Gastric cancer (GC) is one of the most common malignancies around the world, and the incidence of GC is increasing in the past decades. In addition to genetic modifications, epigenetic alterations catalyzed by DNA methyltransferases (DNMTs) are a well-characterized epigenetic hallmark in gastric cancer. Nowadays, DNA methylation landscape is essential for maintaining the silence of tumor suppressor genes (TSGs). As an important group of peptide, TFF family has been confirmed to function as a TSG in various kinds of cancers. However, whether TFFs could be modified by DNA methylation in gastric cancer remains unknown. In this study, we initially screened out two expression profiles about GC from Gene Expression Omnibus (GEO) database. The higher expressions of TFF1 and TFF2 were observed in GC tumor tissues than normal tissues. Additionally, we illustrated that the expressions of TFF1/TFF2 were associated to the overall survival (OS) and tumor free survival (TFS) of GC patients via through the Kaplan-Meier analysis. Subsequently, the integrative analysis was performed to estimate the DNA methylation level of each site in TFF1/TFF2 CpG islands. Importantly, our findings indicated that hyper-methylation of cg01886855 and cg26403416 were separately responsible for the downregulation of TFF1 and TFF2 in GC samples. Besides, utilizing the gain of function assay, we demonstrated that TFF1/TFF2 could suppress the proliferation of GC cells. Based on these results, We identified that TFF1 and TFF2 acted as the putative tumor suppressors in gastric cancer, which suggested that TFFs could be two candidate biomarkers for predicting tumor recurrence in gastric cancer patients. Furthermore, these findings highlight a potential therapeutic approach in targeting the TFFs for the treatment of gastric cancer.

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

Keywords: retinoblastoma, RB, gastric inhibitory polypeptide receptor, GIPR, trefoil factor family peptide, TFF1, CAM, tumorigenesis, MK0893, miR5-542-5p