Stafia‐1: a STAT5a‐Selective Inhibitor Developed via Docking‐Based Screening of in Silico O‐Phosphorylated Fragments

• Published in: Chemistry : a European journal 2020-01, Vol.26 (1), p.148-154
• Main Authors: Natarajan, Kalaiselvi, Müller‐Klieser, Daniel, Rubner, Stefan, Berg, Thorsten
• Format: Article
• Language: English
• Subjects: Binding Sites; biological activity; Biological Products - chemistry; Cell Line, Tumor; Cell Survival - drug effects; Chemistry; Communication; Communications; Docking; Fragments; Homology; Humans; Inhibitors; Leukemia; Molecular Docking Simulation; Natural products; Organophosphonates - chemistry; Organophosphonates - metabolism; Organophosphonates - pharmacology; Phenolic compounds; Phenols; Phosphonates; Phosphorylation; Prodrugs - chemistry; Prodrugs - metabolism; Proteins; protein–protein interactions; Screening; Selectivity; SH2 domains; src Homology Domains; Stat3 protein; STAT5 Transcription Factor - antagonists & inhibitors; STAT5 Transcription Factor - metabolism; Structure-Activity Relationship; transcription factors; Tumor Suppressor Proteins - antagonists & inhibitors; Tumor Suppressor Proteins - metabolism
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201904147

We present a new approach for the identification of inhibitors of phosphorylation‐dependent protein–protein interaction domains, in which phenolic fragments are adapted by in silico O‐phosphorylation before docking‐based screening. From a database of 10 369 180 compounds, we identified 85 021 natural product‐derived phenolic fragments, which were virtually O‐phosphorylated and screened for in silico binding to the STAT3 SH2 domain. Nine screening hits were then synthesized, eight of which showed a degree of in vitro inhibition of STAT3. After analysis of its selectivity profile, the most potent inhibitor was then developed to Stafia‐1, the first small molecule shown to preferentially inhibit the STAT family member STAT5a over the close homologue STAT5b. A phosphonate prodrug based on Stafia‐1 inhibited STAT5a with selectivity over STAT5b in human leukemia cells, providing the first demonstration of selective in vitro and intracellular inhibition of STAT5a by a small‐molecule inhibitor. Creating and searching the virtual haystack: In silico O‐phosphorylation of preselected natural product‐related fragments from the SCONP (structural classification of natural products) tree, virtual screening and chemical derivatization enabled the development of Stafia‐1, the first molecule shown to inhibit the transcription factor STAT5a with selectivity over the close homologue STAT5b.