UC Davis

BACKGROUND/OBJECTIVE: Prostate cancer (PCa) remains a prevalent and deadly disease, particularly in its advanced stages. Despite various available treatments, resistance to drugs like enzalutamide continues to present significant challenges. This study aimed to investigate the role of Galectin-1 (Gal-1) in enzalutamide-resistant PCa and assess its potential as a therapeutic target to overcome resistance. METHODS: The study utilized specific siRNA-mediated knockdown of Gal-1 in enzalutamide-resistant PCa cells to evaluate its effects on cell proliferation and response to enzalutamide treatment. An orthotopic mouse model was employed to examine the in vivo impact of Gal-1 knockdown. Pharmacological targeting of Gal-1 was conducted using LLS30, and its effects were assessed both in vitro and in vivo. RNA sequencing (RNA-seq) analysis was performed to explore the molecular mechanisms underlying the observed effects. RESULTS: The findings demonstrated significant upregulation of Gal-1 in enzalutamide-resistant PCa cells. Gal-1 knockdown inhibited cell proliferation and resensitized resistant cells to enzalutamide treatment in the orthotopic mouse model. Elevated levels of androgen receptor full-length and AR-V7 are key mechanisms under-lying resistance to enzalutamide in PCa. Gal-1 knockdown suppressed AR and AR-V7 expression and their transcriptional activity. Treatment with LLS30 significantly suppressed the growth of enzalutamide-resistant PCa cells and exhibited synergistic effects when combined with enzalutamide. Notably, this combination therapy significantly inhibited the growth of enzalutamide-resistant xenografts in vivo. RNA-seq analysis revealed that LLS30 modulates AR and AR-V7 signaling through the inhibition of associated target genes. CONCLUSION: These findings highlight Gal-1 as a promising therapeutic target for overcoming enzalutamide resistance in PCa. Targeting the Gal-1/AR/AR-V7 axis with LLS30 presents a novel strategy to enhance enzalutamide efficacy and address drug resistance in advanced PCa.