Induction of TFF1 gene expression in pancreas overexpressing transforming growth factor alpha

The Forms of the Lectin Tff2 Differ in the Murine Stomach and Pancreas: Indications for Different Molecular Functions

The lectin TFF2 belongs to the trefoil factor family (TFF). This polypeptide is typically co-secreted with the mucin MUC6 from gastric mucous neck cells, antral gland cells, and duodenal Brunner glands. Here, TFF2 fulfills a protective function by forming a high-molecular-mass complex with the MUC6, physically stabilizing the mucus barrier. In pigs and mice, and slightly in humans, TFF2 is also synthesized in the pancreas. Here, we investigated the murine stomach, pancreas, and duodenum by fast protein liquid chromatography (FPLC) and proteomics and identified different forms of Tff2. In both the stomach and duodenum, the predominant form is a high-molecular-mass complex with Muc6, whereas, in the pancreas, only low-molecular-mass monomeric Tff2 was detectable. We also investigated the expression of Tff2 and other selected genes in the stomach, pancreas, and the proximal, medial, and distal duodenum (RT-PCR analysis). The absence of the Tff2/Muc6 complex in the pancreas is due to a lack of Muc6. Based on its known motogenic, anti-apoptotic, and anti-inflammatory effects, we propose a protective receptor-mediated function of monomeric Tff2 for the pancreatic ductal epithelium. This view is supported by a report that a loss of Tff2 promotes the formation of pancreatic intraductal mucinous neoplasms.

Trefoil Factor Family (TFF) Peptides and Their Links to Inflammation: A Re-evaluation and New Medical Perspectives

Trefoil factor family peptides (TFF1, TFF2, TFF3), together with mucins, are typical exocrine products of mucous epithelia. Here, they act as a gastric tumor suppressor (TFF1) or they play different roles in mucosal innate immune defense (TFF2, TFF3). Minute amounts are also secreted as endocrine, e.g., by the immune and central nervous systems. As a hallmark, TFF peptides have different lectin activities, best characterized for TFF2, but also TFF1. Pathologically, ectopic expression occurs during inflammation and in various tumors. In this review, the role of TFF peptides during inflammation is discussed on two levels. On the one hand, the expression of TFF1-3 is regulated by inflammatory signals in different ways (upstream links). On the other hand, TFF peptides influence inflammatory processes (downstream links). The latter are recognized best in various Tff-deficient mice, which have completely different phenotypes. In particular, TFF2 is secreted by myeloid cells (e.g., macrophages) and lymphocytes (e.g., memory T cells), where it modulates immune reactions triggering inflammation. As a new concept, in addition to lectin-triggered activation, a hypothetical lectin-triggered inhibition of glycosylated transmembrane receptors by TFF peptides is discussed. Thus, TFFs are promising players in the field of glycoimmunology, such as galectins and C-type lectins.

Trefoil Factor Family (TFF) Peptides and Their Diverse Molecular Functions in Mucus Barrier Protection and More: Changing the Paradigm

Trefoil factor family peptides (TFF1, TFF2, TFF3) are typically co-secreted together with mucins. Tff1 represents a gastric tumor suppressor gene in mice. TFFs are also synthesized in minute amounts in the immune and central nervous systems. In mucous epithelia, they support rapid repair by enhancing cell migration ("restitution") via their weak chemotactic and anti-apoptotic effects. For a long time, as a paradigm, this was considered as their major biological function. Within recent years, the formation of disulfide-linked heterodimers was documented for TFF1 and TFF3, e.g., with gastrokine-2 and IgG Fc binding protein (FCGBP). Furthermore, lectin activities were recognized as enabling binding to a lipopolysaccharide of Helicobacter pylori (TFF1, TFF3) or to a carbohydrate moiety of the mucin MUC6 (TFF2). Only recently, gastric TFF1 was demonstrated to occur predominantly in monomeric forms with an unusual free thiol group. Thus, a new picture emerged, pointing to diverse molecular functions for TFFs. Monomeric TFF1 might protect the gastric mucosa as a scavenger for extracellular reactive oxygen/nitrogen species. Whereas, the TFF2/MUC6 complex stabilizes the inner layer of the gastric mucus. In contrast, the TFF3-FCGBP heterodimer (and also TFF1-FCGBP) are likely part of the innate immune defense of mucous epithelia, preventing the infiltration of microorganisms.

The Tumor Suppressor TFF1 Occurs in Different Forms and Interacts with Multiple Partners in the Human Gastric Mucus Barrier: Indications for Diverse Protective Functions

TFF1 is a protective peptide of the Trefoil Factor Family (TFF), which is co-secreted with the mucin MUC5AC, gastrokine 2 (GKN2), and IgG Fc binding protein (FCGBP) from gastric surface mucous cells. Tff1-deficient mice obligatorily develop antropyloric adenoma and about 30% progress to carcinomas, indicating that Tff1 is a tumor suppressor. As a hallmark, TFF1 contains seven cysteine residues with three disulfide bonds stabilizing the conserved TFF domain. Here, we systematically investigated the molecular forms of TFF1 in the human gastric mucosa. TFF1 mainly occurs in an unusual monomeric form, but also as a homodimer. Furthermore, minor amounts of TFF1 form heterodimers with GKN2, FCGBP, and an unknown partner protein, respectively. TFF1 also binds to the mucin MUC6 in vitro, as shown by overlay assays with synthetic ¹²⁵I-labeled TFF1 homodimer. The dominant presence of a monomeric form with a free thiol group at Cys-58 is in agreement with previous studies in Xenopus laevis and mouse. Cys-58 is likely highly reactive due to flanking acid residues (PPEEEC⁵⁸EF) and might act as a scavenger for extracellular reactive oxygen/nitrogen species protecting the gastric mucosa from damage by oxidative stress, e.g., H₂O₂ generated by dual oxidase (DUOX).

Molecular Alterations in the Stomach of Tff1-Deficient Mice: Early Steps in Antral Carcinogenesis

TFF1 is a peptide of the gastric mucosa co-secreted with the mucin MUC5AC. It plays a key role in gastric mucosal protection and repair. Tff1-deficient (Tff1^KO) mice obligatorily develop antropyloric adenoma and about 30% progress to carcinomas. Thus, these mice represent a model for gastric tumorigenesis. Here, we compared the expression of selected genes in Tff1^KO mice and the corresponding wild-type animals (RT-PCR analyses). Furthermore, we systematically investigated the different molecular forms of Tff1 and its heterodimer partner gastrokine-2 (Gkn2) in the stomach (Western blot analyses). As a hallmark, a large portion of murine Tff1 occurs in a monomeric form. This is unexpected because of its odd number of seven cysteine residues. Probably the three conserved acid amino acid residues (EEE) flanking the 7th cysteine residue allow monomeric secretion. As a consequence, the free thiol of monomeric Tff1 could have a protective scavenger function, e.g., for reactive oxygen/nitrogen species. Furthermore, a minor subset of Tff1 forms a disulfide-linked heterodimer with IgG Fc binding protein (Fcgbp). Of special note, in Tff1^KO animals a homodimeric form of Gkn2 was observed. In addition, Tff1^KO animals showed strongly reduced Tff2 transcript and protein levels, which might explain their increased sensitivity to Helicobacter pylori infection.

The TFF Peptides xP1 and xP4 Appear in Distinctive Forms in the Xenopus laevis Gastric Mucosa: Indications for Different Protective Functions

The gastric secretory trefoil factor family (TFF) peptides xP1 and xP4 are the Xenopus laevis orthologs of mammalian TFF1 and TFF2, respectively. The aim of this study was to analyze the molecular forms of xP1 and xP4 in the X. laevis gastric mucosa by FPLC. xP1 mainly occurred in a monomeric low-molecular-mass form and only a minor subset is associated with the mucus fraction. The occurrence of monomeric xP1 is unexpected because of its odd number of cysteine residues. Probably a conserved acidic residue flanking Cys⁵⁵ allows monomeric secretion. Furthermore, Cys⁵⁵ is probably post-translationally modified. For the first time, we hypothesize that the free thiol of monomeric xP1-and probably also its mammalian ortholog TFF1-could have a protective scavenger function, e.g., for reactive oxygen/nitrogen species. In contrast, xP4 mainly occurs in a high-molecular-mass form and is non-covalently bound to a mucin similarly as TFF2. In vitro binding studies with radioactively labeled porcine TFF2 even showed binding to X. laevis gastric mucin. Thus, xP4 is expected to bind as a lectin to an evolutionary conserved sugar epitope of the X. laevis ortholog of mucin MUC6 creating a tight mucus barrier. Taken together, xP1 and xP4 appear to have different gastric protective functions.

Quantitative proteomic analysis of pancreatic cyst fluid proteins associated with malignancy in intraductal papillary mucinous neoplasms

Background

The application of advanced imaging technologies for identifying pancreatic cysts has become widespread. However, accurately differentiating between low-grade dysplasia (LGD), high-grade dysplasia (HGD), and invasive intraductal papillary mucinous neoplasms (IPMNs) remains a diagnostic challenge with current biomarkers, necessitating the development of novel biomarkers that can distinguish IPMN malignancy.

Methods

Cyst fluid samples were collected from nine IPMN patients (3 LGD, 3 HGD, and 3 invasive IPMN) during their pancreatectomies. An integrated proteomics approach that combines filter-aided sample preparation, stage tip-based high-pH fractionation, and high-resolution MS was applied to acquire in-depth proteomic data of pancreatic cyst fluid and discover marker candidates for IPMN malignancy. Biological processes of differentially expressed proteins that are related to pancreatic cysts and aggressive malignancy were analyzed using bioinformatics tools such as gene ontology analysis and Ingenuity pathway analysis. In order to confirm the validity of the marker candidates, 19 cyst fluid samples were analyzed by western blot.

Results

A dataset of 2992 proteins was constructed from pancreatic cyst fluid samples. A subsequent analysis found 2963 identified proteins in individual samples, 2837 of which were quantifiable. Differentially expressed proteins between histological grades of IPMN were associated with pancreatic diseases and malignancy according to ingenuity pathway analysis. Eighteen biomarker candidates that were differentially expressed across IPMN histological grades were discovered—7 DEPs that were upregulated and 11 that were downregulated in more malignant grades. HOOK1 and PTPN6 were validated by western blot in an independent cohort, the results of which were consistent with our proteomic data.

Conclusions

This study demonstrates that novel biomarker candidates for IPMN malignancy can be discovered through proteomic analysis of pancreatic cyst fluid.

Electronic supplementary material

The online version of this article (10.1186/s12014-018-9193-1) contains supplementary material, which is available to authorized users.

Transcriptional Responses in the Murine Spleen after Toxoplasma gondii Infection: Inflammasome and Mucus-Associated Genes

The spleen plays an important role in coordinating both adaptive and innate immune responses. Here, the transcriptional response to T. gondii infection in the murine spleen was characterized concerning inflammasome sensors (two different models: seven days after oral or four weeks after intraperitoneal infection). Additionally, Tff1^KO and Tff3^KO mice were investigated because TFF genes are often upregulated during inflammation. The expression of the pattern-recognition receptors Nlrp3, Nlrp12, and Nlrp1a was significantly increased after infection. This increase was diminished in Tff1^KO and Tff3^KO mice pointing towards a positive regulation of the inflammatory response by Tff1 and Tff3. Furthermore, the transcription of Tff1 (encoding a motogenic lectin) and other secretory genes was analyzed, i.e., gastrokines (Gkn), IgG Fc binding protein (Fcgbp), and the mucin Muc2. The corresponding gene products belong to an interactome protecting mucous epithelia. Tff1 was significantly induced after infection, which might increase the motility of immune cells. In contrast, Gkn3, Fcgbp, and Muc2 were downregulated seven days after oral infection; whereas four weeks after i.p. infection only Gkn3 remained downregulated. This might be an indication that Gkn3, Fcgbp, and Muc2 are involved in the transient disruption of the splenic architecture and its reorganization, which is characteristic after T. gondii infection.

Pancreatic duct glands (PDGs) are a progenitor compartment responsible for pancreatic ductal epithelial repair

Pancreatic duct glands (PDGs) have molecular features known to mark stem cell niches, but their function remains to be determined. To investigate the role of PDGs as a progenitor niche, PDGs were analyzed in both humans and mice. Cells were characterized by immunohistochemistry and microarray analysis. In vivo proliferative activity and migration of PDG cells were evaluated using a BrdU tag-and-chase strategy in a mouse model of pancreatitis. In vitro migration assays were used to determine the role of trefoil factor (TFF) -1 and 2 in cell migration. Proliferative activity in the pancreatic epithelium in response to inflammatory injury is identified principally within the PDG compartment. These proliferating cells then migrate out of the PDG compartment to populate the pancreatic duct. Most of the pancreatic epithelial migration occurs within 5days and relies, in part, on TFF-1 and -2. After migration, PDG cells lose their PDG-specific markers and gain a more mature pancreatic ductal phenotype. Expression analysis of the PDG epithelium reveals enrichment of embryonic and stem cell pathways. These results suggest that PDGs are an epithelial progenitor compartment that gives rise to mature differentiated progeny that migrate to the pancreatic duct. Thus PDGs are a progenitor niche important for pancreatic epithelial regeneration.

Trefoil factor family peptides in normal and diseased human pancreas

OBJECTIVES

Trefoil factor family (TFF) peptides promote wound healing in the gut. Recent evidence has suggested that TFF3 may be a pancreatic mitogen, an unusual role for TFF peptides. We sought to clarify human pancreatic TFF and mucin expression and performed in vitro experiments to see how pancreatic cell lines respond to TFF3 in particular.

METHODS

Samples of normal and diseased pancreas (chronic pancreatitis, pancreatic intraepithelial neoplasia, neuroendocrine tumors, and pancreatic ductal adenocarcinoma [PDAC]) were studied by immunohistochemistry and in situ hybridization. Pancreatic cell lines were challenged with TFF2 and TFF3 in wound and migration assays.

RESULTS

In normal islets, colocalization of insulin or glucagon with TFF3 was common. All TFF messenger RNAs were seen in ductal epithelium. Adenocarcinomas expressed all TFF messenger RNAs. Normal ducts were mucin free; MUC5AC was strongest in pancreatic intraepithelial neoplasia and chronic pancreatitis but was reduced in PDAC. TFF2 induced Panc-1 migration and accelerated wound closure in Capan-2 and COLO-357. Double immunohistochemistry for insulin or TFF3 and Ki67 colabeled only very rare islet cells. TFF3-positive PDAC ducts showed some Ki67 colocalization.

CONCLUSIONS

No correlation between TFF3 or insulin and Ki67 was seen without ductal hyperplasia. TFF2 may assist pancreatic tumor cell movement, but TFF3 may not be a pancreatic mitogen.

Synthesis and localization of trefoil factor family (TFF) peptides in the human urinary tract and TFF2 excretion into the urine

Trefoil factor family (TFF) peptides promote regeneration and repair processes of mucous epithelia. They also probably play a key role in the remarkable regenerative capacity of the urinary tract epithelia. We have localized TFF1, TFF2, and TFF3 expression systematically in surgical specimens from the urinary tract by reverse transcription with the polymerase chain reaction, Western blot analysis, and immunohistochemistry. Urine samples from patients suffering from nephrolithiasis have been investigated and compared with those of healthy controls. TFF synthesis is detectable along the entire urinary tract epithelia. TFF3 synthesis is the most pronounced followed by TFF1, whereas TFF2 synthesis is occasionally detectable but only in trace amounts. In contrast, TFF2 is the predominant TFF peptide excreted into the urine, and significantly increased urinary TFF2 levels (together with occasionally raised TFF3 levels) have been observed in patients suffering from nephrolithiasis. Thus, we consider that TFF3 plays a major part in regeneration and restitution processes in urinary tract epithelia. TFF2 and probably also TFF3 are candidate biomarkers for nephrolithiasis and possibly other inflammatory conditions of the urinary tract.

Airway trefoil factor expression during naphthalene injury and repair

While the role of trefoil factors (TFF) in the maintenance of epithelial integrity in the gastrointestinal tract is well known, their involvement in wound healing in the conducting airway is less well understood. We defined the pattern of expression of TFF1, TFF2, and TFF3 in the airways of mice during repair of both severe (300 mg/kg) and moderate (200 mg/kg) naphthalene-induced Clara cell injury. Quantitative real-time PCR for tff messenger RNA expression and immunohistochemistry for protein expression were applied to airway samples obtained by microdissection of airway trees or to fixed lung tissue from mice at 6 and 24 h and 4 and 7 days after exposure to either naphthalene or an oil (vehicle) control. All three TFF were expressed in normal whole lung and airways. TFF2 was the most abundant and was enriched in airways. Injury of the airway epithelium by 300 mg/kg naphthalene caused a significant induction of tff1 gene expression at 24 h, 4 days, and 7 days. In contrast, tff2 was decreased in the high-dose group at 24 h and 4 days but returned to baseline levels by 7 days. tff3 gene expression was not significantly changed at any time point. Protein localization via immunohistochemistry did not directly correlate with the gene expression measurements. TFF1 and TFF2 expression was most intense in the degenerating Clara cells in the injury target zone at 6 and 24 h. Following the acute injury phase, TFF1 and TFF2 were localized to the luminal apices of repairing epithelial cells and to the adjacent mesenchyme in focal regions that correlated with bifurcations and the bronchoalveolar duct junction. The temporal pattern of increases in TFF1, TFF2, and TFF3 indicate a role in cell death as well as proliferation, migration, and differentiation phases of airway epithelial repair.

Tissue localization of human trefoil factors 1, 2, and 3

Trefoil factors (TTFs) are small, compact proteins coexpressed with mucins in the gastrointestinal tract. Three trefoil factors are known in mammals: TFF1, TFF2, and TFF3. They are implicated to play diverse roles in maintenance and repair of the gastrointestinal channel. We compared the expression pattern of the three trefoil factors analyzing mRNA from a panel of 20 human tissues by conventional reverse transcriptase (RT) PCR and, in addition, by real-time PCR. These findings were supported by immunohistochemical analysis of paraffin-embedded human tissues using rabbit polyclonal antibodies raised against these factors. TFF1 showed highest expression in the stomach and colon, whereas TFF2 and TFF3 showed highest expression in stomach and colon, respectively. All three TFFs were found in the ducts of pancreas. Whereas TFF2 was found to be restricted to these two tissues, the structurally more closely related TFF1 and TFF3 showed a more general tissue distribution and were found to colocalize on an array of mucosal surfaces. This is the first thorough parallel description of the tissue distribution of TFFs in normal tissues, and it provides a baseline for similar analysis in diseased tissues.

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Induced trefoil factor family 1 expression by trans-differentiating Clara cells in a murine asthma model

Asthma is a chronic inflammatory disease of the airways that is accompanied by goblet cell metaplasia and mucus hypersecretion. Trefoil factor family (TFF) peptides represent major secretory products of the respiratory tract and are synthesized together with mucins. In the murine lung, TFF2 is mainly expressed, whereas TFF1 transcripts represent only a minor species. TFF peptides are well known for their motogenic and anti-apoptotic effects, and they modulate the inflammatory response of bronchial epithelial cells. Here, an established mouse model of asthma was investigated (i.e., exposure to Aspergillus fumigatus [AF] antigens). RT-PCR analysis of lung tissue showed elevated levels particularly of TFF1 transcripts in AF-sensitized/challenged animals. In contrast, transcripts encoding Clara cell secretory protein (CCSP/CC10) were strongly diminished in these animals. For comparison, the expression of the goblet cell secretory granule marker mCLCA3/Gob-5, the mucins Muc1-Muc6 and Muc19, and the secretoglobins ScgB3A1 and ScgB3A2, as well as the mammalian ependymin-related gene MERP2, were monitored. Immunohistochemistry localized TFF1 mainly in cells with a mixed phenotype (e.g., TFF1-positive cells stain with the lectin wheat germ agglutinin (WGA), which recognizes mucins characteristic of goblet cells). In addition, these cells express CCSP/CC10, a Clara cell marker. When compared with mucins or CCSP/CC10, TFF1 was stored in a different population of secretory granules localized at the more basolateral portion of these cells. Thus, the results presented indicate for the first time that allergen exposure leads to the trans-differentiation of Clara cells toward a TFF1-expressing mucous phenotype.

Trefoil factor family (TFF) peptides of normal human Vater's ampulla

Vater's ampulla is of great clinical relevance with regard to the influx of chyme, ascending inflammation, intubation during diagnostic and therapeutic endoscopic maneuvers, therapeutic papillotomy and, especially, the formation of malignancies. Little is known about the distribution of trefoil factor family (TFF) peptides in the ampulla. We have therefore examined TFF peptide distribution in the normal ampulla of Vater and compared it with that in duodenal mucosa and Brunner's glands. Expression and synthesis of TFF peptides in Vater's ampulla and duodenum was investigated by reverse transcription-polymerase chain reaction, Western blot and immunohistochemistry. The samples studied originated from 30 autopsy cases with short postmortem intervals. TFF3 was expressed in the ampulla of Vater. mRNA expression of TFF1 was detected in only approximately 25% of the investigated samples. Western blot revealed the production of TFF3 and immunohistochemistry showed that TFF3 was the product of goblet cells. TFF peptide composition of Vater's ampulla varied in comparison with that in the duodenum regarding TFF2 expression. The ampulla of Vater thus has a unique profile of TFF peptide production, supporting the hypothesis that the ampulla is an autonomous organ. The observed differences in the TFF peptide distribution between the duodenum and Vater's ampulla favour the investigation of TFF peptides as prognostic markers in the classification of ampullary carcinomas.

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.

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.

Cell type specific expression of secretory TFF peptides: colocalization with mucins and synthesis in the brain

The "TFF domain" is an ancient cysteine-rich shuffled module forming the basic unit for the family of secretory TFF peptides (formerly P-domain peptides and trefoil factors). It is also an integral component of mosaic proteins associated with mucous surfaces. Three mammalian TFF peptides are known (i.e., TFF1-TFF3); however, in Xenopus laevis the pattern is more complex (xP1, xP4.1, xP4.2, and xP2). TFF peptides are typical secretory products of a variety of mucin-producing epithelial cells (e.g., the conjunctiva, the salivary glands, the gastrointestinal tract, the respiratory tract, and the uterus). Each TFF peptide shows an unique expression pattern and different mucin-producing cells are characterized by their specific TFF peptide/secretory mucin combinations. TFF peptides have a pivotal role in maintaining the surface integrity of mucous epithelia in vivo. They are typical constituents of mucus gels, they modulate rapid mucosal repair ("restitution") by their motogenic and their cell scattering activity, they have antiapoptotic effects, and they probably modulate inflammatory processes. Pathological expression of TFF peptides occurs as a result of chronic inflammatory diseases or certain tumors. TFF peptides are also found in the central nervous system, at least in mammals. In particular, TFF3 is synthesized from oxytocinergic neurons of the hypothalamus and is released from the posterior pituitary into the bloodstream.

Reduced PTEN expression in the pancreas overexpressing transforming growth factor-beta 1

PTEN is a candidate tumour suppressor gene and frequently mutated in multiple cancers, however, not in pancreatic cancer. Recently, it has been demonstrated that PTEN expression is regulated by TGF-beta1. Using TGF-beta1 transgenic mice (n=7) and wildtype littermates (n=6), as well as pancreatic tissues obtained from organ donors (n=10) and patients with pancreatic cancer (n=10), we assessed the expression of PTEN by means of immunohistochemistry and semiquantitative PCR analysis. In addition, PANC-1 cells were treated with TGF-beta1 in vitro and the levels of PTEN mRNA were determined in these cells. In human pancreatic cancers PTEN mRNA levels were significantly decreased (P<0.05). In addition, in the pancreas of TGF-beta1 transgenic mice the expression of PTEN was significantly reduced (P<0.01), as compared to wildtype littermates and incubation of PANC-1 cells with TGF-beta1 decreased PTEN mRNA levels after 24 h. Inasmuch as TGF-beta1 decreases PTEN expression in human pancreatic cancer cells and human pancreatic cancers overexpress TGF-beta1, the reduced expression of PTEN in pancreatic cancer may be mediated by TGF-beta1 overexpression. Thus, although PTEN is not mutated in pancreatic cancers, the reduction of its expression may give pancreatic cancer cells an additional growth advantage.

High expression of the trefoil protein TFF1 in interval breast cancers

Breast cancer screening is important for the early detection of breast cancer. Tumors that become symptomatic in the screening interval are known as interval cancers but the reasons for their rapid progression are unknown. Estrogen receptor expression is lower in interval cancers suggesting that they may have reduced hormonal responsiveness. To investigate this hypothesis we have measured the expression of the estrogen receptor and three estrogen-responsive genes (cathepsin D, progesterone receptor, and TFF1) in screen-detected and interval breast cancers. The expression of the protease cathepsin D was not associated with estrogen receptor in either group of tumor. Progesterone receptor expression was highly correlated with that of the estrogen receptor in both groups of tumors but it was not expressed at significantly different levels in the two groups of tumors. Expression of TFF1, a cellular motogen, was correlated with estrogen receptor in screen-detected but not interval cancers and was expressed at markedly higher levels in interval breast tumors, the group that expresses lower levels of estrogen receptor. Interval cancers are characterized by high levels of expression of TFF1 and/or Ki67 suggesting that cell migration and cell division play important roles in the rapid progression of interval cancers. The observation that TFF1 expression in interval cancers tends to be estrogen-independent and that interval cancers have reduced estrogen receptor expression suggests they may have a reduced response to hormone therapy.

Spatio-temporal expression of trefoil peptide following severe gastric ulceration in the rat implicates it in late-stage repair processes

BACKGROUND

The trefoil peptide (TFF1) is a member of a family of mucin-associated regulatory peptides that are widely distributed in gastrointestinal tissues and have been implicated in the maintenance of the gastric mucosa. The role of TFF1 in gastric mucosal repair was examined by analysis of the spatio-temporal expression of TFF1 following gastric ulceration in the rat.

METHODS

Gastric ulcers were induced in rats by application of glacial acetic acid to the serosa of the fundus. At various time points post injury (0-28 days), macroscopic and microscopic examination of the gastric mucosa was performed. In addition, the spatio-temporal expression of TFF1 protein and proliferating cell nuclear antigen were identified by immunohistochemistry, TFF1 message by in situ hybridization, and acidic/neutral secreting mucins by Alcian blue-periodic acid-Schiff staining.

RESULTS

In normal rat gastric tissue, TFF1 peptide and mRNA were expressed in mucosal cells of the superficial epithelium. Trefoil peptide and mRNA were significantly induced between 4 and 28 days post ulceration, with expression extending beyond the superficial epithelium and being localized to acidic mucin-producing cells deep within the repairing mucosa.

CONCLUSIONS

Spatio-temporal expression of TFF1 mRNA and peptide following macroscopic repair implicates TFF1 as a potential mediator of late stage-repair processes. Whether this is through direct stimulation of cellular differentiation or the enhancement of mucosal protective properties through an interaction with gastric mucins remains to be elucidated.

Characterization of the mouse TFF1 (pS2) gene promoter region

Trefoil peptides (TFFs) with a unique trefoil domain(s) are presumed to function in protection and repair of the gastrointestinal epithelial layer. Three peptide family members are differently distributed in the mouse gastrointestinal tract: TFF1/pS2 specifically in stomach, TFF2/SP mainly in stomach, pancreas and duodenum, and TFF3/ITF in intestine. We cloned and sequenced the mouse TFF1 gene 5'-upstream region by means of the genomic walking procedure. The cloned region was ligated to the luciferase reporter gene and then introduced into mouse gastric surface mucous GSM10 cells which express TFF1 and TFF2. The minimum promoter was located in the region containing the TATA-box between -39 and the transcriptional start site. Further upstream regions stimulated (-2192-- -1630bp, -641-- -243bp, -137-- -39bp) and inhibited (-1630-- -641bp, -243-- -137 bp) luciferase gene expression. These regions as well as short segments conserved in the mouse and human 5'-upstream sequences may be important for modulation of the mRNA level of the TFF1 gene.

Loss of TGF-beta signaling contributes to autoimmune pancreatitis

Recent observations suggest that immune response is involved in the development of pancreatitis. However, the exact pathogenesis underlying this immune-mediated response is still under debate. TGF-beta has been known to be an important regulating factor in maintaining immune homeostasis. To determine the role of TGF-beta in the initiation or progression of pancreatitis, TGF-beta signaling was inactivated in mouse pancreata by overexpressing a dominant-negative mutant form of TGF-beta type II receptor in the pancreas, under control of the pS2 mouse trefoil peptide promoter. Transgenic mice showed marked increases in MHC class II molecules and matrix metalloproteinase expression in pancreatic acinar cells. These mice also showed increased susceptibility to cerulein-induced pancreatitis. This pancreatitis was characterized by severe pancreatic edema, inflammatory cell infiltration, T- and B-cell hyperactivation, IgG-type autoantibodies against pancreatic acinar cells, and IgM-type autoantibodies against pancreatic ductal epithelial cells. Therefore, TGF-beta signaling seems to be essential either in maintaining the normal immune homeostasis and suppressing autoimmunity or in preserving the integrity of pancreatic acinar cells.