Targeting Glucose Transporters Using Rapafucins

药物发现中的一个主要挑战是寻找小分子抑制剂 具有挑战性的目标，包括蛋白质-蛋白质相互作用和多通道 跨膜蛋白。大自然进化出了一种巧妙的解决方案来解决这个问题 如大环天然产物的免疫亲和素配体家族所示， 包括雷帕霉素和FK506。除了它们自己的较大尺寸之外， 与蛋白质更广泛的相互作用，这些天然产品也招募了 FKBP-之前形成更大二聚体络合物的伴侣家族 与它们各自的靶点mTOR和钙调神经磷酸酶联系在一起。受此启发 独特的作用模式，我们产生了一个包含45,000种类似雷帕霉素的化合物文库 大环，称为Rapafucins，通过融合雷帕霉素的FKBP结合域 用一个组合的四肽文库。对这个图书馆的筛选导致了 发现溶质载体(SLC)转运体超家族的多个成员， 包括葡萄糖转运蛋白(Glut)家族的成员。两种截然不同的抑制物 分别鉴定为Rapaglutin A(RGA)和Rapaglutin E(RGE)。鉴于RGE 是GLUT1高度特异的，RGA似乎抑制了多种GLUT异构体。RGA 已经被证明在乳腺癌的异种移植模型中是有效的，而RGE 被发现通过阻断DNA-1来抑制细胞内T细胞受体信号传导 NFAT的结合活性。我们将进一步鉴定RGA的抗肿瘤活性 通过系统地评估其对细胞代谢谱的影响和 AMPK-mTOR信号通路。在初步研究中，我们发现RGA 联合用药对三阴性乳腺癌细胞的抑制作用有协同作用 (TNBC)。我们将进一步阐明协同作用的机制和 RGA联合苯福明体内抑制TNBC肿瘤生长的实验研究那就是Rge 抑制钙离子刺激NFAT的DNA结合活性提示其潜在的作用 GLUT1在细胞内T细胞受体信号转导中的作用我们将澄清 RGE免疫抑制作用的机制研究 RGE在体内作为免疫抑制剂的潜力。最后，使用一个新的 开发的微阵列平台，我们将根据每一个 谷氨酸的14种亚型寻找不同亚型的特异性抑制物 它可以成为研究过剩生物学的新的化学工具。

A major challenge in drug discovery is to identify small molecule inhibitors for the challenging targets including protein-protein interactions and multi-pass transmembrane proteins. Nature has evolved an ingenious solution to this problem as exemplified by the immunophilin ligand family of macrocyclic natural products, including rapamycin and FK506. Aside from their own larger sizes that enable more extensive interactions with proteins, these natural products also recruit the FKBP-family of chaperones to form much larger dimeric complexes before associating with their respective targets, mTOR and calcineurin. Inspired by this unique mode of action, we generated a 45,000-compound library of rapamycin-like macrocycles, named rapafucins, by fusing the FKBP-binding domain of rapamycin with a combinatorial tetrapeptide library. Screening of this library has led to the discovery of multiple members of the solute carrier (SLC) transporter superfamily, including members of the glucose transporter (GLUT) family. Two distinct inhibitors of GLUT were identified, rapaglutin A (RgA) and rapaglutin E (RgE). Whereas RgE is highly specific for GLUT1, RgA seems to inhibit multiple GLUT isoforms. RgA has been shown to be efficacious in a xenograft model of breast cancer while RgE was found to inhibit intracellular T cell receptor signaling by blocking the DNA- binding activity of NFAT. We will further characterize the antitumor activity of RgA by systematically assessing its effect on cellular metabolomic profiles and the AMPK-mTOR signaling pathway. In preliminary studies, we have found that RgA and phenformin have synergy in inhibiting triple negative breast cancer cells (TNBC). We will further delineate the mechanism of synergy and the effect of the RgA-phenfomin combination for inhibiting TNBC tumor growth in vivo. That RgE inhibited calcium stimulated DNA-binding activity of NFAT suggests a potential role of GLUT1 in regulating intracellular T cell receptor signaling. We will elucidate the mechanism underlying the immunsuppressive activity of RgE and investigate the potential of RgE as an immunosuppressant in vivo. Lastly, using a newly developed microarray platform, we will screen rapafucin libraries against each of the 14 isoforms of GLUTs in search of specific inhibitors of different isoforms of GLUT, which can become new chemical tools for studying the biology of GLUT.