Somatic mutations of the trefoil factor family 1 gene in gastric cancer

Gastric Inhibitory Polypeptide Receptor (GIPR) Overexpression Reduces the Tumorigenic Potential of Retinoblastoma Cells

Retinoblastoma (RB) is the most common malignant intraocular tumor in early childhood. Gene expression profiling revealed that the gastric inhibitory polypeptide receptor (GIPR) is upregulated following trefoil factor family peptide 1 (TFF1) overexpression in RB cells. In the study presented, we found this G protein-coupled transmembrane receptor to be co-expressed with TFF1, a new diagnostic and prognostic RB biomarker for advanced subtype 2 RBs. Functional analyses in two RB cell lines revealed a significant reduction in cell viability and growth and a concomitant increase in apoptosis following stable, lentiviral GIPR overexpression, matching the effects seen after TFF1 overexpression. In chicken chorioallantoic membrane (CAM) assays, GIPR-overexpressing RB cells developed significantly smaller CAM tumors. The effect of GIPR overexpression in RB cells was reversed by the GIPR inhibitor MK0893. The administration of recombinant TFF1 did not augment GIPR overexpression effects, suggesting that GIPR does not serve as a TFF1 receptor. Investigations of potential GIPR up- and downstream mediators suggest the involvement of miR-542-5p and p53 in GIPR signaling. Our results indicate a tumor suppressor role of GIPR in RB, suggesting its pathway as a new potential target for future retinoblastoma therapy.

Downregulation of the Tumor Suppressor TFF1 Is Required during Induction of Colon Cancer Progression by L1

Simple Summary

Aberrant activation of Wnt/β-catenin signaling and the subsequent induction of downstream target genes is a hallmark of colorectal cancer (CRC) development. Previously, we found that overexpression of the immunoglobulin-like cell adhesion receptor L1CAM (L1), a target of the Wnt/β-catenin pathway, confers enhanced proliferation, motility, tumorigenesis, and liver metastasis in CRC cells. Transcriptomic and proteomic analyses revealed changes in both pro-tumorigenic and potential tumor-suppressor genes in L1-overexpressing CRC cells. We wished to identify such tumor suppressor/s, and found that trefoil family factor 1 (TFF1) was involved in L1-mediated CRC progression. TFF1 overexpression suppressed the growth, motility and tumorigenesis of L1-expressing CRC cells by inhibiting the NF-κB pathway. In human CRC tissue, TFF1-positive staining was evident in goblet cells of the normal mucosa, while in CRC tissue, TFF1 expression was lost in >50% of the tumor samples. Our results support a tumor-suppressor role of TFF1 in human CRC, and we suggest that TFF1 could be used for CRC detection and as a novel therapeutic target in L1-mediated CRC.

Abstract

The immunoglobulin family cell adhesion receptor L1 is induced in CRC cells at the invasive front of the tumor tissue, and confers enhanced proliferation, motility, tumorigenesis, and liver metastasis. To identify putative tumor suppressors whose expression is downregulated in L1-expressing CRC cells, we blocked the L1–ezrin–NF-κB signaling pathway and searched for genes induced under these conditions. We found that TFF1, a protein involved in protecting the mucus epithelial layer of the colon, is downregulated in L1-expressing cells and displays characteristics of a tumor suppressor. Overexpression of TFF1 in L1-transfected human CRC cells blocks the pro-tumorigenic and metastatic properties conferred by L1 by suppressing NF-κB signaling. Immunohistochemical analyses revealed that human CRC tissue samples often lose the expression of TFF1, while the normal mucosa displays TFF1 in goblet cells. Identifying TFF1 as a tumor suppressor in CRC cells could provide a novel marker for L1-mediated CRC development and a potential target for therapy.

Relationships among microbiota, gastric cancer, and immunotherapy

Currently, conventional neoadjuvant therapy or postoperative adjuvant therapy, such as chemotherapy and radiation therapy, can only bring limited survival benefits to gastric cancer (GC). Median survival after palliative chemotherapy is also low, at about 8–10 months. Immunotargeting is a new option for the treatment of GC, but has not been widely replicated. The highly immunosuppressed tumor microenvironment (TME) discounts the efficacy of immunotherapy for GC. Therefore, new strategies are needed to enhance the immune response of the TME. This paper reviewed the relationship between microorganisms and GC, potential links between microorganisms and immunotherapy and research of microorganisms combined immunotherapy.

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.

The role of mechanosensitive Piezo1 channel in diseases

Mechanotransduction is associated with organ development and homoeostasis. Piezo1 and Piezo2 are novel mechanosensitive ion channels (MSCs) in mammals. MSCs are membrane proteins that are critical for the mechanotransduction of living cells. Current studies have demonstrated that the Piezo protein family not only functions in volume regulation, cellular migration, proliferation, and apoptosis but is also important for human diseases of various systems. The complete loss of Piezo1 and Piezo2 function is fatal in the embryonic period. This review summarizes the role of Piezo1 in diseases of different systems and perspectives potential treatments related to Piezo1 for these diseases.

C/EBPα Epigenetically Modulates TFF1 Expression via mC-6 Methylation in the Jejunum Inflammation Induced by a Porcine Coronavirus

Porcine epidemic diarrhea virus (PEDV) is an emerging coronavirus which causes acute diarrhea and destroys gastrointestinal barrier function in neonatal pigs. Trefoil factor 1 (TFF1) is a protective peptide for maintaining the integrity of gastrointestinal mucosa and reducing intestinal inflammation. However, its role in protecting intestinal epithelium against PEDV infection is still unclear. In this study, we discovered that TFF1 expression was activated in the jejunum of pigs with PEDV infection and TFF1 is required for the growth of porcine intestinal epithelial cells. For instance, inhibited cell proliferation and cell arrest were observed when TFF1 is genetically knocked-out using CRISPR-Cas9. Additionally, TFF1 depletion increased viral copy number and PEDV titer, along with the elevated genes involved in antiviral and inflammatory cytokines. The decreased TFF1 mRNA expression is in line with hypermethylation on the gene promoter. Notably, the strong interactions of protein-DNA complexes containing CCAAT motif significantly increased C/EBPα accessibility, whereas hypermethylation of mC-6 loci decreased C/EBPα binding occupancies in TFF1 promoter. Overall, our findings show that PEDV triggers the C/EBPα-mediated epigenetic regulation of TFF1 in intestine epithelium and facilitates host resistance to PEDV and other Coronavirus infections.

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.

Identification of stage-specific differentially expressed genes and SNPs in gastric cancer employing RNA-Seq based transcriptome profiling

We analysed over 400 million reads obtained from Illumina sequencing of six pairs of libraries representing two each of stage I, II, and III gastric tumors and corresponding normal tissues to identify differentially expressed genes (DEGs), single nucleotide polymorphisms (SNPs), and transcription factors (TFs). In total, 2207 DEGs including 972 upregulated genes and 1235 downregulated genes were detected. Of these, several stage-specific signature genes were identified. The protein-protein interaction networks involving DEGs and TFs were constructed. The KEGG pathway analysis of SNP harbouring genes revealed their involvement in different cancer related pathways like apoptosis, mTOR pathway, and MAPK signaling pathway. The SNP analysis showed implication of host genes in GO categories like immune system process, regulation of signaling, response to stress, and transport. A biased chromosomal distribution of DEGs and SNP harbouring genes was observed. Our study would provide further insights into the complex regulatory mechanisms operating during gastric tumorigenesis.

TFF-1 Functions to Suppress Multiple Phenotypes Associated with Lung Cancer Progression

Introduction

Trefoil Factor (TFF) is a member of a protein family comprised of three isoforms, of which TFF-1 exhibits antithetical functions; promotion or suppression of cell proliferation, survival and invasion, depending on the cancer type. However, the pathobiological function of TFF-1 in lung carcinoma has been still unclear.

Methods

We examined the expression and secretion of TFF-1 using cultured human lung carcinoma cells by immunoblotting, immunofluorescence, enzyme-linked immunosorbent assay and quantitative real-time PCR analyses. The effects of TFF-1 on various phenotypes were analyzed in two cell lines, including those transfected with cDNA encoding TFF-1. Cell proliferation and death were examined by hemocytometer cell counting and by colorimetric viability/cytotoxicity assay. Cell cycle profile, migration and invasion were also examined by flow cytometry, wound healing assay and Matrigel Transwell assay, respectively. The effect of TFF-1 overexpression was confirmed by additional transfection of TFF-1-specific siRNA.

Results

Endogenous TFF-1 protein expression and secretion into the media were observed exclusively in adenocarcinoma-derived cell lines. Forced overexpression of TFF-1 drove cell cycle transition, while the proliferation decreased by 19% to 25% due to increased cell death. This cell death was predominantly caused by apoptosis, as assessed by the activation of caspase 3/7. Cell migration was also suppressed by 71% to 82% in TFF-1-transfected cells. The suppressive effect of TFF-1 on proliferation and migration was restored by transfection of TFF-1 siRNA. Moreover, invasion was also suppressed to 77% to 83% in TFF-1-transfected cells.

Conclusion

These findings reveal that TFF-1 functions as a suppressor of cancer proliferation by induction of apoptosis, cell migration and invasion and thus may provide a synergistic target for potential treatment strategies for human lung carcinoma.

NF-kB-dependent activation of STAT3 by H. pylori is suppressed by TFF1

BACKGROUND

H. pylori infection is the main risk factor for gastric cancer. In this study, we investigated H. pylori-mediated activation of STAT3 and NF-κB in gastric cancer, using in vitro and in vivo models.

METHODS

To investigate the activation of NF-κB and STAT3 by H. pylori strains we used in vitro and in vivo mouse models, western blots, immunofluorescence, ChIP Assay, luciferase and quantitative real-time PCR assays.

RESULTS

Following infection with H. pylori in vitro, we found an earlier phosphorylation of NF-kB-p65 (S536), followed by STAT3 (Y705). Immunofluorescence, using in vitro and in vivo models, demonstrated nuclear localization of NF-kB and STAT3, following H. pylori infection. NF-kB and STAT3 luciferase reporter assays confirmed earlier activation of NF-kB followed by STAT3. In vitro and in vivo models demonstrated induction of mRNA expression of IL-6 (p < 0.001), VEGF-α (p < 0.05), IL-17 (p < 0.001), and IL-23 (p < 0.001). Using ChIP, we confirmed co-binding of both NF-kB-p65 and STAT3 on the IL6 promoter. The reconstitution of Trefoil Factor 1 (TFF1) suppressed activation of NF-kB with reduction in IL6 levels and STAT3 activity, in response to H. pylori infection. Using pharmacologic (BAY11-7082) and genetic (IκB super repressor (IκBSR)) inhibitors of NF-kB-p65, we confirmed the requirement of NF-kB-p65 for activation of STAT3, as measured by phosphorylation, transcription activity, and nuclear localization of STAT3 in in vitro and in vivo models.

CONCLUSION

Our findings suggest the presence of an early autocrine NF-kB-dependent activation of STAT3 in response to H. pylori infection. TFF1 acts as an anti-inflammatory guard against H. pylori-mediated activation of pro-inflammatory networks.

Trefoil Factor 1 Suppresses Epithelial-mesenchymal Transition through Inhibition of TGF-beta Signaling in Gastric Cancer Cells

Gastric cancer is a malignancy with high incidence and mortality worldwide. In gastric cancer, epithelial-mesenchymal transition (EMT) and metastasis further increase the mortality rate. Trefoil factor 1 (TFF1) has been reported as a protective factor in the gastric mucosa. In this study, TFF1 inhibited the migration and invasive capability of gastric cancer cells. Elevated TFF1 levels induced the expression of E-cadherin, the epithelial marker, and reduced the expression of N-cadherin, vimentin, Snail, Twist, Zinc finger E-box binding homeobox (ZEB) 1 and ZEB2, well-known repressors of E-cadherin expression. In addition, the expression of matrix metalloproteinase (MMP)-2, MMP-7 and MMP-9, which are major markers of cancer metastasis, was suppressed by TFF1. Upregulation of TFF1 inhibited TGF-β, a major signaling for EMT induction, and the phosphorylation of Smad2/3 activated by TGF-β in AGS cells. In conclusion, TFF1 inhibits EMT through suppression of TGF-β signaling in AGS cells, which might be used in therapeutic strategies for reducing metastatic potential and invasiveness of these cells.

Single-cell transcriptomes of pancreatic preinvasive lesions and cancer reveal acinar metaplastic cells' heterogeneity

Acinar metaplasia is an initial step in a series of events that can lead to pancreatic cancer. Here we perform single-cell RNA-sequencing of mouse pancreas during the progression from preinvasive stages to tumor formation. Using a reporter gene, we identify metaplastic cells that originated from acinar cells and express two transcription factors, Onecut2 and Foxq1. Further analyses of metaplastic acinar cell heterogeneity define six acinar metaplastic cell types and states, including stomach-specific cell types. Localization of metaplastic cell types and mixture of different metaplastic cell types in the same pre-malignant lesion is shown. Finally, single-cell transcriptome analyses of tumor-associated stromal, immune, endothelial and fibroblast cells identify signals that may support tumor development, as well as the recruitment and education of immune cells. Our findings are consistent with the early, premalignant formation of an immunosuppressive environment mediated by interactions between acinar metaplastic cells and other cells in the microenvironment.

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.

A functional polymorphism in TFF1 promoter is associated with the risk and prognosis of gastric cancer

Trefoil Factor 1 (TFF1, also named pS2), which serves as the gastrointestinal mucosal protector, is known as gastric-specific tumor suppressor gene. However, the genetic variants of TFF1 are still not well studied. In our study, we aim to explore the effects of tagging single nucleotide polymorphisms (tagSNPs) of TFF1 on risk and prognosis of gastric cancer. Seven tagSNPs of TFF1 gene were first analyzed in the discovery set, which was consisted of 753 cases and 950 cancer-free controls. Then, the validation set (940 cases and 1,042 controls) was used for further evaluation. Moreover, we also tested the relation between these tagSNPs and prognosis of gastric cancer (GC). A series of experiments were performed to investigate the underlying mechanisms. We found that rs3761376 AA in the promoter region of TFF1, could reduce the expression of TFF1 by affecting the binding affinity of estrogen receptor 1 (ESR1, ERα), and thereby increased the risk of GC (1.29, 1.08-1.53). Moreover, the rs3761376 AA genotype was also found associated with worse prognosis among patients receiving 5-FU based chemotherapy after surgery (1.71, 1.18-2.48). Further functional assays demonstrated that TFF1 could increase the chemosensitivity of 5-FU by modulating NF-κB targeted genes. These results identified the effect of rs3761376 on TFF1 expression, which accounted for the correlation with susceptibility and prognosis of GC; and this genetic variant may be a potential biomarker to predict the risk and survival of GC.

Gastric TFF1 Expression from Acute to Chronic Helicobacter Infection

TFF1, a mucin-associated secreted peptide of gastric mucous cells, is known as a protective agent for stomach epithelium under different stimuli, but its role upon Helicobacter infection is still not clear. In this paper we characterized TFFs expression, with particular attention to TFF1, under Helicobacter infection in gastric cell lines. A mouse model was used to distinguish TFF1 mRNA expression between acute and chronic stages of Helicobacter infection. Our results show that TFF1 expression is induced in infected cells; in addition, the inflammatory response upon Helicobacter infection is inversely associated to pre-existing TFF1 protein levels. In infected mice, TFF1 is initially upregulated in gastric antrum in the acute phase of infection, along with IL-1β and IL-6. Then, expression of TFF1 is gradually silenced when the infection becomes chronic and IFN-γ, CXCL5, and CXCL15 reach higher levels. Our data suggest that TFF1 might help cells to counteract bacteria colonization and the development of a chronic inflammation.

Heterodimeric interaction between GKN2 and TFF1 entails synergistic antiproliferative and pro-apoptotic effects on gastric cancer cells

BACKGROUND

GKN2 and TFF1 form a heterodimer that is only generated in the mucus-secreting cells of the normal stomach. The formation of this heterodimer is frequently disrupted in gastric cancer. However, the precise roles of GKN2 alone and in the heterodimer with TFF1 as well as the contributions of GKN2 and the heterodimer to gastric carcinogenesis are poorly understood.

METHODS

Cell viability, proliferation, and apoptosis were analyzed in AGS, MKN1, MKN28, and MKN45 gastric cancer cells transfected with GKN2 and/or TFF1 using MTT, BrdU incorporation, and apoptosis assays, respectively. In addition, cell viability was examined in HFE-145 non-neoplastic gastric epithelial cells after GKN2 and/or TFF1 silencing. Furthermore, the cell cycle and the expression of cell cycle and apoptosis related proteins were assessed. The interaction between GKN2 and TFF1 was confirmed by co-immunoprecipitation. Immunohistochemistry was employed to explore TFF1 expression in 169 gastric cancer tissues.

RESULTS

Co-transfection with GKN2 and TFF1 significantly inhibited cell viability and proliferation by inducing G1/S cell cycle arrest and suppressing positive cell cycle regulators. Simultaneous knockdown of GKN2 and TFF1 in HFE-145 cells resulted in markedly increased cell viability. Moreover, the interaction of GKN2 and TFF1 promoted cell death by enhancing caspase-3/7 activity and upregulating pro-apoptotic proteins. At the mRNA level, GKN2 and TFF1 were found to be positively correlated in non-tumor and tumor samples. Immunohistochemistry revealed loss of TFF1 expression in 128 (75.73%) of 169 gastric cancers. There was a borderline-significant association between GKN2 and TFF1 protein expression in gastric cancers (P = 0.0598).

CONCLUSION

Collectively, our data demonstrated that the interaction between GKN2 and TFF1 can have synergistic antiproliferative and pro-apoptotic effects on gastric cancer.

Loss of Tff1 Promotes Pro-Inflammatory Phenotype with Increase in the Levels of RORγt+ T Lymphocytes and Il-17 in Mouse Gastric Neoplasia

Background: TFF1 deficiency induces a mucosal pro-inflammatory phenotype that contributes to gastric tumorigenesis in mouse and human. Methods: We utilized the Tff1-KO mouse model to assess the impact of TFF1 loss on immune cells infiltration in the stomach. We used single cell suspension, flow cytometry, immunohistochemistry, and quantitative PCR (qPCR) assays. Results: The Tff1-KO gastric mucosa demonstrated high chronic inflammatory scores (score: 3-4) at age 2 months, which exacerbated at age 8 months (score: 4-6). We next used single-cell suspensions for flow cytometry analysis of total leukocytes (CD45+ cells), total T lymphocytes (CD45+CD3+cells), T cell subsets (CD4+, CD8+, and CD3+CD4-CD8-cells), and monocytes/macrophages (CD45+F4/80+cells). The results demonstrated an age-dependent (2 → 8 month age) significant increase of leukocytes (p<0.05), T cells (p<0.05), and monocytes/macrophages (p<0.001) in the gastric mucosa of the Tff1-KO mice, as compared to Tff1-WT. A similar increase was observed in blood samples (p<0.05). Using ionomycin to activate CD4⁺ splenocytes, the results indicated that Tff1-KO CD4⁺ splenocytes secreted higher levels of IL-17A (p<0.05 at 2 and p<0.001 at 8 months) and IL-17F (p<0.05 at 2 and 8 months) than Tff1-WT splenocytes. Conversely, Tff1-KO CD8⁺-cells secreted less IL-17F, but comparable levels of IL-17A. In addition, we detected a significant upregulation of Il-17 mRNA expression in gastric tissues in the Tff1-KO, as compared to Tff1-WT (p<0.001). Conclusions: The results identify TFF1 loss as a major pro-inflammatory step that modulates the tumor microenvironment and immune cell infiltration in the stomach. Furthermore, the data suggest that the increase of IL-17A and IL-17F in Th17 cells, derived from CD4⁺ T cells, reflects the chronic inflammation in gastric mucosa, whereas the absence of change of IL-17A and decrease of IL-17F in CD8⁺Tc17 cells suggest loss of cytotoxic function of CD8⁺Tc17 cells during gastric tumorigenesis of the Tff1-KO mice.

Wnt/β-catenin, an oncogenic pathway targeted by H. pylori in gastric carcinogenesis

A section of gastric cancers presents nuclear β-catenin accumulation correlated with H. pylori infection. H. pylori stimulate Wnt/β-catenin pathway by activating oncogenic c-Met and epidermal growth factor receptor (EGFR), or by inhibiting tumor suppressor Runx3 and Trefoil factor 1 (TFF1). H. pylori also trigger Wnt/β-catenin pathway by recruiting macrophages. Moreover, Wnt/β-catenin pathway is found involved in H. pylori-induced gastric cancer stem cell generation. Recently, by using gastroids, researchers have further revealed that H. pylori induce gastric epithelial cell proliferation through β-catenin. These findings indicate that Wnt/β-catenin is an oncogenic pathway activated by H. pylori. Therefore, this pathway is a potential therapy target for H. pylori-related gastric cancer.

NKX6.3 Is a Transcription Factor for Wnt/β-catenin and Rho-GTPase Signaling-Related Genes to Suppress Gastric Cancer Progression

Despite ongoing research and recent progress, the prognosis for patients with advanced gastric cancer remains poor. Wnt/β-catenin and Rho-GTPase signaling pathways are known to play essential roles in malignant transformation and progression of various tumors, including gastric cancer. Here, we identify that NKX6 transcription factor, locus 3 (NKX6.3) binds directly to specific promoter regions of Wnt/β-catenin and Rho-GTPase pathway-related genes, resulting in inhibition of cancer cell migration and invasion. Additionally, we find that the expression level of NKX6.3 is involved in regulation of gastric cancer progression and expression of Wnt/β-catenin and Rho-GTPase pathway-related genes in clinical samples. These results suggest that NKX6.3 prevents EMT and cell migration, implying that NKX6.3 inactivation might be one of the key mechanisms of gastric cancer cell invasion and metastasis.

Loss of TFF1 promotes Helicobacter pylori-induced β-catenin activation and gastric tumorigenesis

Using in vitro and in vivo models, we investigated the role of TFF1 in suppressing H. pylori-mediated activation of oncogenic β-catenin in gastric tumorigenesis. A reconstitution of TFF1 expression in gastric cancer cells decreased H. pylori-induced β-catenin nuclear translocation, as compared to control (p < 0.001). These cells exhibited significantly lower β-catenin transcriptional activity, measured by pTopFlash reporter, and induction of its target genes (CCND1 and c-MYC), as compared to control. Because of the role of AKT in regulating β-catenin, we performed Western blot analysis and demonstrated that TFF1 reconstitution abrogates H. pylori-induced p-AKT (Ser473), p-β-catenin (Ser552), c-MYC, and CCND1 protein levels. For in vivo validation, we utilized the Tff1-KO gastric neoplasm mouse model. Following infection with PMSS1 H. pylori strain, we detected an increase in the nuclear staining for β-catenin and Ki-67 with a significant induction in the levels of Ccnd1 and c-Myc in the stomach of the Tff1-KO, as compared to Tff1-WT mice (p < 0.05). Only 10% of uninfected Tff1-KO mice, as opposed to one-third of H. pylori-infected Tff1-KO mice, developed invasive adenocarcinoma (p = 0.03). These findings suggest that loss of TFF1 could be a critical step in promoting the H. pylori-mediated oncogenic activation of β-catenin and gastric tumorigenesis.

Inverse association between Bmi-1 and RKIP affecting clinical outcome of gastric cancer and revealing the potential molecular mechanisms underlying tumor metastasis and chemotherapy resistance

BACKGROUND

B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) and Raf kinase inhibitory protein (RKIP) are involved in cancer metastasis and chemotherapeutic resistance, respectively. In this study, we evaluated the association between Bmi-1 and RKIP and outcome of gastric cancer through clinical data analysis and in vitro experiments.

METHODS

Bmi-1 expression and RKIP expression were observed in 107 cases of gastric cancer through use of tissue microarray technology to identify their correlations with clinicopathological parameters, patient survival, and susceptibility to chemotherapy. The correlation was confirmed in gastric cancer cell lines, analyzed further by gene overexpression and silencing analysis, a cell invasion assay, and a chemosensitivity test.

RESULTS

Positive expression of Bmi-1 was highly correlated with T classification and clinical stage. Diminished or lost expression of RKIP was significantly associated with T classification, lymph node metastasis, distant metastasis, and clinical stage. Bmi-1 is negatively and RKIP is positively related to patient survival. Positive expression of Bmi-1 and negative expression of RKIP are associated with poor patient survival and modest efficacy of postoperative chemotherapy. A meaningfully inverse association between Bmi-1 and RKIP was found in tissue microarray studies, and was verified further in gastric cancer cell lines. Moreover, gene overexpression and silencing analysis indicated that RKIP might be regulated by Bmi-1. Furthermore, the impacts of Bmi-1 on cell invasion and chemotherapy resistance were rescued by knockdown of RKIP.

CONCLUSIONS

Our study implies that detection of Bmi-1 and RKIP is valuable in predicting patient survival and therapeutic response in gastric cancer, and the inverse association between Bmi-1 and RKIP reveals the potential molecular mechanisms underlying tumor metastasis and chemotherapy resistance.

Trefoil factor 1 expression suppresses Helicobacter pylori-induced inflammation in gastric carcinogenesis

BACKGROUND

Infection with Helicobacter pylori, a high-risk factor for gastric cancer, is frequently associated with chronic inflammation through activation of nuclear factor κB (NF-κB). Trefoil factor 1 (TFF1) is a constitutively expressed protein in the stomach that has tumor-suppressor functions and plays a critical role in maintaining mucosal integrity. This study investigated the role of TFF1 in regulating the proinflammatory response to H. pylori infections.

METHODS

For in vitro studies, immunofluorescence, luciferase reporter assays, Western blots, and quantitative real-time polymerase chain reaction were performed to investigate the activation of NF-κB and its target genes in response to infections with H. pylori strains J166 and 7.13. In addition, Tff1-knockout (KO) and Tff1-wild-type mice were used for infections with the H. pylori strain called premouse Sydney strain 1.

RESULTS

The reconstitution of TFF1 expression in gastric cancer cells significantly suppressed H. pylori-mediated increases in NF-κB-p65 nuclear staining, transcriptional activity, and expression of proinflammatory cytokine genes (tumor necrosis factor α, interleukin 1β, chemokine [C-X-C motif] ligand 5, and interleukin 4 receptor) that were associated with reductions in the expression and phosphorylation of NF-κB-p65 and IκB kinase α/β proteins. The in vivo studies using the Tff1-KO mouse model of gastric neoplasia confirmed the in vitro findings. Furthermore, they demonstrated increases in chronic inflammation scores and in the frequency of invasive gastric adenocarcinoma in the Tff1-KO mice infected with H. pylori versus the uninfected Tff1-KO mice.

CONCLUSIONS

These findings underscore an important protective role of TFF1 in abrogating H. pylori-mediated inflammation, a crucial hallmark of gastric tumorigenesis. Therefore, loss of TFF1 expression could be an important step in H. pylori-mediated gastric carcinogenesis.

Trefoils: An unexplored natural protective shield of oral cavity

The new mammalian growth factor peptide family consists of three peptides, TFF1, TFF2, and TFF3, which are secreted mainly from mucous epithelia with mucus gel. The predominant secretion of trefoil factor (TFF) occurs from gastric mucosal lining, small and large intestine, oral mucosal cells, and salivary glands. Research regarding trefoil factors is an immerging aspect in the dental field. The mucosal healing and restitution function describes about its novel role in case of chronic inflammatory conditions, but its expression from different tissue at different pathological condition shows its importance in immune response. At present, TFF expression has been detected from the severe periodontal diseased tissue samples. Future research from mild to moderate chronic periodontal diseased condition should be carried out to assess the protective response of TFF in gingival tissues. In future, assessment of TFF levels and its expression in oral mucosal tissues and oral secretions, such as saliva and gingival crevicular fluid, will provide a negative biomarker for chronic periodontal diseases and a novel therapeutic agent in oral mucosal healing.

STAT3 polymorphism and Helicobacter pylori CagA strains with higher number of EPIYA-C segments independently increase the risk of gastric cancer

Background

Because to date there is no available study on STAT3 polymorphism and gastric cancer in Western populations and taking into account that Helicobacter pylori CagA EPIYA-C segment deregulates SHP-2/ERK-JAK/STAT3 pathways, we evaluated whether the two variables are independently associated with gastric cancer.

Methods

We included 1048 subjects: H. pylori-positive patients with gastric carcinoma (n = 232) and with gastritis (n = 275) and 541 blood donors. Data were analyzed using logistic regression model.

Results

The rs744166 polymorphic G allele (p = 0.01; OR = 1.76; 95 % CI = 1.44-2.70), and CagA-positive (OR = 12.80; 95 % CI = 5.58-19.86) status were independently associated with gastric cancer in comparison with blood donors. The rs744166 polymorphism (p = 0.001; OR = 1.64; 95 % CI = 1.16-2.31) and infection with H. pylori CagA-positive strains possessing higher number of EPIYA-C segments (p = 0.001; OR = 2.28; 95 % CI = 1.41-3.68) were independently associated with gastric cancer in comparison with gastritis. The association was stronger when host and bacterium genotypes were combined (p < 0.001; OR = 3.01; 95 % CI = 2.29-3.98). When stimulated with LPS (lipopolysaccharide) or Pam3Cys, peripheral mononuclear cells of healthy carriers of the rs744166 GG and AG genotypes expressed higher levels of STAT3 mRNA than those carrying AA genotype (p = 0.04 for both). The nuclear expression of phosphorylated p-STAT3 protein was significantly higher in the antral gastric tissue of carriers of rs744166 GG genotype than in carriers of AG and AA genotypes.

Conclusions

Our study provides evidence that STAT3 rs744166 G allele and infection with CagA-positive H. pylori with higher number of EPIYA-C segments are independent risk factors for gastric cancer. The odds ratio of having gastric cancer was greater when bacterium and host high risk genotypes were combined.

Activation of β-catenin signalling by TFF1 loss promotes cell proliferation and gastric tumorigenesis

OBJECTIVE

In this study, we investigated the role of Trefoil factor 1 (TFF1) in regulating cell proliferation and tumour development through β-catenin signalling using in vivo and in vitro models of gastric tumorigenesis.

DESIGN

Tff1-knockout (Tff1-KO) mice, immunohistochemistry, luciferase reporter, qRT-PCR, immunoblot, and phosphatase assays were used to examine the role of TFF1 on β-catenin signalling pathway.

RESULTS

Nuclear localisation of β-catenin with transcriptional upregulation of its target genes, c-Myc and Ccnd1, was detected in hyperplastic tissue at an early age of 4-6 weeks and maintained during all stages of gastric tumorigenesis in the Tff1-KO mice. The reconstitution of TFF1 or TFF1 conditioned media significantly inhibited the β-catenin/T-cell factor (TCF) transcription activity in MKN28 gastric cancer cells. In agreement with these results, we detected a reduction in the levels of nuclear β-catenin with downregulation of c-MYC and CCND1 mRNA. Analysis of signalling molecules upstream of β-catenin revealed a decrease in phosphorylated glycogen synthase kinase 3β (p-GSK3β) (Ser9) and p-AKT (Ser473) protein levels following the reconstitution of TFF1 expression; this was consistent with the increase of p-β-catenin (Ser33/37/Thr41) and decrease of p-β-catenin (Ser552). This TFF1-induced reduction in phosphorylation of GSK3β, and AKT was dependent on protein phosphatase 2A (PP2A) activity. The treatment with okadaic acid or knockdown of PP2A abrogated these effects. Consistent with the mouse data, we observed loss of TFF1 and an increase in nuclear localisation of β-catenin in stages of human gastric tumorigenesis.

CONCLUSIONS

Our data indicate that loss of TFF1 promotes β-catenin activation and gastric tumorigenesis through regulation of PP2A, a major regulator of AKT-GSK3β signalling.

Trefoil factors (TFFs) are increased in bronchioalveolar lavage fluid from patients with chronic obstructive lung disease (COPD)

Trefoil factors (TFFs) 1, 2 and 3 are small polypeptides that are co-secreted with mucin throughout the body. They are up-regulated in cancer and inflammatory processes in the gastrointestinal system, where they are proposed to be involved in tissue regeneration, proliferation and protection. Our aim was to explore their presence in pulmonary secretions and to investigate whether they are up-regulated in pulmonary diseases characterized by mucin hypersecretion. Bronchioalveolar lavage fluid was obtained from 92 individuals referred to bronchoscopy. The patients were grouped according to diagnosis and pulmonary function. The concentrations of TFF1, TFF2 and TFF3 were measured by ELISA. All three peptides were detected in bronchioalveolar lavage fluid. Patients with chronic obstructive pulmonary disease had concentrations two to three times above the levels in the healthy reference group, and patients with pulmonary malignancies had concentrations of TFF1 and TFF2 three times that of the reference group. The results suggest that TFFs are involved in tissue regeneration, proliferation and protection in lung diseases.

Piezo1 is as a novel trefoil factor family 1 binding protein that promotes gastric cancer cell mobility in vitro

BACKGROUND

Trefoil factor family 1 (TFF1) is a member of the TFF-domain peptide family involved in epithelial restitution and cell motility. Recently, we screened Piezo1 as a candidate TFF1-binding protein.

AIM

We aimed to confirm Piezo1 as a novel TFF1 binding protein and to assess the role of this interaction in mediating gastric cancer cell mobility.

METHODS

This interaction was confirmed by co-immunoprecipitation and co-localisation of TFF1 and Piezo1 in GES-1 cells. We used stable RNA interference to knockdown Piezo1 protein expression and restored the expression of TFF1 in the gastric cancer cell lines SGC-7901 and BGC-823. Cell motility was evaluated using invasion assay and migration assay in vitro. The expression levels of the integrin subunits β1, β5, α1 as well as the expression of β-catenin and E-cadherin were detected by Western blot.

RESULTS

We demonstrate that TFF1, but not TFF2 or TFF3, bind to and co-localize with Piezo1 in the cytoplasm in vitro. TFF1 interacts with the C-terminal portion of the Piezo1 protein. Wound healing and trans-well assays demonstrated that the restored expression of TFF1 promoted cell mobility in gastric cancer cells, and this effect was attenuated by the knockdown of Piezo1. Western blots demonstrated the decreased expression of integrin β1 in Piezo1-knockdown cells.

CONCLUSIONS

Our data demonstrate that Piezo1 is a novel TFF1 binding protein that is important for TFF1-mediated cell migration and suggest that this interaction may be a therapeutic target in the invasion and metastasis of gastric cancer.

GKN2 contributes to the homeostasis of gastric mucosa by inhibiting GKN1 activity

Gastrokine 1 (GKN1) plays an important role in maintaining gastric mucosa integrity. Here, we investigated whether gastrokine 2 (GKN2) contributes to the homeostasis of gastric epithelial cells by regulating GKN1 activity. We analyzed cell viability, proliferation, and death in AGS cells transfected with GKN1, GKN2, GKN1 plus GKN2 using MTT, BrdU incorporation, and apoptosis assays, respectively. In addition, the expression levels of the cell cycle- and apoptosis-related proteins, miR-185, DNMT1, and EZH2 were determined. We also compared the expression of GKN1, GKN2, and CagA in 50 non-neoplastic gastric mucosae and measured GKN2 expression in 169 gastric cancers by immunohistochemistry. GKN2 inhibited anti-proliferative and pro-apoptotic activities, miR-185 induction, and anti-epigenetic modifications of GKN1. There was a positive correlation between GKN1 and GKN2 expression (P = 0.0074), and the expression of GKN1, but not GKN2, was significantly lower in Helicobacter pylori CagA-positive gastric mucosa (P = 0.0013). Interestingly, ectopic GKN1 expression in AGS cells increased GKN2 mRNA and protein expression in a time-dependent manner (P = 0.01). Loss of GKN2 expression was detected in 126 (74.6%) of 169 gastric cancers by immunohistochemical staining and was closely associated with GKN1 expression and differentiation of gastric cancer cells (P = 0.0002 and P = 0.0114, respectively). Overall, our data demonstrate that in the presence of GKN2, GKN1 loses its ability to decrease cell proliferation, induce apoptosis, and inhibit epigenetic alterations in gastric cancer cells. Thus, we conclude that GKN2 may contribute to the homeostasis of gastric epithelial cells by inhibiting GKN1 activity.

miRNA423-5p regulates cell proliferation and invasion by targeting trefoil factor 1 in gastric cancer cells

TFF1 is a small, secreted protein in the TFF family that has a pivotal role as a motogenic factor in epithelial restitution and cell motility, and as a tumor suppressor gene in the stomach. In this study, we identified TFF1 as a novel target gene of miRNA-423-5p. miRNA-423-5p negatively regulated the expression of TFF1 by binding to its 3'UTR and participated in proliferation/invasion-related processes via a TFF1-dependent manner in gastric cancer cells. Our findings suggested that miR-423-5p may be a novel target for the future development of specific therapeutic interventions for gastric cancer.

Copper promotes TFF1-mediated Helicobacter pylori colonization

The trefoil peptides (TFF1, TFF2 and TFF3) are a family of small highly conserved proteins that play an essential role in epithelial regeneration within the gastrointestinal tract, where they are mainly expressed. TFF1 expression is strongly induced after mucosal injury and it has been proposed that tff1 functions as a gastric tumor suppressor gene. Several studies confirm that tff1 expression is frequently lost in gastric cancer because of deletions, mutations or methylation of the tff1 promoter. Infection by Helicobacter pylori (H. pylori) results in chronic gastritis and it can lead to the development of gastric or duodenal ulcers. Moreover, it is known that there is a strong link to the development of gastric cancer. It has been shown that H. pylori interacts with the dimeric form of TFF1 and that the rough form of lipopolysaccharide mediates this interaction. We have previously reported that the carboxy-terminus of TFF1 is able to specifically bind copper ions (Cu) and that Cu binding favours the homodimerization of the peptide, thus enhancing its motogenic activity. Here, we report that the Cu-TFF1 cuprocomplex promotes adherence of H. pylori to epithelial cells. Adherence of H. pylori to gastric adenocarcinoma cells, AGS AC1 cells, induced to hyper-express TFF1 was enhanced compared to noninduced cells. Copper further promoted this interaction. A H. pylori mutant unable to bind TFF1 did not show enhanced infection of induced cells. Cu treatment induced a thickening of the mucus layer produced by the colorectal adenocarcinoma mucus secreting, goblet cells, HT29-E12 and promoted H. pylori colonisation. Finally, SPR analysis shows that the C-terminus of TFF1, involved in the binding of copper, is also able to selectively bind H. pylori RF-LPS.

DNA methylation of trefoil factor 1 (TFF1) is associated with the tumorigenesis of gastric carcinoma

Trefoil factor 1 (TFF1) is a tumor suppressor gene that encodes a peptide belonging to the trefoil factor family of protease‑resistant peptides. Although TFF1 expression is frequently lost in gastric carcinomas (GCs), the tumorigenic pathways that are affected have yet to be determined. The aim of the current study was to identify the mechanism(s) by which the TFF1 gene is regulated in gastric carcinogenesis. In this study, TFF1 was shown to be silenced or downregulated in gastric tumor tissue compared with matched non‑cancerous tissue. In addition, human gastric cells weakly expressed TFF1. The hypermethylation status in the promoter CpG islands appeared to be correlated with TFF1 expression levels in gastric cell lines or specimen tissue. Further molecular analysis indicated that the CpG islands play a role in the promoter activity of the TFF1 gene. The expression of TFF1 and DNA methylation of its promoter affected cell proliferation and apoptosis. The expression of TFF1 in gastric cell lines was restored with a demethylating agent, 5‑azacytidine. Low expression of TFF1 in gastric cell lines and cancer tissue is associated with TP 53. In conclusion, the current study demonstrates that DNA methylation is a key mechanism of silencing TFF1 expression in human gastric cells and TFF1 gene hypermethylation of the CpG islands is a potential biomarker for GC.

Trefoil factor 1 gene alternations and expression in colorectal carcinomas

Aims and background

Aberrant expression of the trefoil factor family (TFF) has been recognized to be involved in the development and/or progression of various solid tumors. Increased trefoil factor 1 (TFF1) expression is found associated with tumor progression in some tumors, and TFF1 missense mutations have been detected in gastric cancer. The aim of the study was to analyze TFF1 alternations and expression in colorectal carcinoma and their correlation with cancer progression and pathological aspects.

Methods

TFF1 mutations were detected in colorectal carcinomas by DNA sequencing. TFF1mRNA and protein levels in subsets of the primary tumors were determined using quantitative reverse transcription polymerase chain reaction and immunohistochemistry analyses. The serum level of TFF1 was also detected by enzyme-linked immunosorbent assay for patients with colorectal carcinoma.

Results

Five variants were detected in the 5'-untranslation region and intron 1 of TFF1. TFF1 expression was increased in colorectal carcinoma compared to paired distal colonic mucosa. Immunohistochemistry in primary colorectal carcinoma showed no significant differences in tumor TFF1 levels with respect to clinicopathological parameters such as the patient's sex, cancer differentiation, stage and lymph node metastasis. However, serum TFF1 levels were significantly elevated in patients with colorectal carcinoma compared to healthy individuals.

Conclusions

The results indicate that TFF1 missense mutations seem to be a rare event in colorectal carcinogenesis. Serum TFF1 may be a potential useful marker for patients with colorectal carcinoma.

COX-2, TFF1, and Src define better prognosis in young patients with gastric cancer

BACKGROUND AND OBJECTIVES

Despite its dwindling occurrence, gastric cancer remains a leading cause of cancer related mortality worldwide. Molecular determinants of prognosis that impact survival are being sought out as a means to facilitate rational clinical decision-making and enhance patient management. In this study, we evaluated three molecules implicated in gastric carcinogenesis and demonstrated that the differential expression of cyclooxygenase-2 (COX-2) and the viral oncogene homolog Src proteins could explain the differences in survival observed in patients older and younger than 50 years of age.

METHODS

We evaluated 5-year survival in a cohort of 423 gastric cancer patients using chronological age as a variable. Additionally, we assessed the protein expression of three molecules (COX-2, TFF1, Src) implicated in the pathogenesis of gastric cancer using immunohistochemistry.

RESULTS

We found that patients younger than 50 years of age had a better 5-year survival rate in all tumor stages. We found that the expression of COX-2 and Src correlated significantly with survival in this group without any significant impact attributable to TFF1.

CONCLUSIONS

Our study demonstrates that young gastric cancer patients have a better prognostic outlook that could in part be explained by the differential expression of COX-2 and Src.

Activation of the NF-kB pathway downregulates TFF-1 in gastric carcinogenesis

Trefoil factor 1 (TFF1) is expressed in the normal superficial epithelium of the stomach and is implicated in the maintenance of gastric epithelial structure and function. During gastric carcinogenesis, in which pro-inflammatory cytokines play a crucial role, its expression level decreases suggesting a role as tumor suppressor factor. We have compared expression of TFF1 in gastric mucosa from cancer patients, in which several degrees of inflammatory infiltrate are present, with that in normal mucosa from non-cancer patients without infiltrating inflammatory cells. TFF1 is less expressed in the superficial gastric epithelium from cancer patients than in that from normal individuals in which the nuclear factor (NF)-κB pathway is not activated. We analyzed TFF1 expression in ex vivo samples of gastric mucosa from cancer patients, and in MKN45 gastric cancer cell line after exposure to proinflammatory cytokines interleukin (IL)-1β or tumor necrosis factor (TNF)-α, that activate the NF-κB pathway. We found that IL-1β and TNF-α activate the NF-κB pathway, as reflected in the nuclear expression of p65 and the activation of p-IκBα, and downregulate TFF1 expression after 1 or 2 h of exposure. Moreover, cells in the superficial gastric epithelium in ex vivo samples co-expressed TFF1/p65 at cellular level, whereas tumor cells did not. In summary, downregulation of TFF1 expression during gastric neoplastic transformation is associated with activation of the NF-κB pathway through IL-1β or TNF-α, but other regulatory mechanisms might also be involved.

Comparison of global gene expression of gastric cardia and noncardia cancers from a high-risk population in china

Objective

To profile RNA expression in gastric cancer by anatomic subsites as an initial step in identifying molecular subtypes and providing targets for early detection and therapy.

Methods

We performed transcriptome analysis using the Affymetrix GeneChip U133A in gastric cardia adenocarcinomas (n = 62) and gastric noncardia adenocarcinomas (n = 72) and their matched normal tissues from patients in Shanxi Province, and validated selected dysregulated genes with additional RNA studies. Expression of dysregulated genes was also related to survival of cases.

Results

Principal Component Analysis showed that samples clustered by tumor vs. normal, anatomic location, and histopathologic features. Paired t-tests of tumor/normal tissues identified 511 genes whose expression was dysregulated (P<4.7E-07 and at least two-fold difference in magnitude) in cardia or noncardia gastric cancers, including nearly one-half (n = 239, 47%) dysregulated in both cardia and noncardia, one-fourth dysregulated in cardia only (n = 128, 25%), and about one-fourth in noncardia only (n = 144, 28%). Additional RNA studies confirmed profiling results. Expression was associated with case survival for 20 genes in cardia and 36 genes in noncardia gastric cancers.

Conclusions

The dysregulated genes identified here represent a comprehensive starting point for future efforts to understand etiologic heterogeneity, develop diagnostic biomarkers for early detection, and test molecularly-targeted therapies for gastric cancer.

Loss of trefoil factor 1 is regulated by DNA methylation and is an independent predictive factor for poor survival in advanced gastric cancer

Trefoil factor 1 (TFF1) is considered to be a tumor suppressor gene in gastric cancer. However, the role of TFF1 expression and its regulation in gastric cancer patients remain unclear. The aims of this study were to clarify the clinical significance of TFF1 and to determine its regulatory mechanisms. We assessed the immunohistochemical expression of TFF1 in 182 gastric cancer patients and examined whether or not TFF1 is associated with the clinicopathological factors and patient survival. In vitro study using TFF1 knockdown gastric cancer cells evaluated the role of TFF1 in cancer invasion. Bisulfite sequencing was performed to assess DNA methylation of TFF1 in cells and resected tissues. Patients with low expression of TFF1 showed a significantly deeper invasion of the tumor than those with high expression (p=0.037). Low expression of TFF1 was also associated with a poor survival (p=0.029) in 108 patients who were treated by surgery alone. Both TFF1 expression and lymph node metastasis are independent predictive factors for disease-specific survival in a multivariate analysis. In an in vitro study, invasive power of the cells was significantly increased in the TFF1‑deficient cells compared with the control cells. Bisulfate sequencing showed that TFF1 expression is strongly dependent on DNA methylation in both gastric cancer cells and tissues. Interestingly, methylation status of two specific CpG sites, which are located close to a TATA box and hypoxia response element (HRE), determined the TFF1 expression in the resected tissues. TFF1 expression is silenced by DNA methylation and is associated with tumor invasion and a poor survival in gastric cancer patients. The expression and̸or methylation status of TFF1 may, therefore, serve as a useful biomarker for predicting survival in patients with advanced gastric cancer.

Identification of differentially expressed genes in gastric cancer by high density cDNA microarray

The identification of molecular markers for diagnosis, treatment, and prognosis is a significant issue in the management of patients with gastric cancer. We compared the expression profiles of 23 gastric cancers and 22 normal gastric tissues using cDNA microarrays. We divided the samples into two sets, 11 pairs as a training set and 12 unpaired gastric cancer and 11 unpaired normal gastric tissues as a test set. We selected significant genes in the training set and validated the significance of the genes in the test set. We obtained 238 classifier genes that showed a maximum cross-validation probability and clear hierarchical clustering pattern in the training set, and showed excellent class prediction probability in the independent test set. The classifier genes consisted of known genes related to the biological features of cancer and 28% unknown genes. We obtained genome-wide molecular signatures of gastric cancer, which provides preliminary exploration data for the pathophysiology of gastric cancer.

Programmed cell death 6 (PDCD6) as a prognostic marker for gastric cancers

Programmed cell death 6 (PDCD6) plays an important role in apoptotic cell death and tumorigenesis. In this study, we investigated whether PDCD6 contributes to the development and/or progression of gastric cancers. PDCD6 protein expression was examined in 169 advanced gastric cancer specimens by immunohistochemistry and then correlated with clinicopathologic parameters. We also analyzed mutations, methylation status, and alterations in DNA copy number and mRNA transcripts, and protein expression of PDCD6 in gastric cancers. The effect of PDCD6 on cell viability and death was further examined in wild- and mutant-type PDCD6 transfected AGS and HEK293T cell lines. Increased expression of PDCD6 expression was detected in 124 (73.4%) out of 169 gastric cancer specimens. Statistically, altered expression of PDCD6 was closely associated with survival rates (P = 0.0069). One non-sense mutation was found at codon 175 of PDCD6, and no hypermethylation was found in gastric cancers. Decreased copy numbers and mRNA expression of PDCD6 were found in 7 (16.7%) and 10 (23.8%) of 42 gastric cancer specimens, respectively. AGS and HEK293T cells transfected with wild-type PDCD6 showed marked inhibition of cell viability and induction of cell death via activation of mitochondrial cell death pathways, whereas mutant-type PDCD6 showed partial ablation of tumor suppressor activity. In addition, AGS cells transfected with wild-type PDCD6 and treated with 5-FU showed synergistic inhibition of cell viability (P < 0.001). These data provide evidence that the PDCD6 gene is a significant prognostic biomarker for advanced gastric cancer patients.

Loss of TFF1 is associated with activation of NF-κB-mediated inflammation and gastric neoplasia in mice and humans

Trefoil factor 1 (TFF1) is a tumor suppressor gene that encodes a peptide belonging to the trefoil factor family of protease-resistant peptides. Although TFF1 expression is frequently lost in gastric carcinomas, the tumorigenic pathways this affects have not been determined. Here we show that Tff1-knockout mice exhibit age-dependent carcinogenic histological changes in the pyloric antrum of the gastric mucosa, progressing from gastritis to hyperplasia, low-grade dysplasia, high-grade dysplasia, and ultimately malignant adenocarcinoma. The histology and molecular signatures of gastric lesions in the Tff1-knockout mice were consistent with an inflammatory phenotype. In vivo, ex-vivo, and in vitro studies showed that TFF1 expression suppressed TNF-α-mediated NF-κB activation through the TNF receptor 1 (TNFR1)/IκB kinase (IKK) pathway. Consistent with these mouse data, human gastric tissue samples displayed a progressive decrease in TFF1 expression and an increase in NF-κB activation along the multi-step carcinogenesis cascade. Collectively, these results provide evidence that loss of TFF1 leads to activation of IKK complex-regulated NF-κB transcription factors and is an important event in shaping the NF-κB-mediated inflammatory response during the progression to gastric tumorigenesis.

Inactivation of the Gastrokine 1 gene in gastric adenomas and carcinomas

Gastrokine 1 (GKN1) plays a role in the gastric mucosal defence mechanism and may be a gastric tumour suppressor. We have investigated whether inactivation of the GKN1 gene is involved in the development and/or progression of gastric cancers. GKN1 protein expression was examined in gastric adenomas and cancer and we also analysed GKN1 mutation and epigenetic alteration, DNA copy number change and mRNA transcript expression. The effect of GKN1 on cell proliferation and death was examined in wild-type GKN1-transfected AGS gastric cancer cells. Reduced or loss of GKN1 expression was detected in 36 (90%) and 170 (89.5%) of 40 adenomas and 190 gastric cancers, respectively. Statistically, there was no significant relationship between altered expression of GKN1 protein and clinicopathological parameters, including depth of invasion, location and lymph node metastasis (χ(2) test, p > 0.05). In western blot analysis, absence or reduced expression was found in 21 (84.0%) of 25 gastric carcinomas. No mutation was detected in gastric tumours, and hypermethylation of GKN1 gene was found in two tumours. DNA copy number and mRNA transcript of GKN1 were significantly decreased in gastric cancers. In functional analysis, AGS gastric cancer cells transfected with GKN1 wild-type showed marked inhibition of cell proliferation and induction of cell death. These data suggest that inactivation of the GKN1 gene may play an important role in the development of sporadic gastric cancers, as an early event.

Gene expression changes in patient-matched gastric normal mucosa, adenomas, and carcinomas

A subset of gastric carcinomas shows histologic evidence of a multistep process, progressing from gastric adenoma to gastric carcinoma. We examined gene expression changes during the gastric adenoma-carcinoma sequence in 26 snap-frozen samples (normal mucosa, adenoma, and carcinoma samples from eight patients and two additional carcinomas) by oligonucleotide microarray. Unsupervised hierarchical clustering analysis demonstrated differential gene expression between gastric normal mucosa, adenomas and carcinomas. We identified 319 and 422 genes differentially regulated in adenoma and carcinoma, respectively, relative to normal mucosa, using a combination of Welch's t-test and fold-change analysis. Applying a combination of robust multi-category support vector machines to the data, reveal that 39 and 21 genes were gradually up- and down-regulated, respectively, in succession in normal mucosa, adenoma, and carcinoma samples. We validated gene expression levels of four genes: hydroxyprostaglandin dehydrogenase 15 (HPGD), follistatin-like 1, trefoil factor 1 (TTF1) and trefoil factor 2 (TFF2) by RT-PCR and found direct correlation with microarray results. The expressions of the TFF2 and HPGD genes were further evaluated by immunohistochemistry in 103 adenomas and 70 carcinomas; expression of both proteins was decreased in these tissues. The progressive alteration in gene expression in the transition from normal mucosa to carcinoma suggests that these changes may play critical roles in gastric carcinogenesis.

Foxp3 expression in p53-dependent DNA damage responses

The forkhead transcription factor, Foxp3, is thought to act as a master regulator that controls (suppresses) expression of the breast cancer oncogenes, SKP2 and HER-2/ErbB2. However, the mechanisms that regulate Foxp3 expression and thereby modulate tumor development remain largely unexplored. Here, we demonstrate that Foxp3 up-regulation requires p53 function, showing that Foxp3 expression is directly regulated by p53 upon DNA damage responses in human breast and colon carcinoma cells. Treatment with the genotoxic agents, doxorubicin or etoposide, induced Foxp3 expression in p53-positive carcinoma cells, but not in cells lacking p53 function. Furthermore, knock down of endogenous wild-type p53 using RNA interference abrogated Foxp3 induction by genotoxic agents, and exogenous expression of p53 in cells lacking p53 restored the responsiveness of Foxp3 to DNA-damaging stresses. In addition, Foxp3 knock down blunted the p53-mediated growth inhibitory response to DNA-damaging agents. These results suggest that induction of Foxp3 in the context of tumor suppression is regulated in a p53-dependent manner and implicate Foxp3 as a key determinant of cell fate in p53-dependent DNA damage responses.

Generation of expression clone set for functional proteomics of human gastric and liver cancers

Two thousand sixty-eight multi-purpose expression clones for the 326 candidate genes related to gastric or liver cancers were constructed using the Gateway system. These clones can be expressed as His, Glutathione-S-transferase (GST) or Enhanced version of the green fluorescent protein (EGFP) fusion proteins in E. coli, insect cells or mammalian cells. For the 246 E. coli expression clones, the GST fusion proteins had greater expression efficiency and solubility than the His fusion proteins. Approximately 20% of the expressed proteins had unexpected molecular weights. A detailed sequence analysis of these clones revealed frameshift mutations resulting from insertion, deletion or substitution of nucleotides. The results indicate that these changes in the candidate genes may affect the occurrence of gastric or liver cancers. In addition, when 105 proteins, which were expressed in E. coli at very low or undetectable levels, were expressed in insect cells, 76% of the proteins were expressed very well and most were soluble. We also found that most of the 30 proteins prepared using EGFP mammalian expression clones were localized to cellular compartments expected by Gene ontology (GO) and this localization was unaffected if the EGFP-fusion was at the N-terminal or C-terminal region of the protein. Antibody production and subcellular localization analysis of the candidate genes as well as a screen of genes involved in carcinogenesis pathways are currently in progress using these expression clones. These studies provide a valuable resource for developing a better understanding of the molecular mechanism of carcinogenesis in both gastric and liver cancer and would be very helpful in diagnosis and therapeutic predictions.

Molecular aspects in the diagnosis of gastric cancer

BACKGROUND

Gastric cancer (GC) represents the second most common cause of cancer-related death worldwide. The prognosis remains poor, with limited treatment options. A better understanding of the initiation and progression of GC would enable the development of general screening strategies and individualized treatment modalities.

OBJECTIVE

The assessment of tools and molecular markers for the early detection and diagnosis of GC.

METHODS

Human clinical studies published within the past 5 years are reviewed. Also, significant previous data on markers in clinical use or on relevant animal or cell culture experiments are considered.

RESULTS/CONCLUSION

Serum-based screening strategies are not ready for routine application but represent an opportunity for the identification of individuals at high risk with the need for primary gastroscopy and further surveillance, which would ultimately improve survival and prognosis of GC. Infection with Helicobacter pylori represents the principal risk factor for gastric carcinogenesis. Bacterial virulence and host genetic factors contribute to individual susceptibility. Key molecular alterations in gastric carcinogenesis are related to intra- and extracellular cascades that regulate cell proliferation, tumor invasion and metastastic spread. For the development of effective prevention and treatment modalities, it is essential to unravel the basic mechanisms of gastric carcinogenesis.

p34SEI-1 inhibits apoptosis through the stabilization of the X-linked inhibitor of apoptosis protein: p34SEI-1 as a novel target for anti-breast cancer strategies

The p34(SEI-1) protein exerts oncogenic effects via regulation of the cell cycle, which occurs through a direct interaction with cyclin-dependent kinase 4. Such regulation can increase the survival of various types of tumor cells. Here, we show that the antiapoptotic function of p34(SEI-1) increases tumor cell survival by protecting the X-linked inhibitor of apoptosis protein (XIAP) from degradation. Our findings show that p34(SEI-1) inhibits apoptosis. This antiapoptotic effect was eliminated by the suppression of p34(SEI-1) expression. We also determined that direct binding of p34(SEI-1) to the BIR2 domain prevents ubiquitination of XIAP. Interestingly, p34(SEI-1) expression is absent or weak in normal tissues but is strongly expressed in tissues obtained from patients with breast cancer. Furthermore, the expression levels of p34(SEI-1) and XIAP seem to be coordinated in human breast cancer cell lines and tumor tissues. Thus, our findings reveal that p34(SEI-1) uses a novel apoptosis-inhibiting mechanism to stabilize XIAP.

Inverse association between Raf Kinase Inhibitory Protein and signal transducers and activators of transcription 3 expression in gastric adenocarcinoma patients: implications for clinical outcome

PURPOSE

Raf Kinase Inhibitory Protein (RKIP) plays a pivotal role in cancer by regulating apoptosis induced by chemotherapeutic agents, or immune-mediated stimuli and is a metastasis suppressor protein. The signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is frequently activated in gastric adenocarcinomas, thereby promoting tumor growth. We examined the expression patterns of RKIP and STAT3 with regard to human gastric cancer, predicting that elevated RKIP status may favor clinical outcome.

EXPERIMENTAL DESIGN

Tissue microarrays were created from samples from 143 patients with gastric adenocarcinomas. The microarrays were immunohistochemically stained for RKIP and STAT3, and the intensity and extent of the staining was semiquantitatively scored.

RESULTS

In intestinal-type gastric adenocarcinomas, RKIP and STAT3, expression were inversely associated. Cytoplasmic RKIP expression directly correlated with patient survival. Nuclear STAT3 expression inversely correlated with survival. In the diffuse tumor type, no significant correlation was found between RKIP and patient outcome. In the intestinal-type gastric adenocarcinoma, multivariate analysis adjusted for treatment types revealed RKIP and tumor stage to be significant independent predictors of survival. In the diffuse tumor type, stage was the only significant predictor of survival.

CONCLUSION

These results indicate the predictive and protective role of cytoplasmic RKIP expression in gastric adenocarcinoma of the intestinal subtype. In contrast, nuclear STAT3 expression is associated with poor patient prognosis in the intestinal subtype. Significantly, we show an inverse association between RKIP and STAT3 and a positive correlation between RKIP and patient survival.

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.