Szelag Malgorzata, Czerwoniec Anna, Wesoly Joanna, Bluyssen Hans A R
Department of Human Molecular Genetics, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University in Poznan, Umultowska 89, 61-614 Poznan, Poland.
Bioinformatics Laboratory, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University in Poznan, Umultowska 89, 61-614 Poznan, Poland.
PLoS One. 2015 Feb 24;10(2):e0116688. doi: 10.1371/journal.pone.0116688. eCollection 2015.
Signal transducers and activators of transcription (STATs) facilitate action of cytokines, growth factors and pathogens. STAT activation is mediated by a highly conserved SH2 domain, which interacts with phosphotyrosine motifs for specific STAT-receptor contacts and STAT dimerization. The active dimers induce gene transcription in the nucleus by binding to a specific DNA-response element in the promoter of target genes. Abnormal activation of STAT signaling pathways is implicated in many human diseases, like cancer, inflammation and auto-immunity. Searches for STAT-targeting compounds, exploring the phosphotyrosine (pTyr)-SH2 interaction site, yielded many small molecules for STAT3 but sparsely for other STATs. However, many of these inhibitors seem not STAT3-specific, thereby questioning the present modeling and selection strategies of SH2 domain-based STAT inhibitors. We generated new 3D structure models for all human (h)STATs and developed a comparative in silico docking strategy to obtain further insight into STAT-SH2 cross-binding specificity of a selection of previously identified STAT3 inhibitors. Indeed, by primarily targeting the highly conserved pTyr-SH2 binding pocket the majority of these compounds exhibited similar binding affinity and tendency scores for all STATs. By comparative screening of a natural product library we provided initial proof for the possibility to identify STAT1 as well as STAT3-specific inhibitors, introducing the 'STAT-comparative binding affinity value' and 'ligand binding pose variation' as selection criteria. In silico screening of a multi-million clean leads (CL) compound library for binding of all STATs, likewise identified potential specific inhibitors for STAT1 and STAT3 after docking validation. Based on comparative virtual screening and docking validation, we developed a novel STAT inhibitor screening tool that allows identification of specific STAT1 and STAT3 inhibitory compounds. This could increase our understanding of the functional role of these STATs in different diseases and benefit the clinical need for more drugable STAT inhibitors with high specificity, potency and excellent bioavailability.
信号转导子和转录激活子（STATs）促进细胞因子、生长因子和病原体的作用。STAT的激活由一个高度保守的SH2结构域介导，该结构域与磷酸酪氨酸基序相互作用，以实现特定的STAT-受体接触和STAT二聚化。活性二聚体通过与靶基因启动子中的特定DNA反应元件结合，在细胞核中诱导基因转录。STAT信号通路的异常激活与许多人类疾病有关，如癌症、炎症和自身免疫。针对STAT的化合物搜索，探索磷酸酪氨酸（pTyr）-SH2相互作用位点，产生了许多针对STAT3的小分子，但针对其他STAT的则很少。然而，这些抑制剂中的许多似乎并非STAT3特异性的，从而对基于SH2结构域的STAT抑制剂目前的建模和选择策略提出了质疑。我们为所有人类（h）STATs生成了新的三维结构模型，并开发了一种比较性的计算机对接策略，以进一步深入了解所选先前鉴定的STAT3抑制剂的STAT-SH2交叉结合特异性。事实上，通过主要靶向高度保守的pTyr-SH2结合口袋，这些化合物中的大多数对所有STATs表现出相似的结合亲和力和趋势得分。通过对天然产物库的比较筛选，我们为鉴定STAT1以及STAT3特异性抑制剂的可能性提供了初步证据，引入了“STAT比较结合亲和力值”和“配体结合姿势变化”作为选择标准。对一个包含数百万个纯净先导（CL）化合物库进行计算机筛选，以筛选所有STATs的结合情况，同样在对接验证后鉴定出了STAT1和STAT3的潜在特异性抑制剂。基于比较虚拟筛选和对接验证，我们开发了一种新型的STAT抑制剂筛选工具，可用于鉴定特异性STAT1和STAT3抑制化合物。这可以增进我们对这些STATs在不同疾病中的功能作用的理解，并满足临床对具有高特异性、高效力和优异生物利用度的更多可成药STAT抑制剂的需求。
