Molecular cancer therapy targeting HuR-ARE interaction

 描述(由申请人提供)：RNA结合蛋白Hu抗原R(Hur)是胚胎致死性视觉异常(ELAV)家族的成员，它与位于靶mRNA3‘-或5’-非翻译区(UTR)的富含腺嘌呤和尿苷的元件(ARE)结合。HUR在多种癌症中过表达，通过与肿瘤细胞增殖、存活、血管生成、侵袭和转移相关的致癌基因亚群相互作用而促进肿瘤的发生。HUR通过与Ares结合，上调致癌蛋白Musashi-1/-2(Msi1/2)和抗凋亡蛋白Bcl2和XIAP，促进mRNA的稳定和翻译，从而激活Wnt/Notch信号通路，抑制细胞凋亡。这些HUR靶基因还与癌症干细胞信号和耐药性有关。这些发现表明，HUR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，在直接抑制Hur-RNA相互作用的小分子方面取得的成功有限。由于缺乏明确的靶向RNA结合口袋，RNA结合蛋白被认为是“不能下药的”。通过高通量筛选，我们获得了在NM到微米KI值时抑制HUR的HITS，并通过阿尔法、表面等离子体共振(SPR)和核磁共振(核磁共振)分析进行了验证。我们假设，直接破坏Hur-Are相互作用的小分子，或Hur-是干扰物，将阻止Hur功能，导致对癌细胞生长和进展至关重要的靶基因的调节。我们的目标是获得一系列与Hur有效结合并调节其功能的小分子化合物，最终选择1-2个最具药物样先导化合物作为一类新的分子癌症治疗药物，抑制Hur过表达的癌症。提出了三个具体的目标：目的1，基于结构的合理设计和Hur-Are干扰物的先导优化；AIM 2，体外抗肿瘤活性、靶点验证和作用机制(MOA)研究；AIM 3，Hur-Are干扰物在包括原位肿瘤模型在内的异种移植瘤模型中的体内有效性研究。总体影响：该项目成功实施后，将发现针对Hur的新型化学探针和潜在的先导化合物，因为Hur-是通过高水平的Hur-Notch/Wnt信号抑制癌细胞的干扰物。这种Hur-Are干扰物的发现将：(1)提供有效和特异的化学探针来描述Hur-Msi1-Notch/Wnt信号在癌症发生和发展中的功能作用；(2)提供有前景的先导化合物，以开发针对致癌Hur的新型分子治疗药物。所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。在评估结构-活性关系(SAR)和先导优化后，我们可能会获得一些先导化合物，用于进一步开发一类全新的分子癌症治疗药物，这些药物可以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): The RNA-binding protein Hu antigen R (HuR) is a member of the embryonic lethal abnormal vision (ELAV) family that binds to adenine- and uridine-rich elements (ARE) located in the 3'- or 5'-untranslated region (UTR) of target mRNAs. HuR is overexpressed in a wide variety of cancer, promotes tumorigenesis by interacting with a subset of oncogenic mRNAs implicated in tumor cell proliferation, survival, angiogenesis, invasion, and metastasis. HuR up-regulates the oncogenic Musashi-1/-2 (Msi1/2) and anti-apoptotic proteins, Bcl-2 and XIAP, via binding to AREs and promoting mRNA stability and translation, thus leading to activation of Wnt/Notch signaling pathways and inhibition of apoptosis. These HuR target genes are also involved in cancer stem cell signaling and drug resistance. These findings suggest that HuR is an attractive target for developing novel cancer therapy. So far there is limited success in small molecules that directly inhibit the HuR-RNA interaction. RNA-binding proteins are considered "undruggable" due to the lack of a well-defined binding pocket for target RNA. Through high throughput screening, we have obtained hits that inhibit HuR at nM to µM Ki values, validated by ALPHA, Surface Plasmon Resonance (SPR) and Nuclear Magnetic Resonance (NMR) assays. We hypothesize that small molecules that directly disrupt the HuR-ARE interaction, or HuR-ARE disruptors, will block HuR function, leading to modulation of target genes that are critical for cancer cell growth and progression. Our objective is to obtain a series of small molecule compounds that potently bind to HuR and modulate its functions, and ultimately select 1-2 most drug-like lead compounds for further development as a new class of molecular cancer therapy that inhibit cancer with HuR overexpression. Three Specific Aims are proposed: AIM 1, Structure-based rational design and lead optimization of HuR-ARE disruptors; AIM 2, In vitro anti-tumor activity, target validation, and mechanism of action (MOA) studies; AIM 3, In vivo efficacy studies of the lead HuR-ARE disruptors in xenograft models of human cancer, including orthotopic tumor models. Overall Impact: Successfully carried out, this project will discover novel chemical probes for HuR and potentially lead compounds as HuR-ARE disruptors that inhibit cancer cells with high levels of HuR-Notch/Wnt signaling. Discovery of such HuR-ARE disruptors will: (1) provide potent and specific chemical probes for delineating the functional roles of HuR-Msi1-Notch/Wnt signaling in cancer initiation and progression; and (2) provide promising lead compounds to develop novel molecular therapeutics targeting the oncogenic HuR. The data and leads obtained will enable us to seek out partners for further drug discovery and development studies. After assessing structure-activity relationships (SAR) 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.