Abstract B035: CCT as a Driver of Prostate Cancer Invasion and Resistance: A New Therapeutic Target

Abstract Background: Prostate cancer (PCa) is the second leading cause of cancer-related death in men worldwide, with over 1. 4 million new cases annually. Standard treatment for advanced disease includes androgen deprivation therapy (ADT), yet most patients progress to metastatic castration-resistant PCa (CRPC), where the 5-year survival rate falls below 30%. Current therapies targeting androgen receptor (AR) signaling or chemotherapy offer limited benefit, underscoring the need for novel strategies. Emerging data from castration-sensitive PCa (CSPC) and CRPC (unpublished) suggest that genomic instability increases during progression to CRPC, driving tumor heterogeneity and therapy resistance. The mechanisms underlying these changes remain poorly defined. We investigated the role of Chaperonin-Containing TCP-1 (CCT/TRiC), a protein-folding chaperone, in this process. Genomic instability during oncogenesis increases the production of misfolded proteins, potentially making CCT essential for PCa survival and adaptation under therapeutic stress. Methods: CCT is an eight-subunit complex (CCT1–8). Prior work identified the CCT2 subunit as critical for chaperonin oncogenic activity. Using PCa cell lines (LNCaP, PC3, 22Rv1), we depleted CCT2 via inducible small hairpin RNA (shRNA) and expressed FLAG-tagged CCT2 via lentiviral transduction. To therapeutically inhibit CCT, we developed an amphipathic peptide that targets the ATP-binding and oligomerization sites of CCT subunits and formulated a cell-permeable micellar version, Zwitterion-TRiC Off Peptide (Z-TOP). Functional assays assessed viability, proliferation, migration, and spheroid growth. Extracellular vesicles (EVs) released from PCa were isolated and characterized by nanoparticle tracking analysis (NTA) and flow cytometry. Transcriptomic profiling (RNA-seq) and pathway enrichment analysis were performed following CCT2 depletion or Z-TOP treatment. Results: CCT2 depletion or overexpression significantly altered PCa cell viability, growth, and migration. Z-TOP treatment produced similar effects, reducing viability, proliferation, migration, and spheroid size. Transcriptomic analysis revealed overlapping and distinct gene expression changes to cell cycle regulation, cancer signaling, and lipid pathways. EV studies indicated that CCT contributes to EV biogenesis; CCT2 mRNA and protein were detected in EV cargo. Both CCT2 depletion and Z-TOP treatment disrupted EV release and composition, potentially impairing metastatic signaling. Conclusions: CCT regulates PCa cell behavior and intercellular communication locally and via EVs, promoting hormone resistance and metastasis. These findings position CCT as a promising therapeutic target in advanced PCa. Z-TOP demonstrates potential for inhibiting metastasis and improving outcomes in CRPC. Future studies will evaluate Z-TOP in vivo and explore combination strategies with AR-targeted agents. Microsoft Co-Pilot was used to edit the text. Citation Format: Annette R. Khaled, Carolyn Dang, James Velazquez, Matthew Counts, Lorraine Leon, Sally Litherland, Shoba Kankipati, Priya Gopalan. CCT as a Driver of Prostate Cancer Invasion and Resistance: A New Therapeutic Target 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 B035.