Synergistic effects of systemic trefoil factor family 1 (TFF1) peptide and epidermal growth factor in a rat model of colitis

Novel therapies for the treatment of colitis are required. We therefore examined the potential value of the trefoil factor family 1 (TFF1) peptide and epidermal growth factor (EGF) alone and in combination. Effects of TFF1- Cys58 +/- EGF on an in vitro HT29 cell wounding model of restitution showed synergistic activity when used in combination. In addition, animals had colitis induced by adding 4% dextran sulphate sodium (DSS) to the drinking water for 7 days and they also received twice daily subcutaneous injections of test peptides. Treatment with TFF1-Cys58 alone (100 microg/kg) reduced histological colitis score by 22%, but the TFF1-Ser58 variant was ineffective. In a second study, TFF1-Cys58 reduced histological colitis score by 15%, EGF (600 microg/kg) by 26%, and an additive response (42% reduction) was demonstrated when used together (P < 0.01 versus either peptide given alone). Similar results were found using tissue myeloperoxidase (MPO) activity as a marker of inflammation. Where clinical risk/benefit seems justified, these initial studies suggest that combination therapy of systemic EGF and TFF peptides may prove useful for treatment of colitis in patients with disease extending beyond the reach of topical (enema) therapy.     

TFF2 (trefoil family factor2) inhibits apoptosis in breast and colorectal cancer cell lines

We have recently demonstrated that human TFF2 inhibits apoptosis in the non-TFF2 expressing breast adenocarcinoma cell line MCF-7. In this study we examined the impact of TFF2 and an anti-TFF2 antibody (hSP3) on the survival of other human adenocarcinoma cell lines; TFF2-positive (LS174T and SW480) and TFF2-negative (MCF-7 and T47D). Addition of TFF2 protected the (TFF2-) lines but had no effect on those constitutively expressing TFF2. Blocking with hSP3 significantly increased apoptosis in the (TFF2+) cell lines with minimal effect on the (TFF2-) cells. Our results show that the cytoprotective effect of TFF2 seen in MCF-7 cells is not cell line-specific and can be abrogated by inhibition of its expression.     

Autoinduction of the trefoil factor 2 (TFF2) promoter requires an upstream cis-acting element

Most benign brain tumors are associated with loss of the Nf2 gene tumor suppressor product schwannomin/merlin. Interactions between schwannomin fragments have given rise to hypotheses of in vivo schwannomin folding and dimerization. Previously, we showed that schwannomin with missense mutations L360P, L535P, and Q538P alters interaction with betaII-spectrin and Hrs. Using yeast two-hybrid tests of interaction, we now show the effects of 11 Nf2 missense mutations on schwannomin self-interaction as well as schwannomin interaction with Hrs isoforms 1 and 2, betaII-spectrin, and p110. Missense mutations L46R and K364I significantly decreased affinity of schwannomin for binding all interacting proteins. The schwannomin L46R mutation may result in a complex conformational change that alters folding and denies betaII-spectrin access to an intact binding site in the C-terminal half of schwannomin. We show that unique inter- and intramolecular interactions occur for schwannomin isoform 2, suggesting that this schwannomin isoform has unique functional properties compared to schwannomin isoform 1.     

Effect of ectopic expression of rat trefoil factor family 3 (intestinal trefoil factor) in the jejunum of transgenic mice

To further examine the function of the trefoil factor family (TFF), the expression of which is up-regulated at sites of injury, we have produced transgenic mice that chronically express rat TFF3 within the jejunum (using a rat fatty acid-binding protein promoter). The expression of rat TFF3 was limited to the villi of the jejunum and had no effect on base-line morphology. Rat TFF3 expression did result, however, in a reduced sensitivity to indomethacin (85 mg/kg subcutaneously), which only caused a 29% reduction in villus height in transgenics versus 51% reduction in controls (p < 0.01). Indomethacin increased initial intestinal epithelial cell proliferation and migration, but the presence of rat TFF3 caused no additional change in proliferation (bromodeoxyuridine), cell migration ([(3)H]thymidine and bromodeoxyuridine), apoptosis (terminal deoxyuridine nucleotidyl nick end labeling), or E-cadherin immunostaining. In vitro studies following changes in resistance of intestinal strips in Ussing chambers (voltage-clamp technique) showed increased base-line resistance in the rat TFF3-expressing region (326 +/- 60 versus 195 +/- 48 ohm.cm(2) in controls, p < 0.05) and reduced the fall in resistance following HCl exposure by about 40% (p < 0.01). Overexpression of TFF3 stabilizes the mucosa against noxious agents, supporting its role in mucosal protection/repair. It may therefore provide a novel approach to the prevention and/or treatment of intestinal ulceration.     

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

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

Trefoil factor family (TFF) peptides and cancer progression

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

High trefoil factor 1 (TFF1) expression in human retinoblastoma cells correlates with low growth kinetics, increased cyclin-dependent kinase (CDK) inhibitor levels and a selective down-regulation of CDK6

Trefoil factor family (TFFs) peptides facilitate epithelial restitution, but also effect cell proliferation and apoptosis of normal and various cancer cell lines. In a recent study by our group, TFF2 expression was demonstrated in the murine retina, where it exhibits pro-proliferative and pro-apoptotic effects. In the present study, we investigated the expression and function of TFF peptides in eight human retinoblastoma cell lines. TFF1 was the only TFF peptide expressed at detectable levels in immunoblots of retinoblastoma cells. TFF1 expression levels were highly variable in different retinoblastoma cell lines and negatively correlated with cell growth curves. Recombinant human TFF1 had a negative effect on cell viability and caused a reduction in cell proliferation. Retinoblastoma cell lines with high TFF1 expression levels exhibited a selective down-regulation of cyclin-dependent kinase (CDK) 6, whereas CDK4 and CDK2 seem to be unaffected by TFF1 expression. In immunocytochemical studies, we observed a nuclear co-localization of TFF1 and CDK2 in Cajal bodies (CBs). In high TFF1 expressing human retinoblastoma cell lines CBs were smaller and higher in number compared to retinoblastoma lines with low TFF1 expression, indicating differences in cell cycle status between the different retinoblastoma cell lines. Our data further support the notion for a potential tumor suppressor function of TFF1. The nuclear localization of TFF1 in CBs—considered to play a role in cell cycle progression, potentially acting as a platform for CDK-cyclin function—offers a new impetus in the ongoing search for potential TFF1 interacting proteins.     

Solution structure of the disulfide-linked dimer of human intestinal trefoil factor (TFF3): the intermolecular orientation and interactions are markedly different from those of other dimeric trefoil proteins

The trefoil protein TFF3 forms a homodimer (via a disulfide linkage) that is thought to have increased biological activity over the monomer. The solution structure of the TFF3 dimer has been determined by NMR and compared with the structure of the TFF3 monomer and with other trefoil dimer structures (TFF1 and TFF2). The most significant structural differences between the trefoil domain in the monomer and dimer TFF3 are in the orientations of the N-terminal 3(10)-helix (residues 10-12) and in the presence in the dimer of an additional 3(10)-helix (residues 53-55) outside of the core region. The TFF3 dimer forms a more compact structure as compared with the TFF1 dimer where the two trefoil domains are connected by a flexible region with the monomer units being at variable distances from each other and in many different orientations. Although TFF2 is also a compact structure, the dispositions of its monomer units are very different from those of TFF3. The structural differences between the dimers result in the two putative receptor/ligand binding sites that remain solvent exposed in the dimeric structures having very different dispositions in the different dimers. Such differences have significant implications for the mechanism of action and functional specificity for the TFF class of proteins.     

The trefoil factor interacting protein TFIZ1 binds the trefoil protein TFF1 preferentially in normal gastric mucosal cells but the co-expression of these proteins is deregulated in gastric cancer

The gastric tumour suppressor trefoil protein TFF1 is present as a covalently bound heterodimer with a previously uncharacterised protein, TFIZ1, in normal human gastric mucosa. The purpose of this research was firstly to examine the molecular forms of TFIZ1 present, secondly to determine if TFIZ1 binds other proteins apart form TFF1 in vivo, thirdly to investigate if TFIZ1 and TFF1 are co-regulated in normal gastric mucosa and fourthly to determine if their co-regulation is maintained or disrupted in gastric cancer. We demonstrate that almost all human TFIZ1 is present as a heterodimer with TFF1 and that TFIZ1 is not bound to either of the other two trefoil proteins, TFF2 and TFF3. TFIZ1 and TFF1 are co-expressed by the surface mucus secretory cells throughout the stomach and the molecular forms of each protein are affected by the relative abundance of the other. TFIZ1 expression is lost consistently, early and permanently in gastric tumour cells. In contrast, TFF1 is sometimes expressed in the absence of TFIZ1 in gastric cancer cells and this expression is associated with metastasis (lymph node involvement: p=0.007). In conclusion, formation of the heterodimer between TFIZ1 and TFF1 is a specific interaction that occurs uniquely in the mucus secretory cells of the stomach, co-expression of the two proteins is disrupted in gastric cancer and expression of TFF1 in the absence of TFIZ1 is associated with a more invasive and metastatic phenotype. This indicates that TFF1 expression in the absence of TFIZ1 expression has potentially deleterious consequences in gastric cancer.