去势-resistant 前列腺癌通常转移至骨骼，这样的骨转移最终会变得对现有治疗方式有抵抗力，导致患者死亡。在骨骼中富含的 TGF-β 在骨转移发展中起着重要作用。然而，直接针对 TGF-β 或其受体治疗骨转移一直是具有挑战性的。我们之前发现，TGF-β 诱导并依赖于转录因子 KLF5 在 K369 处的乙酰化来调控多种生物过程，包括诱导 EMT、细胞浸润和骨转移。因此，乙酰化的 KLF5（Ac-KLF5）及其下游效应可作为治疗前列腺癌 TGF-β诱导的骨转移的潜在治疗靶点。采用球形侵袭实验来筛选 1987 种 FDA 批准的药物，以抑制侵袭。将荧光素酶和 KLF5K369Q 表达细胞经尾静脉注射到裸鼠体内，模拟骨转移。采用生物发光成像、微型 CT 和组织学分析来监测和评估骨转移。采用 RNA 串联反应、生物信息学和生物化学分析来了解硝唑酰胺（NTZ）调控的基因、信号通路和潜在机制。使用荧光滴定、高效液相色谱和圆二色光谱分析评估 NTZ 与 KLF5 蛋白的结合。在筛选和验证实验中，驱虫剂硝唑酰胺被鉴定为强效侵袭抑制剂。在 KLF5K369Q 诱导的骨转移中，NTZ 在预防和治疗模式下均产生强效的抑制作用。NTZ 还抑制了成骨细胞的分化，这是由 KLF5K369Q 导致的骨转移的细胞过程。NTZ 减弱了 KLF5K369Q 在 127 个基因的上调和 114 个基因的下调中的功能。一些基因的表达变化与前列腺癌患者的整体生存率明显相关。其中一项变化是 MYBL2 的上调，该基因在前列腺癌中功能上促进骨转移。其他分析表明，NTZ 结合到 KLF5 蛋白，KLF5K369Q 结合到 MYBL2 的启动子以激活其转录，而 NTZ 减弱了 KLF5K369Q 对 MYBL2 启动子的结合。NTZ 是前列腺癌和其他癌症 TGF-β/Ac-KLF5 信号轴诱导的骨转移的潜在治疗药物。 © 2023 作者。

Castration-resistant prostate cancer often metastasizes to the bone, and such bone metastases eventually become resistant to available therapies, leading to the death of patients. Enriched in the bone, TGF-β plays a pivotal role in bone metastasis development. However, directly targeting TGF-β or its receptors has been challenging for the treatment of bone metastasis. We previously found that TGF-β induces and then depends on the acetylation of transcription factor KLF5 at K369 to regulate multiple biological processes, including the induction of EMT, cellular invasiveness, and bone metastasis. Acetylated KLF5 (Ac-KLF5) and its downstream effectors are thus potential therapeutic targets for treating TGF-β-induced bone metastasis in prostate cancer.A spheroid invasion assay was applied to prostate cancer cells expressing KLF5K369Q, which mimics Ac-KLF5, to screen 1987 FDA-approved drugs for invasion suppression. Luciferase- and KLF5K369Q-expressing cells were injected into nude mice via the tail artery to model bone metastasis. Bioluminescence imaging, micro-CT), and histological analyses were applied to monitor and evaluate bone metastases. RNA-sequencing, bioinformatic, and biochemical analyses were used to understand nitazoxanide (NTZ)-regulated genes, signaling pathways, and the underlying mechanisms. The binding of NTZ to KLF5 proteins was evaluated using fluorescence titration, high-performance liquid chromatography (HPLC), and circular dichroism (CD) analysis.NTZ, an anthelmintic agent, was identified as a potent invasion inhibitor in the screening and validation assays. In KLF5K369Q-induced bone metastasis, NTZ exerted a potent inhibitory effect in preventive and therapeutic modes. NTZ also inhibited osteoclast differentiation, a cellular process responsible for bone metastasis induced by KLF5K369Q. NTZ attenuated the function of KLF5K369Q in 127 genes' upregulation and 114 genes' downregulation. Some genes' expression changes were significantly associated with worse overall survival in patients with prostate cancer. One such change was the upregulation of MYBL2, which functionally promotes bone metastasis in prostate cancer. Additional analyses demonstrated that NTZ bound to the KLF5 protein, KLF5K369Q bound to the promoter of MYBL2 to activate its transcription, and NTZ attenuated the binding of KLF5K369Q to the MYBL2 promoter.NTZ is a potential therapeutic agent for bone metastasis induced by the TGF-β/Ac-KLF5 signaling axis in prostate cancer and likely other cancers.© 2023. The Author(s).