Abstract 468: A novel gene therapy approach for treating prostate cancer through the overexpression of mutant androgen receptor

Abstract Prostate cancer is the second most common cancer in men and one of the leading cause of cancer related death. In metastatic prostate cancer androgen deprivation therapy (ADT) is the main treatment strategy. However within one to two years it progresses into castration resistant prostate cancer (CRPC) through various mechanisms including androgen receptor (AR) mutations and splicing variants. In this study we produced non-functioning AR gene incorporated into plasmid vector enabling constant amplification in mammalian cells. The reconstructed plasmid was encapsulated within PLGA nanoparticle which harboring PSMA antibody on its surfaces through PEGylation. The therapeutic effect of non-functioning AR amplification was evaluated in this study We developed AR gene sequence with 3 base pair deletion in DNA binding domain which confers non-functioning AR. The mutated AR was incorporated into plasmid vector under CMV promotor which enables constant amplification of non-functioning AR in mammalian cells. To enhance the delivery of the reconstructed plasmid to prostate cancer cells, PLGA nanoparticle was utilized. PLGA nanoparticle was PEGlyated with PSMA antibody on its surfaces. The reconstructed plasmid was contained in PSMA-PLGA nanoparticle (mAR-PSMA-PLGA). Prostate cancer celling 22Rv1 was used for the experiment and enzalutamide resistant 22Rv1 (EnzR-22Rv1) was produced through serial treatment of enzalutamide on 22Rv1 cells. Xenograft prostate cancer model was developed using nude mice and treatment effect was evaluated We confirmed the specificity of PSMA-PLGA nanoparticle on prostate cancer cells. When LNCaP prostate cancer cells were co-cultured myoblast cells, GFP producing PSMA-PLGA nanoparticle was treated. Only LNCaP cells were positive for GFP signal which means that PSMA-PLGA nanoparticle attaches to prostate cancer cells specifically. 22Rv1 cells were treated with mAR-PSMA-PLGA and showed constantly enhanced non-functioning AR production without activating subsequent genes including IGF1 and PSA. The mAR-PSMA-PLGA also suppressed proliferation of 22Rv1 and EnzR-22Rv1 cells. Furthermore in xenograft model using EnzR-22Rv1, mAR-PSMA-PLGA reduced tumor growth significantly and reversed enzalutamide resistance showing synergistic effect with enzalutamide treatment. PSMA-PLGA nanoparticle system efficiently deliver reconstructed plasmid in vitro and in vivo which enabling targeted gene therapy. Amplification of non-functioning AR using mAR-PSMA-PLGA significantly suppress tumor growth and diminishes enzalutamide resistance. Citation Format: Seung-hwan Jeong, Seokbong Hong, Hyeong Dong Yuk, Cheol Kwak. A novel gene therapy approach for treating prostate cancer through the overexpression of mutant androgen receptor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 468.