Molecular characterization of epithelial to mesenchymal transition in human prostatic epithelial cells

Epithelial to mesenchymal transition (EMT) has been believed to play a critical role in cancer metastasis. TGFβ has been described as an inducer of EMT in normal mammary epithelial cells by signaling through receptor serine/threonine kinase pathways to regulate epithelial cell plasticity and invasion. In this study, we investigated the EMT cellular responses, including morphologic changes, phenotype switches, invasiveness enhancement, and cellular contraction alteration, in TGFβ stimulated human prostate normal epithelial cells (PZ-HPV-7). Migration of TGFβ treated PZ-HPV-7 cells across matrigel was measured in invasion chambers (8 μm pore size). The cells were treated with or without TGFβ (2 ng/ml) in PrEGM media for 3 days. Immunoblot assay was conducted and it was demonstrated that the induction of vimentin when stimulated by TGFβ was accompanied by a downregulation of E-cadherin, though p-cadherin level was not altered. It was also observed that there was a decrease in cytokaretin 5/6 expression associated with the downregulation of E-cadherin during the induction of EMT. In order to study the cell contraction, three-dimensional collage lattice assay was performed. It was demonstrated that TGFβ-stimulated PZ-HPV-7 cells gained contractility. Our results showed that TGFβ stimulation induced PZ-HPV-7 cells to undergo epithelial to mesenchymal transition. EMT characteristics such as acquisition of mesenchymal markers and loss of epithelial markers were evident in the induction of vimentin and downregulation of E-cadherin and cytokeratins, as well as phenotypic alterations including increased contraction and enhanced mobility were detected.