tRF-27-87R8WP9N1E5 serves as a prognostic biomarker and tumor suppressor in gastric cancer by targeting the WNT4 pathway via Ago2.

Gastric cancer (GC) poses a significant global health burden, creating critical demands for early diagnostic biomarkers and novel therapeutic targets. tRNA-derived fragments (tRFs) have recently emerged as key regulatory molecules in tumorigenesis. However, the roles of tRFs in GC are largely unknown. The diagnostic and prognostic significance of tissue tRF-27-87R8WP9N1E5 (tRF-27) was evaluated by receiver operating characteristic (ROC) curve, survival, and Cox regression analyses. Gain- and loss-of-function studies in vitro and in vivo were performed to investigate its biological effects and regulatory mechanisms. RNA immunoprecipitation, dual-luciferase reporter, and immunohistochemical assays were used to validate WNT family member 4 (WNT4) mRNA as a direct target of tRF-27. Tissue tRF-27 expression progressively decreased from healthy controls to early and advanced GC. tRF-27 showed diagnostic value for GC, with the highest performance in advanced GC (the area under ROC curve = 0.780), and retained discriminatory capacity in patients negative for conventional serum biomarkers. Low tRF-27 expression was associated with poorer overall survival, while multivariate analysis identified tRF-27 as an independent protective prognostic factor (Hazard Ratio = 0.478, P = 0.020). Functionally, tRF-27 suppressed GC cell proliferation, colony formation, migration, and cell cycle, while promoting apoptosis. Mechanistically, tRF-27 directly bound the 3' untranslated region (3'UTR) of WNT4 mRNA in an Argonaute 2 (Ago2) dependent manner, inhibiting WNT4/β-catenin signaling and thereby mediating tumor-suppressive effects. In vivo, tRF-27 overexpression significantly inhibited xenograft tumor growth. tRF-27 functions as a tumor-suppressive regulator of the WNT4/β-catenin pathway and represents a promising complementary biomarker with diagnostic and prognostic relevance in GC. The tumor suppressor role and potential applications of tRF-27 in gastric cancer. tRF-27 may become a potential biomarker of gastric cancer and a promising candidate target for intervention. tRF-27 is downregulated in gastric cancer, while its restoration suppresses malignant phenotypes. Mechanistically, tRF-27 binds to the 3' untranslated region (UTR) of WNT4 mRNA and associates with Argonaute 2 (Ago2) to form an RNA-induced silencing complex (RISC), resulting in suppression of WNT4 expression and its downstream effectors, including β-catenin, TCF7, and Cyclin D1, thereby inhibiting gastric cancer cell proliferation and migration.