A Role For The Ewing'S Sarcoma Breakpoint Protein Ews In Erg-Induced Prostate Tumorigenesis

Abstract The TMPRSS2-ERG gene fusion occurs in one-half of prostate tumors and results in expression of ERG, an ETS family transcription factor that promotes prostate tumorigenesis. Another 5-10% of prostate tumors have similar rearrangements that result in over-expression of other ETS family members such as ETV1, ETV4, and ETV5. However, not all ETS family members are oncogenic, and normal prostate cells express at least 15 of these other ETS factors. Therefore, it is important to understand mechanisms that differentiate oncogenic ETS factors from non-oncogenic ETS factors. We have recently discovered that ERG, ETV1, ETV4, and ETV5, and no other ETS factor can directly bind the protein EWS. This is striking, as EWS is fused to various ETS factors in the chromosomal rearrangements that cause Ewing’s sarcoma. We demonstrate that fusion of EWS to any ETS protein is sufficient for that protein to function like ERG in prostate cells. Furthermore, the EWS-ERG interaction is required for ERG to activate an oncogenic gene expression program and for ERG-mediated tumorigenesis. Therefore, these findings reveal a conserved oncogenic mechanism for prostate cancer and Ewing’s sarcoma. In prostate cancer, aberrant over-expression of an ETS factor that naturally interacts with EWS, brings EWS to ETS-bound regions. In Ewing’s sarcoma this interaction is forced by the presence of an EWS/ETS fusion protein. Therefore, this model predicts that treatments that target EWS function would be effective in both types of cancer. Citation Format: Vivekananda Kedage, Nagarathinam Selvaraj, Taylor R. Nicholas, Justin A. Budka, Travis J. Jerde, Peter C. Hollenhorst. A role for the Ewing’s sarcoma breakpoint protein EWS in ERG-induced prostate tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3510. doi:10.1158/1538-7445.AM2017-3510