PGAP3 and posterior cortical atrophy: Functionally, PGAP3 silencing significantly impaired proliferation, clonogenic growth, and migration <i>in vitro</i>.<h4>Conclusion</h4>Our findings identify PGAP3 as a tumor-intrinsic gene associated with metabolic reprogramming and a CTL/CD8<sup>+</sup>-low immune contexture in PCa, supporting PGAP3 as a potential marker of the immune-cold tumor microenvironment and motivate future mechanistic studies in immunocompetent systems.