Small molecules modulating RNA-binding protein Msi1

摘要 武藏-1(Musashi-1，Msi1)是一种干细胞标记物，在许多类型的癌症中过度表达。MSI1是一种RNA结合蛋白 结合并抑制靶mRNAs翻译的蛋白质(RBP)。这种抑制会导致Wnt的激活 和Notch信号，因此，细胞周期进程、存活和对编程细胞的抵抗 死亡。降低乳腺和结肠癌细胞系Msi1水平的实验操作导致肿瘤 小鼠异种移植模型中的退化。因为MSI1同时刺激Notch和Wnt信号，并且是 Msi1在多种癌症中过度表达，是开发新的癌症治疗方法的一个有吸引力的靶点。 到目前为止，还没有关于Msi1-RNA相互作用的小分子抑制剂的报道。Msi1等RBP是 由于缺乏明确的靶向RNA结合口袋，因此被认为是“无法下药的”。直通高 通过通量筛选，我们在纳米分子KI上获得了初步的命中，并通过表面等离子激元进行了验证 磁共振(SPR)和核磁共振(核磁共振)。我们的假设是小分子化合物 破坏Msi1-RNA结合将阻断Msi1的功能，导致关键的靶基因的翻译 抑制癌细胞生长和进展。我们的目标是获得一系列小分子化合物 作为与MSI1有效结合并调节其功能的化学探针，最终选择1-2种大多数药物- 像先导化合物一样，进一步发展成为一种全新的分子癌症治疗方法，抑制 Msi1过表达的癌。 为了验证我们的假设，将实现三个具体目标：目标1、基于结构的合理设计和 Msi1-抑制剂的主导优化；AIM 2，体外抗肿瘤活性，靶点验证，及其作用机制 行动研究；目的3，先导Msi1抑制剂在人类癌症异种移植模型中的体内疗效研究。 总体影响：该项目成功实施，将为MSI1和Msi1发现新的化学探针 潜在的先导化合物作为Msi1抑制物，抑制高水平Msi1-Notch/Wnt的癌细胞 发信号。这种msi1抑制剂的发现将：(1)提供有效和有用的化学探针来描述 Msi1-Notch/Wnt信号在肿瘤发生和发展中的功能作用；以及(2)提供了有希望的 先导化合物开发针对癌蛋白Msi1的新型分子疗法。数据和线索 所取得的成果将使我们能够为进一步的药物发现和开发研究寻找合作伙伴。之后 评估构效关系和先导优化，我们可能会得到一些先导化合物 作为一类全新的抑制特定蛋白质/RNA的分子癌症治疗药物的进一步发展 癌细胞生存和发展所需的相互作用。

SUMMARY Musashi-1 (Msi1) is a stem cell marker overexpressed in many types of cancers. Msi1 is an RNA-binding protein (RBP) that binds to and inhibits translation of target mRNAs. This inhibition results in activation of Wnt and Notch signaling and consequently, cell cycle progression, survival, and resistance to programmed cell death. Experimental manipulation to reduce Msi1 levels in breast and colon cancer cell lines leads to tumor regression in mouse xenograft models. Because Msi1 stimulates both Notch and Wnt signaling and is overexpressed in a wide variety of cancers, Msi1 is an attractive target for developing novel cancer therapy. So far there are no reported small molecule inhibitors of the Msi1-RNA interaction. RBPs such as Msi1 are considered "undruggable" due to the lack of a well-defined binding pocket for target RNA. Through high throughput screening, we have obtained initial hits at nanomolar Ki, which are validated by Surface Plasmon Resonance (SPR) and Nuclear Magnetic Resonance (NMR). Our hypothesize that small molecule compounds that disrupt Msi1-RNA binding will block Msi1 function, leading to translation of target genes that are critical for inhibiting cancer cell growth and progression. Our objective is to obtain a series of small molecule compounds as chemical probes that potently bind to Msi1 and modulate its function, and ultimately select 1-2 most drug- like lead compounds for further development as a whole new class of molecular cancer therapy that inhibit cancer with Msi1 overexpression. To test our hypothesis, three Specific Aims will be carried out: AIM 1, Structure-based rational design and lead optimization of Msi1-inhibitors; AIM 2, In vitro anti-tumor activity, target validation, and mechanism of action studies; AIM 3, In vivo efficacy studies of the lead Msi1-inhibitors in xenograft models of human cancer. Overall Impact: Successfully carried out, this project will discover novel chemical probes for Msi1 and potentially lead compounds as Msi1-inhibitors that inhibit cancer cells with high levels of Msi1-Notch/Wnt signaling. Discovery of such Msi1-inhibitors will: (1) provide potent and useful chemical probes for delineating the functional roles of Msi1-Notch/Wnt signaling in cancer initiation and progression; and (2) provide promising lead compounds to develop novel molecular therapeutics targeting the oncoprotein Msi1. The data and leads obtained will enable us to seek out partners for further drug discovery and development studies. After assessing structure-activity relationships and lead optimization, we may obtain a few lead compounds for further development as a whole new class of molecular cancer therapeutics that inhibit specific protein/RNA interactions required for cancer cell survival and progression.