Identification of differentially expressed genes by serial analysis of gene expression in human prostate cancer

Prostate cancer is the leading cause of cancer death in American males. To better understand the genetic bases of this disease, we have generated a comprehensive molecular profile of human prostate. The gene expression pattern in normal and prostate cancer tissues was analyzed by serial analysis of gene expression (SAGE). A total of 133,217 transcripts were analyzed, and 35,185 distinct SAGE tags were identified representing 19,287 genes. Comparison of the transcripts in normal and tumor tissue revealed 156 differentially expressed genes (P < 0.05), of which 88 genes were up-regulated and 68 genes were down-regulated in the tumor tissue. Based on SAGE data, we estimate that the transcriptome for human prostate is approximately 37,000. Several differentially expressed genes identified by SAGE were selected for confirmation using immunohistochemistry. Some genes (e.g., E2F4) were overexpressed in tumor epithelial cells and some (e.g., Daxx) were increased in tumor stroma. Further characterization of the role of E2F4 and Daxx as well as other differentially expressed genes may provide useful insights into the mechanism of prostate cancer development.