The Development of Stat3 Inhibitors

描述(申请人提供)：信号转导和转录激活因子3(STAT3)是STAT转录因子家族的成员，它将质膜上的细胞外信号蛋白受体的信号直接连接到细胞核。STAT3与IL-6家族成员的信号和生长因子如EGF和PDGF有关。STAT3在乳腺癌、前列腺癌、卵巢癌、白血病、多发性骨髓瘤等多种癌症中被结构性激活。将反义和显性负性基因结构导入肿瘤细胞系导致生长停滞和细胞凋亡。因此，STAT3是抗癌药物设计的靶点。我们的总体假设是，针对SH2结构域的小分子STAT3抑制剂将成为治疗癌症的有效化疗药物。在这项资助的第一次提交中，我们发现了一个高亲和力的磷酸多肽模板，Ac-pTyr-Leu-Pro-Gln-Thr-Val-NH2，并由此开发出一种模拟肽的抑制剂。我们发现稳定的磷酸肽序列和模拟多肽的产物在细胞检测中能够抑制STAT3的活性，我们在培养中证明了乳腺肿瘤和多发性骨髓瘤细胞的生长停滞，尽管在高浓度(10-25微米)。在这项建议中，我们的目标是增加我们的抑制剂对STAT3的亲和力，使它们成为更有效的化疗药物。我们的具体目标是(1)合成含有构象受限构建块的靶向抑制剂文库，以获得有关我们的化合物与STAT3结合的构象信息，并提高亲和力；(2)利用X射线结晶学确定我们与STAT3结合的抑制剂的结构，用于结构导向性抑制剂设计；(3)在培养条件下测试我们的化合物作为STAT3活性和肿瘤细胞生长抑制剂的作用；(4)在小鼠肿瘤模型中测试我们的化合物作为抗癌剂的作用。

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.