A1 Refereed original research article in a scientific journal
Prostatic acid phosphatase is not a prostate specific target
Authors: Quintero IB, Araujo CL, Pulkka AE, Wirkkala RS, Herrala AM, Eskelinen EL, Jokitalo E, Hellstrom PA, Tuominen HJ, Hirvikoski PP, Vihko PT
Publisher: AMER ASSOC CANCER RESEARCH
Publication year: 2007
Journal: Cancer Research
Journal name in source: CANCER RESEARCH
Journal acronym: CANCER RES
Volume: 67
Issue: 14
First page : 6549
Last page: 6554
Number of pages: 6
ISSN: 0008-5472
DOI: https://doi.org/10.1158/0008-5472.CAN-07-1651
Abstract
Prostatic acid phosphatase (PAP) is currently evaluated as a target for vaccine immunotherapy of prostate cancer. This is based on the previous knowledge about secretory PAP and its high prostatic expression. We describe a novel PAP spliced variant mRNA encoding a type I transmembrane (TM) protein with the extracellular NH2-terminal phosphatase activity and the COOH-terminal lysosomal targeting signal (Yxx Phi). TM-PAP is widely expressed in nonprostatic tissues like brain, kidney, liver, lung, muscle, placenta, salivary gland, spleen, thyroid, and thymus. TM-PAP is also expressed in fibroblast, Schwarm, and LNCaP cells, but not in PC-3 cells. In well-differentiated human prostate cancer tissue specimens, the expression of secretory PAP, but not TM-PAP, is significantly decreased. TM-PAP is localized in the plasma membrane-endosomal-lysosomal pathway and is colocalized with the lipid raft marker flotillin-1. No cytosolic PAP is detected. We conclude that the wide expression of TM-PAP in, for instance, neuronal and muscle tissues must be taken into account in the design of PAP-based immunotherapy approaches.
Prostatic acid phosphatase (PAP) is currently evaluated as a target for vaccine immunotherapy of prostate cancer. This is based on the previous knowledge about secretory PAP and its high prostatic expression. We describe a novel PAP spliced variant mRNA encoding a type I transmembrane (TM) protein with the extracellular NH2-terminal phosphatase activity and the COOH-terminal lysosomal targeting signal (Yxx Phi). TM-PAP is widely expressed in nonprostatic tissues like brain, kidney, liver, lung, muscle, placenta, salivary gland, spleen, thyroid, and thymus. TM-PAP is also expressed in fibroblast, Schwarm, and LNCaP cells, but not in PC-3 cells. In well-differentiated human prostate cancer tissue specimens, the expression of secretory PAP, but not TM-PAP, is significantly decreased. TM-PAP is localized in the plasma membrane-endosomal-lysosomal pathway and is colocalized with the lipid raft marker flotillin-1. No cytosolic PAP is detected. We conclude that the wide expression of TM-PAP in, for instance, neuronal and muscle tissues must be taken into account in the design of PAP-based immunotherapy approaches.
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