Differential expression of PCA3 and its overlapping PRUNE2 transcript in prostate cancer.

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 5alpha-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.