Diagnostic and prognostic value of T-cell receptor gamma alternative reading frame protein (TARP) expression in prostate cancer.

T-cell receptor gamma chain alternative reading frame protein (TARP) has recently been proposed as being up-regulated in prostate cancer (PCA). Additionally, TARP has been proposed as a potential therapeutic target for cancer therapy. We analysed the protein expression of TARP in a large well characterised prostate cancer cohort to assess its diagnostic and prognostic value. Methodologically, we constructed a tissue microarray comprising more than 600 PCA cases including matching benign prostate tissue. TARP protein expression was carefully analysed and associated with clinico-pathological parameters, PSA-relapse free survival and expression data of established and proposed diagnostic markers (AMACR, p63, GOLPH2). Our results show that TARP is significantly over-expressed in the vast majority (approximately 85%) of PCA in comparison to non neoplastic prostate tissue. Its expression was associated with conventional markers of unfavourable and more aggressive tumour behaviour. However, a prognostic value of TARP could not be found. The diagnostic value of TARP is limited in comparison to AMACR, p63 or GOLPH2. Since TARP specific immunologic therapy regimen are currently being tested, the high frequency of TARP over-expression in PCA conveys a high potential for a predictive and potentially therapeutic use of this biomarker.