A systemic medicinal chemistry campaign was conducted based on a literature hit compound 5 bearing the 4,5-dihydro-2H-benzo[b][1,5]oxazocin-6(3H)-one core through cyclization of two side substituents of the bicyclic skeleton combined with N-atom walking or ring walking and the central ring expansion or extraction approaches, leading to several series of structurally unique tricyclic compounds. Among these, compound 29a was identified as the most potent against the Hedgehog (Hh) signaling pathway showing an IC₅₀ value of 23 nM. Mechanism studies indicated that compound 29a inhibited the Hh signaling pathway by suppressing the expression of the transcriptional factors Gli rather than by interrupting the binding of Gli with DNA. We further observed that 29a was equally potent against both Smo wild type and the two major resistant mutants (Smo D473H and Smo W535L). It potently inhibited the proliferation of medulloblastoma cells and showed significant tumor growth inhibition in the ptch± ;p53–/– medulloblastoma allograft mice model. Though more studies are needed to clarify the precise interaction pattern of 29a with Gli, its promising in vitro and in vivo properties encourage further profiling as a new-generation Hh signaling inhibitor to treat tumors primarily or secondarily resistant to current Smo inhibitors.

中文翻译：

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通过抑制Gli介导的转录起作用的新型大环刺猬通路抑制剂的发现。

通过载有两个侧基取代基的4,5-二氢-2 H-苯并[ b ] [1,5]恶唑啉-6（3 H）-一个核心的热门文献5进行了系统的药物化学研究结合N原子行走或环行走以及中心环扩展或提取方法的双环骨架结构，产生了一系列结构上独特的三环化合物。在这些化合物中，化合物29a被确定为对Hedgehog（Hh）信号通路最有效的化合物，IC ₅₀值为23 nM。机制研究表明，化合物29a通过抑制转录因子Gli的表达而不是通过中断Gli与DNA的结合来抑制Hh信号通路。我们进一步观察到29a对Smo野生型和两个主要抗性突变体（Smo D473H和Smo W535L）均具有同等效力。在ptch±; p53 – / –髓母细胞瘤同种异体移植小鼠模型中，它有效抑制了髓母细胞瘤细胞的增殖并显示出显着的肿瘤生长抑制作用。尽管需要更多的研究来阐明29a与Gli的精确相互作用模式，但其有希望的体外和体内特性鼓励其作为新一代Hh信号抑制剂来进一步谱图，以治疗对当前Smo抑制剂有主要或次要抗性的肿瘤。