinoma. Among the environmental factors, diet and Helicobacter pylori are more amenable to intervention aimed at the prevention of gastric cancer. The aim of the present paper is to review and include the most recent published evidence to demonstrate that only a multidisciplinary approach will lead to the advancement of the pathogenesis and prevention of gastric cancer. On the immunogenetic research it is clear that evidence is accumulating to suggest that a genetic profile favoring the proinflammatory response increases the risk of gastric carcinoma.

Increased expression of histone deacetylase 2 is found in human gastric cancer

Accumulated evidence has established that aberrant regulation of histone deacetylases (HDACs) is one of the major causes of the development of human malignancies. Among different iso-enzymes of HDAC and sirtuins grouped as the HDAC super family, little is known as to how histone deacetylase 2 (HDAC2) causes carcinogenesis in solid tumors. Here, in order to investigate the possible role of HDAC2 in gastric carcinogenesis, we analyzed the expression of HDAC2 in 71 gastric adenocarcinomas by immunohistochemistry. Moderate to strong expression of HDAC2 was found in 44 (62%) out of a total of 71 tumors. The majority of positive tumors, which were detected in the nucleus but not in normal gastric epithelium, did not express HDAC2 or showed only weak positive staining. Interestingly, we also noted that HDAC2 expression appeared to be associated with tumor aggressiveness as HDAC2 expression was observed to be statistically significant in advanced gastric cancer (P=0.0023, Chi-square test) and in positive lymph node metastasis (P=0.0713, Chi-square test). Taken together, these results suggest that HDAC2 may play an important role in the aggressiveness of gastric cancer.

Gene Expression Profiling to Identify Oncogenic Determinants of Autocrine Human Growth Hormone in Human Mammary Carcinoma

We have exploited a discrepancy in the oncogenic potential of autocrine and exogenous human growth hormone (hGH) in an attempt to identify molecules that could potentially be involved in oncogenic transformation of the human mammary epithelial cell. Microarray analysis of 19,000 human genes identified a subset of 305 genes in a human mammary carcinoma cell line that were remarkably different in their response to autocrine and exogenous hGH. Autocrine and exogenous hGH also regulated 167 common genes. Semiquantitative reverse transcription-PCR confirmed differential regulation of genes by either autocrine or exogenous hGH. Functional analysis of one of the identified autocrine hGH-regulated genes, TFF3, determined that its expression is sufficient to support anchorage-independent growth of human mammary carcinoma cells. Small interfering RNA-mediated knockdown of TFF3 concordantly abrogated anchorage-independent growth of mammary carcinoma cells and abrogated the ability of autocrine hGH to stimulate oncogenic transformation of immortalized human mammary epithelial cells. Further functional characterization of the identified subset of specifically autocrine hGH regulated genes will delineate additional novel oncogenes for the human mammary epithelial cell.

Transcriptional repression of TFF1 in gastric epithelial cells by CCAAT/enhancer binding protein-beta

TFF1 is a member of a unique family of gastrointestinal peptides. Loss of TFF1 expression has been observed in the majority of human gastric cancers and the biological significance of this loss has been demonstrated in a Tff1 knockout mouse model. However, few TFF1 gene mutations or allelic loss have also been documented. To understand the molecular mechanism repressing the TFF1 gene expression, the 5'-flanking region of the human TFF1 gene was characterized. We found a repressor region (-241 to -84), which is active in MKN45 and IMGE5 cells expressing endogenous TFF1 gene. A consensus binding site for C/EBPbeta was identified and EMSA analysis demonstrated specific binding of CEBPbeta. Mutation of this C/EBPbeta element potentiated the transactivation of TFF1 by 50% and 145% for MKN45 and IMGE5 cells respectively. Furthermore, co-transfection of C/EBPbeta isoforms specifically decreased TFF1 promoter activity. These findings suggest that C/EBPbeta is involved in the down-regulating of TFF1 gene expression and this mode of repression may account at least in part for the loss of TFF1 gene expression in transformed human and mice gastric epithelial cells.

Anti-sense trefoil factor family-3 (intestinal trefoil factor) inhibits cell growth and induces chemosensitivity to adriamycin in human gastric cancer cells

Intestinal trefoil factor (ITF), which is normally absent in gastric mucosa, is over-expressed in gastric cancer. However, the functional significance of ITF in gastric cancer is unknown. We examined the effects of blocking ITF expression on the growth of gastric cancer cells and their responses to chemotherapeutic agents. Anti-sense ITF cDNA was cloned into mammalian expression vector pcDNA3 and was transfected into an ITF-expressing gastric cancer cell line SNU-1. We assessed the doubling time and anchorage dependent growth of the transfected cells using growth curve and soft agar assay respectively. Cell cycle analysis and apoptosis were determined by flow cytometry and cell death ELISA. The response to chemotherapeutic agents after transfecting anti-sense ITF was also examined. Anti-sense ITF transfectant (3A-5) had a significantly longer doubling time as compared to control cells which were transfected with empty vector (32.4 hr vs 26.9 hr, p < 0.05). In the soft agar assay, 3A-5 formed fewer colonies than control (3.5 colonies vs 23.5 colonies, p < 0.05). Although there was no significant difference in the cell cycle distribution between 3A-5 and control, anti-sense ITF resulted in marked increase in adriamycin-induced apoptosis. Our results demonstrated that blocking the expression of ITF inhibits growth of gastric cancer cells and enhances the response to chemotherapy.

Gene cataloging and expression profiling in human gastric cancer cells by expressed sequence tags

To understand the molecular mechanism associated with gastric carcinogenesis, we identified genes expressed in gastric cancer cell lines and tissues. Of 97,609 high-quality ESTs sequenced from 36 cDNA libraries, 92,545 were coalesced into 10,418 human Unigene clusters (Build 151). The gene expression profile was produced by counting the cluster frequencies in each library. Although the profiles of highly expressed genes varied greatly from library to library, those genes related to cell structure formation, heat shock proteins, the glycolysis pathway, and the signaling pathway were highly represented in human gastric cancer cell lines and in primary tumors. Conversely, the genes encoding immunoglobulins, ribosomal proteins, and digestive proteins were down-regulated in gastric cancer cell lines and tissues compared to normal tissues. The transcription levels of some of these genes were confirmed by RT-PCR. We found that genes related to cell adhesion, apoptosis, and cytoskeleton formation were particularly up-regulated in the gastric cancer cell lines established from malignant ascites compared to those from primary tumors. This comprehensive molecular profiling of human gastric cancer should be useful for elucidating the genetic events associated with human gastric cancer.

Identification of Gastric Cancer–Related Genes Using a cDNA Microarray Containing Novel Expressed Sequence Tags Expressed in Gastric Cancer Cells

Purpose: Gastric cancer is one of the most frequently diagnosed malignancies in the world, especially in Korea and Japan. To understand the molecular mechanism associated with gastric carcinogenesis, we attempted to identify novel gastric cancer–related genes using a novel 2K cDNA microarray.

Experimental Design: A 2K cDNA microarray was fabricated from 1,995 novel expressed sequence tags (ESTs) showing no hits or a low homology with ESTs in public databases from our 143,452 ESTs collected from gastric cancer cell lines and tissues. An analysis of the gene expression for human gastric cancer cell lines to a normal cell line was done using this cDNA microarray. Data for the different expressed genes were verified using semiquantitative reverse transcription-PCR, Western blotting, and immunohistochemical staining in the gastric cell lines and tissues.

Results: Forty genes were identified as either up-regulated or down-regulated genes in human gastric cancer cells. Among these, genes such as SKB1, NT5C3, ZNF9, p30, CDC20, and FEN1, were confirmed to be up-regulated genes in nine gastric cell lines and in 25 pairs of tissue samples from patients by semiquantitative reverse transcription-PCR. On the other hand, genes such as MT2A and CXX1 were identified as down-regulated genes. In particular, the SKB1, CDC20, and FEN1 genes were overexpressed in ≥68% of tissues and the MT2A gene was down-expressed in 72% of the tissues. Western blotting and immunohistochemical analyses for CDC20 and SKB1 showed overexpression and localization changes of the corresponding protein in human gastric cancer tissues.

Conclusions: Novel genes that are related to human gastric cancer were identified using cDNA microarray developed in our laboratory. In particular, CDC20 and MT2A represent a potential biomarker of human gastric cancer. These newly identified genes should provide a valuable resource for understanding the molecular mechanism associated with tumorigenesis of gastric carcinogenesis and for the discovery of potential diagnostic markers of gastric cancer.

Molecular biology of gastric cancer: Helicobacter infection and gastric adenocarcinoma: bacterial and host factors responsible for altered growth signaling

Gastric cancer remains the second most common cause of cancer-related mortality worldwide. The single most common cause of gastric cancer is chronic infection with the gram-negative microaerophilic spiral bacterium: Helicobacter pylori. Recent advances in this field have identified host factors which predispose to gastric cancer formation via modulation of the host immune response. In addition, recent work has explored bacterial virulence factors which may directly cause tissue damage, and lead to gastric carcinogenesis, as well as factors responsible for enhanced immune response. Environmental factors, long associated with a predilection for gastric cancer, are recognized as modifiers of key growth signalling pathways within the gastric mucosa and as such lead to growth alterations. This review focuses on exploring new advances in our understanding of bacterial factors, host genetic polymorphisms and the interaction between the bacterium and host at the level of the immune response and the regulation of proliferative and apoptotic signal transduction cascades. Modulation of the pivotal balance between cell growth and cell death leads to the formation of gastric adenocarcinoma.

Comparison of gene-expression profiles between diffuse- and intestinal-type gastric cancers using a genome-wide cDNA microarray

Gastric cancer is the fourth leading cause of cancer-related death in the world. Two histologically distinct types of gastric carcinoma, 'intestinal' and 'diffuse', have different epidemiological and pathophysiological features that suggest different mechanisms of carcinogenesis. A number of studies have investigated intestinal-type gastric cancers at the molecular level, but little is known about mechanisms involved in the diffuse type, which has a more invasive phenotype and poorer prognosis. To clarify the mechanisms that underlie its development and/or progression, we compared the expression profiles of 20 laser-microbeam-microdissected diffuse-type gastric-cancer tissues with corresponding noncancerous mucosae by means of a cDNA microarray containing 23,040 genes. We identified 153 genes that were commonly upregulated and more than 1500 that were commonly downregulated in the tumors. We also identified a number of genes related to tumor progression. Furthermore, comparison of the expression profiles of diffuse-type with those of intestinal-type gastric cancers identified 46 genes that may represent distinct molecular signatures of each histological type. The putative signature of diffuse-type cancer exhibited altered expression of genes related to cell-matrix interaction and extracellular-matrix (ECM) components, whereas that of intestinal-type cancer represented enhancement of cell growth. These data provide insight into different mechanisms underlying gastric carcinogenesis and may also serve as a starting point for identifying novel diagnostic markers and/or therapeutic targets for diffuse-type gastric cancers.

Altered expression of KCNK9 in colorectal cancers

K(+) channels have been reported to be involved in the proliferation of many types of cells, including some human carcinoma and tumor cell lines. KCNK9, a TASK channel, is amplified and overexpressed in several types of human cancer. In the present study, we examined the expression and somatic mutations of KCNK9 in 124 colorectal cancers by immunohistochemistry using tissue microarray and PCR-SSCP. Immunopositivity was observed in 57 (46.0%) of 124 colorectal cancers. Clinically, KCNK9 was immunopositive in 4 (30.7%) of 13 cases which were stage A, 26 (55.3%) of 47 which were stage B, 23 (41.1%) of 56 which were stage C, and 4 (50%) of 8 which were stage D. Statistically, KCNK9 protein expression was not related to tumor stage (Bartholomew test, p>0.05) and lymph node metastasis (Chi-Square test, p=0.8338). In the mutation study of the KCNK9 gene, we found only one sequence variation (ACG-->ACC, Thr-->Thr) at codon 170 both in corresponding normal and tumor DNAs. These results indicate that overexpression rather than mutation of the KCNK9 gene may contribute to the development of colorectal cancers and suggest that the development of KCNK9-targeted agents may provide new possibilities in the treatment of colorectal cancer.

Decrease of deleted in malignant brain tumour-1 (DMBT-1) expression is a crucial late event in intrahepatic cholangiocarcinoma

AIMS

To investigate the participation of DMBT-1, a candidate tumour suppressor gene, in the development of intrahepatic cholangiocarcinoma via intraductal papillary neoplasm of the liver (IPN-L) arising in hepatolithiasis. DMBT-1 plays a role in mucosal immune defence.

METHODS AND RESULTS

The expression of DMBT-1 was examined immunohistochemically in biliary epithelial cells in hepatolithiasis (n = 25), invasive and non-invasive cholangiocarcinoma associated with hepatolithiasis (n = 52), IPN-L with hepatolithiasis (n = 49), cholangiocarcinoma without hepatolithiasis (n = 32), and 10 normal control livers. DMBT-1 was expressed more frequently in the biliary epithelia of hepatolithiasis when compared with normal livers (P < 0.05). DMBT-1 expression was also frequent in IPN-L (57%) and non-invasive cholangiocarcinoma (79%). By contrast, DMBT-1 was decreased in invasive cholangiocarcinoma with and without hepatolithiasis (50% and 30%, respectively) (P < 0.05). The homozygous deletion of the DMBT-1 gene was recognized in four (20%) of 20 cholangiocarcinoma tissues and two (50%) of four cholangiocarcinoma cell lines, corresponding to the reduction of DMBT-1 expression. No deletion was detected in hepatolithiasis tissues.

CONCLUSION

DMBT-1 expression is increased in IPN-L and non-invasive cholangiocarcinoma as well as in biliary epithelia in hepatolithiasis. Decreased expression of DMBT-1 and homozygous deletion of the DMBT-1 gene in invasive cholangiocarcinoma suggest that they occur in the late stage of cholangiocarcinogenesis.

Trefoil factor family (TFF) peptides and cancer progression

TFF peptides are involved in mucosal maintenance and repair through motogenic and antiapoptotic activities. These peptides are overexpressed during inflammatory processes and cancer progression. They also function as scatter factors, proinvasive and angiogenic agents. Such a divergence is related to the pathophysiological state of tissues submitted to persistent aggressive situations during digestive processes in the normal gastrointestinal tract, inflammatory and neoplastic diseases. In agreement with this model, TFF peptides are connected with multiple oncogenic pathways. As a consequence, the TFF signaling pathways may serve as potential targets in the control of chronic inflammation and progression of human solid tumors.

Expression of trefoil peptides in the subtypes of intestinal metaplasia

We studied the expression of trefoil peptides in the different types of intestinal metaplasia of the stomach. Endoscopic biopsy was performed in 132 patients with dyspepsia. Intestinal metaplasia subtype was classified according to the pattern of alcian blue/PAS staining and high iron diamine staining. Expression of trefoil peptides was measured by immunohistochemistry. TFF1 and TFF3 were mainly expressed in goblet cells and TFF2 in columnar cells in all the types of intestinal metaplasia. There was a gradual decrease of TFF1 and TFF3, and increase of TFF2, during the progression of intestinal metaplasia from type I to type III via the type II intermediate.

Profiling trefoil factor family (TFF) expression in the mouse: identification of an antisense TFF1-related transcript in the kidney and liver

The expression of the trefoil factor family (TFF) genes (TFF1, TFF2, and TFF3) was systematically analyzed in 18 different organs from male or female mice using RT-PCR analysis. The expression patterns showed some gender-specific differences, e.g., TFF3 transcripts in the urinary bladder and liver. Furthermore, the murine expression profile differed from that in human, e.g., in the respiratory tract and uterine cervix. As a hallmark, an aberrant TFF1-related transcript was detected specifically in the kidney and liver of several mouse strains. Molecular characterization of this rare 1.8kb long transcript from the kidney clearly revealed that its 3' region originated from the antisense strand of the TFF1 locus containing particularly large parts of the antisense strands of introns 1 and 2. Homology searches using various databases revealed that this antisense TFF1-related transcript is subject of intense alternative splicing and no protein product encoded by this antisense TFF1-related transcript could be identified. Although the function of this transcript is not known currently, we can speculate that this antisense TFF1-related transcript might have a gene silencing effect particularly on TFF1 expression in the murine kidney and liver.

Urinary pS2/TFF1 levels in the management of hormonodependent breast carcinomas

pS2/TFF1 overexpression in breast carcinomas correlates with response to hormonotherapy. We evaluated the clinical relevance of urinary pS2/TFF1 in breast cancer patients. In healthy controls (100 cases), it represents an individual and relatively stable parameter. Although 24 out 83 pre-operative breast cancer patients showed elevated levels, both the sensitivity and specificity of the test were too low for breast cancer screening. However, neoadjuvant hormonotherapy decreased pS2/TFF1 levels in nine out of 20 patients. Furthermore, among 22 patients receiving long-term adjuvant hormonotherapy, four exhibited elevated levels, two of them at the time of relapse. Thus, urinary pS2/TFF1 quantification might be suitable as an in vivo diagnosis for tumor hormonodependency, and disease follow-up during hormonotherapy.

Helicobacter pyloriet cancer gastrique

Gastric cancer is a worldwide cancer especially frequent in Japan and South America. This cancer affects 10 to 70 people per 100,000 according to the countries. Since the end of the Second World War, the incidence of gastric cancer has been decreasing in France and accounts for less than 10 % of mortality. Helicobacter pylori infection, host genetic background, food regimen are known to be involved in this cancer. Helicobacter pylori should be eradicated in selected patients, such as patients' relatives with documented gastric cancer as well as patients having another gastrointestinal cancer.

Gastric cancer development in mice lacking the SHP2 binding site on the IL-6 family co-receptor gp130

BACKGROUND AND AIMS

We have developed a mouse model of gastric cancer that resembles human intestinal-type adenocarcinoma. The aim of this study was to determine the identity and temporal changes in mediators of IL-6 signaling regulating tumor development.

METHODS

gp130(757F/F) Mice that lack the SHP2-binding site on the IL-6 family receptor gp130 and have increased STAT 3 activity and wild-type littermates were used. Cohorts were assessed by quantitative histology and immunohistochemistry for gastric cell phenotype and proliferation markers from 4 to 40 weeks of tumor development. Northern blotting and in situ hybridization were used to quantify expression of the tumor suppressor TFF1 and the mitogens gastrin and Reg I. Expression of epidermal growth factor receptor (EGFr) and its ligands was measured by RT-PCR analysis. Age-matched differences in gene expression profiles were tested by ANOVA.

RESULTS

Hyperplastic antral tumors with inflammation and ulceration were evident in gp130(757F/F) mice at 4 weeks of age and reached maximum size by 20 weeks. Tumor progression was marked by gastritis, atrophy, intestinal metaplasia, dysplasia, and submucosal invasion after 30 weeks. Both TFF1 and gastrin expression were progressively inhibited during tumorigenesis, whereas Reg I was stimulated. The EGFr and its ligands transforming growth factor (TGF)-alpha and heparin-binding EGF had increased expression corresponding to maximal tumor growth.

CONCLUSIONS

gp130(757F/F) Mice rapidly develop distal stomach tumors, with loss of SHP2/Erk/AP-1 transcriptional regulation exemplified by decreased TFF1 expression and increased STAT1/3 regulated genes such as Reg I. Tumor development occurs in a hypogastrinemic environment. Balanced IL-6 signaling is required for maintaining gastric homeostasis.

GATA-4 and GATA-5 transcription factor genes and potential downstream antitumor target genes are epigenetically silenced in colorectal and gastric cancer

The GATA family of transcription factors participates in gastrointestinal (GI) development. Increases in GATA-4 and -5 expression occur in differentiation and GATA-6 expression in proliferation in embryonic and adult settings. We now show that in colorectal cancer (CRC) and gastric cancer promoter hypermethylation and transcriptional silencing are frequent for GATA-4 and -5 but are never seen for GATA-6. Potential antitumor target genes upregulated by GATA-4 and -5, the trefoil factors, inhibinalpha, and disabled-2 (Dab2) are also silenced, in GI cancers, with associated methylation of the promoters. Drug or genetically induced demethylation simultaneously leads to expression, in CRC cells, of all of the GATA-4, -5, and downstream genes. Expression of exogenous GATA-5 overrides methylation at the downstream promoters to activate the target genes. Selection for silencing of both upstream transcription factors and their target genes in GI cancers could indicate that epigenetic silencing of the involved genes provides a summated contribution to tumor progression.

Helicobacter and gastric cancer disease mechanisms: host response and disease susceptibility

Helicobacter infection is the single most common cause of gastric cancer worldwide. Although infection prevention and eradication of established infection offer the potential for cure, these strategies are neither feasible nor practical for widespread implementation. Patients most at risk need to be identified and targeted for treatment. For disease to occur, bacterial, environmental, and nutritional factors require a genetically susceptible host. Consequently, it is important to understand how the organism interacts with the host to cause disease. Only through an understanding of what places a patient at risk can we hope to identify susceptible patients early enough in disease to have an impact on their outcome. The immune response is the single most important determinant of disease. Single nucleotide polymorphisms within the promoter region of several critical proinflammatory genes dramatically increase the risk of Helicobacter-associated gastric cancer. Additionally, environmental and dietary factors may modulate the immune response or directly influence key apoptotic and proliferative signaling cascades to alter disease presentation. Lastly, concurrent disease states may have a dramatic impact on the host response to Helicobacter infection and influence disease. An understanding of the immune signaling pathways responsible for disease and the ways in which environmental risk factors influence these pathways will allow identification of populations that are most at risk and targeted prevention and treatment strategies.

Decreased abundance of trefoil factor 1 transcript in the majority of gastric carcinomas

BACKGROUND

Gastric carcinoma is one of the leading causes of cancer-related death worldwide, but the mechanisms underlying its development and progression still remain largely uncharacterized. As loss of trefoil factor 1 (TFF1) expression leads to neoplastic growth in the antropyloric mucosa of mice, the authors sought to comprehensively study the human TFF1 gene in primary gastric carcinomas.

METHODS

The authors studied the human TFF1 gene in primary gastric carcinomas and normal gastric mucosa at the DNA, RNA, and protein levels through DNA sequencing, quantitative real-time reverse transcriptase-polymerase chain reaction, and immunohistochemistry.

RESULTS

Strikingly, TFF1 mRNA expression was significantly decreased in all 37 gastric carcinomas studied compared with normal gastric mucosa. Furthermore, six tumor/normal pairs with available histologic samples demonstrated a marked decrease in protein expression in tumor samples. Screening of the entire TFF1 coding region in a panel of 42 human gastric tumors did not reveal any somatic mutations, although a few rare germline sequence variants were identified.

CONCLUSIONS

These findings demonstrated a significant decrease in the TFF1 transcript in the majority of human gastric carcinomas along with a corresponding reduction in protein expression, both of which occurred in the absence of gene mutation. Dysregulation of TFF1 expression at the transcript level was a critical event in the development of most gastric carcinomas.

Trefoil factors: initiators of mucosal healing

Maintaining the integrity of the gastrointestinal tract, despite the continual presence of microbial flora and injurious agents, is essential. Epithelial continuity depends on a family of small, yet abundant, secreted proteins--the trefoil factors (TFFs). TFFs protect mucous epithelia from a range of insults and contribute to mucosal repair, although the signalling events that mediate these responses are only partially understood.

Aberrant expression of trefoil factor family 1 in biliary epithelium in hepatolithiasis and cholangiocarcinoma

Stepwise progression of intrahepatic cholangiocarcinoma (ICC) has been proposed in hepatolithiasis. We examined the participation of trefoil factor family 1 (TFF1), which is critical for mucosal protection and tumor suppression in the stomach, in the development and progression of ICC. We used 16 livers of ICC with hepatolithiasis, 11 of biliary epithelial dysplasia with hepatolithiasis, 16 of hepatolithiasis without dysplasia or carcinoma, 18 of ICC without hepatolithiasis, and 39 control livers. TFF1 expression in the biliary epithelium was increased in hepatolithiasis compared with control livers (p < 0.01). In biliary epithelial dysplasia and noninvasive ICC with hepatolithiasis, TFF1 was extensively expressed and MUC5AC gastric mucin was usually colocalized with TFF1. However, TFF1 expression was significantly decreased in invasive ICC despite preserved expression of MUC5AC. A total of four missense mutations were detected: three in two noninvasive ICC with hepatolithiasis (28.6%) and one in invasive ICC (11%). Loss of heterozygosity of the TFF1 gene was not detectable. The decreased expression of TFF1 in invasive ICC may be explained by the methylation of the TFF1 promoter region. Up-regulation of TFF1 coupled with MUC5AC in biliary epithelium in hepatolithiasis, biliary epithelial dysplasia, and noninvasive ICC may reflect the gastric metaplasia and early neoplastic lesion. Under such conditions, decreased TFF1 expression may lead to increased cell proliferation and then to the invasive character of ICC.

Expression of cytoplasmic TFF2 is a marker of tumor metastasis and negative prognostic factor in gastric cancer

Trefoil factor family 2 (TFF2) is a small peptide constitutively expressed in the gastric mucosa, where it plays a protective role in restitution of gastric mucosa. TFF2 has also been shown to be expressed in some gastric cancers, but its role in tumor metastasis and patient prognosis has not been examined. In this study, we examined TFF2 expression at both the mRNA and protein levels and correlated these results with the clinicopathologic characteristics and prognosis of gastric cancer patients. Among the 144 curatively resected samples, 43 (30%) were positive for TFF2. TFF2 expression was preferentially observed in the infiltrating tumor cells sparing the superficial cells. Significantly increased expression of TFF2 was noted in large tumors of the diffuse type. An increased prevalence of TFF2 expression was also found in tumors with advanced T and N stage and in patients with lymphatic and venous invasion. Accordingly, patients with TFF2-expressing tumors had a significantly worse disease-free survival, and in multivariate analysis, this finding remained significant as an independent prognostic factor. Taken together, our results suggest that TFF2 expression may play a role in gastric cancer invasion and as such could be a useful target for therapeutic intervention.

Transcriptional regulation of the human trefoil factor, TFF1, by gastrin

BACKGROUND & AIMS

This study aimed to identify gastrin-sensitive genes that may mediate the effects of this hormone on gastric epithelial architecture.

METHODS

Gastrin-sensitive genes were identified by messenger RNA (mRNA) differential display of the gastric fundus from gastrin-deficient (GAS-KO) or wild-type mice. Gastrin-stimulated expression of the trefoil peptide TFF1 in mouse fundus and in the gastric cancer cell line AGS-G(R) was determined by Northern blot and real-time polymerase chain reaction. Transcriptional regulation of TFF1 in AGS-G(R) cells was studied using promoter-reporter assays and electrophoretic mobility shift assay. Expression of TFF1 and the cholecystokinin(B) receptor in response to gastric mucosal injury was determined by immunohistochemistry.

RESULTS

mRNA differential display identified TFF1 as a gastrin-regulated gene. TFF1 mRNA was reversibly reduced in GAS-KO mice and increased in a hypergastrinemic transgenic strain versus respective background strains. TFF1 mRNA expression was rapidly and potently induced by gastrin in a gastric cancer cell line that expresses the gastrin/cholecystokinin(B) receptor. Gastrin responsiveness of the human TFF1 promoter mapped to a G-C rich region 300 base pairs upstream of the transcriptional start site. This region bound the transcription factors SP3 and MAZ. Gastrin activated transcription through a Raf-, Mek- and Erk-dependent but Ras-independent pathway. TFF1 expression was induced both directly and by transactivation between neighboring cells. Neither direct nor indirect gastrin-induced TFF1 expression required activation of the epidermal growth factor receptor.

CONCLUSIONS

Gastrin exerts tonic control of TFF1 expression but also has the potential for rapid up-regulation of this trefoil factor. TFF1 is a potential candidate to counterbalance the proliferative effects of gastrin.

Analysis of gene expression profiles of gastric normal and cancer tissues by SAGE

In an attempt to understand the molecular bases of gastric cancer progression, we have analyzed the differentially expressed genes in gastric cancer by SAGE. Four SAGE cDNA tag libraries were constructed from two sets of gastric cancer and normal tissues and 241,127 tags were obtained. By comparing the tags from cancer and normal tissues, 414 differentially expressed tags, representing 383 genes, were identified in cancer tissues (p </= 0.01). Of the 414 tags, 50 tags were previously unidentified and potentially novel genes. Although each gastric cancer tissue revealed more than 200 differentially expressed genes compared to the respective normal tissue, the number of genes with consistent regulation patterns in both cancer tissues was 51: 12 up-regulated and 39 down-regulated genes. The genes that showed consistent regulation patterns included well-known genes such as Trefoil factor 3, RegIV, gastric intrinsic factor, and lactotransferrin as well as a few novel candidates. Interestingly, the expression of several genes, such as osteoglycin, prostate stem cell antigen, and histone deacetylase 3, was variable in the two normal tissues but similar in the cancer tissues. The expression profiles of these genes in normal tissues, possibly due to genetic background, could greatly affect individual sensitivity to cancer development and/or progression. The genes identified in this study will provide useful target genes for diagnosis and molecular treatment of gastric cancer.

Magnetic resonance imaging of gastric cancer in Tff1 knock-out mice

In this work, the use of MRI to stage gastric neoplasia in a mouse model of spontaneous gastric cancer is demonstrated. The methodology involves 1) the use of deuterated water ((2)H(2)O) to distend the stomach, and to provide negative contrast between the stomach and the lumen without inducing susceptibility-based field shifts; 2) GlucaGen to minimize motion artifacts that arise from peristalsis; and 3) Gd-DTPA to enhance contrast between the dysplasia/tumor and the normal wall. Initial images are presented from a Tff1 -/- homozygous knock-out model of gastric cancer and a heterozygous C57BL6/J control mouse. There are clear differences between the two types of animals in the MR appearance of the stomach. The distended stomach of the control mouse has a smooth perimeter and a thin wall, and an absence of nodules. The stomach of the Tff1 -/- mouse demonstrates a thickened wall; a jagged, irregular surface; and protruding nodules that are bright after injection of Gd-DTPA.

Role of therapy or monitoring in preventing progression to gastric cancer

It is generally accepted that intestinal-type gastric adenocarcinoma arises through a multistep process originating with chronic gastritis, progressing through stages of atrophy, intestinal metaplasia, and dysplasia and finally invasive carcinoma. This sequential process, known as the "Correa cascade" is in many instances initiated by Helicobacter pylori infection and perpetuated by a number of environmental and host factors. Given that the development of carcinoma can be the end point of this sequential process, there is great interest in determining which if any of these steps may be reversible. Clinical studies have shown that the eradication of H. pylori can lead to resolution of chronic gastritis, and a few studies have suggested some improvement in gastric atrophy. Intestinal metaplasia, however, does not appear to be as reversible. Nevertheless, results of several intriguing studies of high-risk populations support the notion that eradication of H. pylori may decrease or delay progression to gastric carcinoma despite the inability to reverse all mucosal damage. The applicability of these findings to low-risk countries such as the United States and the United Kingdom remain uncertain. Currently, in the United States, there is no widely accepted screening program for H. pylori infection in asymptomatic individuals, and consensus regarding surveillance for gastric intestinal metaplasia or dysplasia is lacking. The purpose of this report is to evaluate the available data regarding the epidemiology of H. pylori and associated carcinoma, discuss relevant human and animal data that address eradication strategies in the prevention of gastric carcinoma, and finally discuss current recommendations regarding screening programs aimed at high-risk populations.

Loss of heterozygosity and promoter methylation, but not mutation, may underlie loss of TFF1 in gastric carcinoma

It has been advanced that the trefoil factor (TFF) 1 gene is a candidate tumor-suppressor gene and may be involved in the development and/or progression of human gastric cancer. We aimed to clarify the putative role of TFF1 in gastric carcinogenesis. Ninety gastric carcinomas and eight gastric carcinoma-derived cell lines were screened for TFF1 mutations; subsets of the primary tumors and of the cell lines were subjected to loss of heterozygosity (LOH), immunohistochemistry, and promoter methylation analyses. TFF1 mutations were not detected in any of 90 gastric carcinomas. Eight (28%) of 28 informative cases displayed LOH at the TFF1 locus and absence of TFF1 staining by immunohistochemistry. These results indicate a frequent loss of TFF1 expression in gastric carcinomas through a mutation-independent mechanism. Extensive TFF1 promoter methylation was observed in nonexpressing gastric carcinoma-derived cell lines and tissues. Expressing cell lines, as well as normal gastric mucosa, presented little or no methylation of the promoter. Gastric carcinoma DNA presented de novo methylation of the promoter. These results point to the involvement of promoter methylation in the shutting down of TFF1. We conclude that TFF1 point mutations seem to be a rare event in gastric carcinogenesis. The loss of expression of TFF1 in a proportion of gastric carcinomas may be explained by LOH and methylation of the TFF1 promoter region. Our results further support the role of TFF1 inactivation in gastric carcinogenesis, in agreement with the results obtained in the Tff1-knockout mice model.

Reciprocal regulation of gastrointestinal homeostasis by SHP2 and STAT-mediated trefoil gene activation in gp130 mutant mice

The intracellular signaling mechanisms that specify tissue-specific responses to the interleukin-6 (IL-6) family of cytokines are not well understood. Here, we evaluated the functions of the two major signaling pathways, the signal transducers and activators of transcription 1 and 3 (STAT1/3) and the Src-homology tyrosine phosphatase 2 (SHP2)-Ras-ERK, emanating from the common signal transducer, gp130, in the gastrointestinal tract. Gp130(757F) mice, with a 'knock-in' mutation abrogating SHP2-Ras-ERK signaling, developed gastric adenomas by three months of age. In contrast, mice harboring the reciprocal mutation ablating STAT1/3 signaling (gp130(Delta STAT)), or deficient in IL-6-mediated gp130 signaling (IL-6(-/-) mice), showed impaired colonic mucosal wound healing. These gastrointestinal phenotypes are highly similar to the phenotypes exhibited by mice deficient in trefoil factor 1 (pS2/TFF1) and intestinal trefoil factor (ITF)/TFF3, respectively, and corresponded closely with the capacity of the two pathways to stimulate transcription of the genes encoding pS2/TFF1 and ITF/TFF3. We propose a model whereby mucosal wound healing depends solely on activation of STAT1/3, whereas gastric hyperplasia ensues when the coordinated activation of the STAT1/3 and SHP2-Ras-ERK pathways is disrupted.

Expression of trefoil peptides (TFF1, TFF2, and TFF3) in gastric carcinomas, intestinal metaplasia, and non-neoplastic gastric tissues

Trefoil factor family (TFF) domain peptides consist of three members that play a role in intestinal mucosal defence and repair, and in tumourigenesis. The role of the three TFF members in the gastric carcinogenesis cascade remains poorly defined. This study examined seven gastric cell lines, 50 gastric cancers and their adjacent non-cancer tissues, and tissues from 40 non-cancer patients, in order to elucidate the chronology of TFF expression in various stages of gastric carcinogenesis. TFF expression was determined by RT-PCR, immunohistochemistry, and western blot. Aberrant expression of TFF1, TFF2, and TFF3 was frequently detected in gastric cell lines. Specifically, TFF1 was detected in all non-cancer patients, but was detected in only 50% of gastric cancer and 66% of adjacent normal tissues. TFF2 expression was demonstrated in 87.5% of non-cancer patients, 34% of gastric carcinomas, and 58% of adjacent non-cancer tissues. There was a significant correlation between TFF1 and TFF2 expression in gastric cancer and adjacent non-cancer tissues (p<0.001). By contrast, TFF3 was detected in 25% of non-cancer patients and showed a predilection for areas with intestinal metaplasia (p=0.005). Sixty-two per cent of gastric cancers and 24% of neighbouring non-cancer tissues showed TFF3 expression. Immunoreactivity against TFF3 was demonstrated in goblet cells of intestinal metaplasia and within the cytoplasm and nuclei of tumour cells. Progressive loss of TFF1 and TFF2, together with the induction of TFF3, is likely to be involved in the early stage of the multi-step gastric carcinogenesis pathway.