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Discovery of novel CBP bromodomain inhibitors through TR-FRET-based high-throughput screening

Authors: Feng-cai Zhang1, Zhong-ya Sun2,3, Li-ping Liao3,4, Yu Zuo1,3, Dan Zhang3,5, Jun Wang3,6, Yan-tao Chen3,4, Sen-hao Xiao3,4, Hao Jiang3,4, Tian Lu3,6, Pan Xu3,4, Li-yan Yue3, Dao-hai Du3,6, Hao Zhang3, Chuan-peng Liu2, Cheng Luo3,5,6
1 School of Pharmacy, Nanchang University, Nanchang 330006, China
2 School of Life and Technology, Harbin Institute of Technology, Harbin 150001, China
3 Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
4 University of Chinese Academy of Sciences, Beijing 100049, China
5 Department of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
6 Jiangsu Key Laboratory for High Technology Research of TCM Formulae, Nanjing University of Chinese Medicine, Nanjing 210023, China
Correspondence to: Chuan-peng Liu: liucp74@hotmail.com, Cheng Luo: cluo@simm.ac.cn,
DOI: 10.1038/s41401-019-0256-2
Received: 18 January 2019
Accepted: 16 May 2019
Advance online: 21 May 2019

Abstract

The cAMP-responsive element binding protein (CREB) binding protein (CBP) and adenoviral E1A-binding protein (P300) are two closely related multifunctional transcriptional coactivators. Both proteins contain a bromodomain (BrD) adjacent to the histone acetyl transferase (HAT) catalytic domain, which serves as a promising drug target for cancers and immune system disorders. Several potent and selective small-molecule inhibitors targeting CBP BrD have been reported, but thus far small-molecule inhibitors targeting BrD outside of the BrD and extraterminal domain (BET) family are especially lacking. Here, we established and optimized a TR-FRET-based high-throughput screening platform for the CBP BrD and acetylated H4 peptide. Through an HTS assay against an in-house chemical library containing 20 000 compounds, compound DC_CP20 was discovered as a novel CBP BrD inhibitor with an IC50 value of 744.3 nM. This compound bound to CBP BrD with a KD value of 4.01 μM in the surface plasmon resonance assay. Molecular modeling revealed that DC_CP20 occupied the Kac-binding region firmly through hydrogen bonding with the conserved residue N1168. At the celluslar level, DC_CP20 dose-dependently inhibited the proliferation of human leukemia MV4-11 cells with an IC50 value of 19.2 μM and markedly downregulated the expression of the c-Myc in the cells. Taken together, the discovery of CBP BrD inhibitor DC_CP20 provides a novel chemical scaffold for further medicinal chemistry optimization and a potential chemical probe for CBP-related biological function research. In addition, this inhibitor may serve as a promising therapeutic strategy for MLL leukemia by targeting CBP BrD protein.
Keywords: CBP bromodomain; small-molecule inhibitor; high-throughput screening; TR-FRET; molecular modeling; human leukemia MV4-11 cells

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