Downregulation of microRNA‑574 in cancer stem cells causes recurrence of prostate cancer via targeting REL.

miR‑574‑5p has been reported involved in the pathogenesis of numerous human malignancies such as colorectal and lung cancer. In this study, we aimed to explore the roles of REL and miR‑574 in the recurrence of prostate cancer (PCa) and to identify the underlying molecular mechanisms. Our literature search found that miR‑574 is regulated in cancer stem cells (CSCs), and next we used the microRNA (miRNA) database (www.mirdb.org) to find REL as a target of miR‑574. Luciferase assay was performed to verify the miRNA/target relationship. Oligo-transfection, real‑time PCR and western blot analysis were used to support the conclusions. We validated REL to be the direct gene via luciferase reporter assay system, and real‑time PCR and western blot analysis were also conducted to study the mRNA and protein expression level of REL between different groups (recurrence and non‑recurrence) or cells treated with scramble control, miR‑574 mimics, REL siRNA and miR‑574 inhibitors, indicating the negative regulatory relationship between miR‑574 and REL. We also investigated the relative viability of prostate CSCs when transfected with scramble control, miR‑574 mimics, REL siRNA and miR‑574 inhibitors to validate miR‑574 to be positively interfering with the viability of prostate CSCs. We then investigated the relative apoptosis of prostate CSCs when transfected with scramble control, miR‑574 mimics, REL siRNA and miR‑574 inhibitors. The results showed miR‑574 inhibited apoptosis. In conclusion, miR‑574 might be a novel prognostic and therapeutic target in the management of PCa recurrence.