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）是胚胎致死性异常视力（ELAV）家族的成员，可与位于靶mRNA的3 '或5'非翻译区（UTR）中的腺嘌呤和尿苷富集元件（ARE）结合。HuR在多种癌症中过表达，通过与涉及肿瘤细胞增殖、存活、血管生成、侵袭和转移的致癌mRNA的子集相互作用促进肿瘤发生。HuR通过与战神结合并促进mRNA的稳定性和翻译，上调致癌Musashi-1/2（Msi 1/2）和抗凋亡蛋白Bcl-2和XIAP，从而导致Wnt/Notch信号通路的激活和细胞凋亡的抑制。这些HuR靶基因也参与癌症干细胞信号传导和耐药性。这些发现表明HuR是开发新型癌症治疗的有吸引力的靶点。 到目前为止，在直接抑制HuR-RNA相互作用的小分子方面的成功有限。RNA结合蛋白被认为是“不可用药的”，因为缺乏明确定义的靶RNA结合口袋。通过高通量筛选，我们获得了抑制HuR的命中率，Ki值为nM至μM，并通过ALPHA、表面等离子体共振（SPR）和核磁共振（NMR）测定进行了验证。我们假设直接破坏HuR-ARE相互作用的小分子或HuR-ARE破坏剂将阻断HuR功能，从而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有效结合HuR并调节其功能的小分子化合物，并最终选择1-2个最具药物样的先导化合物用于进一步开发，作为一类新的抑制HuR过表达的癌症的分子癌症治疗。提出了三个具体目标：AIM 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、靶标验证和作用机制（MOA）研究; AIM 3，在人类癌症异种移植模型（包括原位肿瘤模型）中先导HuR-ARE干扰物的体内疗效研究。 总体影响：该项目的成功实施将发现HuR的新型化学探针和潜在的先导化合物作为HuR-ARE干扰物，抑制具有高水平HuR-Notch/Wnt信号的癌细胞。发现这种HuR-ARE干扰物将：（1）提供有效和特异性的化学探针，用于描述HuR-Msi 1-Notch/Wnt信号传导在癌症发生和进展中的功能作用;和（2）提供有前途的先导化合物，以开发靶向致癌HuR的新型分子治疗剂。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）和先导化合物优化后，我们可能会获得一些先导化合物，用于进一步开发，作为一类全新的分子癌症治疗剂，抑制癌细胞存活和进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.