(A) Three websites (PITA, microT and PicTar) predicted 35 mRNAs had binding sites with miR-509-3p. (B) PBX3 expression in PCa tissues and adjacent normal tissues were evaluated by qRT-PCR. (C) The binding sites between miR-509-3p and PBX3 obtained from starBase database. (D) The luciferase reporter was implemented to determine the binding correlation between miR-509-3p and PBX3 in LNCaP and DU145 cells. (E) RIP assay was applied to assess the enrichment of HOXA-AS2, miR-509-3p and PBX3 in RISC. (F,G) The qRT-PCR and Western blot analyses were conducted to detect PBX3 expression of both cell lines with two interventions. All data were expressed as the mean ± SD. *P<0.05, **P<0.01, ***P<0.001.