Epithelial-mesenchymal transition of circulating tumor cells in prostate cancer is promoted by survivin

OBJECTIVE: Recent studies demonstrated that circulating tumor cells (CTCs) contribute to the metastasis of prostate cancer. Survivin knockout could inhibit epithelial-mesenchymal transition (EMT) and suppress several metastatic tumors. In this study, we examined the potential involvement of survivin in EMT in CTCs. METHODS: CTCs were isolated from the peripheral blood of 100 patients with prostate cancer as EpCAM(+)/CD45(−) cells via FACS sorting and identified by immunofluorescence staining of prostate-specific antigen (PSA). CTCs and DU145 cells were transfected with survivin siRNA. Then, the levels of survivin, E-cadherin, and vimentin in CTCs and DU145 cells were detected via immunofluorescence staining, and the invasiveness of CTCs and DU145 cells was examined using a Transwell chamber. RESULTS: The results revealed the abundant expression of PSA in the cytoplasm of CTCs. Transfection of survivin siRNA significantly decreased the levels of survivin and vimentin in CTCs and DU145, whereas that of E-cadherin was significantly increased, suggesting survivin plays an important role in EMT of CTCs. In addition, survivin siRNA significantly inhibited the invasiveness of CTCs and DU145 cells. CONCLUSIONS: Survivin plays an important role in EMT of CTCs in prostate cancer, which might mediate the metastasis and invasion of prostate cancer.