Epithelial-mesenchymal transition (EMT) endows stem cell-like properties to cancer cells. Targeting this process represents a potential therapeutic approach to overcome cancer metastasis and chemotherapy resistance. FiVe1 was identified from an EMT-based synthetic lethality screen and was found to inhibit the stem cell-like properties and proliferation of not only cancer cells undergoing EMT, but also more broadly in mesenchymal cancers that include therapeutically intractable soft tissue sarcomas. FiVe1 functions by directly binding to the type III intermediate filament protein vimentin (VIM) in a mode that induces hyperphosphorylation of Ser56, which results in selective disruption of mitosis and induced multinucleation in transformed VIM-expressing mesenchymal cancer cell types. Cell-based potency (IC₅₀ = 1.6 μM, HT-1080 fibrosarcoma), poor solubility (<1 μM) and low oral bioavailability limits the direct application of FiVe1 as an in vivo probe or therapeutic agent. To overcome these drawbacks, we performed structure-activity relationship (SAR) studies and synthesized a set of 35 new compounds, consisting of diverse modifications of the FiVe1 scaffold. Among these compounds, 4e showed a marked improvement in potency (IC₅₀ = 44 nM, 35-fold improvement, HT-1080) and cell type selectivity (19-fold improvement), when compared to FiVe1. Improvements in the potency of 4e, in terms of overall cytotoxicity, directly correlate with VIM Ser56 phosphorylation status and the oral bioavailability and pharmacokinetic profiles of 4e in mouse are superior to FiVe1. Successful optimization also resulted in potent and selective derivatives 11a, 11j and 11k, which exhibited superior pharmacological profiles, in terms of metabolic stability and aqueous solubility. Collectively, these optimization efforts have resulted in the development of promising FiVe1 analogs with potential applications in the treatment of mesenchymal cancers, as well as in the study of VIM-related biology.

上皮间质转化（EMT）赋予癌细胞类似干细胞的特性。针对这一过程代表了克服癌症转移和化疗耐药性的潜在治疗方法。FiVe1是从基于EMT的合成致死性筛选中鉴定出来的，发现它不仅能抑制经历EMT的癌细胞的干细胞样特性和增殖，而且还能更广泛地抑制间充质癌症，包括难治性软组织肉瘤。FiVe1 的功能是通过直接与 III 型中间丝蛋白波形蛋白 (VIM) 结合，以诱导 Ser56 过度磷酸化的模式，从而选择性破坏有丝分裂，并在表达 VIM 的转化间充质癌细胞类型中诱导多核。基于细胞的效力（IC _{50 = 1.6 μM，HT-1080 纤维肉瘤）、溶解度差（<1 μM）和低口服生物利用度限制了 FiVe1 作为}体内探针或治疗剂 的直接应用。为了克服这些缺点，我们进行了构效关系 (SAR) 研究并合成了一组 35 种新化合物，其中包括 FiVe1 支架的不同修饰。在这些化合物中， 与 FiVe1 相比，4e在效力（IC ₅₀ = 44 nM，35 倍改进，HT-1080）和细胞类型选择性（19 倍改进）方面显示出显着提高。就整体细胞毒性而言，4e效力的改善与 VIM Ser56 磷酸化状态直接相关，并且4e在小鼠中的口服生物利用度和药代动力学特征优于 FiVe1。成功的优化还产生了有效的选择性衍生物11a、11j和11k，它们在代谢稳定性和水溶性方面表现出优异的药理学特征。总的来说，这些优化工作已经开发出有前途的 FiVe1 类似物，在间充质癌症的治疗以及 VIM 相关生物学的研究中具有潜在的应用前景。