Male-specific long non-coding RNA testis-specific transcript, Y-linked 15 promotes gastric cancer cell growth by regulating Wnt family member 1/β-catenin signaling by sponging microRNA let-7a-5p

The present study is aimed to investigate the regulatory effects and related mechanism of long non-coding RNA testis-specific transcript, Y-linked 15 (TTTY15) in gastric carcinoma (GC) cell proliferation, migration, invasion, apoptosis and epithelial–mesenchymal transition (EMT). TTTY15 expression in GC tissue samples and cells was detected by quantitative real-time PCR (qRT-PCR), and the correlation between TTTY15 expression and GC clinicopathological indicators was analyzed. Cell counting kit-8 (CCK-8), BrdU, flow cytometry and Transwell assays were performed for detecting GC cell proliferation, migration, invasion and apoptosis. Western blot was performed for detecting the expressions of EMT-associated proteins (N-cadherin and E-cadherin), Wnt family member 1 (Wnt1) protein and β-catenin protein. Bioinformatics analysis was conducted to predict, and RNA immunoprecipitation (RIP) assay and dual-luciferase reporter gene assay were performed to verify the targeted relationships of microRNA let-7a-5p (let-7a-5p) with TTTY15 and Wnt1 mRNA 3'UTR. It was found that TTTY15 expression was significantly up-regulated in GC tissues and cells, and was associated with advanced TNM stage and poor tumor differentiation. TTTY15 overexpression promoted GC cell proliferation, migration and invasion, the expressions of N-cadherin, Wnt1 and β-catenin protein, and inhibited the apoptosis and E-cadherin expression, while knocking down TTTY15 had the opposite effects. TTTY15 directly targeted let-7a-5p and negatively regulated its expression. Wnt1 was the target gene of let-7a-5p, and TTTY15 could indirectly and positively regulate Wnt1 expression. In conclusion, TTTY15 promotes GC progression, by regulating the let-7a-5p/Wnt1 axis to activate the Wnt/β-catenin pathway.