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OBJECTIVE: This study was aimed to investigate the expression characteristics of ETS variant 4 (ETV4) in gastric cancer (GCa), and to further explore whether it promotes the development of GCa by regulating KDM5D. PATIENTS AND METHODS: Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) was performed to examine the expression of ETV4 in 35 pairs of tumor tissue and paracancerous tissue specimens collected from GCa patients, and the interplay between ETV4 expression and clinical indexes, as well as the prognosis of GCa patients, were analyzed. Meanwhile, the expression of ETV4 in GCa cell lines was verified using qRTPCR assay. Furthermore, ETV4 knockdown model was constructed using lentivirus in GCa cell lines including AGS and BGC-823, and then, the transwell invasion and cell wound healing assays were applied to analyze the effect of ETV4 on the biological function of GCa cells. In addition, an in-depth study of the relationship between ETV4 and KDM5D was conducted. RESULTS: The results of qRT-PCR showed that the expression level of ETV4 in GCa tissue samples was remarkably higher than that in adjacent tissues, and the difference was statistically significant. Compared with patients with low expression of ETV4, the patients with high ETV4 expression had a higher occurrence rate of lymph node or distant metastasis and a lower overall survival rate. Similarly, the metastasis ability of GCa cells in the ETV4 expression knockdown group (sh-ETV4) was remarkably decreased when compared with the sh-NC group. In addition, qRT-PCR results indicated that the protein expression of KDM5D was significantly increased after the knockdown of ETV4. Therefore, it was demonstrated that ETV4 might be able to regulate the malignant progression of GCa via modulating KDM5D expression. Finally, the results of the cell reverse experiment confirmed that the silence of ETV4 could reverse the malignant progression of GCa induced by the downregulation of KDM5D. CONCLUSIONS: ETV4 expression was found remarkably elevated in GCa tissues and was significantly associated with the occurrence of lymph node or distant metastasis and poor prognosis. In addition, ETV4 might promote GCa cell metastasis by modulating KDM5D. [ABSTRACT FROM AUTHOR]