Extracellular vesicles as drivers of epithelial-mesenchymal transition and carcinogenic characteristics in normal prostate cells

There is increasing evidence that cancer dissemination and metastasis establishment may not only be due to the movement of tumor cells. Content of extracellular vesicles (EVs) secreted by tumor cells may also reflect the origin of these cells. Some molecules that constitute these EVs have already been used as targets for detection of specific tumors. However, to the best of our knowledge, EVs from biopsies and plasma have not yet been compared nor thoroughly investigated as triggers of malignant transformation and metastatic niche formation. To evaluate the role of EVs in the cellular microenvironment, we have treated the normal epithelial prostate cell lines, RWPE-1 and PNT-2, with a pool of EVs from biopsies of prostate primary tumors (bEVs), biopsies of benign prostate hyperplasia (hEVs), plasma of prostate cancer (PCa) patients (pEVs) or plasma of healthy individuals (pnEVs). Each of the four pools consisted of isolated EVs from several subjects, of which PCa patients were in different stages of cancer. Migration and proliferation profiles, cytokine release, and a panel of PCa-associated genes' expression of epithelial-mesenchymal transition in the cell lines were evaluated after 24h incubation with EVs. When compared to the control groups, cells treated with the pool of EVs isolated from tumor biopsies and plasma of PCa patients showed greater migration and proliferation, significant alterations in gene expression, and high levels of IL-8, factors that are associated with cancer development. Specifically, isolated bEVs and pEVs may induce malignant features in non-tumor cells by activating several cellular events associated with cancer progression, suggesting that future PCa therapy may target multiple elements found in tumor-derived EVs.