Microvesicles and epithelial mesenchymal transition in the development of cancer

Introduction: Microvesicles released by tumour cell lines are thought to play an important role in both extracellular matrix (ECM) invasion and the evasion of immune system. We have examined the role of MVs derived from a T cell line (Jurkat) on PNT2 cells (normal prostate cells) to see if they carry some bioactive molecules capable of inducing an epithelial to mesenchymal transition (EMT). Materials and methods: PNT2 cells (4x103) were seeded for 14hr in 12-well plates and cultured in complete growth medium. Cells were washed twice with RPMI and treated with 30 mg/ml of Jurkat cell-derived MVs (378C for 5 days). Changes in morphology and in expression of vimentin and E-cadherin by flow cytometry using the Guava EasyCyte and immunofluorescence microscopy (Olympus IX81 inverted microscope) were noted. Results: By microscopic analysis, PNT2 cells, which are of epithelial origin, treated with Jurkat MVs, showed some morphological changes. They became elongated, motile and morphologically mesenchymal-like as previously documented. The molecular changes were confirmed by immunohistochemical techniques using the fluorescencent microscope and flow cytometer. The experimental (MV-treated cells) compared to control (untreated cells) expressed high levels of mesenchymal markers such as vimentin and low levels of epithelial markers such as E-Cadherin. Proteins from PNT2 control cells and MV-treated cells were profiled by SDSPAGE for identification by mass spectrometry. Conclusions: The correlation between EMT and malignancy has been well documented in almost all carcinomas of epithelial origin. EMT basically explains how epithelial tumour cells can escape from primary residence, travel to distant sites and establish secondary tumours? Our work is the first report of EMT on normal prostate cell lines induced by microvesicles.