信号传导与转录活化因子3（STAT3）在乳腺癌细胞中持续异常活化，信号传递过程中STAT3的Coiled-coil（CCD）结构域参与并调控STAT3的活化。因此我们旨在发现一类新型的针对CCD结构域的小分子抑制STAT3的活性达到抗肿瘤的效果。前期我们通过结构依赖的虚拟筛选和荧光偏振的方法进行了筛选，在体外分子水平，通过SPR技术检测小分子与CCD的亲和力是3.20 μM；细胞水平，我们发现小分子能够选择性的抑制含有持续异常活化STAT3的肿瘤细胞系的生长，在此基础上我们对小分子初步进行了优化改造，并探讨了构-效关系，为下一步优化提供依据，我们希望通过点突变方法明确小分子的结合位点，并在细胞和动物水平观测小分子对STAT3信号通路的抑制效果。通过上述实验我们希望开发针对STAT3 CCD的新型小分子抑制剂，优化其成为潜在的针对含有持续活化STAT3的人类肿瘤的抗肿瘤抑制剂。

Signal transducer and activator of transcription 3(STAT3) signaling pathway is constitutively activated in human cancer cells. It is now established that the specificity in signaling are mediated by STAT3 Coiled-coil domain (CCD), which regulate and mediate the interaction with the phosphopeptide docking sites displayed by receptors, dimerization and subsequent DNA binding. The goal of this project is to find a Novel Inhibitor of the Coiled-coil Domain of STAT3 Signaling Pathway against Cancer and develop a useful theoretical foundation in drug design for targeting STAT3.After structure-based screening we detected the activity of these compounds by fluorescence polarization (FP). We also identified that K116 inhibits the growth of tumor cells harboring abnormal activation of STAT3, such as, MDA-MB-468，MDA-MB-231 and DU145. The binding affinity of K116 to CCD and WT of STAT3 are 3.2μM and 2.397μM. Our studies indicate that K116 binds to STAT3 Coiled-coil domain, and we also detect the binding affinity of inhibitors and mutants. Based on these data, we analysis the SAR for optimizing the inhibitors. Meanwhile, we plan to detect the phosphorylation level of 705 Tyr on STAT3, Src, STAT1, STAT5 and downstream targets of STAT3, such as Cyclin D1, C-myc and Bcl-xl in MDA-MB-468 cells in protein level. The suppression of pY705STAT3 nuclear accumulation and migration of MDA-MB-468 cell will also be testing. Finally, we expect the inhibitors induce MDA-MB-468 cell apoptosis and inhibit the growth of tumor in tumor xenografts mouse. Here we aimed to identify a series novel allosteric inhibitors targeted to Coiled-coil domain of STAT3.