Targeting Wnt signaling pathway

蛋白质-蛋白质相互作用（PPI）成为生物有机和药物化学日益重要的目标， 鉴于无数蛋白质复合物在重要生物过程中的关键作用，包括信号转导、细胞 生长和增殖等。由于增强的稳定性和功能多样性，螺旋肽模拟物已 成为一种有前途的针对 PPI 的策略，但其应用仍然像通常那样受到限制 由于三维螺旋结构的差异，它们不能很好地模仿α螺旋。例如， 参与Wnt信号通路的BCL9/β-catenin和TCF/β-catenin PPI在胚胎发育中发挥重要作用 发育和组织稳态，并与多种癌症有关。因此，分子破坏 BCL9/β-catenin 或 TCF/β-catenin PPI 都可以通过抑制 Wnt/β-catenin 成为新型抗癌药物 发信号。然而，成功设计基于非天然支架的螺旋抑制剂来阻断 PPI 仍是一个难题。 以前未知。 我们最近开发了一系列前所未有的螺旋磺基-γ-AA肽，可以模拟α-螺旋 蛋白质的结构域。鉴于 β−catenin/BCL9 和 TCF/β-catenin PPI 的重要性，我们认为 mod- 制定这些 PPI 可以作为制定针对任何目标的总体战略的绝佳机会。 其他涉及 α 螺旋的 PPI。与不表现出细胞活性的 BCL9 和 TCF 肽相比，我们的 初步研究表明磺基-γ-A肽不仅可以模拟这些螺旋结构域，而且还可以 具有高度细胞渗透性，可以通过高度活跃的 Wnt/β-catenin 信号选择性抑制癌细胞的生长。 据我们所知，我们的发现代表了基于非自然的螺旋肽模拟物的第一个例子 破坏这些 PPI 的骨干力量。因此，我们的长期目标是开发新型螺旋磺基-γ-A肽 作为蛋白水解稳定且细胞穿透的分子实体，能够调节多种 医学相关的 PPI。这里的目标是建立磺基-γ-A肽的设计策略： 螺旋结构域模拟物以最佳效力破坏 β−catenin/BCL9 和 TCF/β-catenin PPI。我们首先会 鉴定出螺旋磺基-γ-A肽，可在体外有效破坏 β-catenin/BCL9 和 TCF/β-catenin PPI。福尔- 由此，我们将确认先导化合物的分子机制是通过调节 Wnt 信号传导，通过 使用共焦光谱、TOPFlash 和 FOPFlash 测定、细胞参与测定和相关信号传导 评估这些序列在细胞水平上的选择性、特异性和效力的测定。最后，我们将 使用小鼠肿瘤模型来验证抑制剂在体内抑制 Wnt 信号传导和肿瘤生长的能力。 拟议的工作意义重大，因为这些研究极有可能带来新一代的治疗方法 同时针对 β-catenin/BCL9 PPI 和 β-catenin/TCF PPI 的药物，这将确保抑制 Wnt 的目标 发信号。所提出的工作是创新的，因为我们使用螺旋来模拟蛋白质结构域的策略 磺基-γ-AA肽是全新的，未来可用于靶向多种疾病相关的 PPI。

Protein-protein interactions (PPIs) are increasingly important targets for bioorganic and medicinal chemistry, given the critical role of myriad protein complexes in vital biological processes including signal transduction, cell growth and proliferation, etc. Due to enhanced stability and functional diversity, helical peptidomimetics have emerged as a promising strategy for targeting PPIs, however their application is still limited as they generally do not mimic α-helices well owing to their difference in the three-dimensional helical structures. For instance, BCL9/β-catenin and TCF/β-catenin PPIs involved in Wnt signaling pathway play an important role in embryonic development and tissue homeostasis and are linked to several types of cancers. As such, molecules disrupting either BCL9/β-catenin or TCF/β-catenin PPIs could become novel anti-cancer agents by inhibiting Wnt/β-catenin signaling. However, the successful design of helical inhibitors based on unnatural scaffold to block the PPIs is previously unknown. We have recently developed a series of unprecedented helical sulfono-γ-AApeptides that can mimic α-helical domain of proteins. Given by the significance of β−catenin/BCL9 and TCF/β-catenin PPIs, we believe that mod- ulating these PPIs could serve as an excellent opportunity to formulate the general strategy for targeting any other PPIs involving α-helices. Compared to the BCL9 and TCF peptides not exhibiting cellular activity, our preliminary studies indicated that sulfono-γ-AApeptides not only can mimic these helical domains, but also are highly cell permeable and can selectively inhibit growth of cancer cells with hyperactive Wnt/β−catenin signaling. To the best of knowledge, our findings represents the first example of helical peptidomimetics based on unnatural backbone in disrupting these PPIs. As such, our long-term goal is to develop novel helical sulfono-γ-AApeptides that serve as proteolytically stable and cell-penetrating molecular entities capable of modulating a myriad of medicinally relevant PPIs. The objective here, is to establish the design strategy of sulfono-γ-AApeptides as helical domain mimetics to disrupt β−catenin/ BCL9 and TCF/β-catenin PPIs with optimal potency. We will first identify helical sulfono-γ-AApeptides that potently disrupt β−catenin/BCL9 and TCF/β-catenin PPIs in vitro. Fol- lowing that, we will confirm molecular mechanism of lead compounds is through modulation of Wnt signaling, by using confocal spectroscopy, TOPFlash and FOPFlash assay, cellular engagement assay, and related signaling assays to assess the selectivity, specificity and potency of these sequences on the cellular level. Finally, we will use a mouse tumor model to validate the ability of the inhibitors to inhibit Wnt signaling and tumor growth in vivo. The proposed work is significant, as these studies are highly likely to lead to a new generation of therapeutic agents targeting both β−catenin/BCL9 PPI and β-catenin/TCF PPIs, which will secure the goal of inhibiting Wnt signaling. The proposed work is innovative, because our strategy of protein-domain-mimicking using helical sulfono-γ-AApeptides is completely new and can be adopted to target myriad disease-related PPIs in the future.