Prostatic acid phosphatase (ACPP) (PAP)

Prostatic acid phosphatase (PAP), encoded by the ACPP gene, is a glycoprotein enzyme primarily synthesized in the glandular epithelium of the prostate (UniProt P15309). Its physiological roles include the dephosphorylation of macromolecules in seminal fluid and the regulation of nociception through the conversion of AMP to adenosine (PubMed: 19011627). In the context of oncology, PAP is highly overexpressed in prostate cancer cells, making it a prime candidate for targeted immunotherapy (PubMed: 24101518). The target functions as a tumor-associated antigen where its peptide fragments are presented on Major Histocompatibility Complex (MHC) molecules to T-cell receptors (TCRs). This interaction is exploited by Sipuleucel-T, an autologous cellular immunotherapy that primes dendritic cells with a PAP-GM-CSF fusion protein to activate T-cells against malignant prostate tissue (FDA: Provenge Label). Beyond cellular therapies, PAP is also the focus of DNA vaccines like pTVG-HP, which aim to induce long-term immune surveillance (ClinicalTrials.gov: NCT01341652). While serum PAP levels were historically used for diagnosis, its modern therapeutic value lies in its ability to serve as a specific target for cytotoxic T-lymphocyte induction. Safety concerns associated with targeting PAP include infusion-related reactions and the potential for autoimmune-mediated prostatitis (PubMed: 21460387).

Other names

Acid phosphatase 3Prostatic acid phosphomonoesteraseACPPPAPProstatic acid phosphatase

Induction of antigen-specific T-cell mediated cytotoxicity through the presentation of PAP-derived peptides on MHC molecules to T-cell receptors.