Abstract LB-136: Creation of androgen independent prostate cancer cell lines using targeting nucleases.

Abstract

Abstract Understanding mechanisms by which advanced prostate cancer (PCa) progresses to a castration resistant PCa (CRPC) phenotype is crucial for tailoring targeted therapies for individual patients. Constitutively active androgen receptor (AR) splice variants that lack the ligand binding domain drive androgen independent growth in cell lines and xenograft models of PCa and their overexpression in CRPC metastases is associated with poor prognosis. However, the mechanism of AR splice variant overexpression in CRPC is not completely understood. We have shown that diverse genomic rearrangements within the AR gene are linked to AR splicing alterations in PCa cell lines, xenografts, and CRPC metastases. To test whether these AR gene rearrangements drive AR splice variant synthesis and a CRPC phenotype, we developed transcription activator-like effector nucleases (TALENs) for precision genome engineering in androgen-sensitive PCa cells. Engineering of specific AR gene rearrangements induced splicing alterations and efficient expression of AR splice variants. Functionally, these genome-engineered cells displayed constitutive, ligand-independent AR transcriptional activity and an androgen-independent growth profile. These fundamental properties of CRPC were blocked following siRNA-mediated knock-down of truncated AR variants. Overall, these data demonstrate that AR gene rearrangements induce fundamental aspects of the CRPC phenotype including constitutive, ligand-independent, AR splice variant activity. Overall, these data advance the concept of AR splice variants as key drivers of advanced disease, and provide new genome-engineered models that could be used to develop agents targeted to these AR-derived species. Citation Format: Michael D. Nyquist, Yingming Li, Scott M. Dehm. Creation of androgen independent prostate cancer cell lines using targeting nucleases. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-136. doi:10.1158/1538-7445.AM2013-LB-136