Molecular mechanisms involved in TFF3 peptide-mediated modulation of the E-cadherin/catenin cell adhesion complex

Loss of E-cadherin Activates EGFR-MEK/ERK Signaling, Promoting Cervical Cancer Progression

BACKGROUND/AIM

This study investigated the relationship between E-cadherin down-regulation and enhanced pERK1/2 signaling in cervical cancer, evaluated their combined prognostic impact, and explored potential therapeutic targets.

MATERIALS AND METHODS

We analyzed 188 cervical cancer specimens and 300 normal cervical tissue samples using tissue microarray and immunohistochemistry. Small interfering RNA transfection and western blotting were used to study molecular interactions in cervical cancer cell lines.

RESULTS

We observed a significant inverse correlation between E-cadherin and pERK1/2 expression, as well as poor disease-free survival and overall survival. Additionally, molecular analysis indicated that E-cadherin silencing enhanced ERK signaling and promoted cancer cell proliferation.

CONCLUSION

The findings suggest that E-cadherin and pERK1/2 are crucial biomarkers for cervical cancer prognosis and their interaction provides a potential target for therapeutic interventions. Further studies are recommended to explore these pathways in the clinical setting.

The Urinary Concentration of Trefoil Factor 3 (TFF3) in the Term and Preterm Neonates

BACKGROUND

Distinguishing between a pathologic state and renal development is important in neonatology. Because the assessment of serum creatinine in neonates is not reliable, better biomarkers are needed. Trefoil factor 3 (TFF3) is proposed as a biomarker of kidney injury. The study aimed to assess its urinary concentration in healthy term and stable preterm neonates.

MATERIAL AND METHODS

The study included 80 term and 20 preterm neonates born in the Department of Perinatology of the University Clinical Hospital in Bialystok. Urine was obtained from the term neonates on the 1st day of life and from the preterm neonates on the 1st, 8th, 15th and 22nd day of life. The urinary concentration of TFF3 was determined using a commercially available immunoassay and was normalized for the urinary creatinine concentration (cr.).

RESULTS

The values of TFF3/cr. were higher in the preterm than in the term neonates (p < 0.05) (median (Q1-Q3): 1486.85 (614.92-3559.18) and 317.29 (68.07-671.40) ng/mg cr.). They did not differ in the subsequent days of the preterm neonates' lives. The ROC curve for TFF3/cr. in the preterm and term neonates showed AUC = 0.751 (cut-off value = 1684.25 ng/mg cr.).

CONCLUSIONS

Prematurity is associated with higher urinary excretion of TFF3. Male gender is associated with an increased urinary TFF3 excretion in term neonates.

Intestinal mucus components and secretion mechanisms: what we do and do not know

Damage to the colon mucus barrier, the first line of defense against microorganisms, is an important determinant of intestinal diseases such as inflammatory bowel disease and colorectal cancer, and disorder in extraintestinal organs. The mucus layer has attracted the attention of the scientific community in recent years, and with the discovery of new mucosal components, it has become increasingly clear that the mucosal barrier is a complex system composed of many components. Moreover, certain components are jointly involved in regulating the structure and function of the mucus barrier. Therefore, a comprehensive and systematic understanding of the functional components of the mucus layer is clearly warranted. In this review, we summarize the various functional components of the mucus layer identified thus far and describe their unique roles in shaping mucosal structure and function. Furthermore, we detail the mechanisms underlying mucus secretion, including baseline and stimulated secretion. In our opinion, baseline secretion can be categorized into spontaneous Ca²⁺ oscillation-mediated slow and continuous secretion and stimulated secretion, which is mediated by massive Ca²⁺ influx induced by exogenous stimuli. This review extends the current understanding of the intestinal mucus barrier, with an emphasis on host defense strategies based on fortification of the mucus layer.

The diagnostic and clinicopathological value of trefoil factor 3 in patients with gastric cancer: a systematic review and meta-analysis

OBJECTIVE

To assess the diagnostic value of Trefoil factor 3 (TFF3) and the correlation between TFF3 expression and clinicopathological features in patients with gastric cancer (GC).

METHODS

PubMed, The Cochrane, EMbase, and Web of Science were retrieved comprehensively to collect relevant literature. The search ended on 31 May 2020. All data were analyzed using PubMed, The Cochrane, EMbase, and Web of Science were retrieved to collect relevant articles. All data from the included studies were subjected to meta-analysis using Stata 12.0 software.

RESULTS

Seventeen studies involved 4654 subjects were included. For the diagnostic value of TFF3 for GC, the sensitivity, specificity, and AUC were 0.71, 0.80, and 0.80, respectively. For the clinicopathological value of TFF3, tissue TFF3 expression showed a higher risk of lymph node metastasis (OR 2.20, 95% CI 1.75-2.78, p < 0.001) and muscularis propria invasion (≥T2) (1.51, 1.13-2.03, p = 0.006), as well as worse TNM stage (2.26, 1.63-3.12, p < 0.001) and histological type (1.72, 1.34-2.20, p < 0.001), while no apparent relationship was found for serous membrane invasion (T4), venous invasion, and peritoneal metastasis.

CONCLUSION

TFF3 may be a promising biomarker for GC, and the TFF3 expression is likely to be involved in the invasion, metastasis, and differentiation of GC.

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.

Odyssey of trefoil factors in cancer: Diagnostic and therapeutic implications

Trefoil factors 1, 2, and 3 (TFFs) are a family of small secretory molecules involved in the protection and repair of the gastrointestinal tract (GI). TFFs maintain and restore epithelial structural integrity via transducing key signaling pathways for epithelial cell migration, proliferation, and invasion. In recent years, TFFs have emerged as key players in the pathogenesis of multiple diseases, especially cancer. Initially recognized as tumor suppressors, emerging evidence demonstrates their key role in tumor progression and metastasis, extending their actions beyond protection. However, to date, a comprehensive understanding of TFFs' mechanism of action in tumor initiation, progression and metastasis remains obscure. The present review discusses the structural, functional and mechanistic implications of all three TFF family members in tumor progression and metastasis. Also, we have garnered information from studies on their structure and expression status in different organs, along with lessons from their specific knockout in mouse models. In addition, we highlight the emerging potential of using TFFs as a biomarker to stratify tumors for better therapeutic intervention.

Extracellular production of recombinant sus scrofa trefoil factor 3 by Brevibacillus choshinensis

Trefoil factor 3 (TFF3) is involved in cell adhesion, motility and apoptosis, regulates mucosal immunity and maintains the functional integrity of intestinal epithelia. The upregulation of TFF3 expression in the weaning rat intestine attracted our interest. The present study hypothesized that TFF3 may serve a role in preventing diarrhea in weaning piglets, which is an important consideration in the pig farming industry. Previous recombinant TFF3 protein expression yields obtained from Escherichia coli were too low and the bioactivity of the protein was poor. Hence, this expression system was unsuitable for industrial applications. The present study explored the production of recombinant sus scrofa TFF3 in a Brevibacillus choshinensis (B. choshinensis) expression system, aiming to enhance the expression level of bioactive protein. To achieve this, the sus scrofa TFF3-encoding gene fragment was fused into an E. coli-Brevibacillus shuttle vector pNCMO2. High levels of TFF3 (30 mg/l) were produced and secreted into the B. choshinensis culture medium in soluble form with a molecular mass of 13.6 kDa and high immunoreactivity in western blotting. Thus, Brevibacillus may be used to produce useful mucosal factors for biochemical analyses and mucosal protection, and in industrial applications to produce novel inhibitors of diarrhea.

MicroRNA-7-5p regulates the proliferation and migration of intestinal epithelial cells by targeting trefoil factor 3 via inhibiting the phosphoinositide 3-kinase/Akt signalling pathway

Trefoil factor 3 (TFF3) reconstructs the epithelial barrier by stimulating epithelial cell migration and proliferation, and significantly contributes to intestinal mucosal damage and healing. In a previous study, TFF3 was identified as a novel target of microRNA-7-5p (miR-7-5p). The aim of the present study was to investigate the roles and mechanisms of miR-7-5p in the proliferation and migration of intestinal epithelial cells. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to determine the expression level of miR-7-5p in the experimental groups. In addition, western blot analysis was performed to examine the expression levels of TFF3, phosphoinositide 3-kinase (PI3K), Akt and phosphorylated (p)-AKT when miR-7-5p or TFF3 was overexpressed, and the effects of miR-7-5p and TFF3 on LS174T cell proliferation and migration were simultaneously investigated. miR-7-5p was demonstrated to decrease the expression level of TFF3, and inhibit LS174T cell proliferation and migration, which was accompanied by decreased expression levels of PI3K and p-Akt. miR-7-5p was decreased following combined treatment with the TFF3 plasmid and miR‑7-5p mimics, compared with treatment with miR-7-5p mimics alone, which was accompanied by increased expression levels of TFF3, PI3K and p-Akt, and enhanced LS174T cell proliferation and migration effects. The expression levels of miR-7-5p in the miRNA negative control (NC) + LY294002 group, the miR‑7-5p mimic + LY294002 group, and the miR-7-5p mimic + TFF3 plasmid + LY294002 group were higher than those in the NC group, the miR-7-5p mimic group and the miR-7-5p mimic + TFF3 plasmid group, respectively. Accordingly, the expression level of TFF3 was downregulated and the proliferation and migration ability of the cells was downregulated. The present study demonstrates that overexpressed miR-7-5p may inhibit the proliferation and migration of LS174T cells by targeting the expression of TFF3 via inhibiting the PI3K/Akt signalling pathway. The PI3K/Akt signalling pathway may exert a feedback regulation effect on miR-7-5p, inhibiting the activity of this signalling pathway, which increases the miR-7-5p expression levels and further enhances the effects of miR-7-5p on cell proliferation and migration.

Trefoil factor 3 contributes to the malignancy of glioma via regulating HIF-1α

Trefoil factor 3 (TFF3) plays significant roles in several solid tumors. However, the expression pattern and function of TFF3 in glioblastoma (GBM) have not been reported. Here, we report that expression level of TFF3 significantly elevated in glioma and correlated with the prognosis of glioma patients. Then we found TFF3 promotes proliferation, invasion, and migration and inhibits apoptosis of glioma cells in vitro, and delayed tumor progression in subcutaneous xenograft nude mice, and prolonged the median survival time in orthotopic xenograft mice. Moreover, knockdown of TFF3 reduced the expression of HIF-1α through a hypoxia-independent manner. These findings suggest that targeting TFF3 may offer a novel strategy for therapeutic intervention of malignant gliomas.

TFF3-dependent resistance of human colorectal adenocarcinoma cells HT-29/B6 to apoptosis is mediated by miR-491-5p regulation of lncRNA PRINS

Tumour necrosis factor-α (TNF-α) is a double-edged cytokine associated with pathogenesis of inflammatory-related cancers being also able to induce cancer cell death. In the process of tumour development or metastasis, cancer cells can become resistant to TNF-α. In trefoil factor 3 (TFF3) overexpressing colorectal adenocarcinoma cells (HT-29/B6), we observed enhanced resistance against TNF-α/interferon gamma-induced apoptosis. TFF3 is a secreted small peptide that supports intestinal tissue repair but is also involved in intestinal tumour progression and scattering. We hypothesised that TFF3 rescues intestinal epithelial cancer cells from TNF-α-induced apoptosis by involving regulatory RNA networks. In silico-based expression analysis revealed TFF3-mediated regulation of selected microRNAs as well as long non-coding RNAs (lncRNAs), whereas miR-491-5p was identified to target the lncRNA ‘psoriasis susceptibility-related RNA gene induced by stress’ (PRINS). RNA interference-based gain- and loss-of-function experiments examined miR-491-PRINS axis to exert the TFF3-mediated phenotype. Chemical inhibition of selected pathways showed that phosphatidylinositol 3-kinase/AKT accounts for TFF3-mediated downregulation of miR-491-5p and accumulation of PRINS. Moreover, we showed that PRINS colocalises with PMAIP1 (NOXA) in nuclei of HT-29/B6 possessing inhibitory effects. Immunoprecipitation experiments proved molecular interaction of PMAIP1 with PRINS. Our study provides an insight into RNA regulatory networks that determine resistance of colorectal cancer cells to apoptosis.

Trefoil Factor-3 (TFF3) Stimulates De Novo Angiogenesis in Mammary Carcinoma both Directly and Indirectly via IL-8/CXCR2

Mammary carcinoma cells produce pro-angiogenic factors to stimulate angiogenesis and tumor growth. Trefoil factor-3 (TFF3) is an oncogene secreted from mammary carcinoma cells and associated with poor prognosis. Herein, we demonstrate that TFF3 produced in mammary carcinoma cells functions as a promoter of tumor angiogenesis. Forced expression of TFF3 in mammary carcinoma cells promoted proliferation, survival, invasion and in vitro tubule formation of human umbilical vein endothelial cells (HUVEC). MCF7-TFF3 cells with forced expression of TFF3 generated tumors with enhanced microvessel density as compared to tumors formed by vector control cells. Depletion of TFF3 in mammary carcinoma cells by siRNA concordantly decreased the angiogenic behavior of HUVEC. Forced expression of TFF3 in mammary carcinoma cells stimulated IL-8 transcription and subsequently enhanced IL-8 expression in both mammary carcinoma cells and HUVEC. Depletion of IL-8 in mammary carcinoma cells with forced expression of TFF3, or antibody inhibition of IL-8, partially abrogated mammary carcinoma cell TFF3-stimulated HUVEC angiogenic behavior in vitro, as did inhibition of the IL-8 receptor, CXCR2. Depletion of STAT3 by siRNA in MCF-7 cells with forced expression of TFF3 partially diminished the angiogenic capability of TFF3 on stimulation of cellular processes of HUVEC. Exogenous recombinant hTFF3 also directly promoted the angiogenic behavior of HUVEC. Hence, TFF3 is a potent angiogenic factor and functions as a promoter of de novo angiogenesis in mammary carcinoma, which may co-coordinate with the growth promoting and metastatic actions of TFF3 in mammary carcinoma to enhance tumor progression.

Trefoil factor 3 (TFF3) enhances the oncogenic characteristics of prostate carcinoma cells and reduces sensitivity to ionising radiation

Trefoil factor 3 (TFF3) is a secreted protein which functions in mucosal repair of the gastrointestinal tract. This is achieved through the combined stimulation of cell migration and prevention of apoptosis and anoikis, thus facilitating repair. Deregulated TFF3 expression at the gene and protein level is implicated in numerous cancers. In prostate cancer TFF3 has previously been reported as a potential biomarker, overexpressed in a subset of primary and metastatic cases. Here we investigated the effect of increased TFF3 expression on prostate cancer cell behaviour. Oncomine analysis demonstrated that TFF3 mRNA expression was upregulated in prostate cancer compared to normal tissue. Forced-expression models were established in the prostate cancer cell lines, DU145 and PC3, by stable transfection of an expression vector containing the TFF3 cDNA. Forced expression of TFF3 significantly increased total cell number and cell viability, cell proliferation and cell survival. In addition, TFF3 enhanced anchorage independent growth, 3-dimensional colony formation, wound healing and cell migration compared to control transfected cell lines. We also observed reduced sensitivity to ionising radiation in stably transfected cell lines. In dose response experiments, forced expression of TFF3 significantly enhanced the regrowth of PC3 cells following ionising radiation compared with control transfected cells. In addition, TFF3 enhanced clonogenic survival of DU145 and PC3 cells. These studies indicate that targeting TFF3 for the treatment of prostate cancer warrants further investigation.

Trefoil factor 3 promotes metastatic seeding and predicts poor survival outcome of patients with mammary carcinoma

Introduction

Recurrence or early metastasis remains the predominant cause of mortality in patients with estrogen receptor positive (ER+) mammary carcinoma (MC). However, the molecular mechanisms underlying the initial progression of ER+ MC to metastasis remains poorly understood. Trefoil factor 3 (TFF3) is an estrogen-responsive oncogene in MC. Herein, we provide evidence for a functional role of TFF3 in metastatic progression of ER+ MC.

Methods

The association of TFF3 expression with clinicopathological parameters and survival outcome in a cohort of MC patients was assessed by immunohistochemistry. The expression of TFF3 in MCF7 and T47D cells was modulated by forced expression or siRNA-mediated depletion of TFF3. mRNA and protein levels were determined using qPCR and western blot. The functional effect of modulation of TFF3 expression in MC cells was determined in vitro and in vivo. Mechanistic analyses were performed using reporter constructs, modulation of signal transducer and activator of transcription 3 (STAT3) expression, and pharmacological inhibitors against c-SRC and STAT3 activity.

Results

TFF3 protein expression was positively associated with larger tumour size, lymph node metastasis, higher stage, and poor survival outcome. Forced expression of TFF3 in ER+ MC cells stimulated colony scattering, cell adhesion to a Collagen I-coated matrix, colony formation on a Collagen I- or Matrigel-coated matrix, endothelial cell adhesion, and transmigration through an endothelial cell barrier. In vivo, forced expression of TFF3 in MCF7 cells stimulated the formation of metastatic nodules in animal lungs. TFF3 regulation of the mRNA levels of epithelial, mesenchymal, and metastatic-related genes in ER+ MC cells were consistent with the altered cell behaviour. Forced expression of TFF3 in ER+ MC cells stimulated phosphorylation of c-SRC that subsequently increased STAT3 activity, which lead to the downregulation of E-cadherin. siRNA-mediated depletion of TFF3 reduced the invasiveness of ER+ MC cells.

Conclusions

TFF3 expression predicts metastasis and poor survival outcome of patients with MC and functionally stimulates cellular invasion and metastasis of ER+ MC cells. Adjuvant functional inhibition of TFF3 may therefore be considered to ameliorate outcome of ER+ MC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0429-3) contains supplementary material, which is available to authorized users.

Prognostic significance of the co-expression of nucleophosmin and trefoil factor 3 in postoperative gastric cancer patients

Although a number of studies have indicated that the positive expression of nucleophosmin (NPM) and trefoil factor 3 (TFF3) is associated with oncogenesis and poor prognosis in several tumor types, the prognostic value of the co-expression of NPM and TFF3 in gastric cancer (GC) has not been fully elucidated. Therefore, in this study, we aimed to investigate the role of NPM and TFF3 in GC and determine their prognostic value. We retrospectively reviewed 108 patients who had undergone radical gastric tumor resection. The expression of NPM and TFF3 was detected by immunohistochemistry and the association of NPM and TFF3 with clinicopathological characteristics was investigated using the Chi-square test. Furthermore, univariate and multivariate analyses were conducted to determine the prognostic value of these markers. Of the 108 samples, NPM was positive in 57 (53%) and TFF3 was positive in 54 samples (50%). The positive expression of NPM was correlated with advanced tumor stage and recurrence (P=0.0333 and P<0.0001, respectively), whereas the expression of TFF3 was associated with larger tumor size (P=0.0005), poor differentiation (P=0.0435), lymph node metastasis (P=0.0116), advanced tumor stage (P=0.0244) and recurrence (P=0.0116). The univariate analysis revealed that the expression of NPM, the expression of TFF3 and the co-expression of the two were associated with poor survival (P=0.0004, 0.0028 and 0.0020, respectively). By multivariate analysis, all three factors were identified as independent prognostic factors in postoperative GC patients (hazard ratio = 1.970, 2.021 and 2.339, respectively). In conclusion, the expression of NPM and TFF3 and, particularly, the co-expression of the two, may serve as independent prognostic factors in postoperative GC patients.

Kinetic characterization of an intestinal trefoil factor receptor

Objective

To determine whether intestinal epithelial cells have a receptor for intestinal trefoil factor and characterize receptor-ligand binding kinetics.

Methods

Radioligand binding assays were performed to characterize the binding kinetics between [¹²⁵I]-labeled ITF and IEC-6, HT-29, Caco2 and HaCaT cells. The K_d, B_max and other kinetic variables describing the interaction between ITF and its potential receptors were determined.

Results

Radioligand binding assays performed at 4°C showed that the K_d value for the association between [¹²⁵I]-ITF and IEC-6, HT-29, and Caco2 cells were 1.99±0.12×10⁻⁹ M, 3.89±0.42×10⁻⁹ M, and 2.04±0.17×10⁻⁹ M, respectively. B_max values were 1.17±0.04×10¹¹, 3.97±0.29×10¹¹, and 2.03±0.08×10¹¹ sites/cell, respectively. The K_i values for the interaction between IEC-6, HT-29, and Caco2 cells and non-labeled ITF were 20.98±0.57 nM, 36.87±3.35 nM, and 21.38±0.93 nM, respectively, and the IC₅₀ values were 25.21±0.39 nM, 40.68±0.27 nM, and 23.61±0.25 nM, respectively. Radioligand binding kinetic results showed the association rate constants (k₊₁) for IEC-6, HT-29, and Caco2 cells were 0.22±0.04 min⁻¹, 0.29±0.04 min⁻¹, and 0.26±0.05 min⁻¹, respectively, and the dissociation rate constants (k_-1) were 0.06±0.02 min⁻¹, 0.03±0.01 min⁻¹, and 0.04±0.01 min⁻¹, respectively. For the HaCaT cells, the K_d was 4.86±0.28×10⁻⁸ M and B_max was 5.81±0.15×10⁸ sites/cell, the very low specific binding between [¹²⁵I]-ITF and these cells made it impossible to calculate binding kinetic parameters.

Conclusions

An ITF-specific receptor appears to be present on the three types of intestinal epithelial cells (IEC-6, HT-29, and Caco-2), and there may be no ITF receptor on epidermal cells.

Trefoil factor 1 suppression of E-CADHERIN enhances prostate carcinoma cell invasiveness and metastasis

Metastasis is the primary mediator of prostate cancer (PCA) lethality and poses a significant clinical obstacle. The identification of factors involved in the metastasis of PCA is imperative. We demonstrate herein that trefoil factor 1 (TFF1) promotes PCA cell migration and invasion in vitro and metastasis in vivo. The capacity of TFF1 to enhance cell migration/invasion is mediated by transcriptional repression of E-CADHERIN. Consideration of targeted inhibition of TFF1 to prevent metastasis of prostate carcinoma is warranted.

Regulatory function of trefoil peptides (TFF) on intestinal cell junctional complexes

Abstract Trefoil peptides (TFF) are constitutively expressed in the gastrointestinal tract and are involved in gastrointestinal defence and repair by promoting epithelial restitution. Although there is a general consensus regarding the pro-motogenic activity of trefoil peptides, the cellular mechanisms through which they mediate these processes are not completely understood. Pertubation of the E-cadherin/catenin complex at intercellular junctions appears to be a functional pathway through which TFF2 and TFF3 promote cell migration. Tight junction complexes seal the paracellular spaces between cells and contribute to epithelial barrier function. TFF3 peptide stimulation stabilises these junctions through upregulation of the tightening protein claudin-1 and redistribution of ZO-1 from the cytoplasm to the intercellular membrane with an increase in binding to occludin. Modulation of the functional activity and subcellular localisation of epithelial junctional adhesion molecules represent important mechanisms by which trefoil peptides may promote migration of intestinal epithelial cells in vitro and healing of mucosal damage in vivo.

Putative tumor metastasis-associated genes in human gastric cancer

Gastric cancer is one of the leading causes of cancer mortality and its malignancy, resulting from disseminated cancer cells of diffuse type, is clinically manifested as metastases to the liver and peritoneum. The aim of the present study was to identify putative tumor metastasis-associated genes in human gastric cancer cells of diffuse type. An MKN45 cell line constitutively expressing green fluorescent protein (MKN45-GFP) was established and selected using the Transwell® system for invasive sublines MKN45-GFP-4, MKN45-GFP-10 and MKN45-GFP-12. MKN45-GFP-10 and MKN45-GFP-12 are highly invasive compared to the others. The mRNA levels were measured with cDNA microarrays and correlated with their invasion abilities in these sublines. Many of the genes identified with a positive or negative correlation are associated with angiogenesis, cell cycle, cytoskeleton and cell motility, protease and cell adhesion, as well as cellular signal transduction. In particular, novel genes without known functions were also noted. RT-PCR and western blot analyses were applied to verify the expression of selective genes. Following orthotopical intraperitoneal implantation, MKN45-GFP-12 demonstrated significantly higher in vivo tumor malignancies than parental MKN45-GFP in ascites induction and liver -invasion in mice. We have identified putative gastric tumor metastasis-associated, as well as novel genes. These genes and their protein products are to be further explored for their functional roles associated with tumor metastasis. The molecular profiles of these identified genes, gene transcripts and proteins in the patient specimens are likely to be useful biomarkers for diagnostic, therapeutic and/or prognostics. Most importantly, they may be used as molecular targets for the discovery of antitumor drugs against human gastric cancer metastasis.

TFF3 mediated induction of VEGF via hypoxia in human gastric cancer SGC-7901 cells

Increasing evidence indicates that in gastric epithelial cells, induction of TFF3 by hypoxia is mediated by HIF-1. Since VEGF is one of the most important angiogenic factors on cancer progression, we have started to investigate the possible link among HIF-1α, VEGF, and TFF3 in gastric cancer cells. We induced the hypoxic condition in SGC-7901cells using hypoxia-mimetic agent of CoCI2. SGC7901 cells were transfected with pcPUR + U6 plasmid carrying RNAi targeted to human TFF3 and selected puromycin-resistant pools to establish the stable knockdown of TFF3 cells. Our results showed the induction of HIF-1a via hypoxia and consequences of increased expressions of the TFF3 and VEGF in gastric cancer SGC-7901 cells. Overexpression of TFF3 upregulated the mRNA expressions of VEGF and HIF-1a induced by hypoxia, and stable knockdown of TFF3 impaired the mRNA upregulations of VEGF and HIF-1a induced by hypoxia. Furthermore, knockdown of TFF3 reduced the VEGF protein secretion: as VEGF secretion was increased time dependent manner in response to the hypoxia induction in TFF3-WT cells; however, VEGF production was significantly decreased in TFF3-KD cells (621 ± 89 vs. 264 ± 73 at 6 h and 969 ± 97 vs. 508 ± 69 at 12 h, P < 0.05). Our data demonstrated the TFF3 mediated regulation of VEGF expression induced by hypoxia, and implicated that TFF3 might be applied as a potential anti-angiogenic target for treatment of gastric cancer.

Expression of trefoil factor family-3 and β-catenin in different types of colorectal mucosal lesions

AIM: To analyze the expression of trefoil factor family-3 (TFF3) and β-catenin in different types of colorectal mucosal lesions and to explore their role in the development and progression of colorectal adenocarcinoma and adenoma.

METHODS: The expression of TFF3 and β-catenin was detected by immunohistochemistry in 20 normal colorectal mucosa specimens, 30 colorectal polyp specimens, 20 colorectal adenoma (CRA) specimens, 20 colorectal adenoma (with atypical hyperplasia, CRAAH) specimens, and 40 colorectal adenocarcinoma (CRCA) specimens. The differences in the expression of TFF3 and β-catenin in different types of colorectal mucosal lesions were compared.

RESULTS: The positive rate of TFF3 expression was significantly lower in CRA and CRAAH (P < 0.05), but higher in CRCA. The abnormal expression of β-catenin were gradually increasing along with the sequence of CRA→CRAAH→CRAC, the membrane expressing deletion and ectopic expression were both higher in CRAC than in CRCP and CRA (60.00% vs 0.00%, 15.00%; 75.00% vs 0.00%, 40.00%, all P < 0.05). TFF3 expression was not correlated with tumor location or differentiation in CRAC, but was related to lymph node metastasis and Duke's stage (both P < 0.05). β-catenin expression was not correlated with tumor location or lymph node metastasis, but was related to tumor differentiation. Ectopic expression of β-catenin was related to Duke's stage (P < 0.05). There were significantly positive correlations between TFF3 expression and abnormal expression and loss of membrane expression of β-catenin in CRA (r = 0.427, P = 0.006; r = 0.577, P = 0.000) but not in CRAC (r = 0.015, P = 0.951; r = 0.385, P = 0.094). There was a significantly positive correlation between loss of membrane expression and ectopic expression of β-catenin in CRAC and CRA (r = 0.638, P = 0.000; r = 0.514, P = 0.020).

CONCLUSION: The expression of TFF3 and β-catenin is closely related with the development and progression of CRAC. They may be involved in an early event in colorectal carcinogenesis. TFF3 is related to the abnormal expression of β-catenin, both of which may be involved in the development and progression of CRAC.

Norovirus non-structural protein p20 leads to impaired restitution of epithelial defects by inhibition of actin cytoskeleton remodelling

OBJECTIVE

Norovirus is the most common cause of acute gastroenteritis in humans worldwide. Typical symptoms are vomiting, nausea and severe watery diarrhea. Because of the lack of cell lines susceptible to human norovirus infection, pathomechanisms and replication cycle are largely unknown. Here, we address the issue of how norovirus infection could lead to epithelial barrier dysfunction.

MATERIAL AND METHODS

Expression of the non-structural norovirus protein p20 in the epithelial cell line HT-29/B6 was activated through a tetracycline sensitive promoter. Tight junction proteins were studied by Western blot and confocal laser scanning microscopy. Apoptoses were detected in TUNEL stainings. Epithelial restitution was monitored by conductance scanning after induction of single cell lesions.

RESULTS

Changes in the expression or localization of the tight junction proteins occludin and/or claudin-1, -2,- 3, -4, -5, -7 and -8 could be ruled out to mediate epithelial barrier modulation. Cell motility was also unaltered by p20. Investigation of epithelial apoptosis revealed an accumulation of apoptic cells in epithelial monolayers after induction of p20 expression. In epithelial cell restitution assays, an arrest was identified in p20 expressing cells. Fluorescence microscopy revealed an inability for condensation and redistribution of cellular actin, which led to a reduced transepithelial electrical resistance.

CONCLUSIONS

Functional data for norovirus protein p20 suggest a role in modulation of the actin cytoskeleton leading to barrier dysfunction through impairment of restitution of epithelial defects.

Advance in relationship between TFF3 and gastric cancer

Trefoil factor family (TFF) consists of three members, including TFF1, TFF2 and TFF3. TFF has such functions as maintaining gut mucosal integrity, promoting epithelial cell restitution, as well as cell signal transduction, modulating apoptosis and enhancing invasion. Therefore, TFF plays crucial roles in the process of inflammation and tumorigenesis. Researches recently have indicated that TFF3 plays an important role in gastric cancer, especially in intestinal gastric carcinoma.

Advances in research of trefoil factor 3

As one of important defensive factors, trefoil factor 3 (TFF3) has considerable relation to the lesion, recovery, proliferation and malignancy of gastrointestinal mucosa. Furthermore, the correlation between TFF3 and tumor, including its pathogenesis, progress and prognosis, has been reported remarkably. However, the binding proteins of TFF3 remains to be confirmed and the research of TFF3 on the mechanism of action and signal transduction pathway is just initial. This article reviewed the progress in TFF3 research.

Cadherins in development and cancer

Proper embryonic development is guaranteed under conditions of regulated cell-cell and cell-matrix adhesion. The cells of an embryo have to be able to distinguish their neighbours as being alike or different. Cadherins, single-pass transmembrane, Ca(2+)-dependent adhesion molecules that mainly interact in a homophilic manner, are major contributors to cell-cell adhesion. Cadherins play pivotal roles in important morphogenetic and differentiation processes during development, and in maintaining tissue integrity and homeostasis. Changes in cadherin expression throughout development enable differentiation and the formation of various organs. In addition to these functions, cadherins have strong implications in tumourigenesis, since frequently tumour cells show deregulated cadherin expression and inappropriate switching among family members. In this review, I focus on E- and N-cadherin, giving an overview of their structure, cellular function, importance during development, role in cancer, and of the complexity of Ecadherin gene regulation.

Phage display screening of epithelial cell monolayers treated with EGTA: identification of peptide FDFWITP that modulates tight junction activity

Phage display was used to screen for peptides that modulate the activity of epithelial cell tight junctions. Panning with a phage library that displays random 7-mers was performed using monolayers of human bronchial epithelial cells (16HBE14o(-)) treated with a calcium chelator, ethylene glycol-bis(2-aminoethylether)- N, N, N', N'-tetraacetic acid (EGTA), to increase accessibility to the junctional complex/paracellular space, followed by subtractive panning. A novel peptide, FDFWITP, identified as a potential tight junction modulator, was synthesized in linear and cyclic forms with lysine residues added to improve solubility. The cyclic form of the peptide reduced transepithelial electrical resistance (TER) in a concentration-dependent manner (80% reduction at 100 microM and 95% reduction at 500 microM) and was reversible within 2 h; the linear form only affected TER at the highest concentration. Interestingly, the constrained peptide did not increase permeation of the model small molecule, fluorescein. The highly selective activity of FDFWITP supports the hypothesis that ions and small molecules may be transported paracellularly across tight junctions by separate pathways.

TFF3 and EGF induce different migration patterns of intestinal epithelial cells in vitro and trigger increased internalization of E-cadherin

BACKGROUND/AIMS

TFF3, a member of the TFF (trefoil factor family) peptides, and epidermal growth factor (EGF) actively support the repair of mucosal barriers, particularly during restitution. The aim of this study was to compare the motogenic effects of TFF3 and EGF.

METHODS

The influence of recombinant human TFF3 (dimeric form) and EGF on the migration of IEC-18 cells was characterized in an in vitro restitution model (scratch wound assay) with the help of time-lapse video microscopy, morphometry, and immunocytochemistry including confocal laser scanning microscopy.

RESULTS

TFF3- and EGF-treated cells re-populated the wounded area via different migration patterns; TFF3 treatment resulted in the formation of continuous sheets of migrating cells with only a few gaps. In contrast, EGF-treated cells formed a network of migrating cells (often with a fibroblast-like morphology) with numerous gaps and only punctual contacts. TFF3 and EGF treatment also changed the localization of E-cadherin indicating endocytotic recycling and/or degradation of E-cadherin.

CONCLUSION

TFF3, in contrast to EGF, enhanced a collective cell migration ensuring a precise coverage of the re-populated area avoiding gaps.

The connexin turnover, an important modulating factor of the level of cell-to-cell junctional communication: comparison with other integral membrane proteins

The constituent proteins of gap junctions, called "connexins" (Cxs) in chordates, are generally renewed several times a day, in approximately the same rate range as many other integral plasma membrane proteins and the proteins of other channels, other intercellular junctions or different membrane receptors. This permanent renewal turns on a fine-tuned balance among various processes, such as gene transcription, mRNA stability and processing, protein synthesis and oligomerization, posttranslational modifications, transport to the plasma membrane, anchoring to the cytoskeleton, connexon aggregation and docking, regulation of endocytosis and controlled degradations of the proteins. Subtle changes at one or some of these steps would represent an exquisite level of regulation that extends beyond the rapid channel opening and closure events associated with channel gating; membrane channels and receptors are constantly able to answer to physiological requirements to either up- or downregulate their activity. The Cx turnover rate thereby appears to be a key component in the regulation of any protein, particularly of gap junctional proteins. However, the physiological stimuli that control the assembly of Cxs into gap junctions and their degradation remain poorly understood.

TFF3-peptide increases transepithelial resistance in epithelial cells by modulating claudin-1 and -2 expression

TFF3 plays an important role in the protection and repair of the gastrointestinal mucosa. The molecular mechanisms of TFF function, however, are still largely unknown. Increasing evidence indicates that apart from stabilizing mucosal mucins TFF3 induces cellular signals that modulate cell-cell junctions of epithelia. In transfected HT29/B6 and MDCK cells stably expressing FLAG-tagged human TFF3 we have recently shown that TFF3 down-regulates E-cadherin, impairs the function of adherens junctions and thus facilitates cell migration in wounded epithelial cell layers. Here we investigate TFF3-induced effects on the composition and function of tight junctions in these cells. TFF3 increased the cellular level of tightening claudin-1 and decreased the amount of claudin-2 known to form cation-selective channels. Expression of ZO-1, ZO-2 and occludin was not altered. The change in claudin-1 and -2 expression in TFF3-expressing HT29/B6 cells was accompanied by an increase in the transepithelial resistance in confluent monolayers of these cells. These data suggest that TFF3 plays a role in the regulation of intestinal barrier function by altering the claudin composition within tight junctions thus decreasing paracellular permeability of the intestinal mucosa.

Expression of intestinal trefoil factor (TFF-3) in hepatocellular carcinoma

BACKGROUND

Trefoil peptides (TFF-1, 2, 3) are a family of protease-resistant regulatory factors that play a role in mucosal restitution, angiogenesis, apoptosis, and tumor progression. Intestinal trefoil peptide (TFF-3) expression has been demonstrated in benign hepatobiliary diseases, but there are limited data regarding its expression in HCC.

METHODS

Thirty consecutive cases of HCC from 1998 to 2003 were studied. Immunohistochemistry was performed on formalin-fixed paraffin-embedded blocks of HCC using polyclonal antibody to TFF-3. TFF-3 expression was classified as strong, moderate, weak, focal, and negative. Clinical data were obtained per an IRB-approved protocol.

RESULTS

Median age was 69 yr (range: 39-83 yr). Twenty- three patients were males and 7 were females. Treatments included hepatic resection (n = 16), chemo-embolization (n = 4), combined modality therapy (n = 5) and no treatment (n = 4). HCC was well differentiated in 12 (40%), moderately differentiated in 13 (43%), and poorly differentiated in 5 (17%) patients. TFF-3 expression was detected in 28/30 (93.3%) patient samples. Sixteen patients (53%) had moderate and 1 (3%) patient had strong TFF-3 expression. Tumor/ normal tissue interface was assessable in 21 cases; 11 cases expressed TFF-3 at the interface. There was a strong correlation between tumor grade and TFF-3 expression, wherein poorly differentiated tumors had moderate/strong TFF-3 expression (p = 0.008). There was no correlation between TFF-3 expression and survival (p = 0.77). Furthermore, there was no correlation among age, disease stage, and survival.

CONCLUSION

TFF-3 is commonly expressed in HCC and its expression correlates with tumor grade.

Intestinal trefoil factor promotes invasion in non-tumorigenic Rat-2 fibroblast cell

Intestinal trefoil factor (TFF3) is essential in regulating cell migration and maintaining mucosal integrity in gastrointestinal tract. We previously showed that TFF3 was overexpressed in gastric carcinoma. Whether TFF3 possesses malignant potential is not fully elucidated. We sought to investigate the effects of inducting TFF3 expression in a non-malignant rat fibroblast cell line (Rat-2) on the cell proliferation, invasion and the genes regulating cell invasion. Invasiveness and proliferation of transfected Rat-2 cell line were assessed using in vitro invasion chamber assay and colorimetric MTS assay. Differential mRNA expressions of invasion-related genes, namely, metalloproteinases (MMP-9), tissue inhibitors of metalloproteinases (TIMP-1), beta-catenin and E-cadherin, were determined by quantitative real-time polymerase chain reaction (PCR). We showed that TFF3 did not inhibit the proliferation of Rat-2 cells. We also demonstrated that transfection of TFF3 significantly promoted invasion of Rat-2 cells by 1.4- to 2.2-folds. There was an upregulation of beta-catenin (13.1-23.0%) and MMP-9 (43.4-92.2%) mRNA expression levels, and downregulation of E-cadherin (25.6-33.8%) and TIMP-1 (31.5-37.8%) in TFF3-transfected cells compared to controls during 48-h incubation. Our results suggested that TFF3 possesses malignant potential through promotion of cell invasiveness and alteration of invasion-related genes.