Purpose: Androgen receptor (AR) antagonism is exacerbated by HOXB13 in castration-resistant prostate cancers (CRPC). However, it is unclear when and how HOXB13 primes CRPCs for AR antagonism. By mass-spectrometry analysis of CRPC extract, we uncovered a novel lysine 13 (K13) acetylation in HOXB13 mediated by CBP/p300. To determine whether acetylated K13-HOXB13 is a clinical biomarker of CRPC development, we characterized its role in prostate cancer biology. Experimental Design: We identified tumor-specific acK13-HOXB13 signal enriched super enhancer (SE)-regulated targets. We analyzed the effect of loss of HOXB13K13-acetylation on chromatin binding, SE proximal target gene expression, self-renewal, enzalutamide sensitivity, and CRPC tumor growth by employing isogenic parental and HOXB13K13A mutants. Finally, using primary human prostate organoids, we evaluated whether inhibiting an acK13-HOXB13 target, ACK1, with a selective inhibitor (R)-9b is superior to AR antagonists in inhibiting CRPC growth. Results: acK13-HOXB13 promotes increased expression of lineage (AR, HOXB13), prostate cancer diagnostic (FOLH1), CRPC-promoting (ACK1), and angiogenesis (VEGFA, Angiopoietins) genes early in prostate cancer development by establishing tumor-specific SEs. acK13-HOXB13 recruitment to key SE-regulated targets is insensitive to enzalutamide. ACK1 expression is significantly reduced in the loss of function HOXB13K13A mutant CRPCs. Consequently, HOXB13K13A mutants display reduced self-renewal, increased sensitivity to enzalutamide, and impaired xenograft tumor growth. Primary human prostate tumor organoids expressing HOXB13 are significantly resistant to AR antagonists but sensitive to (R)-9b. Conclusions: In summary, acetylated HOXB13 is a biomarker of clinically significant prostate cancer. Importantly, PSMA-targeting agents and (R)-9b could be new therapeutic modalities to target HOXB13–ACK1 axis regulated prostate cancers.

中文翻译：

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乙酰化 HOXB13 调节的超级增强子基因定义了去势抵抗性前列腺癌的治疗脆弱性

目的：HOXB13 在去势抵抗性前列腺癌 (CRPC) 中加剧雄激素受体 (AR) 拮抗作用。然而，目前尚不清楚 HOXB13 何时以及如何启动 CRPC 来对抗 AR。通过对 CRPC 提取物进行质谱分析，我们发现了 HOXB13 中由 CBP/p300 介导的新型赖氨酸 13 (K13) 乙酰化。为了确定乙酰化 K13-HOXB13 是否是 CRPC 发展的临床生物标志物，我们表征了它在前列腺癌生物学中的作用。实验设计：我们确定了肿瘤特异性 acK13-HOXB13 信号富集的超级增强子 (SE) 调节靶点。我们通过使用同基因亲本和 HOXB13K13A 突变体分析了 HOXB13K13 乙酰化缺失对染色质结合、SE 近端靶基因表达、自我更新、恩杂鲁胺敏感性和 CRPC 肿瘤生长的影响。最后，使用原代人类前列腺类器官，我们评估了用选择性抑制剂 (R)-9b 抑制 acK13-HOXB13 靶标 ACK1 在抑制 CRPC 生长方面是否优于 AR 拮抗剂。结果：acK13-HOXB13 通过建立肿瘤特异性 SE，在前列腺癌发展早期促进谱系（AR、HOXB13）、前列腺癌诊断（FOLH1）、CRPC 促进（ACK1）和血管生成（VEGFA、血管生成素）基因表达增加。acK13-HOXB13 招募至关键 SE 调节靶点对恩杂鲁胺不敏感。HOXB13K13A 突变型 CRPC 功能丧失时，ACK1 表达显着降低。因此，HOXB13K13A 突变体表现出自我更新减少、对恩杂鲁胺敏感性增加以及异种移植肿瘤生长受损。表达 HOXB13 的原代人前列腺肿瘤类器官对 AR 拮抗剂显着耐药，但对 (R)-9b 敏感。结论：总之，乙酰化 HOXB13 是具有临床意义的前列腺癌的生物标志物。重要的是，PSMA 靶向药物和 (R)-9b 可能成为靶向 HOXB13-ACK1 轴调节的前列腺癌的新治疗方式。