Effect and mechanism of downregulating the long-chain noncoding RNA TM4SF1-AS1 on the proliferation, apoptosis and invasion of gastric cancer cells

BACKGROUND: To investigate long-chain noncoding TM4SF1-AS1 in gastric cancer (GC) tissues and cells. METHODS: TM4SF1-AS1 in 40 GC tissues and adjacent tissues was detected and compared using real-time fluorescence quantitative PCR (qRT-PCR). TM4SF1-AS1 in MKN28 and SGC7901 GC cells was downregulated using small interfering RNA (shRNA). The cells were grouped into an interference group (shTM4SF1-AS1 group) and a control group (shControl group). MTT and Transwell tests were applied to determine the proliferation and invasion of the cells in both groups, and flow cytometry was performed to assess the apoptosis rate in the two groups. Western blotting was performed to determine changes in key proteins in cells during the epithelial-to-mesenchymal transition (EMT) and in the TM4SF1 and PI3K-AKT signalling pathways in response to the downregulation of TM4SF1-AS1. RESULTS: The proliferation of MKN28 and SGC7901 in the shTM4SF1-AS1 group was significantly inhibited at 48 h and 72 h compared to that in the shControl group (all P < 0.05). In the shTM4SF1-AS1 group, the number of invaded MKN28 and SGC7901 cells was significantly lower than that in the shControl group (all P < 0.05). Apoptosis in the MKN28 and SGC7901 shTM4SF1-AS1 groups was significantly higher than that in the shControl group (all P < 0.05). Compared to those in the shControl group, levels of E-cadherin in EMT-related proteins were significantly elevated (P < 0.01), while levels of N-cadherin, Snail and Twist1 were significantly decreased (all P < 0.01). After silencing the expression of LncTM4SF1-AS1, the expression levels of TM4SF1 in the shTM4SF1-AS1 group were downregulated compared to those in the shControl group, and the p-PI3K and p-AKT proteins in the PI3K-AKT signalling pathway in the shTM4SF1-AS1 group were downregulated compared to those of the shControl group. CONCLUSIONS: TM4SF1-AS1 is upregulated in gastric cancer tissues and cells. Interfering with and downregulating its expression inhibit cancer cell proliferation, invasion and the EMT and promote apoptosis. The underlying mechanism for these effects is related to silencing the TM4SF1 and PI3K-AKT signalling pathways. TM4SF1-AS1 may be a potential therapeutic target for gastric cancer.