Augmented TME O-GlcNAcylation Promotes Tumor Proliferation through the Inhibition of p38 MAPK

Therapeutic potentials and targeting strategies of quercetin on cancer cells: Challenges and future prospects

BACKGROUND

Every cell in the human body is vital because it maintains equilibrium and carries out a variety of tasks, including growth and development. These activities are carried out by a set of instructions carried by many different genes and organized into DNA. It is well recognized that some lifestyle decisions, like using tobacco, alcohol, UV, or multiple sexual partners, might increase one's risk of developing cancer. The advantages of natural products for any health issue are well known, and researchers are making attempts to separate flavonoid-containing substances from plants. Various parts of plants contain a phenolic compound called flavonoid. Quercetin, which belongs to the class of compounds known as flavones with chromone skeletal structure, has anti-cancer activity.

PURPOSE

The study was aimed at investigating the therapeutic action of the flavonoid quercetin on various cancer cells.

METHODS

The phrases quercetin, anti-cancer, nanoparticles, and cell line were used to search the data using online resources such as PubMed, and Google Scholar. Several critical previous studies have been included.

RESULTS

Quercetin inhibits various dysregulated signaling pathways that cause cancer cells to undergo apoptosis to exercise its anticancer effects. Numerous signaling pathways are impacted by quercetin, such as the Hedgehog system, Akt, NF-κB pathway, downregulated mutant p53, JAK/STAT, G1 phase arrest, Wnt/β-Catenin, and MAPK. There are downsides to quercetin, like hydrophobicity, first-pass effect, instability in the gastrointestinal tract, etc., because of which it is not well-established in the pharmaceutical industry. The solution to these drawbacks in the future is using bio-nanomaterials like chitosan, PLGA, liposomes, and silk fibroin as carriers, which can enhance the target specificity of quercetin. The first section of this review covers the specifics of flavonoids and quercetin; the second section covers the anti-cancer activity of quercetin; and the third section explains the drawbacks and conjugation of quercetin with nanoparticles for drug delivery by overcoming quercetin's drawback.

CONCLUSIONS

Overall, this review presented details about quercetin, which is a plant derivative with a promising molecular mechanism of action. They inhibit cancer by various mechanisms with little or no side effects. It is anticipated that plant-based materials will become increasingly relevant in the treatment of cancer.

Glycans in melanoma: Drivers of tumour progression but sweet targets to exploit for immunotherapy

Aberrant glycosylation recently emerged as an unmissable hallmark of cancer progression in many cancers. In melanoma, there is growing evidence that the tumour 'glycocode' plays a major role in promoting cell proliferation, invasion, migration, but also dictates the nature of the immune infiltrate, which strongly affects immune cell function, and clinical outcome. Aberrant glycosylation patterns dismantle anti-tumour defence through interactions with lectins on immune cells, which are crucial to shape anti-tumour immunity but also to trigger immune evasion. The glycan/lectin axis represents a new immune subversion pathway that is exploited by melanoma to hijack immune cells and escape from immune control. In this review, we describe the glycosylation features of melanoma tumour cells, and further gather findings related to the role of glycosylation in melanoma tumour progression, deciphering in detail its impact on immunity. We also depict glycan-based strategies aiming at restoring a functional anti-tumour response in melanoma patients. Glycans/lectins emerge as key immune checkpoints with promising translational properties. Exploitation of these pathways could reshape potent anti-tumour immunity while impeding immunosuppressive circuits triggered by aberrant tumour glycosylation patterns, holding great promise for cancer therapy.

Role of O-GlcNAcylation in cancer biology

One of the general characteristics of cancer cells is the abnormal increase of O-GlcNAcylation. Recent studies have shown that it affects the basic functions of proteins and regulates multiple phenotypes of cancer cells through key signals and metabolic pathways. O-GlcNAcylation is a covalent linkage between the β-D-N-acetylglucosamine (GlcNAc) sugar and target protein. It interacts with many other types of post-translational modifications and works together in the whole process of cancer development. For example, it regulates cell activities such as cell signal transduction, transcription, cell division, metabolism and cytoskeleton regulation. In this review, we summarized the general concept of O-GlcNAcylation and its related role in the ten major tumor phenotypes.

Improving targeted small molecule drugs to overcome chemotherapy resistance

BACKGROUND

Conventional cancer treatments face the challenge of therapeutic resistance, which causes poor treatment outcomes. The use of combination therapies can improve treatment results in patients and is one of the solutions to overcome this challenge. Chemotherapy is one of the conventional treatments that, due to the non-targeted and lack of specificity in targeting cancer cells, can cause serious complications in the short and long-term for patients by damaging healthy cells. Also, the employment of a wide range of strategies for chemotherapy resistance by cancer cells, metastasis, and cancer recurrence create serious problems to achieve the desired results of chemotherapy. Accordingly, targeted therapies can be used as a combination treatment with chemotherapy to both cause less damage to healthy cells, which as a result, they reduce the side effects of chemotherapy, and by targeting the factors that cause therapeutic challenges, can improve the results of chemotherapy in patients.

RECENT FINDINGS

Small molecules are one of the main targeted therapies that can be used for diverse targets in cancer treatment due to their penetration ability and characteristics. However, small molecules in cancer treatment are facing obstacles that a better understanding of cancer biology, as well as the mechanisms and factors involved in chemotherapy resistance, can lead to the improvement of this type of major targeted therapy.

CONCLUSION

In this review article, at first, the challenges that lead to not achieving the desired results in chemotherapy and how cancer cells can be resistant to chemotherapy are examined, and at the end, research areas are suggested that more focusing on them, can lead to the improvement of the results of using targeted small molecules as an adjunctive treatment for chemotherapy in the conditions of chemotherapy resistance and metastasis of cancer cells.

O-GlcNAcylation: cellular physiology and therapeutic target for human diseases

O-linked-β-N-acetylglucosamine (O-GlcNAcylation) is a distinctive posttranslational protein modification involving the coordinated action of O-GlcNAc transferase and O-GlcNAcase, primarily targeting serine or threonine residues in various proteins. This modification impacts protein functionality, influencing stability, protein-protein interactions, and localization. Its interaction with other modifications such as phosphorylation and ubiquitination is becoming increasingly evident. Dysregulation of O-GlcNAcylation is associated with numerous human diseases, including diabetes, nervous system degeneration, and cancers. This review extensively explores the regulatory mechanisms of O-GlcNAcylation, its effects on cellular physiology, and its role in the pathogenesis of diseases. It examines the implications of aberrant O-GlcNAcylation in diabetes and tumorigenesis, highlighting novel insights into its potential role in cardiovascular diseases. The review also discusses the interplay of O-GlcNAcylation with other protein modifications and its impact on cell growth and metabolism. By synthesizing current research, this review elucidates the multifaceted roles of O-GlcNAcylation, providing a comprehensive reference for future studies. It underscores the potential of targeting the O-GlcNAcylation cycle in developing novel therapeutic strategies for various pathologies.

Augmented O-GlcNAcylation exacerbates right ventricular dysfunction and remodeling via enhancement of hypertrophy, mitophagy, and fibrosis in mice exposed to long-term intermittent hypoxia

Previously, we showed that augmented O-linked N-acetylglucosaminylation (O-GlcNAcylation) mitigates cardiac remodeling in O-GlcNAc transferase-transgenic (Ogt-Tg) mice exposed to acute (2-week) intermittent hypoxia (IH) by suppressing nuclear factor of activated T cells (NFAT) and nuclear factor kappa B (NF-κB) via the O-GlcNAcylation of glycogen synthase kinase 3 beta (GSK-3β) and NF-κB p65. Because this effect is time dependent, we exposed Ogt-Tg mice to IH for 4 weeks (IH4W) in the present study. O-GlcNAcylation was significantly enhanced in Ogt-Tg mice vs. wild-type (WT) mice exposed to normoxia and IH4W. Total O-GlcNAcylation levels were significantly increased in WT and Ogt-Tg mice after IH4W vs. normoxia. After IH4W, Ogt-Tg mice displayed significantly exacerbated signs of cardiac hypertrophy and fibrosis in the right ventricles (RVs) but not the left ventricles (LVs). Echocardiography revealed IH4W-induced right ventricular dysfunction. Phosphorylated GSK-3β levels were increased in Ogt-Tg mice vs. WT mice after IH4W, whereas phosphorylated NF-κB p65 levels were unaffected. Mitophagy, which is associated with cardiac dysfunction, was increased in the RVs of Ogt-Tg mice after IH4W. Furthermore, the levels of phosphorylated dynamin-related protein 1 (p-Drp1) were significantly increased, and the expression of mitofusin-2 (MFN2) was significantly decreased. In human embryonic kidney cells, mitochondrial uncoupler-induced mitochondrial dysfunction was accelerated in Ogt-overexpressing cells. In addition to increasing the levels of phosphorylated Smad2, IH4W promoted cardiac fibrosis in the RVs of Ogt-Tg mice. Thus, augmented O-GlcNAcylation may aggravate IH4W-induced right ventricular dysfunction and remodeling by promoting hypertrophy, mitophagy, and fibrosis via GSK-3β inactivation, an increased p-Drp-1/MFN2 ratio, and Smad2 activation, respectively.

O-GlcNAcylation-induced GSK-3β activation deteriorates pressure overload-induced heart failure via lack of compensatory cardiac hypertrophy in mice

O-GlcNAc transferase (OGT) modulates many functions of proteins via O-GlcNAcylation that adds O-linked β-N-acetylglucosamine (O-GlcNAc) to the serine/threonine residues of proteins. However, the role of O-GlcNAcylation in cardiac remodeling and function is not fully understood. To examine the effect of O-GlcNAcylation on pressure overload-induced cardiac hypertrophy and subsequent heart failure, transverse aortic constriction (TAC) surgery was performed in wild type (WT) and Ogt transgenic (Ogt-Tg) mice. Four weeks after TAC (TAC4W), the heart function of Ogt-Tg mice was significantly lower than that of WT mice (reduced fractional shortening and increased ANP levels). The myocardium of left ventricle (LV) in Ogt-Tg mice became much thinner than that in WT mice. Moreover, compared to the heart tissues of WT mice, O-GlcNAcylation of GSK-3β at Ser9 was increased and phosphorylation of GSK-3β at Ser9 was reduced in the heart tissues of Ogt-Tg mice, resulting in its activation and subsequent inactivation of nuclear factor of activated T cell (NFAT) activity. Finally, the thinned LV wall and reduced cardiac function induced by TAC4W in Ogt-Tg mice was reversed by the treatment of a GSK-3β inhibitor, TDZD-8. These results imply that augmented O-GlcNAcylation exacerbates pressure overload-induced heart failure due to a lack of compensatory cardiac hypertrophy via O-GlcNAcylation of GSK-3β, which deprives the phosphorylation site of GSK-3β to constantly inactivate NFAT activity to prevent cardiac hypertrophy. Our findings may provide a new therapeutic strategy for cardiac hypertrophy and subsequent heart failure.

Recent development of analytical methods for disease-specific protein O-GlcNAcylation

The enzymatic modification of protein serine or threonine residues by N-acetylglucosamine, namely O-GlcNAcylation, is a ubiquitous post-translational modification that frequently occurs in the nucleus and cytoplasm. O-GlcNAcylation is dynamically regulated by two enzymes, O-GlcNAc transferase and O-GlcNAcase, and regulates nearly all cellular processes in epigenetics, transcription, translation, cell division, metabolism, signal transduction and stress. Aberrant O-GlcNAcylation has been shown in a variety of diseases, including diabetes, neurodegenerative diseases and cancers. Deciphering O-GlcNAcylation remains a challenge due to its low abundance, low stoichiometry and extreme lability in most tandem mass spectrometry. Separation or enrichment of O-GlcNAc proteins or peptides from complex mixtures has been of great interest because quantitative analysis of protein O-GlcNAcylation can elucidate their functions and regulatory mechanisms in disease. However, valid and specific analytical methods are still lacking, and efforts are needed to further advance this direction. Here, we provide an overview of recent advances in various analytical methods, focusing on chemical oxidation, affinity of antibodies and lectins, hydrophilic interaction, and enzymatic addition of monosaccharides in conjugation with these methods. O-GlcNAcylation quantification has been described in detail using mass-spectrometric or non-mass-spectrometric techniques. We briefly summarized dysregulated changes in O-GlcNAcylation in disease.

RIG-I acts as a tumor suppressor in melanoma via regulating the activation of the MKK/p38MAPK signaling pathway

Studies have indicated that RIG-I may act as a tumor suppressor and participate in the tumorigenesis of some malignant diseases. However, RIG-I induces distinct cellular responses via different downstream signaling pathways depending on the cell type. To investigate the biological function and underlying molecular mechanism of RIG-I in the tumorigenesis of melanoma, we constructed RIG-I knockout, RIG-I-overexpressing B16-F10 and RIG-I knockdown A375 melanoma cell lines, and analyzed the RIG-I-mediated change in the biological behavior of tumor cells in spontaneous and poly (I:C)-induced RIG-I activation. Cell proliferation, cell cycling, apoptosis and migration were detected by CCK-8 assay, BrdU incorporation assay, Annexin V-PI staining assay and Transwell assay, respectively. In vivo tumorigenicity was evaluated by tumor xenograft growth in nude mice and subsequently by Ki67 staining and TUNEL assays. Furthermore, Western blotting was utilized to explore the underlying mechanism of RIG-I in melanoma cells. Our data showed that RIG-I promotes apoptosis and inhibits proliferation by G1 phase cell cycle arrest in the melanoma cell lines. Mechanistically, RIG-I induced the phosphorylation of p38 MAPK and MAPK kinases MKK3 and MKK4. In conclusion, the current study demonstrated that RIG-I suppressed the development of melanoma by regulating the activity of the MKK/p38 MAPK signaling pathway, which is relevant to research on novel therapeutic targets for this malignant disease.

O-GlcNAcylation regulation of cellular signaling in cancer

O-GlcNAcylation is a post-translational modification occurring on serine/threonine residues of nuclear and cytoplasmic proteins, mediated by the enzymes OGT and OGA which catalyze the addition or removal of the UDP-GlcNAc moieties, respectively. Structural changes brought by this modification lead to alternations of protein stability, protein-protein interactions, and phosphorylation. Importantly, O-GlcNAcylation is a nutrient sensor by coupling nutrient sensing with cellular signaling. Elevated levels of OGT and O-GlcNAc have been reported in a variety of cancers and has been linked to regulation of multiple cancer signaling pathways. In this review, we discuss the most recent findings on the role of O-GlcNAcylation as a metabolic sensor in signaling pathways and immune response in cancer.

STK10 knockout inhibits cell migration and promotes cell proliferation via modulating the activity of ERM and p38 MAPK in prostate cancer cells

Prostate cancer (PCa) is one of the most common types of cancer and is a serious threat to men's health due to the high rate of incidence and metastasis. However, the exact underlying pathology of this malignant disease has yet to be fully elucidated. The ezrin-radixin-moesin (ERM) family of proteins are associated with the development and metastasis of various types of cancer. Serine threonine kinase 10 (STK10) is an ERM kinase that is involved in the activation of ERM proteins and serves essential roles in the aggregation and adhesion of lymphocytes. To evaluate the functional roles of STK10 in the pathogenesis of PCa, a STK10-knockout (KO) DU145 PCa cell line was generated using the CRISPR-Cas9 gene editing system, and the effects of STK10 deletion on tumor biological behaviors were further analyzed. The present data suggested that STK10 KO promoted PCa cell proliferation by inhibiting p38 MAPK activation and suppressed migration primarily via the inhibition of p38 MAPK signaling and ERM protein activation. To the best of our knowledge, this is the first study to provide evidence that STK10 plays important roles in the proliferation and migration of PCa cells, which will be useful for further investigation into the pathogenesis of this disease.

Hedgehog signaling regulates metabolism and polarization of mammary tumor-associated macrophages

Elevated infiltration of immunosuppressive alternatively polarized (M2) macrophages is associated with poor prognosis in cancer patients. The tumor microenvironment remarkably orchestrates molecular mechanisms that program these macrophages. Here we identify a novel role for oncogenic Hedgehog (Hh) signaling in programming signature metabolic circuitries that regulate alternative polarization of tumor-associated macrophages. Two immunocompetent orthotopic mouse models of mammary tumors were used to test the effect of inhibiting Hh signaling on tumor-associated macrophages. Treatment with the pharmacological Hh inhibitor Vismodegib induced a significant shift in the profile of tumor-infiltrating macrophages. Mass spectrometry-based metabolomic analysis showed Hh inhibition induced significant alterations in metabolic processes, including metabolic sensing, mitochondrial adaptations, and lipid metabolism. In particular, inhibition of Hh in M2 macrophages reduced flux through the UDP-GlcNAc biosynthesis pathway. Consequently, O-GlcNAc-modification of STAT6 decreased, mitigating the immune suppressive program of M2 macrophages, and the metabolically demanding M2 macrophages shifted their metabolism and bioenergetics from fatty acid oxidation to glycolysis. M2 macrophages enriched from Vismodegib-treated mammary tumors showed characteristically decreased O-GlcNAcylation and altered mitochondrial dynamics. These Hh-inhibited macrophages are reminiscent of inflammatory (M1) macrophages, phenotypically characterized by fragmented mitochondria. This is the first report highlighting the relevance of Hh signaling in controlling a complex metabolic network in immune cells. These data describe a novel immunometabolic function of Hh signaling that can be clinically exploited.

O-GlcNAcylation is a key regulator of multiple cellular metabolic pathways

O-GlcNAcylation modifies proteins in serine or threonine residues in the nucleus, cytoplasm, and mitochondria. It regulates a variety of cellular biological processes and abnormal O-GlcNAcylation is associated with diabetes, cancer, cardiovascular disease, and neurodegenerative diseases. Recent evidence has suggested that O-GlcNAcylation acts as a nutrient sensor and signal integrator to regulate metabolic signaling, and that dysregulation of its metabolism may be an important indicator of pathogenesis in disease. Here, we review the literature focusing on O-GlcNAcylation regulation in major metabolic processes, such as glucose metabolism, mitochondrial oxidation, lipid metabolism, and amino acid metabolism. We discuss its role in physiological processes, such as cellular nutrient sensing and homeostasis maintenance. O-GlcNAcylation acts as a key regulator in multiple metabolic processes and pathways. Our review will provide a better understanding of how O-GlcNAcylation coordinates metabolism and integrates molecular networks.

MicroRNAs in Metastasis and the Tumour Microenvironment

Metastasis is the process whereby cancer cells migrate from the primary tumour site to colonise the surrounding or distant tissue or organ. Metastasis is the primary cause of cancer-related mortality and approximately half of all cancer patients present at diagnosis with some form of metastasis. Consequently, there is a clear need to better understand metastasis in order to develop new tools to combat this process. MicroRNAs (miRNAs) regulate gene expression and play an important role in cancer development and progression including in the metastatic process. Particularly important are the roles that miRNAs play in the interaction between tumour cells and non-tumoral cells of the tumour microenvironment (TME), a process mediated largely by circulating miRNAs contained primarily in extracellular vesicles (EVs). In this review, we outline the accumulating evidence for the importance of miRNAs in the communication between tumour cells and the cells of the TME in the context of the pre-metastatic and metastatic niche.

A sweet spot for macrophages: Focusing on polarization

Macrophages are a type of functionally plastic cells that can create a pro-/anti-inflammatory microenvironment for organs by producing different kinds of cytokines, chemokines, and growth factors to regulate immunity and inflammatory responses. In addition, they can also be induced to adopt different phenotypes in response to extracellular and intracellular signals, a process defined as M1/M2 polarization. Growing evidence indicates that glycobiology is closely associated with this polarization process. In this research, we review studies of the roles of glycosylation, glucose metabolism, and key lectins in the regulation of macrophages function and polarization to provide a new perspective for immunotherapies for multiple diseases.

Targeting the "Sweet Side" of Tumor with Glycan-Binding Molecules Conjugated-Nanoparticles: Implications in Cancer Therapy and Diagnosis

Nanotechnology is in the spotlight of therapeutic innovation, with numerous advantages for tumor visualization and eradication. The end goal of the therapeutic use of nanoparticles, however, remains distant due to the limitations of nanoparticles to target cancer tissue. The functionalization of nanosystem surfaces with biological ligands is a major strategy for directing the actions of nanomaterials specifically to tumor cells. Cancer formation and metastasis are accompanied by profound alterations in protein glycosylation. Hence, the detection and targeting of aberrant glycans are of great value in cancer diagnosis and therapy. In this review, we provide a brief update on recent progress targeting aberrant glycosylation by functionalizing nanoparticles with glycan-binding molecules (with a special focus on lectins and anti-glycan antibodies) to improve the efficacy of nanoparticles in cancer targeting, diagnosis, and therapy and outline the challenges and limitations in implementing this approach. We envision that the combination of nanotechnological strategies and cancer-associated glycan targeting could remodel the field of cancer diagnosis and therapy, including immunotherapy.

Pregnancy decreases O-GlcNAc-modified proteins in systemic arteries of normotensive and spontaneously hypertensive rats

AIM

We determined the role played by O-linked N-acetylglucosamine (O-GlcNAc) of proteins in systemic arteries during late pregnancy in normotensive and hypertensive rats.

MAIN METHODS

O-GlcNAc levels and O-GlcNAc modification of endothelial nitric oxide synthase (eNOS) were determined in aorta (conductance vessel) and mesenteric arteries (resistance vessels) of non-pregnant (NP) and pregnant (P) Wistar rats and spontaneously hypertensive rats (SHR). Vascular O-GlcNAc-modified proteins, O-GlcNAcase (OGA) and O-GlcNAc transferase (OGT) expression, and OGA activity were analyzed. Concentration-response to phenylephrine (PE) curves were constructed for arteries with and without endothelium. Arteries were treated with vehicle or PugNAc (OGA inhibitor, 100 μmol/L) in the presence of L-NAME (NOS inhibitor, 100 μmol/L).

KEY FINDINGS

The content of vascular O-GlcNAc-modified proteins was lower, OGT and OGA expression did not change, and OGA activity was higher in arteries of P-Wistar rats and P-SHR compared to arteries of NP-groups. Reactivity to PE increased in arteries of P-Wistar rats treated with PugNAc compared to vehicle. O-GlcNAcylation of eNOS decreased in P-SHR compared to NP-SHR. PugNAc partially inhibited the effects of endothelium removal and L-NAME on reactivity to PE in arteries of P-Wistar rats. However, PugNAc did not alter reactivity to PE in arteries of P-SHR. Our data showed that pregnancy decreased the content of vascular O-GlcNAc-modified proteins.

SIGNIFICANCE

Increased OGA activity and decreased O-GlcNAc modification of eNOS boosts eNOS activity in arteries of P-Wistar rats. In P-SHR, altered OGA activity may lower the content of O-GlcNAc-modified proteins, but decreased OGT activity seems a potential mechanism to reduce glycosylation.

Fluctuation in O-GlcNAcylation inactivates STIM1 to reduce store-operated calcium ion entry via down-regulation of Ser621 phosphorylation

Stromal interaction molecule 1 (STIM1) plays a pivotal role in store-operated Ca2+ entry (SOCE), an essential mechanism in cellular calcium signaling and in maintaining cellular calcium balance. Because O-GlcNAcylation plays pivotal roles in various cellular function, we examined the effect of fluctuation in STIM1 O-GlcNAcylation on SOCE activity. We found that both increase and decrease in STIM1 O-GlcNAcylation impaired SOCE activity. To determine the molecular basis, we established STIM1-knockout HEK293 (STIM1-KO-HEK) cells using the CRISPR/Cas9 system and transfected STIM1 WT (STIM1-KO-WT-HEK), S621A (STIM1-KO-S621A-HEK), or T626A (STIM1-KO-T626A-HEK) cells. Using these cells, we examined the possible O-GlcNAcylation sites of STIM1 to determine whether the sites were O-GlcNAcylated. Co-immunoprecipitation analysis revealed that Ser621 and Thr626 were O-GlcNAcylated and that Thr626 was O-GlcNAcylated in the steady state but Ser621 was not. The SOCE activity in STIM1-KO-S621A-HEK and STIM1-KO-T626A-HEK cells was lower than that in STIM1-KO-WT-HEK cells because of reduced phosphorylation at Ser621 Treatment with the O-GlcNAcase inhibitor Thiamet G or O-GlcNAc transferase (OGT) transfection, which increases O-GlcNAcylation, reduced SOCE activity, whereas treatment with the OGT inhibitor ST045849 or siOGT transfection, which decreases O-GlcNAcylation, also reduced SOCE activity. Decrease in SOCE activity due to increase and decrease in O-GlcNAcylation was attributable to reduced phosphorylation at Ser621 These data suggest that both decrease in O-GlcNAcylation at Thr626 and increase in O-GlcNAcylation at Ser621 in STIM1 lead to impairment of SOCE activity through decrease in Ser621 phosphorylation. Targeting STIM1 O-GlcNAcylation could provide a promising treatment option for the related diseases, such as neurodegenerative diseases.

Therapy-Induced Evolution of Human Lung Cancer Revealed by Single-Cell RNA Sequencing

Lung cancer, the leading cause of cancer mortality, exhibits heterogeneity that enables adaptability, limits therapeutic success, and remains incompletely understood. Single-cell RNA sequencing (scRNA-seq) of metastatic lung cancer was performed using 49 clinical biopsies obtained from 30 patients before and during targeted therapy. Over 20,000 cancer and tumor microenvironment (TME) single-cell profiles exposed a rich and dynamic tumor ecosystem. scRNA-seq of cancer cells illuminated targetable oncogenes beyond those detected clinically. Cancer cells surviving therapy as residual disease (RD) expressed an alveolar-regenerative cell signature suggesting a therapy-induced primitive cell-state transition, whereas those present at on-therapy progressive disease (PD) upregulated kynurenine, plasminogen, and gap-junction pathways. Active T-lymphocytes and decreased macrophages were present at RD and immunosuppressive cell states characterized PD. Biological features revealed by scRNA-seq were biomarkers of clinical outcomes in independent cohorts. This study highlights how therapy-induced adaptation of the multi-cellular ecosystem of metastatic cancer shapes clinical outcomes.

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scRNA-seq is feasible in metastatic human NSCLCs and reveals a rich tumor ecosystem

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Individual tumors and cancer cells exhibit substantial molecular diversity

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Cancer and tumor microenvironment cells exhibit marked therapy-induced plasticity

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scRNA-seq of metastatic NSCLCs unveils new opportunities to improve clinical outcomes

Hyperglycemia Enhances Cancer Immune Evasion by Inducing Alternative Macrophage Polarization through Increased O-GlcNAcylation

Diabetes mellitus (DM) significantly increases the risk for cancer and cancer progression. Hyperglycemia is the defining characteristic of DM and tightly correlates with a poor prognosis in patients with cancer. The hexosamine biosynthetic pathway (HBP) is emerging as a pivotal cascade linking high glucose, tumor progression, and impaired immune function. Here we show that enhanced glucose flow through the HBP drives cancer progression and immune evasion by increasing O-GlcNAcylation in tumor-associated macrophages (TAM). Increased O-GlcNAc skewed macrophage polarization to a M2-like phenotype supporting tumor progression. Finally, we found an upregulation of M2 markers on TAMs in DM2 patients with colorectal cancer compared with nondiabetic normoglycemic patients. Our results provide evidence for a new and targetable mechanism of cancer immune evasion in patients with hyperglycemia, advocating for strict control of hyperglycemia in patients with cancer.

Enhancement of O-linked N-acetylglucosamine modification promotes metastasis in patients with colorectal cancer and concurrent type 2 diabetes mellitus

Reversible post-translational modification of serine and threonine residues by O-linked N-acetylglucosamine (O-GlcNAc), termed O-GlcNAcylation has been indicated to regulate the activities of a number of different proteins. Augmented O-GlcNAcylation contributes to the etiologies of type 2 diabetes mellitus (T₂DM) and cancer. Moreover, diabetic conditions increase the risk of colorectal cancer. However, the effect of O-GlcNAcylation in patients with colorectal cancer and concurrent T₂DM has not been elucidated. The current study evaluated the level of O-GlcNAcylation in patients with colorectal cancer with or without T₂DM. Notably, O-GlcNAcylation levels were significantly higher in tissues from patients with T₂DM compared with those in patients without T₂DM, and higher in cancer tissues compared with corresponding adjacent tissues. O-GlcNAcylation and cancer stage were more strongly correlated in cancer tissues from patients with T₂DM compared with those from patients without T₂DM. Additionally, distant metastasis was significantly correlated with O-GlcNAcylation in cancer tissues from patients with T₂DM. β-catenin levels in colorectal cancer tissues were the highest in patients with advanced-stage cancer and concurrent T₂DM. In SW480 human colon cancer cells, thiamet G (TMG) treatment and OGA silencing, which increased O-GlcNAcylation, significantly increased β-catenin and SNAIL in high-glucose, but not during normal-glucose conditions. These data suggest that O-GlcNAcylation is closely associated with distant metastasis, most likely through upregulation of the β-catenin/SNAIL signaling pathway in colorectal cancer patients with T₂DM.

Exosomal miRNAs in tumor microenvironment

Tumor microenvironment (TME) is the internal environment in which tumor cells survive, consisting of tumor cells, fibroblasts, endothelial cells, and immune cells, as well as non-cellular components, such as exosomes and cytokines. Exosomes are tiny extracellular vesicles (40-160nm) containing active substances, such as proteins, lipids and nucleic acids. Exosomes carry biologically active miRNAs to shuttle between tumor cells and TME, thereby affecting tumor development. Tumor-derived exosomal miRNAs induce matrix reprogramming in TME, creating a microenvironment that is conducive to tumor growth, metastasis, immune escape and chemotherapy resistance. In this review, we updated the role of exosomal miRNAs in the process of TME reshaping.

Norcantharidin Enhances High Concentrations of Fetal Bovine Serum-Induced Apoptosis in Human Mesangial Cells by Regulating the Mitogen-Activated Protein Kinase Signaling Pathway

AIM

This study aimed to investigate the effect of norcantharidin (NCTD) on human mesangial cells (HMCs) apoptosis in vitro and further examine its molecular mechanism.

METHODS

HMCs were divided into 5 groups: control group, 25% fetal bovine serum (FBS)-treated group, and NCTD groups (NCTD [2.5, 5 and 10 µg/mL] + 25% FBS, respectively). Cell proliferation was determined by MTT assay, while apoptosis was evaluated by Hoechest 33258 staining, the level of cytochrome c, immunohistochemistry, and apoptotic-related proteins/gene expression.

RESULTS

Cell viability was inhibited in NCTD-treated HMCs in a dose-dependent manner. The number of apoptotic cells and the content of cytochrome c were significantly increased by NCTD treatment but that of mitochondrial membrane was decreased. Moreover, the expression of bcl-2 and caspase-3 was prompted by NCTD, but the expression of bax, MMP-2, and MMP-9 in 25% FBS-treated HMCs was inhibited. In addition, NCTD markedly unregulated the expression of apoptosis-related gene/protein, including p-Erk1/2, phosphorylated-Jun N-terminal kinase (JNK), p-p38, and p53.

CONCLUSION

NCTD enhances 25% FBS-treated HMC apoptosis in vitro, and this effect may be attributed to the modulation of the ERK, JNK, and p38 mitogen-activated protein kinase signaling pathways.

Augmented O-GlcNAcylation attenuates intermittent hypoxia-induced cardiac remodeling through the suppression of NFAT and NF-κB activities in mice

Type 2 diabetes mellitus (T₂DM) has been reported to be associated with cardiac remodeling. Although O-GlcNAcylation is known to be elevated in diabetic and ischemic hearts, the effects of O-GlcNAcylation on cardiac remodeling induced by intermittent hypoxia (IH), such as sleep apnea syndrome (SAS), remain unknown. To evaluate the effects, we induced IH in wild-type (WT) and transgenic O-GlcNAc transferase (Ogt-Tg) mice. Two weeks of IH increased O-GlcNAcylation in the heart tissues of both strains of mice, whereas O-GlcNAcylation in Ogt-Tg mice was significantly higher than that in WT mice under both normoxic and IH conditions. WT mice exhibited cardiac remodeling after IH, whereas cardiac remodeling was significantly attenuated in Ogt-Tg mice. Oxidative stress and apoptosis increased after IH in both strains of mice, whereas the rate of increase in these processes in Ogt-Tg mice was significantly lower than that in WT mice. To examine the mechanism of cardiac remodeling attenuation in Ogt-Tg mice after IH, the effects of O-GlcNAcylation on the activities of the master regulators nuclear factor of activated T cells (NFAT) and NF-κB were determined. The O-GlcNAcylation of GSK-3β, a negative regulator of NFAT, was significantly increased in Ogt-Tg mice, whereas the phosphorylation of GSK-3β was reciprocally reduced. The same result was observed for NF-κB p65. An in vitro reporter assay showed that the augmentation of O-GlcNAcylation by an O-GlcNAcase inhibitor suppressed NFAT and NF-κB promoter activity. These data suggest that augmented O-GlcNAcylation mitigates IH-induced cardiac remodeling by suppressing NFAT and NF-κB activities through the O-GlcNAcylation of GSK-3β and NF-κB p65.

Exosomes Derived from Bovine Mammary Epithelial Cells Treated with Transforming Growth Factor-β1 Inhibit the Proliferation of Bovine Macrophages

Transforming growth factor (TGF)-β1 is a multifunctional cytokine that plays an important role in regulating immune cell proliferation. We speculate that high expression of TGF-β1 may affect the immunity of dairy cows. In this study, untreated exosomes (un-exo) derived from an untreated bovine mammary epithelial cell line (MAC-T) and TGF-β1-treated exosomes (t-exo) derived from TGF-β1-treated MAC-T cells were isolated by ultracentrifugation and identified by electron microscopy and Western blotting. Then, un-exo and t-exo were used to treat a bovine macrophage cell line (BOSMAC), and the proliferative ability of BOSMAC cells was detected by an 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay and flow cytometry. The expression and phosphorylation levels of p38 were analyzed by q-PCR and Western blotting. The results showed that both exosome types exhibited the basic characteristics of exosomes. In BOSMAC cells treated with t-exo, significant inhibition of cell proliferation was observed, and the cell cycle progression was inhibited, while no difference was found between the un-exo and control groups. Only treatment with t-exo increased the expression and phosphorylation of p38, and the addition of the p38 inhibitor SB203580 abrogated the inhibition of BOSMAC cell proliferation by t-exo. Our results demonstrated that t-exo inhibited the proliferation of bovine macrophages by stimulating p38 MAPK and might interfere with immunity in dairy cattle. This finding may provide a new strategy for improving immunity and preventing breast-related diseases in dairy cows.

Emerging role of glycosylation in the polarization of tumor-associated macrophages

Tumors are formed by several cell types interacting in a complex environment of soluble and matrix molecules. The crosstalk between the cells and extracellular components control tumor fate. Macrophages are highly plastic and diverse immune cells that are known to be key regulators of this complex network, which is mostly because they can adjust their metabolism and reprogram their phenotype and effector function. Here, we review the studies that disclose the central role of metabolism and tumor microenvironment in shaping the phenotype and function of macrophages, highlighting the importance of the hexosamine biosynthetic pathway. We further discuss growing evidence of nutrient-sensitive protein modifications such as O-GlcNAcylation and extracellular glycosylation in the function and polarization of tumor-associated macrophages.

Quercetin induces cell death in cervical cancer by reducing O-GlcNAcylation of adenosine monophosphate-activated protein kinase

Hyper-O-GlcNAcylation is a general feature of cancer which contributes to various cancer phenotypes, including cell proliferation and cell growth. Quercetin, a naturally occurring dietary flavonoid, has been reported to reduce the proliferation and growth of cancer. Several reports of the anticancer effect of quercetin have been published, but there is no study regarding its effect on O-GlcNAcylation. The aim of this study was to investigate the anticancer effect of quercetin on HeLa cells and compare this with its effect on HaCaT cells. Cell viability and cell death were determined by MTT and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling assays. O-GlcNAcylation of AMP-activated protein kinase (AMPK) was examined by succinylated wheat germ agglutinin pulldown and immunoprecipitation. Immunofluorescence staining was used to detect the immunoreactivitiy of O-linked N-acetylglucosamine transferase (OGT) and sterol regulatory element binding protein 1 (SREBP-1). Quercetin decreased cell proliferation and induced cell death, but its effect on HaCaT cells was lower than that on HeLa cells. O-GlcNAcylation level was higher in HeLa cells than in HaCaT cells. Quercetin decreased the expression of global O-GlcNAcylation and increased AMPK activation by reducing the O-GlcNAcylation of AMPK. AMPK activation due to reduced O-GlcNAcylation of AMPK was confirmed by treatment with 6-diazo-5-oxo-L-norleucine. Our results also demonstrated that quercetin regulated SREBP-1 and its transcriptional targets. Furthermore, immunofluorescence staining showed that quercetin treatment decreased the immunoreactivities of OGT and SREBP-1 in HeLa cells. Our findings demonstrate that quercetin exhibited its anticancer effect by decreasing the O-GlcNAcylation of AMPK. Further studies are needed to explore how quercetin regulates O-GlcNAcylation in cancer.

α-cyano-4-hydroxycinnamate impairs pancreatic cancer cells by stimulating the p38 signaling pathway

Multiple studies are currently targeting dysregulated cancer cell metabolism with distinct combinations of inhibitors. In this study, we evaluated in pancreatic cancer cells metformin, which blocks oxidative phosphorylation, in combination with α-cyano-4-hydroxycinnamate, which has been reported to inhibit the export of lactate from the cytosol. The combination of metformin with α-cyano-4-hydroxycinnamate had a major inhibitory effect on the migration of 6606PDA cells. Monotherapy with α-cyano-4-hydroxycinnamate and especially the combination with metformin also caused significant inhibition of cell proliferation and induced cell death. α-cyano-4-hydroxycinnamate in combination with metformin reduced the export of lactate significantly, whereas α-cyano-4-hydroxycinnamate monotherapy only modestly influenced lactate export. None of these two drugs inhibited the expression of distinct glycolytic enzymes. Interestingly, α-cyano-4-hydroxycinnamate rather inhibited the ERK and very strongly stimulated the p38 signaling pathway in 6606PDA as well as in 7265PDA cells. In addition, the inhibition of the p38 signaling pathway by PH-797804 partially reversed the effect of α-cyano-4-hydroxycinnamate on cell apoptosis in both cell lines. We conclude that α-cyano-4-hydroxycinnamate monotherapy and especially the combinatorial therapy with metformin has strong anti-cancerous effects. α-cyano-4-hydroxycinnamate causes cancer cell apoptosis by a novel mechanism for this drug, namely the stimulation of the p38 signaling pathway.

Augmented O-GlcNAcylation alleviates inflammation-mediated colon carcinogenesis via suppression of acute inflammation

Colon cancer prevalence is high worldwide. O-GlcNAcylation has been associated with tumor growth in various tissues, including the colon; however, its link to carcinogenesis is not fully understood. We investigated the association of O-GlcNAcylation with colon carcinogenesis using a 1,2-dimethylhydrazine/dextran sodium sulfate-induced colon carcinogenesis model in wild type and O-GlcNAc transferase-transgenic (Ogt-Tg) mice. The incidence of colon cancer was significantly lower in Ogt-Tg than in wild type mice. The colonic length was not shortened in Ogt-Tg mice, and NF-κB p65 phosphorylation was strongly suppressed, indicating that reduction of inflammation might be related to the alleviation of colon carcinogenesis. Dextran sodium sulfate-induced acute colitis mice were used to evaluate the effect of O-GlcNAcylation on inflammation at the maximal inflammation period. In Ogt-Tg mice, NF-κB p65 phosphorylation and interleukin-1β mRNA expression were suppressed. Histochemical staining demonstrated shedding of colon epithelial cells in wild type mice a few days after dextran sodium sulfate treatment, whereas they remained essentially intact in Ogt-Tg mice. There were no significant differences on histochemical staining in the remaining epithelia between groups. These data suggest that O-GlcNAcylation could prevent colon carcinogenesis through reducing acute maximum inflammation, suggesting modulation of O-GlcNAcylation as a novel therapeutic option.

Smurf1 regulates macrophage proliferation, apoptosis and migration via JNK and p38 MAPK signaling pathways

Smad ubiquitylation regulatory factor 1 (Smurf1) has been identified to play a critical role in bone homeostasis, development, cell cycle regulation and tumorigenesis. However, the role of Smurf1 in macrophage proliferation, apoptosis and migration is still unclear. Here, we show that Smurf1 expression was elevated in LPS-induced RAW264.7 macrophage and mouse embryonic fibroblasts (MEFs). And we found that knockdown of Smurf1 suppresses macrophage proliferation but promotes apoptosis and migration. Furthermore, JNK and p38 MAPK signaling were upregulated in Smurf1-depleted cells. And inhibition of JNK and p38 MAPK signaling in Smurf1 knockdown cells rescue the phenotypes of macrophage proliferation, apoptosis and migration. Therefore, our study suggests that Smurf1 is a new positive regulator for macrophage proliferation and apoptosis, but a negative regulator for macrophage migration.

Elevated O-GlcNAcylation stabilizes FOXM1 by its reduced degradation through GSK-3β inactivation in a human gastric carcinoma cell line, MKN45 cells

O-GlcNAcylation is a dynamic post-translational modification of cytonuclear proteins for intracellular signaling. Elevated O-GlcNAcylation is a general feature of cancer and contributes to cancer progression, and recent studies indicate the contribution to increasing incidence of various types of cancer in diabetic patients. However, the role of O-GlcNAcylation in tumor progression is not fully elucidated. Forkhead box M1 (FOXM1), a master mitotic transcription factor, has been implicated in all major hallmarks of cancer, and is wildly expressed in solid tumors. Given that FOXM1 expression was reported to be elevated in gastric cancer, we examined the effect of high glucose or an inhibitor of O-GlcNAc hydrolase, Thiamet G (TMG), on FOXM1 protein expression in a human gastric cancer cell line, MKN45 cells, and confirmed that FOXM1 protein level and the cell proliferation were upregulated. To investigate the molecular mechanisms by which FOXM1 protein expression is regulated by O-GlcNAcylation, the effect of high glucose and TMG on FOXM1 ubiquitination was examined in MKN45 cells. As a result, the ubiquitination and degradation of FOXM1 protein were both suppressed by high glucose and TMG treatment. However, the O-GlcNAcylation was not detected on FOXM1 but not on GSK-3β. High glucose and TMG treatment increased phospho-serine 9 GSK-3β, an inactive form, and the degradation of FOXM1 protein was suppressed by treatment of GSK-3β inhibitors in MKN45 cells. Taken together, we suggest that high glucose and elevated O-GlcNAcylation stabilize FOXM1 protein by its reduced degradation via GSK-3β inactivation in MKN45 cells, suggesting that the higher risk of gastric cancer in diabetic patients could be partially due to O-GlcNAcylation-mediated FOXM1 stabilization.

Augmented O-GlcNAcylation of AMP-activated kinase promotes the proliferation of LoVo cells, a colon cancer cell line

Increasing incidence of various cancers has been reported in diabetic patients. O‐linked N‐acetylglucosamine (O‐GlcNAc) modification of proteins at serine/threonine residues (O‐GlcNAcylation) is an essential post‐translational modification that is upregulated in diabetic patients and has been implicated in tumor growth. However, the mechanisms by which O‐GlcNAcylation promotes tumor growth remain unclear. Given that AMP‐activated kinase (AMPK) has been thought to play important roles in suppressing tumor growth, we evaluated the involvement of AMPK O‐GlcNAcylation on the growth of LoVo cells, a human colon cancer cell line. Results revealed that treatment with Thiamet G (TMG), an inhibitor of O‐GlcNAc hydrolase, increased both anchorage‐dependent and ‐independent growth of the cells. O‐GlcNAc transferase overexpression also increased the growth. These treatments increased AMPK O‐GlcNAcylation in a dose‐dependent manner, which led to reduced AMPK phosphorylation and mTOR activation. Chemical inhibition or activation of AMPK led to increased or decreased growth, respectively, which was consistent with the data with genetic inhibition of AMPK. In addition, TMG‐mediated acceleration of tumor growth was abolished by both chemical and genetic inhibition of AMPK. To examine the effects of AMPK O‐GlcNAcylation in vivo, the LoVo cells were s.c. transplanted onto the backs of BALB/c‐nu/nu mice. Injection of TMG promoted the growth and enhanced O‐GlcNAcylation of the tumors of the mice. Consistent with in vitro data, AMPK O‐GlcNAcylation was increased, which reduced AMPK phosphorylation and resulted in activation of mTOR. Collectively, the higher colon cancer risk of diabetic patients could be due to O‐GlcNAcylation‐mediated AMPK inactivation and subsequent activation of mTOR.