title: Rational development of Stafib-2: a selective, nanomolar inhibitor of the transcription factor STAT5b.
abstract: The transcription factor STAT5b is a target for tumour therapy. We recently reported catechol bisphosphate and derivatives such as Stafib-1 as the first selective inhibitors of the STAT5b SH2 domain. Here, we demonstrate STAT5b binding of catechol bisphosphate by solid-state nuclear magnetic resonance, and report on rational optimization of Stafib-1 (Ki= 44 nM) to Stafib-2 (Ki= 9 nM). The binding site of Stafib-2 was validated using combined isothermal titration calorimetry (ITC) and protein point mutant analysis, representing the first time that functional comparison of wild-type versus mutant protein by ITC has been used to characterize the binding site of a small-molecule ligand of a STAT protein with amino acid resolution. The prodrug Pomstafib-2 selectively inhibits tyrosine phosphorylation of STAT5b in human leukaemia cells and induces apoptosis in a STAT5-dependent manner. We propose Pomstafib-2, which currently represents the most active, selective inhibitor of STAT5b activation available, as a chemical tool for addressing the fundamental question of which roles the different STAT5 proteins play in various cell processes.
authors.affiliation: Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Nagarajan
authors.initials: N
authors.lastname: Elumalai
authors.affiliation: Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Berg
authors.affiliation: Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rubner
authors.affiliation: Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Blechschmidt
authors.affiliation: Institute of Analytical Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany.|Leids Instituut voor Chemisch Onderzoek, Universiteit Leiden, 2300 RA, Leiden, The Netherlands.
authors.forename: Chen
authors.identifier: http://orcid.org/0000-0003-1034-5881
authors.initials: C
authors.lastname: Song
authors.affiliation: Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Kalaiselvi
authors.initials: K
authors.lastname: Natarajan
authors.affiliation: Institute of Analytical Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Matysik
authors.affiliation: Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany. tberg@uni-leipzig.de.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Berg
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites; D002396:Catechols / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D006801:Humans; D062105:Molecular Docking Simulation; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D021281:Quantitative Structure-Activity Relationship; D050799:STAT5 Transcription Factor / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D000970:Antineoplastic Agents; D002396:Catechols; D050799:STAT5 Transcription Factor; C494095:STAT5B protein, human; C000628246:Stafib-2