The targeting of MTDH by miR‑145‑5p or miR‑145‑3p is associated with prognosis and regulates the growth and metastasis of prostate cancer cells.

Studies have rarely been conducted on the role of miRNAs in prostate cancer (PCa) cell progression by directly targeting MTDH, at least to the best of our knowledge. Thus, the present study aimed to identify miRNAs closely related with metadherin (MTDH) and to determine their roles in PCa. For this purpose, the expression levels of MTDH in PCa tissues and cell lines were examined by RT‑qPCR, immunohistochemistry and western blot analysis. By cell transfection, MTDH was either overexpressed in the normal prostate epithelial cell lines or silenced in tumor cell lines to determine cell viability, invasion and migration. Bioinformatics analysis, RT‑qPCR, western blot analysis, dual‑luciferase reporter assay and MTT assay were performed to identify direct the target of MTDH and to examine tumor cell viability. Rescue experiments using the PC‑3 and LNCaP cells were carried out by MTT assay, scratch wound assay, Transwell assay, RT‑qPCR and western blot analysis. Experiments were also conducted using 46 PCa human cancer and adjacent tissues, as wells as on 501 cases of PCa from the TCGA database. It was confirmed that the overexpression of MTDH was associated with a poor prognosis of patients. The overexpression of MTDH was found to promote the viability, invasion and migration of PCa cells. miR‑145‑5p and miR‑145‑3p identified from 16 miRNAs were found to be closely related to PCa and to be the targets of MTDH. Both these miRNAs were found to significantly suppress the growth and metastasis of PCa cells by negatively regulating the expression of MTDH. On the whole, the findings of this study demonstrate that MTDH functions as an oncogene in PCa and the inhibition of MTDH by miR‑145‑5p or miR‑145‑3p suppressed the growth and metastasis of PCa cells. The miR‑145‑5p/MTDH and miR‑145‑3p/MTDH pathways may thus become novel treatment targets for PCa.