Identification of Novel GSK-3β Inhibitors through Docking Based Virtual Screening and Biological Evaluation

Original Article

Austin J Cancer Clin Res. 2021; 8(1): 1089.

Identification of Novel GSK-3β Inhibitors through Docking Based Virtual Screening and Biological Evaluation

Xu M1#, Gao SY1#, Zeng YX1#, Xu L3, Gao JR1, Li J3, Zhou YB3*, Cheng G2* and Ye Q1*

1Zhejiang University of Technology, State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, China

2Zhejiang Chinese Medicinal University, College of Pharmaceutical Sciences, China

3National Center for Drug Screening, State Key Laboratory of Drug Research, Chinese Academy of Sciences, China

#These two authors contribute equally

*Corresponding author: Yu-Bo Zhou, National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China

Gang Cheng, College of Pharmaceutical Sciences, Zhejiang Chinese Medicinal University, China

Qing Ye, State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, China

Received: April 21, 2021; Accepted: May 11, 2021; Published: May 18, 2021

Abstract

GSK-3β is a key regulator in insulin, Wnt and NF-κB signaling pathways. Dysregulation of GSK-3β is often related to tumors and diabetes. Inhibiting it might provide cure for diabetes, tumors, neurodegeneration and brain ischemia. Although there are a number of reported GSK-3β inhibitors, the scaffold is limited. Herein we report a discriminatory analysis-based molecular docking on the Specs database, and identified 3 novel GSK-3β inhibitors with moderate IC50 (ranging from 17.42 μM to 6.74 μM) in the following in vitro biological test. Further dynamic simulations and docking pose analysis were performed to give a better understanding on the binding conformation of 3 hit compounds AK- 777/09836064, AK-968/37185006 and AN-698/41607072, which would provide basis for further optimization.

Keywords: GSK-3β inhibitors; Molecular docking; Virtual screen; Molecular dynamics

Introduction

Glycogen Synthase Kinase-3 (GSK-3) is a serine/threonine kinase family member, which was initially found to be one of the major rate-limiting enzymes in glucose metabolism. Glycogen synthesis can be inhibited by GSK-3 via phosphorylation of glycogen synthase [1,2]. However, studies over the past 20 years have shown that GSK- 3 is associated with multiple cellular functions including neuronal development [3], transcription [4], as well as cell division [5], survival and death [6,7]. GSK-3 has 2 major isoforms, i.e. GSK-3α and GSK- 3β. GSK-3β is an important component of multiple intracellular signaling pathways and is involved not only in the regulation of the insulin signaling pathway but also in others such as Wnt and NF- κB signaling pathways [8]. Development of many human diseases including diabetes [9], tumors [10], neurodegeneration [11], brain ischemia [12] is associated with abnormality in the regulation of the activity of GSK-3β. And thus, GSK-3β has emerged as a potential target for the treatment of a variety of diseases. The study of GSK-3β functional activity and the development of GSK-3β inhibitors have been actively pursuited. A number of GSK-3β inhibitors have been reported [13,14], and there are 3 main types: (ATP-) competitive inhibitor [15-21], non-competitive inhibitor [22,23] and substrate inhibitor [24-26]. Among them, LY2090314 [27] is an effective and selective ATP-competitive GSK-3 inhibitor for the treatment of acute leukemia, and is under phase II clinical trials for the treatment of leukemia [28]. The safety and effectiveness of 9-ING-41 as a single drug combined with cytotoxic drugs in refractory cancer patients is an ATP-competitive GSK-3 inhibitor currently in phase 1/2 [28]. Tideglusib is a non-ATP-competitive and irreversible GSK- 3β inhibitor, which is currently under phase II clinical trials for the treatment of Alzheimer’s disease [28].

There are a number of GSK-3β inhibitors reported in literatures. However, most of them were restricted to have a five-membered heterocycle core and two aromatic rings. GSK-3β inhibitors with new scaffolds are needed. Computer-aided drug design has shown to be an effective approach to identify novel GSK-3 inhibitors [29]. Recently, various methods have been explored to improve the discriminatory ability of molecular docking [30-32]. Herein, we reported the identification of 3 novel inhibitors of GSK-3β from Specs database through a discriminatory analysis-based molecular docking and in vitro enzymatic experiment. Their IC50 values were determined as 6.74 ± 1.05, 17.42 ± 2.85, and 15.50 ± 1.57 μM, respectively. The binding mode of the most potent compound AN-698/41607072 was also investigated via molecular dynamic simulations, giving important information for further structural modification.

Results

Protein selection

To choose an appropriate PDB [33] structure, both crystal redocking analysis and comparable docking of inhibitors and decoys were performed for 30 protein chains. The resulting “RMSD” value and discrimination capability (p value) were listed in Table 1. Most PDBs successfully restore the near-native conformations of the inhibitors in the crystal complexes (RMSD<2.0Å), except for 2JDO_A, 3E87_A, 3 QKK_A, 3SAY_A, 4PTG_A and 5HLP_A. The discrimination power is the ability of molecular docking to distinguish the known antagonists from the decoys, which is more essential for a practical docking-based VS campaign. As shown in Table 1, half of PDBs have relative low p-value (lower than 1×10- 44), especially five complexes (1Q3D_A, 4PTE_A, 4PTG_A, 6Y9R_A and 6Y9S_A [34]) which have a p-value lower than 1×10-55. The best discrimination power was obtained with 6Y9S_A (p = 4.84×10-59). The docking scores for known inhibitors and decoys with the best two receptors (6Y9R_A and 6Y9S_A) were plotted in Figure 2, in which the known inhibitors (blue columns) could clearly be distinguished from the decoys (yellow columns). Therefore, 6Y9S_A were selected as the grid receptor for following virtual screening campaign.