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Identification, structure modification, and characterization of potential small-molecule SGK3 inhibitors with novel scaffolds

Authors: Grace Qun Gong1,2,3, Ke Wang4, Xin-Chuan Dai1, Yan Zhou1, Rajesh Basnet1,5, Yi Chen1, De-Hua Yang1, Woo-Jeong Lee2, Christina Maree Buchanan2,3, Jack Urquhart Flanagan3,6, Peter Robin Shepherd2,3, Ying Chen4, Ming-Wei Wang1,4,5
1 The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
2 Department of Molecular Medicine and Pathology, The University of Auckland, Auckland, New Zealand
3 The Maurice Wilkins Centre, Auckland, New Zealand
4 School of Pharmacy, Fudan University, Shanghai 201203, China
5 University of Chinese Academy of Sciences, Beijing 100049, China
6 Auckland Cancer Society Research Centre, Auckland, New Zealand
Correspondence to: Ying Chen: yingchen71@fudan.edu.cn, Ming-Wei Wang: mwwang@simm.ac.cn,
DOI: 10.1038/s41401-018-0087-6
Received: 11 April 2018
Accepted: 10 June 2018
Advance online: 23 July 2018

Abstract

The serum and glucocorticoid-regulated kinase (SGK) family has been implicated in the regulation of many cellular processes downstream of the PI3K pathway. It plays a crucial role in PI3K-mediated tumorigenesis, making it a potential therapeutic target for cancer. SGK family consists of three isoforms (SGK1, SGK2, and SGK3), which have high sequence homology in the kinase domain and similar substrate specificity with the AKT family. In order to identify novel compounds capable of inhibiting SGK3 activity, a high-throughput screening campaign against 50,400 small molecules was conducted using a fluorescence-based kinase assay that has a Z' factor above 0.5. It identified 15 hits (including nitrogen-containing aromatic, flavone, hydrazone, and naphthalene derivatives) with IC50 values in the low micromolar to sub-micromolar range. Four compounds with a similar scaffold (i.e., a hydrazone core) were selected for structural modification and 18 derivatives were synthesized. Molecular modeling was then used to investigate the structure-activity relationship (SAR) and potential protein–ligand interactions. As a result, a series of SGK inhibitors that are active against both SGK1 and SGK3 were developed and important functional groups that control their inhibitory activity identified.
Keywords: serum and glucocorticoid-regulated kinase; SGK3; high-throughput screening; inhibitors; molecular modeling

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