AHR plays important roles in mediating diverse responses to Enzalutamide in prostate cancer

Enzalumatide (ENZ) is a widely used second generation nonsteroidal Androgen Receptor inhibitor that is integral in managing castration-resistant prostate cancer (CRPC). However, resistance inevitably develops in months and limits the clinical benefits of ENZ. AHR is commonly upregulated in ENZ-resistant (ENZR) cell lines and is essential for ENZR CRPC growth in vitro and in vivo. Interestingly, the canonical AHR xenobiotic pathway does not seem to play a role. To characterize, for the first time, transcriptional targets of AHR in prostate cancer, we performed ChIP-seq of AHR and H3K9ac, a marker of active chromatin, in CWR-R1ENZR cells. An AHR knockdown cell line is also included to identify the difference of AHR trancriptional action. ChIP-seq results revealed that AHR binds to multiple genes targeted by AR and glucocorticoid receptor (GR), a well-established mechanism bypassing the AR blockade of ENZ. Furthermore, AHR also binds to many marker genes of neuroendocrine (NE) differentiation, a feature indicating AR-independence and clinical aggressiveness in prostate cancer. Together, these results depict AHR as an important regulator of reponses to ENZ in CRPC. Overall design: ChIP-seq of AHR and H3K9ac in control CWR-R1ENZR cells; ChIP-seq of AHR in AHR knockdown CWR-R1ENZR cells

恩扎卢胺（Enzalumatide, ENZ）是一款广泛应用的第二代非甾体类雄激素受体（Androgen Receptor, AR）抑制剂，在去势抵抗性前列腺癌（castration-resistant prostate cancer, CRPC）的临床管理中具有不可或缺的地位。然而，肿瘤耐药性往往在数月内不可避免地产生，限制了恩扎卢胺的临床获益。芳香烃受体（Aryl Hydrocarbon Receptor, AHR）在恩扎卢胺耐药（ENZ-resistant, ENZR）细胞系中通常呈高表达状态，且对ENZR型CRPC的体外与体内生长均至关重要。值得注意的是，经典的AHR异源生物代谢通路似乎并未参与这一过程。为首次系统表征前列腺癌中AHR的转录靶标，我们在CWR-R1^ENZR细胞中开展了针对AHR与活性染色质标记物H3K9乙酰化（H3K9ac）的染色质免疫沉淀测序（ChIP-seq）实验；同时构建了AHR敲低细胞系，以区分AHR的转录调控作用差异。ChIP-seq结果显示，AHR可结合多个受AR与糖皮质激素受体（glucocorticoid receptor, GR）调控的靶基因——这是一种公认的绕过恩扎卢胺AR阻断作用的耐药机制。此外，AHR还可结合众多神经内分泌（neuroendocrine, NE）分化标记基因，该特征提示前列腺癌已脱离AR依赖且临床侵袭性显著增强。综上，本研究结果表明AHR是CRPC中恩扎卢胺应答反应的重要调控因子。整体实验设计：在对照CWR-R1^ENZR细胞中开展AHR与H3K9ac的ChIP-seq测序；在AHR敲低的CWR-R1^ENZR细胞中开展AHR的ChIP-seq测序。