The Prostate 70:70 ^78 (2010) Differential Expression of PCA3 and Its Overlapping PRUNE2 Transcriptin Prostate Cancer Maciej Salagierski, 1,2 Gerald W. Verhaegh, 1,3 Sander A. Jannink, 4 Frank P. Smit, 4 Daphne Hessels, 4 and Jack A. Schalken 1,3 * 1 Department of Urology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands 2 1st Urology Department, Medical University of L - o¤ dz¤ ,L - o¤ dz¤ ,Poland 3 Nijmegen Centre for Molecular Life Sciences, Nijmegen, the Netherlands 4 NovioGendix, Nijmegen, the Netherlands BACKGROUND. PCA3 is one of the most prostate cancer (PrCa)-specific markers described so far. Recently, a new genomic structure of PCA3 as well as new flanking and overlapping gene transcripts has been identified. Furthermore, a co-regulation of PCA3 and its overlapping gene PRUNE2(BMCC1) has been suggested. Our aim was to assess the diagnostic performance of a new PCA3 isoform (PCA3-TS4) and to study the interactions between PCA3 and BMCC1 in PrCa. METHODS. We used SYBR Green quantitative (q)PCR with specific primers to compare PCA3 and BMCC1 expression of normal versus tumor tissue of human prostate. PCA3-TS4 plasmid was created to calculate the absolute amounts of PCA3 transcripts. The androgen regulation of PCA3 and BMCC1 expression was studied in LNCaP and 22Rv1 cells stimulated with 5a-dihydrotestosterone. RESULTS. We have not found any relevant diagnostic advantage of the PCA3-TS4 isoform over the ‘‘classical’’ PCA3 isoform in our group of PrCa patients. Additionally, PCA3-TS4 appears to be only a minor PCA3 transcript. We were also unable to confirm the hypothesis that BMCC1 isoforms are androgen-induced in vitro. CONCLUSIONS. Despite the presence of the recently identified marginal PCA3 transcripts in human PrCa, the previously described major PCA3 isoform still constitutes the best target for diagnostic purposes. PCA3 and BMCC1 are overlapping genes in reverse orientation that do not appear to be co-regulated. Prostate 70: 70–78, 2010. # 2009 Wiley-Liss, Inc. KEY WORDS: prostate cancer; diagnosis; PCA3; PRUNE2(BMCC1); gene regulation INTRODUCTION Due to the increasing overall life expectancy, the incidence of prostate cancer (PrCa) is rising steadily. Currently, PrCa constitutes the most common cancer in men and second leading cause of cancer death in the United States affecting on average one in six men during their lifetime [1]. In screened populations most of the detected prostate malignancies are clinically indolent, that is, not leading to a cancer-specific death. Nevertheless, some prostate tumors possess a highly aggressive phenotype. Unfortunately, standard diag- nostic tools including universally used serum prostate- specific antigen (PSA) are not cancer-specific enough and are also unable to discriminate between clinically insignificant and aggressive disease or to predict PrCa Additional Supporting Information may be found in the online version of this article. Abbreviations: CR-PrCa, castration-resistant PrCa; DHT, 5a-dihy- drotestosterone; NPr, normal prostate; BPH, benign prostatic hyperplasia; HG-PrCa, high-grade PrCa; LG-PrCa, low-grade PrCa; Met-PrCa, metastatic PrCa; ORF, open-reading frame; PCA3, prostate cancer gene 3; PrCa, prostate cancer; RP, radical prostatec- tomy; TURP, transurethral resection of the prostate; RT-PCR, reverse transcription polymerase chain reaction; GS, Gleason score. Grant sponsor: European Association of Urology (EAU); Grant number: S-02-2008. *Correspondence to: Jack A. Schalken, 267 Experimental Urology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands. E-mail: j.schalken@uro.umcn.nl Received 17 June 2009; Accepted 3 August 2009 DOI 10.1002/pros.21040 Published online 16 September 2009 in Wiley InterScience (www.interscience.wiley.com). ß 2009 Wiley-Liss,Inc.