Chemical Affinity Capture of Plasma Extracellular Vesicles Enables Efficient and Large-Scale Proteomic Identification of Prostate Cancer Biomarkers

The
serum prostate-specific antigen (PSA) testing is widely used
for prostate cancer (PCa) screening but suffers from poor specificity,
leading to unnecessary biopsies and overtreatment. The significant
potential of extracellular vesicles (EVs) in cancer diagnosis has
driven the development of efficient methods to isolate and identify
EV biomarkers from large-scale clinical samples. Here, we systematically
evaluate five commonly used EV isolation techniques through proteomic
profiling of plasma-derived EVs, endorsing TiO2-based chemical
affinity capture as a superior approach for analyzing EVs from complex
clinical samples. This method demonstrates exceptional advantages
in speed, throughput, reproducibility, and protein coverage. Using
this optimized workflow, we analyzed plasma EVs from 80 patients with
PCa and benign prostatic hyperplasia (BPH), identifying growth differentiation
factor 15 (GDF15) as a compelling biomarker with a predictive power
(AUC) of 0.908 for PCa. Extensive validation across independent cohorts
comprising 457 samples, including plasma EVs and prostate tissues,
confirmed GDF15’s ability to distinguish PCa from BPH and stratify
PCa stages. Notably, the combination of GDF15 with PSA further enhanced
diagnostic efficiency, particularly for patients in the PSA diagnostic
gray zone. This study establishes a robust workflow for EV protein
analysis in large clinical cohorts and highlights EV-GDF15 as a promising
biomarker for noninvasive PCa diagnosis.