Objective:  To investigate the expression of long non-coding RNA(lncRNA) SPATA3-AS1 in gastric cancer tissues and plasma and its clinical significance, and to further explore its effect on gastric cancer cells and its potential mechanism. Methods: Real-time quantitative fluorescence PCR(qRT-PCR) was used to detect the expression level of SPATA3-AS1 in plasma of 80 pairs of gastric cancer and adjacent tissues, 29 gastric cancer patients and 29 healthy subjects. The difference of SPATA3-AS1 expression and clinicopathological characteristics of gastric cancer patients were statistically analyzed. Cell proliferation, clone formation, transwell assay and flow cytometry were used to analyze the effects of SPATA3-AS1 knockdown on gastric cancer cells(AGC and HGC-27).The effect of SPATA3-AS1 knockdown on the expression level of tumor-related molecules was detected by qRT-PCR. Results: SPATA3-AS1 was highly expressed in gastric cancer tissues, and its expression level was correlated with lymph node metastasis, TNM stage, depth of tumor invasion and prognosis. Plasma SPATA3-AS1 was also highly expressed in patients with gastric cancer, and its expression was positively correlated with lymph node metastasis, tumor diameter, and TNM stage of gastric cancer. The area under the receiver operating characteristic curve (ROC curve) for the diagnosis of gastric cancer by the expression level of SPATA3-AS1 in plasma was 0.788. After SPATA3-AS1 knockdown, the proliferation and mobility of AGS and HGC-27 cells were decreased, and apoptosis was enhanced. Meanwhile, the mRNA expression of N-cadherin, Twist1 and Snail were down-regulated while the mRNA expression of E-cadherin was up-regulated in SPATA3-AS1 knockdown cells. Conclusion: SPATA3-AS1 is highly expressed in cancer tissues and plasma of patients with gastric cancer and is associated with prognosis. After SPATA3-AS1 knockdown, the proliferation, migration and invasion of gastric cancer cells were inhibited, and the cell apoptosis was enhanced, which may be related to the regulation of the process of epithelial-mesenchymal transformation.

［Key words］gastric cancer; long noncoding RNA; SPATA3-AS1; epithelial-mesenchymal transition