Epigenetic Regulation of CD133 in Gastrointestinal Stromal Tumors.

OBJECTIVES: This study ascertained the regulation of the stem cell marker CD133 and its potential applicability for prognostication of gastrointestinal stromal tumors (GISTs). METHODS: A total of 95 resected GISTs were included in the study. CD133 protein expression was assessed immunohistochemically on tissue microarrays. Methylation percentage was quantified by pyrosequencing. Gene expression in cell lines GIST48b and GIST882 upon treatment with DNA demethylation agent 5-aza-2'-deoxycytidine was analyzed by quantitative polymerase chain reaction. RESULTS: The expression of hypermethylated CD133 could be reactivated in the GIST cell line upon hypomethylation with the drug. Similarly, in patient material, CD133 methylation percentage correlated inversely with the protein expression and reflected tumor size with hypermethylation in small (<2 cm) tumors and virtually no methylation in large (>10 cm) GISTs. The gene's methylation percentage and expression level were clearly specific to anatomic sites and distinct driver mutations. KIT -mutant gastric GISTs exhibited significantly lower methylation degrees and concomitant high CD133 protein abundance compared with KIT -mutant GISTs from the small intestine. CD133 hypermethylation was documented in PDGFRA -mutant gastric GISTs along with low CD133 expression compared with KIT -mutant gastric GISTs. High CD133 expression was a prognosticator of shorter disease-free survival in all patients. In a subgroup of KIT -mutant gastric GISTs, low CD133 methylation degree was correlated with a shorter disease-free survival. CONCLUSIONS: Our results strongly suggest epigenetic regulation of CD133 expression by promoter methylation in GISTs. Pending further validation studies, high abundance of the protein can serve as a marker for malignant GISTs.

Molecular analysis of BRAF V600E mutation in multiple nodules of pulmonary Langerhans cell histiocytosis.

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare, smoking-related histiocytic disorder with variable clinical symptoms. Like in other non-pulmonary Langerhans cell proliferations, PLCH has recently been shown to harbour BRAF V600E mutations in a significant subset of cases, thus challenging the concept of PLCH being a reactive disorder. Here, we analysed 38 formalin-fixed and paraffin-embedded PLCH nodules of nine patients for BRAF mutation using two different molecular methods. Using pyrosequencing and allele-specific quantitative PCR (AS-PCR), BRAF V600E mutations were found in 16/38 (42%) and 31/37 (84%) nodules, respectively. Analysing different nodules of the same patients with pyrosequencing 3/6 patients showed a concordant BRAF mutation status. When allele-specific quantitative PCR was used, condordant results were found in 5/6 patients. Our findings clearly indicate that (a) the sensitivity of the method used is crucial in analysing BRAF mutation status, (b) AS-PCR is more sensitive in detecting BRAF V600E mutations than pyrosequencing,

Pattern of TGFbeta receptor 1 expression differs between kras-mutated keratoacanthomas and squamous cell carcinomas of the skin.

PURPOSE: Increasing evidence indicates that TGFbeta- and EGFR-signaling is involved in the pathogenesis of keratoacanthoma (KA) and squamous cell carcinoma (SCC) of the skin. We analyzed the expression pattern of TGFbeta-signaling components and screened for mutations in tgfbetaR1, egfr, kras and braf in KAs and SCCs. METHODS: Immunohistochemical analysis of TGFbeta1, TGFbetaR1, TGFbetaR2 and phospho-SMAD2/3 was performed on skin tumors (29 KAs, 30 well and 31 moderately differentiated SCCs). Mutation screening in hotspot regions of tgfbetaR1, egfr, kras and braf was performed through pyrosequencing of tumor DNA. FINDINGS: Expression of TGFbeta1, TGFbetaR1 and p-SMAD2/3 was increased in tumors as compared to surrounding skin. In KAs characteristic strong discontinuous membranous TGFbetaR1 expression pattern frequently associated with kras mutation was noted. SCCs showed continuous TGFbetaR1 expression, stronger p-SMAD2/3 expression and less frequent kras mutations. In tumors at sun-exposed sites stronger TGFbetaR1 expression was noted. One SCC showed tgfbetaR1 mutation, but no other mutations were found. CONCLUSION: Although tgfbetaR1 germline mutations cause inherited KAs and our finding of strong discontinuous membranous expression in KAs suggests accumulation of functionally altered protein, we found no tgfbetaR1 mutations or influence on TGFbeta-signaling, but frequent kras mutations in this subgroup of KAs. Characteristic TGFbetaR1 expression pattern in KA can facilitate histopathologic distinction from SCC.

EGFR, KRAS, BRAF-mutations and microsatellite instability are absent in goblet cell carcinoids of the appendix.

Goblet cell carcinoid (GCC) is a rare type of mixed endocrine-exocrine tumor of the appendix often showing a clinically aggressive behavior. On a molecular basis, this tumor is only poorly understood. To analyze possible molecular similarities between GCC and colorectal cancer, we examined 14 cases of GCC for mutations in exons 18, 19 and 21 of the EGFR-gene, exon 2 in the KRAS gene and for V600E mutations of the BRAF gene. Although the sensitive pyrosequencing method was used, no EGFR, KRAS or BRAF mutations could be found. Furthermore, using immunohistochemistry, no evidence for microsatellite instabillity (MSI) could be found. Despite the partial intestinal differentiation of GCC, our study indicates that the molecular pathogenesis of GCC significantly differs from conventional colorectal adenocarcinoma. This finding might also have implications in adjuvant chemotherapeutic treatment of advanced GCC.

EGFR, HER2 and HER3 dimerization patterns guide targeted inhibition in two histotypes of esophageal cancer.

Receptor tyrosine kinases (RTKs) are in the focus of targeted therapy for epithelial tumors. Our study addressed the role of EGFR, HER2 and HER3 expression and dimerization in esophageal cancers in situ and in vitro in the context of therapeutic EGFR and HER2 inhibitors. In archival pretreatment biopsies of esophageal carcinomas (n = 110), EGFR was preferentially expressed in esophageal squamous cell carcinomas (ESCCs) (22.4%; p = 0.088) and HER2 (34.4%; p < 0.001) with HER3 (91.5%; p < 0.001) in esophageal (Barrett's) adenocarcinomas (EACs). In situ proximity ligation assays revealed mainly EGFR and HER2 homodimers in ESCC and EAC cases, respectively. However, EAC cases also exhibited HER2/HER3 heterodimers. In vitro ESCC (OE21) cells displayed a significant response to erlotinib, gefitinib and lapatinib, with loss of AKT phosphorylation, G0/G1 cell cycle arrest and induction of apoptosis. In EAC cells (OE19, OE33 and SK-GT-4), lapatinib was similarly effective in strongly HER2-positive (mainly HER2 homodimers and some HER2/EGFR heterodimers) OE19 and OE33 cells. The HER2-targeting antibodies (trastuzumab and pertuzumab) given alone were largely ineffective in ESCC and EAC cells. However, both antibodies significantly induced antibody-dependent cellular cytotoxicity in EAC (OE19 and OE33) cells upon co-culture with peripheral blood mononuclear cells. The study reveals that overexpression of EGFR and HER2 predominantly results in homodimers in ESCCs and EACs, respectively. Still, some EACs also show HER2 dimerization plasticity, e.g., with HER3. Such RTK dimerization patterns affect responses to EGFR and HER2 targeting inhibitors in ESCC and EAC cells in vitro and hence may influence future prediction for particularly HER2-targeting inhibitors in EACs.

Effects of polysaccharide isolated from Streptococcus thermophilus CRL1190 on human gastric epithelial cells.

EPS1190 was isolated from skim milk fermented with Stretococcus thermophilus CRL1190. The polysaccharide consisted of 33% glucose and 66% galactose with 1,4- and 1,4,6-galactose residues as main building blocks beside a high amount of 1,4-linked glucose. The polymer was characterized additionally concerning viscosity and zeta potential. EPS1190 stimulated cellular vitality and proliferation of human stomach AGS cells and human buccal KB cells significantly. EPS1190 stimulated phagocytosis rate of murine macrophages RAW264.7 significantly. NO-release or anti-inflammatory effects by inhibition of LPS-induced NO release were not observed. Confocal laser scanning microscopy revealed that EPS1190 is partially internalized into AGS cells via endosomes. The bioadhesive absorption of FITC-labeled EPS1190 into the mucus layer on the apical side of the epithelium using histological tissue sections from human stomach was observed. Specific interaction of EPS1190 with mucin can be excluded as shown by microviscosimetry studies. EPS1190 increased the adhesion of H. pylori to AGS cells, which resulted in increased secretion of proinflammatory cytokines TNFa, IL-6 and IL-8. Summarizing, EPS1190 seems to stimulate epithelial cell regeneration and immunological innate defense mechanisms, which again can rationalized the use of this polysaccharide as cytoprotective compound in probiotioc preparations.

Methylation-dependent activation of CDX1 through NF-κB: a link from inflammation to intestinal metaplasia in the human stomach.

The caudal homeobox factor 1 (CDX1) is an essential transcription factor for intestinal differentiation. Its aberrant expression in intestinal metaplasia of the upper gastrointestinal tract is a hallmark within the gastritis-metaplasia-carcinoma sequence. CDX1 expression is influenced by certain pathways, such as Wnt, Ras, or NF-κB signaling; however, these pathways alone cannot explain the transient expression of CDX1 in intestinal metaplasia or the molecular inactivation mechanism of its loss in cases of advanced gastric cancer. In this study, we investigated the epigenetic inactivation of CDX1 by promoter methylation, as well as the functional link of CDX1 promoter methylation to the inflammatory NF-κB signaling pathway. We identified methylation-dependent NF-κB binding to the CDX1 promoter and quantified it using competitive electrophoretic mobility shift assays and chromatin immunoprecipitation. A methylated CDX1 promoter was associated with closed chromatin structure, reduced NF-κB binding, and transcriptional silencing. Along the gastritis-metaplasia-carcinoma sequence, we observed a biphasic pattern of tumor necrosis factor-α (TNF-α) protein expression and an inverse biphasic pattern of CDX1 promoter methylation; both are highly consistent with CDX1 protein expression. The stages of hyper-, hypo-, and hyper-methylation patterns of the CDX1 promoter were inversely correlated with the NF-κB signaling activity along this sequence. In conclusion, these functionally interacting events drive CDX1 expression and contribute to intestinal metaplasia, epithelial dedifferentiation, and carcinogenesis in the human stomach.

The ZEB1/miR-200 feedback loop controls Notch signalling in cancer cells.

Notch signalling is important for development and tissue homeostasis and activated in many human cancers. Nevertheless, mutations in Notch pathway components are rare in solid tumours. ZEB1 is an activator of an epithelial-mesenchymal transition (EMT) and has crucial roles in tumour progression towards metastasis. ZEB1 and miR-200 family members repress expression of each other in a reciprocal feedback loop. Since miR-200 members target stem cell factors, ZEB1 indirectly induces stemness maintenance and associated drug resistance. Here, we link ZEB1 and its cancer promoting properties to Notch activation. We show that miR-200 members target Notch pathway components, such as Jagged1 (Jag1) and the mastermind-like coactivators Maml2 and Maml3, thereby mediating enhanced Notch activation by ZEB1. We further detected a coordinated upregulation of Jag1 and ZEB1, associated with reduced miR-200 expression in two aggressive types of human cancer, pancreatic adenocarcinoma and basal type of breast cancer. These findings explain increased Notch signalling in some types of cancers, where mutations in Notch pathway genes are rare. Moreover, they indicate an additional way how ZEB1 exerts its tumour progressing functions.

Aqueous extracts and polysaccharides from liquorice roots (Glycyrrhiza glabra L.) inhibit adhesion of Helicobacter pylori to human gastric mucosa.

AIMS: Aqueous extracts from the roots of Glycyrrhiza glabra L. (Fabaceae) are widely used for treatment of stomach ulcer. The clinical proven effects are related to the presence of anti-inflammatory 12-keto-triterpensaponins in the extracts. Apart from that the influence of Glycyrrhiza glabra extract on the bacterial adhesion of Helicobacter pylori to stomach tissue was to be investigated. Additionally the influence of Glycyrrhiza glabra secondary compounds on the bacterial adhesion of Porphyromonas gingivalis, a major pathogen for induction of periodontal inflammations was to be investigated. METHODOLOGY: In vitro cytotoxicity against Helicobacter pylori was investigated by agar diffusion assay; antiadhesive properties of aqueous extract, raw polysaccharides and purified polysaccharide fractions was investigated by means of an in situ adhesion assay with FITC-labelled bacteria on tissue slides of human stomach resectates. RESULTS: Aqueous extract (1mg/mL) of Glycyrrhiza glabra significantly inhibited the adhesion of Helicobacter pylori to human stomach tissue. This effect was related to the polysaccharides isolated from the extract, with one purified acidic fraction (0.25 SPB) as main active polymer. Purified polysaccharides did not exhibit direct cytotoxic effects against Helicobacter pylori and did not influence hemagglutination. Additionally raw polysaccharides from Glycyrrhiza glabra were shown to have strong antiadhesive effects against Porphyromonas gingivalis. CONCLUSION: Aqueous extracts and polysaccharides from the roots of Glycyrrhiza glabra are strong antiadhesive systems, which may be used as potent tools for a further development of cytoprotective preparations with anti-infectious potential.

Evaluation of sensitivity and inter- and intra-observer variability in the detection of intestinal metaplasia and dysplasia in Barrett's esophagus with enhanced magnification endoscopy.

OBJECTIVE: Magnification endoscopy with acetic acid or dye for diagnosis of Barrett's esophagus is presently undergoing clinical evaluation. Current studies report good accuracy in predicting specialized intestinal metaplasia. To date, however, there is no definitive information on the inter- and intra-observer variability of these methods applied to the diagnosis of normal and dysplastic Barrett's mucosa. MATERIAL AND METHODS: Sixty patients with endoscopically suspected Barrett's esophagus were investigated prospectively with the zoom endoscope after contrast enhancement of the mucosa with 1.5% acetic acid. Two hundred and twenty-three enlarged and histologically investigated areas of gastric, cardiac, normal and dysplastic Barrett's mucosa were photodocumented and in randomized sequence presented to 4 endoscopists in a blinded manner (2 with and 2 without experience of zoom endoscopy for evaluation). The reference for the first evaluation (A1) was standard endoscopic photographs of the respective, histologically confirmed mucosal entity. In a second evaluation (A2), the pictures were again interpreted by the same blinded investigators, but this time a modified pit-pattern classification as proposed by Sharma et al. was employed as the evaluation reference. RESULTS: The diagnostic sensitivity for specialized intestinal metaplasia and dysplasia in Barrett's esophagus calculated for the A1 evaluation ranged -- investigator dependently -- from 54.9% to 80.7% and for A2 from 42.2% to 81.5%. The inter- and intra-observer variability for the evaluation procedure A1 and A2 was high (all kappa values <0.4). In particular, the inexperienced investigators demonstrated high intra-observer variability and low sensitivity in comparison with the experienced investigators. CONCLUSIONS: The diagnosis of Barrett's mucosa using enhanced magnification endoscopy after acetic acid instillation is associated with a high level of interobserver variability. One reason is a frequent mismatch between cardiac mucosa and non-dysplastic Barrett's mucosa.

Aberrant expression of TTF-1 and forkhead factor HFH-4 in atrophic gastritis and ciliated metaplasia suggests gastric broncho-pulmonary transdetermination.

Ciliated metaplasia (CM) in the stomach is mainly found in gastric mucosa that harbours gastric cancer. The true nature of this lesion and the regulatory factors responsible for the formation of CM are unknown. Broncho-pulmonary differentiation is controlled by the homeodomain transcription factor TTF-1 and ciliogenesis by the forkhead transcription factor HFH-4, respectively. Using immunohistochemistry, the present study shows that gastric CM is associated with the expression of TTF-1 and HFH-4. Furthermore, TTF-1 expression was found in non-ciliated cells in 50% of cases with atrophic gastritis, whereas TTF-1 and HFH-4 were not expressed in normal gastric mucosa or in non-atrophic gastritis. These data suggest that CM in the gastric mucosa can be regarded as gastric broncho-pulmonary transdetermination. Evidence for this particular transdetermination is frequently found in atrophic gastritis even without fully developed ciliated cells.

Inverse correlation of maturity and antibacterial activity in human dendritic cells.

Dendritic cells (DCs) are a key part of host defense against microbial pathogens, being part of the innate immune system, but also instructing the adaptive T cell response. This study was designed to evaluate whether human DCs directly contribute to innate immunity by killing intracellular bacteria, using tuberculosis as a model. DCs were detected in bronchoalveolar lavage samples indicating that DCs are available for immediate interaction with Mycobacterium tuberculosis (M. Tb) after inhalation of the pathogen. The phenotype of DC in bronchoalveolar lavage closely resembles monocyte-derived immature DC (iDC) according to the expression of CD1a, CD83, and CCR7. The antimicrobial activity of iDC against intracellular M. Tb inversely correlated with TNF-alpha-release and was enhanced by treatment with anti-TNF-alpha Abs. Differentiation of iDC into mature DC by addition of TNF-alpha or activation via Toll-like receptors further reduced killing of M. Tb. The antibacterial activity against intracellular M. Tb of all DCs was significantly lower than alveolar macrophages. Therefore, the maintenance of a pool of DCs at the site of disease activity in tuberculosis, and the maturation of these DC by TNF-alpha provides a mechanism by which M. Tb escapes the innate immune system.

Immunological and morphogenic basis of gastric mucosa atrophy and metaplasia.

Chronic gastritis with gastric mucosa atrophy, intestinal metaplasia and endocrine cell hyperplasia are alterations with an increased risk for the development of gastric neoplasias. Immunological studies in autoimmune gastritis, in atrophic Helicobacter pylori gastritis and in studies with transgenic mice point to a central role of the parietal cell in the development of gastric mucosa atrophy. Destruction of gastric epithelial cells alone might not be sufficient for the loss of complete gastric glands. Gastric atrophy, endocrine cell hyperplasia and intestinal and pancreatic metaplasia can be regarded as the result of altered morphogenesis within the gastric mucosa. Impaired expression of the gastric morphogenic factor Sonic Hedgehog by parietal cells and increased expression of the transcriptional activators of intestinal and pancreatic differentiation, namely CDX2 and PDX1, seem to be crucial for the development of gastric atrophy and for intestinal, endocrine and pancreatic transdifferentiation processes. Altered expression of these morphogenic factors is partly caused by changes in the gastric milieu. Further studies concerning the normal and pathological morphogenesis of the gastric mucosa and related tissues might give new insight into the pathogenesis of gastric atrophy and metaplasia.

Down-regulation of the homeodomain factor Cdx2 in colorectal cancer by collagen type I: an active role for the tumor environment in malignant tumor progression.

The homeobox transcription factor Cdx2 specifies intestinal development and homeostasis and is considered a tumor suppressor in colorectal carcinogenesis. However, Cdx2 mutations are rarely found. Invasion of colorectal cancer is characterized by a transient loss of differentiation and nuclear accumulation of the oncoprotein beta-catenin in budding tumor cells. Strikingly, this is reversed in growing metastases, indicating that tumor progression is a dynamic process that is not only driven by genetic alterations but also regulated by the tumor environment. Here we describe a transient loss of Cdx2 in budding tumor cells at the tumor host interface, and reexpression of Cdx2 in metastases. Cell culture experiments show that collagen type I, through beta(1) integrin signaling, triggers a transient transcriptional down-regulation of Cdx2 and its intestine-specific target gene sucrase isomaltase, associated with a loss of differentiation. These data indicate an active role for the tumor environment in malignant tumor progression.

Evidence for acid-induced loss of Cdx2 expression in duodenal gastric metaplasia.

Gastric metaplasia in the duodenum (GMD) is characterized by transdifferentiation of intestinal epithelial cells into gastric foveolar cells within the duodenal mucosa. GMD is often associated with duodenal ulceration. Higher duodenal acidity due to increased gastric acid output into the duodenum has been implicated in the development of GMD. Intestinal development and homeostasis are controlled by the homeobox transcription factor Cdx2, which is considered to be the master regulator of intestinal differentiation. Using immunohistochemistry, the present study shows that GMD is associated with loss of expression of Cdx2 and its target gene product sucrase-isomaltase. Quantitative RT-PCR experiments using the intestinal cell line Caco2 revealed that Cdx2 and sucrase-isomaltase were down-regulated and gastric mucins MUC5AC and MUC6 were up-regulated under acidic culture conditions. Thus, it is suggested that increased acid exposure leads to GMD by impairing the transcription of Cdx2 and subsequently that of its intestine-specific target genes.

Helicobacter pylori associated antigastric autoantibodies: role in Sjögren's syndrome gastritis.

BACKGROUND: Previous studies have shown that Helicobacter pylori seroprevalence in Sjögren's syndrome is comparable with that of the general population. However, the origin of the chronic gastropathy associated with this syndrome and the role of local autoimmunity--possibly triggered by bacterial infection--in its pathogenesis remain unclear. MATERIALS AND METHODS: We initially determined the prevalence of IgG anti H. pylori in dyspeptic subjects with and without Sjögren's syndrome. In subsets of both groups we then determined anti CagA and human tissue-tested anticanalicular/antifoveolar autoantibodies. We also compared activity, atrophy and Mucosa Associated Lymphoid Tissue (MALT) scores, as well as symptoms, before and after bacterial eradication. RESULTS: Prevalence of H. pylori in Sjögren's syndrome patients was similar to controls: 31/54 (57%) vs. 93/150 (62%). Anti CagA prevalence was also similar in the two groups. Twenty weeks after H. pylori eradication, histological activity decreased in both groups, however, atrophy and MALT decreased significantly only in controls. Sixteen months after H. pylori eradication, 75% of Sjögren's syndrome patients still complained of dyspepsia compared with 13% of controls. Finally, antigastric autoantibodies were present in 29% of tested Sjögren's syndrome patients vs. 28% of controls. CONCLUSIONS: H. pylori infection was equally prevalent among dyspeptic Sjögren's syndrome patients and dyspeptic controls. Likewise, there were no differences regarding anti CagA prevalence or antigastric autoantibodies among the two groups. The persistence of symptoms as well as of the lymphocytic infiltration and atrophy after H. pylori eradication in Sjögren's syndrome may underlie the 'endogenous' and still unknown nature of the gastropathy in this condition.

Glycosylated compounds from okra inhibit adhesion of Helicobacter pylori to human gastric mucosa.

In Asian medicine the fruit of the okra plant, Abelmoschus esculentus (L.) Moench., is used as a mucilaginous food additive against gastric irritative and inflammative diseases. To find a rational basis for its use against these diseases, several crude and purified carbohydrate-containing fractions from immature okra fruits were isolated and analyzed, and their effects against Helicobacter pylori in an in situ adhesion model on sections of human gastric mucosa were determined. Pretreatment of the bacteria with a fresh juice preparation inhibited the bacterial adhesion almost completely. Lyophilization and reconstitution of an extract solution led to a reduction of this effect. A crude polysaccharide (RPS) isolated from the fresh juice by ethanolic precipitation showed strong inhibitory effects. Further fractionation of RPS revealed a purified, highly acidic subfraction (AF III) with high antiadhesive qualities. Carbohydrate analysis revealed the presence of rhamnogalacturonans with a considerable amount of glucuronic acid, whereas other inactive subfractions contained little glucuronic acid or were glucuronic acid-free. After heat denaturation of the fresh juice or protein precipitation with 5% TCA the antiadhesive activity of the fresh extract was reduced, indicating that besides polysaccharides, protein fractions also exhibited antiadhesive properties. SDS-PAGE analysis of the precipitate revealed several bands of glycosylated proteins between 25 and 37 kDa that were almost diminished in the nonactive supernatant. Preincubations of gastric tissue with any of the active fractions did not lead to reduced bacterial binding. The antiadhesive activity is therefore due to the blocking capacity of specific Helicobacter surface receptors that coordinate the interaction between host and bacterium. Neither of the active fractions showed inhibitory effects on bacterial growth in vitro. The antiadhesive qualities of okra were assumed to be due to a combination of glycoproteins and highly acidic sugar compounds making up a complex three-dimensional structure that is fully developed only in the fresh juice of the fruit.