Int J Oncol. 2013 Mar;42(3):894-902. doi: 10.3892/ijo.2013.1759.

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

Tanaka T, Nakamura J, Kitajima Y, Kai K, Miyake S, Hiraki M, Ide T, Koga Y, Noshiro H.

Department of Surgery, Saga University Faculty of Medicine, Saga 849-8501, Japan.

 

Abstract

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.

PMID: 23291975

 

­Supplement

TFF1 was initially described as an estrogen-inducible gene in a hormone-sensitive breast cancer cell line, MCF-7 (1), but was later found to be spontaneously expressed at a high level in gastric epithelial cells (2). TFF1 stabilize the surface mucus gel layers of the gastric epithelium with mucin core proteins, and plays an important role in the protection and regeneration of the gastric mucosa (3-5). On the other hand, TFF1 is considered to act as a tumor suppressor gene during gastric carcinogenesis (6). Various mechanisms regulating TFF1 expression such as LOH, mutations, epigenetic modification, several transcription factors and hypoxic environment have been reported. (7-13). However, few studies have so far assessed the clinical significance of TFF1 expression and its regulatory mechanism in gastric cancer patients. The present work, for the first time, clearly demonstrated the prognostic value and methylation-mediated regulation of TFF1 in gastric cancer.

TFF1 is rapidly and coordinately secreted from mucus-secreting cells when gastric mucosa suffers from mechanical or chemical damage, and responds to mucosal injury in two main ways.  First, TFF1-response elements located in its own promoter region allow the increasing of TFF expression via auto-induction manner in addition to mucin expression. Second, cell migration occurring as a result of integrated disruption of cell-cell and cell-substratum adhesion prevents apoptosis induced by cell detachment. Several studies also have demonstrated that TFF peptides protect the gastrointestinal mucosa against mechanical injuries in vivo (14, 15). Moreover, recombinant human TFF peptides have been reported to stimulate the migration of epithelial cells to promote the repair of mucosal wounds (3-5). These effects of TFF1 are achieved by activation of several intracellular signaling pathways that converge on ERKs. Phosphorylated ERKs lying the downstream of ErbB is a central regulator of the TFF1-mediated signaling pathway. While, regarding the tumor behavior, it has been reported that TFF1 is involved in both progression and suppression of human solid tumors. Although no definite receptors have been identified, TFF1 is considered to act towards tumor progression by binding to specific receptors. On the contrary, a previous in vitro study showed that TFF1 inhibits the growth of the human gastric adenocarcinoma cell line AGS (16). This indicates the role of TFF1 as a tumor-suppressor in gastric cancer. Oral intake or local administration of TFF1 peptide therefore might inhibit tumor progression of gastric cancer because TFF1 is a small molecule secretary protein.

In conclusion, the expression level and/or methylation status of TFF1 in gastric cancer tissues could therefore be a useful marker predicting the patient survival. Moreover, a novel treatment by TFF1 peptide might be selectively performed in gastric cancer patients with low TFF1 expression, and improve the survival by inhibiting tumor invasion.

Figure1Figure 1. The schema of regulation, function and the signaling pathway of TFF1.

Abbreviations: ERKs (Extracellular Signal-Regulated Kinases), ErbB (v-ErbB Avian Erythroblastic Leukemia Viral Oncogene Homolog), FAK1 (Focal Adhesion Kinase-1), GRB2 (Growth Factor Receptor-Bound Protein-2), SOS1 (Son of Sevenless-1), SHC1 ((SHC (Src Homology-2 Domain Containing) Transforming Protein))), HRas (v-Ha-Ras Harvey Rat Sarcoma Viral Oncogene Homolog), ROCK (Rho-Associated Coiled-Coil-Containing Protein Kinase), MYL (Myosin Light Chain). Thunder mark: mechanical or chemical damage for mucosa.

 

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