Transcriptome-wide gene expression analysis of prostate cancer (PCa) tissue specimen II

We assessed transcriptome-wide gene expression in tissue specimens of PCa patients who underwent radical prostatectomy (RP) by next-generation sequencing (HiSeq 2500). We applied Cox proportional hazard models to the cohorts from different platforms and specimen types and combined the evidence from these by fixed effect meta-analysis to identify genes predictive for time to DoD (death of disease). Genes were combined by a weighted median approach into a prognostic score. We stratified PCa patients according to seven clinical risk groups based on Gleason Score (GS), the presence of regional lymph node metastases (pN) and the occurrence of death of disease (DoD): (i) very low risk (group V: GS<7, pN0), (ii) low risk (group L: GS=7, pN0), (iii) medium risk (group M: GS<=7, pN1), (iv) high risk survivors without lymph node infiltration (group H-s: GS>7, pN0), (v) high risk non-survivors without lymph node infiltration (group H-d: GS>7, pN0, DoD), (vi) high risk survivors with lymph node infiltration (group H+s: GS>7, pN1), (vii) high risk non-survivors with lymph node infiltration (group H+d: GS>7, pN1, DoD). For high risk groups adjacent tumor-free prostate tissue samples were obtained (groups H+sf, H-sf, H+df, H+df). Information on the course of the disease, survival of the patients and the cause of death were obtained from the general practitioners or treating urologists or from records of the regional tumor registry. Clinicopathological parameters were obtained by routine histopathological examination of the surgical specimens. Serum levels of the prostate-specific antigen (PSA) were determined preoperatively (Abbott, Wiesbaden, Germany). Total RNA of RP-derived FFPE specimen of 13 PCa patients was assessed for gene expression profiling by strand-specific total RNASeq. Raw data not submitted to GEO due to patient privacy issues