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Telomeric repeat binding factor 1 (TERF1) has been identified as a tumor suppressor gene in numerous types of human cancer. However, the expression of TERF1 and its mechanism in prostate cancer (PCa) remains unclear. The present study aimed to explore the expression and functions of TERF1 in PCa. The UALCAN database was used to analyze the differential expression of TERF1 between normal prostate tissue and primary PCa tissue. Cell apoptosis was analyzed by Annexin V/propidium iodide staining, and wound healing and Transwell assays were used to detect the cell migration and invasion abilities, respectively. The cell viability was analyzed using an MTT assay. Reverse transcription‑quantitative PCR and western blotting were used to analyze the mRNA and protein expression levels, respectively, of epithelial‑mesenchymal transition (EMT) markers following TERF1 knockdown in the PC3 cell line. A dual luciferase reporter assay was used to verify the association between TERF1 and microRNA (miR)‑155 predicted by bioinformatics analysis. Rescue experiments were performed to determine the role of the miR‑155/TERF1 axis in regulating the cellular behaviors of PCa. The results demonstrated that the expression levels of TERF1 in the primary prostate tumors were significantly downregulated compared with in prostate normal tissue. TERF1 silencing was discovered to significantly promote cell viability, migration and invasion, while suppressing cell apoptosis. The impact of TERF1 on PC3 cells was suggested to occur through the EMT pathway. TERF1 was confirmed to be the direct target of miR‑155. The overexpression of miR‑155 promoted the viability, migration and invasion, while suppressing the apoptosis of the PC3 cell line, while the knockdown of miR‑155 in PC3 cells achieved the opposite trends. In addition, TERF1 overexpression reversed the promotive effects of upregulated miR‑155 expression levels on the migration and apoptosis of PC3 cells. On the contrary, the knockdown of TERF1 reversed the migration and apoptosis abilities of the downregulated miR‑155 expression levels on the cellular behaviors of PC3 cells. In conclusion, TERF1, as a direct target of miR‑155, was discovered to be significantly downregulated in PCa, which was suggested to promote the migration and invasion of PCa via the EMT pathway. [ABSTRACT FROM AUTHOR]