Drug Discovery Targeting Tumor Energy Metabolism Pathways

This article consists of two chapters,the first chapter aimed to introduce the discovery process of an anti-tumor compound PSBK targeting kidney-type glutaminase(KGA)and evaluate its activity in vitro and in vivo.Chapter II was sought to apply virtual screening-based docking method to identify HK2 inhibitors from natural product.Chapter 1Kidney-type glutaminase(KGA),a mitochondrial enzyme converting glutamine to glutamate for energy supply,was over-expressed in many cancers and had been regarded as a promising therapeutic target in recent years.Structure-based virtual ligand screening predicted physapubescin K,a new withanolide from Physalis pubescens,to be potential KGA inhibitor.Enzyme activity inhibition assays and microscale thermophoresis experiments had demonstrated the efficiency and specificity of physapubescin K targeting KGA.Additionally,physapubescin K exhibited potent proliferation inhibitory effects on a panel of human cancer cell lines,such as SW1990 and HCC827-ER.It blocked glutamine metabolism in SW1990 with increasing intracellular level of glutamine and decreasing glutamate and its downstream metabolites.Physapubescin K also significantly inhibited the tumor growth in a SW1990 xenograft mouse model.Interestingly,physapubescin K could reverse the resistance of HCC827-ER cells to erlotinib and synergize with the hexokinase 2 inhibitor to markedly enhance the inhibition of SW1990 cell proliferation.Chapter 2Hexokinase 2(HK2),a rate-limiting enzyme in the first step of glycolysis pathway,expresses at high level in cancer cells compared with normal cells.HK2 provides a new target for cancer therapy due to its pivotal role in tumor tumourigenic and metastatic process.The structure-based virtual ligand screening in a small in-house database of natural products predicted that a new steroid,(22E,24R)-6β-methoxyergosta-7,9(11),22-triene-3β,5α-diol(2)from Ganoderma sinense has high binding affinity to HK2 with significant calculated binding free energy.Based on this prediction,compound 2,together with the other 12 steroid analogues(1,3-13)from this plant were selected for further in vitro MST,enzyme inhibition,and cell-based assays based on the HK2 target.And compound 2 was finally identified as an HK2 inhibitor.As the first natural HK2 inhibitor,compound 2 can be considered as a potential drug candidate targeting at HK2 for cancer therapy.