Immune profiling identifies the contribution of extracellular vesicles to immune modulation and progression in prostate cancer.

Prostate cancer is the fourth leading cause of death in men worldwide. Currently, the gold standard for PCa diagnosis remains the Prostate-Specific Antigen (PSA); therefore, there is a growing demand for novel diagnostic approaches for early prediction of aggressive types of prostate cancer. The complexity of tumors is further enhanced by the presence of extracellular vesicles (EVs). These membrane-enclosed spherical particles are directly derived from their parent cells with their information (mRNAs, non-coding RNAs, and proteins) and play a critical role in intercellular communication. However, the role of PCa EVs in the crosstalk between cancer cells and resident cells in the microenvironment is still under investigation. Different prostate cancer cell lines were cultured for 48 h in medium supplemented with FBS exo-free medium. Next, secreted EVs were separated using differential ultracentrifugation, and further EVs characterization was performed by nanoparticle tracking analysis, immunoblotting, and scanning electron microscopy. The effect of prostate cancer EVs on the immune cell population was analyzed after staining PBMCs using flow cytometry. Additionally, cytokines released into the conditioned media were evaluated using an ELISA assay. We illustrated how EVs from prostate cancer cells of different background variously affected immune cells and modulated the expression of several cytokines after 24 h of treatment. We observed that the number of rare monocytes, CD14 + CD16 + , was significantly reduced in PBMCs treated with PC-3 and DU 145 EVs compared with LNCaP EVs. Furthermore, CD4 + and CD8 + activated cells were significantly more responsive when PBMCs were treated with PC-3 EVs compared to LNCaP EVs. Subsequently, pro- and anti-inflammatory cytokines were found to be more abundant in samples treated with PC-3 and DU 145 EVs. This suggests a potential role of EVs in prostate cancer progression and immune system evasion. Our study provides preliminary evidence that prostate cancer EVs exert distinct immunomodulatory effects, depending on their cellular origin. Ultimately, the differences observed between PC-3 EVs, DU 145 EVs and LNCaP EVs highlight the potential use of immune cell markers as reliable indicators of disease progression and as a non-invasive tool to complement prostate cancer risk stratification strategies.