CREB5 promotes resistance to androgen-receptor antagonists and androgen deprivation in prostate cancer

Inhibition of androgen-receptor (AR)signaling is the foundation of therapeutic regimens for advanced prostate cancers. However, nearly all patientsdevelop resistance and some never respond. To identify genes that mediate resistance to androgen ablation therapy, we performed an open reading frame (ORF) expression screen of17,255 ORFs and found that the transcription factorCREB5robustly conferred resistance to androgen deprivation and AR inhibition by enzalutamide. CREB5 overexpressionincreased enzalutamide-resistance 45-fold, enhanced resistance of tumor xenografts. CREB5 expression was also essential for enzalutamide-resistance patient-derived organoids. In clinical mCRPC, CREB5is frequently amplified and itsoverexpression positively correlated with castration resistance gene signatures including those of MYC and cell cycle. Mechanistically, CREB5 directly interacted at AR binding sites andenhanced site-specific AR bindingin enzalutamide. This dysregulated expression of 393 AR target genes including MYC and CDK1.These observations identifyCREB5asadriver of enzalutamide-resistance in a subset of advancedprostate cancer. To perform ChIpseq (H3K27Ac, AR, FoxA1 or CREB5 antibody), ATAC seq or RNAseq in LNCaP cells expressing either luciferase or CREB5 after treatment either enzalutamide or DMSO control.

雄激素受体（androgen-receptor, AR）信号通路抑制是晚期前列腺癌治疗方案的核心基础。然而，几乎所有患者都会产生耐药性，部分患者甚至从初始治疗阶段即无应答。为鉴定介导雄激素剥夺治疗耐药的基因，我们对17255个开放阅读框（open reading frame, ORF）开展了全基因组表达筛选，发现转录因子CREB5可显著增强细胞对雄激素剥夺以及恩扎卢胺（enzalutamide）介导的AR抑制的耐药性。CREB5过表达可使细胞对恩扎卢胺的耐药性提升45倍，同时增强肿瘤异种移植模型的耐药能力。CREB5的表达对于恩扎卢胺耐药的患者来源类器官（patient-derived organoids）同样至关重要。在临床转移性去势抵抗性前列腺癌（metastatic castration-resistant prostate cancer, mCRPC）样本中，CREB5常发生基因扩增，且其过表达与MYC、细胞周期等去势抵抗相关基因特征呈正相关。机制层面，CREB5可直接结合AR结合位点，并在恩扎卢胺处理条件下增强位点特异性的AR结合能力，进而失调包括MYC与CDK1在内的393个AR靶基因的表达。上述研究结果确认，CREB5是部分晚期前列腺癌患者恩扎卢胺耐药的驱动因子。后续我们将在分别表达荧光素酶或CREB5的LNCaP细胞中，经恩扎卢胺或二甲基亚砜（dimethyl sulfoxide, DMSO）对照处理后，开展使用H3K27Ac、AR、FoxA1或CREB5抗体的染色质免疫沉淀测序（ChIPseq）、ATAC测序（ATAC seq）以及RNA测序（RNAseq）实验。