Peter Gött

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

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

Trefoil factor family domain peptides in the human respiratory tract

Trefoil factor family domain peptides (TFF) are thought to be involved in mucosal epithelial restitution and wound healing of the gastrointestinal tract and are up‐regulated in ulceration and in a variety of solid tumours. It was hypothesized that TFFs are also expressed on mucosal surfaces of the human respiratory tract. Lung tissue, nasal polyps, and sputum samples from seven patients with cystic fibrosis (CF), two with chronic and acute bronchitis, and non‐dysplastic material from two cases of bronchial adenocarcinoma were analysed for TFF expression by immunohistochemistry, immunofluorescence, western blot and RT‐PCR. Expression of TFF1 and TFF3 was observed in material from all patients. TFFs were localized in goblet and ciliated cells, as well as in some submucosal cells of tracheobronchial tissues and nasal polyps from normal and CF individuals. In sputa of patients with CF and with chronic or acute bronchitis, TFF1 and TFF3 were detected by western blotting. Freshly cultivated nasal epithelial cells transcribed and secreted TFFs and mucins, whereas nasal cells cultivated for 6 weeks still expressed mucins, but not TFFs. Secreted TFFs and mucins also bound to the surface of Staphylococcus aureus in infected CF airways. In conclusion, TFF1 and TFF3 are expressed and secreted in normal and inflamed airways. The association of TFFs with bacteria may contribute to the anti‐microbial mucociliary defence system. Copyright

Hepatocyte Nuclear Factor 3 (Winged Helix Domain) Activates Trefoil Factor Gene TFF1 through a Binding Motif Adjacent to the TATAA Box

The winged helix transcription factors HNF-3/FKH (forkhead homologs) activate endodermal-derived and acute-phase gene expression and control gut development in Drosophila. Trefoil factor family (TFFs) peptides are vertebrate products secreted by mucin-producing epithelial cells of the gastrointestinal tract involved in restitution and repair of the mucosa. They are positively regulated in ulcerative and neoplastic conditions. We describe a consensus sequence in human and rodent TFF promoters close to the TATAA box showing striking similarity to the binding site of the HNF-3/FKH family. In gel retardation assays, HNF-3 alpha and beta bound predominantly to the site in TFF1 (formerly pS2) and, to a lesser extent, to the sites in TFF2 or TFF3. Mutations generated in this motif severely impaired transcription of TFF1 reporter genes. Cotransfection with expression vectors of HNF-3alpha and beta, but not the related HFH 11A and B, specifically activated the wild-type TFF1 reporter genes. Activation of endogenous expression of TFF1 by HNF-3 alpha and beta gene products was more than 1000 fold in the pancreatic cell line Capan-2 and fivefold in the gastric cell line MKN-45, whereas the intestinal cell lines HUTU 80 and HT-29 displayed no effect. Thus, HNF-3/FKH factors contribute causally to cell-specific regulation of TFF genes and may explain the acute-phase response of TFF peptides.

Human trefoil peptides: genomic structure in 21q22.3 and coordinated expression.

Trefoil peptides are small secretory proteins characterized by three intrachain disulfide bonds forming the trefoil motif or P-domain. They are abundantly expressed on mucosal surfaces, especially of the gastrointestinal tract. In pathological conditions such as ulcers, metaplasia and neoplasia, their expression is upregulated. Three human trefoil peptides have been described: the estrogen-inducible pS2 protein, the spasmolytic protein and the intestinal trefoil factor. Recently, their role in the maintenance of surface integrity and ulcer healing was discussed. We already mapped the corresponding three genes (BCEI, SML1, TFF3) to the same genomic region (21q22.3). In this paper, we show that the three genes are clustered in a tandemly orientated fashion within 50 kb on a bacterial artificial chromosome (BAC) recombinant. This cluster is located adjacent to D21S19 and the locus order is cen-D21S212-TFF3-SML1-BCEI-D21S19-tel, whereas transcription of all three genes is directed towards the centromere. The gene structure of SML1 exhibits four exons, two of which encode the two separate trefoil motifs. TFF3 and BCEI, both containing one trefoil motif, are composed of three exons each, suggesting gene duplication and exon-shuffling events during evolution. The 5′-flanking region of SML1 was compared to the corresponding region of other trefoil genes. Two motifs with identical sequence and positions are shared between SML1 and BCEI, thus presenting possible targets for stomach-specific gene regulation. Two other motifs are shared within all known human and rat trefoil genes, suggesting a coordinated regulation and/or a common locus-controlling region. Using RT-PCR, a change in the pattern of trefoil gene expression is detected in tissue samples from normal gastric mucosa, hyperplastic polyps, gastric cancer, and gastric cancer cell lines, respectively.

Down-regulation of TFF Expression in Gastrointestinal Cell Lines by Cytokines and Nuclear Factors

Background and Aims: Trefoil peptides (TFF1, TFF2 and TFF3) are acute phase proteins up-regulated in response to gastrointestinal mucosal damage. They promote cell migration, protect and heal the mucosa and may function as tumorsuppressors. We assumed them to be regulated by the proinflammatory cytokines interleukin-1β (IL1β) and interleukin-6 (IL6), which trigger the transcriptional factors NF-ĸB and C/EBPβ. Methods: Following IL1β and IL6 stimulation, expression of TFF genes was analyzed in gastrointestinal cell lines HT-29 and KATO III by reporter gene assays using TFF promoter constructs and by quantitative real-time PCR. NF-ĸB and C/EBPβ were transiently co-expressed. Results: We have functionally identified transcription factors NF-ĸB and C/EBPβ to inhibit transcription of human TFF genes. Down-regulation of TFF transcription is also observed by IL1β and IL6, suggesting crosstalk with or in response to the immune system. IL1β and IL6 caused a 3- to 11-fold reduction in TFF mRNA expression, displayed in real-time PCR. Conclusions: Down-regulation of intestinal trefoil factor TFF3 due to transcriptional repression by IL1β through NF-ĸB as well as by IL6 through C/EBPβ activation in vitro may reflect the situation in vivo and may contribute to ulceration and decreased wound healing during inflammatory bowel disease. Additionally, IL1 and IL6 over-expression in chronic gastritis may lead to mucosal damage and gastric carcinogenesis through transcriptional repression of TFF1 and TFF2.

Patterns of expression of trefoil peptides and mucins in gastric polyps with and without malignant transformation

The expression of two trefoil peptides (TFF1 and TFF2) and four mucins (MUC1, MUC2, MUC5AC, and MUC6) was evaluated by immunohistochemistry and reverse transcription‐polymerase chain reaction (RT‐PCR) in 29 gastric polyps, 10 hyperplastic and 19 adenomatous, eight of which displayed malignant transformation. The aims of this study were to characterize the expression profile of these molecules in each type of polyp and to investigate possible modifications of the profile during the process of malignant transformation. All hyperplastic polyps displayed immunoreactivity for TFF1, MUC5AC, and MUC1 in more than 75 per cent of the cells. In adenomatous polyps, three main phenotypes could be identified: complete gastric phenotype (co‐expression of TFF1 and MUC5AC)—nine cases (47·4 per cent); incomplete gastric phenotype (TFF1‐positive and MUC5AC‐negative)—seven cases (36·8 per cent); non‐gastric (intestinal) phenotype (no expression of TFF1 or MUC5AC)—three cases (15·8 per cent). Data yielded by immunohistochemistry and RT‐PCR showed a good correlation for both TFF1 and TFF2. One hyperplastic and seven adenomatous polyps with villous architecture displayed foci of diffuse and intestinal‐type carcinoma, respectively; in all of these cases, MUC1 expression and signs of gastric differentiation were observed in both the non‐malignant and the carcinomatous component. It is concluded that gastric differentiation is a feature of hyperplastic polyps and of a subset of adenomatous polyps which is shared by early carcinomas arising in some of these polyps, regardless of the histological type of polyp and of carcinoma. Copyright

Aspirin promotes TFF2 gene activation in human gastric cancer cell lines.

Trefoil factor family (TFF) peptides promote cell migration, heal the mucosa and may suppress tumor growth. In reporter gene assays we show that aspirin (1–12 mM) evokes a six‐fold up‐regulation of TFF2, but not TFF1 and TFF3 transcription in human gastrointestinal cell lines. 6 h after application up‐regulation of endogenous TFF2 mRNA was observed. TFF2 transcription was enhanced by indomethacin and arachidonic acid but repressed by staurosporine, suggesting mediation via protein kinase C. We mapped an aspirin responding element −546 to −758 bp upstream of TFF2. Up‐regulation of TFF2 by aspirin may partially explain the chemopreventive potential of low dose aspirin in gastrointestinal carcinogenesis.

Osmotic changes and ethanol modify TFF gene expression in gastrointestinal cell lines

The gastrointestinal tract is exposed to environmental insult as a result of food intake or in pathological conditions such as diarrhoea, and is therefore protected by the mucus layer. As part of it, trefoil peptides (TFFs) are able to modify the visco‐elastic properties of the mucus, protect against experimental ulceration, and promote repair of the epithelia. We investigated, using transient reporter gene assays and RT‐PCR in the gastric carcinoma cell line MKN45 and colon carcinoma cell lines LS174T and HT29, whether ethanol and osmotic changes can modify transcriptional activity of TFFs. In a mild hypotonic environment (200 mosmol/l) all three TFF genes were up‐regulated by at least a factor of 2. In hypertonic medium (400 mosmol/l), TFF1 and TFF3 were down‐regulated, whereas TFF2 was up‐regulated by elevated concentrations of sodium or chloride in MKN45. Raising the osmolality by ethanol resulted in an up‐regulation of TFF3 in both colon cell lines but not in the gastric cell line. We conclude that alteration in TFF gene expression is a response of gut epithelia to deal with osmotic forces and ethanol.

Tracing the evolutionary origin of the TFF-domain, an ancient motif at mucous surfaces.

Mammalian trefoil factor family (TFF)-domain peptides promote gastrointestinal protection, healing and cell migration and may act as tumour suppressors. TFF-like domains also constitute modules of composite proteins like mucin glycoproteins and zona pellucida proteins. Database searches with a modified, less stringent consensus sequence - C-x(5,6)-[ST]-x(3)-C-x(4,5)-C-C-[FYWH]-x(2, 24)-C-[FY] - revealed that ancestors of the TFF-domain arose before amphibian evolution. Eggshell proteins and a zona pellucida-like protein in teleost species, an epidermis-specific protein in a tunicate as well as an open reading frame in a nematode exhibited TFF-like motifs suggesting that they most likely originated in some multicellular organism.

Cloning of contiguous genomic fragments from human chromosome 21 harbouring three trefoil peptide genes

Abstract A group of small peptides with a typical cysteine-rich domain (termed trefoil motif or P-domain) is abundantly expressed at mucosal surfaces of specific normal and neoplastic tissues. Their association with the maintenance of surface integrity was suggested. The first known human trefoil peptide (pS2) was isolated from breast cancer cells (MCF7). Its oestrogen-inducible gene, and the human homologue to the porcine spasmolytic peptide gene (hSP/SML1) appear synchronously expressed in healthy stomach mucosa and several carcinomas of the gastrointestinal tract. Both genes were shown to be localised at 21q22.3. A new trefoil peptide from human intestinal mucosa (hITF/hP1.B) and its gene were described recently. By using suitable oligonucleotide primers and PCR and isolating large (110–250 kb) genomic recombinants cloned in the bacterial artificial chromosome (BAC) system, we present a genomic region from chromosome band 21q22.3 cloned in contiguous sequences and encoding all three members of human P-domain/trefoil peptides proving a physical linkage of all three trefoil peptide genes. Such genomic sequences will provide useful experimental material for analysis of gene regulation, for gene modification experiments and for establishing transgenic cells or animals.