Abstract 2197: Dysregulated alternative splicing landscape identifies intron retention as a hallmark and spliceosome as a therapeutic vulnerability in aggressive prostate cancer

Abstract

Abstract Dysregulation of mRNA alternative splicing (AS) has been implicated in development and progression of hematological malignancies. How the global AS dysregulation contributes to the development and progression of solid tumors is under-studied and remains generally unclear. Here we describe the first comprehensive AS landscape in the spectrum of human prostate cancer (PCa) development, progression and therapy resistance. We find that the severity of splicing dysregulation correlates with disease progression and establish intron retention (IR) as a hallmark of PCa stemness and aggressiveness. Systematic interrogation of 274 splicing-regulatory genes (SRGs) uncovers prevalent SRG mutations associated with, mainly, copy number variations leading to mis-expression of ~68% of SRGs during PCa evolution. Consequently, we identify many SRGs as prognostic markers associated with splicing disruption and patient outcome. Interestingly, androgen receptor (AR) controls a splicing program distinct from its transcriptional regulation. The spliceosome modulator, E7107, reverses cancer aggressiveness and inhibits the growth of castration-resistant PCa (CRPC) xenograft models and of the autochthonous Hi-Myc tumors. Altogether, our studies establish aberrant AS landscape caused by dysregulated SRGs as a hallmark of PCa aggressiveness and a novel therapeutic vulnerability for CRPC. Citation Format: Dingxiao Zhang, qiang Hu, Xiaozhuo Liu, Yibing Ji, Hsueh-Ping Chao, Amanda Tracz, Jason Kirk, Silvia Buonamici, Ping Zhu, Jianmin Wang, song liu, Dean Tang. Dysregulated alternative splicing landscape identifies intron retention as a hallmark and spliceosome as a therapeutic vulnerability in aggressive prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2197.