DNA damage induced cellular senescence and it's PTEN-armed exosomes-the warriors against prostate carcinoma cells.

Exosomes are one type of small extracellular vesicles (EVs) having a size range of 30-150 nm and secreted by the endosomal compartment of most eukaryotic cells. It has been found that exosomes (EVs) can serve as a communicating vehicle to transfer information among cells and thus can be associated with numerous physiological and pathological functions. In this study, we have isolated exosomes (EVs) from two different human cancer cell lines. Isolated exosomes (EVs) were characterized by scanning electron microscopy, nanoparticle tracking analysis, DLS, and by western blotting. It was observed that exosomes (EVs) isolated from mock-treated human lung epithelial carcinoma (A549) cells or HeLa cells exerted growth arrest to the human prostate carcinoma (PC3) cells, but no growth arrest was observed in case of normal human lung fibroblast cell line (WI-38). Additionally, exosomes (EVs) isolated from PC3 cells have no effect on PC3 cells. This is also true for exosomes (EVs) isolated from H2O2-induced senescent human lung cancer cells (A549). Analysis of exosome (EVs) content by western blotting reveals the presence of PTEN in the exosome (EVs) of lung cancer cells. Functional analysis of PTEN pathways in PC3 cells indicates the inactivation of Akt in exosome (EV)-treated cells. Therefore, from our study we have concluded that exosomes (EVs) secreted from A549 cells which contain functional PTEN may be used for delivery of PTEN to cancer cells without functional PTEN.