Comprehensive gene expression microarray analysis of Ets-1 blockade in PC3 prostate cancer cells and correlations with prostate cancer tissues: Insights into genes involved in the metastatic cascade

Ets-1 is the prototype of the ETS family of transcription factors and is suggested to play an important role in the malignant progression of prostatic carcinomas. Therefore, in this study we investigated the effect of blocking Ets-1 in PC3 prostate cancer cells on genes involved in the metastatic cascade, and correlated these findings with prostate cancer tissues. Two stable PC3 cell cultures were established by transfection with either an Ets-1 inverse antisense expression vector or a mock control vector. The effect of blocking Ets-1 on genes involved in the metastatic cascade was assessed by a comprehensive gene expression microarray analysis of Ets-1 inverse and mock control cells. Correlating the sets of genes found in the PC3 microarray data with prostate cancer tissues was performed by verifying the genes in a comprehensive gene expression microarray analysis of RNA extracted from laser microdissected normal prostate glands and from carcinoma glands taken from prostate cancer patients. Western blot analysis confirmed the presence of Ets-1 in mock cells and its absence in Ets-1 inverse cells. In the Ets-1 blockade microarray, many differentially expressed genes were found; however, only genes with a greater than 10-fold up- or down-regulation between the Ets-1 blockade and mock control were considered significant. The genes were placed into four groups that play a role in the so-called metastatic cascade based on their known functions in proliferation, apoptosis, migration and angiogenesis. The genes found in the Ets-1 blockade microarray analysis were verified for their presence in the microarray analysis of prostate cancer tissues. Genes found in the microarray analysis of prostate cancer tissues with an >2-fold change and a p-value <0.01 were considered significant. We identified sets of genes that are involved in the metastatic cascade and are known to be implicated in prostate cancer to show changes in the expression patterns due to the Ets-1 blockade in PC3 cells. Correlating these sets of genes with the findings in prostate cancer tissues, we identified 16 genes that are up- or down-regulated in healthy compared to tumor prostate glands. Further investigation revealed that 4 out of the 16 genes have been reported to be regulated by members of the ETS family. These findings provide in vitro and in vivo evidence for the importance of Ets-1 in the development and progression of prostate cancer.