Gene expression profile of biochemically recurrent prostate cancer

Prostate cancer (PCa) is the second most common solid tumor type in men with high mortality rates. This study specifically aimed at identification of molecular biomarkers of PCa showing clinically aggressive course of the disease. Transcriptome analysis of PCa cases with biochemical progression (BCR) and No-BCR cases was performed with human gene expression microarrays. Expression levels of the selected genes were validated by real-time PCR in two independent cohorts of PCa cases (N = 55 and N = 53) and non-cancerous control tissues (NPT; N = 12). Comparison of gene expression profile of BCR and No-BCR cases revealed significant changes in expression levels of 455 genes, and the vast majority of the genes were down-regulated in the recurrent PCa. Quantitative evaluation of gene expression levels identified down-regulation of MT1E and GPR52 expression and up-regulation of EZH2 as the specific biomarkers of PCa progression, but only MT1E expression retained the independent prognostic value in a multivariate model. Aberrant methylation of the two fragments of MT1E promoter was frequent (71% and 60%) in PCa tissues as compared to NPT (p < 0.001) and was significantly associated with decreased expression in one of the PCa cohorts (p < 0.050). In conclusion, the data of our study suggest epigenetic inactivation of MT1E expression as the specific feature of PCa showing the tendency to progress. Gene expression profile was analyzed in 8 PCa cases with BCR and compared to 8 BCR-free cases. No biological replicates were performed.