Prostate extracellular vesicles in patient plasma as a liquid biopsy platform for prostate cancer using nanoscale flow cytometry

Abstract

BackgroundExtracellular vesicles released by prostate cancer present in seminal fluid, urine, and blood may represent a non-invasive means to identify and prioritize patients with intermediate risk and high risk of prostate cancer. We hypothesize that enumeration of circulating prostate microparticles (PMPs), a type of extracellular vesicle (EV), can identify patients with Gleason Score≥4+4 prostate cancer (PCa) in a manner independent of PSA.Patients and MethodsPlasmas from healthy volunteers, benign prostatic hyperplasia patients, and PCa patients with various Gleason score patterns were analyzed for PMPs. We used nanoscale flow cytometry to enumerate PMPs which were defined as submicron events (100-1000nm) immunoreactive to anti-PSMA mAb when compared to isotype control labeled samples. Levels of PMPs (counts/μL of plasma) were also compared to CellSearch CTC Subclasses in various PCa metastatic disease subtypes (treatment naïve, castration resistant prostate cancer) and in serially collected plasma sets from patients undergoing radical prostatectomy.ResultsPMP levels in plasma as enumerated by nanoscale flow cytometry are effective in distinguishing PCa patients with Gleason Score≥8 disease, a high-risk prognostic factor, from patients with Gleason Score≤7 PCa, which carries an intermediate risk of PCa recurrence. PMP levels were independent of PSA and significantly decreased after surgical resection of the prostate, demonstrating its prognostic potential for clinical follow-up. CTC subclasses did not decrease after prostatectomy and were not effective in distinguishing localized PCa patients from metastatic PCa patients.ConclusionsPMP enumeration was able to identify patients with Gleason Score ≥8 PCa but not patients with Gleason Score 4+3 PCa, but offers greater confidence than CTC counts in identifying patients with metastatic prostate cancer. CTC Subclass analysis was also not effective for post-prostatectomy follow up and for distinguishing metastatic PCa and localized PCa patients. Nanoscale flow cytometry of PMPs presents an emerging biomarker platform for various stages of prostate cancer.

Extracellular Thimet Oligopeptidase is Released with Extracellular Vesicles from Human Prostate Cancer Cells

“…Studies have shown that EVs released by cancer cells appear to play an important role in tumor progression, diagnosis, and therapeutic potential [36][37][38] . The role played by a number of TOP-specific substrates in the proliferation of prostate cancer cells is a topic of interest in cancer research.…”

Extracellular Vesicles as Signaling Mediators and Disease Biomarkers across Biological Barriers

“…To avoid sample dehydration, cryogenic EM techniques have been developed, of which cryogenic TEM (cryo-TEM) is the most appropriate [137] (Figure 1). Atomic Force Microscopy (AFM), which is also used [138,139], provides information about specific properties, such as EV stiffness and elasticity [140]. While EM and AFM resolve the size of individual EVs, dynamic light scattering (DLS) is used to determine the collective mobility (diffusion coefficient) of the scattering vesicles.…”

Liquid biopsies: tumour diagnosis and treatment monitoring

“…The results showed that PMP levels in the plasma are far more effective than CTC subclasses in distinguishing PCa patients with different risks and prognostic factors. Moreover, PMP levels demonstrated the prognostic potential for clinical follow-up and could be used independently of PSA levels (Biggs et al, 2016). Activated platelets contain numerous growth factors such as platelet-derived growth factor (PDGF), transforming growth factor beta (TGFb), insulin-like growth factor (IGF)-1, basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF).…”