Synthesis and biological evaluation of thiazole derivatives as novel USP7 inhibitors

Discovery of pyrrolo[2,3-d]pyrimidin-4-one derivative YCH3124 as a potent USP7 inhibitor for cancer therapy

USP7 is one of the most studied deubiquitinating enzymes, which is involved in the regulation of multiple cell signaling pathways and has been shown to be associated with the occurrence and progression of a variety of cancers. Inhibitors targeting USP7 have been studied by several teams, but most of them lack selectivity and have low activities. Herein, we reported a serious of pyrrole[2,3-d]pyrimidin-4-one derivatives through scaffold hopping of recently reported 4-hydroxypiperidine compounds. The representative compound Z33 (YCH3124) exhibited highly potent USP7 inhibition activity as well as anti-proliferative activity against four kinds of cancer cell lines. Further study revealed that YCH3124 effectively inhibited the downstream USP7 pathway and resulted in the accumulation of both p53 and p21 in a dose-dependent manner. Notably, YCH3124 disrupted cell cycle progression through restricting G1 phase and induced significant apoptosis in CHP-212 cells. In summary, our efforts provided a series of novel pyrrole[2,3-d]pyrimidin-4-one analogs as potent USP7 inhibitors with excellent anti-cancer activity.

Molecular mechanisms of aging and anti-aging strategies

Aging is a complex and multifaceted process involving a variety of interrelated molecular mechanisms and cellular systems. Phenotypically, the biological aging process is accompanied by a gradual loss of cellular function and the systemic deterioration of multiple tissues, resulting in susceptibility to aging-related diseases. Emerging evidence suggests that aging is closely associated with telomere attrition, DNA damage, mitochondrial dysfunction, loss of nicotinamide adenine dinucleotide levels, impaired macro-autophagy, stem cell exhaustion, inflammation, loss of protein balance, deregulated nutrient sensing, altered intercellular communication, and dysbiosis. These age-related changes may be alleviated by intervention strategies, such as calorie restriction, improved sleep quality, enhanced physical activity, and targeted longevity genes. In this review, we summarise the key historical progress in the exploration of important causes of aging and anti-aging strategies in recent decades, which provides a basis for further understanding of the reversibility of aging phenotypes, the application prospect of synthetic biotechnology in anti-aging therapy is also prospected.

USP7 as an emerging therapeutic target: A key regulator of protein homeostasis

Maintaining protein balance within a cell is essential for proper cellular function, and disruptions in the ubiquitin-proteasome pathway, which is responsible for degrading and recycling unnecessary or damaged proteins, can lead to various diseases. Deubiquitinating enzymes play a vital role in regulating protein homeostasis by removing ubiquitin chains from substrate proteins, thereby controlling important cellular processes, such as apoptosis and DNA repair. Among these enzymes, ubiquitin-specific protease 7 (USP7) is of particular interest. USP7 is a cysteine protease consisting of a TRAF region, catalytic region, and C-terminal ubiquitin-like (UBL) region, and it interacts with tumor suppressors, transcription factors, and other key proteins involved in cell cycle regulation and epigenetic control. Moreover, USP7 has been implicated in the pathogenesis and progression of various diseases, including cancer, inflammation, neurodegenerative conditions, and viral infections. Overall, characterizing the functions of USP7 is crucial for understanding the pathophysiology of diverse diseases and devising innovative therapeutic strategies. This article reviews the structure and function of USP7 and its complexes, its association with diseases, and its known inhibitors and thus represents a valuable resource for advancing USP7 inhibitor development and promoting potential future treatment options for a wide range of diseases.

Functionalized Gold Nanoparticles Suppress the Proliferation of Human Lung Alveolar Adenocarcinoma Cells by Deubiquitinating Enzymes Inhibition

Functionalized gold nanoparticles (AuNPs) are widely used in therapeutic applications, but little is known regarding the impact of their surface functionalization in the process of toxicity against cancer cells. This study investigates the anticancer effects of 5 nm spherical AuNPs functionalized with tannate, citrate, and PVP on deubiquitinating enzymes (DUBs) in human lung alveolar adenocarcinoma (A549) cells. Our findings show that functionalized AuNPs reduce the cell viability in a concentration- and time-dependent manner as measured by modified lactate dehydrogenase (mLDH) and 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assays. An increased generation of intracellular reactive oxygen species (ROS) and depletion of glutathione (GSH/GSSG) ratio was observed with the highest AuNP concentration of 10 μg/mL. The expression of DUBs such as ubiquitin specific proteases (USP7, USP8, and USP10) was slightly inhibited when treated with concentrations above 2.5 μg/mL. Moreover, functionalized AuNPs showed an inhibitory effect on protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) and wingless-related integration site (Wnt) signaling proteins, and this could further trigger mitochondrial related-apoptosis by the upregulation of caspase-3, caspase-9, and PARP in A549 cells. Furthermore, our study shows a mechanistic understanding of how functionalized AuNPs inhibit the DUBs, consequently suppressing cell proliferation, and can be modulated as an approach toward anticancer therapy. The study also warrants the need for future work to investigate the effect of functionalized AuNPs on DUB on other cancer cell lines both in vitro and in vivo.

USP7 - a crucial regulator of cancer hallmarks

Over the course of three decades of study, the deubiquitinase Herpesvirus associated Ubiquitin-Specific Protease/Ubiquitin-Specific Protease 7 (HAUSP/USP7) has gradually come to be recognized as a crucially important molecule in cellular physiology. The fact that USP7 is overexpressed in a number of cancers, including breast, prostate, colorectal, and lung cancers, supports the idea that USP7 is also an important regulator of tumorigenesis. In this review, we discuss USP7's function in relation to the cancer hallmarks described by Hanahan and Weinberg. This post-translational modifier can support increased proliferation, block unfavorable growth signals, stop cell death, and support an unstable cellular genome by manipulating key players in the pertinent signalling circuit. It is interesting to note that USP7 also aids in the stabilization of molecules that support angiogenesis and metastasis. Targeting USP7 has now emerged as a crucial component of USP7 research because pharmacological inhibition of USP7 supports p53-mediated cell cycle arrest and apoptosis. Efficacious USP7 inhibition is currently being investigated in both synthetic and natural compounds, but issues with selectivity and a lack of co-crystal structure have hindered USP7 inhibition from being tested in clinical settings. Moreover, the development of new, more effective USP7 inhibitors and their encouraging implications by numerous groups give us a glimmer of hope for USP7-targeting medications as effective substitutes for hazardous cancer chemotherapeutics.

Discovery of Orally Bioavailable N-Benzylpiperidinol Derivatives as Potent and Selective USP7 Inhibitors with In Vivo Antitumor Immunity Activity against Colon Cancer

USP7 emerges as a potential therapeutic target for cancers, as it plays an important role in the development of tumorigenesis by stabilizing multiple cancer-relevant proteins. Nevertheless, the discovery of drug-like USP7 inhibitors remains challenging. Herein, we report a series of N-benzylpiperidinol derivatives as potent and selective USP7 inhibitors (e.g., X20 and X26: IC₅₀ = 7.6 and 8.2 nM), whose binding modes were revealed by crystallographic studies to be distinct from the known N-acylpiperidinol USP7 inhibitors. Among them, X36 with good oral PK profiles (rat: F = 40.8% and T_1/2 = 3.5 h) exhibited significant antitumor efficacy in the MC38 colon cancer syngeneic mouse model, at least partly through upregulating the tumor infiltration of CD8⁺ T, NK, and NKT cells and downregulating that of Tregs and MDSCs. These findings may further pave the way for the development of USP7 inhibitors as novel cancer immunotherapy drugs.

Design, synthesis and biological evaluation of 2-aminopyridine derivatives as USP7 inhibitors

A series of novel 2-aminopyridine derivatives 1-26 have been designed and synthesized by structural modifications on a lead USP7 inhibitor, GNE6640. All the compounds were evaluated for their USP7 inhibitory activities. The results showed that most of the compounds have good USP7 inhibitory activities at the concentration of 50 μM. Among them, compounds 7, 14 and 21 are the most potential ones from each category with the IC₅₀ values of 7.6 ± 0.1 μM, 17.0 ± 0.2 μM and 11.6 ± 0.5 μM, respectively. Compounds 7 and 21 expressed significant binding interactions with USP7 by surface plasmon resonance (SPR)-based binding assay, but both of them presented moderate antiproliferative activities against HCT116 cells. They could effectively promote MDM2 degradation, p53 stabilization and p21 gene expression in the western blot analysis.

Discovery of a Potent and Selective Degrader for USP7

The tumor suppressor p53 is the most frequently mutated gene in human cancer and more than half of cancers contain p53 mutations. The development of novel and effective therapeutic strategies for p53 mutant cancer therapy is a big challenge and highly desirable. Ubiquitin-specific protease 7 (USP7), also known as HAUSP, is a deubiquitinating enzyme and proposed to stabilize the oncogenic E3 ubiquitin ligase MDM2 that promotes the proteosomal degradation of p53. Herein, we report the design and characterization of U7D-1 as the first selective USP7-degrading Proteolysis Targeting Chimera (PROTAC). U7D-1 showed selective and effective USP7 degradation, and maintained potent cell growth inhibition in p53 mutant cancer cells, with USP7 inhibitor showing no activity. These data clearly demonstrated the practicality and importance of PROTAC as a preliminary chemical tool for investigating USP7 protein functions and a promising method for potential p53 mutant cancer therapy.

A patent review of ubiquitin-specific protease 7 (USP7) inhibitors (2014-present)

INTRODUCTION

Ubiquitin-specific protease 7 (USP7) plays a critical role in multiple signaling pathways, and many recent studies have proved its association with many diseases. The USP7-murine double minute 2-p53 pathway and the relationship between USP7 and the important immune protein PD-L1 in cancer progression and metastasis have been clarified. Recently, USP7 has emerged as a promising and potent therapeutic target for cancer and has attracted both academic and industrial attention.

AREAS COVERED

This review focuses on the structure, activity, and applications of USP7 inhibitors in cancer therapy. It also focuses on patents reported since 2014.

EXPERT OPINION

Recently, USP7 has attracted considerable attention owing to its physiological and pathophysiological roles in cancer progression, and few studies have focused on the development of USP7 inhibitors. Compared with micromolar first-generation USP7 inhibitors, second-generation USP7 inhibitors exhibit higher potency (at nanomolar level for both USP7 and cell inhibitory activities), higher selectivity, and better pharmacokinetic properties, and they largely broaden the range of candidites for further clinical tests. However, there is still a need for a more precise description of compounds with receptors, the structural diversity of these compounds, and screening methods.

Thiazole and Related Heterocyclic Systems as Anticancer Agents: A Review on Synthetic Strategies, Mechanisms of Action and SAR Studies

Background:

Cancer is the second leading cause of death throughout the world. Many anticancer drugs are commercially available, but lack of selectivity, target specificity, cytotoxicity and development of resistance lead to serious side effects. There have been several experiments going on to develop compounds with minor or no side effects.

Objective:

This review mainly emphasizes synthetic strategies, SAR studies, and mechanism of action for thiazole, benzothiazole, and imidazothiazole containing compounds as anticancer agents.

Methods:

Recent literature related to thiazole and thiazole-related derivatives endowed with encouraging anticancer potential is reviewed. This review emphasizes contemporary strategies used for the synthesis of thiazole and related derivatives, mechanistic targets, and comprehensive structural activity relationship studies to provide perspective into the rational design of high-efficiency thiazole-based anticancer drug candidates.

Results:

Exhaustive literature survey indicated that thiazole derivatives are associated with properties of inducing apoptosis and disturbing tubulin assembly. Thiazoles are also associated with the inhibition of NFkB/mTOR/PI3K/AkT and regulation of estrogen-mediated activity. Furthermore, thiazole derivatives have been found to modulate critical targets such as topoisomerase and HDAC.

Conclusion:

Thiazole derivatives seem to be quite competent and act through various mechanisms. Some of the thiazole derivatives, such as compounds 29, 40, 62, and 74a with IC50 values of 0.05 μM, 0.00042 μM, 0.18 μM, and 0.67 μM, respectively not only have anticancer activity but they also have lower toxicity and better absorption. Therefore, some other similar compounds could be investigated to aid in the development of anticancer pharmacophores.

Synthesis and Antitumor Activity of 5-Phenyl-1,3-thiazole-4-sulfonamide Derivatives

Abstract

A method for the synthesis of 5-phenyl-1,3-thiazole-4-sulfonyl chloride was developed based on the cyclization of ethyl 2-{[1-(benzylsulfanyl)-2-oxo-2-phenylethyl]amino}-2-oxoacetate obtained from available reagents under the action of the Lawesson’s reagent and oxidative chlorination of the intermediate benzyl 5-phenyl-1,3thiazol-4-ylsulfide. The resulting sulfonyl chloride was converted into a series of 5-phenyl-1,3-thiazole-4-sulfonamide derivatives for which in vitro antitumor activity screening studies were performed on 60 cancer cell lines.

Advances in deubiquitinating enzymes in lung adenocarcinoma

The process of ubiquitination and deubiquitination is widely present in the human body's protein reactions and plays versatile roles in multiple diseases. Deubiquitinating enzymes (DUBs) are significant regulators of this process, which cleave the ubiquitin (Ub) moiety from various substrates and maintain protein stability. Lung adenocarcinoma (LUAD) is the most common type of non-small cell lung cancer (NSCLC) and remains refractory to treatment. To elucidate the mechanism of LUAD and advance new therapeutic targets, we review the latest research progress on DUBs in LUAD. We summarize the biological capabilities of these DUBs and further highlight those DUBs that may serve as anticancer target candidates for precision treatment. We also discuss deubiquitinase inhibitors, which are expected to play a role in targeted LUAD therapy.

Targeting Ubiquitin-Specific Protease 7 (USP7) in Cancer: A New Insight to Overcome Drug Resistance

Chemoresistance is one of the leading causes for the failure of tumor treatment. Hence, it is necessary to study further and understand the potential mechanisms of tumor resistance to design and develop novel anti-tumor drugs. Post-translational modifications are critical for proteins’ function under physiological and pathological conditions, among which ubiquitination is the most common one. The protein degradation process mediated by the ubiquitin-proteasome system is the most well-known function of ubiquitination modification. However, ubiquitination also participates in the regulation of many other biological processes, such as protein trafficking and protein-protein interaction. A group of proteins named deubiquitinases can hydrolyze the isopeptide bond and disassemble the ubiquitin-protein conjugates, thus preventing substrate proteins form degradation or other outcomes. Ubiquitin-specific protease 7 (USP7) is one of the most extensively studied deubiquitinases. USP7 exhibits a high expression signature in various malignant tumors, and increased USP7 expression often indicates the poor tumor prognosis, suggesting that USP7 is a marker of tumor prognosis and a potential drug target for anti-tumor therapy. In this review, we first discussed the structure and function of USP7. Further, we summarized the underlying mechanisms by which tumor cells develop resistance to anti-tumor therapies, provided theoretical support for targeting USP7 to overcome drug resistance, and some inspiration for the design and development of USP7 inhibitors.

Design, synthesis, biological evaluation and structure-activity relationship study of quinazolin-4(3H)-one derivatives as novel USP7 inhibitors

Recent research has indicated that the abnormal expression of the deubiquitinase USP7 induces tumorigenesis via multiple cell pathways, and in particular, the p53-MDM2-USP7 pathway is well understood. USP7 is emerging as a promising target for cancer therapy. However, there are limited reports on USP7 inhibitors. Here we report design, synthesis and biological evaluation of novel quinazolin-4(3H)-one derivatives as potent USP7 inhibitors. Our results indicated that the compounds C9 and C19 exhibited the greatest potency against the USP7 catalytic domain, with IC₅₀ values of 4.86 μM and 1.537 μM, respectively. Ub-AMC assays further confirmed IC₅₀ values of 5.048 μM for C9 and 0.595 μM for C19. MTT assays indicated that gastric cancer MGC-803 cells were more sensitive to these compounds than BGC-823 cells. Flow cytometry analysis revealed that C9 restricted cancer cell growth at the G0/G1 and S phases and inhibited the proliferation and clone formation of MGC-803 cells. Further biochemical experiments indicated that C9 decreased the MDM2 protein level and increased the levels of the tumour suppressors p53 and p21 in a dose-dependent manner. Docking studies predicted that solvent exposure of the side chains of C9 and C19 would uniquely form hydrogen bonds with Met407 of USP7. Additionally, C9 exhibited a remarkable anticancer effect in a zebrafish gastric cancer MGC-803 cell model. Our results demonstrated that quinazolin-4(3H)-one derivatives were suitable as leads for the development of novel USP7 inhibitors and especially for anti-gastric cancer drugs.

DUBs Activating the Hedgehog Signaling Pathway: A Promising Therapeutic Target in Cancer

The Hedgehog (HH) pathway governs cell proliferation and patterning during embryonic development and is involved in regeneration, homeostasis and stem cell maintenance in adult tissues. The activity of this signaling is finely modulated at multiple levels and its dysregulation contributes to the onset of several human cancers. Ubiquitylation is a coordinated post-translational modification that controls a wide range of cellular functions and signaling transduction pathways. It is mediated by a sequential enzymatic network, in which ubiquitin ligases (E3) and deubiquitylase (DUBs) proteins are the main actors. The dynamic balance of the activity of these enzymes dictates the abundance and the fate of cellular proteins, thus affecting both physiological and pathological processes. Several E3 ligases regulating the stability and activity of the key components of the HH pathway have been identified. Further, DUBs have emerged as novel players in HH signaling transduction, resulting as attractive and promising drug targets. Here, we review the HH-associated DUBs, discussing the consequences of deubiquitylation on the maintenance of the HH pathway activity and its implication in tumorigenesis. We also report the recent progress in the development of selective inhibitors for the DUBs here reviewed, with potential applications for the treatment of HH-related tumors.

N-benzylpiperidinol derivatives as novel USP7 inhibitors: Structure-activity relationships and X-ray crystallographic studies

USP7 as a deubiquitinase plays important roles in regulating the stability of some oncoproteins including MDM2 and DNMT1, and thus represents a potential anticancer target. Through comparative analysis of USP7 co-crystal structures in complex with the reported piperidinol inhibitors, we noticed that the USP7 Phe409 sub-site might have good adaptability to the ligands. Based on this observation, 55 N-aromatic and N-benzyl piperidinol derivatives were designed, synthesized and biologically evaluated, among which compound L55 was identified as a highly selective and potent USP7 inhibitor (IC₅₀ = 40.8 nM, K_D = 78.3 nM). X-ray crystallographic studies revealed that L55 bound to USP7 with a new pose that was very different from the previously reported inhibitors. The results of cellular assays showed that L55 had strong antitumor activity against LNCaP (IC₅₀ = 29.6 nM) and RS4; 11 (IC₅₀ = 41.6 nM) cells, probably through inducing cell death and restricting G0/G1 and S phases. Moreover, L55 dose-dependently reduced the protein levels of MDM2 and DNMT1 and increased the protein levels of p53 and p21. These findings could have valuable implications for designing novel structural classes of USP7 inhibitors.

Discovery of Ubiquitin-Specific Protease 7 (USP7) Inhibitors with Novel Scaffold Structures by Virtual Screening, Molecular Dynamics Simulation, and Biological Evaluation

USP7 has been regarded as a potential therapeutic target for cancer. In this study, virtual screening, molecular dynamics (MD) simulation, and biological evaluation have been applied for the discovery of novel USP7 inhibitors targeting the catalytic active site. Among the obtained compounds, compound 12 with a novel scaffold structure exhibited certain USP7 inhibitory activity (Ub-AMC assay IC₅₀ = 18.40 ± 1.75 μM, Ub-Rho assay IC₅₀ = 7.75 μM). The binding affinity between USP7_CD (USP7 catalytic domain) and this hit compound was confirmed with a K_D value of 4.46 ± 0.86 μM. Preliminary in vitro studies disclosed its antiproliferative activity on human prostate cancer cell line LNCaP with an IC₅₀ value of 15.43 ± 3.49 μM. MD simulation revealed the detailed differences of protein-ligand interactions between USP7_CD and the ligands, including the reference compound ALM4 and compound 12, providing some important information for improving the bioactivity of 12. This hit compound will serve as a promising starting point for facilitating the further discovery of novel USP7 inhibitors.

Targeting USP7-Mediated Deubiquitination of MDM2/MDMX-p53 Pathway for Cancer Therapy: Are We There Yet?

The p53 tumor suppressor protein and its major negative regulators MDM2 and MDMX oncoproteins form the MDM2/MDMX-p53 circuitry, which plays critical roles in regulating cancer cell growth, proliferation, cell cycle progression, apoptosis, senescence, angiogenesis, and immune response. Recent studies have shown that the stabilities of p53, MDM2, and MDMX are tightly controlled by the ubiquitin-proteasome system. Ubiquitin specific protease 7 (USP7), one of the most studied deubiquitinating enzymes plays a crucial role in protecting MDM2 and MDMX from ubiquitination-mediated proteasomal degradation. USP7 is overexpressed in human cancers and contributes to cancer initiation and progression. USP7 inhibition promotes the degradation of MDM2 and MDMX, activates the p53 signaling, and causes cell cycle arrest and apoptosis, making USP7 a potential target for cancer therapy. Several small-molecule inhibitors of USP7 have been developed and shown promising efficacy in preclinical settings. In the present review, we focus on recent advances in the understanding of the USP7-MDM2/MDMX-p53 network in human cancers as well as the discovery and development of USP7 inhibitors for cancer therapy.

Deubiquitinases: Pro-oncogenic Activity and Therapeutic Targeting in Blood Malignancies

Deubiquitinases are enzymes that remove ubiquitin moieties from the vast majority of cellular proteins, controlling their stability, interactions, and localization. The expression and activity of deubiquitinases are critical for physiology and can go awry in various diseases, including cancer. Based on recent findings in human blood cancers, we discuss the functions of selected deubiquitinases in acute leukemia and efforts to target these enzymes with the aim of blocking leukemia growth and improving disease outcomes. We focus on the emergence of the newest generation of preclinical inhibitors by discussing their modes of inhibition and their effects on leukemia biology.

Organocatalyzed Domino Synthesis of New Thiazole-Based Decahydroacridine-1,8-diones and Dihydropyrido[2,3-d : 6,5-d']- dipyrimidines in Water as Antimicrobial Agents

Organopromoter, 2-aminoethanesulfonic acid was used to catalyze the synthesis of a series of structurally intriguing new hybrids thiazolyl acridine-1,8(2H,5H)-diones and dihydropyrido[2,3-d : 6,5-d']dipyrimidine-2,4,6,8(1H,3H,5H,7H)-tetraones for the first time. 2-Aminoethanesulfonic acid is a biobased organopromoter, used to generate four new bonds for the synthesis of new coupled thiazole-based decahydroacridine-1,8-diones. Superior green credentials, operational simplicity, easy work-up and recyclability of the catalyst are the key strengths of this method. The broad substrate scope, mild reaction conditions, short reaction time, cost effectiveness, high atom economy and good to excellent yields make the present method a distinct improvement over existing methods. Spectral (IR, ¹ H-NMR,¹³ C-NMR, Mass) data and elemental analyses confirmed the structures of the titled products. A series of thiazolyl acridine-1,8(2H,5H)-diones and dihydropyrido[2,3-d : 6,5-d']dipyrimidine-2,4,6,8(1H,3H,5H,7H)-tetraones were screened for their antimicrobial activity against four bacterial and three fungal strains.

Recent advances in the development of ubiquitin-specific-processing protease 7 (USP7) inhibitors

Ubiquitin-specific-processing protease 7 (USP7) is one among the several deubiquitinating enzymes gaining central attention in the current cancer research. Most recent studies have focused on illustrating how USP7 is involved in the cancer process, while few articles reported the development of small molecule USP7 inhibitors. Although some review articles dealt with USP7, they mainly focused on its physiological role and not on the development of USP7 inhibitors. In this review, we systematically summarise the structures, activities and structure-activity relationship (SAR) of small molecule USP7 inhibitors, recently disclosed in scientific articles and patents from 2000 to 2019. The binding modes of typical compounds and their interactions with USP7 are also presented, while other deubiquitinase inhibitors are described in detail. Meanwhile, we briefly introduce the biochemical and physiological functions of USP7. Finally, challenges and potential strategies in developing small molecule USP7 inhibitors are also discussed.

Thiazole-containing compounds as therapeutic targets for cancer therapy

In the last few decades, considerable progress has been made in anticancer agents development, and several new anticancer agents of natural and synthetic origin have been produced. Among heterocyclic compounds, thiazole, a 5-membered unique heterocyclic motif containing sulphur and nitrogen atoms, serves as an essential core scaffold in several medicinally important compounds. Thiazole nucleus is a fundamental part of some clinically applied anticancer drugs, such as dasatinib, dabrafenib, ixabepilone, patellamide A, and epothilone. Recently, thiazole-containing compounds have been successfully developed as possible inhibitors of several biological targets, including enzyme-linked receptor(s) located on the cell membrane, (i.e., polymerase inhibitors) and the cell cycle (i.e., microtubular inhibitors). Moreover, these compounds have been proven to exhibit high effectiveness, potent anticancer activity, and less toxicity. This review presents current research on thiazoles and elucidates their biological importance in anticancer drug discovery. The findings may aid researchers in the rational design of more potent and bio-target specific anticancer drug molecules.

Thiazole in the targeted anticancer drug discovery

Cancer is known as one of the main causes of death in the world; and many compounds have been synthesized to date with potential use in cancer therapy. Thiazole is a versatile heterocycle, found in the structure of many drugs in use as well as anticancer agents. This review provides an overview of recent advances in thiazole-bearing compounds as anticancer agents with particular emphasis on their mechanism of action in cancerous cells. Chemical designs, structure–activity relationships and relevant preclinical properties have been comprehensively described.

p53 modifications: exquisite decorations of the powerful guardian

The last 40 years have witnessed how p53 rose from a viral binding protein to a central factor in both stress responses and tumor suppression. The exquisite regulation of p53 functions is of vital importance for cell fate decisions. Among the multiple layers of mechanisms controlling p53 function, posttranslational modifications (PTMs) represent an efficient and precise way. Major p53 PTMs include phosphorylation, ubiquitination, acetylation, and methylation. Meanwhile, other PTMs like sumoylation, neddylation, O-GlcNAcylation, adenosine diphosphate (ADP)-ribosylation, hydroxylation, and β-hydroxybutyrylation are also shown to play various roles in p53 regulation. By independent action or interaction, PTMs affect p53 stability, conformation, localization, and binding partners. Deregulation of the PTM-related pathway is among the major causes of p53-associated developmental disorders or diseases, especially in cancers. This review focuses on the roles of different p53 modification types and shows how these modifications are orchestrated to produce various outcomes by modulating p53 activities or targeted to treat different diseases caused by p53 dysregulation.

Role of sulphur-heterocycles in medicinal chemistry: An update

From many decades, S-heterocycles have maintained their status as an important part and core of FDA approved drugs and medicinally active compounds. With exhaustive exploration of nitrogen heterocycles in medicinal chemistry, researchers have shifted their interest towards other heterocycles, especially, S-heterocycles. Thus several attempts have been made to synthesize a variety of new sulphur containing compounds with high medicinal value and low toxicity profile, in comparison to previous N-heterocycles. Till today, S-heterocycle containing compounds have been largely reported as anticancer, antidiabetic, antimicrobial, antihypertension, antivral, antinflammatory etc. In this review, the authors have tried to provide a critical analysis of synthesis and medicinal attributes of sulphur containing heterocycles such as thiirane, thiophene, thiazole, thiopyran, thiazolidine etc reported within last five years to emphasize the significance and usefulness of these S-heterocycles in the drug discovery process.

Modulating protein-protein interaction networks in protein homeostasis

Protein-protein interactions (PPIs) occur in complex networks. These networks are highly dependent on cellular context and can be extensively altered in disease states such as cancer and viral infection. In recent years, there has been significant progress in developing inhibitors that target individual PPIs either orthosterically (at the interface) or allosterically. These molecules can now be used as tools to dissect PPI networks. Here, we review recent examples that highlight the use of small molecules and engineered proteins to probe PPIs within the complex networks that regulate protein homeostasis. Researchers have discovered multiple mechanisms to modulate PPIs involved in host/viral interactions, deubiquitinases, the ATPase p97/VCP, and HSP70 chaperones. However, few studies have evaluated the effect of such modulators on the target's network or have compared the biological implications of different modulation strategies. Such studies will have an important impact on next generation therapeutics.

The m6A demethylase FTO promotes the growth of lung cancer cells by regulating the m6A level of USP7 mRNA

Lung cancer is one of the leading causes of cancer-related death in developed countries. Despite decades of intensive efforts to comate this malignant disease, the prognosis of lung cancer remains unfavorable and is especially poor in advanced non-small cell lung cancer (NSCLC). However, whether and how the m6A demethylase FTO functions in lung cancer cells remain unknown. Here in the present study, we show that FTO plays an oncogenic role in human NSCLC. FTO mRNA and protein levels were overexpressed in human NSCLC tissues and cell lines, which was associated with the reduced m6A content. We next knocked down FTO expression in human lung cancer cell lines with lentivirus-mediated shRNAs and the cellular proliferation assay demonstrated that FTO loss-of-function reduced the proliferation rate of cancer cells. FTO knockdown also inhibited the colony formation ability of lung cancer cells. Importantly, our xenograft experiment showed that FTO knockdown reduced lung cancer cells growth in vivo. Mechanism analysis demonstrated that FTO decreased the m6A level and increased mRNA stability of ubiquitin-specific protease (USP7), which was relied on the demethylase activity of FTO. USP7 mRNA level was overexpressed in human lung cancer tissues and USP7 expression was positively correlated with FTO mRNA level. Genetic knockdown or pharmacological inhibition (P5091 or P22027) of USP7 reduced the proliferation rate of lung cancer cells and decreased the capacity of colony formation of lung cancer cells in vitro, whereas lung cancer cells growth inhibition by FTO knockdown is restored by overexertion of USP7. Collectively, our findings demonstrate that the m6A demethylase FTO promotes the growth of NSCLC cells by increasing the expression of USP7.

Nuclear deubiquitination in the spotlight: the multifaceted nature of USP7 biology in disease

Ubiquitination is a versatile and tightly regulated post-translational protein modification with many distinct outcomes affecting protein stability, localization, interactions, and activity. Ubiquitin chain linkages anchored on substrates can be further modified by additional post-translational modifications, including phosphorylation and SUMOylation. Deubiquitinases (DUBs) reverse these ubiquitin marks with matched levels of precision. Over hundred known DUBs regulate a wide variety of cellular events. In this review, we focus on ubiquitin-specific protease 7 (USP7, also known as herpesvirus-associated ubiquitin-specific protease, or HAUSP) as one of the best studied, disease-associated DUBs. By highlighting the functions of USP7, particularly in the nucleus, and the emergence of the newest generation of USP7 inhibitors, we illustrate the importance of individual DUBs in the nucleus, and the therapeutic prospects of DUB targeting in human disease.

Crystal structures of 6a,6b,7,11a-tetra-hydro-6H,9H-spiro-[chromeno[3',4':3,4]pyrrolo-[1,2-c]thia-zole-11,3'-indoline]-2',6-dione and 5'-methyl-6a,6b,7,11a-tetra-hydro-6H,9H-spiro-[chromeno[3',4':3,4]pyrrolo-[1,2-c]thia-zole-11,3'-indoline]-2',6-dione

The title compounds, C20H16N2O3S, (I), and C21H18N2O3S, (II), differ by the presence of a methyl group in position 5 on the 1H-indole-2-one ring of compound (II). The two compounds have a structural overlap r.m.s. deviation of 0.48 Å. There is a significant difference in the conformation of the thia-zolidine ring: it has a twisted conformation on the fused N-C bond in (I), but an envelope conformation in compound (II) with the S atom as the flap. The planar pyrrolidine ring of the indole ring system is normal to the mean plane of the five-membered pyrrolidine ring of the pyrrolo-thia-zole unit in both compounds, with dihedral angles of 88.71 (9) and 84.59 (8)°. The pyran rings in both structures have envelope conformations with the methyl-ene C atom adjacent to the C=O group as the flap. In both compounds, there is a short intra-molecular C-H⋯O contact present. In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds forming chains propagating along the b-axis direction. The chains are linked by N-H⋯π inter-actions, forming layers parallel to (10). In the crystal of (II), mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers which are linked by C-H⋯O hydrogen bonds to form a three-dimensional structure.

Targeting ubiquitin specific protease 7 in cancer: A deubiquitinase with great prospects

Deubiquitinase (DUB)-mediated cleavage of ubiquitin chain balances ubiquitination and deubiquitination for determining protein fate. USP7 is one of the best characterized DUBs and functionally important. Numerous proteins have been identified as potential substrates and binding partners of USP7; those play crucial roles in diverse array of cellular and biological processes including tumour suppression, cell cycle, DNA repair, chromatin remodelling, and epigenetic regulation. This review aims at summarizing the current knowledge of this wide association of USP7 with many cellular processes that enlightens the possibility of abnormal USP7 activity in promoting oncogenesis and the importance of identification of specific inhibitors.

Targeting HAUSP in both p53 wildtype and p53-mutant tumors

Inhibition of Mdm2 function is a validated approach to restore p53 activity for cancer therapy; nevertheless, inhibitors of Mdm2 such as Nutlin-3 have certain limitations, suggesting that additional targets in this pathway need to be further elucidated. Our finding that the Herpesvirus-Associated Ubiquitin-Specific Protease (HAUSP, also called USP7) interacts with the p53/Mdm2 protein complex, was one of the first examples that deubiquitinases (DUBs) exhibit a specific role in regulating protein stability. Here, we show that inhibitors of HAUSP and Nutlin-3 can synergistically activate p53 function and induce p53-dependent apoptosis in human cancer cells. Notably, HAUSP can also target the N-Myc oncoprotein in a p53-independent manner. Moreover, newly synthesized HAUSP inhibitors are more potent than the commercially available inhibitors to suppress N-Myc activities in p53 mutant cells for growth suppression. Taken together, our study demonstrates the utility of HAUSP inhibitors to target cancers in both a p53-depdentent and -independent manner.

Discovery and characterization of highly potent and selective allosteric USP7 inhibitors

Given the importance of ubiquitin-specific protease 7 (USP7) in oncogenic pathways, identification of USP7 inhibitors has attracted considerable interest. Despite substantial efforts, however, the development of validated deubiquitinase (DUB) inhibitors that exhibit drug-like properties and a well-defined mechanism of action has proven particularly challenging. In this article, we describe the identification, optimization and detailed characterization of highly potent (IC₅₀ < 10 nM), selective USP7 inhibitors together with their less active, enantiomeric counterparts. We also disclose, for the first time, co-crystal structures of a human DUB enzyme complexed with small-molecule inhibitors, which reveal a previously undisclosed allosteric binding site. Finally, we report the identification of cancer cell lines hypersensitive to USP7 inhibition (EC₅₀ < 30 nM) and demonstrate equal or superior activity in these cell models compared to clinically relevant MDM2 antagonists. Overall, these findings demonstrate the tractability and druggability of DUBs, and provide important tools for additional target validation studies.

Structure-Guided Development of a Potent and Selective Non-covalent Active-Site Inhibitor of USP7

Deubiquitinating enzymes (DUBs) have garnered significant attention as drug targets in the last 5-10 years. The excitement stems in large part from the powerful ability of DUB inhibitors to promote degradation of oncogenic proteins, especially proteins that are challenging to directly target but which are stabilized by DUB family members. Highly optimized and well-characterized DUB inhibitors have thus become highly sought after tools. Most reported DUB inhibitors, however, are polypharmacological agents possessing weak (micromolar) potency toward their primary target, limiting their utility in target validation and mechanism studies. Due to a lack of high-resolution DUB⋅small-molecule ligand complex structures, no structure-guided optimization efforts have been reported for a mammalian DUB. Here, we report a small-molecule⋅ubiquitin-specific protease (USP) family DUB co-structure and rapid design of potent and selective inhibitors of USP7 guided by the structure. Interestingly, the compounds are non-covalent active-site inhibitors.

3-(4-Methoxyphenyl)-4-methyl-N-[4-(4-methylphenyl)-1,3-thiazol-2-yl]benzamide

In the title compound, C25H22N2O2S, the methylphenyl rings are oriented with a dihedral angle of 19.4 (1)° with respect to each other. In the crystal, molecules are linkedviastrong N—H...O hydrogen bonds, which formC(11) chains propagating along [001]. In addition, weak C—H...O and C—H...π interactions are observed in the structure.