Loss of PSP94 expression is associated with early PSA recurrence and deteriorates outcome of PTEN deleted prostate cancers

摘要

Objective: Prostate secretory protein of 94 amino acids(PSP94) is a target gene of the EZH2 transcriptional repressor and is often downregulated in prostate cancer;however, its prognostic value is disputed.Methods: Immunohistochemical analysis of a tissue microarray of 12, 432 prostate cancer specimens was performed to evaluate PSP94 expression. Correlation of PSP94 expression with tumor phenotype, patient prognosis, TMPRSS2:ERG fusion status, EZH2 expression and PTEN deletion was studied.Results: PSP94 expression was increased in benign prostatic hyperplasia;however, it was downregulated in 48% and negative in42% of the 9, 881 interpretable prostate cancer specimens. The loss of PSP94 expression was inversely correlated to EZH2 expression(P < 0.0001) and largely unrelated to the ERG status, but strongly correlated with high Gleason grade, advanced tumor stage, and nodal metastasis(P <0.0001 each). The fraction of PSP94-negative cancer specimens increased from 40% in pT2 to 52%in pT3 b-pT4(P < 0.0001) and from 40% in Gleason 3+3 = 6 to 46% in Gleason 4+3 = 7 and 60% in Gleason ≥4+4 = 8(P <0.0001). Loss of PSP94 was linked to early prostate-specific antigen recurrence, but with little absolute effect(P < 0.0001).However, it provided additional prognostic impact in cancer specimens with PTEN deletion. Loss of PSP94 deteriorated prognosis of cancer patients with PTEN deletion by more than 10%(P < 0.0001). The combination of PTEN deletion and PSP94 loss provided independent prognostic information that was observed in several subgroups defined by classical and quantitative Gleason grade.Conclusions: The results of our study suggest that combined PSP94/PTEN analysis can be potentially used in the clinical prognosis of prostate cancer.