Abstract 5040: Genomic and proteomic characterization of anti-androgen resistant cell lines
Authors: Hertzog Jennifer , Russell Mike , Quigley Michael , Gottardis Marco , McDevitt. Theresa 
Published: July 2016

Background: Prostate cancer is the most common cancer and second most frequent cause of cancer-related deaths for men in the United States. AR-axis inhibitors have been shown to improve both progression-free survival (PFS) and overall survival (OS) in castration resistant prostate cancer (CRPC) patients however an estimated 50% of patients will go on to develop resistance to these therapies. Some mechanisms of resistance observed in the clinic include Androgen Receptor (AR) dependent events such as increased AR copy number, activating point mutations in AR, or splice variants (ARV7) both of the latter leading to constitutively active versions of AR. Alternatively, AR-independent resistance mechanisms include up-regulation of other oncogenic signaling pathways such as FGFR and PI3/Akt and induction of the nuclear hormone Glucocorticoid Receptor (GR). Finally, an increase in the emergence of a neuroendocrine phenotype is observed in the clinic with CRPC patients and is thought to be associated with chronic AR-antagonist treatment. To better understand the specific proteomic and genomic changes that occur during chronic AR inhibitor treatment we developed two enzalutamide (ENZA) resistant cell lines and performed targeted proteomic and global gene expression analysis.

Methods: We generated LnCaP and VCAP ENZA-resistant (ENZA-Res) prostate cancer cell lines. We performed gene expression analysis by using both cDNA microarray and RNA-SEQ techniques to identify novel or differential gene expression patterns between ENZA-Res and sensitive phenotypes. We also employed a targeted proteomic approach to identify changes in the relative expression levels of proteins that have historically been associated with anti-androgen resistance including, ARV7, GR and SGK-1.

Results: We have shown that ENZA-Res cell lines can undergo a significant change in morphology that is associated with an elongated neuronal-like appearance. This phenotype is associated with an induction in the mRNA expression of neuroendocrine markers, CHGA and REST along with a strong induction of GR mRNA and protein expression. We have shown that the neuroendocrine derived prostate cancer cell line, H660, also demonstrates high GR mRNA and protein content suggesting that GR may have a role in the maintenance of neuroendocrine and/ or ENZA-Res phenotypes when AR is absent. In VCaP ENZA-Res cells a significant increase in ARV7 mRNA and protein content was observed compared to parental ENZA sensitive VCaP cells. Lastly, we employed a combination of cDNA microarray and RNA-SEQ techniques to identify a molecular signature associated with anti-androgen resistance. We have identified a unique subset of genes that are differentially up-regulated in ENZA-Res cell lines compared to ENZA-sensitive cell lines. This novel molecular signature identifies several candidate genes as potential therapeutic targets that may be important in mediating anti-androgen resistance.

Citation Format: Jennifer Hertzog, Mike Russell, Michael Quigley, Marco Gottardis, Theresa McDevitt. Genomic and proteomic characterization of anti-androgen resistant cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5040.