Piwil2 modulates the invasion and metastasis of prostate cancer by regulating the expression of matrix metalloproteinase-9 and epithelial-mesenchymal transitions.

Piwi-like RNA-mediated gene silencing 2 (Piwil2) is an oncogene that is highly expressed in breast, gastric, colorectal and papillary thyroid cancer. As a candidate oncogene, its role in prostrate cancer has yet to be elucidated. In the present study, 30 tumor specimens and four prostate cancer cell lines were analyzed. The total RNA and protein from the specimens and the cells were analyzed using quantitative polymerase chain reaction and western blotting, respectively. The expression of Piwil2 in PC-3 cells was knocked down using specific small hairpin RNA. Transwell assays and wound-healing models were used to assess cell invasion and migration. In addition, the expression of several factors associated with epithelial-mesenchymal transitions (EMT) were evaluated by western blotting. The results revealed that the Piwil2 gene was associated with the Gleason score and the tumor-node-metastasis stage of the tumor tissues. Cell invasion and migration decreased significantly in PC-3 cells with knocked-down Piwil2. In addition, silencing Piwil2 downregulated the expression of N-cadherin, Twist and vimentin and upregulated the expression of E-cadherin, factors associated with EMT, and also reduced the expression of matrix metalloproteinase-9. Piwil2 was demonstrated to possess an important role in the invasive ability of prostate cancer, and therefore, may be a potential therapeutic target for the treatment of this cancer.