Abstract B023: Targeting noncanonical Wnt5a signaling suppresses the neural lineage network and overcomes enzalutamide resistance in advanced prostate cancer

Abstract INTRODUCTION AND OBJECTIVES Androgen receptor (AR) blockade using antiandrogens is a mainstay for the treatment of castration-resistant prostate cancer (CRPC). However, resistance to antiandrogens occurs unavoidably due to the escaping mechanisms of tumor cells that are not completely understood. Upregulation of non-canonical Wnt ligand Wnt5a is identified from circulating tumor cells from CRPC patients after being treated with enzalutamide. FZD2, the cognate frizzled receptor for Wnt5a, is the most commonly co-upregulated non-canonical Wnt signaling molecule in prostate cancer. In this study, we determined the role of non-canonical Wnt5a/FZD2 to enzalutamide resistance and neural lineage plasticity, and explore the potential of targeting Wnt5a/FZD2 to overcome resistance in advanced prostate cancer. METHODS Wnt5a and FZD2 expression was determined in enzalutamide-resistant C4-2B MDVR cells. Wnt5a and FZD2 expressions were modulated using specific siRNAs. Cell growth, colony formation, and migration were studied in vitro. Transcriptomic analysis was performed on C4-2B MDVR cells treated with FZD2 knocked down; gene program of non-canonical Wnt signaling, hallmark androgen response and AR-V7 associated genes, and neural lineage pathways were analyzed. A novel tRNA bioengineered Wnt5a siRNA was developed to target Wnt5a/FZD2 signaling. The effect of tRNA-siWnt5a on tumor growth, sensitivity to enzalutamide treatment, and neural lineage plasticity was evaluated in vitro and in vivo. RESULTS Wnt5a and FZD2 are highly upregulated in castration-resistant prostate cancer patients, which is verified overexpression in enzalutamide-resistant C4-2B MDVR cells. Knocking down Wnt5a and FZD2 diminishes the enrichment of the non-canonical Wnt signaling pathway. Downregulating Wnt5a and FZD2 expression by specific siRNAs suppresses prostate cancer cell proliferation and resensitized C4-2B MDVR cells to enzalutamide treatment. Suppressing Wnt5a and FZD2 abrogated the enrichment of gene programs regulating cancer cell survival/proliferation, and neural lineage pathways including neuron differentiation and embryonic stem cell markers. Using the bioengineered tRNA-Wnt5a siRNA effectively inhibited the growth of enzalutamide-resistant prostate cancer cells and resensitized tumor cells to enzalutamide treatment in vitro, and resistant CRPC PDX LuCaP35CR tumor growth in vivo. Conclusions Our results suggest that activation of noncanonical Wnt5a/FZD2 signaling confers to enzalutamide resistance and neural lineage plasticity. Targeting the Wnt5a signal could provide benefits for CRPC patients with tumors expressing a high level of Wnt5a, FZD2, and lineage markers, not only enhancing the anti-tumor effects of enzalutamide but suppressing the potential of neuroendocrine differentiation in advanced prostate cancer patients. Citation Format: Shu Ning, Wei Lou, Chengfei Liu, Alan Paul Lombard, Leandro S. D' Abronzo, Neelu Batra, Aiming Yu, Christopher P. Evans, Allen Gao. Targeting noncanonical Wnt5a signaling suppresses the neural lineage network and overcomes enzalutamide resistance in advanced prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B023.