OBJECTIVETo investigate the effects of the over-expression of hypoxia-inducible factor-1alpha (HIF-1alpha) on the epithelial-mesenchymal transition (EMT) and invasive potency of LNCaP cells in vitro and in vivo.

METHODSWe cultured LNCaP cells stably expressing HIF-1alpha (LNCaP/HIF-1alpha) and LNCaP cells, identified the over-expression of HIF-1alpha, determined the proliferation of the two cell lines by MTT assay and the level of PSA in the supernatant of culture medium, and detected the anchorage independent growth by soft-agar colony formation assay. A subcutaneous tumor model was established in nude mice by injecting LNCaP/HIF-1alpha and LNCaP cells followed by observation of the tumor growth. Tumor specimens were obtained for immunohistochemistry.

RESULTSThe over-expression of HIF-1alpha was confirmed in the LNCaP/HIF-1alpha cells by immunofluorescence staining and Western blotting. The level of PSA was obviously decreased in LNCaP/HIF-1alpha as compared with that in LNCaP cells. MTT assay identified the increased proliferation of LNCaP/HIF-1alpha cells. The cell colony forming ability of the LNCaP cells was significantly lower than that of the LNCaP/HIF-1alpha cells. The rate of tumorigenesis was increased and its time shortened in the LNCaP/HIF-1alpha group. Immunohistochemistry revealed an up-regulated expression of vimentin and a down-regulated expression of E-cadherin in the tumor specimens.

CONCLUSIONThe overexpression of HIF-1alpha can up-regulate the expression of vimentin and down-regulate the expression of E-cadherin, which may enhance the invasive potency of LNCaP cells by inducing EMT.