Recent Advances in Glyoxalase-I Inhibition

Computational fragment-based drug design of potential Glo-I inhibitors

In this study, a fragment-based drug design approach, particularly de novo drug design, was implemented utilising three different crystal structures in order to discover new privileged scaffolds against glyoxalase-I enzyme as anticancer agents. The fragments were evoluted to indicate potential inhibitors with high receptor affinities. The resulting compounds were served as a benchmark for choosing similar compounds from the ASINEX® database by applying different computational ligand-based drug design techniques. Afterwards, the selection of potential hits was further aided by various structure-based approaches. Then, 14 compounds were purchased, and tested in vitro against Glo-I enzyme. Of the tested 14 hits, the biological screening results showed humble activities where the percentage of Glo-I inhibition ranged from 0-18.70 %. Compound 19 and compound 28, whose percentage of inhibitions are 18.70 and 15.80%, respectively, can be considered as hits that need further optimisation in order to be converted into lead-like compounds.

Development of pathway-oriented screening to identify compounds to control 2-methylglyoxal metabolism in tumor cells

Controlling tumor-specific alterations in metabolic pathways is a useful strategy for treating tumors. The glyoxalase pathway, which metabolizes the toxic electrophile 2-methylglyoxal (MG), is thought to contribute to tumor pathology. We developed a live cell-based high-throughput screening system that monitors the metabolism of MG to generate D-lactate by glyoxalase I and II (GLO1 and GLO2). It utilizes an extracellular coupled assay that uses D-lactate to generate NAD(P)H, which is detected by a selective fluorogenic probe designed to respond exclusively to extracellular NAD(P)H. This metabolic pathway-oriented screening is able to identify compounds that control MG metabolism in live cells, and we have discovered compounds that can directly or indirectly inhibit glyoxalase activities in small cell lung carcinoma cells.

Identification of HAGHL as a novel metabolic oncogene regulating human colorectal cancer progression

PURPOSE

Cancer development remains the most challenging obstacle in colorectal cancer (CRC) treatment. The current study aims to identify and demonstrate novel oncogenes for CRC.

METHODS

The CRC data of the Cancer Genome Atlas database and the Gene Expression Omnibus database were subjected to bioinformatics analysis to identify the novel potential diagnostic and prognostic biomarkers for CRC. Immunohistochemical assay, western blot, and quantitative PCR (qPCR) were used to analyze hydroxyacylglutathione hydrolase-like (HAGHL) gene expression in CRC tissues and cultured CRC cells. D-Lactate colorimetric assay was applied to determine concentration of D-lactate in supernatants from CRC tissues and cell culture medium. Cell counting kit-8 (CCK-8) assay, flow cytometry, tumor xenografts experiment, and TUNEL staining analysis were performed to evaluate the function of HAGHL in CRC.

RESULTS

We comprehensively analyzed the CRC data of the Cancer Genome Atlas database and the Gene Expression Omnibus database, and identified several novel potential diagnostic and prognostic biomarkers for CRC, including HAGHL, DNTTIP1, DHX34, and AP1S3. The expression of HAGHL, the strongest oncogenic activity gene, is positively related to D-lactate levels in CRC tissues and negatively associated with patient prognosis. HAGHL downregulation suppressed the production of D-lactate and induced apoptosis, resulting in inhibition of cell proliferation in vitro. In vivo experiment showed that knockdown of HAGHL induced cell apoptosis and inhibited tumor growth.

CONCLUSION

These findings suggest that HAGHL acts as a novel metabolic oncogene and demonstrate the underlying mechanism by which HAGHL regulates CRC progression, highlighting its utility as a diagnostic and prognostic factor and as a potential therapeutic target for the treatment of CRC.

Design, Synthesis and Biological Evaluation of 1,4-Benzenesulfonamide Derivatives as Glyoxalase I Inhibitors

Background

Glyoxalase system is one of the defense cellular mechanisms that protect cells against endogenous harmful metabolites, mainly methylglyoxal (MG), through conversion of cytotoxic methylglyoxal into the non-toxic lactic acid. Glyoxalase system comprises of two enzymes glyoxalase I, glyoxalase II, and a catalytic amount of reduced glutathione. Cancerous cells overexpress glyoxalase I, making it a target for cancer therapy. Many studies have been conducted to identify potent Glx-I inhibitors.

Methods

Aiming to discover and develop novel Glx-I inhibitors, a series of 1,4-benzenesulfonamide derivatives were designed, synthesized, and biologically evaluated in vitro against human Glx-I enzyme. Seventeen compounds were designed based on the hit compound that was obtained from searching the National Cancer Institute (NCI) database. The synthesis of the target compounds (13-29) was accomplished utilizing an azo coupling reaction of aniline derivatives and activated substituted aromatic compounds. To understand the binding mode of the active compounds at the active site of Glx-I, docking studies were performed.

Results

Structure activity relationship (SAR) studies were accomplished which led to the identification of several compounds that showed potent inhibitory activity with IC50 values below 10 μM. Among the compounds tested, compounds (E)-2-hydroxy-5-((4-sulfamoylphenyl)diazenyl)benzoic acid (26) and (E)-4-((8-hydroxyquinolin-5-yl)diazenyl) benzenesulfonamide (28) displayed potent Glx-I inhibitory activity with IC50 values of 0.39 μM and 1.36 µM, respectively. Docking studies of compounds 26 and 28 were carried out to illustrate the binding mode of the molecules into the Glx-I active site.

Conclusion

Our results show that compounds 26 and 28 displayed potent Glx-I inhibitory activity and can bind the Glx-I well. These findings should lead us to discover new classes of compounds with better Glx-I inhibition.

Crystal structure and biochemical analysis of the specialized deoxynivalenol-detoxifying glyoxalase SPG from Gossypium hirsutum

Deoxynivalenol (DON) and its acetylated derivatives such as 3-acetyldeoxynivalenol (3A-DON) and 15-acetyldeoxynivalenol (15A-DON) are notorious mycotoxins in Fusarium contaminated cereals, which pose a great threat to human and livestock health. The specialized glyoxalase I from Gossypium hirsutum (SPG) can lower the toxicity of 3A-DON by conducting isomerization to transfer C8 carbonyl to C7 and double bond from C9-C10 to C8-C9. Here we report that the substrate-flexible SPG can also recognize 15A-DON and DON, probably following the same isomerization mechanism as that for 3A-DON. The crystallographic, mutagenesis, and biochemical analyses revealed that SPG provides a hydrophobic pocket to accommodate the substrate and residue E167 might serve as the catalytic base. A variant SPGY62A that was constructed based on structure-based protein engineering exhibited elevated catalytic activity towards DON, 3A-DON, and 15A-DON by >70%. Furthermore, variant SPGY62A was successfully expressed in Pichia pastoris, whose catalytic activity was also compared to that produced in Escherichia coli. These results provide a blueprint for further protein engineering of SPG and reveal the potential applications of the enzyme in detoxifying DON, 3A-DON and 15A-DON.

Protein Lactylation Critically Regulates Energy Metabolism in the Protozoan Parasite Trypanosoma brucei

Lysine lactylation has been recognized as a novel post-translational modification occurring on histones. However, lactylation in non-histone proteins, especially in proteins of early branching organisms, is not well understood. Energy metabolism and the histone repertoire in the early diverging protozoan parasite Trypanosoma brucei, the causative agent of African trypanosomiasis, markedly diverge from those of conventional eukaryotes. Here, we present the first exhaustive proteome-wide investigation of lactylated sites in T. brucei. We identified 387 lysine-lactylated sites in 257 proteins of various cellular localizations and biological functions. Further, we revealed that glucose metabolism critically regulates protein lactylation in T. brucei although the parasite lacks lactate dehydrogenase. However, unlike mammals, increasing the glucose concentration reduced the level of lactate, and protein lactylation decreased in T. brucei via a unique lactate production pathway. In addition to providing a valuable resource, these foregoing data reveal the regulatory roles of protein lactylation of trypanosomes in energy metabolism and gene expression.

Maternal malnutrition and anaemia in India: dysregulations leading to the 'thin-fat' phenotype in newborns

Maternal and child malnutrition and anaemia remain the leading factors for health loss in India. Low birth weight (LBW) offspring of women suffering from chronic malnutrition and anaemia often exhibit insulin resistance and infantile stunting and wasting, together with increased risk of developing cardiometabolic disorders in adulthood. The resulting self-perpetuating and highly multifactorial disease burden cannot be remedied through uniform dietary recommendations alone. To inform approaches likely to alleviate this disease burden, we implemented a systems-analytical approach that had already proven its efficacy in multiple published studies. We utilised previously published qualitative and quantitative analytical results of rural and urban field studies addressing maternal and infantile metabolic and nutritional parameters to precisely define the range of pathological phenotypes encountered and their individual biological characteristics. These characteristics were then integrated, via extensive literature searches, into metabolic and physiological mechanisms to identify the maternal and foetal metabolic dysregulations most likely to underpin the 'thin-fat' phenotype in LBW infants and its associated pathological consequences. Our analyses reveal hitherto poorly understood maternal nutrition-dependent mechanisms most likely to promote and sustain the self-perpetuating high disease burden, especially in the Indian population. This work suggests that it most probably is the metabolic consequence of 'ill-nutrition' - the recent and rapid dietary shifts to high salt, high saturated fats and high sugar but low micronutrient diets - over an adaptation to 'thrifty metabolism' which must be addressed in interventions aiming to significantly alleviate the leading risk factors for health deterioration in India.

Identification of the first "two digit nano-molar" inhibitors of the human glyoxalase-I enzyme as potential anticancer agents

BACKGROUND

Glyoxalase-I (Glo-I) enzyme is recognized as an indispensable druggable target in cancer treatment. Its inhibition will lead to the accumulation of toxic aldehyde metabolites and cell death. Paramount efforts were spent to discover potential competitive inhibitors to eradicate cancer.

OBJECTIVE

Based on our previously work on this target for discovering potent inhibitors of this enzyme, herein, we address the discovery of the most potent Glo-I inhibitors reported in literature with two digits nano-molar activity.

METHODS

Molecular docking and in vitro assay were performed to discover these inhibitors and explore the active site's binding pattern. A detailed SAR scheme was generated, which identifies the significant functionalities responsible for the observed activity.

RESULTS

Compound 1 with an IC50 of 16.5 nM exhibited the highest activity, catechol moiety as an essential zinc chelating functionality. It has been shown by using molecular modeling techniques that the catechol moiety is responsible for the chelation zinc atom at the active site, an essential feature for enzyme inhibition.

CONCLUSION

Catechol derivatives are successful zinc chelators in the Glo-I enzyme while showing exceptional activity against the enzyme to the nanomolar level.

Ellagic acid: A potent glyoxalase-I inhibitor with a unique scaffold

The glyoxalase system, particularly glyoxalase-I (GLO-I), has been approved as a potential target for cancer treatment. In this study, a set of structurally diverse polyphenolic natural compounds were investigated as potential GLO-I inhibitors. Ellagic acid was found, computationally and experimentally, to be the most potent GLO-I inhibitor among the tested compounds which showed an IC50 of 0.71 mmol L-1. Its binding to the GLO-I active site seemed to be mainly driven by ionic interaction via its ionized hydroxyl groups with the central Zn ion and Lys156, along with other numerous hydrogen bonding and hydrophobic interactions. Due to its unique and rigid skeleton, it can be utilized to search for other novel and potent GLO-I inhibitors via computational approaches such as pharmacophore modeling and similarity search methods. Moreover, an inspection of the docked poses of the tested compounds showed that chlorogenic acid and dihydrocaffeic acid could be considered as lead compounds worthy of further optimization.

Design, synthesis and biological evaluation of novel glyoxalase I inhibitors possessing diazenylbenzenesulfonamide moiety as potential anticancer agents

The enzyme glyoxalase-I (Glo-I) is an essential therapeutic target in cancer treatment. Significant efforts have been made to discover competitive inhibitors of Glo-I as potential anticancer agents. Herein, we report the synthesis of a series of diazenylbenzenesulfonamide derivatives, their in vitro evaluation against Glo-I and the resulting structure-activity relationships. Among the compounds tested, compounds 9h and 9j exhibited the highest activity with IC50 1.28 µM and 1.13 µM, respectively. Docking studies to explore the binding mode of the compounds identified key moieties that may contribute to the observed activities. The active compounds will serve as suitable leads for further chemical optimization.

Recent advances in the discovery and development of glyoxalase I inhibitors

Glyoxalase I (GLO1) is a homodimeric Zn²⁺-metalloenzyme that catalyses the transformation of methylglyoxal (MG) to d-lacate through the intermediate S-d-lactoylglutathione. Growing evidence indicates that GLO1 has been identified as a potential target for the treatment cancer and other diseases. Various inhibitors of GLO1 have been discovered or developed over the past several decades including natural or natural product-based inhibitors, GSH-based inhibitors, non-GSH-based inhibitors, etc. The aim of this review is to summarize recent achievements of concerning discovery, design strategies, as well as pharmacological aspects of GLO1 inhibitors with the target of promoting their development toward clinical application.

Methylglyoxal Acts as a Tumor-Promoting Factor in Anaplastic Thyroid Cancer

Methylglyoxal (MG) is a potent inducer of advanced glycation end products (AGEs). MG, long considered a highly cytotoxic molecule with potential anticancer value, is now being re-evaluated to a protumorigenic agent in some malignancies. Anaplastic thyroid cancer (ATC) is an extremely aggressive and highly lethal cancer for which conventional therapies have proved ineffective. Successful therapeutic intervention in ATC is undermined by our poor understanding of its molecular etiology. In the attempt to understand the role of MG in ATC aggressiveness, we used immunohistochemistry to examine the level of MG protein adducts in ATC and slow-growing papillary thyroid cancer (PTC). We detected a high level of MG adducts in ATC compared to PTC ones, suggesting a protumor role for MG-mediated dicarbonyl stress in ATC. Accordingly, MG adduct accumulation in ATC cells in vitro was associated with a marked mesenchymal phenotype and increased migration/invasion, which were both reversed by aminoguanidine (AG)—a scavenger of MG—and resveratrol—an activator of Glyoxalase 1 (Glo1), the key metabolizing enzyme of MG. Our study represents the first demonstration that MG, via AGEs, acts as a tumor-promoting factor in ATC and suggests that MG scavengers and/or Glo1 activators merit investigations as potential therapeutic strategies for this malignancy.

Metal-Binding Pharmacophore Library Yields the Discovery of a Glyoxalase 1 Inhibitor

Anxiety and depression are common, highly comorbid psychiatric diseases that account for a large proportion of worldwide medical disability. Glyoxalase 1 (GLO1) has been identified as a possible target for the treatment of anxiety and depression. GLO1 is a Zn²⁺-dependent enzyme that isomerizes a hemithioacetal, formed from glutathione and methylglyoxal, to a lactic acid thioester. To develop active inhibitors of GLO1, fragment-based drug discovery was used to identify fragments that could serve as core scaffolds for lead development. After screening a focused library of metal-binding pharmacophores, 8-(methylsulfonylamino)quinoline (8-MSQ) was identified as a hit. Through computational modeling and synthetic elaboration, a potent GLO1 inhibitor was developed with a novel sulfonamide core pharmacophore. A lead compound was demonstrated to penetrate the blood-brain barrier, elevate levels of methylglyoxal in the brain, and reduce depression-like behavior in mice. These findings provide the basis for GLO1 inhibitors to treat depression and related psychiatric illnesses.