A 5`-tRNA Derived Fragment NamedtiRNA-Val-CAC-001 Works as a Suppressor in Gastric Cancer

BACKGROUND: Gastric cancer (GC) is a common type of gastrointestinal tumor in the world. Transfer RNA (tRNA) derived fragments (tsRNAs) implicate various cancers, but their roles in GC remain unclear. Our study aimed to investigate the potential biological functions and molecular mechanisms of tsRNAs in GC. METHODS: Differentially expressed tsRNAs were identified using high-throughput sequencing. The expression levels of tsRNAs were validated in 62 paired GC tissues and adjacent normal tissues using RT-qPCR. In vitro functional assays were used to evaluate the influences of tsRNAs on GC cells. The potential mechanisms underlying tsRNAs were explored using bioinformatics analysis,RT-qPCR, RNA immunoprecipitation assays and Western blot. RESULTS: We found that tiRNA-Val-CAC-001 was downregulated in GC tissues and cells, and demonstrated that tiRNA-Val-CAC-001 was a tsRNA sheared from mature tRNA-Val and mainly localized in the cytoplasm. tiRNA-Val-CAC-001 overexpression inhibited metastasis and proliferation but promoted apoptosis of GC cells; nevertheless, tiRNA-Val-CAC-001 knockdown increased metastasis and proliferation and reduced apoptosis (P<0.05). GO and KEGG analyses indicated tiRNA-Val-CAC-001 may exert its effects via Wnt/β-catenin signaling pathway by targeting LRP6. Following experiments showed that tiRNA-Val-CAC-001 could downregulated the protein levels of LRP6 and β-catenin, but up-regulated p-β-catenin, which confirmed the findings in bioinformatics analysis. CONCLUSION: In conclusion, tiRNA-Val-CAC-001 works as a cancer suppressor in GC by targeting LRP6 via Wnt/β-catenin signaling pathway. tiRNA-Val-CAC-001 may serve as a therapy target and a biomarker of GC in the future. KEY POINTS: tiRNA-Val-CAC-001 is downregulated in gastric cancer tissues and cell lines, tiRNA-Val-CAC-001 has potential to become a novel diagnostic biomarker in gastric cancer, and tiRNA-Val-CAC-001 regulates gastric cancer cells by targeting LRP6.