Prostate cancer (PC) is the leading cause of cancer-related mortality in men worldwide. Results from our laboratory have revealed that high expression of E6-Associated Protein (E6AP), together with low promyelocytic leukemia (PML) protein levels, is a predictor of poor PC prognosis. Moreover, studies from our lab and others have demonstrated that E6AP plays a key role in the growth and survival of PC cells. However, the mechanism by which E6AP impacts PC progression remains largely unknown. The aim of this project is, therefore, to discover how E6AP promotes PC progression.
E6AP is an E3 ligase and a transcriptional cofactor. Therefore, we have measured changes in protein and gene expression in response to E6AP knockdown. Changes in the global proteome were measured by mass spectrometry and at the transcriptome level by RNA-Seq. For this purpose, we have used an inducible knockdown expression system in the PC cell line DU145.
Differentially expressed proteins and genes were short-listed based on significance (p-value <5%) and a minimum 1.5 fold-change. The resulting genes/ protein list was then divided into three categories: those that were significantly different only at RNA, those only at protein and those that displayed significant differential expression at both RNA and protein. Bioinformatics analysis of E6AP regulated proteins with known targets and interactors of E6AP is currently underway to triage candidates for future validation.
The protein targets derived from this study are anticipated to reveal the mechanism by which E6AP contributes to PC and enhance our understanding on the role of E6AP in cellular stress.