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Discovery of a Small‐Molecule pBcl‐2 Inhibitor that Overcomes pBcl‐2‐Mediated Resistance to Apoptosis
Author(s) -
Song Ting,
Yu Xiaoyan,
Liu Yubo,
Li Xiangqian,
Chai Gaobo,
Zhang Zhichao
Publication year - 2015
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201402639
Subject(s) - phosphorylation , allosteric regulation , apoptosis , in vitro , chemistry , mutant , stereochemistry , small molecule , microbiology and biotechnology , biophysics , biochemistry , biology , receptor , gene
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 ( K d =0.38 μ M by ITC; IC 50 =0.16 μ M by ELISA), as well as nonphosphorylated Bcl‐2 (npBcl‐2; K d =0.38 μ M ; IC 50 =0.12 μ M ). However, ABT‐737 and S1 had much weaker affinities to EEE‐Bcl‐2 (IC 50 =1.43 and >10 μ M , respectively), compared with npBcl‐2 (IC 50 =0.011 and 0.74 μ M , respectively). The allosteric effect on BH3 binding groove by Bcl‐2 phosphorylation in the loop region was illustrated for the first time.