Prostate‑specific membrane antigen: Molecular functions and emerging roles as a therapeutic target (Review).

The present review focuses on the molecular functions of prostate‑specific membrane antigen (PSMA) as a biologically active protein. Its clinical use as a positron emission tomography imaging marker or radioligand therapy target is beyond the scope of the current review. The role of PSMA (also known as folate hydrolase 1/glutamate carboxypeptidase II/N‑acetylated‑α‑linked acidic dipeptidase) has progressed from that of a prostate cancer biomarker to a functional driver of tumor biology. Structurally, PSMA is a type II transmembrane glycoprotein with glutamate carboxypeptidase and folate hydrolase activities, linking glutamate and one‑carbon metabolism to proliferation, redox balance and epigenetic regulation. PSMA undergoes clathrin‑dependent endocytosis and interacts with various scaffolding proteins, such as filamin A and receptor for activated C kinase 1, which are properties that underlie its functional role as a molecular signaling hub, in addition to being a therapeutic entry point. Its expression is dynamically regulated by androgen receptor signaling, NF‑κB activation and epigenetic modifiers, contributing to intra‑patient heterogeneity and treatment resistance. PSMA expression is not restricted to prostate epithelium but is also expressed in tumor‑associated endothelium across multiple malignancies, where it can promote angiogenesis through integrin/PI3K‑AKT‑mTOR signaling and paracrine induction by extracellular vesicles. These molecular functions can result in immune exclusion, stromal activation and neuronal interactions, positioning PSMA as a key regulator of the tumor microenvironment. Although PSMA‑targeted imaging and therapies have demonstrated substantial clinical utility, understanding the biological basis of the function of PSMA is essential for interpreting the heterogeneous clinical responses and for designing next‑generation therapeutic strategies in association with this protein. By integrating enzymatic activity, non‑enzymatic scaffold signaling and tumor microenvironmental regulatory information, the present review provides a functional framework in the PSMA biology field and discusses how these molecular properties can be leveraged to develop novel rational and effective PSMA‑targeted interventions.