Prostate Cancer Biomarkers with a Focus on Galectin-3: Emerging Clinical and Therapeutic Implications

Prostate cancer (PCa) management has evolved with biomarker-driven strategies, yet biological heterogeneity, adaptive resistance, and an immunosuppressive microenvironment limit their efficacy. Galectin-3 (Gal-3) has emerged as a central node in PCa pathobiology, influencing tumor survival, metastasis, and immune escape. This review comprehensively reviews Gal-3’s dual role as a biomarker and a therapeutic target. We first delineate the limitations of the current diagnostic, prognostic, and predictive biomarkers in PCa, establishing the unmet need. We then elucidate the multifunctional biology of Gal-3, detailing its compartment-specific roles in anti-apoptosis, angiogenesis, epithelial-to-mesenchymal transition, and, notably, its function as a master regulator of immunosuppression. The interaction between Gal-3 and prostate-specific antigen (PSA) is explored as a key regulatory interface. Furthermore, we catalog and analyze emerging Gal-3-targeted therapies, emphasizing their rationale for combination with immune checkpoint blockade to reverse therapeutic resistance. Finally, we outline a translational roadmap, advocating for standardized Gal-3 biomarker assays and biomarker-enriched clinical trials. Integrating Gal-3 into the PCa precision medicine toolkit offers a novel strategy to address heterogeneity and improve therapeutic durability.