title: Discovery of a small-molecule pBcl-2 inhibitor that overcomes pBcl-2-mediated resistance to apoptosis.
abstract: Although the role of Bcl-2 phosphorylation is still under debate, it has been identified in a resistance mechanism to BH3 mimetics, for example ABT-737 and S1. We identified an S1 analogue, S1-16, as a small-molecule inhibitor of pBcl-2. S1-16 efficiently kills EEE-Bcl-2 (a T69E, S70E, and S87E mutant mimicking phosphorylation)-expressing HL-60 cells and high endogenously expressing pBcl-2 cells, by disrupting EEE-Bcl-2 or native pBcl-2 interactions with Bax and Bak, followed by apoptosis. In vitro binding assays showed that S1-16 binds to the BH3 binding groove of EEE-Bcl-2 (Kd =0.38 μM by ITC; IC50 =0.16 μM by ELISA), as well as nonphosphorylated Bcl-2 (npBcl-2; Kd =0.38 μM; IC50 =0.12 μM). However, ABT-737 and S1 had much weaker affinities to EEE-Bcl-2 (IC50 =1.43 and >10 μM, respectively), compared with npBcl-2 (IC50 =0.011 and 0.74 μM, respectively). The allosteric effect on BH3 binding groove by Bcl-2 phosphorylation in the loop region was illustrated for the first time.
authors.affiliation: State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology, Dalian 116024 (P. R. China).
authors.forename: Ting
authors.initials: T
authors.lastname: Song
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Yu
authors.forename: Yubo
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiangqian
authors.initials: X
authors.lastname: Li
authors.forename: Gaobo
authors.initials: G
authors.lastname: Chai
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D055808:Drug Discovery; D057809:HEK293 Cells; D018922:HL-60 Cells; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008958:Models, Molecular; D015394:Molecular Structure; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000172:deficiency / Q000378:metabolism*; D054852:Small Molecule Libraries / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D054852:Small Molecule Libraries
keywords: BH3 mimetics; Bcl-2; apoptosis; cancer; immunoassays; inhibitors