Glyoxalase 1 as a Therapeutic Target in Cancer and Cancer Stem Cells

Metolazone and Azosemide, Clinically Utilized Diuretics, Exhibit Inhibitory Activity for Glyoxalase I

Methylglyoxal (MGO), a byproduct produced in the process of glycolysis, has cytotoxicity and forms advanced glycation endproducts (AGEs), which cause cell failure in several tissues. Because MGO is mainly removed by the action of glyoxalase I (GLO1), the activity of this enzyme contributes to the accumulation of MGO. We recently found that quinetazone, a diuretic pharmaceutical agent, has the potential to inhibit GLO1 activity. Therefore, we explored whether diuretics that have a similar structure to quinetazone inhibit GLO1. The inhibitory characteristics of diuretics with recombinant GLO1 were spectrophotometrically determined. Cell proliferation and accumulation of MGO-derived AGEs were evaluated by MTT assay and Western blotting. Among the thiazide, thiazide-like, and loop diuretics, metolazone and azosemide were found to inhibit GLO1 activity by 97% at 100 µM. Furthermore, we examined whether the substructures of these diuretics have inhibitory activity, quinazolinone or phenyltetrazole were determined to be the minimal structures of metolazone or azosemide required for inhibition of GLO1, respectively. In proximal renal tubule-like HK-2 and vascular endothelial cell-like EA.hy926 cells, these diuretics were shown to inhibit cell proliferation and induce accumulation of MGO-derived AGEs. In contrast, the substructures of these diuretics that did not affect GLO1 activity did not cause these changes. Metolazone and azosemide have inhibitory effects against GLO1. Considering that these diuretics are clinically employed as pharmaceutical agents, high or prolonged dosages may contribute to pathogenesis through GLO1 inhibition, followed by MGO and/or AGE accumulation.

Methylglyoxal mutagenizes single-stranded DNA via Rev1-associated slippage and mispairing

Methylglyoxal (MG) is a highly reactive aldehyde that is produced endogenously during metabolism and is derived from exogenous sources such as sugary food items and cigarette smoke. Unless detoxified by glyoxalases (Glo1 and Glo2), MG can readily react with all major biomolecules, including DNA and proteins, generating characteristic lesions and glycation-derived by- products. As a result, MG exposure has been linked to a variety of human diseases, including cancers. Prior studies show that MG can glycate DNA, preferentially on guanine residues, and cause DNA damage. However, the mutagenicity of MG is poorly understood in vivo. In the context of cancer, it is essential to comprehend the true contribution of MG to genome instability and global mutational burden. In the present study, we show that MG can robustly mutagenize induced single-stranded DNA (ssDNA) in yeast, within a guanine centered mutable motif. We demonstrate that genome-wide MG mutagenesis in ssDNA is greatly elevated throughout the genome in the absence of Glo1, and abrogated in the presence of the aldehyde quencher aminoguanidine. We uncovered strand slippage and mispairing as the predominant mechanism for generation of all MG-associated mutations, and demonstrate that the translesion polymerase Rev1 is necessary in this pathway. Finally, we find that the primary MG-associated mutation is enriched in a variety of sequenced tumor datasets. We discuss the genomic impact of methylglyoxal exposure in the context of mutagenesis, DNA damage, and carcinogenesis.

Protein lactylation in cancer: mechanisms and potential therapeutic implications

Increased glycolysis, which leads to high lactate production, is a common feature of cancer cells. Recent evidence suggests that lactate plays a role in the post-translational modification of histone and nonhistone proteins via lactylation. In contrast to genetic mutations, lactylation in cancer cells is reversible. Thus, reversing lactylation can be exploited as a pharmacological intervention for various cancers. Here we discuss recent advances in histone and nonhistone lactylation in cancer, including L-, D- and S-lactylation, as well as alanyl-tRNA synthetase as a novel lactyltransferase. We also discuss potential approaches for targeting lactylation as a therapeutic opportunity in cancer treatment.

Simplified and economic measurement of glyoxalase I activity using 2,4-dinitrophenylhydrazine: A valuable tool for researchers

Glyoxalase I (Glo I) is an enzyme essential for detoxifying methylglyoxal, a toxic compound associated with advanced glycation end products. Given Glo I's multifaceted roles in various physiological and pathological processes, accurately measuring its activity is crucial for understanding its implications in metabolic disorders. The current assay utilizes 2,4-dinitrophenylhydrazine (2,4-DNPH) to measure Glo I activity. This reagent has previously been employed to evaluate a group of enzyme protocols. The procedure involves incubating Glo I enzyme samples in a controlled phosphate buffer at pH 6.6, optimizing conditions for enzymatic activity. Glutathione and methylglyoxal serve as substrates, with Glo I catalyzing the conversion of the hemithioacetal adduct into S-D-lactoylglutathione. Unreacted methylglyoxal is quantified by forming a colored hydrazone complex with 2,4-DNPH. The 2,4-DNPH method is rigorously validated for linearity, stability, resistance to interference, and sensitivity from several chemicals. It strongly correlates with the existing ultraviolet method, offering enhanced simplicity and cost-effectiveness. The protocol allows precise quantification of Glo I activity, with potential in research and diagnostics. Intra- and inter-day analyses confirm accuracy as percentage relative error, ensuring reliable measurement activity. The DNPH-Glo I method exhibited excellent sensitivity, with low limits of detection and quantification at 0.006 U/L and 0.018 U/L, respectively. This research provides valuable insights into the quantification of Glo I, highlighting significant implications for future studies in metabolic disorders and related health fields. This study contributes to a deeper understanding of its role in health and disease management by advancing the methods available for measuring Glo I activity.

Demonstration of Enhancement of Tumor Intravasation by Dicarbonyl Stress Using a Microfluidic Organ-on-chip

Cancer metastasis involves cell migration from their primary organ foci into vascular channels, followed by dissemination to prospective colonization sites. Vascular entry of tumor cells or intravasation involves their breaching stromal and endothelial extracellular matrix (ECM) and the endothelial barriers. How the kinetics of this breach are confounded by chronic inflammatory stresses seen in diabetes and aging remains ill-investigated. To study the problem, a histopathology-motivated, imaging-tractable, microfluidic multi-organ-on-chip platform is constructed, that seamlessly integrates a breast tumor-like compartment: invasive MDA-MB-231 in a 3D Collagen I scaffold, and a flow-implemented vascular channel: immortalized human aortic endothelia (TeloHAEC) on laminin-rich basement membrane (lrBM). The chip showcases the complexity of intravasation, wherein tumor cells and endothelia cooperate to form anastomotic structures, which facilitate cancer cell migration into the vascular channel. Upon entry, cancer cells adhere to and flow within the vascular channel. Exposure to methylglyoxal (MG), a dicarbonyl stressor associated with diabetic circulatory milieu increases cancer cell intravasation and adhesion through the vascular channel. This can be driven by MG-induced endothelial senescence and shedding, but also by the ability of MG to degrade lrBM and pathologically cross-link Collagen I, diminishing cell-ECM adhesion. Thus, dicarbonyl stress attenuates homeostatic barriers to cancer intravasation, exacerbating metastasis.

Combining Quantitative Proteomics and Interactomics for a Deeper Insight into Molecular Differences between Human Cell Lines

In modern biomedical research, cultivable cell lines are an indispensable tool, and the selection of cell lines that exhibit specific functional profiles is often critical to success. Cellular functional pathways have evolved through the selection of protein intra- and intermolecular interactions collectively referred to as the interactome. In the present work, quantitative in vivo protein cross-linking and mass spectrometry were used to probe large-scale protein interactome differences among three commonly employed human cell lines, namely, HEK293, MCF-7, and HeLa cells. These data illustrated highly reproducible quantitative interactome levels with R2 values larger than 0.8 for all biological replicates. Proteome abundance levels were also measured using data-independent acquisition quantitative proteomics methods. Combining quantitative interactome and proteome information allowed the visualization of cell type-specific interactome changes mediated by proteome level adaptations and independently regulated interactome changes to gain deeper insight into possible drivers of these changes. Among the largest detected alterations in protein interactions and conformations are changes in cytoskeletal proteins, RNA-binding proteins, chromatin remodeling complexes, mitochondrial proteins, and others. Overall, these data demonstrate the utility and reproducibility of quantitative cross-linking to study system-level interactome variations. Moreover, these results illustrate how combined quantitative interactomics and proteomics can provide unique insight into cellular functional landscapes.

S-p-bromobenzyl-glutathione cyclopentyl diester (BBGC) as novel therapeutic strategy to enhance trabectedin anti-tumor effect in soft tissue sarcoma preclinical models

Trabectedin, approved for the treatment of soft tissue sarcoma (STS), interferes with cell division and genetic transcription processes. Due to its strong anti-tumor activity in only certain histotypes, several studies on trabectedin combinations are currently ongoing to improve its efficacy. In this study, we aimed to investigate novel potential therapeutic strategies to enhance the anti-tumor effect of trabectedin using integrated in silico, in vitro, and in vivo approaches. For in silico analysis, we screened two public datasets, GSEA M5190 and TCGA SARC. Fibrosarcoma, leiomyosarcoma, dedifferentiated, and myxoid liposarcoma cell lines were used for in vitro studies. For in vivo experiments, fibrosarcoma orthotopic murine model was developed. In silico analysis identified Glo1 as the only druggable target upregulated after trabectedin treatment and correlated with poor prognosis. The specific Glo1 inhibitor, S-p-bromobenzylglutathione cyclopentyl diester (BBGC), increased trabectedin cytotoxicity in STS cells, and restored drug sensitivity in myxoid liposarcoma cells resistant to trabectedin. Moreover, the combined treatment with BBGC and trabectedin had a synergistic antitumor effect in vivo without any additional toxicity to mice. Based on these results, we believe that BBGC warrants further investigation to evaluate its potential clinical use in combination with trabectedin.

The Impact of Low Protein Diet on the Molecular and Cellular Development of the Fetal Kidney

Background

Low nephron number has a direct impact on the development of hypertension and chronic kidney disease later in life. While intrauterine growth restriction caused by maternal low protein diet (LPD) is thought to be a significant cause of reduced nephron endowment in impoverished communities, its influence on the cellular and molecular processes which drive nephron formation are poorly understood.

Methods

We conducted a comprehensive characterization of the impact of LPD on kidney development using tomographic and confocal imaging to quantify changes in branching morphogenesis and the cellular and morphological features of nephrogenic niches across development. These analyses were paired with single-cell RNA sequencing to dissect the transcriptional changes that LPD imposes during renal development to affect nephron number.

Results

Single cell analysis at E14.5 and P0 revealed differences in the expression of genes and pathways involved in metabolism, cell cycle, epigenetic regulators and reciprocal inductive signals in most cell types analyzed, yielding imbalances and shifts in cellular energy production and cellular trajectories. In the nephron progenitor cells, LPD impeded cellular commitment and differentiation towards pre-tubular and renal vesicle structures. Confocal microscopy revealed a reduction in the number of pre-tubular aggregates and proliferation in nephron progenitor cells. We also found changes in branching morphogenesis, with a reduction in cell proliferation in the ureteric tips as well as reduced tip and tip parent lengths by optical projection tomography which causes patterning defects.

Conclusions

This unique profiling demonstrates how a fetal programming defect leads to low nephron endowment which is intricately linked to changes in both branching morphogenesis and the commitment of nephron progenitor cells. The commitment of progenitor cells is pivotal for nephron formation and is significantly influenced by nutritional factors, with a low protein diet driving alterations in this program which directly results in a reduced nephron endowment.

Significance Statement

While a mother's diet can negatively impact the number of nephrons in the kidneys of her offspring, the root cellular and molecular drivers of these deficits have not been rigorously explored. In this study we use advanced imaging and gene expression analysis in mouse models to define how a maternal low protein diet, analogous to that of impoverished communities, results in reduced nephron endowment. We find that low protein diet has pleiotropic effects on metabolism and the normal developmental programs of gene expression. These profoundly impact the process of branching morphogenesis necessary to establish niches for nephron generation and change cell behaviors which regulate how and when nephron progenitor cells commit to differentiation.

Combining quantitative proteomics and interactomics for a deeper insight into molecular differences between human cell lines

Cellular functional pathways have evolved through selection based on fitness benefits conferred through protein intra- and inter-molecular interactions that comprise all protein conformational features and protein-protein interactions, collectively referred to as the interactome. While the interactome is regulated by proteome levels, it is also regulated independently by, post translational modification, co-factor, and ligand levels, as well as local protein environmental factors, such as osmolyte concentration, pH, ionic strength, temperature and others. In modern biomedical research, cultivatable cell lines have become an indispensable tool, with selection of optimal cell lines that exhibit specific functional profiles being critical for success in many cases. While it is clear that cell lines derived from different cell types have differential proteome levels, increased understanding of large-scale functional differences requires additional information beyond abundance level measurements, including how protein conformations and interactions are altered in certain cell types to shape functional landscapes. Here, we employed quantitative in vivo protein cross-linking coupled to mass spectrometry to probe large-scale protein conformational and interaction changes among three commonly employed human cell lines, HEK293, MCF-7, and HeLa cells. Isobaric quantitative Protein Interaction Reporter (iqPIR) technologies were used to obtain quantitative values of cross-linked peptides across three cell lines. These data illustrated highly reproducible (R2 values larger than 0.8 for all biological replicates) quantitative interactome levels across multiple biological replicates. We also measured protein abundance levels in these cells using data independent acquisition quantitative proteomics methods. Combining quantitative interactome and proteomics information allowed visualization of cell type-specific interactome changes mediated by proteome level adaptations as well as independently regulated interactome changes to gain deeper insight into possible drivers of these changes. Among the biggest detected alterations in protein interactions and conformations are changes in cytoskeletal proteins, RNA-binding proteins, chromatin remodeling complexes, mitochondrial proteins, and others. Overall, these data demonstrate the utility and reproducibility of quantitative cross-linking to study systems-level interactome variations. Moreover, these results illustrate how combined quantitative interactomics and proteomics can provide unique insight on cellular functional landscapes.

Glyoxalase 1: Emerging biomarker and therapeutic target in cervical cancer progression

INTRODUCTION

Cervical cancer presents a significant global health challenge, disproportionately impacting underserved populations with limited access to healthcare. Early detection and effective management are vital in addressing this public health concern. This study focuses on Glyoxalase-1 (GLO1), an enzyme crucial for methylglyoxal detoxification, in the context of cervical cancer.

METHODS

We assessed GLO1 expression in cervical cancer patient samples using immunohistochemistry. In vitro experiments using HeLa cells were conducted to evaluate the impact of GLO1 inhibition on cell viability and migration. Single-cell RNA sequencing (scRNA-seq) and gene set variation analysis were utilized to investigate the role of GLO1 in the metabolism of cervical cancer. Additionally, public microarray data were analyzed to determine GLO1 expression across various stages of cervical cancer.

RESULTS

Our analysis included 58 cervical cancer patients, and showed that GLO1 is significantly upregulated in cervical cancer tissues compared to normal cervical tissues, independent of pathological findings and disease stage. In vitro experiments indicated that GLO1 inhibition by S-p-bromobenzylglutathione cyclopentyl diester decreased cell viability and migration in cervical cancer cell lines. Analyses of scRNA-seq data and public gene expression datasets corroborated the overexpression of GLO1 and its involvement in cancer metabolism, particularly glycolysis. An examination of expression data from precancerous lesions revealed a progressive increase in GLO1 expression from normal tissue to invasive cervical cancer.

CONCLUSIONS

This study highlights the critical role of GLO1 in the progression of cervical cancer, presenting it as a potential biomarker and therapeutic target. These findings contribute valuable insights towards personalized treatment approaches and augment the ongoing efforts to combat cervical cancer. Further research is necessary to comprehensively explore GLO1's potential in clinical applications.

Glyoxalase System in Breast and Ovarian Cancers: Role of MEK/ERK/SMAD1 Pathway

The glyoxalase system, comprising GLO1 and GLO2 enzymes, is integral in detoxifying methylglyoxal (MGO) generated during glycolysis, with dysregulation implicated in various cancer types. The MEK/ERK/SMAD1 signaling pathway, crucial in cellular processes, influences tumorigenesis, metastasis, and angiogenesis. Altered GLO1 expression in cancer showcases its complex role in cellular adaptation and cancer aggressiveness. GLO2 exhibits context-dependent functions, contributing to both proapoptotic and antiapoptotic effects in different cancer scenarios. Research highlights the interconnected nature of these systems, particularly in ovarian cancer and breast cancer. The glyoxalase system's involvement in drug resistance and its impact on the MEK/ERK/SMAD1 signaling cascade underscore their clinical significance. Furthermore, this review delves into the urgent need for effective biomarkers, exemplified in ovarian cancer, where the RAGE-ligand pathway emerges as a potential diagnostic tool. While therapeutic strategies targeting these pathways hold promise, this review emphasizes the challenges posed by context-dependent effects and intricate crosstalk within the cellular milieu. Insights into the molecular intricacies of these pathways offer a foundation for developing innovative therapeutic approaches, providing hope for enhanced cancer diagnostics and tailored treatment strategies.

Molecular Assessment of Methylglyoxal-Induced Toxicity and Therapeutic Approaches in Various Diseases: Exploring the Interplay with the Glyoxalase System

This comprehensive exploration delves into the intricate interplay of methylglyoxal (MG) and glyoxalase 1 (GLO I) in various physiological and pathological contexts. The linchpin of the narrative revolves around the role of these small molecules in age-related issues, diabetes, obesity, cardiovascular diseases, and neurodegenerative disorders. Methylglyoxal, a reactive dicarbonyl metabolite, takes center stage, becoming a principal player in the development of AGEs and contributing to cell and tissue dysfunction. The dual facets of GLO I-activation and inhibition-unfold as potential therapeutic avenues. Activators, spanning synthetic drugs like candesartan to natural compounds like polyphenols and isothiocyanates, aim to restore GLO I function. These molecular enhancers showcase promising outcomes in conditions such as diabetic retinopathy, kidney disease, and beyond. On the contrary, GLO I inhibitors emerge as crucial players in cancer treatment, offering new possibilities in diseases associated with inflammation and multidrug resistance. The symphony of small molecules, from GLO I activators to inhibitors, presents a nuanced understanding of MG regulation. From natural compounds to synthetic drugs, each element contributes to a molecular orchestra, promising novel interventions and personalized approaches in the pursuit of health and wellbeing. The abstract concludes with an emphasis on the necessity of rigorous clinical trials to validate these findings and acknowledges the importance of individual variability in the complex landscape of health.

Deletion of Glyoxalase 1 exacerbates acetaminophen-induced hepatotoxicity in mice

Acetaminophen (APAP) overdose triggers a cascade of intracellular oxidative stress events culminating in acute liver injury. The clinically used antidote, N-acetylcysteine (NAC) has a narrow therapeutic window and early treatment is essential for satisfactory therapeutic outcome. For more versatile therapies that can be effective even at late-presentation, the intricacies of APAP-induced hepatotoxicity must be better understood. Accumulation of advanced glycation end-products (AGEs) and consequent activation of the receptor for AGEs (RAGE) are considered one of the key mechanistic features of APAP toxicity. Glyoxalase-1 (Glo-1) regulates AGE formation by limiting the levels of methylglyoxal (MEG). In this study, we studied the relevance of Glo-1 in APAP mediated activation of RAGE and downstream cell-death cascades. Constitutive Glo-1 knockout mice (GKO) and a cofactor of Glo-1, ψ-GSH, were employed as tools. Our findings show elevated oxidative stress, activation of RAGE and hepatocyte necrosis through steatosis in GKO mice treated with high-dose APAP compared to wild type controls. A unique feature of the hepatic necrosis in GKO mice is the appearance of microvesicular steatosis as a result of centrilobular necrosis, rather than inflammation seen in wild type. The GSH surrogate and general antioxidant, ψ-GSH alleviated APAP toxicity irrespective of Glo-1 status, suggesting that oxidative stress being the primary driver of APAP toxicity. Overall, exacerbation of APAP hepatotoxicity in GKO mice suggests the importance of this enzyme system in antioxidant defense against initial stages of APAP overdose.

Epigenetic meets metabolism: novel vulnerabilities to fight cancer

Histones undergo a plethora of post-translational modifications (PTMs) that regulate nucleosome and chromatin dynamics and thus dictate cell fate. Several evidences suggest that the accumulation of epigenetic alterations is one of the key driving forces triggering aberrant cellular proliferation, invasion, metastasis and chemoresistance pathways. Recently a novel class of histone "non-enzymatic covalent modifications" (NECMs), correlating epigenome landscape and metabolic rewiring, have been described. These modifications are tightly related to cell metabolic fitness and are able to impair chromatin architecture. During metabolic reprogramming, the high metabolic flux induces the accumulation of metabolic intermediate and/or by-products able to react with histone tails altering epigenome homeostasis. The accumulation of histone NECMs is a damaging condition that cancer cells counteracts by overexpressing peculiar "eraser" enzymes capable of removing these modifications preserving histones architecture. In this review we explored the well-established NECMs, emphasizing the role of their corresponding eraser enzymes. Additionally, we provide a parterre of drugs aiming to target those eraser enzymes with the intent to propose novel routes of personalized medicine based on the identification of epi-biomarkers which might be selectively targeted for therapy. Video Abstract.