Activation of the oncogene ERG by the Ras/ERK and PI3K/AKT pathways

Abstract

Background and Hypothesis: The TMPRSS2-ERG re-arrangement occurs in ~50% of prostate cancers and results in aberrant expression of the transcription factor ERG in the prostate. ERG is known to be activated by the Ras/ERK and PI3K/AKT pathways, however, the exact mechanism of this activation is not fully understood. The aim of this project is to identify how activation of these signaling pathways differentially effect transcription of ERG target genes. Experimental Design or Project Methods: In order to test how the Ras/ERK and PI3K/AKT pathways effect ERG target gene transcription, normal prostate epithelial cells (RWPE1) were transfected with constitutively active AKT in combination with phospho-mutants of ERG. These cell lines were then used to conduct Quantitative Reverse Transcription PCR and Western blotting of known downstream ERG target genes to identify how the activation status of these signaling pathways affected transcription and protein production. Results: Overall, our results demonstrate that ERG mediated transcription of the VIM gene, a marker of EMT, was activated by the Ras/ERK pathway and was repressed by the PI3K/AKT pathway. In addition, we found that ERG expression decreased FOXO1 protein expression in our cell lines regardless of Ras/ERK and PI3K/AKT status. Transcription and protein quantification was also measured for ERG target gene VEGFA, a critical regulator of angiogenesis. Conclusion and Potential Impact: This project helps identify the molecular mechanisms by which a common oncogene in prostate cancer is activated. Our results demonstrate how upstream signaling pathways differentially regulate oncogenic transcription and cell transformation. Overall, this project will provide insight to the molecular mechanisms of possible therapeutic targets in prostate cancer, the most common cancer amongst men.