Multicolor Flow Cytometric Analysis of Cancer-Derived Microvesicles Reveals a Unique Subpopulation Ratio in Plasma From Prostate Cancer Patients


Jorge L Schettini, Mukesh Maheshwari, Krunal Desai, Brian Rhees and David B. Spetzler


Circulating microvesicles (cMV) are membrane-bound cellderived structures that can be isolated from many biofluids and culture media. Previous studies have shown that cMVs are released by several cell types including immunocytes, endothelial, embryonic, tumor cells and also platelets. cMVs in blood are a source of potential biomarkers of disease diagnosis and progression. The purpose of this study was to determine whether exposed biomarkers on the surface of cMVs from processed plasma could distinguish prostate cancer from atypia, high grade prostatic intraepithelial neoplasia (HGPIN), benign or prostate inflammation. Isolated cMVs from the blood of biopsy-positive cancer patients were stained with a panel of specific antibodies to compare
phenotype, frequency and marker expression. Samples were collected prospectively prior to biopsy. The distribution of the cohort included 80 men with previously undiagnosed prostate cancer, 13 men with previously diagnosed prostate cancer (active surveillance), 6 atypia, 23 HGPIN, 28 inflammation, 49 benign and 25 normal samples. The cMVs from these patients were analysed by flow cytometry. Subpopulations of cMVs were determined based on the expression of multiple combinations of markers through proper gating. A systematic analysis of all potential biomarkers combinations showed a significant EpCAM positive subpopulation of cMVs in prostate cancer samples (current biopsy) and HGPIN/Atypia over other conditions. These results demonstrate that isolated cMVs from plasma can be used to determine relevant subpopulations in prostate cancer diagnosis.

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