Isolation of Plasma Extracellular Vesicles for High-Depth Analysis of Proteomic Biomarkers in Metastatic Castration-Resistant Prostate Cancer Patients

Ali T Arafa; Megan Ludwig; Onur Tuncer; Lily Kollitz; Ava Gustafson; Ella Boytim; Christine Luo; Barbara Sabal; Daniel Steinberger; Yingchun Zhao; Scott M Dehm; Zuzan Cayci; Justin Hwang; Peter W Villalta; Emmanuel S Antonarakis; Justin M Drake

doi:10.3390/cancers16244261

Isolation of Plasma Extracellular Vesicles for High-Depth Analysis of Proteomic Biomarkers in Metastatic Castration-Resistant Prostate Cancer Patients

Cancers (Basel). 2024 Dec 21;16(24):4261. doi: 10.3390/cancers16244261.

Authors

Ali T Arafa^{1

2}, Megan Ludwig², Onur Tuncer³, Lily Kollitz³, Ava Gustafson¹, Ella Boytim¹, Christine Luo¹, Barbara Sabal³, Daniel Steinberger³, Yingchun Zhao^{1

4}, Scott M Dehm^{1

5

6}, Zuzan Cayci³, Justin Hwang^{1

7}, Peter W Villalta^{1

4}, Emmanuel S Antonarakis^{1

7}, Justin M Drake^{1

2

6}

Affiliations

¹ Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA.
² Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA.
³ Nuclear Medicine Division, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
⁴ Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
⁵ Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA.
⁶ Department of Urology, University of Minnesota, Minneapolis, MN 55455, USA.
⁷ Division of Hematology/Oncology and Transplantation, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.

Abstract

Introduction: Prostate cancer treatment has been revolutionized by targeted therapies, including PARP inhibitors, checkpoint immunotherapies, and PSMA-targeted radiotherapies. Despite such advancements, accurate patient stratification remains a challenge, with current methods relying on genomic markers, tissue staining, and imaging. Extracellular vesicle (EV)-derived proteins offer a novel non-invasive alternative for biomarker discovery, holding promise for improving treatment precision. However, the characterization of plasma-derived EVs in prostate cancer patients remains largely unexplored. Methods: We conducted proteomic analyses on EVs isolated from plasma in 27 metastatic castration-resistant prostate cancer (mCRPC) patients. EVs were purified using ultracentrifugation and analyzed via mass spectrometry. Proteomic data were correlated with clinical markers such as serum prostate-specific antigen (PSA) and bone lesion counts. Statistical significance was assessed using Mann-Whitney t-tests and Spearman correlation. Results: The median age of patients was 74 (range: 44-94) years. At the time of blood collection, the median PSA level was 70 (range: 0.5-1000) ng/mL. All patients had bone metastasis. A total of 5213 proteins were detected, including EV-related proteins (CD9, CD81, CD63, FLOT1, TSG101) and cancer-related proteins (PSMA, B7-H3, PD-L1). Proteomic profiling of plasma EVs revealed a significant correlation between specific EV-derived proteins and clinical prognostic markers. B7-H3, LAT1, and SLC29A1 showed a strong association with serum PSA levels and number of bone lesions, indicating potential for these proteins to serve as biomarkers of disease burden and therapy response. Conclusions: Our findings demonstrate the potential of EV-based proteomics for identifying biomarkers in mCRPC patients. Proteins such as B7-H3 and LAT1 could guide precision oncology approaches, improving patient stratification. Future research incorporating outcomes data and EV subpopulation analysis is needed to establish clinical relevance.

Keywords: B7-H3; PSMA; extracellular vesicles; prostate cancer; proteomics.

Abstract

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