Fueling the fire: emerging role of the hexosamine biosynthetic pathway in cancer

Factors influencing the bioactivity of natural matrices: The case of osmolarity-dependent modulation of cell viability by different dilutions of camel urines

The widespread practice of dromedary urinotherapy as a remedy for various illnesses, including cancer, is well-established in traditional dromedary countries. Researchers attempted to demonstrate anticancer properties of camel urine through in vitro experiments with debated outcomes. Notably, two critical aspects remained unexplored in those assays: (i) the osmolarity of tested urines, which can significantly influence in vitro results; (ii) the potential morphological changes of cells, following exposure to camel urines. In this study, we addressed these gaps by evaluating the osmolarity-dependent modulation of cell viability in human renal cell lines. In this regard, we assessed the impact of hyperosmolar mannitol-based solutions and dromedary urine on the viability and morphology of human non-tumor (HK2) and tumor renal cells (Caki-1). The results indicate that cell viability or morphology in both HK2 and Caki-1 cells are not significantly affected only if mannitol-induced hyperosmolarity is lower than 500 mOsm/L. Notably, when exposed to urine solution, diluted to <500 mOsm/L, statistically significant antiproliferative effects were observed primarily in Caki-1 cells (in presence of two out of ten tested urine samples). Conversely, alterations in cell morphology were observed exclusively in HK2 cells when exposed to the same diluted camel urines. In order to investigate, at molecular level, the observed antiproliferative effects, a preliminary metabolomics analysis of the tested urine samples was performed to identify potential bioactive compounds. The Nuclear Magnetic Resonance (NMR) metabolic profiling revealed the presence of three antioxidant compounds, namely trigonelline, pyruvic acid and N-acetylglucosamine. In conclusion, our results highlight the importance of considering the critical role of osmolarity when evaluating the bioactive properties of camel urine in vitro, which should not be used to treat any illness as it is. Conversely, it can be considered the possibility to use camel urines as a source of bioactive compounds.

The roles of OGT and its mechanisms in cancer

O-linked-N-acetylglucosaminylation (O-GlcNAcylation) is a common and important post-translational modification (PTM) linking O-linked β-N-acetylglucosamine (O-GlcNAc) to serine and threonine residues in proteins. Extensive research indicates its impact on target protein stability, activity, and interactions. O-linked N-acetylglucosamine transferase (OGT) is a critical enzyme that catalyzes O-GlcNAc modification, responsible for adding O-GlcNAc to proteins. OGT and O-GlcNAcylation are overexpressed in many tumors and closely associated with tumor growth, invasion, metabolism, drug resistance, and immune evasion. This review delineates the biochemical functions of OGT and summarizes its effects and mechanisms in tumors. Targeting OGT presents a promising novel approach for treating human malignancies.

Metabolomics and proteomics reveal the inhibitory effect of Lactobacillus crispatus on cervical cancer

Cervical cancer remains a significant global health issue due to its high morbidity and mortality rates. Recently, Lactobacillus crispatus has been recognized for its crucial role in maintaining cervical health. While some studies have explored the use of L. crispatus to mitigate cervical cancer, the underlying mechanisms remain largely unknown. In this study, we employed non-targeted proteomics and metabolomics to investigate how L. crispatus affects the growth of cervical cancer cells (SiHa) and normal cervical cells (Ect1/E6E7). Our findings indicated that the inhibitory effect of L. crispatus on SiHa cells was associated with various biological processes, notably the ferroptosis pathway. Specifically, L. crispatus was found to regulate the expression of proteins such as HMOX1, SLC39A14, VDAC2, ACSL4, and LPCAT3 by SiHa cells, which are closely related to ferroptosis. Additionally, it activated the tricarboxylic acid (TCA) cycle in SiHa cells, leading to increased levels of reactive oxygen species (ROS) and lipid peroxides (LPO). These results revealed the therapeutic potential of L. crispatus in targeting the ferroptosis pathway for cervical cancer treatment, opening new avenues for research and therapy in cervical cancer.

Downregulation of O-GlcNAc transferase activity impairs basal autophagy and late endosome positioning under nutrient-rich conditions in human colon cells

Autophagy is a critical catabolic pathway that enables cells to survive and adapt to stressful conditions, especially nutrient deprivation. The fusion of autophagic vacuoles with lysosomes is the final step of autophagy, which degrades the engulfed contents into metabolic precursors for re-use by the cell. O-GlcNAc transferase (OGT) plays a crucial role in regulating autophagy flux in response to nutrient stress, particularly by targeting key proteins involved in autophagosome-lysosome fusion. However, the role of OGT in basal autophagy, which occurs at a low and constitutive levels under growth conditions, remains poorly understood. Silencing or inhibition of OGT was used to compare the effect of OGT downregulation on autophagy flux in the non-cancerous CCD841CoN and cancerous HCT116 human colon cell lines under nutrient-rich conditions. We provide evidence that the reduction of OGT activity impairs the maturation of autophagosomes, thereby blocking the completion of basal autophagy in both cell lines. Additionally, OGT inhibition results in the accumulation of lysosomes and enlarged late endosomes in the perinuclear region, as demonstrated by confocal imaging. This is associated with a defect in the localization of the small GTPase Rab7 to these organelles. The regulation of transport and fusion events between the endosomal and lysosomal compartments is crucial for maintaining the autophagic flux. These findings suggest an interplay between OGT and the homeostasis of the endolysosomal network in human cells.

FOXM1 Upregulates O-GlcNAcylation Level Via The Hexosamine Biosynthesis Pathway to Promote Angiogenesis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) presents significant challenges in treatment and prognosis because of its aggressive nature and high metastatic potential. This study aims to investigate the role of the hexosamine biosynthesis pathway (HBP) and its association with HCC progression and prognosis. We identified SPP1 and FOXM1 as hub genes within the HBP pathway, showing their correlation with poor prognosis and late-stage progression. In addition, the analysis uncovered the complex participation of the HBP pathway in nutrients and oxygen reactions, PI3K-AKT signaling, AMPK activation, and angiogenesis regulation. The disruption of these pathways is pivotal in influencing the growth and progression of HCC. Targeting the HBP presents a promising therapeutic approach to modulate the tumor microenvironment, thereby enhancing the efficacy of immunotherapy. In addition, FOXM1 was identified as the HBP pathway regulator, influencing cellular O-GlcNAcylation level and VEGF secretion, thereby promoting angiogenesis in HCC. Inhibition of O-GlcNAcylation significantly hindered angiogenesis, which is suggested as a potential avenue for therapeutic intervention. Our research demonstrates the practicality of using the HBP-related gene as a prognostic marker in liver cancer patients and suggests targeting FOXM1 as a novel avenue for personalized therapy.

The OGT-c-Myc-PDK2 axis rewires the TCA cycle and promotes colorectal tumor growth

Deregulated glucose metabolism termed the "Warburg effect" is a fundamental feature of cancers, including the colorectal cancer. This is typically characterized with an increased rate of glycolysis, and a concomitant reduced rate of the tricarboxylic acid (TCA) cycle metabolism as compared to the normal cells. How the TCA cycle is manipulated in cancer cells remains unknown. Here, we show that O-linked N-acetylglucosamine (O-GlcNAc) regulates the TCA cycle in colorectal cancer cells. Depletion of OGT, the sole transferase of O-GlcNAc, significantly increases the TCA cycle metabolism in colorectal cancer cells. Mechanistically, OGT-catalyzed O-GlcNAc modification of c-Myc at serine 415 (S415) increases c-Myc stability, which transcriptionally upregulates the expression of pyruvate dehydrogenase kinase 2 (PDK2). PDK2 phosphorylates pyruvate dehydrogenase (PDH) to inhibit the activity of mitochondrial pyruvate dehydrogenase complex, which reduces mitochondrial pyruvate metabolism, suppresses reactive oxygen species production, and promotes xenograft tumor growth. Furthermore, c-Myc S415 glycosylation levels positively correlate with PDK2 expression levels in clinical colorectal tumor tissues. This study highlights the OGT-c-Myc-PDK2 axis as a key mechanism linking oncoprotein activation with deregulated glucose metabolism in colorectal cancer.

Manipulating mannose metabolism as a potential anticancer strategy

Cancer cells acquire metabolic advantages over their normal counterparts regarding the use of nutrients for sustained cell proliferation and cell survival in the tumor microenvironment. Notable among the metabolic traits in cancer cells is the Warburg effect, which is a reprogrammed form of glycolysis that favors the rapid generation of ATP from glucose and the production of biological macromolecules by diverting glucose into various metabolic intermediates. Meanwhile, mannose, which is the C-2 epimer of glucose, has the ability to dampen the Warburg effect, resulting in slow-cycling cancer cells that are highly susceptible to chemotherapy. This anticancer effect of mannose appears when its catabolism is compromised in cancer cells. Moreover, de novo synthesis of mannose within cancer cells has also been identified as a potential target for enhancing chemosensitivity through targeting glycosylation pathways. The underlying mechanisms by which alterations in mannose metabolism induce cancer cell vulnerability are just beginning to emerge. This review summarizes the current state of our knowledge of mannose metabolism and provides insights into its manipulation as a potential anticancer strategy.

Glycosylation: mechanisms, biological functions and clinical implications

Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.

Ketomimetic Nutrients Trigger a Dual Metabolic Defense in Breast Cancer Cells

While the triggers for the metastatic transformation of breast cancer (BC) cells remain unknown, recent evidence suggests that intrinsic cellular metabolism could be a crucial driver of migratory disposition and chemoresistance. Aiming to decode the molecular mechanisms involved in BC cell metabolic maneuvering, we study how a ketomimetic (ketone body rich, low glucose) medium affects Doxorubicin (DOX) susceptibility and invasive disposition of BC cells. We quantified glycocalyx sialylation and found an inverse correlation with DOX-induced cytotoxicity and DOX internalization. These measurements were coupled with single-cell metabolic imaging, bulk migration studies, along with transcriptomic and metabolomic analyses. Our findings revealed that a ketomimetic medium enhances chemoresistance and invasive disposition of BC cells via two main oncogenic pathways: hypersialylation and lipid synthesis. We propose that the crosstalk between these pathways, juxtaposed at the synthesis of the glycan precursor UDP-GlcNAc, furthers advancement of a metastatic phenotype in BC cells under ketomimetic conditions.

Metabolic pathways for glucose and fructose: I synthesis and metabolism of fructose by ovine conceptuses†

Fructose, the most abundant hexose sugar in fetal fluids and the blood of sheep and other ungulates and cetaceans, is synthesized from glucose via the polyol pathway in trophectoderm and chorion. However, the cell-specific and temporal expression of enzymes for the synthesis and metabolism of fructose in sheep conceptuses (embryo and placental membranes) and placentomes has not been characterized. This study characterized key enzymes involved in fructose synthesis and metabolism by ovine conceptuses throughout pregnancy. Day 17 conceptuses expressed mRNAs for the polyol pathway (SORD and AKR1B1) and glucose and fructose metabolism (HK1, HK2, G6PD, OGT, and FBP), but not those required for gluconeogenesis (G6Pase or PCK). Ovine placentomes also expressed mRNAs for SORD, AKR1B1, HK1, and OGT. Fructose can be metabolized via the ketohexokinase (KHK) pathway, and isoforms, KHK-A and KHK-C, were expressed in ovine conceptuses from Day 16 of pregnancy and placentomes during pregnancy in a cell-specific manner. The KHK-A protein was more abundant in the trophectoderm and cotyledons of placentomes, while KHK-C protein was more abundant in the endoderm of Day 16 conceptuses and the chorionic epithelium in placentomes. Expression of KHK mRNAs in placentomes was greatest at Day 30 of pregnancy (P < 0.05), but not different among days later in gestation. These results provide novel insights into the synthesis and metabolism of fructose via the uninhibited KHK pathway in ovine conceptuses to generate ATP via the tricarboxylic cycle, as well as substrates for the pentose cycle, hexosamine biosynthesis pathway, and one-carbon metabolism required for conceptus development throughout pregnancy.

O-GlcNAcase regulates pluripotency states of human embryonic stem cells

Understanding the regulation of human embryonic stem cells (hESCs) pluripotency is critical to advance the field of developmental biology and regenerative medicine. Despite the recent progress, molecular events regulating hESC pluripotency, especially the transition between naive and primed states, still remain unclear. Here we show that naive hESCs display lower levels of O-linked N-acetylglucosamine (O-GlcNAcylation) than primed hESCs. O-GlcNAcase (OGA), the key enzyme catalyzing the removal of O-GlcNAc from proteins, is highly expressed in naive hESCs and is important for naive pluripotency. Depletion of OGA accelerates naive-to-primed pluripotency transition. OGA is transcriptionally regulated by EP300 and acts as a transcription regulator of genes important for maintaining naive pluripotency. Moreover, we profile protein O-GlcNAcylation of the two pluripotency states by quantitative proteomics. Together, this study identifies OGA as an important factor of naive pluripotency in hESCs and suggests that O-GlcNAcylation has a broad effect on hESCs homeostasis.

Salivary metabolomics in early detection of oral squamous cell carcinoma - a meta-analysis

INTRODUCTION

Oral squamous cell carcinoma (OSCC) represents the most prevalent form of oral cancer. Potentially malignant disorders of oral mucosa exhibit an elevated propensity for malignant progression. A substantial proportion of cases are discerned during advanced stages, significantly impacting overall survival. This investigation aims to ascertain salivary metabolites with potential utility in the early detection of OSCC.

METHODS

A search encompassing PubMed, EMBASE, Scopus, Ovid, Science Direct, and Web of Science databases was conducted to identify eligible articles. The search strategy employed precise terms. The quality assessment of the included studies was executed using the QUADAS 2 ROB tool. This was registered with PROSPERO CRD42021278217.

RESULTS

Upon removing duplicate articles and publications that didn't satisfy the inclusion criteria, seven articles were included in the current study. The Random Effects Maximum Likelihood (REML) model adopted for quantitative synthesis identified Nacetyl glucosamine as the sole metabolite in two studies included in this metaanalysis. The pathways significantly influenced by these identified metabolites were delineated.

CONCLUSION

This study highlights Nacetyl glucosamine as a distinctive metabolite with the potential to serve as an early diagnostic marker for OSCC. Nevertheless, further research is warranted to validate its clinical utility.

Mitochondrial DNA variants and microbiota: An experimental strategy to identify novel therapeutic potential in chronic inflammatory diseases

We previously demonstrated that mice carrying natural mtDNA variants of the FVB/NJ strain (m.7778 G>T in the mt-Atp8 gene in mitochondrial complex V), namely C57BL/6 J-mtFVB/NJ (B6-mtFVB), exhibited (i) partial protection from experimental skin inflammatory diseases in an anti-murine type VII collagen antibody-induced skin inflammation model and psoriasiform dermatitis model; (ii) significantly altered metabolites, including short-chain fatty acids, according to targeted metabolomics of liver, skin and lymph node samples; and (iii) a differential composition of the gut microbiota according to bacterial 16 S rRNA gene sequencing of stool samples compared to wild-type C57BL/6 J (B6) mice. To further dissect these disease-contributing factors, we induced an experimental antibody-induced skin inflammatory disease in gnotobiotic mice. We performed shotgun metagenomic sequencing of caecum contents and untargeted metabolomics of liver, CD4+ T cell, and caecum content samples from conventional B6-mtFVB and B6 mice. We identified D-glucosamine as a candidate mediator that ameliorated disease severity in experimental antibody-induced skin inflammation by modulating immune cell function in T cells, neutrophils and macrophages. Because mice carrying mtDNA variants of the FVB/NJ strain show differential disease susceptibility to a wide range of experimental diseases, including diet-induced atherosclerosis in low-density lipoprotein receptor knockout mice and collagen antibody-induced arthritis in DBA/1 J mice, this experimental approach is valuable for identifying novel therapeutic options for skin inflammatory conditions and other chronic inflammatory diseases to which mice carrying specific mtDNA variants show differential susceptibility.

O-GlcNAcylation of TRIM29 and OGT translation forms a feedback loop to promote adaptive response of PDAC cells to glucose deficiency

PURPOSE

Glucose not only provides energy for tumor cells, but also provides various biomolecules that are essential for their survival, proliferation and invasion. Therefore, it is of great clinical significance to understand the mechanism of how tumor cells adapt to metabolic stress and maintain their survival. The aim of this research was to study the critical role of OGT and TRIM29 O-GlcNAc modification driven adaptability of PDAC cells to low glucose stress, which might have important medical implications for PDAC therapy.

METHODS

Western blotting, mass spectrometry and WGA-immunoprecipitation were used to examined the levels of OGT and O-GlcNAc glycosylated proteins in BxPC3 and SW1990 cells in normal culture and under glucose deprivation conditions. Crystal violet assay, flow cytometry, RIP, RT-qPCR, protein stability assay, biotin pull down were used to investigate the mechanism of OGT and TRIM29-mediated adaptive response to glucose deficiency in PDAC cells.

RESULTS

The current study found that under the condition of low glucose culture, the levels of OGT and O-GlcNAc glycosylation in PDAC cells were significantly higher than those in normal culture. Moreover, the high expression of OGT has a protective effect on PDAC cells under low glucose stress. This study confirmed that there was no significant change in mRNA level and protein degradation of OGT under low glucose stress, which was mainly reflected in the increase of protein synthesis. In addition, O-GlcNAc modification at T120 site plays a critical role in the metabolic adaptive responses mediated by TRIM29.

CONCLUSIONS

Taken together, our study indicated that O-GlcNAcylation of TRIM29 at T120 site and OGT translation forms a loop feedback to facilitate survival of PDAC under glucose deficiency.

Macropinocytosis at the crossroad between nutrient scavenging and metabolism in cancer

Macropinocytosis (MP), the actin-dependent bulk uptake of extracellular fluids, plays a central role in nutrient scavenging, allowing cancer cells to sustain their growth in the hypoxic and nutrient-deprived microenvironment often found in solid tumours. The lack of soluble nutrients and several oncogenic signalling pathways, with RAS being the most studied, push MP-dependent internalisation of extracellular proteins, which are then digested in the lysosomes, replenishing the intracellular nutrient pools. This review will highlight recent advances in understanding how MP is regulated in hypoxic cancers, how it impinges on chemoresistance, and how different MP cargos facilitate tumour growth. Finally, I will highlight the crosstalk between MP and extracellular matrix receptors.

Diabetes and further risk of cancer: a nationwide population-based study

BACKGROUND

Individuals with diabetes have a significantly higher risk of developing various forms of cancer, and the potential biological links between these two diseases are not completely understood.

METHODS

This was a longitudinal retrospective nationwide cohort study, a study design that allows us to examine the natural course of cancer development over an extended period of time with a large sample size. Initially, 3,111,975 and 22,208,395 eligible patients aged ≥ 20 years with and without diabetes, respectively, were matched by age, sex, and the Charlson comorbidity index. Ultimately, 1,751,457 patients were selected from each group. Stratified populations for diabetic retinopathy (DR) (n = 380,822) and without DR (n = 380,822) as well as proliferative DR (PDR) (n = 141,150) and non-proliferative DR (NPDR) (n = 141,150) were analyzed in this study. The main outcome measure was the first-time diagnosis of cancer during the follow-up period.

RESULTS

We observed a 20% higher risk of total cancer incidence [hazard ratios (HR), 1.20; p < 0.001] in the diabetes cohort compared to the non-diabetes cohort. The highest HR was observed for liver and pancreas cancers. Moderately increased risks were observed for oral, colon, gallbladder, reproductive (female), kidney, and brain cancer. Furthermore, there was a borderline significantly increased risk of stomach, skin, soft tissue, female breast, and urinary tract (except kidney) cancers and lymphatic and hematopoietic malignancies. The stratified analysis revealed that the total cancer incidence was significantly higher in the DR cohort compared to the non-DR cohort (HR, 1.31; p < 0.001), and there was a borderline increased risk in the PDR cohort compared to the NPDR cohort (HR, 1.13; p = 0.001).

CONCLUSIONS

This study provides large-scale, nationwide, population-based evidence that diabetes is independently associated with an increased risk of subsequent development of total cancer and cancer at specific sites. Notably, this risk may further increase when DR develops.

O-GlcNAcylation: roles and potential therapeutic target for bone pathophysiology

O-linked N-acetylglucosamine (O-GlcNAc) protein modification (O-GlcNAcylation) is a critical post-translational modification (PTM) of cytoplasmic and nuclear proteins. O-GlcNAcylation levels are regulated by the activity of two enzymes, O-GlcNAc transferase (OGT) and O‑GlcNAcase (OGA). While OGT attaches O-GlcNAc to proteins, OGA removes O-GlcNAc from proteins. Since its discovery, researchers have demonstrated O-GlcNAcylation on thousands of proteins implicated in numerous different biological processes. Moreover, dysregulation of O-GlcNAcylation has been associated with several pathologies, including cancers, ischemia-reperfusion injury, and neurodegenerative diseases. In this review, we focus on progress in our understanding of the role of O-GlcNAcylation in bone pathophysiology, and we discuss the potential molecular mechanisms of O-GlcNAcylation modulation of bone-related diseases. In addition, we explore significant advances in the identification of O-GlcNAcylation-related regulators as potential therapeutic targets, providing novel therapeutic strategies for the treatment of bone-related disorders.

TRIM14 suppressed the progression of NSCLC via hexosamine biosynthesis pathway

Tripartite Motif 14 (TRIM14) is an oncoprotein that belongs to the E3 ligase TRIM family, which is involved in the progression of various tumors except for non-small cell lung carcinoma (NSCLC). However, little is currently known regarding the function and related mechanisms of TRIM14 in NSCLC. Here, we found that the TRIM14 protein was downregulated in lung adenocarcinoma tissues compared with the adjacent tissues, which can suppress tumor cell proliferation and migration both in vitro and in vivo. Moreover, TRIM14 can directly bind to glutamine fructose-6-phosphate amidotransferase 1 (GFAT1), which in turn results in the degradation of GFAT1 and reduced O-glycosylation levels. GFAT1 is a key enzyme in the rate-limiting step of the hexosamine biosynthetic pathway (HBP). Replenishment of N-acetyl-d-glucosamine can successfully reverse the inhibitory effect of TRIM14 on the NSCLC cell growth and migration as expected. Collectively, our data revealed that TRIM14 suppressed NSCLC cell proliferation and migration through ubiquitination and degradation of GFAT1, providing a new regulatory role for TRIM14 on HBP.

Glutamine metabolism, a double agent combating or fuelling hepatocellular carcinoma

The reprogramming of glutamine metabolism is a key event in cancer more generally and in hepatocellular carcinoma (HCC) in particular. Glutamine consumption supplies tumours with ATP and metabolites through anaplerosis of the tricarboxylic acid cycle, while glutamine production can be enhanced by the overexpression of glutamine synthetase. In HCC, increased glutamine production is driven by activating mutations in the CTNNB1 gene encoding β-catenin. Increased glutamine synthesis or utilisation impacts tumour epigenetics, oxidative stress, autophagy, immunity and associated pathways, such as the mTOR (mammalian target of rapamycin) pathway. In this review, we will discuss studies which emphasise the pro-tumoral or tumour-suppressive effect of glutamine overproduction. It is clear that more comprehensive studies are needed as a foundation from which to develop suitable therapies targeting glutamine metabolic pathways, depending on the predicted pro- or anti-tumour role of dysregulated glutamine metabolism in distinct genetic contexts.

Regulation of myocardial glucose metabolism by YAP/TAZ signaling

The heart utilizes glucose and its metabolites as both energy sources and building blocks for cardiac growth and survival under both physiological and pathophysiological conditions. YAP/TAZ, transcriptional co-activators of the Hippo pathway, are key regulators of cell proliferation, survival, and metabolism in many cell types. Increasing lines of evidence suggest that the Hippo-YAP/TAZ signaling pathway is involved in the regulation of both physiological and pathophysiological processes in the heart. In particular, YAP/TAZ play a critical role in mediating aerobic glycolysis, the Warburg effect, in cardiomyocytes. Here, we summarize what is currently known about YAP/TAZ signaling in the heart by focusing on the regulation of glucose metabolism and its functional significance.

Metabolic alterations and mitochondrial dysfunction in human airway BEAS-2B cells exposed to vanadium pentoxide

Vanadium pentoxide (V+5) is a hazardous material that has drawn considerable attention due to its wide use in industrial sectors and increased release into environment from human activities. It poses potential adverse effects on animals and human health, with pronounced impact on lung physiology and functions. In this study, we investigated the metabolic response of human bronchial epithelial BEAS-2B cells to low-level V+5 exposure (0.01, 0.1, and 1 ppm) using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Exposure to V+5 caused extensive changes to cellular metabolism in BEAS-2B cells, including TCA cycle, glycolysis, fatty acids, amino acids, amino sugars, nucleotide sugar, sialic acid, vitamin D3, and drug metabolism, without causing cell death. Altered mitochondrial structure and function were observed with as low as 0.01 ppm (0.2 μM) V+5 exposure. In addition, decreased level of E-cadherin, the prototypical epithelial marker of epithelial-mesenchymal transition (EMT), was observed following V+5 treatment, supporting potential toxicity of V+5 at low levels. Taken together, the present study shows that V+5 has adverse effects on mitochondria and the metabolome which may result in EMT activation in the absence of cell death. Furthermore, results suggest that high-resolution metabolomics could serve as a powerful tool to investigate metal toxicity at levels which do not cause cell death.

Controllers of histone methylation-modifying enzymes in gastrointestinal cancers

Gastrointestinal (GI) cancers have been considered primarily genetic malignancies, caused by a series of progressive genetic alterations. Accumulating evidence shows that histone methylation, an epigenetic modification program, plays an essential role in the different pathological stages of GI cancer progression, such as precancerous lesions, tumorigenesis, and tumor metastasis. Histone methylation-modifying enzymes, including histone methyltransferases (HMTs) and demethylases (HDMs), are the main executor of post-transcriptional modification. The abnormal expression of histone methylation-modifying enzymes characterizes GI cancers with complex pathogenesis and progression. Interactions between upstream controllers and histone methylation-modifying enzymes have recently been revealed, and have provided numerous opportunities to elucidate the pathogenesis of GI cancers in depth and clearly. Here we focus on the association between histone methylation-modifying enzymes and their controllers, aiming to provide a new perspective on the molecular research and clinical management of GI cancers.

Overexpression of Fatty Acid Synthase Upregulates Glutamine-Fructose-6-Phosphate Transaminase 1 and O-Linked N-Acetylglucosamine Transferase to Increase O-GlcNAc Protein Glycosylation and Promote Colorectal Cancer Growth

Fatty acid synthesis has been extensively investigated as a therapeutic target in cancers, including colorectal cancer (CRC). Fatty acid synthase (FASN), a key enzyme of de novo lipid synthesis, is significantly upregulated in CRC, and therapeutic approaches of targeting this enzyme are currently being tested in multiple clinical trials. However, the mechanisms behind the pro-oncogenic action of FASN are still not completely understood. Here, for the first time, we show that overexpression of FASN increases the expression of glutamine-fructose-6-phosphate transaminase 1 (GFPT1) and O-linked N-acetylglucosamine transferase (OGT), enzymes involved in hexosamine metabolism, and the level of O-GlcNAcylation in vitro and in vivo. Consistently, expression of FASN significantly correlates with expression of GFPT1 and OGT in human CRC tissues. shRNA-mediated downregulation of GFPT1 and OGT inhibits cellular proliferation and the level of protein O-GlcNAcylation in vitro, and knockdown of GFPT1 leads to a significant decrease in tumor growth and metastasis in vivo. Pharmacological inhibition of GFPT1 and OGT leads to significant inhibition of cellular proliferation and colony formation in CRC cells. In summary, our results show that overexpression of FASN increases the expression of GFPT1 and OGT as well as the level of protein O-GlcNAcylation to promote progression of CRC; targeting the hexosamine biosynthesis pathway could be a therapeutic approach for this disease.

NMR Metabolomics of Primary Ovarian Cancer Cells in Comparison to Established Cisplatin-Resistant and -Sensitive Cell Lines

Cancer cell lines are frequently used in metabolomics, such as in vitro tumor models. In particular, A2780 cells are commonly used as a model for ovarian cancer to evaluate the effects of drug treatment. Here, we compare the NMR metabolomics profiles of A2780 and cisplatin-resistant A2780 cells with those of cells derived from 10 patients with high-grade serous ovarian carcinoma (collected during primary cytoreduction before any chemotherapeutic treatment). Our analysis reveals a substantial similarity among all primary cells but significant differences between them and both A2780 and cisplatin-resistant A2780 cells. Notably, the patient-derived cells are closer to the resistant A2780 cells when considering the exo-metabolome, whereas they are essentially equidistant from A2780 and A2780-resistant cells in terms of the endo-metabolome. This behavior results from dissimilarities in the levels of several metabolites attributable to the differential modulation of underlying biochemical pathways. The patient-derived cells are those with the most pronounced glycolytic phenotype, whereas A2780-resistant cells mainly diverge from the others due to alterations in a few specific metabolites already known as markers of resistance.

Phosphocholine-induced energy source shift alleviates mitochondrial dysfunction in lung cells caused by geospecific PM2.5 components

Fine particulate matter (PM2.5) is globally recognized for its adverse implications on human health. Yet, remain limited the individual contribution of particular PM2.5 components to its toxicity, especially considering regional disparities. Moreover, prevention solutions for PM2.5-associated health effects are scarce. In the present study, we comprehensively characterized and compared the primary PM2.5 constituents and their altered metabolites from two locations: Taiyuan and Guangzhou. Analysis of year-long PM2.5 samples revealed 84 major components, encompassing organic carbon, elemental carbon, ions, metals, and organic chemicals. PM2.5 from Taiyuan exhibited higher contamination, associated health risks, dithiothreitol activity, and cytotoxicities than Guangzhou's counterpart. Applying metabolomics, BEAS-2B lung cells exposed to PM2.5 from both cities were screened for significant alterations. A correlation analysis revealed the metabolites altered by PM2.5 and the critical toxic PM2.5 components in both regions. Among the PM2.5-down-regulated metabolites, phosphocholine emerged as a promising intervention for PM2.5 cytotoxicities. Its supplementation effectively attenuated PM2.5-induced energy metabolism disorder and cell death via activating fatty acid oxidation and inhibiting Phospho1 expression. The highlighted toxic chemicals displayed combined toxicities, potentially counteracted by phosphocholine. Our study offered a promising functional metabolite to alleviate PM2.5-induced cellular disorder and provided insights into the geo-based variability in toxic PM2.5 components.

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

Medical Relevance, State-of-the-Art and Perspectives of "Sweet Metacode" in Liquid Biopsy Approaches

This review briefly introduces readers to an area where glycomics meets modern oncodiagnostics with a focus on the analysis of sialic acid (Neu5Ac)-terminated structures. We present the biochemical perspective of aberrant sialylation during tumourigenesis and its significance, as well as an analytical perspective on the detection of these structures using different approaches for diagnostic and therapeutic purposes. We also provide a comparison to other established liquid biopsy approaches, and we mathematically define an early-stage cancer based on the overall prognosis and effect of these approaches on the patient's quality of life. Finally, some barriers including regulations and quality of clinical validations data are discussed, and a perspective and major challenges in this area are summarised.

Targeting Fatty Acid Desaturase I Inhibits Renal Cancer Growth Via ATF3-mediated ER Stress Response

Monounsaturated fatty acids (MUFAs) play a pivotal role in maintaining endoplasmic reticulum (ER) homeostasis, an emerging hallmark of cancer. However, the role of polyunsaturated fatty acid (PUFAs) desaturation in persistent ER stress driven by oncogenic abnormalities remains elusive. Fatty Acid Desaturase 1 (FADS1) is a rate-limiting enzyme controlling the bioproduction of long-chain PUFAs. Our previous research has demonstrated the significant role of FADS1 in cancer survival, especially in kidney cancers. We explored the underlying mechanism in this study. We found that pharmacological inhibition or knockdown of the expression of FADS1 effectively inhibits renal cancer cell proliferation and induces cell cycle arrest. The stable knockdown of FADS1 also significantly inhibits tumor formation in vivo. Mechanistically, we show that while FADS1 inhibition induces ER stress, its expression is also augmented by ER-stress inducers. Notably, FADS1-inhibition sensitized cellular response to ER stress inducers, providing evidence of FADS1's role in modulating the ER stress response in cancer cells. We show that, while FADS1 inhibition-induced ER stress leads to activation of ATF3, ATF3-knockdown rescues the FADS1 inhibition-induced ER stress and cell growth suppression. In addition, FADS1 inhibition results in the impaired biosynthesis of nucleotides and decreases the level of UPD-N-Acetylglucosamine, a critical mediator of the unfolded protein response. Our findings suggest that PUFA desaturation is crucial for rescuing cancer cells from persistent ER stress, supporting FADS1 as a new therapeutic target.

Metabolic challengers selecting tumor-persistent cells

Resistance to anticancer therapy still represents one of the main obstacles to cancer treatment. Numerous components of the tumor microenvironment (TME) contribute significantly to the acquisition of drug resistance. Microenvironmental pressures arising during cancer evolution foster tumor heterogeneity (TH) and facilitate the emergence of drug-resistant clones. In particular, metabolic pressures arising in the TME may favor epigenetic adaptations supporting the acquisition of persistence features in tumor cells. Tumor-persistent cells (TPCs) are characterized by high phenotypic and metabolic plasticity, representing a noticeable advantage in chemo- and radio-resistance. Understanding the crosslink between the evolution of metabolic pressures in the TME, epigenetics, and TPC evolution is significant for developing novel therapeutic strategies specifically targeting TPC vulnerabilities to overcome drug resistance.

Thyroid cancer cell metabolism: A glance into cell culture system-based metabolomics approaches

Thyroid cancer is the most common malignancy of the endocrine system and the seventh most prevalent cancer in women worldwide. It is a complex and diverse disease characterized by heterogeneity, underscoring the importance of understanding the underlying metabolic alterations within tumor cells. Metabolomics technologies offer a powerful toolset to explore and identify endogenous and exogenous biochemical reaction products, providing crucial insights into the intricate metabolic pathways and processes within living cells. Metabolism plays a central role in cell function, making metabolomics a valuable reflection of a cell's phenotype. In the OMICs era, metabolomics analysis of cells brings numerous advantages over existing methods, propelling cell metabolomics as an emerging field with vast potential for investigating metabolic pathways and their perturbation in pathophysiological conditions. This review article aims to look into recent developments in applying metabolomics for characterizing and interpreting the cellular metabolome in thyroid cancer cell lines, exploring their unique metabolic characteristics. Understanding the metabolic alterations in tumor cells can lead to the identification of critical nodes in the metabolic network that could be targeted for therapeutic intervention.

Developmental regulation of cellular metabolism is required for intestinal elongation and rotation

Malrotation of the intestine is a prevalent birth anomaly, the etiology of which remains poorly understood. Here, we show that late-stage exposure of Xenopus embryos to atrazine, a widely used herbicide that targets electron transport chain (ETC) reactions, elicits intestinal malrotation at high frequency. Interestingly, atrazine specifically inhibits the cellular morphogenetic events required for gut tube elongation, including cell rearrangement, differentiation and proliferation; insufficient gut lengthening consequently reorients the direction of intestine rotation. Transcriptome analyses of atrazine-exposed intestines reveal misexpression of genes associated with glycolysis and oxidative stress, and metabolomics shows that atrazine depletes key glycolytic and tricarboxylic acid cycle metabolites. Moreover, cellular bioenergetics assays indicate that atrazine blocks a crucial developmental transition from glycolytic ATP production toward oxidative phosphorylation. Atrazine-induced defects are phenocopied by rotenone, a known ETC Complex I inhibitor, accompanied by elevated reactive oxygen species, and rescued by antioxidant supplementation, suggesting that malrotation may be at least partly attributable to redox imbalance. These studies reveal roles for metabolism in gut morphogenesis and implicate defective gut tube elongation and/or metabolic perturbations in the etiology of intestinal malrotation.

Purine Metabolism and Hexosamine Biosynthetic Pathway Abnormalities in Diarrheal Weaned Piglets Identified Using Metabolomics

Post-weaning diarrhea significantly contributes to the high mortality in pig production, but the metabolic changes in weaned piglets with diarrhea remain unclear. This study aimed to identify the differential metabolites in the urine of diarrheal weaned piglets and those of healthy weaned piglets to reveal the metabolic changes associated with diarrhea in weaned piglets. Nine 25-day-old piglets with diarrhea scores above 16 and an average body weight of 5.41 ± 0.18 kg were selected for the diarrhea group. Corresponding to the body weight and sex of the diarrhea group, nine 25-month-old healthy piglets with similar sex and body weights of 5.49 ± 0.21 kg were selected as the control group. Results showed that the serum C-reactive protein and cortisol of piglets in the diarrhea group were higher than those in the control group (p < 0.05). The mRNA expression of TNF-α, IFN-γ in the jejunum and colon, and IL-1β in the jejunum were increased in diarrhea piglets (p < 0.05), accompanied by a reduction in the mRNA expression of ZO-1, ZO-2, and CLDN1 in the jejunum and colon (p < 0.05); mRNA expression of OCLN in the colon also occurred (p < 0.05). Metabolomic analysis of urine revealed increased levels of inosine, hypoxanthine, guanosine, deoxyinosin, glucosamine, glucosamine-1-p, N-Acetylmannosamine, chitobiose, and uric acid, identified as differential metabolites in diarrhea piglets compared to the controls. In summary, elevated weaning stress and inflammatory disease were associated with the abnormalities of purine metabolism and the hexosamine biosynthetic pathway of weaned piglets. This study additionally indicated the presence of energy metabolism-related diseases in diarrheal weaned piglets.

Diet-inducing hypercholesterolemia show decreased O-GlcNAcylation of liver proteins through modulation of AMPK

O-GlcNAcylation, a nutritionally driven, post-translational modification of proteins, is gaining importance because of its health implications. Changes in O-GlcNAcylation are observed in various disease conditions. Changes in O-GlcNAcylation by diet that causes hypercholesterolemia are not critically looked into in the liver. To address it, both in vitro and in vivo approaches were employed. Hypercholesterolemia was induced individually by feeding cholesterol (H)/high-fat (HF) diet. Global O-GlcNAcylation levels and modulation of AMPK activation in both preventive and curative approaches were looked into. Diet-induced hypercholesterolemia resulted in decreased O-GlcNAcylation of liver proteins which was associated with decreased O-linked N-acetylglucosaminyltransferase (OGT) and Glutamine fructose-6-phosphate amidotransferase-1 (GFAT1). Activation of AMPK by metformin in preventive mode restored the O-GlcNAcylation levels; however, metformin treatment of HepG2 cells in curative mode restored O-GlcNAcylation levels in HF but failed to in H condition (at 24 h). Further, maternal faulty diet resulted in decreased O-GlcNAcylation in pup liver despite feeding normal diet till adulthood. A faulty diet modulates global O-GlcNAcylation of liver proteins which is accompanied by decreased AMPK activation which could exacerbate metabolic syndromes through fat accumulation in the liver.

Amino sugars influence Aspergillus fumigatus cell wall polysaccharide biosynthesis, and biofilm formation through interfering galactosaminogalactan deacetylation

Aspergillus fumigatus is a ubiquitous fungal pathogen responsible for a significant number of deaths annually due to invasive aspergillosis infection. While the utilization of diverse carbon sources, including amino sugars, has been explored in other fungi, its impact on A. fumigatus remains uncharted territory. In this study, we investigated A. fumigatus responses to glucose (Glc), glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) as carbon sources. GlcN inhibited growth, reduced sporulation and delayed germination, while GlcNAc had no such effects. Both amino sugars induced alterations in cell wall composition, leading to a reduction in glucan and galactomannan levels while increasing chitin and mannan content, rendering A. fumigatus susceptible to cell wall stress and osmotic stress. GlcN repressed biofilm formation via downregulation of galactosaminogalactan (GAG) cluster genes, notably agd3, which encodes a GAG-specific deacetylase. Moreover, GlcN increased biofilm susceptibility to echinocandins, suggesting its potential for enhancing the effectiveness of antifungal treatments. This study sheds light on the multifaceted effects of amino sugars on A. fumigatus, encompassing growth, cell wall biosynthesis, and biofilm formation, offering promising avenues for innovative aspergillosis treatment strategies.

Nutrient inputs and social metabolic control of T cell fate

Cells in multicellular organisms experience diverse neighbors, signals, and evolving physical environments that drive functional and metabolic demands. To maintain proper development and homeostasis while avoiding inappropriate cell proliferation or death, individual cells interact with their neighbors via "social" cues to share and partition available nutrients. Metabolic signals also contribute to cell fate by providing biochemical links between cell-extrinsic signals and available resources. In addition to metabolic checkpoints that sense nutrients and directly supply molecular intermediates for biosynthetic pathways, many metabolites directly signal or provide the basis for post-translational modifications of target proteins and chromatin. In this review, we survey the landscape of T cell nutrient sensing and metabolic signaling that supports proper immunity while avoiding immunodeficiency or autoimmunity. The integration of cell-extrinsic microenvironmental cues with cell-intrinsic metabolic signaling provides a social metabolic control model to integrate cell signaling, metabolism, and fate.

Direct stimulation of de novo nucleotide synthesis by O-GlcNAcylation

O-linked β-N-acetyl glucosamine (O-GlcNAc) is at the crossroads of cellular metabolism, including glucose and glutamine; its dysregulation leads to molecular and pathological alterations that cause diseases. Here we report that O-GlcNAc directly regulates de novo nucleotide synthesis and nicotinamide adenine dinucleotide (NAD) production upon abnormal metabolic states. Phosphoribosyl pyrophosphate synthetase 1 (PRPS1), the key enzyme of the de novo nucleotide synthesis pathway, is O-GlcNAcylated by O-GlcNAc transferase (OGT), which triggers PRPS1 hexamer formation and relieves nucleotide product-mediated feedback inhibition, thereby boosting PRPS1 activity. PRPS1 O-GlcNAcylation blocked AMPK binding and inhibited AMPK-mediated PRPS1 phosphorylation. OGT still regulates PRPS1 activity in AMPK-deficient cells. Elevated PRPS1 O-GlcNAcylation promotes tumorigenesis and confers resistance to chemoradiotherapy in lung cancer. Furthermore, Arts-syndrome-associated PRPS1 R196W mutant exhibits decreased PRPS1 O-GlcNAcylation and activity. Together, our findings establish a direct connection among O-GlcNAc signals, de novo nucleotide synthesis and human diseases, including cancer and Arts syndrome.

The role of glycosylation in clinical allergy and immunology

While glycans are among the most abundant macromolecules on the cell with widespread functions, their role in immunity has historically been challenging to study. This is in part due to difficulties assimilating glycan analysis into routine approaches used to interrogate immune cell function. Despite this, recent developments have illuminated fundamental roles for glycans in host immunity. The growing field of glycoimmunology continues to leverage new tools and approaches to uncover the function of glycans and glycan-binding proteins in immunity. Here we utilize clinical vignettes to examine key roles of glycosylation in allergy, inborn errors of immunity, and autoimmunity. We will discuss the diverse functions of glycans as epitopes, as modulators of antibody function, and as regulators of immune cell function. Finally, we will highlight immune modulatory therapies that harness the critical role of glycans in the immune system.

The intersection of HIF-1α, O-GlcNAc, and skeletal muscle loss in chronic obstructive pulmonary disease

Sarcopenia, defined as the loss of muscle mass and strength, is a major cause of morbidity and mortality in COPD (chronic obstructive pulmonary disease) patients. However, the molecular mechanisms that cause sarcopenia remain to be determined. In this review, we will highlight the unique molecular and metabolic perturbations that occur in the skeletal muscle of COPD patients in response to hypoxia, and emphasize important areas of future research. In particular, the mechanisms related to the glycolytic shift that occurs in skeletal muscle in response to hypoxia may occur via a hypoxia-inducible factor 1-alpha (HIF-1α)-mediated mechanism. Upregulated glycolysis in skeletal muscle promotes a unique post-translational glycosylation of proteins known as O-GlcNAcylation, which further shifts metabolism toward glycolysis. Molecular changes in the skeletal muscle of COPD patients are associated with fiber-type shifting from Type I (oxidative) muscle fibers to Type II (glycolytic) muscle fibers. The metabolic shift toward glycolysis caused by HIF-1α and O-GlcNAc modified proteins suggests a potential cause for sarcopenia in COPD, which is an emerging area of future research.

Molecular Mechanisms Linking Diabetes with Increased Risk of Thrombosis

This review will provide an overview of what is currently known about mechanisms linking poor glycaemic control with increased thrombotic risk. The leading causes of death in people with diabetes are strokes and cardiovascular disease. Significant morbidity is associated with an increased risk of thrombosis, resulting in myocardial infarction, ischaemic stroke, and peripheral vascular disease, along with the sequelae of these events, including loss of functional ability, heart failure, and amputations. While the increased platelet activity, pro-coagulability, and endothelial dysfunction directly impact this risk, the molecular mechanisms linking poor glycaemic control with increased thrombotic risk remain unclear. This review highlights the complex mechanisms underlying thrombosis prevalence in individuals with diabetes and hyperglycaemia. Post-translational modifications, such as O-GlcNAcylation, play a crucial role in controlling protein function in diabetes. However, the role of O-GlcNAcylation remains poorly understood due to its intricate regulation and the potential involvement of multiple variables. Further research is needed to determine the precise impact of O-GlcNAcylation on specific disease processes.

Cardioprotective O-GlcNAc signaling is elevated in murine female hearts via enhanced O-GlcNAc transferase activity

The post-translational modification of intracellular proteins by O-linked β-GlcNAc (O-GlcNAc) has emerged as a critical regulator of cardiac function. Enhanced O-GlcNAcylation activates cytoprotective pathways in cardiac models of ischemia-reperfusion (I/R) injury; however, the mechanisms underpinning O-GlcNAc cycling in response to I/R injury have not been comprehensively assessed. The cycling of O-GlcNAc is regulated by the collective efforts of two enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), which catalyze the addition and hydrolysis of O-GlcNAc, respectively. It has previously been shown that baseline heart physiology and pathophysiology are impacted by sex. Here, we hypothesized that sex differences in molecular signaling may target protein O-GlcNAcylation both basally and in ischemic hearts. To address this question, we subjected male and female WT murine hearts to ex vivo ischemia or I/R injury. We assessed hearts for protein O-GlcNAcylation, abundance of OGT, OGA, and glutamine:fructose-6-phosphate aminotransferase (GFAT2), activity of OGT and OGA, and UDP-GlcNAc levels. Our data demonstrate elevated O-GlcNAcylation in female hearts both basally and during ischemia. We show that OGT activity was enhanced in female hearts in all treatments, suggesting a mechanism for these observations. Furthermore, we found that ischemia led to reduced O-GlcNAcylation and OGT-specific activity. Our findings provide a foundation for understanding molecular mechanisms that regulate O-GlcNAcylation in the heart and highlight the importance of sex as a significant factor when assessing key regulatory events that control O-GlcNAc cycling. These data suggest the intriguing possibility that elevated O-GlcNAcylation in females contributes to reduced ischemic susceptibility.

O-GlcNAcylation regulates OTX2's proteostasis

O-GlcNAcylation is a key post-translational modification, playing a vital role in cell signaling during development, especially in the brain. In this study, we investigated the role of O-GlcNAcylation in regulating the homeobox protein OTX2, which contributes to various brain disorders, such as combined pituitary hormone deficiency, retinopathy, and medulloblastoma. Our research demonstrated that, under normal physiological conditions, the proteasome plays a pivotal role in breaking down endogenous OTX2. However, when the levels of OTX2 rise, it forms oligomers and/or aggregates that require macroautophagy for clearance. Intriguingly, we demonstrated that O-GlcNAcylation enhances the solubility of OTX2, thereby limiting the formation of these aggregates. Additionally, we unveiled an interaction between OTX2 and the chaperone protein CCT5 at the O-GlcNAc sites, suggesting a potential collaborative role in preventing OTX2 aggregation. Finally, our study demonstrated that while OTX2 physiologically promotes cell proliferation, an O-GlcNAc-depleted OTX2 is detrimental to cancer cells.

Repeated sleep deprivation decreases the flux into hexosamine biosynthetic pathway/O-GlcNAc cycling and aggravates Alzheimer's disease neuropathology in adult zebrafish

This study investigated chronic and repeated sleep deprivation (RSD)-induced neuronal changes in hexosamine biosynthetic pathway/O-linked N-acetylglucosamine (HBP/O-GlcNAc) cycling of glucose metabolism and further explored the role of altered O-GlcNAc cycling in promoting neurodegeneration using an adult zebrafish model. RSD-triggered degenerative changes in the brain led to impairment of memory, neuroinflammation and amyloid beta (Aβ) accumulation. Metabolite profiling of RSD zebrafish brain revealed a significant decrease in glucose, indicating a potential association between RSD-induced neurodegeneration and dysregulated glucose metabolism. While RSD had no impact on overall O-GlcNAcylation levels in the hippocampus region, changes were observed in two O-GlcNAcylation-regulating enzymes, specifically, a decrease in O-GlcNAc transferase (OGT) and an increase in O-GlcNAcase (OGA). Glucosamine (GlcN) treatment induced an increase in O-GlcNAcylation and recovery of the OGT level that was decreased in the RSD group. In addition, GlcN reversed cognitive impairment by RSD. GlcN reduced neuroinflammation and attenuated Aβ accumulation induced by RSD. Repeated treatment of zebrafish with diazo-5-oxo-l-norleucine (DON), an inhibitor of HBP metabolism, resulted in cognitive dysfunction, neuroinflammation and Aβ accumulation, similar to the effects of RSD. The pathological changes induced by DON were restored to normal upon treatment with GlcN. Both the SD and DON-treated groups exhibited a common decrease in glutamate and γ-aminobutyric acid compared to the control group. Overexpression of OGT in zebrafish brain rescued RSD-induced neuronal dysfunction and neurodegeneration. RSD induced a decrease in O-GlcNAcylation of amyloid precursor protein and increase in β-secretase activity, which were reversed by GlcN treatment. Based on the collective findings, we propose that dysregulation of HBP and O-GlcNAc cycling in brain plays a crucial role in RSD-mediated progression of neurodegeneration and Alzheimer's disease pathogenesis. Targeting of this pathway may, therefore, offer an effective regulatory approach for treatment of sleep-associated neurodegenerative disorders.

High dietary fructose promotes hepatocellular carcinoma progression by enhancing O-GlcNAcylation via microbiota-derived acetate

Emerging studies have addressed the tumor-promoting role of fructose in different cancers. The effects and pathological mechanisms of high dietary fructose on hepatocellular carcinoma (HCC) remain unclear. Here, we examined the effects of fructose supplementation on HCC progression in wild-type C57BL/6 mice using a spontaneous and chemically induced HCC mouse model. We show that elevated uridine diphospho-N-acetylglucosamine (UDP-GlcNAc) and O-GlcNAcylation levels induced by high dietary fructose contribute to HCC progression. Non-targeted metabolomics and stable isotope tracing revealed that under fructose treatment, microbiota-derived acetate upregulates glutamine and UDP-GlcNAc levels and enhances protein O-GlcNAcylation in HCC. Global profiling of O-GlcNAcylation revealed that hyper-O-GlcNAcylation of eukaryotic elongation factor 1A1 promotes cell proliferation and tumor growth. Targeting glutamate-ammonia ligase or O-linked N-acetylglucosamine transferase (OGT) remarkably impeded HCC progression in mice with high fructose intake. We propose that high dietary fructose promotes HCC progression through microbial acetate-induced hyper-O-GlcNAcylation.

H3K4me3 remodeling induced acquired resistance through O-GlcNAc transferase

AIMS

Drivers of the drug tolerant proliferative persister (DTPP) state have not been well investigated. Histone H3 lysine-4 trimethylation (H3K4me3), an active histone mark, might enable slow cycling drug tolerant persisters (DTP) to regain proliferative capacity. This study aimed to determine H3K4me3 transcriptionally active sites identifying a key regulator of DTPPs.

METHODS

Deploying a model of adaptive cancer drug tolerance, H3K4me3 ChIP-Seq data of DTPPs guided identification of top transcription factor binding motifs. These suggested involvement of O-linked N-acetylglucosamine transferase (OGT), which was confirmed by metabolomics analysis and biochemical assays. OGT impact on DTPPs and adaptive resistance was explored in vitro and in vivo.

RESULTS

H3K4me3 remodeling was widespread in CPG island regions and DNA binding motifs associated with O-GlcNAc marked chromatin. Accordingly, we observed an upregulation of OGT, O-GlcNAc and its binding partner TET1 in chronically treated cancer cells. Inhibition of OGT led to loss of H3K4me3 and downregulation of genes contributing to drug resistance. Genetic ablation of OGT prevented acquired drug resistance in in vivo models. Upstream of OGT, we identified AMPK as an actionable target. AMPK activation by acetyl salicylic acid downregulated OGT with similar effects on delaying acquired resistance.

CONCLUSION

Our findings uncover a fundamental mechanism of adaptive drug resistance that governs cancer cell reprogramming towards acquired drug resistance, a process that can be exploited to improve response duration and patient outcomes.

The role of endoplasmic reticulum stress in promoting aerobic glycolysis in cancer cells: An overview

Aerobic glycolysis, also known as the Warburg effect, is a metabolic phenomenon frequently observed in cancer cells, characterized by the preferential utilization of glucose through glycolysis, even under normal oxygen conditions. This metabolic shift provides cancer cells with a proliferative advantage and supports their survival and growth. While the Warburg effect has been extensively studied, the underlying mechanisms driving this metabolic adaptation in cancer cells remain incompletely understood. In recent years, emerging evidence has suggested a potential link between endoplasmic reticulum (ER) stress and the promotion of aerobic glycolysis in cancer cells. The ER is a vital organelle involved in protein folding, calcium homeostasis, and lipid synthesis. Various cellular stresses, such as hypoxia, nutrient deprivation, and accumulation of misfolded proteins, can lead to ER stress. In response, cells activate the unfolded protein response (UPR) to restore ER homeostasis. However, prolonged or severe ER stress can activate alternative signaling pathways that modulate cellular metabolism, including the promotion of aerobic glycolysis. This review aims to provide an overview of the current understanding regarding the influence of ER stress on aerobic glycolysis in cancer cells to shed light on the complex interplay between ER stress and metabolic alterations in cancer cells. Understanding the intricate relationship between ER stress and the promotion of aerobic glycolysis in cancer cells may provide valuable insights for developing novel therapeutic strategies targeting metabolic vulnerabilities in cancer.

On a sugar high: Role of O-GlcNAcylation in cancer

Recent advances in the understanding of the molecular mechanisms underlying cancer progression have led to the development of novel therapeutic targeting strategies. Aberrant glycosylation patterns and their implication in cancer have gained increasing attention as potential targets due to the critical role of glycosylation in regulating tumor-specific pathways that contribute to cancer cell survival, proliferation, and progression. A special type of glycosylation that has been gaining momentum in cancer research is the modification of nuclear, cytoplasmic, and mitochondrial proteins, termed O-GlcNAcylation. This protein modification is catalyzed by an enzyme called O-GlcNAc transferase (OGT), which uses the final product of the Hexosamine Biosynthetic Pathway (HBP) to connect altered nutrient availability to changes in cellular signaling that contribute to multiple aspects of tumor progression. Both O-GlcNAc and its enzyme OGT are highly elevated in cancer and fulfill the crucial role in regulating many hallmarks of cancer. In this review, we present and discuss the latest findings elucidating the involvement of OGT and O-GlcNAc in cancer.

Hyaluronic acid: More than a carrier, having an overpowering extracellular and intracellular impact on cancer

Hyaluronic acid (HA), also named hyaluronan, is an omnipresent component of the tissue microenvironment. It is extensively used to formulate targeted drug delivery systems for cancer. Although HA itself has pivotal influences in various cancers, its calibers are somewhat neglected when using it as delivering platform to treat cancer. In the last decade, multiple studies revealed roles of HA in cancer cell proliferation, invasion, apoptosis, and dormancy through pathways like mitogen-activated protein kinase-extracellular signal-regulated kinase (MAPK/ERK), P³⁸, and nuclear factor kappa-light chain-enhancer of activated B cells (NFκB). A more fascinating fact is that the distinct molecular weight (MW) of HA exerts disparate effects on the same type of cancer. Its overwhelming use in cancer therapy and other therapeutic products make collective research on the sundry impact of it on various types of cancer, an essential aspect to be considered in all of these domains. Even the development of new therapies against cancer needed meticulous studies on HA because of its divergence of activity based on MW. This review will provide painstaking insight into the extracellular and intracellular bioactivity of HA, its modified forms, and its MW in cancers, which may improve the management of cancer.

Mitochondrial Dynamics and Cristae Shape Changes During Metabolic Reprogramming

Significance: The architecture of the mitochondrial network and cristae critically impact cell differentiation and identity. Cells undergoing metabolic reprogramming to aerobic glycolysis (Warburg effect), such as immune cells, stem cells, and cancer cells, go through controlled modifications in mitochondrial architecture, which is critical for achieving the resulting cellular phenotype. Recent Advances: Recent studies in immunometabolism have shown that the manipulation of mitochondrial network dynamics and cristae shape directly affects T cell phenotype and macrophage polarization through altering energy metabolism. Similar manipulations also alter the specific metabolic phenotypes that accompany somatic reprogramming, stem cell differentiation, and cancer cells. The modulation of oxidative phosphorylation activity, accompanied by changes in metabolite signaling, reactive oxygen species generation, and adenosine triphosphate levels, is the shared underlying mechanism. Critical Issues: The plasticity of mitochondrial architecture is particularly vital for metabolic reprogramming. Consequently, failure to adapt the appropriate mitochondrial morphology often compromises the differentiation and identity of the cell. Immune, stem, and tumor cells exhibit striking similarities in their coordination of mitochondrial morphology with metabolic pathways. However, although many general unifying principles can be observed, their validity is not absolute, and the mechanistic links thus need to be further explored. Future Directions: Better knowledge of the molecular mechanisms involved and their relationships to both mitochondrial network and cristae morphology will not only further deepen our understanding of energy metabolism but may also contribute to improved therapeutic manipulation of cell viability, differentiation, proliferation, and identity in many different cell types. Antioxid. Redox Signal. 39, 684-707.

Understanding glycosylation: Regulation through the metabolic flux of precursor pathways

Glycosylation is how proteins and lipids are modified with complex carbohydrates known as glycans. The post-translational modification of proteins with glycans is not a template-driven process in the same way as genetic transcription or protein translation. Glycosylation is instead dynamically regulated by metabolic flux. This metabolic flux is determined by the concentrations and activities of the glycotransferase enzymes, which synthesise glycans, the metabolites that act as their precursors and transporter proteins. This review provides an overview of the metabolic pathways underlying glycan synthesis. Pathological dysregulation of glycosylation, particularly increased glycosylation occurring during inflammation, is also elucidated. The resulting inflammatory hyperglycosylation acts as a glycosignature of disease, and we report on the changes in the metabolic pathways which feed into glycan synthesis, revealing alterations to key enzymes. Finally, we examine studies in developing metabolic inhibitors targeting these critical enzymes. These results provide the tools for researchers investigating the role of glycan metabolism in inflammation and have helped to identify promising glycotherapeutic approaches to inflammation.

Inhibition of O-GlcNAcylation Reduces Cell Viability and Autophagy and Increases Sensitivity to Chemotherapeutic Temozolomide in Glioblastoma

Glioblastoma (GB) is the most aggressive primary malignant brain tumor and is associated with short survival. O-GlcNAcylation is an intracellular glycosylation that regulates protein function, enzymatic activity, protein stability, and subcellular localization. Aberrant O-GlcNAcylation is related to the tumorigenesis of different tumors, and mounting evidence supports O-GlcNAc transferase (OGT) as a potential therapeutic target. Here, we used two human GB cell lines alongside primary human astrocytes as a non-tumoral control to investigate the role of O-GlcNAcylation in cell proliferation, cell cycle, autophagy, and cell death. We observed that hyper O-GlcNAcylation promoted increased cellular proliferation, independent of alterations in the cell cycle, through the activation of autophagy. On the other hand, hypo O-GlcNAcylation inhibited autophagy, promoted cell death by apoptosis, and reduced cell proliferation. In addition, the decrease in O-GlcNAcylation sensitized GB cells to the chemotherapeutic temozolomide (TMZ) without affecting human astrocytes. Combined, these results indicated a role for O-GlcNAcylation in governing cell proliferation, autophagy, cell death, and TMZ response, thereby indicating possible therapeutic implications for treating GB. These findings pave the way for further research and the development of novel treatment approaches which may contribute to improved outcomes and increased survival rates for patients facing this challenging disease.