Isolation of prostate cancer-related exosomes.

Background/Aim: Exosomes have been demonstrated to be useful non-invasive biomarkers for several cancers including prostate cancer. Since normal cells also secrete exosomes, isolation of cancer-derived exosomes from blood is a prerequisite for their better understanding. The aim of this study is to establish the method for isolation of prostate cancer-related exosomes from blood. Materials and Methods: Exosomes were collected from prostate cancer LNCaP and PC-3 cell lines by ultracentrifugation and by using magnetic beads conjugated with anti-CD9 antibody and anti-prostate-specific membrane antigen (PSMA) antibody. Prostate cancer-related exosomes were also isolated from the plasma of prostate cancer patients by anti-PSMA beads. Isolated exosomes were analyzed by western blotting. Results: Exosomes were isolated from LNCaP cells by ultracentrifugation, contained PSMA and androgen receptor (AR). AR was also detected in exosomes isolated from LNCaP cells by anti-PSMA and anti-CD9 beads, showing that AR is present in prostate cancer-related exosomes. The amount of CD9 in isolated exosomes was much higher in advanced and chemo-resistant prostate cancer patients than in prostate cancer patients without metastasis and healthy volunteers, indicating that patients with aggressive prostate cancer exhibit higher levels of prostate cancer-related exosomes in blood. Conclusion: The immunoaffinity-based method we developed is capable of isolating prostate cancer-related exosomes from blood, the use of which will enhance investigation processes on exosomes in prostate cancer.