The transforming growth factor β1 (TGFβ1)/SMAD signaling pathway regulates many vital physiological processes. The development of potent inhibitors targeting activin receptor-like kinase 5 (ALK5) would provide potential treatment reagents for various diseases. A significant number of ALK5 inhibitors have been discovered, and they are currently undergoing clinical evaluation at various stages. However, the clinical demands were far from being met. In this study, we utilized an alternative conformation-similarity-based virtual screening (CSVS) combined with a fragment-based drug designing (FBDD) strategy to efficiently discover a potent and active hit with a novel chemical scaffold. After structural optimization in the principle of group replacement, compound was identified as the most promising ALK5 inhibitor. Compound demonstrated significant inhibitory effects against the TGF-β1/SMAD signaling pathway. It could markedly attenuate the production of extracellular matrix (ECM) and deposition of collagen. Also, the lead compound showed adequate pharmacokinetic (PK) properties and good tolerance. Moreover, treatment with compound in two different xerograph models showed significant inhibitory effects on the growth of pancreatic cancer cells. These results suggested that lead compound refers as a promising ALK5 inhibitor both and , which merits further validation.

中文翻译：

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吡唑并[3,4-d]嘧啶衍生物的设计、合成和评估作为新型有效的TGFβ1R1抑制剂

转化生长因子 β1 (TGFβ1)/SMAD 信号通路调节许多重要的生理过程。针对激活素受体样激酶 5 (ALK5) 的有效抑制剂的开发将为各种疾病提供潜在的治疗试剂。大量 ALK5 抑制剂已被发现，目前正在进行不同阶段的临床评估。但远远不能满足临床需求。在这项研究中，我们利用另一种基于构象相似性的虚拟筛选（CSVS）与基于片段的药物设计（FBDD）策略相结合，有效地发现了新型化学支架的有效和活性命中。经过基团置换原理的结构优化后，化合物被确定为最有前途的ALK5抑制剂。化合物对 TGF-β1/SMAD 信号通路具有显着的抑制作用。它可以显着减弱细胞外基质（ECM）的产生和胶原蛋白的沉积。此外，先导化合物表现出足够的药代动力学（PK）特性和良好的耐受性。此外，在两种不同的静电复印模型中用化合物进行治疗显示出对胰腺癌细胞生长的显着抑制作用。这些结果表明先导化合物是一种有前景的 ALK5 抑制剂，值得进一步验证。