Oncogenic role of LYN in human gastric cancer via the Wnt/β-catenin and AKT/mTOR pathways.

LYN kinase (LYN) is a member of the Src tyrosine kinase family, which plays an important role in multiple tumor-related functions. The current study demonstrated that LYN functions as a pro-oncogene in AGS gastric cancer cells. It was found that LYN expression levels were significantly raised in gastric cancer tissue and were significantly associated with the pathological grades of patients with gastric cancer. This was accomplished by knocking down LYN in AGS cells using short hairpin RNA (shRNA) plasmid transfection, with reverse transcription-quantitative PCR detection verifying the effectiveness of RNA interference. It was found that the cell proliferation and colony formation abilities of AGS cells were significantly inhibited, using CCK-8 and clone formation assays, respectively. Furthermore, LYN knockdown was found to induce apoptosis and inhibit both migration and invasion in AGS cells, using flow cytometry and Transwell assays, respectively. A mechanical investigation further suggested that LYN knockdown resulted in the activation of the mitochondrial apoptotic pathway. Likewise, the Wnt/β-catenin pathway was inactivated by LYN knockdown, including decreased levels of Wnt3a, β-catenin, snail family transcriptional repressor (Snail)1 and Snail2. Epithelial-mesenchymal transition mesenchymal markers (including N-cadherin and vimentin) were also found to be downregulated, and E-cadherin was upregulated in LYN-silenced AGS cells. Finally, the AKT/mTOR pathway was found to be downregulated by LYN knockdown in AGS cells, including decreased levels of phosphorylated (p)-AKT (Ser473), p-mTOR (Ser2448), and the down-stream effector p70S6 kinase (p70S6K). Furthermore, the AKT pathway activator, insulin like growth factor-1 (IGF-1), was found to reverse the inhibitory effects of LYN knockdown on the proliferation, migration and invasion of AGS cells. In conclusion, the current study demonstrated that LYN plays an oncogenic role in the proliferation, survival and movement of human gastric cancer cells by activating the mitochondrial apoptotic pathway, and downregulating the Wnt/β-catenin and AKT/mTOR pathways. The current research provides a comprehensive insight into the regulation of LYN in gastric cancer and may help with the development of new tumor treatment strategies.