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

The structural integrity of human TFF1 under reducing conditions

The trefoil factor family (TFF) comprises three secretory peptides (TFF1, TFF2, TFF3) that regulate diverse physiological processes to maintain gastrointestinal mucosal integrity and homeostasis. The TFF domain is stabilized by six conserved cysteine residues forming three intramolecular disulfide bonds. In this work, we investigated human TFF1 domain stability against increasing concentrations of the reducing agent tris(2-carboxyethyl)phosphine (TCEP). Experiments revealed high resistance of the disulfide bonds within the TFF1 domain to reduction compared to two reference peptides with similar three-disulfide frameworks, namely the bovine pancreatic trypsin inhibitor (BPTI) and the peptide drug linaclotide. Full reduction of TFF1 was only achieved with a large excess of TCEP (150-fold), and no partially reduced intermediates were observed, supporting a compact TFF1 domain. This TFF1 domain stability was supported by extensive all-atom molecular dynamics simulations for a total of 24 μs of all possible combinatorial states of disulfide bond reduction. Despite minor structural and conformational changes observed upon reduction, the domain substantially retained its overall compactness and solvent exposure when only one or two disulfide bonds were removed. The reduced cysteine residues did not undergo large structural rearrangements and remained buried. The loss of covalent disulfide bonds upon reduction was counterbalanced through persistent non-covalent interactions. These molecular simulations explained why TFF1 could not be partially reduced and alkylated during the experiments despite titrating different TCEP concentrations in the presence of alkylating agents. Our findings provide the first insights into the remarkable stability of the human TFF domain under reducing conditions, supporting its functional resilience upon expression and secretion throughout the human body.

Role of trefoil factors in maintaining gut health in food animals

It is imperative to preserve the integrity of the gastrointestinal system in spite of the persistent existence of harmful chemicals and microbial flora in the gut. This is made possible by essential healing initiators called Trefoil factors which helps in mucosal reconstitution and tissue development on the gastrointestinal surface. The trefoil factors are a class of abundant secreted proteins that are essential for epithelial continuity (TFFs). Trefoil factor family (TFF) proteins are biologically active peptides that play significant role in safeguarding, restoring and continuity of the gastrointestinal tract (GIT) epithelium, through collaborative modulations with mucins in the mucosal layer. These peptides are readily produced in reaction to epithelial damage in the digestive tract, thereby contributing to the healing and restituting of the epithelial layers of the intestine. In addition, considerable evidence indicated that TFF peptides trigger proliferation, migration and angiogenesis, all which are crucial processes for wound healing. There is also increasing evidence that TFF peptides modulate the mucosal immune system. These protective properties, suggest that dietary manipulation strategies targeted at enhancing the expression and synthesis of TFF peptides at optimal levels in the GIT epithelium, may constitute a plausible alternative strategy to the use of in-feed antibiotic growth promoters to maintain epithelial integrity and promote resistance to enteric pathogens. This review describes TFF peptides, with importance to their biological functions and involvement in gastrointestinal mucosal protection and repair in food animals.

Licorice flavonoid alleviates gastric ulcers by producing changes in gut microbiota and promoting mucus cell regeneration

Licorice flavonoid (LF) is the main component of Glycyrrhizae Radix et Rhizoma, a "medicine food homology" herbal medicine, which has anti-digestive ulcer activity, but the mechanism in anti-gastric ulcer (GU) remains to be elucidated. In this study, we manifested that LF increased the viability of human gastric mucosal epithelial (GES-1) cells, attenuated ethanol (EtOH)-induced manifestations, reduced histological injury, suppressed inflammation, and restored gastric mucosal barrier in GU rats. After LF therapy, the EtOH-induced gut dysbiosis was partly modulated, and short-chain fatty acids (SCFAs) like butyric acid, propionic acid, and valeric acid were found in higher concentrations. We discovered that the majority of genera that increased in the GU group had a negative correlation with SCFAs in the intestinal tract. In addition, LF-upregulated SCFAs boosted mucus secretion in the gastric epithelium and the expression of mucoprotein (MUC) 5AC and MUC6, particularly the MUC5AC in the gastric foveola. Moreover, LF triggered the EGFR/ERK signal pathway which promoted gastric mucus cell regeneration. Therefore, the findings indicated that LF could inhibit inflammation, promote mucosal barrier repair and angiogenesis, regulate gut microbiota and SCFA metabolism; more importantly, promote epithelial proliferation via activation of the EGFR/ERK pathway, exerting a protective and regenerative effect on the gastric mucosa.

Tff3 Deficiency Differentially Affects the Morphology of Male and Female Intestines in a Long-Term High-Fat-Diet-Fed Mouse Model

Trefoil factor family protein 3 (Tff3) protects the gastrointestinal mucosa and has a complex mode of action in different tissues. Here, we aimed to determine the effect of Tff3 deficiency on intestinal tissues in a long-term high-fat-diet (HFD)-fed model. A novel congenic strain without additional metabolically relevant mutations (Tff3-/-/C57Bl6NCrl strain, male and female) was used. Wild type (Wt) and Tff3-deficient mice of both sexes were fed a HFD for 36 weeks. Long-term feeding of a HFD induces different effects on the intestinal structure of Tff3-deficient male and female mice. For the first time, we found sex-specific differences in duodenal morphology. HFD feeding reduced microvilli height in Tff3-deficient females compared to that in Wt females, suggesting a possible effect on microvillar actin filament dynamics. These changes could not be attributed to genes involved in ER and oxidative stress, apoptosis, or inflammation. Tff3-deficient males exhibited a reduced cecal crypt depth compared to that of Wt males, but this was not the case in females. Microbiome-related short-chain fatty acid content was not affected by Tff3 deficiency in HFD-fed male or female mice. Sex-related differences due to Tff3 deficiency imply the need to consider both sexes in future studies on the role of Tff in intestinal function.

Transcriptomic (DNA Microarray) and Metabolome (LC-TOF-MS) Analyses of the Liver in High-Fat Diet Mice after Intranasal Administration of GALP (Galanin-like Peptide)

The aim of this research was to test the efficacy and potential clinical application of intranasal administration of galanin-like peptide (GALP) as an anti-obesity treatment under the hypothesis that GALP prevents obesity in mice fed a high-fat diet (HFD). Focusing on the mechanism of regulation of lipid metabolism in peripheral tissues via the autonomic nervous system, we confirmed that, compared with a control (saline), intranasally administered GALP prevented further body weight gain in diet-induced obesity (DIO) mice with continued access to an HFD. Using an omics-based approach, we identified several genes and metabolites in the liver tissue of DIO mice that were altered by the administration of intranasal GALP. We used whole-genome DNA microarray and metabolomics analyses to determine the anti-obesity effects of intranasal GALP in DIO mice fed an HFD. Transcriptomic profiling revealed the upregulation of flavin-containing dimethylaniline monooxygenase 3 (Fmo3), metallothionein 1 and 2 (Mt1 and Mt2, respectively), and the Aldh1a3, Defa3, and Defa20 genes. Analysis using the DAVID tool showed that intranasal GALP enhanced gene expression related to fatty acid elongation and unsaturated fatty acid synthesis and downregulated gene expression related to lipid and cholesterol synthesis, fat absorption, bile uptake, and excretion. Metabolite analysis revealed increased levels of coenzyme Q10 and oleoylethanolamide in the liver tissue, increased levels of deoxycholic acid (DCA) and taurocholic acid (TCA) in the bile acids, increased levels of taurochenodeoxycholic acid (TCDCA), and decreased levels of ursodeoxycholic acid (UDCA). In conclusion, intranasal GALP administration alleviated weight gain in obese mice fed an HFD via mechanisms involving antioxidant, anti-inflammatory, and fatty acid metabolism effects and genetic alterations. The gene expression data are publicly available at NCBI GSE243376.

Trefoil Family Factor Peptide 1-A New Biomarker in Liquid Biopsies of Retinoblastoma under Therapy

Effective management of retinoblastoma (RB), the most prevalent childhood eye cancer, depends on reliable monitoring and diagnosis. A promising candidate in this context is the secreted trefoil family factor peptide 1 (TFF1), recently discovered as a promising new biomarker in patients with a more advanced subtype of retinoblastoma. The present study investigated TFF1 expression within aqueous humor (AH) of enucleated eyes and compared TFF1 levels in AH and corresponding blood serum samples from RB patients undergoing intravitreal chemotherapy (IVC). TFF1 was consistently detectable in AH, confirming its potential as a biomarker. Crucially, our data confirmed that TFF1-secreting cells within the tumor mass originate from RB tumor cells, not from surrounding stromal cells. IVC-therapy-responsive patients exhibited remarkably reduced TFF1 levels post-therapy. By contrast, RB patients' blood serum displayed low-to-undetectable levels of TFF1 even after sample concentration and no therapy-dependent changes were observed. Our findings suggest that compared with blood serum, AH represents the more reliable source of TFF1 if used for liquid biopsy RB marker analysis in RB patients. Thus, analysis of TFF1 in AH of RB patients potentially provides a minimally invasive tool for monitoring RB therapy efficacy, suggesting its importance for effective treatment regimens.

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).

Emerging Role of Epigenetic Modifiers in Breast Cancer Pathogenesis and Therapeutic Response

Breast cancer pathogenesis, treatment, and patient outcomes are shaped by tumor-intrinsic genomic alterations that divide breast tumors into molecular subtypes. These molecular subtypes often dictate viable therapeutic interventions and, ultimately, patient outcomes. However, heterogeneity in therapeutic response may be a result of underlying epigenetic features that may further stratify breast cancer patient outcomes. In this review, we examine non-genetic mechanisms that drive functional changes to chromatin in breast cancer to contribute to cell and tumor fitness and highlight how epigenetic activity may inform the therapeutic response. We conclude by providing perspectives on the future of therapeutic targeting of epigenetic enzymes, an approach that holds untapped potential to improve breast cancer patient outcomes.

Pharmacological targeting of gastric mucosal barrier with traditional Chinese medications for repairing gastric mucosal injury

Introduction: The gastric mucosa (GM) is the first barrier and vital interface in the stomach that protects the host from hydrochloric acid in gastric juice and defends against exogenous insults to gastric tissues. The use of traditional Chinese medications (TCMs) for the treatment of gastric mucosal injury (GMI) has long-standing history and a good curative effect. Whereas there are poor overall reports on the intrinsic mechanisms of these TCM preparations that pharmacology uses to protect body from GMI, which is crucial to treating this disease. These existing reviews have deficiencies that limit the clinical application and development of both customary prescriptions and new drugs. Methods: Further basic and translational studies must be done to elucidate the intrinsic mechanisms of influence of these TCM preparations. Moreover, well-designed and well-conducted experiences and clinical trials are necessary to ascertain the efficacy and mechanisms of these agents. Therefore, this paper presents a focused overview of currently published literature to assess how TCMs action that facilitates the cures for GMI. It offers a whole train of current state of pharmacological evidence, identifies the pharmacological mechanisms of TCMs on GM, and highlights that remarkable capacity of TCMs to restore GM after damage. Results: These TCMs preparations promote the repair of multicomponent targets such as the gastric mucus, epithelial layer, blood flow (GMBF) and lamina propria barrier. Summary: Overall, this study has summarized the essential regulatory mechanisms and pharmacological efficacy of TCMs on new and productive therapeutic targets. Discussion: This review provides an avenue for studying various drugs with potentially promising effects on mucosal integrity, as well as subsequent pharmacological studies, clinical applications, and new drug development.

IgG Fc-binding protein positively regulates the assembly of pore-forming protein complex βγ-CAT evolved to drive cell vesicular delivery and transport

Cell membranes form barriers for molecule exchange between the cytosol and the extracellular environments. βγ-CAT, a complex of pore-forming protein (PFP) BmALP1 (two βγ-crystallin domains with an aerolysin pore-forming domain) and the trefoil factor BmTFF3, has been identified in toad Bombina maxima. It plays pivotal roles, via inducing channel formation in various intra- or extra- cellular vesicles, as well as in nutrient acquisition, maintaining water balance, and antigen presentation. Thus, such a protein machine should be tightly regulated. Indeed, BmALP3 (a paralog of BmALP1) oxidizes BmALP1 to form a water-soluble polymer, leading to dissociation of the βγ-CAT complex and loss of biological activity. Here, we found that the B. maxima IgG Fc-binding protein (FCGBP), a well-conserved vertebrate mucin-like protein with unknown functions, acted as a positive regulator for βγ-CAT complex assembly. The interactions among FCGBP, BmALP1, and BmTFF3 were revealed by co-immunoprecipitation assays. Interestingly, FCGBP reversed the inhibitory effect of BmALP3 on the βγ-CAT complex. Furthermore, FCGBP reduced BmALP1 polymers and facilitated the assembly of βγ-CAT with the biological pore-forming activity in the presence of BmTFF3. Our findings define the role of FCGBP in mediating the assembly of a PFP machine evolved to drive cell vesicular delivery and transport.

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.

Transcriptomic analysis reveals an association of FCGBP with Parkinson’s disease

Transcriptomics in Parkinson’s disease (PD) offers new insights into the molecular mechanism of PD pathogenesis. Several pathways, such as inflammation and protein degradation, have been identified by differential gene expression analysis. Our aim was to identify gene expression differences underlying the disease etiology and the discovery of pre-symptomatic risk biomarkers for PD from a multicenter study in the context of the PROPAG-AGEING project. We performed RNA sequencing from 47 patients with de novo PD, 10 centenarians, and 65 healthy controls. Using identified differentially expressed genes, functional annotations were assigned using gene ontology to unveil significant enriched biological processes. The expression of 16 selected genes was validated using OpenArray® assays and samples from independent cohorts of 201 patients with advanced PD, 340 healthy siblings of PD patients, and 177 healthy controls. Differential gene expression analysis identified higher FCGBP expression in patients with de novo PD compared with healthy controls and compared with centenarians. Furthermore, FCGBP showed no differences in terms of population origin or aging process. The increased FCGBP expression was validated in patients with advanced PD and their siblings. Thus, we provided evidence for an upregulation of FCGBP mRNA levels not only in patients with PD but also in individuals at putative higher risk of PD, suggesting that it could be important in gut–brain PD interaction, mediating the connection between microbiota and intestinal inflammatory processes, as well as neuroinflammation and neurodegeneration.

TFF1 gene single nucleotide polymorphism (rs3761376) and colorectal cancer risk

INTRODUCTION

Trefoil Factor 1 (TFF1) is a secretory peptide with gastrointestinal protective functions. Abnormal TFF1 expression is reported in some cancers and functional promoter polymorphism in TFF1 is believed to be associated with risk of gastric cancer. We evaluated rs3761376 in a sample of Iranian patients with colorectal cancer.

METHODS

Peripheral blood samples were taken from pathology confirmed cases of colorectal cancer and healthy volunteers. Genotyping was carried out using Restriction Fragment Length Polymorphism (RFLP) PCR. Any association with clinicopathologic data was assessed by SPSS version 19.

RESULTS

A total of 245 participants, including 122 patients with cancer and 123 non-cancer subjects were enrolled. Age, body mass index, and smoking habits were not significantly different between the two groups (P > 0.05). Distribution of TFF1 genotypes was not found to be associated with colorectal cancer. However, distant metastasis was more prevalent in carriers of the mutant allele.

CONCLUSION

TFF1 rs3761376 was not associated with colorectal cancer but it may be involved in metastasis. Therefore, further investigation is warranted to determine this relationship.

Role of the mucin-like glycoprotein FCGBP in mucosal immunity and cancer

IgGFc-binding protein (FCGBP) is a mucin first detected in the intestinal epithelium. It plays an important role in innate mucosal epithelial defense, tumor metastasis, and tumor immunity. FCGBP forms disulfide-linked heterodimers with mucin-2 and members of the trefoil factor family. These formed complexes inhibit bacterial attachment to mucosal surfaces, affect the motility of pathogens, and support their clearance. Altered FCGBP expression levels may be important in the pathologic processes of Crohn’s disease and ulcerative colitis. FCGBP is also involved in regulating the infiltration of immune cells into tumor microenvironments. Thus, the molecule is a valuable marker of tumor prognosis. This review summarizes the functional relevance and role of FCGBP in immune responses and disease development, and highlights the potential role in diagnosis and predicting tumor prognosis.

Self-Renewal and Cancers of the Gastric Epithelium: An Update and the Role of the Lectin TFF1 as an Antral Tumor Suppressor

In 2020, gastric cancer was the fourth leading cause of cancer deaths globally. About 90% of gastric cancers are sporadic and the vast majority are correlated with Helicobacter pylori infection; whereas familial clustering is observed in about 10% of cases. Gastric cancer is now considered to be a disease originating from dysregulated self-renewal of the gastric glands in the setting of an inflammatory environment. The human stomach contains two types of gastric units, which show bi-directional self-renewal from a complex variety of stem cells. This review focuses on recent progress concerning the characterization of the different stem cell populations and the mainly mesenchymal signals triggering their stepwise differentiation as well as the genesis of pre-cancerous lesions and carcinogenesis. Furthermore, a model is presented (Lectin-triggered Receptor Blocking Hypothesis) explaining the role of the lectin TFF1 as an antral tumor suppressor possibly regulating Lgr5⁺ antral stem cells in a paracrine or maybe autocrine fashion, with neighboring antral gland cells having a role as niche cells.

Salivary Trefoil Factor Family (TFF) Peptides and Their Roles in Oral and Esophageal Protection: Therapeutic Potential

Human saliva is a complex body fluid with more than 3000 different identified proteins. Besides rheological and lubricating properties, saliva supports wound healing and acts as an antimicrobial barrier. TFF peptides are secreted from the mucous acini of the major and minor salivary glands and are typical constituents of normal saliva; TFF3 being the predominant peptide compared with TFF1 and TFF2. Only TFF3 is easily detectable by Western blotting. It occurs in two forms, a disulfide-linked homodimer (Mr: 13k) and a high-molecular-mass heterodimer with IgG Fc binding protein (FCGBP). TFF peptides are secretory lectins known for their protective effects in mucous epithelia; the TFF3 dimer probably has wound-healing properties due to its weak motogenic effect. There are multiple indications that FCGBP and TFF3-FCGBP play a key role in the innate immune defense of mucous epithelia. In addition, homodimeric TFF3 interacts in vitro with the salivary agglutinin DMBT1^gp340. Here, the protective roles of TFF peptides, FCGBP, and DMBT1^gp340 in saliva are discussed. TFF peptides are also used to reduce radiotherapy- or chemotherapy-induced oral mucositis. Thus, TFF peptides, FCGBP, and DMBT1^gp340 are promising candidates for better formulations of artificial saliva, particularly improving wound healing and antimicrobial effects even in the esophagus.

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.

A bioinformatic analysis: the overexpression and clinical significance of FCGBP in ovarian cancer

Fc fragment of IgG-binding protein (FCGBP) is differentially expressed in various tumors. However, the correlation between FCGBP and immune cell infiltration in ovarian cancer remains unclear. FCGBP expression was analyzed using The Cancer Genome Atlas (TCGA) pan-cancer data, and the ovarian cancer expression profile was analyzed using the Gene Expression Omnibus database. The clinical prognostic value of FCGBP was evaluated using clinical survival data from TCGA. Enrichment analysis of FCGBP was performed using the R package clusterProfiler. Based on known immune cell infiltration scores for samples found in TCGA, we analyzed the association between immune cell infiltration level and FCGBP expression. FCGBP was highly expressed and associated with poorer overall survival (p = 0.00051) and disease-specific survival (p = 0.0012) in ovarian cancer and other tumors. Additionally, high FCGBP expression correlated significantly with immune-related gene sets, including those involved in chemokine signaling pathways and innate and adaptive immunity. Further analysis showed that M2 macrophage infiltration increased and M1 macrophage infiltration decreased in tissues with high FCGBP expression. Our study suggests that FCGBP contributes to M2 macrophage polarization by acting as an oncogene in ovarian cancer. FCGBP may represent a clinically helpful biomarker for predicting overall survival of ovarian cancer patients.

A bioinformatic analysis: the overexpression and clinical significance of FCGBP in ovarian cancer

Fc fragment of IgG-binding protein (FCGBP) is differentially expressed in various tumors. However, the correlation between FCGBP and immune cell infiltration in ovarian cancer remains unclear. FCGBP expression was analyzed using The Cancer Genome Atlas (TCGA) pan-cancer data, and the ovarian cancer expression profile was analyzed using the Gene Expression Omnibus database. The clinical prognostic value of FCGBP was evaluated using clinical survival data from TCGA. Enrichment analysis of FCGBP was performed using the R package clusterProfiler. Based on known immune cell infiltration scores for samples found in TCGA, we analyzed the association between immune cell infiltration level and FCGBP expression. FCGBP was highly expressed and associated with poorer overall survival (p = 0.00051) and disease-specific survival (p = 0.0012) in ovarian cancer and other tumors. Additionally, high FCGBP expression correlated significantly with immune-related gene sets, including those involved in chemokine signaling pathways and innate and adaptive immunity. Further analysis showed that M2 macrophage infiltration increased and M1 macrophage infiltration decreased in tissues with high FCGBP expression. Our study suggests that FCGBP contributes to M2 macrophage polarization by acting as an oncogene in ovarian cancer. FCGBP may represent a clinically helpful biomarker for predicting overall survival of ovarian cancer patients.

TFF1 Induces Aggregation and Reduces Motility of Helicobacter pylori

Gastric cancer is considered one of the most common malignancies in humans and Helicobacter pylori infection is the major environmental risk factor of gastric cancer development. Given the high spread of this bacterium whose infection is mostly asymptomatic, H. pylori colonization persists for a long time, becoming chronic and predisposing to malignant transformation. The first defensive barrier from bacterial infection is constituted by the gastric mucosa that secretes several protective factors, among which is the trefoil factor 1 (TFF1), that, as mucin 5AC, binds the bacterium. Even if the protective role of TFF1 is well-documented, the molecular mechanisms that confer a beneficial function to the interaction among TFF1 and H. pylori remain still unclear. Here we analyze the effects of this interaction on H. pylori at morphological and molecular levels by means of microscopic observation, chemiotaxis and motility assays and real-time PCR analysis. Our results show that TFF1 favors aggregation of H. pylori and significantly slows down the motility of the bacterium across the mucus. Such aggregates significantly reduce both flgE and flaB gene transcription compared with bacteria not incubated with TFF1. Finally, our results suggest that the interaction between TFF1 and the bacterium may explain the frequent persistence of H. pylori in the human host without inducing disease.

Trefoil factor 1 and gastrokine 2 inhibit Helicobacter pylori-induced proliferation and inflammation in gastric cardia and distal carcinogenesis

Helicobacter pylori (H. pylori) infection has been associated with non-cardia adenocarcinoma in the stomach, while its role in gastric cardia adenocarcinoma (GCA) remains controversial. In addition, the association between H. pylori and the protective factors trefoil factor 1 (TFF1) and gastrokine 2 (GKN2) in gastroesophageal adenocarcinomas has not been fully investigated. Therefore, the mRNA and protein expression levels of TFF1 and GKN2 in GCA and distal gastric adenocarcinoma (DGA) were analyzed using quantitative PCR (qPCR) and immunohistochemistry, and the association with H. pylori infection was investigated. In addition, the effects of TFF1 and GKN2 overexpression on H. pylori-induced cells were investigated using western blot and reverse transcription-qPCR analysis. The comparative analysis of 16S rRNA-positive mRNA expression between GCA and DGA showed no statistically significant difference. However, the rate of the H. pylori vacuolating toxin A (VacA) genotype was significantly higher in GCA (49.2%) compared with that in DGA (26.9%; P<0.05). H. pylori infection downregulated the mRNA and protein expression levels of TFF1 and GKN2 in gastric tumor tissues, and the mRNA expression level of TFF1 and GKN2 was also markedly decreased in vitro. Furthermore, the cell proliferation varied in H. pylori total protein treatment group with the different doses. Notably, treatment with 20 µg/ml H. pylori total protein for 24 h resulted in the highest cellular proliferation rate. In addition, TFF1 and GKN2 overexpression inversely inhibited H. pylori-induced cell proliferation and upregulated NF-κB, tumor necrosis factor-α, IL-1β, IL-2, IL-4 and IL-6. The results of the present study indicate that H. pylori, particularly the VacA+ strain, plays an important role in GCA pathogenesis in high-risk areas of China, while TFF1/GKN2 inhibits H. pylori-induced cell proliferation and inflammation in GCA and DGA.

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.

Chemical synthesis of human trefoil factor 1 (TFF1) and its homodimer provides novel insights into their mechanisms of action

TFF1 is a key peptide for gastrointestinal protection and repair. Its molecular mechanism of action remains poorly understood with synthetic intractability a recognised bottleneck. Here we describe the synthesis of TFF1 and its homodimer and their interactions with mucins and Helicobacter pylori. Synthetic access to TFF1 is an important milestone for probe and therapeutic development.

Structure, Function, and Therapeutic Potential of the Trefoil Factor Family in the Gastrointestinal Tract

Trefoil factor family peptides (TFF1, TFF2, and TFF3) are key players in protecting, maintaining, and repairing the gastrointestinal tract. Accordingly, they have the therapeutic potential to treat and prevent a variety of gastrointestinal disorders associated with mucosal damage. TFF peptides share a conserved motif, including three disulfide bonds that stabilize a well-defined three-loop-structure reminiscent of a trefoil. Although multiple functions have been described for TFF peptides, their mechanisms at the molecular level remain poorly understood. This review presents the status quo of TFF research relating to gastrointestinal disorders. Putative TFF receptors and protein partners are described and critically evaluated. The therapeutic potential of these peptides in gastrointestinal disorders where altered mucosal biology plays a crucial role in the underlying etiology is discussed. Finally, areas of investigation that require further research are addressed. Thus, this review provides a comprehensive update on TFF literature as well as guidance toward future research to better understand this peptide family and its therapeutic potential for the treatment of gastrointestinal disorders.

Correction: Chemical synthesis of human trefoil factor 1 (TFF1) and its homodimer provides novel insights into their mechanisms of action

Correction for ‘Chemical synthesis of human trefoil factor 1 (TFF1) and its homodimer provides novel insights into their mechanisms of action’ by Nayara Braga Emidio et al., Chem. Commun., 2020, DOI: 10.1039/D0CC02321C.