Molecular and cellular analysis of rP1.B in the rat hypothalamus: in situ hybridization and immunohistochemistry of a new P-domain neuropeptide

Expression Profiling along the Murine Intestine: Different Mucosal Protection Systems and Alterations in Tff1-Deficient Animals

Tff1 is a typical gastric peptide secreted together with the mucin, Muc5ac. Tff1-deficient (Tff1KO) mice are well known for their prominent gastric phenotype and represent a recognized model for antral tumorigenesis. Notably, intestinal abnormalities have also been reported in the past in these animals. Here, we have compared the expression of selected genes in Tff1KO mice and their corresponding wild-type littermates (RT-PCR analyses), focusing on different mucosal protection systems along the murine intestine. As hallmarks, genes were identified with maximum expression in the proximal colon and/or the duodenum: Agr2, Muc6/A4gnt/Tff2, Tff1, Fut2, Gkn2, Gkn3, Duox2/Lpo, Nox1. This is indicative of different protection systems such as Tff2/Muc6, Tff1-Fcgbp, gastrokines, fucosylation, and reactive oxygen species (ROS) in the proximal colon and/or duodenum. Few significant transcriptional changes were observed in the intestine of Tff1KO mice when compared with wild-type littermates, Clca1 (Gob5), Gkn1, Gkn2, Nox1, Tff2. We also analyzed the expression of Tff1, Tff2, and Tff3 in the pancreas, liver, and lung of Tff1KO and wild-type animals, indicating a cross-regulation of Tff gene expression. Furthermore, on the protein level, heteromeric Tff1-Fcgbp and various monomeric Tff1 forms were identified in the duodenum and a high-molecular-mass Tff2/Muc6 complex was identified in the proximal colon (FPLC, proteomics).

Different Molecular Forms of TFF3 in the Human Respiratory Tract: Heterodimerization with IgG Fc Binding Protein (FCGBP) and Proteolytic Cleavage in Bronchial Secretions

The polypeptide TFF3 belongs to the trefoil factor family (TFF) of lectins. TFF3 is typically secreted from mucous epithelia together with mucins. Both intestinal and salivary TFF3 mainly exist as disulfide-linked heterodimers with IgG Fc binding protein (FCGBP). Here, we investigated bronchial tissue specimens, bronchial secretions, and bronchoalveolar lavage (BAL) fluid from patients with a chronic obstructive pulmonary disease (COPD) background by fast protein liquid chromatography and proteomics. For the first time, we identified different molecular forms of TFF3 in the lung. The high-molecular mass form represents TFF3-FCGBP oligomers, whereas the low-molecular mass forms are homodimeric and monomeric TFF3 with possibly anti-apoptotic activities. In addition, disulfide-linked TFF3 heterodimers with an M_r of about 60k and 30k were detected in both bronchial secretions and BAL fluid. In these liquids, TFF3 is partly N-terminally truncated probably by neutrophil elastase cleavage. TFF3-FCGBP is likely involved in the mucosal innate immune defense against microbial infections. We discuss a hypothetical model how TFF3 might control FCGBP oligomerization. Furthermore, we did not find indications for interactions of TFF3-FCGBP with DMBT1gp³⁴⁰ or the mucin MUC5AC, glycoproteins involved in mucosal innate immunity. Surprisingly, bronchial MUC5AC appeared to be degraded when compared with gastric MUC5AC.

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 3 (TFF3) Is Involved in Cell Migration for Skeletal Repair

The aim of the study was to explore the possible role of Trefoil Factor Family peptide 3 (TFF3) for skeletal repair. The expression of TFF3 was analyzed in human joint tissues as well as in a murine bone fracture model. Serum levels of TFF3 following a defined skeletal trauma in humans were determined by ELISA. The mRNA expression of TFF3 was analyzed under normoxia and hypoxia. Expression analysis after stimulation of human mesenchymal progenitor cells (MPCs) with TFF3 was performed by RT² Profiler PCR Array. The effect of recombinant human (rh)TFF3 on MPCs was analysed by different migration and chemotaxis assays. The effect on cell motility was also visualized by fluorescence staining of F-Actin. TFF3 was absent in human articular cartilage, but strongly expressed in the subchondral bone and periosteum of adult joints. Strong TFF3 immunoreactivity was also detected in murine fracture callus. Serum levels of TFF3 were significantly increased after skeletal trauma in humans. Expression analysis demonstrated that rhTFF3 significantly decreased mRNA of ROCK1. Wound healing assays showed increased cell migration of MPCs by rhTFF3. The F-Actin cytoskeleton was markedly influenced by rhTFF3. Cell proliferation was not increased by rhTFF3. The data demonstrate elevated expression of TFF3 after skeletal trauma. The stimulatory effects on cell motility and migration of MPCs suggest a role of TFF3 in skeletal repair.

Trefoil factor family peptides – friends or foes?

Trefoil factor family (TFF) peptides are a group of molecules bearing a characteristic three-loop trefoil domain. They are mainly secreted in mucous epithelia together with mucins but are also synthesized in the nervous system. For many years, TFF peptides were only known for their wound healing and protective function, e.g. in epithelial protection and restitution. However, experimental evidence has emerged supporting a pivotal role of TFF peptides in oncogenic transformation, tumorigenesis and metastasis. Deregulated expression of TFF peptides at the gene and protein level is obviously implicated in numerous cancers, and opposing functions as oncogenes and tumor suppressors have been described. With regard to the regulation of TFF expression, epigenetic mechanisms as well as the involvement of various miRNAs are new, promising aspects in the field of cancer research. This review will summarize current knowledge about the expression and regulation of TFF peptides and the involvement of TFF peptides in tumor biology and cancerogenesis.

Differential regional and cellular distribution of TFF3 peptide in the human brain

TFF3 is a member of the trefoil factor family (TFF) predominantly secreted by mucous epithelia. Minute amounts are also expressed in the immune system and the brain. In the latter, particularly the hypothalamo-pituitary axis has been investigated in detail in the past. Functionally, cerebral TFF3 has been reported to be involved in several processes such as fear, depression, learning and object recognition, and opiate addiction. Furthermore, TFF3 has been linked with neurodegenerative and neuropsychiatric disorders (e.g., Alzheimer's disease, schizophrenia, and alcoholism). Here, using immunohistochemistry, a systematic survey of the TFF3 localization in the adult human brain is presented focusing on extrahypothalamic brain areas. In addition, the distribution of TFF3 in the developing human brain is described. Taken together, neurons were identified as the predominant cell type to express TFF3, but to different extent; TFF3 was particularly enriched in various midbrain and brain stem nuclei. Besides, TFF3 immunostaining staining was observed in oligodendroglia and the choroid plexus epithelium. The wide cerebral distribution should help to explain its multiple effects in the CNS.

Trefoil factor family peptides TFF1 and TFF3 in the nervous tissues of developing mouse embryo

Trefoil factor family peptides (TFF1, TFF2, and TFF3) are predominantly found in mucous epithelia of various organs. However, they have also been reported in the nervous tissue, particularly mouse, rat, porcine, and human brain. The aim of this research was to determine the presence of TFF1 and TFF3 in the nervous system of developing mouse embryo. Mouse embryos, at the stages E15 to E17 were isolated, fixed in 4% paraformaldehyde and embedded in paraffin blocks. Sagittal 6µm sections were made, processed for immunohistochemistry, and incubated with anti-TFF1 or anti-TFF3 primary polyclonal rabbit antibodies. Labeled streptavidin-biotin method was used for TFF detection. TFF1 and 3 were found in the cytoplasm of ganglion cell somata, while TFF3 staining was also visible in the cytoplasm of neurons in different areas and nuclei of brain and medulla oblongata. Neurons in the gray matter of spinal cord were also TFF1 and TFF3 positive, and signal for both peptides was found in the choroid plexus. TFF peptides might be involved in the complex processes of nervous system development and differentiation and brain plasticity.

Expression and localization of trefoil factor family genes in rat submandibular glands

The trefoil factor (TFF) family, which comprises TFF1, TFF2 and TFF3, plays an essential role in epithelial regeneration within the gastrointestinal tract. All three TFFs are present in human saliva; TFF3 is the predominant trefoil peptide. Little is known about the expression and tissue distribution of TFFs in rats, which are commonly used as a model system for human studies. We investigated the localization of the TFF genes that encode secretory peptides in rat submandibular glands (SMG). All three TFFs were expressed in rat SMG, although their location varied. Substantial amounts of TFF1 were detected only in the cytoplasm of epithelial cells in the SMG granular convoluted tubules (GCT), while TFF2 and TFF3 were widely distributed in the cytoplasm of epithelial cells of intercalated ducts (ID), striated ducts (SD) and interlobular ducts (ILD). The three TFFs also were detected especially in the lumens of the SD and ILD. Semi-quantitative RT-PCR and in situ hybridization experiments confirmed TFF1, TFF2 and TFF3 mRNA expressions in the SMG. Greater expression of TFF peptides and mRNA was observed in male rats than in females. The broad expression of TFFs in rat SMG cells and lumens suggests that TFFs function in this organ by their secretion into the duct lumens. We also found differences in TFF expression profiles between rat and human SMG; therefore, caution should be exercised when using rats as a model for human TFF studies.

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.

The intestinal trefoil factor (Tff3), also expressed in the inner ear, interacts with peptides contributing to apoptosis

The 3 members of the mammalian trefoil factor family (TFF) are expressed and secreted as cytoprotective peptides along the entire length of the normal gastrointestinal tract. More recently, they were shown to display multifunctional properties. Goblet cells of the small and large intestine constitute a major source for the synthesis of the third family member, TFF3 (formerly intestinal trefoil factor, ITF). TFF3, like the other family members, is rapidly up-regulated in response to physical wounding of the digestive tract. In addition, Tff3 was also detected in the posterior pituitary gland. Apart from this Tff3 function as a neuropeptide, also presence of Tff3 in the mouse cochlea was noted and Tff3-deficient animals display hearing impairment and accelerated presbyacusis. To elucidate Tff3's mode of function and its unexpected contribution to the hearing process, we strived to determine Tff3's interacting partners and to establish the functional network. To this end, we used a protein-protein binding assay based on a specific transcriptional regulation in yeast cells (the yeast-two-hybrid assay). We looked for interacting partners of Tff3 in a mouse cochlea cDNA library (from donors aged 3-15 days, P3-P15). Our data show that several binding candidates exist and that they could contribute to the known involvement of the trefoil peptides to apoptosis.

Lack of Tff3 peptide results in hearing impairment and accelerated presbyacusis

Tff peptides are secreted mainly by the gastrointestinal epithelial cells and their primary role is maintaining normal structure and function of mucous epithelia. Ongoing studies on their expression pattern have disclosed other sites of their synthesis thus revealing additional physiological functions in the organism. Here we present new data about Tff3 expression in the cochlea of the rodent inner ear. On the basis of RT-PCR we describe the presence of Tff3 transcripts in both, a mouse cDNA library isolated from whole cochleae from postnatal days 3-15 (P3-P15), and also in cochlear tissue. By using a riboprobe for the fragment containing exon 1, 2 and 3 of Tff3, in situ hybridization, localized Tff3 signals in neurons of spiral ganglion and vestibular organ. We did not observe any abnormalities in the middle ear of Tff3 knock-out mice, neither did histological examination of the inner ear indicate any gross morphological changes in the cochlea. However, ABR (auditory evoked brain stem responses) audiograms revealed that the Tff3 knock-out animals show an accelerated presbyacusis and a hearing loss of about 15 dB at low frequencies increasing to 25 dB loss at higher frequencies. These findings suggest that Tff3 could play a role in neurosensory signaling. Further studies are needed to clarify this new function in the auditory system.

Localization of TFF3 peptide in human esophageal submucosal glands and gastric cardia: differentiation of two types of gastric pit cells along the rostro-caudal axis

TFF3 (trefoil factor family 3), which is a major secretory product of the gastric antrum and the intestine, but which is nearly absent in the gastric corpus, plays a key role in the maintenance of mucosal integrity. Here, we have systematically investigated TFF3 expression in the esophagus and gastric cardia by the use of reverse transcription/polymerase chain reaction (RT-PCR) analysis and immunohistochemistry. Synthesis of TFF3, but not TFF1 or TFF2, is detectable in esophageal submucosal glands. The stratified squamous epithelium is devoid of TFF synthesis. Prominent TFF3 expression starts at the Z-line with a sharply decreasing gradient toward the cardia. Immunohistochemistry has localized TFF3 to surface mucous cells of the proximal cardia. TFF3 distribution differs characteristically from that of TFF1 (secreted primarily by superficial surface mucous cells), whereas TFF3, together with the mucin MUC5AC, is also found in deeper lying cells toward the isthmus. This is the first report of TFF3 as a typical secretory peptide of esophageal submucosal glands and gastric cardia. The different expression patterns of TFF3 and TFF1 in the cardia suggest a stepwise maturation of surface mucous cells from TFF3/MUC5AC-positive cells close to the isthmus to TFF1/TFF3/MUC5AC-positive cells at the pit. The gradient of TFF3 expression along the gastric rostro-caudal axis defines two types of gastric pit cells: those secreting TFF3 in the cardia and the antrum and those nearly devoid of TFF3 synthesis in the corpus. This indicates the special requirement, particularly of the esophagogastric junction, for TFF3-triggered protection and repair.

Trefoil factor family (TFF) expression in the mouse brain and pituitary: changes in the developing cerebellum

Trefoil factor family (TFF) peptides, besides their prominent expression in mucous epithelia, are also synthesized in the central nervous system. Previously TFF1 expression was observed in mouse brain astrocytes, while oxytocinergic neurons of the hypothalamo-pituitary axis are recognized sites of TFF3 synthesis. Here, the expression of TFF1, TFF2, and TFF3 was systematically studied using reverse transcription-polymerase chain reaction (RT-PCR) analysis of dissected adult mouse brain regions including the pituitary. Additionally, the developmental profile of TFF expression in murine cerebral cortex and cerebellum was monitored. Overall, the expression patterns of the three TFF genes differed. The TFF1 and TFF2 profiles shared some similarities, whereas the TFF3 expression pattern was completely different. TFF1 was nearly uniformly, but weakly expressed in all brain regions tested. The TFF1 and TFF2 expression patterns differed characteristically in the pituitary where abundant TFF2 transcription was detected in the anterior and not the posterior lobe and the expression level in males was higher than in females. In contrast, TFF3 expression was limited to the hippocampus, the temporal cortex, and the cerebellum, the latter being surprisingly the major site of expression. Here, TFF3 mRNA appeared to be restricted mainly to neurons and not glial cells. Cerebellar TFF3 expression is clearly developmentally regulated (maximum at P15), indicating a role for TFF3 during postnatal cerebellar development.

TFF3 induced Fos protein expression in the magnocellular oxytocin neurons of the hypothalamus

TFF3 is synthesized in magnocellular oxytocin neurons of the supraoptic (SON) and paraventricular nuclei (PVN) of the rat and human hypothalamus. Here we investigated whether intracerebroventricular (i.c.v.) injection of TFF3 stimulates oxytocin release into the blood and activates Fos protein immunoreactivity in oxytocin neurons of the SON and PVN in rats. The results show that plasma oxytocin concentrations were not altered after i.c.v. injection of TFF3 or vehicle. Fos protein expression was significantly increased in both the SON and PVN after TFF3 injections and double labeling studies showed that the Fos signal was predominantly in oxytocin neurons.

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.

Prostanoids mediate the protective effect of trefoil factor 3 in oxidant-induced intestinal epithelial cell injury: role of cyclooxygenase-2

Trefoil factors are small peptides found in several mammalian tissues including gut, respiratory tract and brain. Their physiological function is not well understood. Among them, trefoil factor 3 (intestinal trefoil factor) is known to be cytoprotective in the gut. However, the molecular mechanism and secondary mediators of trefoil factor 3 action are not known. In the present study, we examined whether the cyclooxygenase pathway is involved in trefoil factor 3 action. We showed that trefoil factor 3 significantly induces the production of prostaglandin E(2) and prostaglandin I(2) in IEC-18 cells (an intestinal epithelial cell line) in a dose dependent manner. Western blot and immunohistochemistry revealed that trefoil factor 3 (2.5 microM) up-regulates the expression of cyclooxygenase-2 but not cyclooxygenase-1 in IEC-18 cells. Treating cells with trefoil factor 3 (10 microM) significantly attenuated reactive oxygen species-induced IEC-18 cell injury. This effect is blocked by NS-398 (10 microM), a selective cyclooxygenase-2 inhibitor. Moreover, we demonstrated that exogenously administered carbacyclin (1 microM, a stable analogue of prostaglandin I(2)) and/or prostaglandin E(2) (1 microM) caused a significant reduction of reactive oxygen species-induced cell injury, mimicking the effect of trefoil factor 3. In summary, our results indicate that trefoil factor 3 activates cyclooxygenase-2 in intestinal epithelium to produce prostaglandin I(2) and prostaglandin E(2), which function as survival factors and mediate the cytoprotective action of trefoil factor 3 against oxidant injury.

Co-localization of TFF3 peptide and oxytocin in the human hypothalamus

TFF-peptides (formerly P domain peptides, trefoil factors) are typical secretory products of many mucous epithelial cells. TFF3 is also synthesized in the hypothalamus and has anxiolytic or anxiogenic activities when injected into the rat amygdala. Here we show by immunohistochemistry that TFF3 is localized to a distinct population of neurons of the human hypothalamic paraventricular and supraoptic nuclei. Generally, TFF3-positive cells are co-localized in oxytocin-producing cells and not in vasopressin-producing cells. Relatively large amounts of TFF3-but not TFF1 and TFF2-are present in the posterior lobe of the human pituitary, where it is probably released into the bloodstream. Furthermore, TFF3 was also detectable in human postmortem cerebrospinal fluid.

Localization of TFF3, a new mucus-associated peptide of the human respiratory tract

Trefoil factor family (TFF)-domain peptides (formerly P-domain peptides, trefoil factors) represent major mucin-associated peptides of the gastrointestinal tract. Here, the first localization studies on TFF3 in the lower respiratory tract of human material are presented. Immunohistochemistry revealed significant accumulation of TFF3 to mucous cells in the acini of submucosal glands and varying amounts in goblet cells at the ductular portions and the surface epithelium. TFF3 appears also as a component of the mucus, for example from patients with chronic bronchitis. Expression of TFF3 was also shown by use of the polymerase chain reaction. In contrast, TFF1 and TFF2 transcripts were hardly detectable in the human respiratory tract. Thus, a structural function of TFF3 for the airway mucus is discussed, possibly together with the mucins MUC5B and MUC5AC.

Differential behavioral effects of TFF peptides: injections of synthetic TFF3 into the rat amygdala

TFF peptides (formerly named P-domain peptides or trefoil factors) are also released from the brain as well as being secreted typically by mucin producing cells. The amygdala, besides the hypothalamus, represents a defined neuronal locality of TFF3 synthesis. In a passive avoidance test synthetic TFF3/monomer or 0.9% sodium chloride (control) was injected bilaterally into the basolateral nucleus of the amygdala of male rats either immediately (consolidation test) or 23 h after a footshock (retrieval test). Application of a low TFF3 dose (2 x 6 pg) decreased avoidance latency in a time dependent manner. In contrast, a high dose (2 x 60 pg) increased avoidance latency. Maximal effects of TFF3 were observed about 24 h after the injection. This bidirectional effect was also observed using the elevated plus-maze test. The locomotor activity on the open arms was significantly increased 24 h after a low dose injection of TFF3 into the amygdala. In contrast, a high-dose injection significantly decreased the activity on the open arms. The results of both tests can be explained by an anxiolytic effect at a low dose and an anxiogenic effect at a high dose of synthetic TFF3/monomer.

The pS2/TFF1 trefoil factor, from basic research to clinical applications

pS2/TFF1 trefoil factor is normally expressed in the stomach, and is found ectopically in gastrointestinal inflammatory disorders and in various carcinomas. It is involved in stomach ontogenesis and in the maintenance of the integrity of the mucosa, and may represent a pharmacological tool for prevention and healing of gastrointestinal ulcerations. In breast cancer, it can be used to select patients suitable for hormone therapy. pS2/TFF1 is a pleiotropic factor involved in mucin polymerization, cell motility, cell proliferation and/or differentiation, and possibly in the nervous system.

Intestinal trefoil factor controls the expression of the adenomatous polyposis coli-catenin and the E-cadherin-catenin complexes in human colon carcinoma cells

Intestinal trefoil factor 3 (TFF3) is a member of the trefoil family of peptides, small molecules constitutively expressed in epithelial tissues, including the gastrointestinal tract. TFF3 has been shown to promote migration of intestinal epithelial cells in vitro and to enhance mucosal healing and epithelial restitution in vivo. In this study, we evaluated the effect of recombinant TFF3 (rTFF3) stimulation on the expression and cellular localization of the epithelial (E)-cadherin-catenin complex, a prime mediator of Ca2+ dependent cell-cell adhesion, and the adenomatous polyposis coli (APC)-catenin complex in HT29, HCT116, and SW480 colorectal carcinoma cell lines. Stimulation by rTFF3 (10(-9) M and 10(-8) M) for 20-24 hr led to cell detachment and to a reduction in intercellular adhesion in HT29 and HCT116 cells. In both cell lines, E-cadherin expression was down-regulated. The expression of APC, alpha-catenin and beta-catenin also was decreased in HT29 cells, with a translocation of APC into the nucleus. No change in either cell adhesion or in the expression of E-cadherin, the catenins, and APC was detected in SW480 cells. In addition, TFF3 induced DNA fragmentation and morphological changes characteristic of apoptosis in HT29. Tyrphostin, a competitive inhibitor of protein tyrosine kinases, inhibited the effects of TFF3. Our results indicate that by perturbing the complexes between E-cadherin, beta-catenin, and associated proteins, TFF3 may modulate epithelial cell adhesion, migration, and survival.

Trefoil peptides: mitogens, motogens, or mirages?

Healing of mucosal damage occurs in two phases: restitution of mucosal integrity followed by remodeling with recreation of mucosal architecture. Models of these phenomena include cryoprobe-induced ulcers, NSAID lesions, and surgical anastomosis. Three trefoil peptides are expressed constitutively by epithelial cells in specific regions of the GI tract: pS2 (gastric), spasmolytic polypeptide (SP, gastric and Brunner's glands), and intestinal trefoil factor (ITF, goblet cells). Altered expression occurs in reparative epithelium and adjacent mucosa. In cryoprobe ulceration, rSP mRNA abundance doubles within 2 h, with rITF mRNA becoming detectable after 2-3 days. TGF-alpha and EGF mRNAs do not increase as rapidly as rSP or to the same extent as rITF. Indomethacin lesions of gastric mucosa show increased SP immunoreactivity deep in damaged glands within hours. Surgical anastomotic damage increases rITF mRNA levels at the ulcer edge and sometimes rSP mRNA and peptide in para-anastomotic crypts. Initially, trefoil peptides were viewed as mitogens. However, they are in fact motogens, able to promote cell migration, and may possibly be morphogens. Interactions occur between trefoils and other wound healing peptides (FGFs and EGF). Trefoil peptides appear to be of considerable importance to mucosal healing and might constitute a biologic target of therapeutic relevance.

Intestinal trefoil factor (TFF 3) and pS2 (TFF 1), but not spasmolytic polypeptide (TFF 2) mRNAs are co-expressed in normal, hyperplastic, and neoplastic human breast epithelium

pS2-TFF 1 is expressed in breast cancers and has been investigated as a potential prognostic factor reflecting oestrogen dependence. The relationship to the expression of other trefoil peptides, human spasmolytic polypeptide (hSP-TFF 2) and intestinal trefoil factor (hITF/hPI.B-TFF 3) is documented here. Fifty-seven breast specimens were selected from surgical pathology archives and included five normal breasts (two lactating), seven benign proliferative lesions, 11 ductal carcinomas in situ (DCIS), three lobular carcinomas in situ (LCIS), 24 invasive ductal carcinomas (IDC), and seven invasive lobular carcinomas (ILC). The comparative distribution of trefoil mRNAs was assessed by in situ hybridization using 35S-labelled riboprobes and immunohistochemical staining for pS2-TFF 1 and hSP-TFF 2. pS2-TFF 1 and hITF/hPI.B-TFF 3 mRNA were focally present at low signal intensity in normal and benign breast. Both pS2-TFF 1 and hITF/hPI.B-TFF 3 were expressed in all DCIS, LCIS and ILC, and 21/24 IDC. Overall, expression patterns of pS2-TFF 1 and hITF/hPI.B-TFF 3 coincided, but hITF/hPI.B-TFF 3 mRNA was usually found in a greater proportion of cells. Expression of hSP-TFF 2 peptide or mRNA was not detected in any of these cases. MCF 7 breast carcinoma cells also expressed hITF/hPI.B-TFF 3 and pS2-TFF 1 mRNAs but not hSP-TFF 2. hITF/hPI.B-TFF 3 co-expression with pS2-TFF 1 may act as a prognostic factor, but also raises questions about the regulatory pathway for pS2-TFF 1 hITF/hPI.B-TFF 3. Trefoil factors have effects on cell motility and spreading in vitro, and co-expression of hITF/hPI.B-TFF 3 with pS2-TFF 1 could be functionally significant if they form a heterodimer or compete for receptor binding. Absence of hSP-TFF 2 expression may be of equal relevance to tumour cell biology.

Trefoil proteins: their role in normal and malignant cells

The three human trefoil proteins pS2, human intestinal trefoil factor (hITF), and human spasmolytic polypeptide (hSP) are expressed principally in the mucosa of the gastrointestinal tract. They are also expressed in a variety of other normal tissues and tumours. This review discusses the pattern of expression of trefoil proteins in cancer, current views on the biological functions of trefoil proteins, and the way in which the expression of trefoil proteins may influence the behaviour of cancer cells.