Persistenceofexpressionofthe TMPRSS2:ERGfusiongeneafter pre-surgeryandrogenablationmaybeassociatedwithearly prostatespecificantigenrelapseofprostatecancer: Preliminaryresults

Background: The recently identified TM- PRSS2:ERG fusion gene is a candidate oncogene for prostate cancer (PCa). Subjects and methods: We have tested for the presence of this gene in tumor samples from 84 patients who hadradicalprostatectomyin1998-2000.Sixtypatients(group A) had surgery only; 24 patients (group B) received androgen ablation therapyfor 3 monthsbefore surgery.Theoccurrence of the rearrangement was evaluated by RT-PCR and by fluo- rescent in situhybridization analysis. Results:A TMPRSS2:ERG fusion gene was present and expressed, as demonstrated by RT-PCR, in 84% of patients in group A and in 54% of patients in group B (p=0.01). The presence of TMPRSS2:ERG tran- scripts and the levels of ERG RNA, measured by quantitative Real Time-PCR, did not correlate significantly with clinical and pathologic characteristics of the tumors. In patients of group A,butnotinthoseofgroupB,ERGexpressionshowedaneg- ative correlation with the Gleason score (p=0.0001). Histo- chemical analysis showed that ERG expression is limited to tumor cells, and in group A patients (but not in group B pa- tients)itislimitedtothoseglandsthatexpress TMPRSS2:ERG. Conclusion: The lower proportion of patients expressing TM- PRSS2:ERG in group B suggests that androgen ablation in- hibitstheexpression of TMPRSS2:ERG.Moreover, ingroupB, but not in group A, patients with expression of the fusion gene had earlier prostate specific antigen recurrence (p=0.007). Although preliminary, the data indicate that tu- mors in which pre-surgeryandrogen ablation fails to suppress expressionofthefusiongenehaveahigherriskofrecurrence. (J. Endocrinol. Invest. 32: 590-596, 2009) ©2009, Editrice Kurtis