Abstract A016: Prostate cancer–derived extracellular vesicles reprogram bone microenvironment cells to enhance monocyte migration

Abstract Prostate cancer (PCa) affects 1. 4 million men annually and remains the fifth leading cause of cancer-related deaths in men. Despite approximately 95% five-year survival following primary treatment, up to 40% of patients experience recurrence due to metastatic spread, often driven by dormant micrometastases. Extracellular vesicles (EVs) are lipid bilayer–enclosed particles (50–5000 nm) that mediate intercellular communication by transferring molecular cargo between cells. This study investigates how PCa-derived EVs from the aggressive PC3 cell line influence cells within the bone microenvironment (BME). EVs were isolated by differential and iodixanol gradient ultracentrifugation and validated according to MISEV2023 guidelines. Nanoparticle tracking analysis confirmed small EVs with a mean diameter of 242. 6 ± 2. 2 nm, and Western blotting verified EV markers CD63, CD147, Cav1, and TSG101, establishing a robust workflow for EV isolation and characterization. PC3-derived EVs were co-cultured with BME cell lines to assess tumor-promoting potential. EVs were labeled with carboxyfluorescein diacetate (CFDA), a fluorescent dye for tracking uptake. Flow cytometry confirmed interaction with THP-1 monocytes, showing both surface binding and internalization. Transwell migration assays showed that conditioned media (CM) from THP-1 cells exposed to PC3 EVs significantly increased THP-1 migration compared with CM from untreated cells (p = 0. 0132; two-way ANOVA with Tukey’s post hoc test). These results suggest that PC3-derived EVs do not act as chemoattractants directly but reprogram THP-1 cells to release factors that promote migration. Ongoing studies are testing whether similar effects occur in other BME cell types. These findings indicate that prostate cancer–derived EVs actively modulate bone microenvironment cell behavior and may facilitate premetastatic niche formation during PCa progression. Future work will adapt these methods to patient-derived explants (PDEs), offering a more physiologically relevant model to investigate the role of EVs in PCa bone metastasis. These models will provide novel insights into early metastatic events and may guide the development of new monitoring tools and therapeutic strategies to disrupt EV-mediated communication and prevent PCa recurrence. Citation Format: Kate E. Duffy, Antoinette S. Perry, Margaret Mc Gee. Prostate cancer–derived extracellular vesicles reprogram bone microenvironment cells to enhance monocyte migration abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Prostate Cancer Research and Treatment; 2026 Jan 20-22; Philadelphia PA. Philadelphia (PA): AACR; Cancer Res 2026;86 (2Suppl): Abstract nr A016.