Small molecules modulating RNA-binding protein Msi1

描述（由申请人提供）：Musashi-1 （Msi1）是在许多类型的癌症中过表达的干细胞标记物。Msi1是一种rna结合蛋白（RBP），结合并抑制靶mrna的翻译。这种抑制导致Wnt和Notch信号的激活，从而导致细胞周期的进展、存活和对程序性细胞死亡的抵抗。降低乳腺癌和结肠癌细胞系中Msi1水平的实验操作导致小鼠异种移植模型中的肿瘤消退。由于Msi1刺激Notch和Wnt信号，并在多种癌症中过表达，因此Msi1是开发新型癌症治疗的一个有吸引力的靶点。到目前为止，还没有报道过Msi1-RNA相互作用的小分子抑制剂。由于缺乏明确定义的靶RNA结合袋，诸如Msi1之类的rbp被认为是“不可药物的”。通过高通量筛选，我们获得了纳米摩尔Ki的初始点，并通过表面等离子体共振（SPR）和核磁共振（NMR）进行了验证。我们的假设是，破坏Msi1- rna结合的小分子化合物会阻断Msi1的功能，导致靶基因的翻译，这对抑制癌细胞的生长和进展至关重要。我们的目标是获得一系列小分子化合物作为化学探针，可以有效结合Msi1并调节其功能，最终选择1-2种最类似药物的先导化合物作为进一步开发的一类全新的分子癌症治疗药物，以抑制Msi1过表达的癌症。为了验证我们的假设，将进行三个具体目标：AIM 1，基于结构的msi1抑制剂的合理设计和先导优化；AIM 2，体外抗肿瘤活性、靶点验证及作用机制研究；目的3:msi1先导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：成功实施，该项目将发现新的Msi1化学探针和潜在的先导化合物作为Msi1抑制剂，抑制具有高水平Msi1- notch /Wnt信号的癌细胞。这些msi1抑制剂的发现将：(1)为描述Msi1-Notch/Wnt信号在癌症发生和发展中的功能作用提供有效和有用的化学探针；(2)为开发靶向肿瘤蛋白Msi1的新型分子疗法提供有前景的先导化合物。获得的数据和线索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。在评估了结构-活性关系和先导化合物优化之后，我们可能会获得一些先导化合物，作为一种全新的分子癌症治疗药物，用于抑制癌细胞生存和发展所需的特定蛋白质/RNA相互作用。

DESCRIPTION (provided by applicant): 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.