糖原合成酶激酶-3和细胞周期蛋白依赖性激酶抑制剂paullones的研究进展

对抑制剂paullones的来源、合成,以及与激酶相互作用的分子机理、选择性、细胞效应进行了综述.指出糖原合成酶激酶-3(GSK-3)是参与糖代谢的主要限速酶之一,人类多种疾病均与其活性调节异常有关;细胞周期蛋白依赖性激酶(CDKs)是一类丝氨酸/苏氨酸蛋白激酶,能够促使细胞进行有序的生长、增殖、休眠或进入凋亡.以CDKs为靶点的药物可以阻断细胞周期,控制癌细胞增殖,从而达到抗肿瘤的目的.Paullones对CDKs和GSK-3均具有良好的选择性,是CDKs和GSK-3的有效抑制剂;迄今为止,文献报道的paullones化合物接近120个.     

Structure-based design leads to the identification of lithium mimetics that block mania-like effects in rodents. possible new GSK-3beta therapies for bipolar disorders

More than two million American adults, or approximately one percent of the population 18 years or older, suffer from bipolar disorder. Current treatments include the so-called "mood stabilizers," lithium and valproic acid. Both are relatively dated drugs that are only partially effective and produce various undesirable side effects including weight gain. Based upon continued efforts to understand the molecular target for lithium, it now appears that specific inhibitors of the enzyme glycogen synthase kinase-3beta (GSK-3beta) may mimic the therapeutic action of mood stabilizers and might therefore allow for the design of improved drugs for treating patients with bipolar disorder as well as certain neurodegenerative disorders. Furthermore, the pro-apoptotic properties of the GSK-3 enzyme suggest the possible use of such inhibitors as neuroprotective agents. In fact, neuroprotection may contribute to the treatment of mood disorders. The present chemistry, modeling, and biology efforts have identified 3-benzofuranyl-4-indolylmaleimides as potent and relatively selective GSK-3beta inhibitors. The best ligand in this series (having a Ki value of 4.6 nM against GSK-3beta) was studied in a novel mouse model of mania that has recently been validated with several clinically effective mood stabilizers. This study presents the first demonstration of the efficacy of a GSK-3beta inhibitor in this mouse model of mania. Selective brain penetrable GSK-3 ligands like those described herein become valuable research tools in better defining the role of this multifaceted kinase in both physiological and pathophysiological events.     

Inhibition of cyclin-dependent kinases, GSK-3beta and CK1 by hymenialdisine, a marine sponge constituent

BACKGROUND: Over 2000 protein kinases regulate cellular functions. Screening for inhibitors of some of these kinases has already yielded some potent and selective compounds with promising potential for the treatment of human diseases. RESULTS: The marine sponge constituent hymenialdisine is a potent inhibitor of cyclin-dependent kinases, glycogen synthase kinase-3beta and casein kinase 1. Hymenialdisine competes with ATP for binding to these kinases. A CDK2-hymenialdisine complex crystal structure shows that three hydrogen bonds link hymenialdisine to the Glu81 and Leu83 residues of CDK2, as observed with other inhibitors. Hymenialdisine inhibits CDK5/p35 in vivo as demonstrated by the lack of phosphorylation/down-regulation of Pak1 kinase in E18 rat cortical neurons, and also inhibits GSK-3 in vivo as shown by the inhibition of MAP-1B phosphorylation. Hymenialdisine also blocks the in vivo phosphorylation of the microtubule-binding protein tau at sites that are hyperphosphorylated by GSK-3 and CDK5/p35 in Alzheimer's disease (cross-reacting with Alzheimer's-specific AT100 antibodies). CONCLUSIONS: The natural product hymenialdisine is a new kinase inhibitor with promising potential applications for treating neurodegenerative disorders.     

Enhanced selectivity for inhibition of analog-sensitive protein kinases through scaffold optimization

The ability to inhibit any protein kinase of interest with a small molecule is enabled by a combination of genetics and chemistry. Genetics is used to modify the active site of a single kinase to render it distinct from all naturally occurring kinases. Next, organic synthesis is used to develop a small molecule, which does not bind to wild-type kinases but is a potent inhibitor of the engineered kinase. This approach, termed chemical genetics, has been used to generate highly potent mutant kinase-specific inhibitors based on a pyrazolopyrimidine scaffold. Here, we asked if the selectivity of the resulting pyrazolopyrimidines could be improved, as they inhibit several wild-type kinases with low-micromolar IC₅₀ values. Our approach to improve the selectivity of allele-specific inhibitors was to explore a second kinase inhibitor scaffold. A series of 6,9-disubstituted purines was designed, synthesized, and evaluated for inhibitory activity against several kinases in vitro and in vivo. Several purines proved to be potent inhibitors against the analog-sensitive kinases and exhibited greater selectivity than the existing pyrazolopyrimidines.     

GSK-3抑制剂研究进展

糖原合成酶激酶-3 (Glycogen synthase kinase-3, GSK-3)是一个多功能的丝氨酸/苏氨酸蛋白激酶,不仅参与肝糖代谢过程,而且还参与Wnt和Hedgehog信号通路,通过磷酸化多种底物蛋白来调节细胞的生理过程。GSK-3抑制剂作为目前倍受关注的小分子抑制剂,对治疗神经退化性疾病,癌症,II型糖尿病具有潜在的疗效。本文针对已开发出的GSK-3抑制剂,对其结构,与蛋白的作用模式以及构效关系进行阐述,为进一步设计合理的药物先导化合物和特异性小分子化学探针提供有益的启示。     

Unique Cyclin-Dependent Kinase (CDK) Inhibitors at the ATP-site

Control of the cell cycle could be applicable in new approaches for cancer chemotherapy. The cyclin-dependent kinases (CDK's) and their corresponding complexes with cyclins are regulatory enzymes for which we have discovered a novel small molecule series of inhibitors, with potencies in the nanomolar range and good selectivity for the CDK's versus other kinases. We will discuss structure-based drug design efforts with crystal structures of complexes with certain CDK's. Cellular effects and some preliminary examination of in vivo cancer efficacy by these inhibitors will also be discussed.     

GSK-3-selective inhibitors derived from Tyrian purple indirubins

Gastropod mollusks have been used for over 2500 years to produce the "Tyrian purple" dye made famous by the Phoenicians. This dye is constituted of mixed bromine-substituted indigo and indirubin isomers. Among these, the new natural product 6-bromoindirubin and its synthetic, cell-permeable derivative, 6-bromoindirubin-3'-oxime (BIO), display remarkable selective inhibition of glycogen synthase kinase-3 (GSK-3). Cocrystal structure of GSK-3beta/BIO and CDK5/p25/indirubin-3'-oxime were resolved, providing a detailed view of indirubins' interactions within the ATP binding pocket of these kinases. BIO but not 1-methyl-BIO, its kinase inactive analog, also inhibited the phosphorylation on Tyr276/216, a GSK-3alpha/beta activation site. BIO but not 1-methyl-BIO reduced beta-catenin phosphorylation on a GSK-3-specific site in cellular models. BIO but not 1-methyl-BIO closely mimicked Wnt signaling in Xenopus embryos. 6-bromoindirubins thus provide a new scaffold for the development of selective and potent pharmacological inhibitors of GSK-3.     

The structure of JNK3 in complex with small molecule inhibitors: structural basis for potency and selectivity

The c-Jun terminal kinases (JNKs) are members of the mitogen-activated protein (MAP) kinase family and regulate signal transduction in response to environmental stress. Activation of JNK3, a neuronal-specific isoform, has been associated with neurological damage, and as such, JNK3 may represent an attractive target for the treatment of neurological disorders. The MAP kinases share between 50% and 80% sequence identity. In order to obtain efficacious and safe compounds, it is necessary to address the issues of potency and selectivity. We report here four crystal structures of JNK3 in complex with three different classes of inhibitors. These structures provide a clear picture of the interactions that each class of compound made with the kinase. Knowledge of the atomic interactions involved in these diverse binding modes provides a platform for structure-guided modification of these compounds, or the de novo design of novel inhibitors that could satisfy the need for potency and selectivity.     

Selective small molecule inhibitors of glycogen synthase kinase-3 modulate glycogen metabolism and gene transcription

BACKGROUND: Glycogen synthase kinase-3 (GSK-3) is a serine/threonine protein kinase, the activity of which is inhibited by a variety of extracellular stimuli including insulin, growth factors, cell specification factors and cell adhesion. Consequently, inhibition of GSK-3 activity has been proposed to play a role in the regulation of numerous signalling pathways that elicit pleiotropic cellular responses. This report describes the identification and characterisation of potent and selective small molecule inhibitors of GSK-3. RESULTS: SB-216763 and SB-415286 are structurally distinct maleimides that inhibit GSK-3alpha in vitro, with K(i)s of 9 nM and 31 nM respectively, in an ATP competitive manner. These compounds inhibited GSK-3beta with similar potency. However, neither compound significantly inhibited any member of a panel of 24 other protein kinases. Furthermore, treatment of cells with either compound stimulated responses characteristic of extracellular stimuli that are known to inhibit GSK-3 activity. Thus, SB-216763 and SB-415286 stimulated glycogen synthesis in human liver cells and induced expression of a beta-catenin-LEF/TCF regulated reporter gene in HEK293 cells. In both cases, compound treatment was demonstrated to inhibit cellular GSK-3 activity as assessed by activation of glycogen synthase, which is a direct target of this kinase. CONCLUSIONS: SB-216763 and SB-415286 are novel, potent and selective cell permeable inhibitors of GSK-3. Therefore, these compounds represent valuable pharmacological tools with which the role of GSK-3 in cellular signalling can be further elucidated. Furthermore, development of similar compounds may be of use therapeutically in disease states associated with elevated GSK-3 activity such as non-insulin dependent diabetes mellitus and neurodegenerative disease.     

Synthesis and biological evaluation of synthetic viridins derived from C(20)-heteroalkylation of the steroidal PI-3-kinase inhibitor wortmannin

A series of viridin analogs was prepared from wortmannin by nucleophilic ring opening at C(20) and evaluated against the signaling kinases PI-3-kinase and mTOR. Several subnanomolar enzyme inhibitors with orders of magnitude selectivity for PI-3-kinase and strong cytotoxic activity against four cancer cell lines were identified. Among the ten most promising derivatives, six demonstrated lower liver toxicity and greater promise for inhibition of tumor cell growth than the lead structure wortmannin.     

Identification of polyoxometalates as nanomolar noncompetitive inhibitors of protein kinase CK2

Protein kinase CK2 is a multifunctional kinase of medical importance that is dysregulated in many cancers. In this study, polyoxometalates were identified as original CK2 inhibitors. [P2Mo18O62](6-) has the most potent activity. It inhibits the kinase in the nanomolar range by targeting key structural elements located outside the ATP- and peptide substrate-binding sites. Several polyoxometalate derivatives exhibit strong inhibitory efficiency, with IC50 values < or = 10 nM. Furthermore, these inorganic compounds show a striking specificity for CK2 when tested in a panel of 29 kinases. Therefore, polyoxometalates are effective CK2 inhibitors in terms of both efficiency and selectivity and represent nonclassical kinase inhibitors that interact with CK2 in a unique way. This binding mode may provide an exploitable mechanism for developing potent drugs with desirable properties, such as enhanced selectivity relative to ATP-mimetic inhibitors.     

Recent Advances in BTK Inhibitors for the Treatment of Inflammatory and Autoimmune Diseases

Bruton’s tyrosine kinase (BTK) plays a crucial role in B-cell receptor and Fc receptor signaling pathways. BTK is also involved in the regulation of Toll-like receptors and chemokine receptors. Given the central role of BTK in immunity, BTK inhibition represents a promising therapeutic approach for the treatment of inflammatory and autoimmune diseases. Great efforts have been made in developing BTK inhibitors for potential clinical applications in inflammatory and autoimmune diseases. This review covers the recent development of BTK inhibitors at preclinical and clinical stages in treating these diseases. Individual examples of three types of inhibitors, namely covalent irreversible inhibitors, covalent reversible inhibitors, and non-covalent reversible inhibitors, are discussed with a focus on their structure, bioactivity and selectivity. Contrary to expectations, reversible BTK inhibitors have not yielded a significant breakthrough so far. The development of covalent, irreversible BTK inhibitors has progressed more rapidly. Many candidates entered different stages of clinical trials; tolebrutinib and evobrutinib are undergoing phase 3 clinical evaluation. Rilzabrutinib, a covalent reversible BTK inhibitor, is now in phase 3 clinical trials and also offers a promising future. An analysis of the protein–inhibitor interactions based on published co-crystal structures provides useful clues for the rational design of safe and effective small-molecule BTK inhibitors.     

Resorcylic acid lactones: A pluripotent scaffold with therapeutic potential

The recent discoveries of potent HSP90 and MAP kinase inhibitors amongst the resorcylic acid lactones (RALs) have revived interest in this family of natural products. Both HSP90 and MAP kinase inhibition hold tremendous therapeutic potential, particularly in the treatment of cancer. Our synthetic efforts towards the RALs and, in particular, selective inhibitors of HSP90 and kinases are reviewed.     

Protein Alpha Shape Similarity Analysis (PASSA): a new method for mapping protein binding sites. Application in the design of a selective inhibitor of tyrosine kinase 2

We have developed a method that we have called Protein Alpha Shape Similarity Analysis (PASSA), that identifies interaction sites that can be utilised to achieve selectivity towards a protein. We have shown that this method is able to identify residues of tyrosine kinases that interact with known selective inhibitors using the following test cases: Abelson (Abl) kinase in complex with STI-571 and Janus kinase 2 (Jak2) in complex with AG-490. The 3D structures of the tyrosine kinase domains of Tyrosine kinase 2 (Tyk2) and Jak2 have been predicted by homology modelling. Computational docking of AG-490 and a set of tyrphostins known not to inhibit Jak2 indicated that our homology models are able to separate inhibitors from non-inhibitors. PASSA has also been used to identify unique properties of Tyk2. According to our results, interactions with hydrogen acceptors and donors on the following residues can be utilised to achieve selectivity towards Tyk2: Y955, E1053, D1062 and S1063. These residues are placed close to non-conserved hydrophobic pockets. The PASSA results, together with results from Multiple Copy Simultaneous Search (MCSS) were used to suggest functional groups of a selective Tyk2 inhibitor.     

Polyprenyl-hydroquinones and -furans from three marine sponges inhibit the cell cycle regulating phosphatase CDC25A

The CDC25 phosphatases regulate the cell division cycle by controlling the activity of cyclin-dependent kinases. While screening for inhibitors of phosphatases among natural products we repeatedly found that some polyprenyl-hydroquinones and polyprenyl-furans (furanoterpenoids) (furospongins, furospinosulins) were potent CDC25 phosphatase inhibitors. These compounds were extracted, isolated and identified independently from three sponge species (Spongia officinalis, Ircinia spinulosa, Ircinia muscarum), collected at different locations in the Mediterranean Sea. The compounds were inactive on the Ser/Thr phosphatase PP2C-alpha and on three kinases (CDK1, CDK5, GSK-3), suggesting that some potent and selective CDC25 phosphatase might be designed from these initial structures.     

New leads for selective GSK-3 inhibition: pharmacophore mapping and virtual screening studies

Summary Glycogen Synthase Kinase-3 is a regulatory serine/threonine kinase, which is being targeted for the treatment of a number of human diseases including type-2 diabetes mellitus, neurodegenerative diseases, cancer and chronic inflammation. Selective GSK-3 inhibition is an important requirement owing to the possibility of side effects arising from other kinases. A pharmacophore mapping strategy is employed in this work to identify new leads for selective GSK-3 inhibition. Ligands known to show selective GSK-3 inhibition were employed in generating a pharmacophore map using distance comparison method (DISCO). The derived pharmacophore map was validated using (i) important interactions involved in selective GSK-3 inhibitions, and (ii) an in-house database containing different classes of GSK-3 selective, non-selective and inactive molecules. New Lead identification was carried out by performing virtual screening using validated pharmacophoric query and three chemical databases namely NCI, Maybridge and Leadquest. Further data reduction was carried out by employing virtual filters based on (i) Lipinski’s rule of 5 (ii) van der Waals bumps and (iii) restricting the number of rotatable bonds to seven. Final screening was carried out using FlexX based molecular docking study.     

Furo[2,3‐d]pyrimidines and Oxazolo[5,4‐d]pyrimidines as Inhibitors of Receptor Tyrosine Kinases (RTK)

Receptor tyrosine kinases such as VEGFR2 (vascular endothelial growth factor receptor 2, KDR) or EGFR (epidermal growth factor receptor) play crucial roles in a variety of diseases, such as cancer. Recently, some pyrrolopyrimidines were shown to be potent EGFR inhibitors. Therefore, new types of oxazolo[5,4‐d]pyrimidines and furo[2,3‐d]pyrimidines were synthesized (Schemes 1 and 2). Appropriately substituted derivatives of these classes of compounds inhibited VEGFR2 and EGFR with IC₅₀ values in the low nanomolar range (see Table). Generally, the furopyrimidines were somewhat more active than the oxazolopyrimidines. The best inhibitors, 20m, 20p , and 20r , had an IC₅₀ of 3 nM towards EGFR and showed a good selectivity, being distinctly less active towards VEGFR2.     

A new protocol for predicting novel GSK-3β ATP competitive inhibitors

Glycogen synthase kinase 3β (GSK-3β) is a potential therapeutic target for cancer, type-2 diabetes, and Alzheimer's disease. This paper proposes a new lead identification protocol that predicts new GSK-3β ATP competitive inhibitors with topologically diverse scaffolds. First, three-dimensional quantitative structure-activity relationship (3D QSAR) models were built and validated. These models are based upon known GSK-3β inhibitors, benzofuran-3-yl-(indol-3-yl) maleimides, by means of comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Second, 28?826 maleimide derivatives were selected from the PubChem database. After filtration via Lipinski's rules, 10?429 maleimide derivatives were left. Third, the FlexX-dock program was employed to virtually screen the 10?429 compounds against GSK-3β. This resulted in 617 virtual hits. Fourth, the 3D QSAR models predicted that from the 617 virtual hits, 93 compounds would have GSK-3β inhibition values of less than 15 nM. Finally, from the 93 predicted active hits, 23 compounds were confirmed as GSK-3β inhibitors from literatures; their GSK-3β inhibition ranged from 1.3 to 480 nM. Therefore, the hits rate of our virtual screening protocol is greater than 25%. The protocol combines ligand- and structure-based approaches and therefore validates both approaches and is capable of identifying new hits with topologically diverse scaffolds.     

A cell-based screening method for specifically detecting kinase activity

No universal approach has been reported for specific monitoring of the catalytic activity of a wide range of kinases in cells. The present study describes an original platform for detecting the autonomous activity of serine/threonine kinases in cells through the introduction of expression vectors encoding modified substrate kinase fusion proteins. The surrogate substrate used consists of the p53 tumor suppressor protein fused with individual kinase domains (Chk1, DYRK3, and Cdk5) at its carboxy-terminal through four tandem Gly-Gly-Gly-Gly-Ser repeats. After transfection into cells, phosphorylation of the p53 moiety could be specifically induced by the catalytic activity of kinases contained in the fusion protein. Moreover, p53 phosphorylation was significantly blocked when a kinase-inactive mutant was used as the fusion partner instead of the active kinase. Using this system, the cell-based evaluation of several Cdk5 inhibitors was demonstrated. Thus, this approach provides a novel platform for the specific, cell-based screening of inhibitors of a wide prospective range of protein kinases and is of tremendous potential for drug discovery efforts.     

Development of CDK4/6 Inhibitors: A Five Years Update

The inhibition of cyclin dependent kinases 4 and 6 plays a role in aromatase inhibitor resistant metastatic breast cancer. Three dual CDK4/6 inhibitors have been approved for the breast cancer treatment that, in combination with the endocrine therapy, dramatically improved the survival outcomes both in first and later line settings. The developments of the last five years in the search for new selective CDK4/6 inhibitors with increased selectivity, treatment efficacy, and reduced adverse effects are reviewed, considering the small-molecule inhibitors and proteolysis-targeting chimeras (PROTACs) approaches, mainly pointing at structure-activity relationships, selectivity against different kinases and antiproliferative activity.