The Development of Stat3 Inhibitors

描述（由申请人提供）：信号转导和转录激活因子3（Stat 3）是STAT转录因子家族的成员，其将来自质膜上的细胞外信号传导蛋白受体的信号直接与细胞核相关。Stat 3与来自IL-6家族成员和生长因子如EGF和PDGF的信号相关。Stat 3在几种癌症类型中被组成性激活，例如乳腺癌、前列腺癌、卵巢癌、白血病、多发性骨髓瘤等。将反义和显性负性基因构建体引入肿瘤细胞系中导致生长停滞和凋亡。因此，Stat 3是抗癌药物设计的靶点。我们的总体假设是靶向SH 2结构域的小分子Stat 3抑制剂将是用于治疗癌症的有效化疗剂。在本基金的第一次提交中，我们发现了一个高亲和力的磷酸肽模板Ac-pTyr-Leu-Pro-Gln-Thr-Val-NH 2，并由此开发了一种拟肽抑制剂。我们表明，稳定的磷酸肽序列和拟肽产物能够在细胞测定中抑制Stat 3活性，并且我们证明了培养物中乳腺肿瘤和多发性骨髓瘤细胞的生长停滞，尽管是在高浓度（10-25 μ M）下。在该提案中，我们的目标是增加我们的抑制剂对Stat 3的亲和力，使其成为更有效的化疗剂。我们的具体目标是（1）合成我们的抑制剂的靶向文库，其掺入构象受限的构建块以获得关于与Stat 3结合的我们的化合物的构象的信息并增加亲和力，（2）使用X射线晶体学确定与Stat 3结合的我们的抑制剂的结构，用于结构指导的抑制剂设计（3）在培养物中测定我们的化合物作为Stat 3活性和肿瘤细胞生长的抑制剂（4）在小鼠肿瘤模型中测试我们的化合物作为抗癌剂。

DESCRIPTION (provided by applicant): Signal transducer and activators of transcription 3 (Stat3) is a member of the STAT family of transcription factors that relate signals from extracellular signaling protein receptors on the plasma membrane directly to the nucleus. Stat3 relates signals from IL-6 family members and growth factors such as EGF and PDGF. Stat3 is constitutively activated in several cancer types, such as breast, prostate, ovarian, leukemia, multiple myeloma, etc. Introduction of antisense and dominant negative gene constructs into tumor cells lines results in growth arrest and apoptosis. Thus Stat3 is a target for anticancer drug design. Our overall hypothesis is that small molecule Stat3 inhibitors targeted to the SH2 domain will be effective chemotherapeutic agents for the treatment of cancer. In the first submission of this grant we found a high affinity phospho-peptide template, Ac-pTyr-Leu-Pro-Gln-Thr-Val-NH2, and from this developed a peptidomimetic inhibitor. We showed that stabilized phosphopeptide sequences and peptidomimetic prod rugs were able to inhibit Stat3 activity in cellular assays and we demonstrated growth arrest of breast tumor and multiple myeloma cells in culture, although at high concentrations (10-25 microM). In this proposal we aim to increase the affinity of our inhibitors for Stat3 to make them more potent chemotherapeutic agents. Our specific aims are (1) Synthesize targeted libraries of our inhibitor incorporating conformationally constrained building blocks to gain information on the conformation of our compounds bound to Stat3 and to increase affinity, (2) Determine the structure of our inhibitors bound to Stat3 using X-ray crystallography for use in structure- guided inhibitor design (3) Assay our compounds as inhibitors of Stat3 activity and tumor cell growth in culture (4) Test our compounds as anti-cancer agents in tumor models in mice.