PSMA-targeted extracellular vesicles deliver siADAM9 to suppress tumor progression and enhance androgen-targeted therapy in prostate cancer

Aim: The progression of prostate cancer to metastatic and castration-resistant disease remains a major therapeutic challenge, and a disintegrin and metalloproteinase 9 (ADAM9) has emerged as a key regulator of tumor progression and adaptive androgen receptor signaling. We aimed to develop a prostate-specific membrane antigen (PSMA)-targeted extracellular vesicle (EV) platform for selective delivery of small interfering RNA (siRNA) against ADAM9 (siADAM9) and evaluate its therapeutic potential in prostate cancer. Methods: Mesenchymal stem cell (MSC)-derived EVs were engineered to display a PSMA-targeting single-chain variable fragment (PSMA-scFv). Targeting specificity and cellular uptake were evaluated in PSMA-expressing and PSMA-negative prostate cancer cells. Functional effects of EV-mediated siADAM9 delivery were assessed by proliferation, migration, and sphere formation assays in hormone-sensitive (LNCaP) and castration-resistant (CWR22Rv1) prostate cancer models. Gene and protein expression were analyzed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunoblotting. Therapeutic efficacy was further evaluated in combination with androgen deprivation therapy and abiraterone. Results: PSMA-scFv functionalization enabled selective EV binding and uptake in a PSMA-dependent manner. Through this targeting strategy, EV-mediated siADAM9 delivery effectively suppressed ADAM9 expression and inhibited malignant phenotypes, including proliferation, migration, and tumor sphere formation, while reversing epithelial-mesenchymal transition- and stemness-associated molecular programs. Moreover, EVs loaded with siADAM9 (EV-siADAM9) enhanced the efficacy of androgen-targeted therapy in both hormone-sensitive and castration-resistant prostate cancer models. These effects were associated with disruption of ADAM9 downstream signaling, including aldo-keto reductase family 1 member C3 (AKR1C3)-mediated androgen biosynthesis and cell-cycle regulation. Conclusion: These findings provide in vitro proof-of-concept that PSMA-targeted EVs preferentially deliver siADAM9, suppress tumor-promoting programs, and enhance androgen-targeted therapy, supporting further preclinical evaluation of this platform.